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   22111篇
  免费   712篇
  国内免费   5篇
各国政治   872篇
工人农民   926篇
世界政治   1502篇
外交国际关系   732篇
法律   14318篇
中国共产党   6篇
中国政治   191篇
政治理论   4080篇
综合类   201篇
  2020年   295篇
  2019年   359篇
  2018年   433篇
  2017年   517篇
  2016年   533篇
  2015年   386篇
  2014年   432篇
  2013年   2032篇
  2012年   589篇
  2011年   625篇
  2010年   519篇
  2009年   532篇
  2008年   630篇
  2007年   700篇
  2006年   676篇
  2005年   597篇
  2004年   594篇
  2003年   652篇
  2002年   552篇
  2001年   896篇
  2000年   765篇
  1999年   646篇
  1998年   316篇
  1997年   229篇
  1996年   271篇
  1995年   231篇
  1994年   265篇
  1993年   248篇
  1992年   430篇
  1991年   476篇
  1990年   449篇
  1989年   403篇
  1988年   428篇
  1987年   389篇
  1986年   423篇
  1985年   405篇
  1984年   334篇
  1983年   336篇
  1982年   257篇
  1981年   278篇
  1980年   190篇
  1979年   259篇
  1978年   188篇
  1977年   167篇
  1976年   145篇
  1975年   160篇
  1974年   177篇
  1973年   150篇
  1972年   133篇
  1971年   131篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
861.
862.
In the case of suspicious deaths, the technique of 1:1 taping is often used in Belgium. It consists of affixing a large number of adhesive tapes to the body of the victim. It is conventionally aimed at obtaining microtraces (e.g., fibers, hair) and is usually not used for DNA analysis. However, in some cases, DNA analysis of certain areas of interest identified on the 1:1 taping material can offer a last resort solution. The four-step method that is described in this article involves the selection of areas of interest on the body (Step 1), the selection of the corresponding tapes (Step 2), the decontamination of the tapes (Step 3), the selection of areas of interest on the tapes, for DNA sampling (Step 4). The method is illustrated by its successful application in four murder cases. In each case, DNA profiles of good quality could be identified, including profiles of persons different from the victim.  相似文献   
863.
Volatile organic compounds (VOCs) are by-products of cadaveric decomposition and are responsible for the odor associated with decomposing remains. The direct link between VOC production and individual postmortem microbes has not been well characterized experimentally. The purpose of this study was to profile VOCs released from three postmortem bacterial isolates (Bacillus subtilis, Ignatzschineria indica, I. ureiclastica) using solid-phase microextraction arrow (SPME Arrow) and gas chromatography–mass spectrometry (GC-MS). Species were inoculated in headspace vials on Standard Nutrient Agar and monitored over 5 days at 24°C. Each species exhibited a different VOC profile that included common decomposition VOCs. VOCs exhibited upward or downward temporal trends over time. Ignatzschineria indica produced a large amount of dimethyldisulfide. Other compounds of interest included alcohols, aldehydes, aromatics, and ketones. This provides foundational data to link decomposition odor with specific postmortem microbes to improve understanding of underlying mechanisms for decomposition VOC production.  相似文献   
864.
An important component of crime scene reconstruction is bloodstain pattern analysis (BPA). Where BPA concerns impact patterns, estimating the area of origin is critical information for scene reconstruction. Traditionally, this is achieved by measuring individual bloodstains and performing trigonometric calculations; however, 3D scanning has been proposed as a viable alternative for overcoming logistical and practical concerns with the manual method. Therefore, this project aimed to establish whether the FARO Focus 3D scanner and FARO Zone 3D software can improve the accuracy of area of origin estimates relative to the manual method. We created a series of eight bloodstain impact patterns and performed paired analysis using the two methods to estimate areas of origin for each pattern. Our data suggested that FARO-derived estimates were generally more accurate than using the manual method. FARO-estimated heights of origin areas were generally closer to the true distance. Both methods underestimated the distance from the wall for most patterns originating 150mm or greater from the wall, but overestimated distances for patterns originating closer to the wall. The degree to which distances were underestimated increased significantly the further the blood source was from the wall and was greater for FARO-derived estimates. The results of this research contribute to the validation of these instruments for operational implementation for BPA and should be considered alongside the practical benefits of 3D scanning relative to manual methods. Further, 3D scanning can provide reliable BPA reconstruction documentation for technical review and court presentation.  相似文献   
865.
In 2007, the Bureau of Justice Statistics reported on 2004 data collected from the Census of Medical Examiner and Coroner Offices (CMEC). The CMEC was one of the first comprehensive reports on the state of the medicolegal death investigation system in the United States and included information on administration, expenditure, workload, specialized death investigations, records and evidence retention, and resources. However, the report did not include responses on questions that were related to toxicology such as specimen retention and type of testing. The purpose of this publication is to provide the community with toxicology laboratory-specific responses from nearly 2000 medical examiner and coroner (MEC) offices. Data obtained from a BJS CMEC public use dataset for any remaining information that was not reported in the 2007 BJS report were evaluated specific to the operation of toxicology laboratories within a MEC office or specific to toxicology testing. The CMEC includes information on average operating budget for MEC offices with internal or external toxicology services, budget for toxicology/microbiology services, respondents’ routine uses of toxicology analysis, toxicology specimen retention time, average turnaround times, use of computerized information management systems, and participation in federal data collections. These historical data begin to address the present state of our nation’s toxicology laboratories within the medicolegal death investigation system and their preparedness for the current drug overdose epidemic.  相似文献   
866.
This study describes the performance of handheld Raman devices for determining whether suspect pharmaceutical tablets declared to contain controlled substances were consistent with authentic (CWA) or not consistent with authentic (NCWA) tablets using a simple, rapid, field-friendly method capable of being used by nonexperts. Twenty-five authentic products and 84 known NCWA tablets were examined using three “parent” devices for a total of 327 analyses. On average, the parent devices yielded a true pass rate of 100%, a true fail rate of 98.4%, a false pass rate of 1.6%, and a false fail rate of 0%. The methods/libraries were then transferred to 13 identical “daughter” devices, which were used to examine 10 suspect finished dosage forms in duplicate (six known NCWA tablets and four authentic tablets) for a total of 260 measurements. On average, the daughter devices had a true pass rate of 100%, a true fail rate of 95.5%, a false pass rate of 4.5%, and a false fail rate of 0.0%. These data demonstrate that the parent–daughter electronic transfer method was successful, which permits the ability to develop methods in the laboratory that can be seamlessly pushed out to field devices. The methods can then be used to (i) prioritize samples for additional testing using other more time-consuming laboratory-based techniques needed to detect and quantify active ingredients and (ii) help support the interdiction of dangerous tablets at ports of entry, thereby preventing them from reaching the supply chain.  相似文献   
867.
Political Behavior - Throughout her 2016 U.S. presidential campaign, Democratic Party nominee Hillary Clinton crafted messages intended to appeal to fathers of daughters and to highlight the...  相似文献   
868.
Jenkins  Jeffery A.  McCarty  Nolan  Stewart  Charles 《Public Choice》2020,185(3-4):245-251
Public Choice - Within political science, a movement focused on increasing the credibility of causal inferences (CIs) has gained considerable traction in recent years. While CI has been...  相似文献   
869.
Boettke  Peter J.  Candela  Rosolino A. 《Public Choice》2020,182(3-4):331-352
Public Choice - This paper reconceptualizes and unbundles the relationship between public predation, state capacity and economic development. By reframing our understanding of state capacity theory...  相似文献   
870.
There is increasing interest in how universities are governed, externally and internally (Austin and Jones 2016). Drawing on a comparative case study of the governance of six major Canadian universities and the literature, this article describes the impact of federal research and innovation policy and programs on universities and reflects on Ottawa's role. We suggest that the federal government participates in the external governance of universities, but in a way that differs significantly from provincial governments. Canadian federalism appears to be generally beneficial for university autonomy and examination of its operation sheds light on factors that enable universities to sustain their autonomy.  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