全文获取类型
收费全文 | 6048篇 |
免费 | 142篇 |
专业分类
各国政治 | 263篇 |
工人农民 | 278篇 |
世界政治 | 487篇 |
外交国际关系 | 222篇 |
法律 | 3741篇 |
中国政治 | 53篇 |
政治理论 | 1126篇 |
综合类 | 20篇 |
出版年
2021年 | 43篇 |
2020年 | 88篇 |
2019年 | 114篇 |
2018年 | 147篇 |
2017年 | 132篇 |
2016年 | 129篇 |
2015年 | 81篇 |
2014年 | 132篇 |
2013年 | 634篇 |
2012年 | 155篇 |
2011年 | 159篇 |
2010年 | 131篇 |
2009年 | 157篇 |
2008年 | 183篇 |
2007年 | 166篇 |
2006年 | 150篇 |
2005年 | 141篇 |
2004年 | 166篇 |
2003年 | 132篇 |
2002年 | 110篇 |
2001年 | 314篇 |
2000年 | 280篇 |
1999年 | 194篇 |
1998年 | 80篇 |
1997年 | 83篇 |
1996年 | 52篇 |
1995年 | 56篇 |
1994年 | 53篇 |
1993年 | 43篇 |
1992年 | 122篇 |
1991年 | 142篇 |
1990年 | 134篇 |
1989年 | 127篇 |
1988年 | 113篇 |
1987年 | 126篇 |
1986年 | 101篇 |
1985年 | 96篇 |
1984年 | 101篇 |
1983年 | 83篇 |
1982年 | 61篇 |
1981年 | 75篇 |
1980年 | 34篇 |
1979年 | 74篇 |
1978年 | 44篇 |
1975年 | 37篇 |
1974年 | 50篇 |
1973年 | 54篇 |
1972年 | 39篇 |
1971年 | 34篇 |
1970年 | 29篇 |
排序方式: 共有6190条查询结果,搜索用时 15 毫秒
51.
Deoxyribonucleic acid (DNA) typing of ribosomal ribonucleic acid (rRNA) genes was performed with a polymerase chain reaction (PCR) assay for species identification. A variable region of the 28S ribosomal RNA gene was amplified with primers complementary to flanking sequences phylogenetically well conserved. The products of twelve animal DNAs (human, Japanese monkey, dog, cattle, pig, cat, rabbit, mouse, rat, chicken, frog, and fish) were separated by polyacrylamide gel electrophoresis, each revealing a few bands ranging from 150 to 100 base pairs. The band patterns obtained from each DNA sample differed in number and size, which indicates the applicability of the method to species identification. Samples containing either as little as 1 pg of DNA or degraded DNA of 0.2 to 0.5 kb in length were able to give detectable bands. Postmortem human tissue DNAs were tested as an example. They showed a pattern identical to the human control one, which was distinct from those of the other animals examined. 相似文献
52.
N C Martin A A Pirie L V Ford C L Callaghan K McTurk D Lucy D G Scrimger 《Science & justice》2006,46(3):179-184
In the forensic science laboratory, the recovery of spermatozoa from vaginal swabs, or vaginal cells from penile swabs, can help determine if sexual intercourse may have taken place. There are several methods used to recover spermatozoa and cells from the swabs before visualisation on a microscope slide and most of these methods use water. Phosphate buffered saline (PBS) is a non-toxic solution used in many biological laboratories. Unlike water, PBS prevents cells rupturing or shrivelling up due to osmosis. This study demonstrates that PBS can be used for the extraction of spermatozoa and cells from swabs and that PBS does not affect subsequent DNA profiling. 相似文献
53.
The 2003 Duma election resulted in the victory of the party of power, thereby strengthening managed democracy in Russia. Since then, political trends in Russia's regions and rural politics provide considerable evidence of the increasing ability of pro-Kremlin forces to maximise their electoral fortunes in national contests. These political trends make it likely that United Russia will not only emerge as the dominant party in the 2007 Duma election, but will provide the Kremlin and Putin's successor with a compliant lower house. The outcome is that Putin's successor will find the political infrastructure to continue managed democracy. 相似文献
54.
Netherlands International Law Review - 相似文献
55.
K Lalu P J Karhunen P Rautiainen 《The American journal of forensic medicine and pathology》1992,13(3):196-198
A 6-month-old girl died suddenly without any previous symptoms of heart failure. Autopsy examination showed cardiomegaly (97 g) with a severely fibrotized myocardium. The left coronary artery was originating from the pulmonary artery. Histologically, the myocardium showed myocardial infarcts of different ages, as well as grossly thickened arterial branches due to increased flow in left-right shunt. We suggest that rare anomalies of the coronary arteries should be considered in the autopsies of suspected sudden infant death syndrome cases. 相似文献
56.
K. Michael Reynolds Pamala L. Griset Ernest Scott 《American Journal of Criminal Justice》2006,31(1):1-17
Many attempts have been made over the last several decades to improve communication among law enforcement agencies. This article
is a case study of a “low-level” data sharing project in Florida that could serve as a national model. The Florida Law Enforcement
Data Sharing Consortium is a partnership between the University of Central Florida and more than one hundred law enforcement
agencies. It offers an inexpensive, yet technically advanced alternative to the proprietary data sharing model. Its distributed
architecture was endorsed by the Markle Foundation, the 9/11 Commission, and the 2004 National Security Act. Civil liberties
concerns raised by this and other types of data sharing projects are discussed. 相似文献
57.
U.S. Supreme Court Justice Thurgood Marshall offered his opinion regarding the utility of public opinion polls as a tool for assessing the “evolving standards of decency” regarding capital punishment. His arguments became known as the Marshall hypotheses and spawned a considerable body of empirical testing. The three Marshall hypotheses are: (1) support for capital punishment is inversely associated with knowledge about it, (2) exposure to information about capital punishment produces sentiments in opposition to capital punishment, but (3) exposure to information about capital punishment will have no impact on those who support it for retributive reasons. The results of previous tests of these hypotheses were somewhat mixed but supportive. None of these studies, however, examined the effects of change in knowledge levels with changes, if any, in death penalty attitudes and beliefs as needed for a more complete test of the Marshall hypotheses. The present study addressed this shortcoming. The results provided mixed support for these three hypotheses. That is, death penalty supporters were somewhat less informed than death penalty opponents; exposure to death penalty information and knowledge gains tended to be associated with attitudinal change in a directions suggested by these hypotheses; but, retributivists' attitudes toward and beliefs about capital punishment were not any more resistant to change than were the attitudes and beliefs of non-retributivists. 相似文献
58.
重新审视研究了国外援助及其他因素对加纳经济增长的意义和影响。自加纳共和国独立以来,外商通过不同的渠道在加纳进行投资,目前约占国家预算的40%。那么,这些来自发达国家的资源是否对加纳的经济发展产生了积极的影响呢?为了解决这一难题,运用简单的最小二乘法(OLS),选取了包括国外援助在内的5个独立变量对加纳26年的经济增长进行了回归运算。其中,经济的波动体现在加纳1982年到2007年之间国内生产总值(GDP)的变化上。文中数据取自历年相关书籍,经合组织档案与公共文献。本文的研究证明,国外援助是一国经济增长的重要决定因素。数据显示,国外援助在1982年至2007年的26年里对加纳的经济增长产生了重大而积极的影响。 相似文献
59.
60.
Using merged administrative data from welfare reform evaluations in three states, we estimate the effects of child care subsidy use on the length of time it takes for a welfare applicant to move into substantial employment. Findings show that the use of a child care subsidy during an unemployed or marginally employed spell of welfare receipt is associated with between a 0.6 and 1.7 quarter (or 11% to 34%) reduction in the time to substantial employment in two of the three state samples. The positive influence of subsidy use on transitions to substantial employment is strongest for those welfare applicants with the lowest earnings who are mixing welfare and work prior to subsidy receipt. 相似文献