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   3242篇
  免费   100篇
  国内免费   1篇
管理学   495篇
民族学   16篇
人才学   1篇
人口学   263篇
丛书文集   25篇
理论方法论   349篇
综合类   33篇
社会学   1748篇
统计学   413篇
  2023年   21篇
  2022年   14篇
  2021年   13篇
  2020年   41篇
  2019年   57篇
  2018年   80篇
  2017年   86篇
  2016年   85篇
  2015年   60篇
  2014年   69篇
  2013年   536篇
  2012年   99篇
  2011年   90篇
  2010年   81篇
  2009年   86篇
  2008年   103篇
  2007年   104篇
  2006年   108篇
  2005年   105篇
  2004年   102篇
  2003年   103篇
  2002年   111篇
  2001年   64篇
  2000年   55篇
  1999年   68篇
  1998年   54篇
  1997年   66篇
  1996年   71篇
  1995年   42篇
  1994年   47篇
  1993年   48篇
  1992年   45篇
  1991年   48篇
  1990年   46篇
  1989年   36篇
  1988年   32篇
  1987年   33篇
  1986年   21篇
  1985年   25篇
  1984年   42篇
  1983年   39篇
  1982年   35篇
  1981年   46篇
  1980年   31篇
  1979年   24篇
  1978年   23篇
  1977年   30篇
  1976年   29篇
  1975年   17篇
  1973年   21篇
排序方式: 共有3343条查询结果,搜索用时 15 毫秒
61.
62.
The vast majority of research on the relationship between corporate governance and strategic management focuses on the impact of corporate governance on strategic management. In this article we propose a cyclical model, highlighting that strategic decisions can also affect corporate governance through shaping firm ownership structure. We discuss the impacts of strategic decisions on firm ownership structure and corporate governance in the contexts of publicly traded firms, private firms, and the privatization of state-owned enterprises. We hope that our cyclical model can promote researchers to develop a more complete view about the relationships between strategic management, ownership structure, and corporate governance.  相似文献   
63.
This paper explores the boundary of the set of reaction networks that have an exact transient (truncated) multidimensional Poisson or product-form distribution for the number of particles of different types. Motivated by the birth–death process, we introduce the notions of transient detailed balance and delay functions, and use these notions to obtain the novel transient product-form distribution in a coagulation-fragmentation process for polymers with a tree-like structure from that of the pure coagulation process.  相似文献   
64.

The main objective of this study was to determine how stream salamander assemblages and species respond to varying levels of impervious surface cover within Maryland’s Piedmont physiographic province. We sampled stream salamanders in 21 first-order streams located in watersheds representing a range of impervious surface cover (0–24 %) across the northeastern part of Maryland’s Piedmont region. Habitat data, including stream substrate and riparian characteristics, were measured at each site. Eurycea bislineata was the predominant species of stream salamander encountered during this study (> 99 % of individuals) and most of these individuals were larvae (> 92 %). Consequently, statistical analysis was limited to E. bislineata larvae. We were unable to detect a difference in E. bislineata abundances or body mass index’s among varying levels of impervious surface cover % or any individual site habitat variables alone. These results suggest that in smaller watersheds within the Piedmont of Maryland, local habitat variables, in conjunction with land use variables, are necessary in determining the abundance and body mass index of E. bislineata larvae populations. This study makes a strong case for halting the over-simplification of the relationship between urbanization and the presence/abundance of stream salamanders.

  相似文献   
65.
An approach is presented for strengthening middle school standards‐based English language arts (ELA) classroom instruction by infusing theory‐ and research‐supported career development constructs and practices. Over an 8‐week period, 90 urban 7th graders participated in an integrated ELA–career development curriculum. Career agency emerged as an important construct for students. It was related to key markers of ELA achievement (i.e., standardized test scores, grades, and positive change in 6th‐ to 7th‐grade test scores) and elaborated on in nuanced ways by students in their written narratives. Four themes related to career agency were identified in student writings: time perspective, challenges of self‐direction, career development, and social and emotional development. Advantages for students and schools related to synergy, scale, and sustainability are discussed.  相似文献   
66.
We experimentally compare fast and slow decisions in a series of experiments on financial risk taking in three countries involving over 1700 subjects. To manipulate fast and slow decisions, subjects were randomly allocated to responding within 7 seconds (time pressure) or waiting for at least 7 or 20 seconds (time delay) before responding. To control for different effects of time pressure and time delay on measurement noise, we estimate separate parameters for noise and risk preferences within a random utility framework. We find that time pressure increases risk aversion for gains and risk taking for losses compared to time delay, implying that time pressure increases the reflection effect of Prospect Theory. The results for gains are weaker and less robust than the results for losses. We find no significant difference between time pressure and time delay for loss aversion (tested in only one of the experiments). Time delay also leads to less measurement noise than time pressure and unconstrained decisions, and appears to be an effective way of decreasing noise in experiments.  相似文献   
67.
The use of thimerosal preservative in childhood vaccines has been largely eliminated over the past decade in the United States because vaccines have been reformulated in single‐dose vials that do not require preservative. An exception is the inactivated influenza vaccines, which are formulated in both multidose vials requiring preservative and preservative‐free single‐dose vials. As part of an ongoing evaluation by USFDA of the safety of biologics throughout their lifecycle, the infant body burden of mercury following scheduled exposures to thimerosal preservative in inactivated influenza vaccines in the United States was estimated and compared to the infant body burden of mercury following daily exposures to dietary methylmercury at the reference dose established by the USEPA. Body burdens were estimated using kinetic parameters derived from experiments conducted in infant monkeys that were exposed episodically to thimerosal or MeHg at identical doses. We found that the body burden of mercury (AUC) in infants (including low birth weight) over the first 4.5 years of life following yearly exposures to thimerosal was two orders of magnitude lower than that estimated for exposures to the lowest regulatory threshold for MeHg over the same time period. In addition, peak body burdens of mercury following episodic exposures to thimerosal in this worst‐case analysis did not exceed the corresponding safe body burden of mercury from methylmercury at any time, even for low‐birth‐weight infants. Our pharmacokinetic analysis supports the acknowledged safety of thimerosal when used as a preservative at current levels in certain multidose infant vaccines in the United States.  相似文献   
68.
Security of infrastructure is a major concern. Traditional security schedules are unable to provide omnipresent coverage; consequently, adversaries can exploit predictable vulnerabilities to their advantage. Randomized security schedules, which randomly deploy security measures, overcome these limitations, but public perceptions of such schedules have not been examined. In this experiment, participants were asked to make a choice between attending a venue that employed a traditional (i.e., search everyone) or a random (i.e., a probability of being searched) security schedule. The absolute probability of detecting contraband was manipulated (i.e., 1/10, 1/4, 1/2) but equivalent between the two schedule types. In general, participants were indifferent to either security schedule, regardless of the probability of detection. The randomized schedule was deemed more convenient, but the traditional schedule was considered fairer and safer. There were no differences between traditional and random schedule in terms of perceived effectiveness or deterrence. Policy implications for the implementation and utilization of randomized schedules are discussed.  相似文献   
69.
In a wide variety of biomedical and clinical research studies, sample statistics from diagnostic marker measurements are presented as a means of distinguishing between two populations, such as with and without disease. Intuitively, a larger difference between the mean values of a marker for the two populations, and a smaller spread of values within each population, should lead to more reliable classification rules based on this marker. We formalize this intuitive notion by deriving practical, new, closed-form expressions for the sensitivity and specificity of three different discriminant tests defined in terms of the sample means and standard deviations of diagnostic marker measurements. The three discriminant tests evaluated are based, respectively, on the Euclidean distance and the Mahalanobis distance between means, and a likelihood ratio analysis. Expressions for the effects of measurement error are also presented. Our final expressions assume that the diagnostic markers follow independent normal distributions for the two populations, although it will be clear that other known distributions may be similarly analyzed. We then discuss applications drawn from the medical literature, although the formalism is clearly not restricted to that application.  相似文献   
70.
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