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   173篇
  免费   10篇
电工技术   1篇
化学工业   53篇
金属工艺   3篇
机械仪表   6篇
建筑科学   6篇
能源动力   3篇
轻工业   21篇
无线电   4篇
一般工业技术   29篇
冶金工业   18篇
原子能技术   2篇
自动化技术   37篇
  2022年   7篇
  2021年   6篇
  2020年   3篇
  2019年   4篇
  2018年   3篇
  2017年   4篇
  2016年   5篇
  2015年   7篇
  2014年   5篇
  2013年   21篇
  2012年   2篇
  2011年   17篇
  2010年   10篇
  2009年   9篇
  2008年   8篇
  2007年   7篇
  2006年   7篇
  2005年   6篇
  2004年   4篇
  2003年   5篇
  2002年   2篇
  2001年   1篇
  2000年   2篇
  1999年   1篇
  1998年   3篇
  1997年   2篇
  1996年   2篇
  1995年   1篇
  1994年   1篇
  1993年   6篇
  1992年   4篇
  1991年   4篇
  1990年   3篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1982年   1篇
  1980年   1篇
  1977年   1篇
  1975年   1篇
  1969年   1篇
  1964年   1篇
排序方式: 共有183条查询结果,搜索用时 15 毫秒
11.
The antenna temperature measured by a microwave radiometer is converted in brightness temperature (TB) by removing the different contributions that do not come from the main lobe of the antenna. Among them, the Earth contribution in the sidelobes may be significant as for the Environmental Satellite mission due to the antenna position on the platform. In such a case, simple corrections commonly applied on previous altimetry missions are inadequate, and a more accurate correction should be determined. We propose in this paper a new method based on global seasonal tables of contamination. This allows application of an accurate sidelobe correction in space and time in the retrieved TB computation  相似文献   
12.
Abstract

In the October 1897 issue of his newly-founded journal, Camera Notes, Alfred Stieglitz began to publish a remarkable series of ‘Nubian’ portraits. They were by F. Holland Day, the Boston photographer whose innovative and dramatic images of young women had already established his reputation internationally. Greatly admired by Stieglitz, Day's ‘Nubian’ series was afforded the most painstaking attention, and reproduced in the expensive process of photogravure.  相似文献   
13.
14.
15.
16.
It is important to understand the extent to which project involvement affects mental health. As projects and project management expand beyond traditional fields, it is also important to compare project involvement and mental health across settings that vary in terms of management structure. This study is the first to validate a Project Involvement Index (PII) useful in various settings to understand how workload relates to mental health defined as high psychological well-being and low psychological distress. Our results demonstrate that the PII is parsimonious measure showing reliability, predictive validity, and discriminant validity. Furthermore, results show that people involved in projects from a non-projectized organization show less mental health than those from a projectized organization.  相似文献   
17.
18.
Near infrared calibrations have been derived and used routinely for a year in the measurement of fat and moisture in air-dried bread. First and second derivative calibrations were obtained using a Pacific Scientific mark II scanning spectrophotometer on samples sent from all over South Africa to the Wheat Board for analysis. Prediction analysis performed on further bread samples gave standard errors of prediction (s.e.p.) of 0.12% fat and 0.13% moisture.  相似文献   
19.
Persistent organic pollutants (POPs) impact upon human and animal health and the wider environment. It is important to determine where POPs are found and the spatial pattern of POP variation. The concentrations of 90 molecules which are members of four families of POPs and two families of herbicides were measured within a region of Northern France as part of the French National Soil Monitoring Network (RMQS: Réseau de Mesures de la Qualité des Sols). We also gather information on five covariates (elevation, soil organic carbon content, road density, land cover and population density) which might influence POP concentrations. The study region contains 105 RMQS observation sites arranged on a regular square grid with spacing of 16 km. The observations include hot-spots at sites of POP application, smaller concentrations where POPs have been dispersed and observations less than the limit of quantification (LOQ) where the soil has not been impacted by POPs. Fifty nine of the molecules were detected at less than 50 sites and hence the data were unsuitable for spatial analyses. We represent the variation of the remaining 31 molecules by various linear mixed models which can include fixed effects (i.e. linear relationships between the molecule concentrations and covariates) and spatially correlated random effects. The best model for each molecule is selected by the Akaike Information Criterion. For nine of the molecules, spatial correlation is evident and hence they can potentially be mapped. For four of these molecules, the spatial correlation cannot be wholly explained by fixed effects. It appears that these molecules have been transported away from their application sites and are now dispersed across the study region with the largest concentrations found in a heavily populated depression. More complicated statistical models and sampling designs are required to explain the distribution of the less dispersed molecules.  相似文献   
20.
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