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   20383篇
  免费   642篇
  国内免费   1篇
管理学   2737篇
民族学   116篇
人口学   1812篇
丛书文集   79篇
教育普及   1篇
理论方法论   1875篇
综合类   195篇
社会学   10363篇
统计学   3848篇
  2023年   133篇
  2022年   72篇
  2021年   137篇
  2020年   358篇
  2019年   542篇
  2018年   630篇
  2017年   831篇
  2016年   652篇
  2015年   426篇
  2014年   600篇
  2013年   3657篇
  2012年   772篇
  2011年   718篇
  2010年   528篇
  2009年   425篇
  2008年   560篇
  2007年   521篇
  2006年   555篇
  2005年   427篇
  2004年   442篇
  2003年   370篇
  2002年   399篇
  2001年   487篇
  2000年   427篇
  1999年   423篇
  1998年   323篇
  1997年   267篇
  1996年   295篇
  1995年   302篇
  1994年   251篇
  1993年   265篇
  1992年   309篇
  1991年   305篇
  1990年   304篇
  1989年   258篇
  1988年   251篇
  1987年   209篇
  1986年   231篇
  1985年   260篇
  1984年   223篇
  1983年   196篇
  1982年   169篇
  1981年   134篇
  1980年   162篇
  1979年   175篇
  1978年   136篇
  1977年   117篇
  1976年   89篇
  1975年   102篇
  1974年   98篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
52.
Welfare reform was examined for 39 Michigan families whose children have significant health or intellectual and behavioral disabilities. As a group, these families received little specialized assistance or services to address their unique needs. Family-cited barriers to self-sufficiency included poorly trained welfare caseworkers, limited public transportation, and inadequate child care. Having an older child was the only discriminating variable between working and non-working mothers. However, working mothers only had temporary positions with no benefits and low pay. All families, whether employed or not, lived below the poverty line.  相似文献   
53.
National Park of Tijuca in Rio de Janeiro (Brazil) is about 3,300 ha and considered the largest urban forest in the world. Its floristic composition is typical of Atlantic Rain Forest. The reserve is being altered because of fire occurrences and urban expansion. This study identified locations and causes of forest fires, and makes management recommendations to restore damaged areas. From 1991 to 2000, forest firefighters recorded an average of 75-fire occurrences/year. Identified causes included hot air balloons (24%), intentional (24%), rubbish burning (21%) and religious practices (17%). Primary fuels included invasive grasses and ferns. Although hot air balloons destroyed larger areas of forest in each occurrence, a greater number of fires started in the invasive vegetation along roads that bisect the forest. In response to recurrent forests, invasive vegetation has spread gradually into the forest increasing forest degradation. To decrease fire damage, sites with high fire frequencies and density of invasive vegetation were planted with less flammable species. Results indicate that fire frequency decreased and density of invasive vegetation declined. This approach appears to prevent fire incidence, reduce the need for fire fighting, and preserve existing biodiversity.  相似文献   
54.
Tolerating Force: A Contextual Analysis of the Meaning of Tolerance   总被引:1,自引:0,他引:1  
This study employs college student survey data to examine the specific social conditions that influence tolerance of the use of force against children. The findings reveal that a certain ambivalence exists regarding parental force to control the behavior of children. Although the respondents are tolerant of parental force used to counteract disrespectful provocations by children, they are less tolerant of force used to counteract age-related misbehaviors. Implications of these findings are discussed in light of current and future social and family policy.  相似文献   
55.
The sociocultural content of foreign language textbooks has become a concern of scholars and practitioners owing to the fact that the traditional emphasis on purely linguistic issues has been expanded to embrace a language in context approach. This paper studies the English‐speaking communities that are described in English language teaching textbooks marketed in Spain. It examines to what extent an international and/or intercultural approach is a constituent element in their design.  相似文献   
56.
This paper outlines the conceptual bases, strategies, and psychological attributes of leadership by self-leadership. In addition, relations to other theories of leadership are drawn. Dimensions and correlates of self-leadership competence are described and discussed. Various approaches for developing self-leadership competence are discussed as well.  相似文献   
57.
58.
Complete and partial diallel cross designs are examined as to their construction and robustness against the loss of a block of observations. A simple generalized inverse is found for the information matrix of the line effects, which allows evaluation of expressions for the variances of the line-effect differences with and without the missing block. A-efficiencies, based on average variances of the elementary contrasts of the line-effects, suggest that these designs are fairly robust. The loss of efficiency is generally less than 10%, but it is shown that specific comparisons might suffer a loss of efficiency of as much as 40%.  相似文献   
59.
Parameter design or robust parameter design (RPD) is an engineering methodology intended as a cost-effective approach for improving the quality of products and processes. The goal of parameter design is to choose the levels of the control variables that optimize a defined quality characteristic. An essential component of RPD involves the assumption of well estimated models for the process mean and variance. Traditionally, the modeling of the mean and variance has been done parametrically. It is often the case, particularly when modeling the variance, that nonparametric techniques are more appropriate due to the nature of the curvature in the underlying function. Most response surface experiments involve sparse data. In sparse data situations with unusual curvature in the underlying function, nonparametric techniques often result in estimates with problematic variation whereas their parametric counterparts may result in estimates with problematic bias. We propose the use of semi-parametric modeling within the robust design setting, combining parametric and nonparametric functions to improve the quality of both mean and variance model estimation. The proposed method will be illustrated with an example and simulations.  相似文献   
60.
Many applications of nonparametric tests based on curve estimation involve selecting a smoothing parameter. The author proposes an adaptive test that combines several generalized likelihood ratio tests in order to get power performance nearly equal to whichever of the component tests is best. She derives the asymptotic joint distribution of the component tests and that of the proposed test under the null hypothesis. She also develops a simple method of selecting the smoothing parameters for the proposed test and presents two approximate methods for obtaining its P‐value. Finally, she evaluates the proposed test through simulations and illustrates its application to a set of real 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