I study auctions in which firms bid for licenses that reduce their marginal costs in a post-auction downstream market. When there are three or more firms, I show that the Vickrey--Clarke--Groves (VCG) auction maximizes consumer surplus in dominant strategies if and only if it maximizes producer surplus in dominant strategies. With two firms, the effect on consumer surplus is ambiguous. When the VCG auction does not maximize consumer surplus, I show that consumer surplus can be maximized by adding the right caps, i.e., restricting the number of licenses a bidder can win. This might lower producer surplus.
{"title":"When Can Auctions Maximize Post-Auction Welfare?","authors":"Bernhard Kasberger","doi":"10.2139/ssrn.3519866","DOIUrl":"https://doi.org/10.2139/ssrn.3519866","url":null,"abstract":"I study auctions in which firms bid for licenses that reduce their marginal costs in a post-auction downstream market. When there are three or more firms, I show that the Vickrey--Clarke--Groves (VCG) auction maximizes consumer surplus in dominant strategies if and only if it maximizes producer surplus in dominant strategies. With two firms, the effect on consumer surplus is ambiguous. When the VCG auction does not maximize consumer surplus, I show that consumer surplus can be maximized by adding the right caps, i.e., restricting the number of licenses a bidder can win. This might lower producer surplus.","PeriodicalId":18516,"journal":{"name":"Microeconomics: Production","volume":"252 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73854301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Cobb-Douglas production function (the C-D function) is believed to have successfully validated and consolidated the marginal productivity theory of income distribution (MPTID) and the aggregate production function (APF). However, this paper discovers that this success is an illusion. It demonstrates neither the partial derivatives of the C-D function are as believed to be the marginal productivities of production factors nor its homogeneity is as believed to be a technical result of the constant returns to scale (CRS). Without these believed theoretical contents, the C-D function is further shown to be just a mathematical transformation of the national income identity. It is in fact not a production function as it does not truly summarize any productive behavior or technological relationships. The illusion should have been one of the reasons why the mainstream macro models, of which the C-D function alike is one of the cornerstones, have been struggling with the identification problems and failed to foresee the GFC. Methodologically, the illusion is a result of grafting dynamic data upon the static concept of marginal productivity and confusing the concept of CRS with the fact that the sum of all factor’s income shares must equal 1.
{"title":"The Success of the Cobb-Douglas Production Function Is An Illusion","authors":"Yuming Sheng","doi":"10.2139/ssrn.3666648","DOIUrl":"https://doi.org/10.2139/ssrn.3666648","url":null,"abstract":"The Cobb-Douglas production function (the C-D function) is believed to have successfully validated and consolidated the marginal productivity theory of income distribution (MPTID) and the aggregate production function (APF). However, this paper discovers that this success is an illusion. It demonstrates neither the partial derivatives of the C-D function are as believed to be the marginal productivities of production factors nor its homogeneity is as believed to be a technical result of the constant returns to scale (CRS). Without these believed theoretical contents, the C-D function is further shown to be just a mathematical transformation of the national income identity. It is in fact not a production function as it does not truly summarize any productive behavior or technological relationships. The illusion should have been one of the reasons why the mainstream macro models, of which the C-D function alike is one of the cornerstones, have been struggling with the identification problems and failed to foresee the GFC. Methodologically, the illusion is a result of grafting dynamic data upon the static concept of marginal productivity and confusing the concept of CRS with the fact that the sum of all factor’s income shares must equal 1.","PeriodicalId":18516,"journal":{"name":"Microeconomics: Production","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85415777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A data broker sells market segmentations created by consumer data to a producer with private production cost who sells a product to a unit mass of consumers with heterogeneous values. In this setting, I completely characterize the revenue-maximizing mechanisms for the data broker. In particular, every optimal mechanism induces quasi-perfect price discrimination. That is, the data broker sells the producer a market segmentation described by a cost-dependent cutoff, such that all the consumers with values above the cutoff end up buying and paying their values while the rest of consumers do not buy. The characterization of optimal mechanisms leads to additional economically relevant implications. I show that the induced market outcomes remain unchanged even if the data broker becomes more active in the product market by gaining the ability to contract on prices; or by becoming an exclusive retailer, who purchases both the product and the exclusive right to sell the product from the producer, and then sells to the consumers directly. Moreover, vertical integration between the data broker and the producer increases total surplus while leaving the consumer surplus unchanged, since consumer surplus is zero under any optimal mechanism for the data broker.
{"title":"Selling Consumer Data for Profit: Optimal Market Segmentation Design and its Consequences","authors":"K. Yang","doi":"10.2139/ssrn.3675883","DOIUrl":"https://doi.org/10.2139/ssrn.3675883","url":null,"abstract":"A data broker sells market segmentations created by consumer data to a producer with private production cost who sells a product to a unit mass of consumers with heterogeneous values. In this setting, I completely characterize the revenue-maximizing mechanisms for the data broker. In particular, every optimal mechanism induces quasi-perfect price discrimination. That is, the data broker sells the producer a market segmentation described by a cost-dependent cutoff, such that all the consumers with values above the cutoff end up buying and paying their values while the rest of consumers do not buy. The characterization of optimal mechanisms leads to additional economically relevant implications. I show that the induced market outcomes remain unchanged even if the data broker becomes more active in the product market by gaining the ability to contract on prices; or by becoming an exclusive retailer, who purchases both the product and the exclusive right to sell the product from the producer, and then sells to the consumers directly. Moreover, vertical integration between the data broker and the producer increases total surplus while leaving the consumer surplus unchanged, since consumer surplus is zero under any optimal mechanism for the data broker.","PeriodicalId":18516,"journal":{"name":"Microeconomics: Production","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76832370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper proposes a two-stage sealed-bid model for the execution of blind portfolios. An asset manager auctions a package of securities to a set of brokers who are unaware of the specific details about individual securities. We prove that our mechanism reduces the costs of execution for the asset manager and eliminates the winner's curse for participating brokers.
{"title":"Blind Portfolios’ Auctions in Two-Rounds","authors":"Lamprini Zarpala, Dimitris Voliotis","doi":"10.2139/ssrn.3662384","DOIUrl":"https://doi.org/10.2139/ssrn.3662384","url":null,"abstract":"This paper proposes a two-stage sealed-bid model for the execution of blind portfolios. An asset manager auctions a package of securities to a set of brokers who are unaware of the specific details about individual securities. We prove that our mechanism reduces the costs of execution for the asset manager and eliminates the winner's curse for participating brokers.","PeriodicalId":18516,"journal":{"name":"Microeconomics: Production","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90972364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study contributes new evidence on why the Middle East and North Africa (MENA) region has failed to create decent jobs for decades. The growth accounting exercise reveals that the region suffered from an acute total factor productivity (TFP) deficit in the 1990s; it improved remarkably in the 2000s, before deteriorating significantly in the period between 2010 and 2017. Throughout the three subperiods, the region’s growth relied heavily on capital accumulation. The severe deficit in TFP and the heavy reliance on physical capital for decades impaired the region’s ability to sustain economic growth and to create decent jobs in the long run. The study recommends more government interventions in knowledge accumulation as a critical precondition for employment generation in developing countries.
{"title":"Are Developing Countries Accumulating Sufficient Total Factor Productivity to Sustain Their Economic Growth and Job Creation? Empirical Evidence from the Middle East and North Africa Region","authors":"M. A. Abou Hamia","doi":"10.1111/rode.12693","DOIUrl":"https://doi.org/10.1111/rode.12693","url":null,"abstract":"This study contributes new evidence on why the Middle East and North Africa (MENA) region has failed to create decent jobs for decades. The growth accounting exercise reveals that the region suffered from an acute total factor productivity (TFP) deficit in the 1990s; it improved remarkably in the 2000s, before deteriorating significantly in the period between 2010 and 2017. Throughout the three subperiods, the region’s growth relied heavily on capital accumulation. The severe deficit in TFP and the heavy reliance on physical capital for decades impaired the region’s ability to sustain economic growth and to create decent jobs in the long run. The study recommends more government interventions in knowledge accumulation as a critical precondition for employment generation in developing countries.","PeriodicalId":18516,"journal":{"name":"Microeconomics: Production","volume":"189 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82450292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We empirically test the hypothesis that the discounts offered by firms to consumers who purchase tickets in advance increase with the intensity of competition. We develop a new measure of competition for which we use the proximity (in departure time) of a given flight to its competitors to infer the intensity of competition and estimate the impact of competition on advance purchase discounts (APDs) and the dynamic pricing of airlines by exploiting plausibly exogenous changes in the flight schedules of airlines that occur during the booking period. We find strong support for the theoretical prediction that APDs are larger when the intensity of competition is higher using a sample of airline fare quotes. Our results also suggest that airline price dispersion increases with the intensity of competition.
{"title":"On the Benefits of Being Alone: Scheduling Changes, Intensity of Competition and Dynamic Airline Pricing","authors":"Yannis Kerkemezos, Bas Karreman","doi":"10.2139/ssrn.3655067","DOIUrl":"https://doi.org/10.2139/ssrn.3655067","url":null,"abstract":"We empirically test the hypothesis that the discounts offered by firms to consumers who purchase tickets in advance increase with the intensity of competition. We develop a new measure of competition for which we use the proximity (in departure time) of a given flight to its competitors to infer the intensity of competition and estimate the impact of competition on advance purchase discounts (APDs) and the dynamic pricing of airlines by exploiting plausibly exogenous changes in the flight schedules of airlines that occur during the booking period. We find strong support for the theoretical prediction that APDs are larger when the intensity of competition is higher using a sample of airline fare quotes. Our results also suggest that airline price dispersion increases with the intensity of competition.<br>","PeriodicalId":18516,"journal":{"name":"Microeconomics: Production","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88901391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper explains that that the decision of a marketplace to operate its own reseller in competition with third-party sellers within the platform is likely to spur competition to the ultimate benefit of consumers. A marketplace will profit by supplying directly as a reseller when that duality is needed to (a) achieve selection parity with other distribution channels and/or (b) prod third-party sellers to compete more aggressively. The success of a hybrid marketplace (i.e. an online business that is both a marketplace and a reseller operating in that marketplace) may require it to support its retail operations in order to increase the appeal of its store vis-à-vis other stores. The effect of such strategy on the incentives to innovate of other sellers in the marketplace is in principle ambiguous but the available evidence suggests it may be positive.
{"title":"The Simple Economics of Hybrid Marketplaces","authors":"Neil Dryden, Sergey Khodjamirian, Jorge Padilla","doi":"10.2139/ssrn.3650903","DOIUrl":"https://doi.org/10.2139/ssrn.3650903","url":null,"abstract":"This paper explains that that the decision of a marketplace to operate its own reseller in competition with third-party sellers within the platform is likely to spur competition to the ultimate benefit of consumers. A marketplace will profit by supplying directly as a reseller when that duality is needed to (a) achieve selection parity with other distribution channels and/or (b) prod third-party sellers to compete more aggressively. The success of a hybrid marketplace (i.e. an online business that is both a marketplace and a reseller operating in that marketplace) may require it to support its retail operations in order to increase the appeal of its store vis-à-vis other stores. The effect of such strategy on the incentives to innovate of other sellers in the marketplace is in principle ambiguous but the available evidence suggests it may be positive.","PeriodicalId":18516,"journal":{"name":"Microeconomics: Production","volume":"67 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76818091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We study a robust auction design problem with a minimax regret objective, where a seller seeks a mechanism for selling multiple items to multiple bidders with additive values. The seller knows that the bidders' values range over a box uncertainty set but has no information on their probability distribution. We propose a mechanism that sells each item separately via a second price auction with a random reserve price and characterize an upper bound on its optimality gap. We show that this upper bound vanishes and that the proposed auction becomes optimal if the bidders are symmetric. We then interpret the auction design problem as a zero-sum game between the seller, who chooses a mechanism, and a fictitious adversary or 'nature,' who chooses the bidders' values from within the uncertainty set with the aim to maximize the seller's regret. We characterize the Nash equilibrium of this game analytically when the bidders are symmetric. The Nash strategy of the seller coincides with the optimal separable second price auction, whereas the Nash strategy of nature is mixed and constitutes a probability distribution on the uncertainty set under which each bidder's values for the items are comonotonic. We also study a restricted auction design problem over deterministic mechanisms. In this setting, we characterize the suboptimality of a separable second price auction with deterministic reserve prices and show that this auction becomes optimal if the bidders are symmetric.
{"title":"Regret Minimization and Separation in Multi-Bidder Multi-Item Auctions","authors":"Çagil Koçyigit, D. Kuhn, Napat Rujeerapaiboon","doi":"10.2139/ssrn.3636395","DOIUrl":"https://doi.org/10.2139/ssrn.3636395","url":null,"abstract":"We study a robust auction design problem with a minimax regret objective, where a seller seeks a mechanism for selling multiple items to multiple bidders with additive values. The seller knows that the bidders' values range over a box uncertainty set but has no information on their probability distribution. We propose a mechanism that sells each item separately via a second price auction with a random reserve price and characterize an upper bound on its optimality gap. We show that this upper bound vanishes and that the proposed auction becomes optimal if the bidders are symmetric. We then interpret the auction design problem as a zero-sum game between the seller, who chooses a mechanism, and a fictitious adversary or 'nature,' who chooses the bidders' values from within the uncertainty set with the aim to maximize the seller's regret. We characterize the Nash equilibrium of this game analytically when the bidders are symmetric. The Nash strategy of the seller coincides with the optimal separable second price auction, whereas the Nash strategy of nature is mixed and constitutes a probability distribution on the uncertainty set under which each bidder's values for the items are comonotonic. We also study a restricted auction design problem over deterministic mechanisms. In this setting, we characterize the suboptimality of a separable second price auction with deterministic reserve prices and show that this auction becomes optimal if the bidders are symmetric.","PeriodicalId":18516,"journal":{"name":"Microeconomics: Production","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80493008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study examines the estimation of the exchangeable joint distribution when the highest (lowest) and another order statistics are observable. The estimator would be appropriate for the estimation of the valuation distribution of auctions and "order-biased" sampling, such as school student achievement investigations, when the sampling probability is not completely captured by the observed covariates. We present our method in conjunction with an application for a first-price sealed-bid auction with affiliation. The results potentially extend the existing non-parametric identification result for first-price sealed-bid auctions with symmetric affiliation.
{"title":"Estimation of Exchangeable Distribution with Order Statistics: Application to First-Price Auctions","authors":"Hayato Nakanishi","doi":"10.2139/ssrn.3440360","DOIUrl":"https://doi.org/10.2139/ssrn.3440360","url":null,"abstract":"This study examines the estimation of the exchangeable joint distribution when the highest (lowest) and another order statistics are observable. The estimator would be appropriate for the estimation of the valuation distribution of auctions and \"order-biased\" sampling, such as school student achievement investigations, when the sampling probability is not completely captured by the observed covariates. We present our method in conjunction with an application for a first-price sealed-bid auction with affiliation. The results potentially extend the existing non-parametric identification result for first-price sealed-bid auctions with symmetric affiliation.","PeriodicalId":18516,"journal":{"name":"Microeconomics: Production","volume":"542 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74726876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-11DOI: 10.2499/p15738coll2.133757
Hiroyuki Takeshima, Anjani Kumar
Heterogeneity in factor endowments and the degree of specializations induced by comparative advantages are among the crucial factors that affect the overall productivity of the economy. Few studies, however, investigate what strengthens such endowment-related specialization patterns in the agricultural sector in low-income countries, although such evolutions have profound effects on the role of factor endowments in households’ behaviors. This is in contrast to well-established international trade theory, such as the Heckscher–Ohlin theorem which describes how heterogeneity in endowment across countries gives rise to comparative advantages for specialization and trade. We partly fill this critical knowledge gap by providing a set of evidence from Nepal, which is a country that has historically been dominated by smallholder farmers and yet has recently been experiencing rapid structural transformation within the agricultural sector. Specifically, we show the following: the agricultural sector in Nepal has experienced a significant increase in returns-to-scale (RTS) in production in recent years during the process of growing adoptions of agricultural mechanization through the custom-hiring market. Such increase in RTS has primarily strengthened the linkages between factor endowment heterogeneity (across farm households) and their specialization behaviors in labor, land, and the agricultural capital market. Both cross-section and panel-data of households in Nepal extracted from Nepal Living Standards Surveys are used to generate this evidence. We find that rising RTS associated primarily with tractor use growth has been inducing greater exploitations of comparative advantages; agricultural households have been increasingly specializing in exchanges of production factors, services, and outputs, in ways consistent with predictions based on their relative factor endowments. Specifically, the rise in RTS has induced households with more labor, land, and capital endowments to rent out their labor, land, and credit, respectively, within the agricultural sector, while increasingly renting-in the other factors with which they are less endowed. The results suggest that understanding factor endowments heterogeneity among agricultural households is becoming increasingly important for effective agricultural policy designs in countries like Nepal, where employment shares in the agricultural sector remain high despite the growth in mechanization.
{"title":"Changing Returns-to-Scale and Deepening of Factor-Endowments-Induced Specialization: Exploring Broader Linkage Between Agricultural Mechanization and Agricultural Transformation in Nepal","authors":"Hiroyuki Takeshima, Anjani Kumar","doi":"10.2499/p15738coll2.133757","DOIUrl":"https://doi.org/10.2499/p15738coll2.133757","url":null,"abstract":"Heterogeneity in factor endowments and the degree of specializations induced by comparative advantages are among the crucial factors that affect the overall productivity of the economy. Few studies, however, investigate what strengthens such endowment-related specialization patterns in the agricultural sector in low-income countries, although such evolutions have profound effects on the role of factor endowments in households’ behaviors. This is in contrast to well-established international trade theory, such as the Heckscher–Ohlin theorem which describes how heterogeneity in endowment across countries gives rise to comparative advantages for specialization and trade. We partly fill this critical knowledge gap by providing a set of evidence from Nepal, which is a country that has historically been dominated by smallholder farmers and yet has recently been experiencing rapid structural transformation within the agricultural sector. Specifically, we show the following: the agricultural sector in Nepal has experienced a significant increase in returns-to-scale (RTS) in production in recent years during the process of growing adoptions of agricultural mechanization through the custom-hiring market. Such increase in RTS has primarily strengthened the linkages between factor endowment heterogeneity (across farm households) and their specialization behaviors in labor, land, and the agricultural capital market. Both cross-section and panel-data of households in Nepal extracted from Nepal Living Standards Surveys are used to generate this evidence. We find that rising RTS associated primarily with tractor use growth has been inducing greater exploitations of comparative advantages; agricultural households have been increasingly specializing in exchanges of production factors, services, and outputs, in ways consistent with predictions based on their relative factor endowments. Specifically, the rise in RTS has induced households with more labor, land, and capital endowments to rent out their labor, land, and credit, respectively, within the agricultural sector, while increasingly renting-in the other factors with which they are less endowed. The results suggest that understanding factor endowments heterogeneity among agricultural households is becoming increasingly important for effective agricultural policy designs in countries like Nepal, where employment shares in the agricultural sector remain high despite the growth in mechanization.","PeriodicalId":18516,"journal":{"name":"Microeconomics: Production","volume":"51 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88918508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：