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   93023篇
  免费   3052篇
  国内免费   3篇
管理学   12907篇
民族学   560篇
人才学   26篇
人口学   7295篇
丛书文集   532篇
教育普及   1篇
理论方法论   9665篇
综合类   2179篇
社会学   43618篇
统计学   19295篇
  2023年   533篇
  2021年   594篇
  2020年   1558篇
  2019年   2306篇
  2018年   2228篇
  2017年   3324篇
  2016年   2494篇
  2015年   2118篇
  2014年   2724篇
  2013年   19282篇
  2012年   2531篇
  2011年   2324篇
  2010年   2080篇
  2009年   2265篇
  2008年   2135篇
  2007年   1970篇
  2006年   2213篇
  2005年   2346篇
  2004年   2231篇
  2003年   1952篇
  2002年   2081篇
  2001年   2032篇
  2000年   1815篇
  1999年   1711篇
  1998年   1518篇
  1997年   1367篇
  1996年   1329篇
  1995年   1353篇
  1994年   1311篇
  1993年   1301篇
  1992年   1304篇
  1991年   1215篇
  1990年   1183篇
  1989年   1051篇
  1988年   1123篇
  1987年   997篇
  1986年   912篇
  1985年   1075篇
  1984年   1153篇
  1983年   1031篇
  1982年   945篇
  1981年   874篇
  1980年   836篇
  1979年   887篇
  1978年   792篇
  1977年   704篇
  1976年   679篇
  1975年   662篇
  1974年   527篇
  1973年   444篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
761.
762.
763.
Annual concentrations of toxic air contaminants are of primary concern from the perspective of chronic human exposure assessment and risk analysis. Despite recent advances in air quality monitoring technology, resource and technical constraints often impose limitations on the availability of a sufficient number of ambient concentration measurements for performing environmental risk analysis. Therefore, sample size limitations, representativeness of data, and uncertainties in the estimated annual mean concentration must be examined before performing quantitative risk analysis. In this paper, we discuss several factors that need to be considered in designing field-sampling programs for toxic air contaminants and in verifying compliance with environmental regulations. Specifically, we examine the behavior of SO2, TSP, and CO data as surrogates for toxic air contaminants and as examples of point source, area source, and line source-dominated pollutants, respectively, from the standpoint of sampling design. We demonstrate the use of bootstrap resampling method and normal theory in estimating the annual mean concentration and its 95% confidence bounds from limited sampling data, and illustrate the application of operating characteristic (OC) curves to determine optimum sample size and other sampling strategies. We also outline a statistical procedure, based on a one-sided t-test, that utilizes the sampled concentration data for evaluating whether a sampling site is compliance with relevant ambient guideline concentrations for toxic air contaminants.  相似文献   
764.
UNDERSTANDING MAIL SURVEY RESPONSE BEHAVIOR A META-ANALYSIS   总被引:5,自引:0,他引:5  
A meta-analysis of prior studies of techniques designed to inducemail survey response rates was conducted. Research encompassing184 effects (study outcomes) in 115 studies (articles) for 17predictors of response rate was examined. The average effectsize across all manipulations was r=.065, indicating an averageincrease of about 6.5 percent in response rates for manipulations.Effect sizes for specific predictors and two potential moderatorsof effects were examined. Results indicated that repeated contactsin the form of preliminary notification and follow-ups, appeals,inclusion of a return envelope, postage, and monetary incentives,were effective in increasing survey response rates. Significanteffect sizes for the predictors ranged from an increase in responseof 2 percent to 31 percent. Implications of the results forthe conduct of mail surveys and future research on mail surveyresponse behavior are discussed.  相似文献   
765.
The importance of client beliefs in career counseling depends on their ability to add unique information about the client over and above that contributed by aptitudes and interests. The Career Beliefs Inventory was administered to 200 Australian students in grade 10 together with measures of Holland's RIASEC interest themes and scholastic aptitudes. The correlations between scales from the three domains showed clearly that beliefs made a contribution distinct from that provided by aptitudes and interests. Even though the results may reflect possible sampling or method variance, career beliefs in this sample added unique information to that traditionally used in career counseling.  相似文献   
766.
Coaching of managers in hospitals as component of a total quality management strategy The author delineates the changed conditions of hospitals at the beginning of the new millenium. In order to be up to date with the growing challenges and the need for change a Total Quality Management (TQM) is necessary. This TQM sees the satisfaction of clients and of employees as crucial for all reorganization processes. The realization in everyday hospital life requires a total personnel development concept, with special regard to the managers and their specific needs for support by supervisors resp. coaches.  相似文献   
767.
Gallup macropartisanship varies more over time than aggregatemeasures of partisanship employing the standard Michigan SurveyResearch Center (SRC) party identification measure, but previousanalyses do not provide direct evidence about why Gallup macropartisanshipis more variable. Although these differences could result fromthe short-term focus of the Gallup party affiliation question,aggregate-level analyses cannot test the effects of questionwording directly. Between March and October 1992, we conducteda series of question-wording experiments, employing six statewidecomputer-assisted telephone interview (CATI) surveys of Michiganadults, including a four-wave panel study. Our analyses stronglysuggest that the Gallup measure responds more to short-termpolitical conditions and clearly demonstrate that the Gallupmeasure is less stable over time. These individual-level resultshelp explain why Gallup macropartisanship varies more over timethan aggregate measures of partisanship employing the standardSRC measure and raise questions about the degree to which onecan generalize from analyses using the Gallup data to the researchliterature on party identification.  相似文献   
768.
A theory of policy differentiation in single issue electoral politics   总被引:1,自引:0,他引:1  
Voter preferences are characterized by a parameter s (say, income) distributed on a set S according to a probability measure F. There is a single issue (say, a tax rate) whose level, b, is to be politically decided. There are two parties, each of which is a perfect agent of some constituency of voters, voters with a given value of s. An equilibrium of the electoral game is a pair of policies, b 1 and b 2, proposed by the two parties, such that b i maximizes the expected utility of the voters whom party i represents, given the policy proposed by the opposition. Under reasonable assumptions, the unique electoral equilibrium consists in both parties proposing the favorite policy of the median voter. What theory can explain why, historically, we observe electoral equilibria where the ‘right’ and ‘left’ parties propose different policies? Uncertainty concerning the distribution of voters is introduced. Let {F(t)} t ε T be a class of probability measures on S; all voters and parties share a common prior that the distribution of t is described by a probability measure H on T. If H has finite support, there is in general no electoral equilibrium. However, if H is continuous, then electoral equilibrium generally exists, and in equilibrium the parties propose different policies. Convergence of equilibrium to median voter politics is proved as uncertainty about the distribution of voter traits becomes small.  相似文献   
769.
The multiple self-referent model (Brown-Collins & Sussewell, 1986) provides a comprehensive framework for understanding the personal, social, and historical aspects of self-concept formation in African American women and has important implications for understanding the complexity of career development issues for Black women. Excerpts from recorded interviews and autobiographical writings of four well-known African American women provide examples of the basic components of this model. Suggested interventions for career counseling with Black female clients are discussed.  相似文献   
770.
The suitability of autoregressive fractionally integrated moving average (ARFIMA) processes for the modeling of US aggregate output is examined. We consider the two most widely used methods for the estimation of the fractionally differencing parameter and discuss the empirical results obtained by applying these methods to the quarterly post-war real GNP as well as to the quarterly post-war real GNP per capita. Contrary to previous findings, we conclude that evidence for a fractional degree of integration is poor.  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