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   1649篇
  免费   508篇
各国政治   379篇
工人农民   50篇
世界政治   212篇
外交国际关系   94篇
法律   718篇
中国政治   35篇
政治理论   636篇
综合类   33篇
  2021年   29篇
  2020年   36篇
  2019年   156篇
  2018年   93篇
  2017年   141篇
  2016年   150篇
  2015年   134篇
  2014年   123篇
  2013年   538篇
  2012年   90篇
  2011年   91篇
  2010年   107篇
  2009年   43篇
  2008年   68篇
  2007年   39篇
  2006年   38篇
  2005年   21篇
  2004年   29篇
  2003年   15篇
  2002年   18篇
  2001年   6篇
  2000年   17篇
  1999年   12篇
  1998年   10篇
  1997年   13篇
  1996年   13篇
  1995年   12篇
  1994年   12篇
  1993年   13篇
  1992年   7篇
  1991年   5篇
  1990年   8篇
  1989年   4篇
  1988年   8篇
  1987年   3篇
  1986年   6篇
  1985年   5篇
  1984年   8篇
  1983年   6篇
  1982年   2篇
  1981年   6篇
  1980年   6篇
  1979年   4篇
  1978年   5篇
  1977年   4篇
  1976年   1篇
  1974年   2篇
排序方式: 共有2157条查询结果,搜索用时 15 毫秒
31.
The forensic science community raised the need for improved evidence recognition, collection, and visualization analytical instrumentation for field and laboratory use. While the 3D optical techniques for imaging static objects have been extensively studied, there is still a major gap between current knowledge and collecting high‐quality footwear and tire impression evidence. Among optical means for 3D imaging, digital fringe projection (DFP) techniques reconstruct 3D shape from phase information, achieving camera‐pixel spatial resolution. This paper presents a high‐resolution 3D imaging technology using DFP techniques dedicated to footwear and tire impression capture. We developed fully automated software algorithms and a graphical user interface (GUI) that allow anyone without training to operate for high‐quality 3D data capture. We performed accuracy evaluations and comparisons comparing with the commercial high‐end 3D scanner and carried out qualitative tests for various impressions comparing with the current practices. Overall, our technology achieves similar levels of accuracy and resolution with a high‐end commercially available 3D scanner, while having the merits of being (1) more affordable; (2) much easier to operate; and (3) more robust. Compared with the current practice of casting, our technology demonstrates its superiority because it (1) is non‐destructive; (2) collects more evidence detail than casts, especially when an impression is fragile; (3) requires less time and money to collect each piece of evidence; and (4) results in a digital file that can easily be shared with other examiners.  相似文献   
32.
33.
High‐throughput sequencing (HTS) of large panels of single nucleotide polymorphisms (SNPs) provides an alternative or complimentary approach to short tandem repeats (STRs) panels for the analysis of complex DNA mixture forensic samples. For STRs, methods to estimate individual contribution concentrations compare capillary electrophoresis peak heights, peak areas, or HTS allele read counts within a mixture. This article introduces three approaches (mean, median, and slope methods) for estimating individual DNA contributions to forensic mixtures for HTS/massively parallel sequencing (MPS) SNP panels. For SNPs, the major:minor allele ratios or counts, unique to each contributor, were compared to estimate contributor proportion within the mixture using the mean, median, and slope intercept for these alleles. The estimates for these three methods were typically within 5% of planned experimental contributions for defined mixtures.  相似文献   
34.
35.
36.
37.
Abstract

In an effort to popularise the gas stove, boost sales and minimize the genuine and perceived dangers of using this volatile domestic appliance, late Victorian gas managers and stove manufacturers employed female cookery teachers to perform public demonstrations at trade exhibitions throughout the country. Eventually, these women comprised a special department of gas sales, calling directly on customers in their homes to offer personal instruction in the proper use and care of gas stoves. Part social workers, part salesgirls, the ‘lady demons’, short for lady demonstrators, moved between the traditionally gendered separate spheres of work and home, consciously constructing a professional image that reconciled the social tensions of this new occupation. They offer an early example of women's entrance into the corporate business world, the feminisation of consumption, and the combination of customer service with social welfare.  相似文献   
38.
39.
The end of the Cold War has created new dangers and opportunities. The formation of an Indian Ocean Rim trading bloc has the potential to benefit some of the poorest people in the world. Regional maritime co‐operation could provide the catalyst for alleviating poverty on the Indian Ocean Rim by giving a spurt to incomes and employment from the seas.  相似文献   
40.
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