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   22873篇
  免费   895篇
各国政治   998篇
工人农民   843篇
世界政治   1834篇
外交国际关系   783篇
法律   14218篇
中国共产党   2篇
中国政治   106篇
政治理论   4779篇
综合类   205篇
  2020年   343篇
  2019年   389篇
  2018年   477篇
  2017年   560篇
  2016年   589篇
  2015年   456篇
  2014年   493篇
  2013年   2309篇
  2012年   531篇
  2011年   570篇
  2010年   510篇
  2009年   566篇
  2008年   572篇
  2007年   592篇
  2006年   572篇
  2005年   522篇
  2004年   540篇
  2003年   530篇
  2002年   489篇
  2001年   900篇
  2000年   808篇
  1999年   682篇
  1998年   363篇
  1997年   300篇
  1996年   267篇
  1995年   274篇
  1994年   314篇
  1993年   294篇
  1992年   455篇
  1991年   484篇
  1990年   435篇
  1989年   469篇
  1988年   415篇
  1987年   452篇
  1986年   434篇
  1985年   443篇
  1984年   368篇
  1983年   403篇
  1982年   320篇
  1981年   303篇
  1980年   223篇
  1979年   335篇
  1978年   231篇
  1977年   191篇
  1976年   175篇
  1975年   161篇
  1974年   182篇
  1973年   162篇
  1972年   147篇
  1971年   121篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
161.
In this study, a new method was developed for the impurity profiling of illicit MDMA tablets. The extraction efficiency, linearity, repeatability and reproducibility of the method were evaluated. Eighty two MDMA tablets coming from presumed unrelated large seizures in 2004 (n >500 tablets) were analyzed by gas chromatography mass spectrometry (GC-MS) in order to assess the discrimination power of the method. The latter was found to be practical, robust, relatively easy to perform, highly discriminative and yielding good chromatography. In addition, some new impurities were detected and identified. Their chemical structures and mass spectra are reported.  相似文献   
162.
163.
The increased risk of child maltreatment in the presence of domestic violence is well documented, but much remains unknown about factors that modify this relationship. This study investigates the roles of risk and protective factors in the relationship between domestic violence and being reported to the Department of Social Services for child maltreatment. Consistent with the literature, we find a significant overlap between domestic violence and maltreatment. Young maternal age, low education, low income, and lack of involvement in a religious community add to the risk for maltreatment associated with domestic violence. Separation between the maternal caregiver and her partner significantly reduces the risk for maltreatment when domestic violence is reported. A significant reduction in the risk for maltreatment is also found with higher levels of support from the maternal caregiver reported by the child in the context of domestic violence.  相似文献   
164.
In a case of suicidal application of electricity differences between the rectal temperature of the body and the suspected time of death were observed.In order to answer the question whether an electric current from hand to hand over >30 min led to a rise in body temperature FEM-based computer simulations and animal experiments were carried out. Both resulted in a warming of the soft parts in the arm without warming the body core. Thus a temperature-based estimation of the time since death can also be used in cases with electricity as the cause of death. Besides, in the animal experiment we found a spontaneous rise in the body core temperature even without application of electricity which may be a reason for the typical temperature plateau after death.  相似文献   
165.
166.
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   
167.
Conducting child custody evaluations is one of the most complex, challenging, and sometimes risky professional endeavors that a mental health professional can perform. This article examines the professional and personal challenges which may be encountered by the evaluator. In addition to discussing the role requirements and need to maintain awareness of bias and countertransference, challenges such as coping with state board or ethics complaints and possible risks to personal safety are also addressed. Suggestions for risk management and coping with the demands of these assessments are offered, as well as the benefits and rewards of engaging in this important work.  相似文献   
168.
169.
170.
More than a decade after NAFTA (North American Free Trade Agreement) entered into force, the environmental effects of agricultural trade liberalization in Mexico are still controversial, emerging, and not fully understood. This paper contributes to the literature that aims to explore trends in input use in the agricultural sector in Mexico during the post-NAFTA period among both commercial/industrial and traditional/rainfed farmers, and examines the influence of the national and multilateral institutional framework on these outcomes. We decompose the post-NAFTA agricultural production data into scale, technique and composition effects to estimate the impact that trade liberalization has had on the use of fertilizer and land use, two key agricultural inputs for which reliable aggregate data is available. We conclude that among commercial farmers patterns of crop type specialization and significant technological improvements have led to some declines in fertilizer use but they have been offset by growth in fertilizer use associated with growing agricultural output. Among traditional farmers increased output and specialization in land-intensive grain crops are contributing to an increase in land under cultivation and technological improvements show the potential, but not yet not the strength, to counteract these effects. We analyse the environmental institutional framework and rural development plans, observing that institutional weaknesses have, in several instances, reduced the environmental benefit of technique and composition effects. We conclude with recommendations about how the Mexican agricultural sector might reap the environmental benefits of international agricultural trade.  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