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   28902篇
  免费   745篇
  国内免费   3篇
管理学   3881篇
民族学   174篇
人口学   3030篇
丛书文集   92篇
教育普及   1篇
理论方法论   2458篇
综合类   331篇
社会学   14472篇
统计学   5211篇
  2023年   151篇
  2021年   150篇
  2020年   419篇
  2019年   616篇
  2018年   1142篇
  2017年   1342篇
  2016年   1022篇
  2015年   507篇
  2014年   706篇
  2013年   4602篇
  2012年   955篇
  2011年   1187篇
  2010年   919篇
  2009年   769篇
  2008年   921篇
  2007年   950篇
  2006年   678篇
  2005年   629篇
  2004年   620篇
  2003年   537篇
  2002年   516篇
  2001年   607篇
  2000年   572篇
  1999年   521篇
  1998年   424篇
  1997年   369篇
  1996年   381篇
  1995年   396篇
  1994年   356篇
  1993年   364篇
  1992年   409篇
  1991年   419篇
  1990年   425篇
  1989年   359篇
  1988年   372篇
  1987年   308篇
  1986年   340篇
  1985年   359篇
  1984年   341篇
  1983年   308篇
  1982年   250篇
  1981年   203篇
  1980年   235篇
  1979年   271篇
  1978年   218篇
  1977年   177篇
  1976年   166篇
  1975年   134篇
  1974年   161篇
  1973年   110篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
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   
62.
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   
63.
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   
64.
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   
65.
66.
67.
68.
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   
69.
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   
70.
The 1998 Korean Survey of Family Income and Expenditures was used to examine the overall consumption and saving behavior of Korean baby boomers and compared the differences in consumption and saving behavior between older and younger boomers. The t -test results indicated that the younger boomers allocated a significantly higher percentage of their expenditures on food away from home, household appliances, transportation and communication than did the older boomers, whereas the older boomers spent higher amounts and allocated larger budget shares on their children's education than did the younger boomers. The results of Ordinary Least-Squares (OLS) regression analysis showed that, holding other factors constant, older boomers not only spent significantly more in the total consumption expenditures and education expenditures, but older boomers also saved significantly less than did younger boomers.  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