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   26413篇
  免费   761篇
  国内免费   103篇
工业技术   27277篇
  2023年   124篇
  2022年   337篇
  2021年   669篇
  2020年   513篇
  2019年   701篇
  2018年   1296篇
  2017年   1346篇
  2016年   1564篇
  2015年   979篇
  2014年   1411篇
  2013年   1860篇
  2012年   1743篇
  2011年   1696篇
  2010年   1524篇
  2009年   1741篇
  2008年   1592篇
  2007年   1440篇
  2006年   1212篇
  2005年   781篇
  2004年   527篇
  2003年   327篇
  2002年   333篇
  2001年   294篇
  2000年   589篇
  1999年   474篇
  1998年   556篇
  1997年   489篇
  1996年   133篇
  1995年   106篇
  1994年   89篇
  1993年   78篇
  1992年   63篇
  1991年   52篇
  1990年   52篇
  1989年   34篇
  1988年   19篇
  1987年   25篇
  1986年   29篇
  1985年   32篇
  1984年   35篇
  1983年   24篇
  1981年   17篇
  1980年   27篇
  1979年   36篇
  1978年   30篇
  1977年   18篇
  1976年   34篇
  1975年   16篇
  1969年   24篇
  1968年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
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   
44.
Food Science and Biotechnology - To determine the physiochemical properties of the 4-α-glucanotransferase from Bifidobacterium sp., the bllj_0114 gene encoding 4-α-glucanotransferase was...  相似文献   
45.
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   
46.
Electrospark treatment of OT4-1 titanium alloy was performed sequentially with a STIM-20N hard-alloy electrode (TiC–20% Ni) and carbon-containing material (graphite and carbon-based composite materials). Kinetics of the mass transfer of the hard-alloy electrode was studied. The cathode mass loss during the first minute of the treatment was established. The kinetics results were processed using the methods of mathematical statistics. The erosion resistance of the applied carbon-containing materials was determined. Phase composition and relief of the coatings formed were analyzed. It was found that the application of the carbon-containing material increases the content of refractory phases in the coatings. Increase in the time of the treatment using the carbon-containing materials decreases the roughness of the coatings.  相似文献   
47.
该文利用色集事先分配法、构造染色法、反证法探讨了完全三部图K4,4,p (p≥1008)的点可区别IE-全染色问题,确定了K4,4,p (p≥1008)的点可区别IE-全染色数。  相似文献   
48.
Technical Physics Letters - The magnetoelectric (ME) effect in a planar amorphous ferromagnet–piezoelectric lead zirconate titanate (PZT) composite structure can be effectively excited by...  相似文献   
49.
50.
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