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   40288篇
  免费   1144篇
  国内免费   2篇
管理学   5220篇
民族学   238篇
人才学   6篇
人口学   3692篇
丛书文集   185篇
教育普及   3篇
理论方法论   3671篇
现状及发展   1篇
综合类   449篇
社会学   19860篇
统计学   8109篇
  2023年   222篇
  2022年   172篇
  2021年   247篇
  2020年   656篇
  2019年   1004篇
  2018年   1109篇
  2017年   1485篇
  2016年   1119篇
  2015年   788篇
  2014年   1068篇
  2013年   7063篇
  2012年   1376篇
  2011年   1329篇
  2010年   995篇
  2009年   924篇
  2008年   1111篇
  2007年   1043篇
  2006年   1030篇
  2005年   887篇
  2004年   877篇
  2003年   787篇
  2002年   834篇
  2001年   977篇
  2000年   871篇
  1999年   862篇
  1998年   675篇
  1997年   593篇
  1996年   597篇
  1995年   607篇
  1994年   576篇
  1993年   537篇
  1992年   626篇
  1991年   624篇
  1990年   590篇
  1989年   535篇
  1988年   518篇
  1987年   458篇
  1986年   484篇
  1985年   511篇
  1984年   482篇
  1983年   448篇
  1982年   369篇
  1981年   310篇
  1980年   339篇
  1979年   369篇
  1978年   298篇
  1977年   278篇
  1976年   227篇
  1975年   236篇
  1974年   205篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
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   
62.
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   
63.
As a very small state, Luxembourg would not appear to qualify as an influential foreign policy actor either in Europe or the world. Yet the country's international influence has long belied its reputation as a small state. This article reviews the literature on small-state foreign policy and finds that it offers numerous contradictory conclusions. As a case study it then addresses Luxembourg in the 1990s, with particular attention to two themes: its active participation in the European Union (EU) and its policies directed at maintaining economic prosperity. The paper goes on to explain Luxembourgish foreign policy behaviour through three levels of analysis and assesses to what extent smallness is a benefit or a hindrance to Luxembourg's success in meeting its international goals.  相似文献   
64.
Abstract The effect of nonfarm development on dairy farm survival in New York's highly developed lower Hudson Valley is analyzed. The major hypothesis is that significant losses of dairy farms during this period are the result of urban development pressures. Contrary to this hypothesis, however, the bivariate and multivariate analyses of data from a mail survey of all commercial dairy operators in Dutchess County as of 1984 and industry survivors, exiters, and new entrants through 1990 demonstrate that nonfarm development has a negligible effect on dairy farm survival; rather, survival is significantly affected by age of operator and by family disruption. Thus, demographic and family process factors are found to be more powerful determinants of dairy farm survival in this particular metropolitan context.  相似文献   
65.
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   
66.
67.
68.
A NOTE ON EVANESCENT PROCESSES   总被引:1,自引:0,他引:1  
This note examines the connection between μ-invariant measures for the transition function of a continuous-time Markov chain and those of its q-matrix, Q. The major result establishes a necessary and aufficient condition for a convergent μ-invariant measure for Q to be μ-inhant for the minimal transition function, P, under the assumption that P is honest. This corrects Theorem 6 of Vere-Jones (1969) and the first part of Corollary 1 of Pollett (1986), both of which assert that the above conclusion holds in the absence of this condition. The error was pointed out by E.A. van Doom (1991) and the counterexample which be presented provides the basis for the present arguments. In determining where the error occurred in the original proof, we are able to identify a simple sufficient condition for μ-invariance.  相似文献   
69.
70.
This is a tutorial on the relations between population data and the rates of growth that are calculated from the data. For the calculation of rates of growth, discrete and continuous compounding will be compared so that the reader can see the reasons for using the mathematics of continuous compounding, which is the mathematics of exponential growth. Some properties of exponential growth are developed. Semi-logarithmic graphs will be discussed as a device for representing the size of growing populations and for analyzing the nature of the growth. Illustrative examples will be worked out in order to emphasize applications and utility.  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