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   8497篇
  免费   357篇
  国内免费   10篇
电工技术   89篇
综合类   5篇
化学工业   1701篇
金属工艺   296篇
机械仪表   152篇
建筑科学   337篇
矿业工程   34篇
能源动力   226篇
轻工业   613篇
水利工程   107篇
石油天然气   49篇
武器工业   1篇
无线电   641篇
一般工业技术   1328篇
冶金工业   1960篇
原子能技术   61篇
自动化技术   1264篇
  2023年   51篇
  2022年   80篇
  2021年   151篇
  2020年   112篇
  2019年   129篇
  2018年   142篇
  2017年   140篇
  2016年   188篇
  2015年   175篇
  2014年   230篇
  2013年   483篇
  2012年   389篇
  2011年   521篇
  2010年   371篇
  2009年   405篇
  2008年   458篇
  2007年   436篇
  2006年   341篇
  2005年   289篇
  2004年   287篇
  2003年   264篇
  2002年   223篇
  2001年   168篇
  2000年   159篇
  1999年   161篇
  1998年   194篇
  1997年   160篇
  1996年   159篇
  1995年   137篇
  1994年   130篇
  1993年   150篇
  1992年   106篇
  1991年   84篇
  1990年   110篇
  1989年   108篇
  1988年   101篇
  1987年   93篇
  1986年   78篇
  1985年   91篇
  1984年   98篇
  1983年   77篇
  1982年   70篇
  1981年   77篇
  1980年   65篇
  1979年   63篇
  1978年   68篇
  1977年   44篇
  1976年   53篇
  1975年   43篇
  1974年   36篇
排序方式: 共有8864条查询结果,搜索用时 0 毫秒
1.
2.
Using an integrated process of data and modeling in HRA   总被引:1,自引:0,他引:1  
The paper describes an approach taken to estimate the probabilities of failure associated with various railroad tasks to prevent accidents (principally collisions and derailments). These probabilities were estimated using an expert elicitation process that used partially relevant data available from a variety of databases and that were filtered and scaled to make them more directly relevant to the analyses being performed. Extensive qualitative studies were performed prior to the elicitation process to identify relevant contexts under which the tasks can be performed.  相似文献   
3.
4.
5.
This study, which is based on responses from over 300 individuals in England and Wales, explores how a willingness to use a water-recycling system of specific configuration varies against a number of factors which are linked to system design, system scale, system context, and water-conservation behaviour. Findings show that there is broad willingness to accept in-house water recycling provided that public health is not compromised.  相似文献   
6.
7.
Interest in medical savings accounts (MSAs) as a potential tool to reduce healthcare costs has been widespread. A small number of countries have either implemented or run pilot programs of MSAs, and vigorous policy debates have taken place in several other countries about the potential merits of introducing MSAs as a method of paying for health care. In this paper we develop a model to assess the cost saving potential of MSAs in a publicly funded healthcare system. We assume that the public healthcare payer may choose between reimbursing healthcare expenditures through an MSA or through a form of third‐party payer insurance. We use the model to identify the conditions under which MSAs may reduce costs. We illustrate using data on healthcare expenditures from Canada.  相似文献   
8.
A deterministic approach for downscaling ~ 40 km resolution Soil Moisture and Ocean Salinity (SMOS) observations is developed from 1 km resolution MODerate resolution Imaging Spectroradiometer (MODIS) data. To account for the lower soil moisture sensitivity of MODIS surface temperature compared to that of L-band brightness temperature, the disaggregation scale is fixed to 10 times the spatial resolution of MODIS thermal data (10 km). Four different analytic downscaling relationships are derived from MODIS and physically-based model predictions of soil evaporative efficiency. The four downscaling algorithms differ with regards to i) the assumed relationship (linear or nonlinear) between soil evaporative efficiency and near-surface soil moisture, and ii) the scale at which soil parameters are available (40 km or 10 km). The 1 km resolution airborne L-band brightness temperature from the National Airborne Field Experiment 2006 (NAFE'06) are used to generate a time series of eleven clear sky 40 km by 60 km near-surface soil moisture observations to represent SMOS pixels across the three-week experiment. The overall root mean square difference between downscaled and observed soil moisture varies between 1.4% v/v and 1.8% v/v depending on the downscaling algorithm used, with soil moisture values ranging from 0 to 15% v/v. The accuracy and robustness of the downscaling algorithms are discussed in terms of their assumptions and applicability to SMOS.  相似文献   
9.
The role of implicit theories in behavioral judgments continues to be a source of debate. In a study exploring the factorial validity of student ratings of instruction, Cadwell and Jenkins (1985) suggested that students' implicit theories of instructor behavior may account for the robust factor structure underlying student ratings. They argued that students rely on the semantic similarity of the rating items, inflating the observed relations among the items. Marsh and Groves cite methodological and conceptual difficulties with the Cadwell and Jenkins study, but most of these difficulties may arise from Marsh and Groves's misconceptions about the role of implicit theories and semantic similarities and, more generally, the cognitive processes underlying judgment tasks. I review these issues and address various points of Marsh and Groves's critique. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
10.
A model has been proposed to explain the failure of the original BMS10-39 epoxy paint on upper vertical surfaces in B-52 fuel tanks. The model involves interaction of the paint with DIEGME, a fuel system ice inhibitor (FSII) in jet fuel, that is distilled from the liquid fuel. In this communication, distillation experiments used to support the model are refined to better match the mass transfer of vapor from fuel in a B-52 fuel tank at close to room temperature. The interaction of these lower temperature distillates with the paint affirms the earlier model. On the basis of these experiments it is proposed that paint failure may be controlled or eliminated by reducing the level of DIEGME in the fuel. Proposed changes in military jet fuel composition are detailed.  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