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   22225篇
  免费   1245篇
各国政治   896篇
工人农民   1021篇
世界政治   1566篇
外交国际关系   729篇
法律   15025篇
中国共产党   2篇
中国政治   143篇
政治理论   3984篇
综合类   104篇
  2021年   124篇
  2020年   480篇
  2019年   534篇
  2018年   683篇
  2017年   679篇
  2016年   755篇
  2015年   557篇
  2014年   628篇
  2013年   2309篇
  2012年   593篇
  2011年   641篇
  2010年   637篇
  2009年   678篇
  2008年   650篇
  2007年   635篇
  2006年   633篇
  2005年   542篇
  2004年   567篇
  2003年   460篇
  2002年   490篇
  2001年   905篇
  2000年   801篇
  1999年   622篇
  1998年   309篇
  1997年   243篇
  1996年   234篇
  1995年   239篇
  1994年   215篇
  1993年   210篇
  1992年   399篇
  1991年   422篇
  1990年   394篇
  1989年   382篇
  1988年   392篇
  1987年   367篇
  1986年   397篇
  1985年   396篇
  1984年   325篇
  1983年   302篇
  1982年   227篇
  1981年   222篇
  1980年   174篇
  1979年   281篇
  1978年   156篇
  1977年   116篇
  1975年   128篇
  1974年   166篇
  1973年   127篇
  1972年   110篇
  1971年   97篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
931.
This article describes a nationwide empirical study that will be undertaken during the next three years into the newly emerging phenomenon of genetic discrimination. In particular, the study aims to investigate the nature and extent of genetic discrimination in Australia across three key perspectives: consumers, third parties and the legal system. Further, the study aims to examine the social and legal implications of genetic discrimination, with a view to making recommendations for use in the Australian legal and policy context. It is anticipated that the data produced from this multifaceted investigation will assist in identifying areas where legal or other reforms are required. It will contribute significant baseline data for facilitating ongoing assessment of the nature and extent of the problem, as well as for longitudinal evaluation of the impact and effectiveness of any reforms which may be introduced in the future to address the issue.  相似文献   
932.
Increasingly women are seeking to establish pregnancies using sperm retrieved from their dead or dying partners. This raises a number of issues of a broad nature, but is also of significance in terms of the relationship between regulatory mechanisms and private choices. This article reviews this relationship with specific reference to the United Kingdom position, but also taking account of case law and regulation in Australia, particularly in the State of Victoria.  相似文献   
933.
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   
934.
This article offers a philosophical foundation for the Uniform Determination of Death Act as it first examines death per se, and then examines brain death and the non-heart beating donor criteria for determining death. The author suggests that many of the debates over death can be bypassed by changing the terms of the debate: what matters is not whether death is a process or an event, but death as a state. Understanding death as a state allows us to determine death in a functional manner that is compatible with the needs of law and medicine. The second part examines objections that arise from ignoring or rejecting the distinction between killing and letting die and the principle of double effect. By clarifying the lines between life and death, on the one hand, and between intentionally killing and unintentionally hastening death, on the other, the author hopes to restore a sense that the proposals to drop the dead donor rule are radical recommendations to cross lines we have never crossed before.  相似文献   
935.
Horowitz JM 《Time》2002,160(23):101
  相似文献   
936.
937.
The concentrations of antimony, copper, tin, arsenic, silver, bismuth, and cadmium in lead alloys produced by two smelters and one ammunition manufacturer were determined using inductively coupled plasma-atomic emission spectrometry. These element concentrations were used to measure the variations in composition of lead products that result from various processes involved in the manufacture of lead projectiles. In general, when a pot containing molten lead is used to cast a number of objects, these objects are similar, although not necessarily analytically indistinguishable in their elemental compositions. In each subsequent step in the processing of lead at the smelter and at the ammunition manufacturer, the size of an individual homogeneous melt of lead decreases as more distinct compositions are formed as a result of remelting and mixing of sources, including lead scrap. The ammunition manufacturer in this study produced at least 10 compositionally distinguishable groups of bullet wire in a 19.7-h period. The largest group could potentially be used to produce a maximum of 1.3 million compositionally indistinguishable 40 grain bullets.  相似文献   
938.
Laser desorption mass spectrometry (LDMS) may be used for the detection and identification of dyes found in inks. Naturally-aged and artificially-aged blue and black ballpoint pen inks containing the cationic dye methyl violet were analyzed on paper. The average molecular weight of the dye sample was calculated from LD mass spectral data and plotted versus time. The resulting aging curves demonstrate that, as dye degradation increases, the average molecular weight of the dye decreases. Typical variables involved in ink aging, such as the type of paper and ink formulation, were investigated. Results show that these variables influence the rate of dye degradation. Furthermore, UV accelerated aging has been developed and tested as an alternative to thermal approaches.  相似文献   
939.
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   
940.
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   
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