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   2529篇
  免费   58篇
各国政治   124篇
工人农民   278篇
世界政治   150篇
外交国际关系   126篇
法律   1438篇
中国政治   25篇
政治理论   434篇
综合类   12篇
  2023年   7篇
  2022年   4篇
  2021年   6篇
  2020年   26篇
  2019年   33篇
  2018年   55篇
  2017年   47篇
  2016年   45篇
  2015年   97篇
  2014年   84篇
  2013年   417篇
  2012年   101篇
  2011年   92篇
  2010年   109篇
  2009年   117篇
  2008年   102篇
  2007年   115篇
  2006年   106篇
  2005年   117篇
  2004年   106篇
  2003年   50篇
  2002年   71篇
  2001年   105篇
  2000年   34篇
  1999年   20篇
  1998年   17篇
  1997年   34篇
  1996年   38篇
  1995年   24篇
  1994年   31篇
  1993年   24篇
  1992年   37篇
  1991年   26篇
  1990年   20篇
  1989年   26篇
  1988年   19篇
  1987年   18篇
  1986年   28篇
  1985年   21篇
  1984年   18篇
  1983年   14篇
  1982年   24篇
  1981年   17篇
  1980年   15篇
  1979年   12篇
  1978年   15篇
  1977年   14篇
  1976年   5篇
  1975年   7篇
  1974年   6篇
排序方式: 共有2587条查询结果,搜索用时 31 毫秒
81.
82.
The following paper was discovered by Laurence Evans, Professor of History at the State University of New York at Binghamton, during the course of research in the files of the Department of State (to which Department the paper had been made available in 1918 for use as background information by the American Delegation at the Peace Conference), and Professor Evans has kindly communicated it to the Society. Its contents are not included in the book on Mecca which Snouk published in German, and it is not among the scattered articles in Verspreide Geschriften (1923–27). That collection does, however, include another essay about Ahmad Dahlan, in Dutch, entitled “Een rector der Mekkaansche universiteit”, originally contributed to a learned journal and reprinted in vol. 111, pp. 65–122. [We are printing this paper in good faith believing it to be previously unpublished. Ed.]  相似文献   
83.
84.
85.
86.
Journal of Youth and Adolescence - Adolescents are spending considerable time on social media, yet it is unclear whether motivations for social media use drive different forms of social media...  相似文献   
87.
88.
Journal of Youth and Adolescence - Parent–adolescent conflict can be intense, yet parents and adolescents do not always agree on the intensity of conflict. Conflict intensity tends to change...  相似文献   
89.
Social Justice Research - A cross-national study with university students from Germany (n?=?1135) and Turkey (n?=?634) tested whether personal belief in a just world (PBJW)...  相似文献   
90.
Ammonium nitrate fuel oil is an explosive mixture found in most antipersonnel landmines (APL) buried throughout the Colombian territory. During more than 50 years of internal conflict, the Colombian government has found that trained dogs are the most effective method to detect APL. However, the olfactive signature in ANFO is unknown and also if there are differences in detection related to the explosive manufacturing origin. Therefore, this work begins with the analytical validation of the method used to determine ammonia, in its derivatized form as carbamate, released by home-made ANFO using HS-SPME-GC-FID. Once validated, the method was used to identify ammonia and other organic volatile compounds present in ANFO, under laboratory and simulated field conditions. The validation process includes the evaluation of the optimum conditions for the derivation and extraction of butylcarbamate, the determination of the working ranges with linear response in FID, the limits of detection and quantification, the sensitivity, and the precision. The results of the validation established linearity and sensitivity in a concentration between 20 and 120 mg/L, as well as low limits of detection and quantification of 6.4 and 21.4 mg/L, respectively. Also, an intermediate precision of 11% for butylcarbamate with a repeatability of 8%. The validated method showed in real samples of home-made ANFO besides ammonia, the presence of low molecular methylamines, and also exhibited differences in volatile compositions according to the origin. The objective of this work is to offer a reliable analytical methodology for the extraction and analysis of volatile compounds from ANFO.  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