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   20066篇
  免费   908篇
  国内免费   11篇
  2021年   191篇
  2020年   301篇
  2019年   310篇
  2018年   464篇
  2017年   437篇
  2016年   454篇
  2015年   350篇
  2014年   408篇
  2013年   1636篇
  2012年   794篇
  2011年   705篇
  2010年   488篇
  2009年   433篇
  2008年   655篇
  2007年   637篇
  2006年   549篇
  2005年   496篇
  2004年   421篇
  2003年   368篇
  2002年   394篇
  2001年   746篇
  2000年   747篇
  1999年   503篇
  1998年   196篇
  1997年   194篇
  1996年   182篇
  1995年   160篇
  1992年   386篇
  1991年   363篇
  1990年   391篇
  1989年   336篇
  1988年   309篇
  1987年   317篇
  1986年   284篇
  1985年   282篇
  1984年   260篇
  1983年   223篇
  1982年   165篇
  1979年   249篇
  1978年   183篇
  1975年   212篇
  1974年   253篇
  1973年   248篇
  1972年   202篇
  1971年   196篇
  1970年   168篇
  1969年   188篇
  1968年   227篇
  1967年   202篇
  1966年   166篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The cynomolgus macaque provides a suitable primate model for studying how psychosocial factors contribute to coronary artery atherogenesis. Important interactions with diet, sex, and behaviorally elicited cardiovascular reactivity are described.  相似文献   
72.
A cost-benefit analysis of demand for food.   总被引:20,自引:17,他引:3       下载免费PDF全文
Laboratory studies of consumer demand theory require assumptions regarding the definition of price in the absence of a medium of exchange (money). In this study we test the proposition that the fundamental dimension of price is a cost-benefit ratio expressed as the effort expended per unit of food value consumed. Using rats as subjects, we tested the generality of this "unit price" concept by varying four dimensions of price: fixed-ratio schedule, number of food pellets per fixed-ratio completion, probability of reinforcement, and response lever weight or effort. Two levels of the last three factors were combined in a 2 x 2 x 2 design giving eight groups. Each group was studied under a series of six FR schedules. Using the nominal values of all factors to determine unit price, we found that grams of food consumed plotted as a function of unit price followed a single demand curve. Similarly, total work output (responses x effort) conformed to a single function when plotted in terms of unit price. These observations provided a template for interpreting the effects of biological factors, such as brain lesions or drugs, that might alter the cost-benefit ratio.  相似文献   
73.
Two experiments investigated the effects of successive reinforcement contexts on choice. In the first, concurrent variable-interval schedules of primary reinforcement operated during the initial links of concurrent chains. The rate of this reinforcement arranged by the concurrent schedules was decreased across conditions: When it was higher than the terminal-link rate, preference for the higher frequency initial-link schedule increased relative to baseline. (During baseline, a standard concurrent-schedule procedure was in effect). When the initial-link reinforcement rate was lower than the terminal-link rate, preference converged toward indifference. In the second experiment, a chain schedule was available on a third key while a concurrent schedule was in effect on the side keys. When the terminal link of the chain schedule was produced, the side keys became inoperative. Availability of the chain schedule did not affect choice between the concurrent schedules. These results show that only when successive reinforcement contexts are produced by choice responding do those successive contexts affect choice in concurrent schedules.  相似文献   
74.
75.
This report examines two methodologic concerns pertaining to use of the cloze procedure in studying the predictability of schizophrenic speech, scoring criteria and raters' education (at or below college level). We find that two strategies for scoring the predictions of raters, one requiring the exact word, the other permitting a reasonable synonym, do not appear to differ in distinguishing groups of patients. The accuracy of raters' guessing is, however, correlated with raters' education: the more educated the rater, the more accurate the guessing. Thought-disordered schizophrenic speech is significantly less predictable than that of nonthought-disordered schizophrenics and normal controls when scored by less educated raters. These differences diminish when more highly educated raters are used. We conclude that raters' education can influence the sensitivity of cloze analysis.  相似文献   
76.
Individuals with stronger sex-role identities may be expected to show greater conformity to sex-typed behaviors. Proceeding from this assumption, the sex-role status and sex of students using different styles of carrying books were compared. This study also examined whether over-all hand preference or age were related to carrying styles or sex-role status. Subjects completed a questionnaire comprised of the 24-item Personal Attributes Questionnaire of Spence and Helmreich, a 6-item scale of hand preference and a self-rating of sex-role identity. Afterwards, each subject's carrying style was covertly observed and recorded. Most subjects carried their materials in a sex-typical way or in book bags (for which no sex-typed carrying styles were discovered). As in previous studies, men in this study scored higher than women on masculinity and androgyny and lower on femininity. Hand preference was not related to sex-role status. Carrying style was not significantly correlated with any of the predictor variables for men, perhaps because almost no variance in carrying style was observed among them. Women who used masculine carrying styles tended to be older, have greater instrumentality, and a more masculine identity.  相似文献   
77.
Of 1240 first-time consultations in the neuropsychiatric clinic of the Gondar College of Medical Sciences in an eleven-month period during 1985 and 1986, 152 patients came seeking relief from seizures. This paper deals with the origins and background of diagnostic, differential diagnostic, and therapeutic problems, and with problems of social rehabilitation. While in such a tradition-bound society certain hypotheses continue to have an unfavorable effect, there are unmistakable signs of positive change against a background of rapid social change. Conclusions are drawn for the better management of epileptic patients in developing countries.  相似文献   
78.
W Lüders 《Psyche》1988,42(3):216-220
  相似文献   
79.
80.
Stress, locus of control, and achievement of high school seniors   总被引:1,自引:0,他引:1  
  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