首页 | 官方网站   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   525736篇
  免费   7170篇
  国内免费   1473篇
工业技术   534379篇
  2022年   3180篇
  2021年   4932篇
  2020年   3496篇
  2019年   4571篇
  2018年   7824篇
  2017年   7634篇
  2016年   7959篇
  2015年   5571篇
  2014年   9262篇
  2013年   24101篇
  2012年   14648篇
  2011年   20180篇
  2010年   15833篇
  2009年   17719篇
  2008年   18107篇
  2007年   17798篇
  2006年   15520篇
  2005年   14219篇
  2004年   13610篇
  2003年   13411篇
  2002年   12636篇
  2001年   12833篇
  2000年   11879篇
  1999年   12607篇
  1998年   32815篇
  1997年   22897篇
  1996年   17450篇
  1995年   13035篇
  1994年   11284篇
  1993年   10972篇
  1992年   7915篇
  1991年   7417篇
  1990年   7261篇
  1989年   7013篇
  1988年   6468篇
  1987年   5766篇
  1986年   5655篇
  1985年   6267篇
  1984年   5900篇
  1983年   5170篇
  1982年   4900篇
  1981年   4966篇
  1980年   4705篇
  1979年   4609篇
  1978年   4408篇
  1977年   5334篇
  1976年   6971篇
  1975年   3796篇
  1974年   3550篇
  1973年   3665篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Design and operation modes of double-junction monolithic lattice-matched solar cells based on the ZnSiP2/Si system of materials have been calculated. The effect of the photoactive region thickness and minority carrier lifetime in ZnSiP2 layers on the efficiency of conversion of the incident solar light energy into electrical power was determined. It is shown that solar cells based on ZnSiP2/Si heterostructures can provide efficiencies of 28.8% at AM1.5D, 100 mW/cm2, and 33.3% at AM1.5D, 200 W/cm2.  相似文献   
72.
The dynamic interaction between the mechanical and electrical drive parameters when damage suddenly appears in the mechanical part of a conveyer belt is investigated. The possibility of using the change in the motor’s electrical parameters as a diagnostic signal is assessed. A model for investigating the dynamic processes in the system consisting of the grid, the induction motor, and the conveyer belt is proposed. The grid and induction motor are described by a model of fourth-order state space, whose output is the torque at the motor shaft. The moments of inertia and pliability of the links between the elements in the mechanical part of the conveyer belt are determined. By gradually identifying the elements with the minimum moment of inertia and distributing their moments of inertia and pliabilities among the adjacent elements, we obtain a three-mass system simulating the mechanical part of the conveyer belt. This dynamic model is solved by means of Matlab Simulink software. The energy characteristics of the drive are determined in dynamic processes following a mechanical accident.  相似文献   
73.
74.
75.
76.
Class I hydrophobin Vmh2, a peculiar surface active and versatile fungal protein, is known to self‐assemble into chemically stable amphiphilic films, to be able to change wettability of surfaces, and to strongly adsorb other proteins. Herein, a fast, highly homogeneous and efficient glass functionalization by spontaneous self‐assembling of Vmh2 at liquid–solid interfaces is achieved (in 2 min). The Vmh2‐coated glass slides are proven to immobilize not only proteins but also nanomaterials such as graphene oxide (GO) and quantum dots (QDs). As models, bovine serum albumin labeled with Alexa 555 fluorophore, anti‐immunoglobulin G antibodies, and cadmium telluride QDs are patterned in a microarray fashion in order to demonstrate functionality, reproducibility, and versatility of the proposed substrate. Additionally, a GO layer is effectively and homogeneously self‐assembled onto the studied functionalized surface. This approach offers a quick and simple alternative to immobilize nanomaterials and proteins, which is appealing for new bioanalytical and nanobioenabled applications.  相似文献   
77.
78.
79.
80.
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-23

京公网安备 11010802026262号