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   274篇
  免费   5篇
  国内免费   3篇
管理学   24篇
人口学   1篇
丛书文集   12篇
理论方法论   5篇
综合类   216篇
社会学   5篇
统计学   19篇
  2023年   2篇
  2022年   2篇
  2021年   6篇
  2020年   5篇
  2019年   5篇
  2018年   4篇
  2017年   3篇
  2016年   5篇
  2015年   3篇
  2014年   12篇
  2013年   14篇
  2012年   15篇
  2011年   17篇
  2010年   12篇
  2009年   8篇
  2008年   13篇
  2007年   24篇
  2006年   23篇
  2005年   6篇
  2004年   8篇
  2003年   11篇
  2002年   6篇
  2001年   11篇
  2000年   14篇
  1999年   8篇
  1998年   9篇
  1997年   6篇
  1996年   5篇
  1995年   3篇
  1994年   2篇
  1993年   6篇
  1992年   6篇
  1991年   2篇
  1990年   2篇
  1989年   2篇
  1984年   2篇
排序方式: 共有282条查询结果,搜索用时 15 毫秒
11.
Stereology typically concerns estimation of properties of a geometric structure from plane section information. This paperprovides a brief review of some statistical aspects of this rapidly developing field, with some reference to applications in the earth sciences. After an introductory discussion of the scope of stereology, section 2 briefly mentions results applicable when no assumptions can be made about the stochastic nature of the sampled matrix, statistical considerations then arising solelyfrom the ‘randomness’ of the plane section. The next two sections postulate embedded particles of specific shapes, the particular case of spheres being discussed in some detail.

References are made to results for ‘thin slices’ and other prob-ing mechanisms. Randomly located convex particles, of otherwise arbitrary shape, are discussed in section 5 and the review concludes with a specific application of stereological ideas to some data on neolithic mining.  相似文献   
12.
RTI International created a geospatial grid-based sampling methodology that: achieved a probability-based household sample and unbiased estimates; was comparable across countries; used simple frame data available from the in-country census; and was efficient with minimal training to local field staff. The methodology used 1 km2 LandScan world population data, which was further subdivided to smaller grid cells ranging from 50 to 150 m2. To guide fieldwork, georeferenced maps were generated and viewed without an Internet connection using a third-party app and the tablet’s internal global positioning systems receiver. The field staff’s location was displayed in real time as a blue dot enabling field staff to determine household inclusivity. This methodology was successfully implemented for household surveys Latin America, Africa, and Asia. The design is transferable, adaptable, scalable, and can be used anywhere in the world.  相似文献   
13.
Trust in risk information about food related-hazards may be an important determinant of public reactions to risk information. One of the central questions addressed by the risk communication literature is why some individuals and organizations are trusted as sources of risk information and others are not. Industry and government often lack public trust, whereas other sources (for example, consumer organizations, the quality media, medical doctors) are highly trusted. Problematically, previous surveys and questionnaire studies have utilized questions generated by the investigators themselves to assess public perceptions of trust in different sources. Furthermore, no account of the hazard domain was made. In the first study reported here, semistructured interviewing was used to elicit underpinning constructs determining trust and distrust in different sources providing food-related risk information ( n = 35). In the second study, the repertory grid method was used to elicit the terminology that respondents use to distinguish between different potential food-related information sources ( n = 35), the data being submitted to generalised Procrustes analysis. The results of the two studies were combined and validated in survey research ( n = 888) where factor analysis indicated that knowledge in itself does not lead to trust, but that trusted sources are seen to be characterised by multiple positive attributes. Contrary to previous research, complete freedom does not lead to trust—rather sources which possess moderate accountability are seen to be the most trusted.  相似文献   
14.
Let G = (V,E) be a plane graph with nonnegative edge weights, and let be a family of k vertex sets , called nets. Then a noncrossing Steiner forest for in G is a set of k trees in G such that each tree connects all vertices, called terminals, in net N i, any two trees in do not cross each other, and the sum of edge weights of all trees is minimum. In this paper we give an algorithm to find a noncrossing Steiner forest in a plane graph G for the case where all terminals in nets lie on any two of the face boundaries of G. The algorithm takes time if G has n vertices and each net contains a bounded number of terminals.  相似文献   
15.
In this paper, we propose the incremental group testing model for the gap closing problem, which assumes that we can tell the difference between the outcome of testing a subset S, and the outcome of testing S {x}. We also give improvements over currently best results in literature for some other models.  相似文献   
16.
对结构助词“的”的使用规律。从句子、语义、语用三个平面加以考察。“的”的取舍对句法、语义结构关系产生影响时,必须用“的”;对句法、语义结构的改变没有影响时,“的”的取舍由语用上的需要决定。“的”的取舍在句法、语义规则上具有强制性,在语用规则上具有选择性。  相似文献   
17.
改进了文献~([1])所提出的确定主应力方法的结论,使之更完善,应用更方便。  相似文献   
18.
通过对艺术设计教育发展趋势的探讨分析,以及现代科技对艺术设计教育的推动作用的调查研究,论述了艺术设计教育与现代科学技术的融合的重要意义,对推动艺术设计教育与现代科学技术的融合起到一定的促进作用。  相似文献   
19.
该文简述了光子晶体的基本概念及基于平面波方法的理论分析。光子晶体是周期性介质结构,其带隙结构计算复杂,难于进行解析分析,只能使用数值模拟,所以关于光子晶体带隙的计算成为其理论研究的一个重要分支。该文在推导出一维光子晶体的解析解后,使用平面波方法在MATLAB下编写了通用的二维光子晶体能带结构计算程序,找到了出现最大带隙的结构参数,为设计和制作二维光子晶体提供了理论依据。  相似文献   
20.
应用偏微分数值网络生成技术,提出了水泵叶轮设计的新方法,该方法可以准确地确定轴面流道和流线,较好地解决了水泵计算机辅助设计中的一个关键问题。  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