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   15420篇
  免费   356篇
  国内免费   1篇
管理学   1976篇
民族学   114篇
人才学   4篇
人口学   1415篇
丛书文集   85篇
理论方法论   1360篇
综合类   123篇
社会学   7460篇
统计学   3240篇
  2023年   73篇
  2021年   85篇
  2020年   227篇
  2019年   299篇
  2018年   397篇
  2017年   534篇
  2016年   370篇
  2015年   314篇
  2014年   362篇
  2013年   2891篇
  2012年   507篇
  2011年   415篇
  2010年   371篇
  2009年   285篇
  2008年   360篇
  2007年   361篇
  2006年   342篇
  2005年   333篇
  2004年   281篇
  2003年   294篇
  2002年   326篇
  2001年   401篇
  2000年   365篇
  1999年   328篇
  1998年   258篇
  1997年   224篇
  1996年   261篇
  1995年   244篇
  1994年   248篇
  1993年   214篇
  1992年   242篇
  1991年   262篇
  1990年   238篇
  1989年   206篇
  1988年   250篇
  1987年   233篇
  1986年   166篇
  1985年   214篇
  1984年   225篇
  1983年   213篇
  1982年   153篇
  1981年   132篇
  1980年   124篇
  1979年   151篇
  1978年   129篇
  1977年   111篇
  1976年   90篇
  1975年   91篇
  1974年   84篇
  1973年   77篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
821.
Recursion relations suitable for rapid computation are derived for the probabilities of the compound Poisson distribution when the compounder is the inverse-Gaussian distribution. Series representation of the probabilities are given. Asymptotic results as well as approximations for probabilities, compared with the exact values, are investigated.  相似文献   
822.
We examine differences in the value of statistical life (VSL) across potential wage levels in panel data using quantile regressions with intercept heterogeneity. Latent heterogeneity is econometrically important and affects the estimated VSL. Our findings indicate that a reasonable average cost per expected life saved cut-off for health and safety regulations is 7 million to7 million to 8 million per life saved, but the VSL varies considerably across the labor force. Our results reconcile the previous discrepancies between hedonic VSL estimates and the values implied by theories linked to the coefficient of relative risk aversion. Because the VSL varies elastically with income, regulatory agencies should regularly update the VSL used in benefit assessments, increasing the VSL proportionally with changes in income over time.  相似文献   
823.
824.
Abstract

One or two session psychotherapy has a long history, and well-known practitioners have made use of it. Favorable results have been reasonably well documented. Often it has been done out of necessity, less frequently because all were satisfied that it sufficed. Problems that lend themselves to one or two sessions are: psychological work which has already been done but for which affirmation is sought, requests for diagnostic evaluation, and less often but more challenging, intrapsychic conflict requiring uncovering work. Patient characteristics and therapist attitudes are discussed. For one or two sessions of treatment to occur the therapist must be alert to the possibility, must assess quickly when a case is in hand, set the process in motion, and determine a satisfactory stopping point. It is suggested that the college population lends itself especially well to one or two sessions of psychotherapy, not only from the standpoint of the limited resources of many student health services but also for the ego strengthening potential it provides.  相似文献   
825.
Extract

I have suggested that at a given birth order the probability of having a further pregnancy is greater when the last pregnancy had been spontaneously aborted than when it resulted in a birth.2 Léridon,3in the course of a valuable paper on foetal wastage, presents data which, according to him, impugn my suggestion. I would like to question his claim.  相似文献   
826.
Lot resubmissions are allowed in situations where the original inspection results are suspected or when the supplier is allowed to opt for resampling as per the provisions of the contract etc. This paper examines the situation of resampling of lots and derives the performance measures of a resampling scheme having a single sampling plan for inspection. The usefulness and limitations of resampling of resubmitted lots are also discussed  相似文献   
827.
828.
829.
830.
Abstract

The present study examines the stability of bright light circadian readjustment during two consecutive dim light night-work periods and circadian synchronization during the recovery after a night-shift period. A sample of 10 subjects was divided into 2 groups (control group: 6 subjects; experimental group: 4 subjects). All subjects worked during 5 days, between 23:00 and 07:00 h and then went to sleep. Subjects received 2500-3000 lux between 02:00 and 05:00 h during 5 days for the control group and 3 days for the experimental group. During recovery after the night-shift periods, three cycles of bright light were administered at two different times: 12:00-15:00 h for two of six subjects from the control group and 10:00-13:00 h for all subjects (4) of the experimental group. By the fifth cycle of night-work the maximum of urinary aMT6s excretion that occurs at 05:00 h in the baseline condition was shifted to 12:00 h for the control and experimental groups (delay in hours: 7±1.6 (control); 7±1 (experimental)). This result suggests that three cycles of bright light are sufficient to induce a significant phase delay and that this delay remained stable when night-work proceeded under dim light. The phase delay of the circadian aMT6s excretion by exposure to bright light was accompanied by an improvement of the quality of day sleep and level of cognitive and psychomotor performances for control and experimental groups. No significant difference was observed in the two groups for daytime sleep and nocturnal performance. The two bright light periods used during the three days of recovery induced a complete synchronization in five of six subjects. One subject showed a partial synchronization probably because he remained at the laboratory under dim light during the day and had few family and social contacts.  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