全文获取类型
收费全文 | 50024篇 |
免费 | 6306篇 |
国内免费 | 3984篇 |
专业分类
电工技术 | 6589篇 |
技术理论 | 1篇 |
综合类 | 5435篇 |
化学工业 | 4253篇 |
金属工艺 | 3383篇 |
机械仪表 | 3382篇 |
建筑科学 | 3433篇 |
矿业工程 | 1864篇 |
能源动力 | 2124篇 |
轻工业 | 1972篇 |
水利工程 | 1497篇 |
石油天然气 | 5608篇 |
武器工业 | 691篇 |
无线电 | 6194篇 |
一般工业技术 | 6006篇 |
冶金工业 | 1722篇 |
原子能技术 | 798篇 |
自动化技术 | 5362篇 |
出版年
2024年 | 258篇 |
2023年 | 819篇 |
2022年 | 1429篇 |
2021年 | 1616篇 |
2020年 | 1687篇 |
2019年 | 1457篇 |
2018年 | 1310篇 |
2017年 | 1831篇 |
2016年 | 1979篇 |
2015年 | 2066篇 |
2014年 | 2925篇 |
2013年 | 2968篇 |
2012年 | 3744篇 |
2011年 | 3931篇 |
2010年 | 2897篇 |
2009年 | 2970篇 |
2008年 | 2659篇 |
2007年 | 3358篇 |
2006年 | 3144篇 |
2005年 | 2635篇 |
2004年 | 2265篇 |
2003年 | 1981篇 |
2002年 | 1632篇 |
2001年 | 1391篇 |
2000年 | 1295篇 |
1999年 | 1122篇 |
1998年 | 839篇 |
1997年 | 750篇 |
1996年 | 663篇 |
1995年 | 558篇 |
1994年 | 485篇 |
1993年 | 345篇 |
1992年 | 267篇 |
1991年 | 212篇 |
1990年 | 199篇 |
1989年 | 187篇 |
1988年 | 116篇 |
1987年 | 55篇 |
1986年 | 44篇 |
1985年 | 33篇 |
1984年 | 32篇 |
1983年 | 15篇 |
1982年 | 23篇 |
1981年 | 16篇 |
1980年 | 18篇 |
1979年 | 13篇 |
1978年 | 8篇 |
1959年 | 11篇 |
1955年 | 7篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Y. Xiang Y. B. Zhao G. W. Wei 《International journal for numerical methods in engineering》2002,55(8):947-971
Part 2 of this series of two papers presents the applications of the discrete singular convolution (DSC) algorithm. The main purpose of this paper is to explore the utility, test the accuracy and examine the convergence of the proposed approach for the vibration analysis of rectangular plates with internal supports. Both partial internal line supports and complex internal supports are considered for 21 square plates of various combinations of edge support conditions. The effects of different size, shape and topology of the internal supports and different boundary conditions on the vibration response of plates are investigated. The partial internal line supports may vary from a central point support to a full range of cross or diagonal line supports. Several closed‐loop supports, such as ring, square and rhombus, and their combinations are studied for complex internal supports. Convergence and comparison studies are carried out to establish the correctness and accuracy of the DSC algorithm. The DSC results are compared with those in the available literature obtained by using other methods. Numerical results indicate that the DSC algorithm exhibits controllable accuracy for plate analysis and shows excellent flexibility in handling complex geometries, boundary conditions and support conditions. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
33.
介绍了天线近场测量的基本原理和HD-1型平面近场测试系统,并对近场测量在实际天线测试中的应用情况、发展方向和应用前景等作了简单的描述。 相似文献
34.
35.
Gyeong-Ho Kim 《Computer Methods in Applied Mechanics and Engineering》2008,198(2):234-244
A continuum-based modeling of coupled electrostatics-structure interactions is presented for the frequency computations of MEMS devices. The present general formulation of electrostatics accounting for free space is validated first by specializing it to one-dimensional uniform motion of conducting surfaces and comparing the resulting electrostatics to conventional lumped models. The general coupled electrostatics-structure interactions are then applied for the prediction of resonant frequencies of MEMS devices due to bias-voltage changes and temperature variations. Comparisons of predicted resonant frequencies obtained by the present coupled electrostatics-structure interaction models with experimental results available in the literature demonstrate that the proposed continuum-based interaction modeling yields high-confidence predictions of resonant frequencies of MEMS devices. 相似文献
36.
The transmission mode of holographic polymer‐dispersed liquid crystals (HPDLCs) was developed an under electric field. It is reported that orientation of LC molecules under an electric field induces orientation of oligomer molecules giving rise to low off‐state diffraction and small grating shrinkage. Copyright © 2005 Society of Chemical Industry 相似文献
37.
The d.c. electrical conductivity of sodium vanadate, rubidium vanadate, cesium vanadate and their solid solutions sodium-rubidium
vanadate and sodium-cesium vanadate were studied by a two-probe method in the temperature range covering their transition
points. The electrical conductivity shows sharp change at the phase transition temperature of these materials. In NaVO3, RbVO3 and CsVO3, increase in d.c. conductivity is observed in the ferroelectric region while nonlinearities are observed above transition
temperatures. In solid solutions, the activation energy in the paraelectric state is higher than that in the ferroelectric
state and depends upon sodium concentration. 相似文献
38.
A numerical solution of the inverse problem of the gravitational field at a single point is obtained using six field elements
for a point, a spherical cap, a differential spherical sector and a vertical segment. In the system of six equations obtained,
the unknowns are the mass of the body, the depth of its center, and the second, third, and fourth degree moments. The accuracy
of the solution of this system is ten times higher than when using three field elements.
__________
Translated from Izmeritel’naya Tekhnika, No. 5, pp. 3–8, May, 2007. 相似文献
39.
通过对汉口西商跑马场的调查,说明它移植武汉的经过和历程,以及它在建筑设计方面的一些特点。 相似文献
40.
ZHANG Liqing WU Xiaohua 《武汉理工大学学报(材料科学英文版)》2005,20(3):119-121
1IntroductionWuweizi is a traditional Chinese herb,usually usedto cure cough,asthma,neurasthenic,hepatitisetc.Theactive ingredients in wuweizi are5%-22%lignan,themain components of which include deoxyschizandrin,schizandrin andγ-Schizandrin.Forthe purpos… 相似文献