Using novel monthly data for 226 euro-area banks from 2007 to 2015, we investigate the determinants of changes in banks’ sovereign exposures and their effects during and after the crisis. First, public, bailed out and poorly capitalized banks responded to sovereign stress by purchasing domestic public debt more than other banks, with public banks’ purchases growing especially in coincidence with the largest ECB liquidity injections. Second, bank exposures significantly amplified the transmission of risk from the sovereign and its impact on lending. This amplification of the impact on lending does not appear to arise from spurious correlation or reverse causality.
{"title":"Bank Exposures and Sovereign Stress Transmission","authors":"Carlo Altavilla, M. Pagano, S. Simonelli","doi":"10.2139/ssrn.2640131","DOIUrl":"https://doi.org/10.2139/ssrn.2640131","url":null,"abstract":"Using novel monthly data for 226 euro-area banks from 2007 to 2015, we investigate the determinants of changes in banks’ sovereign exposures and their effects during and after the crisis. First, public, bailed out and poorly capitalized banks responded to sovereign stress by purchasing domestic public debt more than other banks, with public banks’ purchases growing especially in coincidence with the largest ECB liquidity injections. Second, bank exposures significantly amplified the transmission of risk from the sovereign and its impact on lending. This amplification of the impact on lending does not appear to arise from spurious correlation or reverse causality.","PeriodicalId":9906,"journal":{"name":"CEPR: Financial Economics (Topic)","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87199260","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 : 2016-03-01DOI: 10.1017/9781316636404.013
T. Beck, E. Carletti, Itay Goldstein
This chapter discusses recent regulatory reforms and relates them to different market failures in banking, based on the recent theoretical and empirical literature with focus on insights from the recent crisis. We also provide a broader discussion of challenges in financial sector regulation, related to the regulatory perimeter and financial innovation as tools financial market participants use to evade tighter regulatory frameworks. We argue for a dynamic view of regulation that takes into account the changing nature of risk-taking activities and regulatory arbitrage efforts. We also stress the need for a balanced approach between complex and simple tools, a strong focus on systemic in addition to idiosyncratic regulation, and a stronger emphasis on the resolution phase of financial regulation.
{"title":"Financial Regulation in Europe: Foundations and Challenges","authors":"T. Beck, E. Carletti, Itay Goldstein","doi":"10.1017/9781316636404.013","DOIUrl":"https://doi.org/10.1017/9781316636404.013","url":null,"abstract":"This chapter discusses recent regulatory reforms and relates them to different market failures in banking, based on the recent theoretical and empirical literature with focus on insights from the recent crisis. We also provide a broader discussion of challenges in financial sector regulation, related to the regulatory perimeter and financial innovation as tools financial market participants use to evade tighter regulatory frameworks. We argue for a dynamic view of regulation that takes into account the changing nature of risk-taking activities and regulatory arbitrage efforts. We also stress the need for a balanced approach between complex and simple tools, a strong focus on systemic in addition to idiosyncratic regulation, and a stronger emphasis on the resolution phase of financial regulation.","PeriodicalId":9906,"journal":{"name":"CEPR: Financial Economics (Topic)","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74950206","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 the determinants of private benefits of control in negotiated block transactions. We estimate the block pricing model in Burkart, Gromb, and Panunzi (2000) explicitly dealing with the existence of both block premia and block discounts in the data. We find evidence that the occurrence of block premia and block discounts depends on the controlling block holder's ability to fight a potential tender offer for the target's stock. Private benefits represent 3% of the target firm's stock market value. Private benefits increase with the target's cash holdings and decrease with its short term debt providing evidence in favor of Jensen's free cash flow hypothesis. A counterfactual policy evaluation of the Mandatory Bid Rule suggests that it fails to add value to shareholders because it fails to prevent welfare decreasing transactions and, by forcing inefficient tender offers, it deters welfare increasing transactions.
{"title":"Determinants of the Block Premium and of Private Benefits of Control","authors":"R. Albuquerque, Enrique J. Schroth","doi":"10.2139/ssrn.1099901","DOIUrl":"https://doi.org/10.2139/ssrn.1099901","url":null,"abstract":"We study the determinants of private benefits of control in negotiated block transactions. We estimate the block pricing model in Burkart, Gromb, and Panunzi (2000) explicitly dealing with the existence of both block premia and block discounts in the data. We find evidence that the occurrence of block premia and block discounts depends on the controlling block holder's ability to fight a potential tender offer for the target's stock. Private benefits represent 3% of the target firm's stock market value. Private benefits increase with the target's cash holdings and decrease with its short term debt providing evidence in favor of Jensen's free cash flow hypothesis. A counterfactual policy evaluation of the Mandatory Bid Rule suggests that it fails to add value to shareholders because it fails to prevent welfare decreasing transactions and, by forcing inefficient tender offers, it deters welfare increasing transactions.","PeriodicalId":9906,"journal":{"name":"CEPR: Financial Economics (Topic)","volume":"46 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2008-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75328733","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 the link between culturally inherited household structure and wealth distribution in international comparisons using household data for the US and Spain (the SCF and the EFF). We estimate counterfactual US distributions relying on the panish household structure. Our results show that differences in household structure account for most of the differences in the lower part of the distribution between the two countries, but mask even larger differences in the upper part of the distribution. Imposing the Spanish household structure to the US wealth distribution has little effect on summary measures of inequality. However, this is the net result of reduced differences at the bottom and increased differences at the top. So there is distinct additional information in considering the whole distribution. We also report some evidence of an association between these wealth distribution differences and wealth composition. Finally, we present results for the within-group differences between the two countries using quantile regressions and find a reversing pattern by age.
{"title":"Wealth Inequality and Household Structure: US vs. Spain","authors":"O. Bover","doi":"10.2139/ssrn.1093617","DOIUrl":"https://doi.org/10.2139/ssrn.1093617","url":null,"abstract":"We study the link between culturally inherited household structure and wealth distribution in international comparisons using household data for the US and Spain (the SCF and the EFF).\u0000We estimate counterfactual US distributions relying on the panish household structure. Our results show that differences in household structure account for most of the differences in\u0000the lower part of the distribution between the two countries, but mask even larger\u0000differences in the upper part of the distribution. Imposing the Spanish household structure to\u0000the US wealth distribution has little effect on summary measures of inequality. However, this\u0000is the net result of reduced differences at the bottom and increased differences at the top.\u0000So there is distinct additional information in considering the whole distribution. We also\u0000report some evidence of an association between these wealth distribution differences and\u0000wealth composition. Finally, we present results for the within-group differences between the\u0000two countries using quantile regressions and find a reversing pattern by age.","PeriodicalId":9906,"journal":{"name":"CEPR: Financial Economics (Topic)","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2008-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83690801","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}
Recent takeover activity has been characterized by broader participation in acquiror financing on both debt and equity sides. We focus on private equity buyouts, and investigate whether the number of financing participants is related to the likelihood of insider trading prior to the bid announcement. Results suggest that more insiders leads to more insider trade. We study stock, option, bond, and CDS markets. Suspicious stock and options activity is associated with more equity participants, while suspicious activity in the credit markets is associated with more debt participants. The results highlight an important channel in the flow of information and may be consistent with models of limited competition among informed insiders. They are unlikely to be consistent with models of optimal regulation.
{"title":"More Insiders, More Insider Trading: Evidence from Private Equity Buyouts","authors":"V. Acharya, Timothy C. Johnson","doi":"10.2139/ssrn.1072703","DOIUrl":"https://doi.org/10.2139/ssrn.1072703","url":null,"abstract":"Recent takeover activity has been characterized by broader participation in acquiror financing on both debt and equity sides. We focus on private equity buyouts, and investigate whether the number of financing participants is related to the likelihood of insider trading prior to the bid announcement. Results suggest that more insiders leads to more insider trade. We study stock, option, bond, and CDS markets. Suspicious stock and options activity is associated with more equity participants, while suspicious activity in the credit markets is associated with more debt participants. The results highlight an important channel in the flow of information and may be consistent with models of limited competition among informed insiders. They are unlikely to be consistent with models of optimal regulation.","PeriodicalId":9906,"journal":{"name":"CEPR: Financial Economics (Topic)","volume":"76 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2007-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83978818","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 derives a tax-adjusted discount rate formula with a constant proportion leverage policy, investor taxes, and risky debt. The result depends on an assumption about the treatment of tax losses in default. We identify the assumption that justifies the textbook approach of discounting interest tax shields at the cost of debt. We contrast this with an alternative assumption that leads to the Sick (1990) result that these should be discounted at the riskless rate. These two approaches represent polar cases. Each generates its results by using a different simplifying assumption, and we explain what determines the correct treatment in practice. We also discuss implementation of the valuation procedure using the CAPM.
{"title":"Tax-Adjusted Discount Rates with Investor Taxes and Risky Debt","authors":"Ian A Cooper, Kjell G. Nyborg","doi":"10.2139/ssrn.605581","DOIUrl":"https://doi.org/10.2139/ssrn.605581","url":null,"abstract":"This paper derives a tax-adjusted discount rate formula with a constant proportion leverage policy, investor taxes, and risky debt. The result depends on an assumption about the treatment of tax losses in default. We identify the assumption that justifies the textbook approach of discounting interest tax shields at the cost of debt. We contrast this with an alternative assumption that leads to the Sick (1990) result that these should be discounted at the riskless rate. These two approaches represent polar cases. Each generates its results by using a different simplifying assumption, and we explain what determines the correct treatment in practice. We also discuss implementation of the valuation procedure using the CAPM.","PeriodicalId":9906,"journal":{"name":"CEPR: Financial Economics (Topic)","volume":"40 1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2007-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77795696","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 : 2005-10-01DOI: 10.7551/mitpress/9780262042543.003.0007
H. Huizinga
The EU deposit insurance directive requires member states to maintain deposit insurance with a minimum insured amount of 20,000 euros. This paper reviews the rationale for international coordination of deposit insurance policies. For international externalities of deposit insurance policies to exist, there has to be international ownership of either bank deposits or bank shares. On both counts, EU banking markets are currently highly integrated. The minimum coverage of 20,000 euros imposes costs if it forces some countries to 'overinsure' deposits. From a national perspective, the deposit insurance directive does not appear to result in overinsurance in the EU-15, but there may be overinsurance in several of the new member states.
{"title":"The EU Deposit Insurance Directive: Does One Size Fit All?","authors":"H. Huizinga","doi":"10.7551/mitpress/9780262042543.003.0007","DOIUrl":"https://doi.org/10.7551/mitpress/9780262042543.003.0007","url":null,"abstract":"The EU deposit insurance directive requires member states to maintain deposit insurance with a minimum insured amount of 20,000 euros. This paper reviews the rationale for international coordination of deposit insurance policies. For international externalities of deposit insurance policies to exist, there has to be international ownership of either bank deposits or bank shares. On both counts, EU banking markets are currently highly integrated. The minimum coverage of 20,000 euros imposes costs if it forces some countries to 'overinsure' deposits. From a national perspective, the deposit insurance directive does not appear to result in overinsurance in the EU-15, but there may be overinsurance in several of the new member states.","PeriodicalId":9906,"journal":{"name":"CEPR: Financial Economics (Topic)","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84138957","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}
Consider a non-spanned security $C_{T}$ in an incomplete market. We study the risk/return tradeoffs generated if this security is sold for an arbitrage-free price $hat{C_{0}}$ and then hedged. We consider recursive "one-period optimal" self-financing hedging strategies, a simple but tractable criterion. For continuous trading, diffusion processes, the one-period minimum variance portfolio is optimal. Let $C_{0}(0)$ be its price. Self-financing implies that the residual risk is equal to the sum of the one-period orthogonal hedging errors, $sum_{tleq T} Y_{t}(0) e^{r(T -t)}$. To compensate the residual risk, a risk premium $y_{t}Delta t$ is associated with every $Y_{t}$. Now let $C_{0}(y)$ be the price of the hedging portfolio, and $sum_{tleq T}(Y_{t}(y)+y_{t}Delta t)e^{r(T-t)}$ is the total residual risk. Although not the same, the one-period hedging errors $Y_{t}(0) and Y_{t}(y)$ are orthogonal to the trading assets, and are perfectly correlated. This implies that the spanned option payoff does not depend on y. Let $hat{C_{0}}-C_{0}(y)$. A main result follows. Any arbitrage-free price, $hat{C_{0}}$, is just the price of a hedging portfolio (such as in a complete market), $C_{0}(0)$, plus a premium, $hat{C_{0}}-C_{0}(0)$. That is, $C_{0}(0)$ is the price of the option's payoff which can be spanned, and $hat{C_{0}}-C_{0}(0)$ is the premium associated with the option's payoff which cannot be spanned (and yields a contingent risk premium of sum $y_{t}Delta$t$ e^{r(T-t)}$ at maturity). We study other applications of option-pricing theory as well.
考虑不完全市场中的非跨越证券$C_{T}$。我们研究产生的风险/回报权衡，如果这种证券以无套利价格$hat{C_{0}}$出售，然后对冲。我们考虑递归的“单期最优”自融资对冲策略，这是一个简单但易于处理的准则。对于连续交易、扩散过程，单周期最小方差组合是最优的。让$C_{0}(0)$成为它的代价。自融资意味着剩余风险等于一期正交套期误差的总和$sum_{tleq T} Y_{t}(0) e^{r(T -t)}$。为了补偿剩余风险，风险溢价$y_{t}Delta t$与每个$Y_{t}$相关联。现在设$C_{0}(y)$为对冲组合的价格，$sum_{tleq T}(Y_{t}(y)+y_{t}Delta t)e^{r(T-t)}$为总剩余风险。虽然不相同，但一期对冲误差$Y_{t}(0) and Y_{t}(y)$与交易资产是正交的，并且是完全相关的。这意味着跨越期权的收益不依赖于y。设$hat{C_{0}}-C_{0}(y)$。主要结果如下。任何无套利价格$hat{C_{0}}$就是对冲投资组合的价格$C_{0}(0)$加上溢价$hat{C_{0}}-C_{0}(0)$(比如在一个完整的市场中)。也就是说，$C_{0}(0)$是可以跨越的期权支付的价格，$hat{C_{0}}-C_{0}(0)$是与不可跨越的期权支付相关的溢价(到期时产生的或有风险溢价为$y_{t}Delta$ t $ e^{r(T-t)}$)。我们还研究了期权定价理论的其他应用。
{"title":"Option-Pricing in Incomplete Markets: The Hedging Portfolio Plus a Risk Premium-Based Recursive Approach","authors":"Alfredo Ibáñez","doi":"10.2139/ssrn.674622","DOIUrl":"https://doi.org/10.2139/ssrn.674622","url":null,"abstract":"Consider a non-spanned security $C_{T}$ in an incomplete market. We study the risk/return tradeoffs generated if this security is sold for an arbitrage-free price $hat{C_{0}}$ and then hedged. We consider recursive \"one-period optimal\" self-financing hedging strategies, a simple but tractable criterion. For continuous trading, diffusion processes, the one-period minimum variance portfolio is optimal. Let $C_{0}(0)$ be its price. Self-financing implies that the residual risk is equal to the sum of the one-period orthogonal hedging errors, $sum_{tleq T} Y_{t}(0) e^{r(T -t)}$. To compensate the residual risk, a risk premium $y_{t}Delta t$ is associated with every $Y_{t}$. Now let $C_{0}(y)$ be the price of the hedging portfolio, and $sum_{tleq T}(Y_{t}(y)+y_{t}Delta t)e^{r(T-t)}$ is the total residual risk. Although not the same, the one-period hedging errors $Y_{t}(0) and Y_{t}(y)$ are orthogonal to the trading assets, and are perfectly correlated. This implies that the spanned option payoff does not depend on y. Let $hat{C_{0}}-C_{0}(y)$. A main result follows. Any arbitrage-free price, $hat{C_{0}}$, is just the price of a hedging portfolio (such as in a complete market), $C_{0}(0)$, plus a premium, $hat{C_{0}}-C_{0}(0)$. That is, $C_{0}(0)$ is the price of the option's payoff which can be spanned, and $hat{C_{0}}-C_{0}(0)$ is the premium associated with the option's payoff which cannot be spanned (and yields a contingent risk premium of sum $y_{t}Delta$t$ e^{r(T-t)}$ at maturity). We study other applications of option-pricing theory as well.","PeriodicalId":9906,"journal":{"name":"CEPR: Financial Economics (Topic)","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2005-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82703988","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 investigates the link between a firm’s competitive environment and the idiosyncratic volatility of its stock returns. We find that firms enjoying high market power, or established in concentrated industries, have lower idiosyncratic volatility. We posit that competition affects volatility in two distinct and inter-related ways. Market power works as a hedging instrument that smoothes out idiosyncratic fluctuations. At the same time, a high degree of market power implies lower information uncertainty for investors and therefore lower return volatility. We find strong support for both effects. Our results contribute to the understanding of recent trends of idiosyncratic volatility, and confirm the important link between stock market performance and the competitive environment of firms.
{"title":"Idiosyncratic Volatility and Product Market Competition","authors":"José-Miguel Gaspar, M. Massa","doi":"10.1086/505251","DOIUrl":"https://doi.org/10.1086/505251","url":null,"abstract":"This Paper investigates the link between a firm’s competitive environment and the idiosyncratic volatility of its stock returns. We find that firms enjoying high market power, or established in concentrated industries, have lower idiosyncratic volatility. We posit that competition affects volatility in two distinct and inter-related ways. Market power works as a hedging instrument that smoothes out idiosyncratic fluctuations. At the same time, a high degree of market power implies lower information uncertainty for investors and therefore lower return volatility. We find strong support for both effects. Our results contribute to the understanding of recent trends of idiosyncratic volatility, and confirm the important link between stock market performance and the competitive environment of firms.","PeriodicalId":9906,"journal":{"name":"CEPR: Financial Economics (Topic)","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79270457","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 : 2004-07-01DOI: 10.1111/J.1540-6261.2005.00823.X
Gastón Gelos, S. Wei
Does country transparency affect international portfolio investment? We examine this question by constructing new measures of transparency and by making use of a unique micro dataset on portfolio holdings of emerging market funds around the world. We distinguish between government and corporate transparency. There is clear evidence that funds invest systematically less in less transparent countries. There is also some evidence that during crises, funds flee from non-transparent countries to a greater extent.
{"title":"Transparency and International Portfolio Holdings","authors":"Gastón Gelos, S. Wei","doi":"10.1111/J.1540-6261.2005.00823.X","DOIUrl":"https://doi.org/10.1111/J.1540-6261.2005.00823.X","url":null,"abstract":"Does country transparency affect international portfolio investment? We examine this question by constructing new measures of transparency and by making use of a unique micro dataset on portfolio holdings of emerging market funds around the world. We distinguish between government and corporate transparency. There is clear evidence that funds invest systematically less in less transparent countries. There is also some evidence that during crises, funds flee from non-transparent countries to a greater extent.","PeriodicalId":9906,"journal":{"name":"CEPR: Financial Economics (Topic)","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2004-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90639112","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：