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   1103篇
  免费   25篇
各国政治   48篇
工人农民   47篇
世界政治   62篇
外交国际关系   25篇
法律   807篇
中国政治   21篇
政治理论   111篇
综合类   7篇
  2023年   4篇
  2022年   5篇
  2021年   9篇
  2020年   18篇
  2019年   27篇
  2018年   26篇
  2017年   25篇
  2016年   34篇
  2015年   20篇
  2014年   19篇
  2013年   77篇
  2012年   32篇
  2011年   30篇
  2010年   23篇
  2009年   20篇
  2008年   29篇
  2007年   16篇
  2006年   15篇
  2005年   29篇
  2004年   42篇
  2003年   37篇
  2002年   26篇
  2001年   101篇
  2000年   67篇
  1999年   73篇
  1998年   35篇
  1997年   4篇
  1996年   3篇
  1995年   8篇
  1994年   4篇
  1993年   7篇
  1992年   22篇
  1991年   18篇
  1990年   39篇
  1989年   26篇
  1988年   29篇
  1987年   23篇
  1986年   14篇
  1985年   13篇
  1984年   8篇
  1983年   8篇
  1982年   11篇
  1981年   8篇
  1980年   4篇
  1979年   11篇
  1978年   7篇
  1972年   2篇
  1971年   4篇
  1970年   3篇
  1968年   2篇
排序方式: 共有1128条查询结果,搜索用时 624 毫秒
101.
The effects of carbon monoxide and cyanide on the hepatic redox state and energy charge were investigated. Rats were used for the experiment under pentobarbital anesthesia. Immediately after laparotomy, a rat was placed in an animal chamber made of a transparent plastic box and exposed to a test gas for 3 min. Every test gas was produced in a gas chamber connected to the animal chamber with a flexible tube. HCN was produced from NaCN and H2SO4. In the CO inhalation experiment, various amounts of CO were introduced into the gas chamber. Immediately after an exposure, about 2 g liver was frozen in situ with a precooled clamp. Oozed blood from the wound surface was sampled. Concentrations of ATP, ADP, AMP, acetoacetate, and beta-hydroxybutyrate in hepatic mitochondria were determined, and the redox state and the energy charge were calculated. For cyanide as well as CO, significant negative correlations were found between the concentration in the blood and the redox state. The same held true for the energy charge. The redox state showed a slight increase at low concentrations of both gases; however, thereafter it began to decrease sharply with increases in concentrations. When concentrations of the toxicant in the blood reached certain levels, a kind of turning point, beyond which the redox state does not decrease any more, was observed. It was about 40% for HbCO and about 2.0 micrograms/ml for cyanide, and the points seemed to be related to the concentrations, beyond which cells are irreversibly damaged. On the other hand, the energy charge did not change at low concentrations. With an increase in toxicant concentrations, the energy charge decreased drastically. The rate of decrease in the energy charge became higher when blood concentrations exceeded certain levels. It was about 40% for HbCO and 2.0 micrograms/ml for cyanide. The presence of low levels of blood cyanide did not affect the relationship between the energy charge and the HbCO concentration.  相似文献   
102.
In July 2005, the Little Rock, Arkansas, school district implemented a new policy to reorganize its management structure in order to create a more efficient bureaucracy. Using Richard Matland’s ambiguity‐conflict model of policy implementation, the authors examine the implementation of this school reorganization policy. Interviews and surveys were conducted with the superintendent and his executive assistants, school principals, teachers, and staff. In line with Matland’s model, the findings suggest that successful implementation is directly related to the policy characteristics of ambiguity and conflict. However, the authors point to the importance of recognizing particular characteristics for different groups of stakeholders within the policy implementation process. Discrepancies among groups of policy actors in the degree of policy ambiguity and policy conflict lead to strikingly different implementation strategies.  相似文献   
103.
104.
105.
106.
The results of grouping tests performed on blood samples collected over a five-year period at the Trinidad and Tobago Forensic Science Centre are presented. The samples were tested using the ABO, PGM, EAP and GLO blood group systems. Phenotypic frequencies and allele frequencies for each system were calculated for the two major ethnic groups of the population, the African and East Indian. Matching probabilities, which can be used in the interpretation of physical evidence in forensic cases, were also calculated.  相似文献   
107.
Economic Change and Restructuring - Recent work in macroeconomics argues that firm market power dramatically increased since the 1980s in the world. The evolution of product markups has important...  相似文献   
108.
109.
110.
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