首页 | 官方网站   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   18753篇
  免费   295篇
  国内免费   2篇
社会科学   19050篇
  2023年   95篇
  2022年   88篇
  2021年   108篇
  2020年   280篇
  2019年   375篇
  2018年   494篇
  2017年   672篇
  2016年   458篇
  2015年   354篇
  2014年   476篇
  2013年   3461篇
  2012年   625篇
  2011年   524篇
  2010年   435篇
  2009年   373篇
  2008年   431篇
  2007年   412篇
  2006年   431篇
  2005年   400篇
  2004年   343篇
  2003年   335篇
  2002年   367篇
  2001年   493篇
  2000年   460篇
  1999年   427篇
  1998年   323篇
  1997年   282篇
  1996年   304篇
  1995年   276篇
  1994年   323篇
  1993年   254篇
  1992年   310篇
  1991年   327篇
  1990年   295篇
  1989年   267篇
  1988年   268篇
  1987年   254篇
  1986年   220篇
  1985年   250篇
  1984年   258篇
  1983年   218篇
  1982年   184篇
  1981年   140篇
  1980年   149篇
  1979年   173篇
  1978年   139篇
  1977年   119篇
  1976年   93篇
  1975年   104篇
  1974年   104篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
EXAMINING THE WAGE DIFFERENTIAL FOR MARRIED AND COHABITING MEN   总被引:3,自引:0,他引:3  
Wage analyses indicate that married and cohabiting men earn more than do single, noncohabiting men. This article examines the nature of these wage differentials using data from the National Survey of Families and Households. Results indicate that the marital and cohabitation differentials are quite distinct. The higher wage observed for cohabiting men is driven primarily by selection and is eliminated by first differencing, but the higher wage observed for married men (and perhaps long-term cohabiters) arises largely because of differential wage growth. Wages appear to rise more rapidly following marriage.  相似文献   
5.
TOOLS OR TOYS? THE IMPACT OF HIGH TECHNOLOGY ON SCHOLARLY PRODUCTIVITY   总被引:1,自引:0,他引:1  
We examine the impact of communication technology on scholarly productivity by considering patterns of coauthored economics articles. Using articles in three major economics journals from 1970–79 and 1992–96, we find (1) sharp growth from distant coauthorships (authors not in the same metropolitan area prior to publication), as the theory predicts, and, contrary to theory, (2) lower productivity of distant than close-coauthored works and no decline in their relative disadvantage. These findings are reconciled by noting that high technology has aspects of a consumer good. The relative productivity of solo-authored articles has decreased, perhaps explaining the secular increase in coauthorship.  相似文献   
6.
Can universities be agents of progressive social change? How would we know if a university was acting as an agent of social change? Drawing on four case studies, I raise a number of questions to problematize our understanding of the university as an agent of social change. I outline a number of contributing factors that appear to explain successful cases. I conclude by arguing the relevancy of these cases for larger, and more traditional, sociological projects.  相似文献   
7.
In a longitudinal, community-based study, adolescent protective factors for those at risk for depression were identified that were associated with resilient outcomes in young adulthood. For those with childhood risk factors for major depression, significant protective factors included family cohesion, positive self appraisals, and good interpersonal relations. Findings may help inform the development of prevention and treatment programs for adolescents vulnerable to depression. Implications for future research and clinical practice are discussed.  相似文献   
8.
As a very small state, Luxembourg would not appear to qualify as an influential foreign policy actor either in Europe or the world. Yet the country's international influence has long belied its reputation as a small state. This article reviews the literature on small-state foreign policy and finds that it offers numerous contradictory conclusions. As a case study it then addresses Luxembourg in the 1990s, with particular attention to two themes: its active participation in the European Union (EU) and its policies directed at maintaining economic prosperity. The paper goes on to explain Luxembourgish foreign policy behaviour through three levels of analysis and assesses to what extent smallness is a benefit or a hindrance to Luxembourg's success in meeting its international goals.  相似文献   
9.
A NOTE ON EVANESCENT PROCESSES   总被引:1,自引:0,他引:1  
This note examines the connection between μ-invariant measures for the transition function of a continuous-time Markov chain and those of its q-matrix, Q. The major result establishes a necessary and aufficient condition for a convergent μ-invariant measure for Q to be μ-inhant for the minimal transition function, P, under the assumption that P is honest. This corrects Theorem 6 of Vere-Jones (1969) and the first part of Corollary 1 of Pollett (1986), both of which assert that the above conclusion holds in the absence of this condition. The error was pointed out by E.A. van Doom (1991) and the counterexample which be presented provides the basis for the present arguments. In determining where the error occurred in the original proof, we are able to identify a simple sufficient condition for μ-invariance.  相似文献   
10.
This paper describes the design optimization of a robot sensor used for locating 3-D objects employing the Taguchi method in a computer simulation scenario. The location information from the sensor is to be utilized to control the movements of an industrial robot in a 'pick-and-place' or assembly operation. The Taguchi method, which is based on the Analysis-of-Variance (ANOVA) approach, is utilized to improve the performance of the sensor over a wider operating range. A review of the Taguchi method is presented along with step-by-step implementation details to identify and optimize the design parameters of the sensor. The method allows us to gauge the impact of various interactions present in the sensor system exclusively and permits us to single out those factors that have a dominant influence on the overall performance of the sensor. The investigation suggests that the Taguchi method is a more structured and efficient approach for achieving a robust design compared with the classical full factorial design approach.  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-23

京公网安备 11010802026262号