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   400篇
  免费   20篇
各国政治   29篇
工人农民   51篇
世界政治   21篇
外交国际关系   18篇
法律   208篇
中国政治   3篇
政治理论   84篇
综合类   6篇
  2023年   3篇
  2021年   3篇
  2020年   10篇
  2019年   13篇
  2018年   17篇
  2017年   17篇
  2016年   11篇
  2015年   11篇
  2014年   8篇
  2013年   67篇
  2012年   14篇
  2011年   12篇
  2010年   11篇
  2009年   8篇
  2008年   15篇
  2007年   23篇
  2006年   13篇
  2005年   9篇
  2004年   8篇
  2003年   6篇
  2002年   10篇
  2001年   8篇
  2000年   11篇
  1998年   6篇
  1997年   10篇
  1996年   4篇
  1995年   2篇
  1994年   5篇
  1993年   12篇
  1992年   5篇
  1991年   8篇
  1990年   6篇
  1989年   6篇
  1988年   8篇
  1987年   3篇
  1986年   4篇
  1985年   3篇
  1984年   3篇
  1983年   3篇
  1981年   2篇
  1980年   5篇
  1979年   2篇
  1978年   2篇
  1977年   3篇
  1976年   2篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1970年   1篇
排序方式: 共有420条查询结果,搜索用时 0 毫秒
21.
22.
23.
Two hundred and seventy-five college undergraduates coming from families of 2–7 children completed questionnaires about their relationships with their siblings. Aspects of intersibling communication, influence, and current and past affective relationships were investigated. The relationships reported were generally more positive than those revealed in other investigations of younger children. Presence of two parents in the home, size of the sibling group, and ordinal position of the respondent student had particular effects upon reported relationships. Furthermore, there were qualitative differences in the relationships between sibling pairs of different ordinal statuses. Results indicate that relationships between siblings have both complementary and reciprocal features, and caution against unidimensional characterizations.Teaches courses in child and adolescent development and assessment, and supervises school psychology trainees doing their internships. Received Ph.D. in psychology State University of New York at Albany. Main areas of research are sibling relationships, task attitudes and intrinsic motivation, and topics in adolescence.  相似文献   
24.
25.
26.

Introduction

Longitudinal Analysis: An Introduction to the Special Issue  相似文献   
27.
Two of the three large countries on the North American continent—the United States and Canada—share a number of similarities that often make it difficult for the untrained observer to differentiate between the two nations. On the surface, the two are structured similarly as federal systems that, by definition, exhibit shared power between the national government and provincial or state political entities.Although there are other important social and economic characteristics of the two countries that help explain differences in policy processes and outcomes, it is the contention of this article that one gets the clearest sense of what Elazar has called thinking federal by utilizing an analytical approach that joins questions related to federalism with some conceptual frameworks of the public policy field. Two frameworks undergird the argument in this article—the Lowi typology of different types of policies and Deil Wright's typology of different models that describe the American inter-governmental system.In both countries, policies must be sensitive to the greater interdependencies between units of government as well as to linkages between policy areas. The mechanisms or instrumentalities for dealing with policy issues are intrinsically complex. It is also clear that the intergovernmental networks that exist in both the U.S. and Canada are composed of an array of actors. The differing political structures of the systems do impact the types of intergovernmental policies that have emerged in the two countries. The executive dominance so imbedded in Canadian governments has contributed to their ability to adopt and implement certain controversial redistributive policies, such as a national health insurance program. By contrast, the fragmentation of the U.S. system makes redistributive policies more difficult.  相似文献   
28.
Efficient capillary electrophoretic STR analysis requires rapid, reproducible and robust separation of DNA fragments with reasonable capillary longevity--this is currently accomplished using proprietary commercial polymeric sieving matrices specifically developed for this separation. These matrices, while effective, are costly and do not provide adequate resolution of STR DNA fragments in capillaries with shorter effective separation lengths, increasing the time required to accomplish the separation and minimizing the potential extrapolation to other miniaturized platforms. As the forensic community looks toward next generation microchip technology as a means of processing casework more rapidly, new sieving polymers need to be evaluated for utilization in this platform. The research presented here describes the assessment of commercially-available polymeric sieving matrices for STR analysis, with consideration given to feasibility of incorporation into a microdevice. Polymer composition, molecular weight, and concentration were evaluated, along with an assessment of the effects of buffer composition, separation temperature, and capillary length. These variables were evaluated individually or collectively on the ability to resolve STR DNA fragments and the reproducibility of the separations and the results compared to a proprietary commercial product. A 600,000 Da MW poly(ethylene oxide) (PEO) solution at a 3% (w/v) concentration was determined to be the most suitable matrix for these separations. This polymer, in coated capillaries, provided highly robust and reproducible separations, with near baseline resolution of fragments having single base differences. Reductions in the temperature of the separation, from 60 degrees C to 40 degrees C, and the urea concentration of the buffer, from 7 M to 3.5 M, provided increased longevity of the PEO polymer for repeated separations. Comparison of this polymer with currently specified commercial products used for STR analysis showed that the optimized PEO matrix provided superior separations under all conditions tested. In addition, PEO could be utilized in shorter capillary systems, with a concurrent decrease in analysis time, highlighting its potential for use in shortened capillary or microdevice systems.  相似文献   
29.
Allele frequencies for the 13 STR core loci (D3S1358, VWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, CSF1PO, TPOX, THO1 and D16S539) included in the AmpFlSTR((R)) Profiler Plus and AmpFlSTR((R)) Cofiler kits were obtained for a sample of 700-800 genetically unrelated Brazilians. The expected performance of these loci for personal identification and paternity testing in the Brazilian population was estimated.  相似文献   
30.
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