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   89144篇
  免费   2927篇
  国内免费   5篇
管理学   12308篇
民族学   542篇
人才学   26篇
人口学   6788篇
丛书文集   528篇
理论方法论   9327篇
综合类   2192篇
社会学   41655篇
统计学   18710篇
  2023年   500篇
  2021年   566篇
  2020年   1496篇
  2019年   2195篇
  2018年   2047篇
  2017年   3109篇
  2016年   2358篇
  2015年   2032篇
  2014年   2612篇
  2013年   18784篇
  2012年   2326篇
  2011年   2129篇
  2010年   1958篇
  2009年   2178篇
  2008年   2002篇
  2007年   1838篇
  2006年   2075篇
  2005年   2267篇
  2004年   2137篇
  2003年   1863篇
  2002年   1968篇
  2001年   1964篇
  2000年   1744篇
  1999年   1653篇
  1998年   1484篇
  1997年   1322篇
  1996年   1305篇
  1995年   1314篇
  1994年   1280篇
  1993年   1272篇
  1992年   1250篇
  1991年   1184篇
  1990年   1159篇
  1989年   1005篇
  1988年   1109篇
  1987年   977篇
  1986年   863篇
  1985年   1046篇
  1984年   1105篇
  1983年   995篇
  1982年   922篇
  1981年   835篇
  1980年   798篇
  1979年   862篇
  1978年   760篇
  1977年   685篇
  1976年   647篇
  1975年   627篇
  1974年   509篇
  1973年   436篇
排序方式: 共有10000条查询结果,搜索用时 781 毫秒
561.
The visible and political gay community has been characterized as an increasingly middle-class, white institution. It is hypothesized that this middle-class nature requires economic and psychosocial resources that are not available to the working class and, thus, may limit the expression of sexual orientation for the working class. An analysis of data from the multicity Urban Men's Health Study supports this hypothesis. Nine of 14 hypothesized effects are statistically significant and indicate that working-class men who are homosexually active are less likely to describe themselves as gay, are more likely to have heterosexual experience, and are less likely to be involved in the gay community. Thus, it is important to incorporate class differences when addressing the social and the political dynamics of sexual orientation.  相似文献   
562.
This paper presents a method of estimating a receiver operating characteristic (ROC) curve when the underlying diagnostic variable X is continuous and fully observed. The new method is based on modelling the probability of response given X , rather than the distribution of X given response. The method offers advantages in modelling flexibility and computational simplicity. The resulting ROC curve estimates are semi-parametric and can, in principle, take an infinite variety of shapes. Moreover, model selection can be based on standard methods within the binomial regression framework. Statistical accuracy of the curve estimate is provided by a simply implemented bootstrap approach.  相似文献   
563.
In this paper we develop a study on several types of parallel genetic algorithms (PGAs). Our motivation is to bring some uniformity to the proposal, comparison, and knowledge exchange among the traditionally opposite kinds of serial and parallel GAs. We comparatively analyze the properties of steady-state, generational, and cellular genetic algorithms. Afterwards, this study is extended to consider a distributed model consisting in a ring of GA islands. The analyzed features are the time complexity, selection pressure, schema processing rates, efficacy in finding an optimum, efficiency, speedup, and resistance to scalability. Besides that, we briefly discuss how the migration policy affects the search. Also, some of the search properties of cellular GAs are investigated. The selected benchmark is a representative subset of problems containing real world difficulties. We often conclude that parallel GAs are numerically better and faster than equivalent sequential GAs. Our aim is to shed some light on the advantages and drawbacks of various sequential and parallel GAs to help researchers using them in the very diverse application fields of the evolutionary computation.  相似文献   
564.
565.
566.
在日语学习中,因受语言环境和学习方法的限制,听力被认为是提高日语水平和成绩的一大难关。作者遵循听觉系统中听力的解码理论,以一年一度的国际日本语能力测试题为例,提出并具体分析了提高日语听力的三种模式———预测法、捕捉法和贯穿法,并指出运用这些技巧时应注意的几个问题。期望学习者能克服心理障碍,讲究科学的方法,把这些模式积极运用到平时的训练和测试中去,以此来提高日语听力水平和成绩。  相似文献   
567.
College students (20 women, 14 men) seeking career counseling services at a university career center participated in this exploratory investigation. A 2 (DISCOVER treatment) × 2 (counseling treatment) research design was used to evaluate the individual and combined effects of DISCOVER (ACT, 1998) and counseling on participants' career decision‐making self‐efficacy and career decision‐making attributional style. Findings revealed a significant effect of the use of DISCOVER on participants' career decision‐making self‐efficacy and their sense of control over the career decision‐making process. Results are discussed regarding the implications for career counseling and ideas for further research in this domain.  相似文献   
568.
569.
Summary.  We define residuals for point process models fitted to spatial point pattern data, and we propose diagnostic plots based on them. The residuals apply to any point process model that has a conditional intensity; the model may exhibit spatial heterogeneity, interpoint interaction and dependence on spatial covariates. Some existing ad hoc methods for model checking (quadrat counts, scan statistic, kernel smoothed intensity and Berman's diagnostic) are recovered as special cases. Diagnostic tools are developed systematically, by using an analogy between our spatial residuals and the usual residuals for (non-spatial) generalized linear models. The conditional intensity λ plays the role of the mean response. This makes it possible to adapt existing knowledge about model validation for generalized linear models to the spatial point process context, giving recommendations for diagnostic plots. A plot of smoothed residuals against spatial location, or against a spatial covariate, is effective in diagnosing spatial trend or co-variate effects. Q – Q -plots of the residuals are effective in diagnosing interpoint interaction.  相似文献   
570.
We discuss the issue of using benchmark doses for quantifying (excess) risk associated with exposure to environmental hazards. The paradigm of low-dose risk estimation in dose-response modeling is used as the primary application scenario. Emphasis is placed on making simultaneous inferences on benchmark doses when data are in the form of proportions, although the concepts translate easily to other forms of outcome data.  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