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   7695篇
  免费   136篇
各国政治   177篇
工人农民   730篇
世界政治   352篇
外交国际关系   278篇
法律   4843篇
中国政治   24篇
政治理论   1404篇
综合类   23篇
  2023年   37篇
  2020年   59篇
  2019年   77篇
  2018年   517篇
  2017年   524篇
  2016年   429篇
  2015年   84篇
  2014年   93篇
  2013年   415篇
  2012年   196篇
  2011年   473篇
  2010年   509篇
  2009年   367篇
  2008年   386篇
  2007年   389篇
  2006年   124篇
  2005年   99篇
  2004年   136篇
  2003年   134篇
  2002年   89篇
  2001年   208篇
  2000年   208篇
  1999年   149篇
  1998年   63篇
  1997年   65篇
  1996年   64篇
  1995年   75篇
  1994年   75篇
  1993年   52篇
  1992年   118篇
  1991年   106篇
  1990年   132篇
  1989年   121篇
  1988年   136篇
  1987年   129篇
  1986年   100篇
  1985年   106篇
  1984年   86篇
  1983年   79篇
  1982年   56篇
  1981年   47篇
  1980年   40篇
  1979年   56篇
  1978年   38篇
  1977年   27篇
  1976年   30篇
  1975年   28篇
  1974年   39篇
  1973年   29篇
  1970年   27篇
排序方式: 共有7831条查询结果,搜索用时 15 毫秒
31.
Blood previously acidified with aqueous saturated ammonium chloride solution was extracted with ethyl acetate. The dried extract was subjected to acetonitrile–hexane partition. The acetonitrile portion was analysed for the presence of acidic and neutral drugs by HPLC–DAD (200 mm×2.1 mm I.D. microbore ODS-Hypersil column) and GC–FID (25 m narrow-bore×0.25 mm I.D. HP-5 column with 0.33 μm film thickness). The protocol was found to be suitable for both clinical toxicology (including emergency toxicology) and postmortem toxicology. At least 66 drugs of interest were unequivocally identified by RRTs (HPLC) and UV spectra (DAD) match while another 12 were unequivocally identified by double RRTs match (HPLC and GC). Quantitation was facilitated by incorporating calibration blood standards in each assay batch. The five drugs most commonly encountered in clinical blood specimens (1150 cases) were: paracetamol (47.4% of the cases); chlormezanone (6.6%), theophylline (1.74%), naproxen (1.65%) and mefenamic acid (1.56%). The following drugs were detected in toxicologically significant quantities in postmortem blood specimens (245 cases): phenobarbitone (1.22% of the cases), naproxen (0.82%), chlormezanone (0.82%), theophylline (0.82%), carbamazepine (0.41%) and paracetamol (0.41%).  相似文献   
32.
33.
The enzyme activity of phosphoglucomutase (PGM) has been investigated in red cell haemolysates from 142 individuals and compared to the sub-type as determined by isoelectric focusing. The 10 phenotypes showed significant differences in PGM-activity which indicates that there is a correlation between the level of activity and the isolelectric point of homozygotes. No indication of silent alleles or alleles with reduced activity was found in this collective.  相似文献   
34.
The Green River Murder Investigation in King County, Washington, is currently the longest active serial murder investigation in U.S. history. During its course, over 26 separate scenes with from one to five victims each have been processed. The experience of the authors is presented in order to acquaint other agencies with techniques of outdoor scene processing that have evolved during recovery of remains from Green River and other skeletal cases.  相似文献   
35.
36.
37.
The population-adjusted rate of teenage suicide in King County, Washington, was reviewed for the 26 years from 1959 to 1984. For the entire period, the rate did not change significantly. An abrupt change did occur during the middle of this period, but, for reasons discussed in the text, this may well represent a change in procedures and philosophy of death certification rather than a real change in rate. Reasons for the apparent discrepancy with national statistics are discussed.  相似文献   
38.
39.
40.
In the wake of the 1990 amendments to the Clean Air Act, localities across the United States initiated public information campaigns both to raise awareness of threats to air quality and to change behavior related to air pollution by recommending specific behavioral changes in the campaign messages. These campaigns are designed to reduce the health hazards associated with poor air quality and to avoid federal sanctions resulting from the failure to meet air quality standards. As in many other communities across the country, a coalition of government agencies and businesses initiated a public information campaign in the Atlanta metropolitan region to reduce certain targeted behaviors, mainly driving. A two‐stage model used to analyze data from a rolling sample survey shows that the centerpiece of the information campaign—air quality alerts—was effective in raising awareness and reducing driving in a segment of the population. When the overall information campaign was moderated by employers' participation in programs to improve air quality, drivers significantly reduced the number of miles they drove and the number of trips they took by car on days when air quality alerts were sounded. Public information campaigns can be successful in increasing awareness, but changing well‐established behaviors, such as driving, is likely to require institutional mediation to provide social contexts that support the behavioral change, as well. © 2003 by the Association for Public Policy Analysis and Management.  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