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   132735篇
  免费   4398篇
  国内免费   1268篇
管理学   2698篇
劳动科学   28篇
民族学   2078篇
人才学   10篇
人口学   1741篇
丛书文集   18238篇
理论方法论   5923篇
综合类   97724篇
社会学   4700篇
统计学   5261篇
  2024年   147篇
  2023年   637篇
  2022年   1208篇
  2021年   1148篇
  2020年   1405篇
  2019年   1303篇
  2018年   1385篇
  2017年   1736篇
  2016年   1922篇
  2015年   2626篇
  2014年   6383篇
  2013年   7532篇
  2012年   7909篇
  2011年   9377篇
  2010年   7674篇
  2009年   7893篇
  2008年   8239篇
  2007年   10471篇
  2006年   10536篇
  2005年   9800篇
  2004年   9296篇
  2003年   8933篇
  2002年   7209篇
  2001年   5961篇
  2000年   3516篇
  1999年   1007篇
  1998年   490篇
  1997年   404篇
  1996年   358篇
  1995年   300篇
  1994年   217篇
  1993年   188篇
  1992年   154篇
  1991年   129篇
  1990年   71篇
  1989年   64篇
  1988年   74篇
  1987年   24篇
  1986年   27篇
  1985年   101篇
  1984年   112篇
  1983年   87篇
  1982年   80篇
  1981年   70篇
  1980年   55篇
  1979年   59篇
  1978年   49篇
  1977年   16篇
  1976年   11篇
  1975年   6篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
31.
《Long Range Planning》2019,52(5):101825
Research on problemistic search has assumed negative attainment discrepancy to be the trigger of both local and distant search. Extending this research, we present and compare two additional triggers: (1) relative attainment discrepancy, which reflects how much a firm's attainment discrepancy deviates from its past negative attainment discrepancies; and (2) persistent attainment discrepancy, which reflects how often the firm experiences below-aspirations performance. Our triggers for distant search model a behavioral explanation for the timing and relatedness of acquisitions. We find support for baseline arguments of problemistic search whereby firms increase both industry- and skill-related acquisitions when they perform below aspirations. When they persistently perform below aspirations, however, this likelihood is reduced and firms engage in acquisitions that are more unrelated, thereby providing support for the notion of expanding search boundaries from local to distant search. Of the two triggers of distant search proposed, relative attainment discrepancy does not induce firms to expand search boundaries. Our results indicate that persistent attainment discrepancy is a key construct to consider when studying the expansion of search boundaries.  相似文献   
32.
While the US Supreme Court was considering two related cases involving the constitutionality of same-sex marriage, one major question informing that decision was whether scientific research had achieved consensus regarding how children of same-sex couples fare. Determining the extent of consensus has become a key aspect of how social science evidence and testimony is accepted by the courts. Here, we show how a method of analyzing temporal patterns in citation networks can be used to assess the state of social scientific literature as a means to inform just such a question. Patterns of clustering within these citation networks reveal whether and when consensus arises within a scientific field. We find that the literature on outcomes for children of same-sex parents is marked by scientific consensus that they experience “no differences” compared to children from other parental configurations.  相似文献   
33.
When a candidate predictive marker is available, but evidence on its predictive ability is not sufficiently reliable, all‐comers trials with marker stratification are frequently conducted. We propose a framework for planning and evaluating prospective testing strategies in confirmatory, phase III marker‐stratified clinical trials based on a natural assumption on heterogeneity of treatment effects across marker‐defined subpopulations, where weak rather than strong control is permitted for multiple population tests. For phase III marker‐stratified trials, it is expected that treatment efficacy is established in a particular patient population, possibly in a marker‐defined subpopulation, and that the marker accuracy is assessed when the marker is used to restrict the indication or labelling of the treatment to a marker‐based subpopulation, ie, assessment of the clinical validity of the marker. In this paper, we develop statistical testing strategies based on criteria that are explicitly designated to the marker assessment, including those examining treatment effects in marker‐negative patients. As existing and developed statistical testing strategies can assert treatment efficacy for either the overall patient population or the marker‐positive subpopulation, we also develop criteria for evaluating the operating characteristics of the statistical testing strategies based on the probabilities of asserting treatment efficacy across marker subpopulations. Numerical evaluations to compare the statistical testing strategies based on the developed criteria are provided.  相似文献   
34.
Drawing from the theory of policy voting, this study examines the impact of opinions about gay rights on voting for presidential candidates. Qualitative analysis of the major party platforms and candidate campaign rhetoric from the six presidential elections held between 1988 and 2008 indicates that Democratic and Republican presidential candidates began openly expressing opposing positions on gay rights issues in 1992. Quantitative analysis of public opinion shows that, starting in 1992 and continuing through 2008, gay rights issues became more salient to the public, and opinions about gay rights began to exert a significant effect on vote choice. The study concludes with a discussion of the partisan forces that shaped the electoral significance of gay rights issues during the period from 1988 to 2008 and speculation about the role of gay rights issues in shaping future partisan electoral strategy.  相似文献   
35.
We consider a method of moments approach for dealing with censoring at zero for data expressed in levels when researchers would like to take logarithms. A Box–Cox transformation is employed. We explore this approach in the context of linear regression where both dependent and independent variables are censored. We contrast this method to two others, (1) dropping records of data containing censored values and (2) assuming normality for censored observations and the residuals in the model. Across the methods considered, where researchers are interested primarily in the slope parameter, estimation bias is consistently reduced using the method of moments approach.  相似文献   
36.
科技企业是实现科技创新的驱动者和科技成果转化的重要载体,也是推动研究开发的重要参与者,科学评价科技企业创新能力有助于企业自身不断发展壮大。在分析国内外新区科技企业创新驱动发展相关理论研究的基础上,从研发投入、研发基础、研发效益和现代科技四个角度,运用层次分析法构建科技企业创新能力评价系统,并通过实证分析说明评价系统的可靠性;根据评价系统测算出现阶段雄安新区科技企业创新能力,通过与成熟新区科技企业的比较,发现其短板和不足,力图为决策者科学合理评价、管理科技企业创新发展提供有益参考。  相似文献   
37.
2012年3D 版《泰坦尼克号》的华丽上映曾掀起影迷们对它的新一轮热捧。文章就同样备受中国观众喜爱的中国方言版《泰坦尼克号》为案例,结合功能目的论来探寻中国方言版字幕翻译的目的与性质,进而分析、总结英文影片字幕的中国方言版译制活动过程。  相似文献   
38.
随着勘探程度的深入,为了扩大四川盆地天然气勘探领域、寻找新的勘探接替区,四川盆地的勘探区域由盆内逐渐向盆缘延伸。在这种背景下,川东北地区须家河组二段相继取得新的勘探成果,但在勘探开发过程中逐渐暴露了诸如区块之间气井产能差异大,储层的碎屑组分、结构及厚度、物性、孔隙结构差异明显等问题,制约了勘探开发的步伐。针对上述问题,根据岩芯观察描述、分析化验资料及测井解释成果,从沉积、成岩方面入手,对比剖析了川东北龙岗和营山地区须二段储层特征的差异性及其成因,认为远离物源区和高能水体的反复淘洗是造成储层差异性的首要因素,强烈的压实作用和多期石英加大对储层差异性起关键作用,自生绿泥石衬边胶结和长石选择性溶蚀最终决定了储层差异性。从而解释了气藏勘探开发中遇到的诸多问题,对有效指导该区的下一步勘探开发工作具有重要意义。  相似文献   
39.
Despite the popularity and importance, there is limited work on modelling data which come from complex survey design using finite mixture models. In this work, we explored the use of finite mixture regression models when the samples were drawn using a complex survey design. In particular, we considered modelling data collected based on stratified sampling design. We developed a new design-based inference where we integrated sampling weights in the complete-data log-likelihood function. The expectation–maximisation algorithm was developed accordingly. A simulation study was conducted to compare the new methodology with the usual finite mixture of a regression model. The comparison was done using bias-variance components of mean square error. Additionally, a simulation study was conducted to assess the ability of the Bayesian information criterion to select the optimal number of components under the proposed modelling approach. The methodology was implemented on real data with good results.  相似文献   
40.
Although still a neglected area, over the years a growing body of sociological research on the position of ethno-racial minorities in Western artistic fields has emerged. With this article we aim to contribute to this research area by focusing on ethno-racial diversity in the Dutch literary field. Through in-depth interviews, we analyse how gatekeepers mobilise specific cultural repertoires and by doing so draw ethno-racial boundaries when discussing acquisition, assessing quality and positioning themselves in the literary field. We argue that literary publishers and other professionals (selectively) employ an ‘old school’ modernist repertoire that especially values the formal aspects of literary products, by which non-white writers and publishers concerned with diversity are often positioned in an identity politics framework. Their work is said to take in a less prestigious ‘political’/’subjective’ position rather than a ‘literary’/‘universal’ one. As such, this paper informs on how gatekeepers’ practices shape the position of non-white authors in the Dutch literary field.  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