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   13426篇
  免费   409篇
各国政治   675篇
工人农民   584篇
世界政治   858篇
外交国际关系   392篇
法律   8352篇
中国共产党   4篇
中国政治   85篇
政治理论   2776篇
综合类   109篇
  2020年   168篇
  2019年   208篇
  2018年   295篇
  2017年   329篇
  2016年   320篇
  2015年   243篇
  2014年   245篇
  2013年   1466篇
  2012年   362篇
  2011年   344篇
  2010年   294篇
  2009年   311篇
  2008年   390篇
  2007年   351篇
  2006年   383篇
  2005年   344篇
  2004年   351篇
  2003年   315篇
  2002年   320篇
  2001年   436篇
  2000年   414篇
  1999年   315篇
  1998年   185篇
  1997年   172篇
  1996年   149篇
  1995年   157篇
  1994年   149篇
  1993年   161篇
  1992年   271篇
  1991年   279篇
  1990年   269篇
  1989年   261篇
  1988年   242篇
  1987年   257篇
  1986年   273篇
  1985年   267篇
  1984年   226篇
  1983年   241篇
  1982年   146篇
  1981年   139篇
  1980年   118篇
  1979年   150篇
  1978年   129篇
  1977年   105篇
  1976年   94篇
  1975年   104篇
  1974年   119篇
  1973年   116篇
  1972年   101篇
  1969年   81篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
841.
This work presents a novel collection method for gunshot residues (GSR) using a sampling procedure based on ethylenediaminetetraacetic acid (EDTA) solution as a complexing agent on moistened swabs. Detection was via a sector-field inductively coupled plasma mass spectrometry (HRICP-MS). The proposed collection and analytical method allowed detection of antimony (Sb), barium (Ba) and lead (Pb) after .38 shot tests. at detection limits of less than 1 microg L(-1) in four different areas of the hands of volunteers. This paper includes a discussion concerning hand areas near the thumb and forefinger as being more suitable for GSR collection as well as a comparison between differences observed using 2% diluted EDTA. 2% nitric acid solution, and simple deionized water as collecting solutions, proving the superior efficiency of EDTA in GSR recoveries.  相似文献   
842.
843.
Zaleplon, a sedative-hypnotic, was identified in the blood of a subject arrested for impaired driving. Symptoms reported were those of central nervous system (CNS) depression. The zaleplon concentration was determined to be 0.13 microg/mL. Symptoms included slow movements and reactions, poor coordination, and lack of balance. Although no quantitative relationship between blood concentrations and degree of driving impairment is currently possible, it is reasonable to conclude that because of its specific activity as a sedative-hypnotic, blood concentrations consistent with doses exceeding therapeutic concentrations of zaleplon have the potential to cause impairment of psychomotor function, and would impair a person's level of consciousness and driving ability.  相似文献   
844.
845.
846.
A total of 743 lethal outcomes of thromboembolytic complications of trauma, diseases and certain pathological conditions as observed in 1999-2001 and in the three quarters of 2002 were studied. The undertaken analysis confirmed two factors provoking the pathological thrombosis, i.e. 1. Pathological changes observed in the surface vascular wall preconditioned by mechanical damages, atherosclerotic process and aging; and 2. A slower blood flow due to an impaired blood circulation, a forced positioning and to hypodynamics. While deciding on a possibility of a direct cause-effect relation between past traumas, surgeries, poisonings and death of thromboembolism of the pulmonary arteries (TEPA), such relation can be mentioned only on rare occasions. It is more often the case that an indirect, mediated relationship is found, when TERA evolves due to an unfavorable combination of risk factors, i.e. a forced immobility, changing coagulated blood system, impaired blood vessels etc.  相似文献   
847.
A possibility was studied to use the plaster copies of skulls in the forensic medical identification of personality by applying the craniofacial method. No dependence was found between the plaster casts and the moulding types. Differences between the same craniometric sizes in the skull and in its cast are of an incidental nature. Such incidental deviation is related with an accuracy of determining the localization of craniometric points and with an instrumental precision of measuring devices. The necessity is substantiated that, while making a craniofacial examination, it is necessary to mark all anthropometric points in the skull cast, with the original being a control. The use of a plaster skull cast is possible in those cases, when the burial of the remains must be done in full.  相似文献   
848.
849.
This article provides a new maximum-likelihood estimator forselection models with dichotomous dependent variables when identicalfactors affect the selection equation and the equation of interest.Such situations arise naturally in game-theoretic models whereselection is typically nonrandom and identical explanatory variablesinfluence all decisions under investigation. When identicalexplanatory variables influence selection and a subsequent outcomeof interest, the commonly used Heckman-type estimators identifyfrom distributional assumptions about the residuals alone. Whenits own identifying assumption is reasonable, the new estimatorallows the researcher to avoid the painful choice between identifyingfrom distributional assumptions alone and adding a theoreticallyunjustified variable to the selection equation in a mistakenattempt to "boost" identification. The article uses Monte Carlomethods to compare the small-sample properties of the estimatorwith those of the Heckman-type estimator and ordinary probit.  相似文献   
850.
Disability has high societal and personal costs. Various disparate federal and state programs attempt to address the economic and social needs of people with disabilities. Presumably workplace injuries and accidents are an important source of disability. Yet separate public policies and research literatures have evolved for these two social problems--disability and workplace injuries--despite their relatedness. This article seeks to document the overlap between these two phenomena in estimating the proportion of the disabled population whose disability was caused by workplace injury, accident, or illness using the Health and Retirement Study of 1992. The results point toward the need for initiatives to reduce disability that focus on work-related causes, which are a common pathway to disability, and that may result in substantial savings in federal programs.  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