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   20400篇
  免费   560篇
各国政治   822篇
工人农民   768篇
世界政治   1638篇
外交国际关系   693篇
法律   12530篇
中国共产党   2篇
中国政治   108篇
政治理论   4212篇
综合类   187篇
  2020年   247篇
  2019年   296篇
  2018年   387篇
  2017年   472篇
  2016年   478篇
  2015年   343篇
  2014年   399篇
  2013年   1906篇
  2012年   481篇
  2011年   524篇
  2010年   414篇
  2009年   462篇
  2008年   535篇
  2007年   535篇
  2006年   529篇
  2005年   478篇
  2004年   489篇
  2003年   506篇
  2002年   455篇
  2001年   825篇
  2000年   723篇
  1999年   592篇
  1998年   319篇
  1997年   283篇
  1996年   237篇
  1995年   251篇
  1994年   282篇
  1993年   271篇
  1992年   409篇
  1991年   437篇
  1990年   401篇
  1989年   397篇
  1988年   386篇
  1987年   407篇
  1986年   420篇
  1985年   422篇
  1984年   355篇
  1983年   385篇
  1982年   282篇
  1981年   269篇
  1980年   199篇
  1979年   274篇
  1978年   197篇
  1977年   169篇
  1976年   146篇
  1975年   150篇
  1974年   179篇
  1973年   140篇
  1972年   136篇
  1971年   122篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
951.
In a report released on 20 November 2002, entitled Action on HIV/AIDS in Prisons: Too Little, Too Late--A Report Card, the Canadian HIV/AIDS Legal Network concluded that despite repeated studies and nearly ten years of recommendations for urgent and pragmatic action, the response of Canadian governments to HIV/AIDS, HCV, and injection drug use in prisons remains inadequate. Only a few weeks later, the House of Commons Special Committee on Non-Medical Use of Drugs released its report, which contained a number of recommendations to the Correctional Service of Canada. Although the Committee avoided talking about needle exchange programs in prisons, it did recommend them! Meanwhile, in Ireland, not even condoms or bleach are provided.  相似文献   
952.
Since the concept of "brain death" was introduced in medical terminology, enough evidence has come to light to show that the concept is based on an unclear and incoherent theory. The "brain death" concept suffers by internal inconsistencies in both the tests-criterion and the criterion-definition relationships. It is also evident that there are residual vegetative functions in "brain dead" patients. Since the content of consciousness is inaccessible in these patients who are in a profound coma, the diagnosis of "brain death" is based on an unproved hypothesis. A critical evaluation of the role and the limitations of the confirmatory tests in the diagnosis of "brain death" is attempted. Finally it is pointed out that a holistic approach to the problem of "brain death" in humans should necessarily include the inspection of the content of consciousness.  相似文献   
953.
954.
Statistical models are often extended to explore the aggregateimpact of policy reforms. After discussing these techniquesand the incorporation of prediction uncertainty, this articleexamines the effects of registration reform in an analytic frameworkthat explicitly considers the two stages that defined electoralparticipation throughout the 20th century in the United States—registrationand then voting. Using selection bias techniques, the effectsof counterfactual registration reform conditions are exploredon the aggregate level of participation and the nature of representationin the electoral process. These offer a richer baseline of theimpact of policy changes than previous work by directly exploringthe expected level of dropoff in going to the polls by new registrants.Results indicate that the dropoff between registration and votingwould be expected to increase as more individuals become registered.In addition, while turnout due to reforms among projected "newregistrants" shows potentially larger biases than those amongexisting registrants, because of the different bases of registrationthe changes would still lead to a modest reduction in the disparitybetween actual group sizes and their role in elections.  相似文献   
955.
Nash JM 《Time》2002,159(18):46-56
  相似文献   
956.
957.
Comparing skeletal structures between antemortem and postmortem chest radiographs is widely used by forensic specialists from many disciplines to positively identify unknown decedents. However, validity assessments of this method have been fairly limited. This study had three objectives: 1) to quantify the reliability of ante- and postmortem chest radiograph comparison for decedent identification; 2) to identify useful radiologic features supporting decedent identification; and 3) to recognize sources of error in decedent identification related to use of comparative radiographs. A forensic pathologist, a forensic anthropologist, and two radiologists participated in the study. Our results showed that chest radiograph comparisons proved reliable, if basic decedent information was provided, and antemortem and postmortem radiographs were adequately positioned and exposed. A "morphological approach" using normal anatomical structures for comparison may provide the most efficient method for accurate identification.  相似文献   
958.
The projection of the cornea from the bony orbit has been determined, in facial approximation, by centrally locating the eyeball in the orbit and positioning the cornea so that its most anterior point falls in line with a tangent dropped from the mid-superior to the mid-inferior orbital rim. However, there appears to be no scientific evidence to justify this guideline; yet, there have been numerous studies that measure globe projection in living subjects, from the lateral orbit using an exophthalmometer. The aim of this study was to determine if the traditional facial approximation guideline is consistent with the exophthalmometry literature. MRI research shows that corneal projection is underestimated using the traditional facial approximation guideline. An underestimation is also strongly supported by statistical comparisons of globe projection measures taken using more traditional instruments (e.g., Hertel's exophthalmometer) to skull morphology (p < 0.006). It is suggested that the traditional facial approximation guideline not be used in future facial approximations since it appears to under-predict anterior globe projection by 4 mm on average. It is also suggested that average exophthalmometer values be used until more accurate and precise ways of determining globe projection have been determined.  相似文献   
959.
Validation of a 16-locus fluorescent multiplex system   总被引:24,自引:0,他引:24  
STR multiplexes have been indispensable for the efficient genotyping of forensic samples. The PowerPlex 16 System contains the coreCODIS loci, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D21S11, CSF1PO, FGA, THOI, TPOX, vWA, the sex determinant locus, amelogenin, and two pentanucleotide STR loci, Penta D and Penta E. This multiplex satisfies the locus requirements for most national databases and is the most efficient currently available system due to its single PCR amplification. To provide the groundwork for judicial acceptance, including the publication of primer sequences, and to evaluate laboratory-to-laboratory variation, a developmental validation for casework on this commercially available system was performed in 24 laboratories and produced the following conclusions. Amplification was reliable on a variety of thermal cyclers and product could be analyzed on either an ABI PRISM 310 Genetic Analyzer or an ABI PRISM 377 DNA Sequencer. Genotyping using single source samples was consistent between 0.25 and 2 ng of input DNA template with a few laboratories obtaining complete genotypes at 0.0625 ng. However, heterozygote allele imbalance (<60% peak height balance) caused by stochastic effects was observed at a rate of 13% with 0.125 ng DNA and 22% at 0.0625 ng DNA. Mixture analyses were done using a total of 1 ng of DNA template. Most alleles were detected in mixtures of 4 to 1 and some minor alleles were detected in mixtures of 19 to 1. Optimum amplification cycle number was dependent on the sensitivity of the detection instrument used and could also be adjusted to accommodate larger amounts of DNA on solid supports such as FTA paper. Reaction conditions including volume, annealing temperature, and concentrations of primer, AmpliTaq Gold, and magnesium were shown to be optimal yet robust enough to withstand moderate variations without affecting genotype analysis. Environmental, matrix and standard source analyses revealed an ability to obtain complete genotypes in all sample types except those exposed to 80 degrees C for 12-48 days. Finally, comparison of genotype results from the PowerPlex 16 System with other commercially available systems on non-probative reference and forensic samples showed consistent results.  相似文献   
960.
Assessment of the role of air bag deployment in injury causation in a crash of any severity requires analysis of occupant, vehicle, and impact data. The potential injurious role of an air bag is independent of crash severity and is more obvious in minor collisions, particularly those involving "out-of-position" occupants. Factors such as occupant height and other constitutional and medical factors, intoxication, age, type, and proper use of other restraint systems, pre-impact braking and multiple impacts can contribute to an occupant being "out-of-position." Two injury mechanisms are described in out-of-position occupants: "punch-out" when the individual covers the air bag module before deployment and "membrane-force" when the occupant contacts a partly deployed air bag. Each mechanism is associated with injury patterns. In adults, "punch-out" can cause thoraco-abdominal trauma and "membrane-force" loading can lead to craniocervical injury. This can also occur in short-statured occupants including children subjected to both types of loading. In more severe collisions, other factors, e.g., intrusion, steering column and seatbelt loading and other occupant compartment contacts, can contribute to trauma.  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