全文获取类型
收费全文 | 35509篇 |
免费 | 2656篇 |
国内免费 | 1231篇 |
专业分类
电工技术 | 1719篇 |
技术理论 | 4篇 |
综合类 | 2204篇 |
化学工业 | 6134篇 |
金属工艺 | 1742篇 |
机械仪表 | 2158篇 |
建筑科学 | 3051篇 |
矿业工程 | 870篇 |
能源动力 | 993篇 |
轻工业 | 2294篇 |
水利工程 | 574篇 |
石油天然气 | 1978篇 |
武器工业 | 226篇 |
无线电 | 3940篇 |
一般工业技术 | 4903篇 |
冶金工业 | 1863篇 |
原子能技术 | 417篇 |
自动化技术 | 4326篇 |
出版年
2024年 | 130篇 |
2023年 | 509篇 |
2022年 | 842篇 |
2021年 | 1196篇 |
2020年 | 948篇 |
2019年 | 798篇 |
2018年 | 854篇 |
2017年 | 1064篇 |
2016年 | 927篇 |
2015年 | 1252篇 |
2014年 | 1518篇 |
2013年 | 2007篇 |
2012年 | 2048篇 |
2011年 | 2177篇 |
2010年 | 1931篇 |
2009年 | 1813篇 |
2008年 | 1927篇 |
2007年 | 1783篇 |
2006年 | 1916篇 |
2005年 | 1821篇 |
2004年 | 1151篇 |
2003年 | 1079篇 |
2002年 | 1069篇 |
2001年 | 904篇 |
2000年 | 1079篇 |
1999年 | 1147篇 |
1998年 | 973篇 |
1997年 | 835篇 |
1996年 | 756篇 |
1995年 | 688篇 |
1994年 | 516篇 |
1993年 | 367篇 |
1992年 | 309篇 |
1991年 | 273篇 |
1990年 | 199篇 |
1989年 | 167篇 |
1988年 | 118篇 |
1987年 | 69篇 |
1986年 | 61篇 |
1985年 | 54篇 |
1984年 | 24篇 |
1983年 | 16篇 |
1982年 | 20篇 |
1981年 | 16篇 |
1980年 | 19篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1970年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
A multi-channel continuous toxicity monitoring system developed in our laboratory, based on two-stage mini-bioreactors, was successfully implemented in the form of computer-based data acquisition. The multi-channel system consists of a series of a two-stage minibioreactor systems connected by a fiber optic probe to a luminometer, and uses genetically engineered bioluminescent bacteria for the detection of the potential toxicity from the soluble chemicals. This system can be stably and continuously operated due to the separation of the culture reactor from the test reactor and accomplish easy and long-term monitoring without system shut down by abrupt inflows of severe polluting chemicals. Four different recombinant bioluminescent bacteria were used in different channels so that the modes of the samples toxicities can be reasonably identified and evaluated based upon the response signature of each channel. The bioluminescent signatures were delivered from four channels by switching one at once, while the data is automatically logged to an IBM compatible computer. We also achieved the enhancement of the system through the manipulation of the dilution rate and the use of thermo-lux fusion strains. Finally, this system is now being implemented to a drinking water reservoir and river for remote sensing as an early warning system. 相似文献
12.
Jiang Minhong Gu Zhengfei Cheng Gang 《中国稀土学报(英文版)》2005,23(6):723-723
Polymer matrix RE-Fe giant magnetostrictire composite (GMPC) was prepared using bonding and magnetic field forming technique, and magnetostriction of samples was measured for different compressive stress. The experimental results show thai there is certain compressive effect in GMPC. And the influence of compressive stress on magnetostriction of sample was investigated. It offers essential reference for application and device design of GMPC. 相似文献
13.
Average consensus in networks of dynamic agents with switching topologies and multiple time-varying delays 总被引:5,自引:0,他引:5
In this paper, we discuss average consensus problem in undirected networks of dynamic agents with fixed and switching topologies as well as multiple time-varying communication delays. By employing a linear matrix inequality method, we prove that all the nodes in the network achieve average consensus asymptotically for appropriate communication delays if the network topology is connected. Particularly, several feasible linear matrix inequalities are established to determine the maximal allowable upper bound of time-varying communication delays. Numerical examples are given to demonstrate the effectiveness and the sharpness of the theoretical results. 相似文献
14.
15.
16.
17.
研究了电子束、离子束作用于Al2O3表面时成分的变化,表明无论电子束或离子束都能使Al2O3发生分解,产生导电的元素Al。实验在PHI610·SAM上进行,电子束轰击下(3keV,O.5μA,入射角60°)10s就有元素Al分解出来,2min以后就达到饱和,分解析出量随时间成a(1-e-bt)的关系。离子束轰击下同样发生元素Al的分解,但当Ei>3keV时,由于剥离速率加大,溅射5min时表面Al峰反而比1min时要弱。这时表面Al含量处于分解析出与溅射剥离的动态平衡中。实验还发现了Al2O3的解析与表面成分有关(如碳的含量)。最后讨论电子束与离子束的解析机理。 相似文献
18.
19.
A structured genetic algorithm (SGA) approach is developed for robust controller design based on the concept of an H∞ loop-shaping technique and the method of inequalities. Such an SGA is capable of simultaneously searching the orders and coefficients of the precompensator and postcompensator for the weighted plant. It is, therefore, not necessary to predefine the order of compensators as in usual practice. A multiple objective ranking approach is also incorporated so that the design criteria of extreme plants can be easily achieved. The effectiveness of such a technique is illustrated by a high-purity distillation column design example 相似文献
20.