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   13078篇
  免费   401篇
  国内免费   15篇
管理学   1602篇
民族学   80篇
人才学   1篇
人口学   1143篇
丛书文集   143篇
理论方法论   1220篇
综合类   690篇
社会学   6961篇
统计学   1654篇
  2023年   70篇
  2021年   107篇
  2020年   207篇
  2019年   253篇
  2018年   328篇
  2017年   476篇
  2016年   323篇
  2015年   264篇
  2014年   311篇
  2013年   2049篇
  2012年   479篇
  2011年   464篇
  2010年   392篇
  2009年   328篇
  2008年   400篇
  2007年   412篇
  2006年   416篇
  2005年   361篇
  2004年   285篇
  2003年   252篇
  2002年   267篇
  2001年   338篇
  2000年   281篇
  1999年   273篇
  1998年   201篇
  1997年   168篇
  1996年   158篇
  1995年   172篇
  1994年   158篇
  1993年   162篇
  1992年   185篇
  1991年   186篇
  1990年   183篇
  1989年   159篇
  1988年   168篇
  1987年   191篇
  1986年   147篇
  1985年   157篇
  1984年   175篇
  1983年   151篇
  1982年   151篇
  1981年   121篇
  1980年   111篇
  1979年   122篇
  1978年   95篇
  1977年   79篇
  1976年   93篇
  1975年   109篇
  1974年   84篇
  1972年   62篇
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
811.
Abstract

Background: Young adults remain the earliest legal target for the tobacco industry. Against this, the existence of smoking policies would appear to offer some protection to students on campus. However, little research has been conducted into the outcomes of such policies from a student perspective. Methods: The authors conducted 8 focus groups at 4 selected Canadian undergraduate campuses to investigate student perceptions and behaviors resulting from campus smoking policies. Results: Results indicated that student smoking behaviors are minimally impacted by campus smoking policies due to seriously compromised implementation and enforcement. Conclusions: These findings imply that the presence of campus smoking policies and claims of “smoke-free” campuses should not be misinterpreted as achievement and without renewed focus and adequate tobacco control infrastructure, it will remain possible for young adults to initiate and maintain tobacco smoking on campus.  相似文献   
812.
This study explored South Korean college students' career compromise processes and examined whether preferences for sex type, prestige, or interests would be differentiated by Holland theme interest types, gender, or college major. Participants were South Korean undergraduate students from 2 universities in Seoul, South Korea. They were asked to choose 1 occupation from each of 168 pairs of occupations using a forced‐choice format. A total of 376 surveys were analyzed. There were significant main effects for Holland interest types and for gender but not for college major on their career compromise processes. Implications for career counselors and researchers are discussed.  相似文献   
813.
“One method of error analysis (not the one we will use) is based upon the principles of mathematical statistics. Unfortunately, statistical methods can only be meaningfully applied when one has large amounts of data for a given system. In many cases … these large quantities of data are not available … then statistical methods are not applicable, and some other methods must be devised.”  相似文献   
814.
A percentile point simulation algorithm is presented. The algorithm is useful when computer storage and time considerations are at a premium. The algorithm employs various time- and storage-saving ideas, including a “pinching” mechanism that reduces the proportion of simulated values stored as the number of iterations is increased. Algorithm output includes a measure of precision as well as the simulated percentile point. The simulation can be stopped when the desired degree of precision has been attained.  相似文献   
815.
In this paper, an alternative method for the comparison of two diagnostic systems based on receiver operating characteristic (ROC) curves is presented. ROC curve analysis is often used as a statistical tool for the evaluation of diagnostic systems. However, in general, the comparison of ROC curves is not straightforward, in particular, when they cross each other. A similar difficulty is also observed in the multi-objective optimization field where sets of solutions defining fronts must be compared with a multi-dimensional space. Thus, the proposed methodology is based on a procedure used to compare the performance of distinct multi-objective optimization algorithms. In general, methods based on the area under the ROC curves are not sensitive to the existence of crossing points between the curves. The new approach can deal with this situation and also allows the comparison of partial portions of ROC curves according to particular values of sensitivity and specificity of practical interest. Simulations results are presented. For illustration purposes, considering real data from newborns with very low birthweight, the new method was applied in order to discriminate the better index for evaluating the risk of death.  相似文献   
816.
The boxplot is an effective data-visualization tool useful in diverse applications and disciplines. Although more sophisticated graphical methods exist, the boxplot remains relevant due to its simplicity, interpretability, and usefulness, even in the age of big data. This article highlights the origins and developments of the boxplot that is now widely viewed as an industry standard as well as its inherent limitations when dealing with data from skewed distributions, particularly when detecting outliers. The proposed Ratio-Skewed boxplot is shown to be practical and suitable for outlier labeling across several parametric distributions.  相似文献   
817.
818.
819.
Abstract

To increase the effectiveness and efficiency of searches for information, accounting students, researchers, practitioners, and regulators could benefit from a Website devoted to the electronic access to journals. The site described here addresses such a need in the business discipline of accounting. On the site, the titles of over 470 journals are listed and categorized by topical areas within accounting. Then, within each accounting category, the journals are grouped according to their Internet accessibility. To provide the user with quick access to the various journals, the site provides links to the homepages of the various journals. Serials Review 2002; 28:201–205.  相似文献   
820.
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