全文获取类型
收费全文 | 166555篇 |
免费 | 11816篇 |
国内免费 | 6093篇 |
专业分类
电工技术 | 8690篇 |
技术理论 | 9篇 |
综合类 | 8717篇 |
化学工业 | 27226篇 |
金属工艺 | 9970篇 |
机械仪表 | 10047篇 |
建筑科学 | 9779篇 |
矿业工程 | 3929篇 |
能源动力 | 3641篇 |
轻工业 | 9310篇 |
水利工程 | 3134篇 |
石油天然气 | 9524篇 |
武器工业 | 1051篇 |
无线电 | 17492篇 |
一般工业技术 | 26733篇 |
冶金工业 | 11068篇 |
原子能技术 | 4825篇 |
自动化技术 | 19319篇 |
出版年
2024年 | 714篇 |
2023年 | 2316篇 |
2022年 | 4594篇 |
2021年 | 6200篇 |
2020年 | 4664篇 |
2019年 | 4016篇 |
2018年 | 5119篇 |
2017年 | 5573篇 |
2016年 | 5127篇 |
2015年 | 5635篇 |
2014年 | 7287篇 |
2013年 | 8878篇 |
2012年 | 9527篇 |
2011年 | 10223篇 |
2010年 | 8686篇 |
2009年 | 8517篇 |
2008年 | 8397篇 |
2007年 | 7888篇 |
2006年 | 7304篇 |
2005年 | 6238篇 |
2004年 | 4775篇 |
2003年 | 4700篇 |
2002年 | 4739篇 |
2001年 | 4319篇 |
2000年 | 3744篇 |
1999年 | 3313篇 |
1998年 | 2620篇 |
1997年 | 2207篇 |
1996年 | 1972篇 |
1995年 | 1732篇 |
1994年 | 1463篇 |
1993年 | 1242篇 |
1992年 | 1216篇 |
1991年 | 1075篇 |
1990年 | 1089篇 |
1989年 | 1009篇 |
1988年 | 896篇 |
1987年 | 841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 0 毫秒
102.
103.
The incidence of stress fractures is increasing among competitive and recreational athletes as well as among children and the elderly. By understanding the continuum of bone's response to stress and maintaining an appropriate index of suspicion, the health care provider can diagnose these injuries appropriately. An accurate history and examination is essential and will differentiate stress fractures from other stress reactions. The more common stress fractures are discussed. 相似文献
104.
In this paper we have studied the control of linear systems with algebraic-equation constraint. A pole-assignment controller with two-layer structure for such constrained systems has been presented. The objective of the controller is to assign the desired poles to constrained system and simultaneously force the corresponding closed-loop system to satisfy the constraint. The conditions for the existence of pole-assignment controller are discussed in different cases. The implementation algorithm of pole-assignment controller is also presented. An example is given to illustrate the validity of the method in this paper. 相似文献
105.
106.
107.
Yu. Medvedevskikh A. Bratus G. Hafiychuk A. Zaichenko A. Kytsya A. Turovski G. Zaikov 《应用聚合物科学杂志》2002,86(14):3556-3569
The kinetics of glycidyl methacrylate block polymerization to high conversion was experimentally investigated with variations of the photoinitiator concentration, temperature, and power of UV illumination. The kinetic curves of this polymerization process contain three characterized sections of coordinates of “conversion–time,” namely: The first one is practically linear to a conversion of ≈0.5, the second represents, by itself, the autoacceleration process, and the third presents the autodecelation process. An additional peculiarity of such a polymerization process is poor reproduction of the kinetic measurements. This reproduction does not correspond to instrumental error. Derivation of a kinetic model for block linear polymerization was done. This model is, quantitatively, in good agreement with all the data of the experimental material. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3556–3569, 2002 相似文献
108.
V. I. Timoshenko Yu. V. Knyshenko Yu. G. Lyashenko 《Journal of Engineering Physics and Thermophysics》1997,70(3):394-398
The effect of turbulizing asperities positioned on one of the walls of a plane channel on the intensity of exchange processes
near a smooth wall with injection of different working media is studied experimentally.
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 3, pp. 404–408, 1997. 相似文献
109.
A system for recognizing a large class of engineering drawings 总被引:9,自引:0,他引:9
Yuhong Yu Samal A. Seth S.C. 《IEEE transactions on pattern analysis and machine intelligence》1997,19(8):868-890
We present a system for recognizing a large class of engineering drawings characterized by alternating instances of symbols and connection lines. The class includes domains such as flowcharts, logic and electrical circuits, and chemical plant diagrams. The output of the system, a netlist identifying the symbol types and interconnections, may be used for design simulation or as a compact portable representation of the drawing. The automatic recognition task is divided into two stages: 1) domain-independent rules are used to segment symbols from connection lines in the drawing image that has been thinned, vectorized, and preprocessed in routine ways; 2) a drawing understanding subsystem works in concert with a set of domain-specific matchers to classify symbols and correct errors automatically. A graphical user interface is provided to correct residual errors interactively and to log data for reporting errors objectively. The system has been tested on a database of 64 printed images drawn from text books and handbooks in different domains and scanned at 150 and 300 dpi resolution 相似文献
110.
Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 137–145, September–October, 1993. 相似文献