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   15545篇
  免费   479篇
  国内免费   15篇
管理学   1970篇
民族学   97篇
人才学   1篇
人口学   1313篇
丛书文集   153篇
教育普及   1篇
理论方法论   1514篇
综合类   711篇
社会学   8261篇
统计学   2018篇
  2023年   89篇
  2021年   120篇
  2020年   246篇
  2019年   338篇
  2018年   395篇
  2017年   567篇
  2016年   393篇
  2015年   327篇
  2014年   399篇
  2013年   2465篇
  2012年   568篇
  2011年   548篇
  2010年   463篇
  2009年   392篇
  2008年   474篇
  2007年   490篇
  2006年   485篇
  2005年   436篇
  2004年   358篇
  2003年   313篇
  2002年   328篇
  2001年   398篇
  2000年   326篇
  1999年   330篇
  1998年   239篇
  1997年   207篇
  1996年   193篇
  1995年   204篇
  1994年   191篇
  1993年   189篇
  1992年   211篇
  1991年   215篇
  1990年   205篇
  1989年   177篇
  1988年   198篇
  1987年   214篇
  1986年   180篇
  1985年   179篇
  1984年   199篇
  1983年   173篇
  1982年   168篇
  1981年   148篇
  1980年   128篇
  1979年   143篇
  1978年   112篇
  1977年   89篇
  1976年   105篇
  1975年   122篇
  1974年   90篇
  1972年   67篇
排序方式: 共有10000条查询结果,搜索用时 644 毫秒
961.
A 2009 national telephone survey of 924 U.S. adults assessed perceptions of terrorism and homeland security issues. Respondents rated severity of effects, level of understanding, number affected, and likelihood of four terrorist threats: poisoned water supply; explosion of a small nuclear device in a major U.S. city; an airplane attack similar to 9/11; and explosion of a bomb in a building, train, subway, or highway. Respondents rated perceived risk and willingness to pay (WTP) for dealing with each threat. Demographic, attitudinal, and party affiliation data were collected. Respondents rated bomb as highest in perceived risk but gave the highest WTP ratings to nuclear device. For both perceived risk and WTP, psychometric variables were far stronger predictors than were demographic ones. OLS regression analyses using both types of variables to predict perceived risk found only two significant demographic predictors for any threat—Democrat (a negative predictor for bomb) and white male (a significant positive predictor for airline attack). In contrast, among psychometric variables, severity, number affected, and likelihood were predictors of all four threats and level of understanding was a predictor for one. For WTP, education was a negative predictor for three threats; no other demographic variables were significant predictors for any threat. Among psychometric variables, perceived risk and number affected were positive predictors of WTP for all four threats; severity and likelihood were predictors for three; level of understanding was a significant predictor for two.  相似文献   
962.
963.
964.
Despite a 60-plus–year history of international adoption (IA) placements, the body of research exploring counseling and psychological interventions for those affected by IA is still in its infancy. This critical review of the state of the literature addresses research, theory, and practice relevant to the international adoption triad (adoptive parents, birth parents, and adoptees). We highlight the lack of empirical attention to the clinical needs of birth parents, the tendency to overlook the clinical needs of adoptive parents both pre- and post-adoption, early childhood vulnerability in international adoptees, and adolescent identity challenges and the attendant clinical issues.  相似文献   
965.
Abstract

The Student Dental Health Program (SDHP) is an open panel, prepaid dental insurance plan at the University of Alabama in Birmingham. The program was developed primarily to provide optimal dental health service; however the SDHP also serves educational and research functions that are consistent with the objectives of the university. The student bodies of the Schools of Dentistry, Medicine, Nursing, and Optometry constitute the enrollee population.

Total cost rose from $18,418 in 1969–70 with 862 enrollees, to $70,930 in 1975–76 with 1,618 enrollees. During the same period the number of procedures completed increased from 2,868 to 6,796, with the average cost per procedure increasing from $6.42 to $10.44. The number of restorative services declined and preventive services increased. In 1976–77 benefits per student treated were estimated at $80 as compared to the annual fee of $48. The value of unmet needs upon entrance to the program averaged $59 per enrollee in 1974–75. By 1976–77 this figure was reduced to $26 due to implementation of an initial screening. The program is self-supporting due to a variety of cost containment measures. On balance, the program can be considered successful and beneficial to all parties concerned.  相似文献   
966.
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   
967.
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   
968.
“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   
969.
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   
970.
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   
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