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   21945篇
  免费   1318篇
各国政治   1008篇
工人农民   944篇
世界政治   1641篇
外交国际关系   899篇
法律   13933篇
中国共产党   4篇
中国政治   153篇
政治理论   4544篇
综合类   137篇
  2023年   94篇
  2021年   122篇
  2020年   485篇
  2019年   523篇
  2018年   696篇
  2017年   713篇
  2016年   799篇
  2015年   602篇
  2014年   661篇
  2013年   2623篇
  2012年   569篇
  2011年   635篇
  2010年   646篇
  2009年   689篇
  2008年   638篇
  2007年   644篇
  2006年   667篇
  2005年   561篇
  2004年   568篇
  2003年   469篇
  2002年   539篇
  2001年   771篇
  2000年   703篇
  1999年   561篇
  1998年   318篇
  1997年   246篇
  1996年   240篇
  1995年   255篇
  1994年   230篇
  1993年   234篇
  1992年   367篇
  1991年   374篇
  1990年   346篇
  1989年   326篇
  1988年   341篇
  1987年   320篇
  1986年   366篇
  1985年   372篇
  1984年   287篇
  1983年   276篇
  1982年   218篇
  1981年   208篇
  1980年   189篇
  1979年   262篇
  1978年   159篇
  1977年   118篇
  1976年   110篇
  1975年   120篇
  1974年   144篇
  1973年   103篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
The possible contribution of poppy seed foods to positive opiate urinalysis results, especially from foods available in the Pacific Rim area, has recently become an issue for the U.S. Army Forensic Toxicology Drug Testing Laboratory in Hawaii. To assess the likelihood of this possible contribution, seven different poppy seed food products were consumed by male and female volunteers, and urine specimens were collected at time increments up to either 24 or 72 h. Specimens were evaluated for opiates using Roche Abuscreen radioimmunoassay (RIA), and all RIA positive specimens were analyzed for morphine and codeine using gas chromatography/mass spectrometry (GC-MS). Poppy seed cake, bagels, muffins, and rolls did not contain sufficient quantities of poppy seeds to give rise to opiate positive specimens by U.S. Department of Defense (DOD) GC-MS cutoff levels (morphine = 4000 ng/mL, codeine = 2000 ng/mL), although a number of specimens were positive by National Institute on Drug Abuse (NIDA) cutoff levels (morphine and codeine = 300 ng/mL). However, ingestion of poppy seed streusel or Danish pastry led to confirmed morphine and codeine positive specimens, irrespective of the use of DOD or NIDA confirmation cutoff values. In addition, significant amounts of codeine were observed in a number of these specimens. These findings argue against the unqualified application of previously published quantitative guidelines for eliminating poppy seed ingestion as a possible cause for a positive opiate urinalysis result.  相似文献   
52.
53.
54.
Offender assessment and classification is becoming an increasingly important part of correctional supervision and intervention. Over the last several decades, several different methods and “generations” of offender classification have emerged. Of most value appear to be third-generation, actuarial, dynamic risk/need assessments. With any new correctional strategy, however, there is a need to investigate the use of these risk/need assessments on offender subgroups in order to inform issues, such as reliability and prevalence of criminogenic risk factors. The present study utilized data that were gathered using the Level of Service Inventory-Revised (LSI-R). Results and comparisons of these assessments were investigated and presented for Native American and non-Native American offenders as well as male and female offenders. Discussion of the results, implications, and recommendations for further research are presented.  相似文献   
55.
The most ferocious debates are about whether the United States should be described as imperial, but in practice other countries also try to influence other countries’ domestic policies, to propagate their visions, to exert power and to stabilize areas beyond their borders that are perceived as a source of threats. While in the 1990s the winners of globalization were seen as small open states, since the turn of the millennium big powers appear to be gaining because of their ability to project political power: the United States, but also China, Russia, India, and Brazil. This makes for a greater instability and leads to the formulation of theories of realism or neo-realism. The essay concludes with an examination of alternatives to empire and the neo-imperial vision, in particular the importance of elaboration of common or shared values in helping to build a safer and more peaceful international order.  相似文献   
56.
57.
58.
59.
A minisatellite probe, MZ 1.3, detecting hypervariable fragment patterns was isolated from a human genomic library. A repetitive sequence of 27 bp length was identified which is contained in the probe approx. 40 times. The MZ 1.3 repeat shows variable homology of 53-73% to the repetitive sequence of the protein III gene of the bacteriophage M13 genome. Polymorphic restriction fragment patterns were found with MZ 1.3 using the enzymes Hinf I, BstN I, Hae III, Mbo I, PstI/Pvu II, and Rsa I. An average of 18 polymorphic fragments was observed using Hinf I as enzyme. The band sharing frequency after Hinf I digestion among unrelated individuals was determined to be 23.8 +/- 7.2%. An example for the application of MZ 1.3 to paternity testing in an incest case is given. The probe can be used with radioactive or non-radioactive detection systems. An approach is presented to compare polymorphic fragment patterns from individuals obtained by independent gel runs on the basis of relative band positions (RBP) and calculated in a computerized analysis.  相似文献   
60.
Good gas chromatography (GC) separation of molecules is essential for clean gas chromatography/mass spectrometry (GC/MS) confirmation of compounds. The trifluoro derivatives of ephedrine (E) and methamphetamine (MA) coelute on dimethyl silicone capillary columns, such as DB-1, which are most commonly used by chromatographers. Methods are described to separate E and MA to aid GC/MS confirmations of methamphetamine, ephedrine, or both E and MA together, whichever may be present in Enzyme Immunoassay (EIA)-analyzed amphetamine-positive urine samples. The use of the heptafluoro derivatives of E and MA on a DB-1 column, or the trifluoro derivatives of E and MA on a DB-17 column, is suggested for good gas chromatographic separation.  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