全文获取类型
收费全文 | 87854篇 |
免费 | 8340篇 |
国内免费 | 4826篇 |
专业分类
电工技术 | 6135篇 |
技术理论 | 1篇 |
综合类 | 6492篇 |
化学工业 | 13634篇 |
金属工艺 | 5361篇 |
机械仪表 | 6052篇 |
建筑科学 | 7019篇 |
矿业工程 | 2928篇 |
能源动力 | 2349篇 |
轻工业 | 5823篇 |
水利工程 | 1817篇 |
石油天然气 | 4415篇 |
武器工业 | 871篇 |
无线电 | 10601篇 |
一般工业技术 | 9825篇 |
冶金工业 | 3831篇 |
原子能技术 | 1042篇 |
自动化技术 | 12824篇 |
出版年
2024年 | 389篇 |
2023年 | 1235篇 |
2022年 | 2661篇 |
2021年 | 3596篇 |
2020年 | 2700篇 |
2019年 | 2209篇 |
2018年 | 2457篇 |
2017年 | 2796篇 |
2016年 | 2577篇 |
2015年 | 3856篇 |
2014年 | 4626篇 |
2013年 | 5538篇 |
2012年 | 6292篇 |
2011年 | 6738篇 |
2010年 | 6208篇 |
2009年 | 6150篇 |
2008年 | 5885篇 |
2007年 | 5672篇 |
2006年 | 5194篇 |
2005年 | 4434篇 |
2004年 | 3000篇 |
2003年 | 2509篇 |
2002年 | 2351篇 |
2001年 | 2063篇 |
2000年 | 1742篇 |
1999年 | 1679篇 |
1998年 | 1187篇 |
1997年 | 1037篇 |
1996年 | 895篇 |
1995年 | 727篇 |
1994年 | 599篇 |
1993年 | 430篇 |
1992年 | 351篇 |
1991年 | 275篇 |
1990年 | 215篇 |
1989年 | 191篇 |
1988年 | 146篇 |
1987年 | 97篇 |
1986年 | 79篇 |
1985年 | 37篇 |
1984年 | 38篇 |
1983年 | 17篇 |
1982年 | 24篇 |
1981年 | 15篇 |
1980年 | 22篇 |
1979年 | 12篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 15篇 |
1951年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
步进式加热炉炉温优化设定模型及软件开发 总被引:1,自引:0,他引:1
针对线材厂步进式加热炉实际工况,提出了基于经验规则的炉温优化设定模型和在线自学习获取知识的思想,并以炉温优化设定模型为核心,开发出加热炉计算机控制系统的优化运行软件。 相似文献
72.
Robot Pose Estimation in Unknown Environments by Matching 2D Range Scans 总被引:14,自引:0,他引:14
A mobile robot exploring an unknown environment has no absolute frame of reference for its position, other than features it detects through its sensors. Using distinguishable landmarks is one possible approach, but it requires solving the object recognition problem. In particular, when the robot uses two-dimensional laser range scans for localization, it is difficult to accurately detect and localize landmarks in the environment (such as corners and occlusions) from the range scans.In this paper, we develop two new iterative algorithms to register a range scan to a previous scan so as to compute relative robot positions in an unknown environment, that avoid the above problems. The first algorithm is based on matching data points with tangent directions in two scans and minimizing a distance function in order to solve the displacement between the scans. The second algorithm establishes correspondences between points in the two scans and then solves the point-to-point least-squares problem to compute the relative pose of the two scans. Our methods work in curved environments and can handle partial occlusions by rejecting outliers. 相似文献
73.
74.
含氨烷基聚硅氧烷的研究进展 总被引:1,自引:0,他引:1
对含氨烷基聚硅氧烷的研究进行综述,着重介绍含氨烷基聚硅氧烷的种类,性能特点,制备方法及应用等。 相似文献
75.
76.
利用垂直阵列构作了一类Cartesian认证码,计算了它们的参数,并且在编码规则按等概率分布选取时,成功的模仿攻击和成功的替换攻击概率也被算出。 相似文献
77.
Mechanical alloying in the Al-Bi alloy system 总被引:1,自引:0,他引:1
Mechanical alloying (MA) was carried out to investigate the MA behaviour of the immiscible Al-10, 30 at % Bi alloys. After the MA processing, the Al and Bi were finely and homogeneously alloyed. The Bi crystallite size decreased to 25 nm and 30 nm in the Al-10 at % Bi and Al-30 at % Bi alloys, respectively. By increasing the MA time, the hardness increased up to a value of 80 H
v, which is larger than that obtained from the rule of mixtures. The lattice parameter of Bi decreased by about 0.27%, which shows the formation of a non-equilibrium hcp Bi super-saturated solid solution. The extended solubility of Al in Bi was 1.9% in the Al-30 at % Bi alloy. Due to the extended solubility, depression of the melting temperature of hcp Bi was confirmed in the mechanically alloyed Al-Bi alloys. The maximum depression in the temperature was about 10 K. The measured values corresponded well with those estimated from the extrapolation of the solidus line. 相似文献
78.
79.
Ha J.H. Kim S.W. Seol Y.S. Park H.K. Choi S.H. 《Semiconductor Manufacturing, IEEE Transactions on》1996,9(2):289-291
The plug loading effect occurring during the etchback of tungsten was investigated in a magnetically enhanced reactive ion etcher using SF 6/Ar mixtures. It was found that while the plug loading effect is independent of varying SF6/Ar flow rate ratio and magnetic field intensity, it is reduced under the condition of high selectivity of tungsten relative to TiN which was achieved at high chamber pressure and low RF power. It is proposed that when TiN is used as a glue layer, the W etch rate enhancement in the plug is mainly controlled by a local loading effect. Under the optimized etchback conditions the plug loss was successfully controlled without the tungsten residue left on severe topology 相似文献
80.
Feng M. Scherrer D. Kruse J. Apostolakis P.J. Middleton J.R. 《Electron Device Letters, IEEE》1995,16(4):139-141
We present experimental evidence that the noise figure (NF) and associated gain equal to those achieved with GaAs pseudomorphic high electron mobility transistors (GaAs p-HEMT's) can also be accomplished by ion implanted GaAs metal-semiconductor field-effect transistors (GaAs MESFET's). These measured noise figure results as a function of low temperature for GaAs MESFET's and p-HEMT's clearly suggest that the transport properties of the two-dimensional electron gas in HEMT's and p-HEMT's do not make a significant contribution to the noise reduction at high frequency operation of these devices 相似文献