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   4852809篇
  免费   317641篇
  国内免费   184851篇
电工技术   260491篇
技术理论   126篇
综合类   264630篇
化学工业   710626篇
金属工艺   231852篇
机械仪表   258991篇
建筑科学   270977篇
矿业工程   113606篇
能源动力   135831篇
轻工业   403011篇
水利工程   100513篇
石油天然气   143869篇
武器工业   35664篇
无线电   518984篇
一般工业技术   591556篇
冶金工业   571077篇
原子能技术   63964篇
自动化技术   679533篇
  2024年   14710篇
  2023年   45861篇
  2022年   107713篇
  2021年   146867篇
  2020年   107438篇
  2019年   87373篇
  2018年   104508篇
  2017年   116494篇
  2016年   107067篇
  2015年   128462篇
  2014年   174631篇
  2013年   274611篇
  2012年   281865篇
  2011年   320451篇
  2010年   287186篇
  2009年   287595篇
  2008年   294048篇
  2007年   285272篇
  2006年   258986篇
  2005年   216189篇
  2004年   154198篇
  2003年   118656篇
  2002年   111341篇
  2001年   102007篇
  2000年   99223篇
  1999年   81869篇
  1998年   143238篇
  1997年   101168篇
  1996年   85735篇
  1995年   67182篇
  1994年   58458篇
  1993年   50180篇
  1992年   33481篇
  1991年   30252篇
  1990年   30002篇
  1989年   29057篇
  1988年   26939篇
  1987年   24547篇
  1986年   23847篇
  1985年   25580篇
  1984年   22186篇
  1983年   20384篇
  1982年   19208篇
  1981年   19541篇
  1980年   18802篇
  1979年   16825篇
  1978年   16239篇
  1977年   22922篇
  1976年   33663篇
  1975年   14039篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
31.

Accurate prediction of the liquefaction-induced settlement (\({S}_{\mathrm{lc}}\)) is an essential requirement for a good design of buildings resting on liquefiable ground and subjected to seismic shake. However, prediction of the \({S}_{\mathrm{lc}}\) is not straightforward process and it requires advanced soil models and calibrated soil parameters that are not readily available for designers/practitioners. In addition, the available empirical models to estimate the \({S}_{\mathrm{lc}}\) have been developed using either classical regression analysis or multivariate adaptive regression splines and such techniques produce complicated models. Also, these empirical models have been developed utilizing results of numerical modelling. To overcome these limitations, novel model has been developed in this paper utilizing robust regression analysis driven by artificial intelligence called the evolutionary polynomial regression analysis. The new model has been developed using centrifuge results (real laboratory measurements) and can be easily used to accurately estimate the liquefaction induced settlement. The developed model scored a mean absolute error, root mean square error, mean, standard deviation of the predicted to measured values, coefficient of determination, \(a20 - \mathrm{index}\), and EPR coefficient of determination of 2.12 cm, 2.84 cm, 1.06, 0.19, 0.98, 0.77, and 97%, respectively, for the learning data and 1.73 cm, 3.31 cm, 0.99, 0.17, 0.97, 0.75, and 97%, respectively, for the examination data. The developed model has also been used in a parametric study to provide an insight into the sensitivity of the \({S}_{\mathrm{lc}}\) to the foundation width, building height, pressure applied on the foundation, thickness and relative density of the liquefiable layer, and earthquake intensity. The results obtained from the parametric study are reasonable and in agreement with previous studies in the literature. Thus, the developed model can be employed to optimize designs and to reduce design costs as it does not require complicated analyses and/or expensive computational facilities.

  相似文献   
32.
33.
34.
35.
Amphotericin B (AMB) was often used in intra-articular injection administration for fungal arthritis, because it could often bring a satisfactory therapeutic efficacy and a minimum systemic toxic side effect. However, because of the multiple operations and the frequent injections, the compliance of the patients was bad. Therefore, to develop a long-term sustained-released preparation of AMB for mycotic arthritis intra-articular administration is of great significance. The purpose of present study was to develop a long-term sustained-released in situ gel of a water-insoluble drug AMB for mycotic arthritis intra-articular administration. Based on the evaluations of the in vitro properties of the formulations, the formulation containing 10% (w/w) ethanol, 15% (w/w) PG, 0.75% (w/w) HA, 5% (w/w) purified soybean oil, 0.03% (w/w) α-tocopherol, 15% (w/w) water and 55% (w/w) glyceryl monooleate was selected as a suitable intra-articular injectable in situ gel drug delivery system for water-insoluble drug AMB. Furthermore, the results of the in vivo study on rabbits showed that the selected formulation was a safe and effective long-term sustained-released intra-articular injectable AMB preparation. Therefore, the presented in situ AMB gel could reduce the frequency of the administration in the AMB treatment of fungal arthritis, and then would get a good patient compliance.  相似文献   
36.
37.
38.
39.
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