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   53970篇
  免费   1406篇
  国内免费   24篇
  55400篇
  2020年   392篇
  2019年   503篇
  2018年   4011篇
  2017年   3382篇
  2016年   2902篇
  2015年   742篇
  2014年   739篇
  2013年   3253篇
  2012年   1705篇
  2011年   3525篇
  2010年   3141篇
  2009年   2162篇
  2008年   2639篇
  2007年   3142篇
  2006年   1016篇
  2005年   1130篇
  2004年   1020篇
  2003年   977篇
  2002年   939篇
  2001年   998篇
  2000年   963篇
  1999年   761篇
  1998年   422篇
  1997年   415篇
  1996年   407篇
  1995年   353篇
  1994年   332篇
  1993年   319篇
  1992年   576篇
  1991年   587篇
  1990年   559篇
  1989年   507篇
  1988年   495篇
  1987年   487篇
  1986年   502篇
  1985年   539篇
  1984年   455篇
  1983年   397篇
  1982年   321篇
  1981年   331篇
  1979年   450篇
  1978年   359篇
  1975年   364篇
  1974年   451篇
  1973年   446篇
  1972年   341篇
  1971年   328篇
  1970年   315篇
  1968年   375篇
  1967年   334篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
The present study tested gender as a moderator of the relationship between race-related stress and mental health symptoms among African American adults. Because African American women are exposed to stressors associated with race and gender, we hypothesized that African American women would have higher levels of race-related stress and more severe mental health outcomes related to experiences of race-related stress compared to African American men. Multivariate analyses revealed that African American men had higher stress appraisals for institutional racism than did women. No significant gender differences were found for cultural and individual racism. Moderated regression analyses revealed that increases in stress appraisals for individual racism were associated with increases in anxiety and obsessive-compulsive symptoms for African American women. Race-related stress had no significant effects on mental health symptoms for African American men. The findings suggest that gender is an important factor in determining the impact of race-related stress on mental health.  相似文献   
2.
3.
Rats received Pavlovian conditioning in which food was signalled by a visual stimulus, A+, an auditory stimulus, B+, and a compound composed of different visual and auditory stimuli, CD+. Test trials were then given with the compound AB. Experiments 1 and 2A revealed stronger responding during AB than during CD. In Experiment 2B, there was no evidence of a summation of responding during AB when A+ B+ training was conducted in the absence of CD+ trials. A further failure to observe abnormally strong responding during ABwas found in Experiment 3 for which the training trials with A+ B+ CD+ were accompanied by trials in which C and D were separately paired with food. The results are explained in terms of a configural theory of conditioning, which assumes that responding during a compound is determined by generalization from its components, as well as from other compounds to which it is similar.  相似文献   
4.
Most arguments against active euthanasia, as do most arguments in applied ethics generally, take place within the framework of what can broadly be referred to as a modern, as opposed to an ancient, approach to moral theory. In this paper, I argue that this fact works to the disadvantage of opponents of active euthanasia, and that if there is a successful argument against active euthanasia, it will be of the latter sort. In Part I, I attempt to clarify thedistinction between modern and ancient approaches with which I am concerned. In Part II, I attempt to show that any argument against active euthanasia that is of the first sort is bound to fail. In Part III, I propose an argument against active euthanasia of the second sort that I believe has a better chance for success. In Part IV, I consider some objections that can be raised against this argument and attempt to show how they can be overcome.  相似文献   
5.
6.
7.
8.
9.
10.
Range of electric vehicles (EVs) has long been considered a major barrier in acceptance of electric mobility. We examined the nature of how range is experienced in an EV and whether variables from other adaptation contexts, notably stress, have explanatory power for inter‐individual differences in what we term comfortable range. Forty EVs were leased to a sample of users for a 6‐month field study. Qualitative and quantitative analyses of range experiences were performed, including regression analyses to examine the role of stress‐buffering personality traits and coping skills in comfortable range. Users appraised range as a resource to which they could successfully adapt and that satisfied most of their daily mobility needs. However, indicators were found that suggested suboptimal range utilisation. Stress‐buffering personality traits (control beliefs, ambiguity tolerance) and coping skills (subjective range competence, daily range practice) were found to play a substantial role in comfortable range. Hence, it may be possible to overcome perceived range barriers with the assistance of psychological interventions such as information, training, and interface design. Providing drivers with a reliable usable range may be more important than enhancing maximal range in an electric mobility system.  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