首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   8923篇
  免费   566篇
各国政治   497篇
工人农民   284篇
世界政治   654篇
外交国际关系   391篇
法律   5728篇
中国政治   56篇
政治理论   1822篇
综合类   57篇
  2021年   48篇
  2020年   186篇
  2019年   220篇
  2018年   228篇
  2017年   276篇
  2016年   303篇
  2015年   250篇
  2014年   247篇
  2013年   1064篇
  2012年   211篇
  2011年   219篇
  2010年   260篇
  2009年   284篇
  2008年   229篇
  2007年   230篇
  2006年   241篇
  2005年   227篇
  2004年   228篇
  2003年   226篇
  2002年   200篇
  2001年   343篇
  2000年   299篇
  1999年   258篇
  1998年   144篇
  1997年   92篇
  1996年   101篇
  1995年   109篇
  1994年   107篇
  1993年   102篇
  1992年   172篇
  1991年   163篇
  1990年   165篇
  1989年   161篇
  1988年   144篇
  1987年   152篇
  1986年   128篇
  1985年   134篇
  1984年   108篇
  1983年   123篇
  1982年   87篇
  1981年   85篇
  1980年   60篇
  1979年   116篇
  1978年   72篇
  1977年   65篇
  1976年   51篇
  1975年   50篇
  1974年   57篇
  1973年   55篇
  1972年   44篇
排序方式: 共有9489条查询结果,搜索用时 31 毫秒
921.
A novel method for the forensic analysis of commercial petroleum products is presented. In this approach, the petroleum sample is extracted with nitromethane and then separated by capillary liquid chromatography with laser-induced fluorescence detection. The addition of selective fluorescence quenching agents allows the sample to be profiled by the distribution of alternant and nonalternant polycyclic aromatic hydrocarbons (PAHs). In preliminary studies, the quenching behavior of nitromethane and diisopropylamine was established by using a standard mixture of sixteen PAHs ranging in size from two to six aromatic rings. Subsequent examination of new and used motor oil demonstrated that characteristic differences arise in the PAH content, which may allow for the unique identification of oil from a particular engine or vehicle. In addition, three brands of petrolatum jelly were successfully distinguished. Although a number of alternant alkylated and heterocyclic PAHs were found in all petrolatum samples, there were significant differences in the relative concentrations of alternant as well as nonalternant PAHs. This allowed for clear differentiation of the samples through qualitative inspection of their chromatograms as well as quantitative statistical correlation techniques.  相似文献   
922.
923.
924.
925.
One long‐recognized consequence of the tension between popular sovereignty and democratic values like liberty and equality is public opinion backlash, which occurs when individuals recoil in response to some salient event. For decades, scholars have suggested that opinion backlash impedes policy gains by marginalized groups. Public opinion research, however, suggests that widespread attitude change that backlash proponents theorize is likely to be rare. Examining backlash against gays and lesbians using a series of online and natural experiments about marriage equality, and large‐sample survey data, we find no evidence of opinion backlash among the general public, by members of groups predisposed to dislike gays and lesbians, or from those with psychological traits that may predispose them to lash back. The important implication is that groups pursuing rights should not be dissuaded by threats of backlash that will set their movement back in the court of public opinion.  相似文献   
926.
927.
928.
Abstract

This paper provides a comprehensive evaluation of market segmentation and lender/purchaser specialization in the primary and secondary mortgage markets. It describes and assesses the 1990 Home Mortgage Disclosure Act (HMDA) data, which for the first time provide detailed information on the borrower and neighborhood racial and income characteristics of mortgage loan originations and securitizations in the primary and secondary mortgage markets. Evidence presented in the paper indicates that home purchase loan origination rates for black applicants—and, to a lesser degree, Hispanic applicants—appear to be significantly lower than those of other racial or ethnic groups. Similarly, the HMDA data reveal that home purchase mortgage origination rates in predominantly minority census tracts are significantly lower than those in predominantly white neighborhoods. The HMDA data also indicate a striking reliance of black borrowers on government‐backed forms of mortgage credit.

The paper further reveals that secondary market loan purchase distributions arrayed by borrower and neighborhood characteristics generally reflect those of home mortgage originations. The borrower and locational characteristics of home purchase loans acquired by the Government National Mortgage Association (GNMA) directly reflect that agency's legislated specialization in government‐backed loans, whereas the characteristics of loans acquired by Fannie Mae and Freddie Mac for the most part derive from the borrower and geographic composition of conventional home purchase loan originations. Findings of analyses of HMDA data raise concern regarding the access of minority and low‐income households and neighborhoods to mortgage finance. Those results also raise some question as to whether the federally chartered agencies in the secondary market are adequately promoting the availability of mortgage credit to low‐ and moderate‐income and minority households.  相似文献   
929.
930.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号