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   482908篇
  免费   6106篇
  国内免费   1176篇
电工技术   8526篇
综合类   423篇
化学工业   76849篇
金属工艺   19332篇
机械仪表   14491篇
建筑科学   11560篇
矿业工程   2938篇
能源动力   11013篇
轻工业   46005篇
水利工程   5221篇
石油天然气   10761篇
武器工业   44篇
无线电   51389篇
一般工业技术   92823篇
冶金工业   89548篇
原子能技术   11829篇
自动化技术   37438篇
  2021年   3841篇
  2019年   3606篇
  2018年   6453篇
  2017年   6362篇
  2016年   6802篇
  2015年   4329篇
  2014年   7399篇
  2013年   20561篇
  2012年   11828篇
  2011年   16059篇
  2010年   12916篇
  2009年   14587篇
  2008年   15142篇
  2007年   15104篇
  2006年   13378篇
  2005年   12192篇
  2004年   11473篇
  2003年   11064篇
  2002年   11186篇
  2001年   10913篇
  2000年   10553篇
  1999年   10518篇
  1998年   25137篇
  1997年   18361篇
  1996年   14265篇
  1995年   10871篇
  1994年   9857篇
  1993年   9595篇
  1992年   7486篇
  1991年   7172篇
  1990年   7191篇
  1989年   7111篇
  1988年   6928篇
  1987年   5949篇
  1986年   6007篇
  1985年   6938篇
  1984年   6618篇
  1983年   6020篇
  1982年   5645篇
  1981年   5854篇
  1980年   5657篇
  1979年   5486篇
  1978年   5562篇
  1977年   6322篇
  1976年   8137篇
  1975年   5028篇
  1974年   4781篇
  1973年   4915篇
  1972年   4192篇
  1971年   3877篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
1.
Multimedia Tools and Applications - Remote Sensing categorical signature classification has gained significant implications on spatial resolution image analysis due to differences in the...  相似文献   
2.
3.
4.
Theoretical Foundations of Chemical Engineering - On the basis of the classic concepts of the theory of solid-phase combustion, for the first time, a model with a detailed scheme of chemical...  相似文献   
5.
Engineering new glass compositions have experienced a sturdy tendency to move forward from (educated) trial-and-error to data- and simulation-driven strategies. In this work, we developed a computer program that combines data-driven predictive models (in this case, neural networks) with a genetic algorithm to design glass compositions with desired combinations of properties. First, we induced predictive models for the glass transition temperature (Tg) using a dataset of 45,302 compositions with 39 different chemical elements, and for the refractive index (nd) using a dataset of 41,225 compositions with 38 different chemical elements. Then, we searched for relevant glass compositions using a genetic algorithm informed by a design trend of glasses having high nd (1.7 or more) and low Tg (500 °C or less). Two candidate compositions suggested by the combined algorithms were selected and produced in the laboratory. These compositions are significantly different from those in the datasets used to induce the predictive models, showing that the used method is indeed capable of exploration. Both glasses met the constraints of the work, which supports the proposed framework. Therefore, this new tool can be immediately used for accelerating the design of new glasses. These results are a stepping stone in the pathway of machine learning-guided design of novel glasses.  相似文献   
6.
Journal of Chemical Ecology - Biocontrol agents such as parasitic wasps use long-range volatiles and host-associated cues from lower trophic levels to find their hosts. However, this chemical...  相似文献   
7.
This study presents the development and characterization of PVDF-conjugated polymer nanofiber-based systems. Five different conducting polymers (CPs) were synthesized successfully and used to create the nanofiber systems. The CPs used are polyaniline (PANI), polypyrrole (PPY), polyindole (PIN), polyanthranilic acid (PANA), and polycarbazole (PCZ). Nanofiber systems were produced utilizing the Forcespinning® technique. The nanofiber systems were developed by mechanical stretching. No electrical field or post-process poling was used in the nanofiber systems. The morphology, structure, electrochemical and piezoelectric performance was characterized. All of the nanofiber PVDF/CP systems displayed higher piezoelectric performance than the fine fiber PVDF systems. The PVDF/PPY nanofiber system displays the highest piezoelectric performance of 15.56 V. The piezoelectric performance of the PVDF/CP nanofiber systems favors potential for an attractive source of energy where highly flexible membranes could be used in power actuators, sensors and portable, and wireless devices to mention some.  相似文献   
8.
Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid...  相似文献   
9.
Journal of Communications Technology and Electronics - A statistical study of the effectiveness of the non-threshold search procedure for a noise-like phase-shift keyed signal by the delay time is...  相似文献   
10.
Glass and Ceramics - Ceramic bricks based on low-melting clay and ferro-dust from self-disintegrating, low-carbon, ferrochrome slags, graded from M100 to M175, respectively, were obtained in the...  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