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   168625篇
  免费   12070篇
  国内免费   6198篇
电工技术   8934篇
技术理论   9篇
综合类   8808篇
化学工业   27559篇
金属工艺   10083篇
机械仪表   10174篇
建筑科学   10007篇
矿业工程   3985篇
能源动力   3692篇
轻工业   9432篇
水利工程   3204篇
石油天然气   9642篇
武器工业   1071篇
无线电   17717篇
一般工业技术   26969篇
冶金工业   11146篇
原子能技术   4877篇
自动化技术   19584篇
  2024年   730篇
  2023年   2362篇
  2022年   4731篇
  2021年   6349篇
  2020年   4783篇
  2019年   4104篇
  2018年   5203篇
  2017年   5651篇
  2016年   5202篇
  2015年   5749篇
  2014年   7437篇
  2013年   8999篇
  2012年   9644篇
  2011年   10374篇
  2010年   8822篇
  2009年   8627篇
  2008年   8518篇
  2007年   7978篇
  2006年   7393篇
  2005年   6314篇
  2004年   4824篇
  2003年   4763篇
  2002年   4780篇
  2001年   4350篇
  2000年   3779篇
  1999年   3352篇
  1998年   2650篇
  1997年   2220篇
  1996年   1987篇
  1995年   1747篇
  1994年   1469篇
  1993年   1248篇
  1992年   1222篇
  1991年   1077篇
  1990年   1091篇
  1989年   1013篇
  1988年   896篇
  1987年   842篇
  1986年   763篇
  1985年   715篇
  1984年   701篇
  1981年   668篇
  1979年   736篇
  1978年   777篇
  1977年   739篇
  1976年   755篇
  1975年   713篇
  1974年   719篇
  1973年   723篇
  1972年   705篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
191.
A method of calculating the response of sensitive elements based on wave delay devices is described using as an example a gauge for measuring the diameter of holes in metal objects. The efficiency of a sensitive element consisting a cylindrical helix with a longitudinally conducting shield is demonstrated. Translated from Izmeritel'naya Tekhnika, No. 9, pp. 46–50, September, 1996.  相似文献   
192.
As a science and as a special activity concerned with measurements, the science of metrology pursues a classical, orthodox purpose, mainly involving the measurement of physical quantities. The term “measurement” is now applied also to social, economic, medical, and other disciplines, including cybernetics and problems of management and control. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 17–20, July, 1996.  相似文献   
193.
194.
A torque sensorless control for a multi-degree-of-freedom manipulator is described. In the method, two disturbance observers are applied to each joint. One is used to realize a robust motion controller. The other is used to obtain a sensorless torque controller. A robust acceleration controller based on the disturbance observer is shown. To obtain the sensorless torque control, it is necessary to calculate the reaction torque when the mechanical system performs a force task. The calculation method for the reaction torque is explained. Then the method is expanded to workspace force control in the multi-degree-of-freedom manipulator. Several experimental results are shown to confirm the validity of the proposed sensorless force controller  相似文献   
195.
To investigate the prognostic factors of primary liver cancer (PLC) and improve the long-term results, 1,248 cases of PLC were analysed. Univariate analysis demonstrated that discovery approach, staging of PLC, original gamma-GPT, resection, radical resection, original AFP, tumor size, tumor number, and tumor capsule have very significant effects on prognosis of PLC (all P < 0.001); cirrhosis, HBsAg, local resection, and tumor embolus in portal vein were also significant difference (all P < 0.05); age, sex, original AFP, hepatitis, and differentiation of PLC cells were no significant difference (all P > 0.05). Multivariate analysis demonstrated that original gamma-GPT, radical resection, tumor size, and tumor number were the most significant prognostic factors (all P < 0.001). Some aspects improving long-term survival were discussed.  相似文献   
196.
Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 12, pp. 20–23, December, 1993.  相似文献   
197.
The main notions and facts of the geometrical decomposition theory were characterized in brief. The E.S. Pyatnitskii principle of decomposition was treated as the solution of the problem of assignment of feedback controls so that the controlled system admits a decomposition suitable for realization of the control objectives. It was hypothesized that this method of control is advisable if the complexity of the controlled system exceeds a certain limit.  相似文献   
198.
199.
A chamber for X-ray diffractometry of gas-hydrate samples designed for operation at pressures of up to 700 atm and low temperatures is described. The leakproof character of the chamber at temperatures down to ?150°C is ensured by an Amaga-type seal with a fluoroplastic gasket pressed by disk springs. The chamber was used to study double hydrates using a synchrotron radiation source and a pressure generator based on a thermal multiplier.  相似文献   
200.
利用平板型热管纺丝装置对普通高速纺丝机进行技术改造,并一步法生产出充分结晶的PET纤维(FCY)。该纤维可直接用于织造,调节热管温度、热管安装位置可获得满足后道工序不同需要的FCY。  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