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   10801篇
  免费   340篇
  国内免费   1篇
管理学   1360篇
民族学   88篇
人才学   1篇
人口学   1205篇
丛书文集   36篇
理论方法论   937篇
综合类   152篇
社会学   5180篇
统计学   2183篇
  2023年   109篇
  2022年   73篇
  2021年   114篇
  2020年   263篇
  2019年   332篇
  2018年   483篇
  2017年   555篇
  2016年   431篇
  2015年   259篇
  2014年   376篇
  2013年   1937篇
  2012年   483篇
  2011年   315篇
  2010年   256篇
  2009年   224篇
  2008年   242篇
  2007年   208篇
  2006年   226篇
  2005年   200篇
  2004年   194篇
  2003年   171篇
  2002年   192篇
  2001年   190篇
  2000年   191篇
  1999年   187篇
  1998年   159篇
  1997年   149篇
  1996年   143篇
  1995年   124篇
  1994年   116篇
  1993年   114篇
  1992年   126篇
  1991年   136篇
  1990年   130篇
  1989年   149篇
  1988年   87篇
  1987年   115篇
  1986年   97篇
  1985年   120篇
  1984年   101篇
  1983年   104篇
  1982年   82篇
  1981年   84篇
  1980年   78篇
  1979年   82篇
  1978年   85篇
  1977年   60篇
  1976年   66篇
  1975年   64篇
  1974年   60篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
The construct, family resilience, has been defined and applied very differently by those who are primarily clinical practitioners and those who are primarily researchers in the family field. In thisarticle, the family resilience perspective is integrated with conceptual definitions from family stress theory using the Family Adjustment and Adaptation Response (FAAR) Model in an effort to clarify distinctions between family resiliency as capacity and family resilience as a process. The family resilience process is discussed in terms of (a) the meaning of significant risk exposure (vs. the normal challenges of family life) and (b) the importance of making conceptual and operational distinctions between family system outcomes and family protective processes. Recommendations for future family resilience research are discussed.  相似文献   
25.
26.
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   
27.
Spatial variation in soil inorganic nitrogen across an arid urban ecosystem   总被引:4,自引:1,他引:3  
We explored variations in inorganic soil nitrogen (N) concentrations across metropolitan Phoenix, Arizona, and the surrounding desert using a probability-based synoptic survey. Data were examined using spatial statistics on the entire region, as well as for the desert and urban sites separately. Concentrations of both NO3-N and NH4-N were markedly higher and more heterogeneous amongst urban compared to desert soils. Regional variation in soil NO3-N concentration was best explained by latitude, land use history, population density, along with percent cover of impervious surfaces and lawn, whereas soil NH4-N concentrations were related to only latitude and population density. Within the urban area, patterns in both soil NO3-N and NH4-N were best predicted by elevation, population density and type of irrigation in the surrounding neighborhood. Spatial autocorrelation of soil NO3-N concentrations explained 49% of variation among desert sites but was absent between urban sites. We suggest that inorganic soil N concentrations are controlled by a number of ‘local’ or ‘neighborhood’ human-related drivers in the city, rather than factors related to an urban-rural gradient.  相似文献   
28.
It is well-known that, under Type II double censoring, the maximum likelihood (ML) estimators of the location and scale parameters, θ and δ, of a twoparameter exponential distribution are linear functions of the order statistics. In contrast, when θ is known, theML estimator of δ does not admit a closed form expression. It is shown, however, that theML estimator of the scale parameter exists and is unique. Moreover, it has good large-sample properties. In addition, sharp lower and upper bounds for this estimator are provided, which can serve as starting points for iterative interpolation methods such as regula falsi. Explicit expressions for the expected Fisher information and Cramér-Rao lower bound are also derived. In the Bayesian context, assuming an inverted gamma prior on δ, the uniqueness, boundedness and asymptotics of the highest posterior density estimator of δ can be deduced in a similar way. Finally, an illustrative example is included.  相似文献   
29.
30.
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   
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