全文获取类型
收费全文 | 7214篇 |
免费 | 162篇 |
专业分类
各国政治 | 430篇 |
工人农民 | 310篇 |
世界政治 | 435篇 |
外交国际关系 | 267篇 |
法律 | 4451篇 |
中国政治 | 40篇 |
政治理论 | 1394篇 |
综合类 | 49篇 |
出版年
2020年 | 72篇 |
2019年 | 87篇 |
2018年 | 116篇 |
2017年 | 140篇 |
2016年 | 148篇 |
2015年 | 105篇 |
2014年 | 137篇 |
2013年 | 772篇 |
2012年 | 145篇 |
2011年 | 154篇 |
2010年 | 149篇 |
2009年 | 150篇 |
2008年 | 177篇 |
2007年 | 190篇 |
2006年 | 190篇 |
2005年 | 153篇 |
2004年 | 144篇 |
2003年 | 166篇 |
2002年 | 132篇 |
2001年 | 275篇 |
2000年 | 234篇 |
1999年 | 223篇 |
1998年 | 95篇 |
1997年 | 80篇 |
1996年 | 73篇 |
1995年 | 65篇 |
1994年 | 75篇 |
1993年 | 69篇 |
1992年 | 122篇 |
1991年 | 161篇 |
1990年 | 158篇 |
1989年 | 144篇 |
1988年 | 150篇 |
1987年 | 167篇 |
1986年 | 160篇 |
1985年 | 148篇 |
1984年 | 133篇 |
1983年 | 121篇 |
1982年 | 86篇 |
1981年 | 96篇 |
1980年 | 72篇 |
1979年 | 128篇 |
1978年 | 89篇 |
1977年 | 72篇 |
1976年 | 56篇 |
1975年 | 81篇 |
1974年 | 86篇 |
1973年 | 83篇 |
1972年 | 56篇 |
1971年 | 57篇 |
排序方式: 共有7376条查询结果,搜索用时 0 毫秒
901.
Liver tends to concentrate drugs in quantities generally higher than those found in blood or other body compartments. This fact as well as the general availability of liver in postmortem cases makes it an important specimen for comprehensive toxicologic investigation. A scheme for the analysis of liver for drugs with tissue hydrolysis, XAD-2 resin extraction, and TLC has been developed and the parameters affecting recovery have been studied. The hydrolysis of liver specimens at various pH conditions resulted in an improved recovery for morphine by using pH 2 (2N hydrochloric acid). Recoveries of barbiturates, codeine, and meperidine were essentially the same at pH 2 and pH 3. A considerable loss (22 to 55%) was observed for four drugs (pentobarbital, morphine, codeine, and meperidine) as a result of drug binding to the tissue pellets during the process of centrifuging the liver homogenates. This method is recommended as a comprehensive screening procedure for drugs in liver tissue. For quantitative purposes, however, it is necessary to determine a correction factor for all the losses occurring at the various steps of the procedure. This procedure compared favorably with other procedures for liver analysis reported in literature. 相似文献
902.
903.
904.
905.
Extravasation of plasma proteins in brain trauma 总被引:2,自引:0,他引:2
The cellular distribution of extravasated plasma proteins in cortical contusions was studied with an immunoperoxidase method using polyclonal antibodies against human plasma albumin, alpha 1-acid glycoprotein, alpha 2-macroglobulin, alpha 1-antitrypsin, transferrin, hemopexin, haptoglobin, fibrinogen, fibronectin and immunoglobulin G. The material consisted of 24 human autopsy brains with a primary diagnosis of cerebral contusion due to blunt trauma. The time interval between injury and death ranged between minutes and 7 years. Immediately after the trauma, a complete breakdown of the blood-brain barrier (BBB) occurred with hemorrhage and extravasation of all types of plasma proteins. This was followed by spreading of edema fluid within the extracellular space in and around the wound. Uptake of extravasated protein by glial cells began on the 3rd day followed by proliferation of reactive astrocytes whose ample cytoplasm appeared to serve as a reservior for the extravasated plasma proteins. Within the reactive astrocytes, plasma proteins and S-100 protein had a similar and diffuse distribution in the immunostained sections. The plasma proteins once incorporated into the glial cells remained unchanged for several years with little sign of degradation. It is suggested that the extravasated plasma proteins subsequent to uptake and processing by the glial cells, may serve some important physiological function in wound healing. 相似文献
906.
907.
We have shown first, that if the electoral college was abolished the theoretically measured power of voters would increase and second, that in presidential elections the measure of voting power used does in fact have a highly significant impact on the decision as to whether or not to vote. Thus, the analysis predicts that the abolition of the electoral college would have a significant impact on voter participation. From a policy viewpoint, if we view participation in elections as desirable, this could be used as an argument in favor of direct election of the president. From a scientific viewpoint, we are able to make a strong and unambiguous prediction about the results of a (possible) future event from theoretical considerations. If the electoral college should be abolished, it will be possible to test our predictions. In addition, we have provided a further test of the rational behavior view of electoral participation and have shown that this model applies to presidential elections. Finally, we have shown that the theoretical measure of voting power does predict actual behavior. 相似文献
908.
909.
Loren H. Roth 《Law and human behavior》1995,19(1):15-23
This article describes the important ways in which Saleem Shah contributed to the improvement of delivery of forensic mental health services in state mental health systems throughout the nation. In addition, it describes his impact on the development of forensic mental health law, policy, and services internationally, especially in China and the former Soviet Union. 相似文献
910.
Peter H. Gleick 《Policy Sciences》1988,21(1):23-39
International water resources have been a source of contention in many parts of the world over the last few decades and such conflicts may grow in frequency and severity as future climatic changes alter the quantity or quality of limited water resources. Indeed, some future climatic changes appear inevitable due to growing atmospheric concentrations of carbon dioxide and other trace gases. Unless mechanisms for incorporating climatic changes into water agreements can be worked out, these changes may provoke further frictions and conflicts. One region with a history of political conflict over shared water resources is the Colorado River Basin in the United States and Mexico. While past disagreements over water have mostly been resolved, future climatic changes that adversely affect the existing hydrologic regime of the basin cannot be discounted. This paper examines the possibility that future long-term climatic changes may exacerbate shortages in the Colorado River. Political conflicts and tensions that arise from reductions in water supply in both the United States and Mexico are evaluated and discussed, together with recommendations for incorporating the issue of climatic change into existing international treaties and agreements. 相似文献