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   21844篇
  免费   609篇
各国政治   916篇
工人农民   855篇
世界政治   1833篇
外交国际关系   772篇
法律   13161篇
中国共产党   2篇
中国政治   124篇
政治理论   4601篇
综合类   189篇
  2020年   267篇
  2019年   338篇
  2018年   441篇
  2017年   483篇
  2016年   520篇
  2015年   346篇
  2014年   432篇
  2013年   2176篇
  2012年   524篇
  2011年   564篇
  2010年   443篇
  2009年   501篇
  2008年   581篇
  2007年   595篇
  2006年   559篇
  2005年   505篇
  2004年   524篇
  2003年   523篇
  2002年   462篇
  2001年   923篇
  2000年   835篇
  1999年   662篇
  1998年   353篇
  1997年   306篇
  1996年   246篇
  1995年   249篇
  1994年   282篇
  1993年   252篇
  1992年   432篇
  1991年   484篇
  1990年   434篇
  1989年   438篇
  1988年   407篇
  1987年   439篇
  1986年   415篇
  1985年   410篇
  1984年   363篇
  1983年   391篇
  1982年   302篇
  1981年   297篇
  1980年   208篇
  1979年   309篇
  1978年   201篇
  1977年   163篇
  1976年   148篇
  1975年   154篇
  1974年   174篇
  1973年   167篇
  1972年   141篇
  1971年   122篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
In many states, legal representation for parents of dependent children is inadequate and can be a source of delays in securing permanency for children and unnecessarily protracted court proceedings. Often, such parents also face barriers to accessing services and independent evaluators. These issues are being addressed in the state of Washington through two approaches. The first is a successful enhanced legal representation program that has substantially improved case outcomes. The second is a statewide committee using innovative means to examine systemic responses to the challenges of the Adoption and Safe Families Act.  相似文献   
22.
23.
This paper reports results of a study based on a nationally representative sample of U.S. youth (N = 11,549) that asked two questions: (1) How does family structure affect the likelihood of adolescent death beyond that of race/ethnicity, sex, socioeconomic status, personal behavior, and other structural factors and (2) under what conditions might appeals for social justice be warranted for relative mortality statuses and for absolute gains in mortality? The study found that marital instability increases the likelihood of dying when controlling for a variety of other factors including class, race/ethnicity, sex, and unemployment rate in area of residence. The author argues that this finding lends support to social justice arguments to redistribute resources in such a way as to ensure the likelihood of absolute gains in mortality. The study also found, however, that race/ethnicity/sex also accounted for the likelihood of dying independently of family structure when controlling for socioeconomic and other factors. The author argues that this finding lends support to social justice arguments to redistribute resources on the basis of relative mortality statuses.  相似文献   
24.
Fibres used in forensic casework suffer from a disadvantage common to other forms of trace evidence--it is not possible to state with absolute certainty that they originate from a specific source. Target fibre studies, population studies and research on 'blocks of colour' have effectively demonstrated the polymorphism of textile fibres (particularly man-made ones) and have shown that when a fibre is believed to have a specific putative source, the chance that it has originated from a different source purely by coincidence is extremely remote. A study by Houck MM (Houck MM, Inter-comparison of unrelated fibre evidence. Forensic Science International 2003; 135: 146-149) has shown that no coincidental matching fibres were recovered from items of clothing examined in 20 unrelated crimes. The study involved over two million comparisons. This work goes a step further, and using the example of blue polyester fibres shows that even within a very narrow segment of the whole general fibre population, many examples of a specific colour/type of man-made fibre taken from random sources can be compared and the chance of any two being the same is very low. These studies should help to show the specificity and value of transferred fibres in providing forensic evidence.  相似文献   
25.
26.
27.
28.
Das Bundesverwaltungsgericht hat in seinem Urteil vom 16.3.2006 zum Gro?flughafen Berlin-Brandenburg in einem Leitsatz festgestellt, dass das FFH-Schutzregime, dem bestimmte Biotope unterliegen, sich nicht auf V?gel erstreckt, denen das betreffende Biotop als Habitat dient. Diese Feststellung führt zu der Frage, inwieweit charakteristische Arten von Lebensr?umen nach Anhang I FFH-RL in der FFH-Vertr?glichkeitsprüfung nach § 34 BNatSchG überhaupt bewertungsrelevant sind. Der Beitrag setzt sich dazu mit dem Urteil kritisch auseinander.  相似文献   
29.
30.
A method has been developed on reverse phase high performance liquid chromatography for simultaneous determination of methyl, ethyl and isopropyl alcohols under refractive index detection using pure water as the mobile phase. A good separation has been achieved between these alcohols. Detector response was linear with a detection limit of 5 mg/100 ml. Recovery studies were performed by adding known amounts of methyl and ethyl alcohols to blood, lung and liver within the range 80–90%. The reproducibility of the results was always >90%. The quantitative distribution of methyl alcohol in postmortem body tissues and fluids has been reported in three cases of poisoning.  相似文献   
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