全文获取类型
收费全文 | 78831篇 |
免费 | 8044篇 |
国内免费 | 4513篇 |
专业分类
电工技术 | 6348篇 |
技术理论 | 2篇 |
综合类 | 6009篇 |
化学工业 | 11626篇 |
金属工艺 | 5037篇 |
机械仪表 | 5505篇 |
建筑科学 | 5520篇 |
矿业工程 | 2199篇 |
能源动力 | 2543篇 |
轻工业 | 5374篇 |
水利工程 | 1901篇 |
石油天然气 | 3422篇 |
武器工业 | 1014篇 |
无线电 | 9800篇 |
一般工业技术 | 8760篇 |
冶金工业 | 3602篇 |
原子能技术 | 994篇 |
自动化技术 | 11732篇 |
出版年
2024年 | 236篇 |
2023年 | 898篇 |
2022年 | 1949篇 |
2021年 | 2888篇 |
2020年 | 2126篇 |
2019年 | 1741篇 |
2018年 | 1955篇 |
2017年 | 2335篇 |
2016年 | 2307篇 |
2015年 | 3154篇 |
2014年 | 4125篇 |
2013年 | 4853篇 |
2012年 | 6111篇 |
2011年 | 6484篇 |
2010年 | 6034篇 |
2009年 | 5848篇 |
2008年 | 5706篇 |
2007年 | 5308篇 |
2006年 | 4908篇 |
2005年 | 4045篇 |
2004年 | 3162篇 |
2003年 | 2915篇 |
2002年 | 3060篇 |
2001年 | 2663篇 |
2000年 | 1657篇 |
1999年 | 1220篇 |
1998年 | 782篇 |
1997年 | 655篇 |
1996年 | 500篇 |
1995年 | 407篇 |
1994年 | 317篇 |
1993年 | 228篇 |
1992年 | 166篇 |
1991年 | 133篇 |
1990年 | 116篇 |
1989年 | 88篇 |
1988年 | 50篇 |
1987年 | 53篇 |
1986年 | 41篇 |
1985年 | 20篇 |
1984年 | 28篇 |
1983年 | 22篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 12篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1975年 | 6篇 |
1959年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
Ki Yong Lee Souhwan Jung 《Electronics letters》1998,34(16):1567-1568
The authors investigate the problem of nonlinear adaptive equalisation in the presence of intersymbol interference, additive white Gaussian noise and co-channel interference. An extended radial basis function (RBF) network is proposed, in which regression weights are used in the output layer and the hidden unit is defined to have the Gaussian formula with the Mahalanobis distance. It is shown by simulation that the proposed structure gives reduced computational complexity without performance degradation, compared to that of the conventional RBF equaliser 相似文献
94.
Boundary element analysis of thermal stress intensity factors for interface griffith and cusp cracks
Kang Yong Lee
Woon Cheon Baik
《Engineering Fracture Mechanics》1994,47(6):909-918The thermal stress intensity factors for interface cracks of Griffith and symmetric lip cusp types under vertical uniform heat flow in a finite body are calculated by the boundary element method. The boundary conditions on the crack surfaces are insulated or fixed to constant temperature. The relationship between the stress intensity factors and the displacements on the nodal point of a crack-tip element is derived. The numerical values of the thermal stress intensity factors for an interface Griffith crack in an infinite body are compared with the previous solutions. The thermal stress intensity factors for a symmetric lip cusp interface crack in a finite body are calculated with respect to various effective crack lengths, configuration parameters, material property ratios and the thermal boundary conditions on the crack surfaces. Under the same outer boundary conditions, there are no appreciable differences in the distribution of thermal stress intensity factors with respect to each material property. However, the effect of crack surface thermal boundary conditions on the thermal stress intensity factors is considerable. 相似文献
95.
96.
Ki Hyun Kim Yong Hoon Kang Byoungho Lee 《Photonics Technology Letters, IEEE》1997,9(12):1610-1612
A photorefractive volume hologram was recorded and probed using light diffracted from a tapered optical fiber as a reference beam. A single-mode fiber (SMF) was chemically etched and tapered to give a complicated beam pattern, and it is shown that the tapered optical fiber can be utilized to increase the storage density of the volume hologram. Spatial selectivity of the volume hologram with this method was increased by two times compared to the normal SMF referencing, which is due to the fact that the complicated beam pattern has little correlation with its shifted version 相似文献
97.
Kyu-Jin Wee Yong-Sup Shin 《Communications Magazine, IEEE》1998,36(9):160-164
In this article Korean development of IMT-2000 is considered. It includes the second-generation digital mobile communications, R&D and standardization activities related to IMT-2000, and the authors' perspectives on IMT-2000 in Korea. In Korea, there are many activities for development of IMT-2000 radio transmission technologies, and the results of these activities will be the submission of technologies to the ITU. However, the Korean telecommunications standardization body (TTA) will make every effort to make a common global standard for IMT-2000. Therefore, the TTA will make a domestic standard for IMT-2000 after the ITU finalizes the related Recommendations. It seems to the authors that difficulties in harmonization in the TTA are very similar to difficulties in harmonization worldwide. The only way of reaching the harmonization of IMT-2000 in Korea is that the key players should have the view from the end users' seat 相似文献
98.
制作压力传感器时,在二氧化硅层上淀积多晶硅膜,既可利用优良的机械特性,又可保证压敏电阻与衬底间具有良好的绝缘性,由此可大大提高器件的温度特性。介绍了一种多晶硅压力传感器的原理和设计。实验结果表明,这类传感器具有灵敏度好,精度高等特点,电路工作范围为0-250℃,且具有良好的温度稳定性。 相似文献
99.
Dong-Guk Shin 《Knowledge and Data Engineering, IEEE Transactions on》1994,6(3):430-443
This paper describes a model that can account for ad hoc user-responses to argument interrogative type of system-initiated questions. Successful implementation of the model can provide an alternative solution that is more effective than the menu-driven approach that has been proposed as a meager solution to enable the system to ask a question to the user. The proposed model assumes that when the system asks a question, it maintains an expectation of the potential answers. The system then uses the expectation as the focus to perform the most likely interpretation of the user's response. Without using such a focus the interpretation process could be unbounded. The interpretation process is mapped into a heuristic search problem. The interpretation process results in identifying a particular expectation-response relationship type, which the system can use to tailor its response strategy with respect to the given user-response. A prototype has been constructed to demonstrate the soundness of the proposed model 相似文献
100.
SiC(w)/TZP+mullite陶瓷复合材料界面和组成设计与力学性能 总被引:2,自引:1,他引:1
本文从理论上分析了SiC(w)TZP+mullite(p)复合材料界面残余热应力及其在基质内的分布规律。提出在SiC(w)表面涂复Al2O3和在PZT中加入mullite(p)联合作用来降低晶须/基质界面残余热应力的界面设计方案,导出SiC(w)和mullite(p)协同补强PZT的匹配条件。制备了SiC(w)/TZP+mullite(p)复合材料并了SiC(w)表面涂层Al2O3厚度和SiC(w 相似文献