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   7152篇
  免费   237篇
各国政治   350篇
工人农民   292篇
世界政治   557篇
外交国际关系   268篇
法律   4241篇
中国政治   45篇
政治理论   1570篇
综合类   66篇
  2020年   94篇
  2019年   124篇
  2018年   174篇
  2017年   176篇
  2016年   176篇
  2015年   120篇
  2014年   142篇
  2013年   806篇
  2012年   160篇
  2011年   172篇
  2010年   166篇
  2009年   164篇
  2008年   177篇
  2007年   170篇
  2006年   189篇
  2005年   160篇
  2004年   148篇
  2003年   161篇
  2002年   152篇
  2001年   219篇
  2000年   182篇
  1999年   163篇
  1998年   99篇
  1997年   94篇
  1996年   72篇
  1995年   76篇
  1994年   74篇
  1993年   83篇
  1992年   117篇
  1991年   149篇
  1990年   131篇
  1989年   143篇
  1988年   130篇
  1987年   150篇
  1986年   139篇
  1985年   153篇
  1984年   138篇
  1983年   140篇
  1982年   101篇
  1981年   94篇
  1980年   91篇
  1979年   97篇
  1978年   76篇
  1977年   61篇
  1976年   66篇
  1975年   61篇
  1974年   74篇
  1973年   69篇
  1972年   56篇
  1969年   57篇
排序方式: 共有7389条查询结果,搜索用时 15 毫秒
31.
Correlation between plasma and bone marrow tricyclic antidepressants has not been studied before. Two groups of rabbits were given 10 and 20 mg of desipramine/kg body weight, respectively. Desipramine was administered to the animals once daily by mouth for 5 days. On the fifth day the animals were sacrificed and blood and bone marrow samples were collected and analyzed using a high performance liquid chromatographic (HPLC) method. Data showed that a correlation exists between bone marrow and blood desipramine. The bone marrow desipramine concentration increased as its blood levels increased. The average ratio of bone marrow to blood desipramine +/- S.D. (standard deviation) in both dosage groups was 37.2 +/- 4.46 with a range of 30.99-44.82. This investigation is promising and shows that bone marrow could be used as an alternative tissue in the absence of a suitable blood sample.  相似文献   
32.
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   
33.
This article reports on the results of a telephone survey conducted with a random sample of households screened for eligibility to receive child support in the state of Colorado. Despite the recent enactment of ambitious child legislation at the state and federal levels, the accounts of 731 custodial parents reveal a massive level of unmet need, with child support problems being most extreme for those never married to the chilďs other parent. These mothers typically lack an order establishing a legal obligation to pay child support and have incomes that fall below the poverty level. Overall, women of Colorado with child support orders received only about half of the support they were due, and 73 per cent of all women due support reported that they had experienced problems in collecting support either currently or in the past. The average amount of back due child support owed to the 60 per cent of women in the sample who reported an arrearage was $12,000. Analysis revealed that payment behaviour tracked with the length of time since separation with payment patterns worsening over time and irregular visitation and/or the presence of problems around child access. Female obligors exhibited the same payment patterns as their male counterparts but were more apt to maintain visitation. The article documents the dramatic, negative economic consequences of irregular or missing child support payments for custodial parents, and discusses the additional legal and financial commitments needed to improve the situation. The efficacy of private child support transfers to achieve an adequate standard of living for all children is called into question.  相似文献   
34.
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   
35.
In the statistical interpretation of forensic glass evidence it is standard practice to make the assumption of homogeneity of the refractive index (RI) of the source glass, or of localized homogeneity. However, the work of Locke and Hayes showed that, for toughened windscreen glass, this assumption might not be true. This work is well cited, but there appears to have been little follow-on published research. Furthermore, the toughening process is something known to affect the refractive index, and is a process that float glass does not undergo. Float glass is a major component of casework in New Zealand and for that reason it would be interesting to know whether the findings of Locke and Hayes apply when dealing with float glass. In this paper we describe an experiment similar to that of Locke and Hayes, systematically examining the variation of RI in a pane of float window glass. It was found that, although there were no systematic differences in refractive index, there were observable differences across the pane.  相似文献   
36.
37.
Report of an unusual finding of bones on the shore of the Baltic Sea. Although the morphological findings appeared similar to a human foot skeleton, a quick identification as sea dog bone was possible.  相似文献   
38.
A new solid-phase extraction procedure for the determination of cocaine and benzoylecgonine in amniotic fluid, using high flow co-polymeric sorbents is reported. The recoveries of cocaine and benzoylecgonine within the range 0.1-1 mg/l were 95.7% and 50.3%, respectively. The use of high-flow sorbents allowed the easy extraction of amniotic fluid regardless of sample viscosity or physical nature. The use of these solid-phase columns provided many advantages over the more commonly used solvent extraction, including an increase in extraction speed and efficiency, reduced operator time, reduced solvent use and disposal volumes and exceptional extract quality. Further, the determination of amniotic fluid obtained from pregnant cocaine users may provide important information about handling of cocaine by the fetus at various gestational ages. The procedure was successfully applied to amniotic fluid from suspected cocaine abusers.  相似文献   
39.
40.
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