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   332008篇
  免费   3189篇
  国内免费   975篇
电工技术   5392篇
综合类   2469篇
化学工业   47690篇
金属工艺   19373篇
机械仪表   14063篇
建筑科学   6810篇
矿业工程   3232篇
能源动力   6163篇
轻工业   16622篇
水利工程   4667篇
石油天然气   8960篇
武器工业   22篇
无线电   34450篇
一般工业技术   72969篇
冶金工业   40668篇
原子能技术   7601篇
自动化技术   45021篇
  2021年   2086篇
  2019年   2023篇
  2018年   22194篇
  2017年   21717篇
  2016年   16043篇
  2015年   3158篇
  2014年   4092篇
  2013年   8992篇
  2012年   10159篇
  2011年   21310篇
  2010年   18748篇
  2009年   16352篇
  2008年   17235篇
  2007年   19419篇
  2006年   5749篇
  2005年   8880篇
  2004年   7085篇
  2003年   6840篇
  2002年   5352篇
  2001年   4615篇
  2000年   4447篇
  1999年   4267篇
  1998年   10238篇
  1997年   7212篇
  1996年   5544篇
  1995年   4153篇
  1994年   3635篇
  1993年   3877篇
  1992年   3009篇
  1991年   3041篇
  1990年   2892篇
  1989年   2854篇
  1988年   2875篇
  1987年   2509篇
  1986年   2568篇
  1985年   2857篇
  1984年   2689篇
  1983年   2554篇
  1982年   2302篇
  1981年   2269篇
  1980年   2346篇
  1979年   2359篇
  1978年   2383篇
  1977年   2487篇
  1976年   2876篇
  1975年   2188篇
  1974年   2068篇
  1973年   2166篇
  1972年   1940篇
  1971年   1755篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
962.
963.
964.
965.
We describe the lyotropic liquid crystalline phase transitions in the lipid mixture dipalmitoil-PC/dilauroy-PC/cholesterol by 3D spin-1 lattice model. The formation of nanoscale domains with the characteristic size about 300 nm was studied in experiments on confocal fluorescence microscopy (CFM) (G. V. Feigenson and J. T. Buboltz, Biophys. J. 80, 2775 (2001)). The structure parameters of the lamellar vesicle in dipalmitoil-PC-rich phase, corresponding to these regions, are verified by numerical Monte Carlo simulations on the lattice. We point its superconductivity analogy properties at the region of phase stability for composition-dependent nanoscopic region.  相似文献   
966.
967.
968.
We have investigated the current pulse width dependence on current-driven magnetization reversal in double-barrier structures using GaMnAs-based magnetic tunneling junctions (MTJ) in order to clarify the origin of low threshold current density for current-driven magnetization reversal. Comparing with the case of single-barrier MTJ, the pulse-width dependence reveals that threshold current density is reduced by double-barrier MTJ. We confirmed that the threshold current density in the order of 104 A/cm2 is estimated considering the effect of current pulse width.  相似文献   
969.
Achieving an innovative integrated sensor fusion architecture with a robust vehicle navigation and localization using an extended Kalman filter, interval analysis and covariance intersection that can overcome the uncertainty in the system model and sensor noise statistics. There are various approaches to the problem, but here the focus is on an approach which can guaranteed performance of sensor-based navigation. The guaranteed performance is quantified by explicit bounds of position estimate of a ground vehicle. Ground vehicles generally carry dead reckoning sensors such as wheel encoders and inertial sensors, to measure acceleration and angle rate, while obstacle detection and mapmaking is done with time-of-flight ultrasonic sensors. Most of these sensors give overlapping or complementary information and sometimes are redundant as well, which offers scope for exploiting data fusion. The purpose here is to achieve data fusion for ground vehicles with low-cost sensors by forming an intelligent sensor system. This is accomplished by combining the sensors' measurements and processing these measurements with data fusion algorithms. The algorithms are complementary in the sense that they compensate for each other's limitations, so that the resulting performance of the sensor system is better than its individual components.  相似文献   
970.
A Full Fingerprint Verification System for a Single-Line Sweep Sensor   总被引:1,自引:0,他引:1  
This paper presents a full fingerprint verification system. It is composed of a tactile fingerprint sensor, integrated read out and conversion circuits, and dedicated recognition algorithms. The sensor is a single-line sweep mode sensor, e.g., it is made of a single line of sensing elements, thus covering the minimum surface of silicon. Compared with cm2 sized touch sensors, it offers a large cost reduction and possibility of easy integration into portable devices. The use of a single line to measure a fingerprint requires the user to sweep its finger along the sensor. This sensing scheme produces fingerprint images with several distortions that needs further image processing to allow efficient fingerprint recognition. This is why we developed and present here specific algorithms to take care of the sensor's specifications. This paper will present measurement results, as well as a performance evaluation of the entire verification system.  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