全文获取类型
收费全文 | 10297篇 |
免费 | 1363篇 |
国内免费 | 1030篇 |
专业分类
电工技术 | 427篇 |
综合类 | 1383篇 |
化学工业 | 351篇 |
金属工艺 | 341篇 |
机械仪表 | 1759篇 |
建筑科学 | 415篇 |
矿业工程 | 244篇 |
能源动力 | 177篇 |
轻工业 | 215篇 |
水利工程 | 226篇 |
石油天然气 | 178篇 |
武器工业 | 251篇 |
无线电 | 1405篇 |
一般工业技术 | 1025篇 |
冶金工业 | 264篇 |
原子能技术 | 107篇 |
自动化技术 | 3922篇 |
出版年
2024年 | 40篇 |
2023年 | 186篇 |
2022年 | 252篇 |
2021年 | 306篇 |
2020年 | 358篇 |
2019年 | 312篇 |
2018年 | 295篇 |
2017年 | 337篇 |
2016年 | 396篇 |
2015年 | 488篇 |
2014年 | 663篇 |
2013年 | 638篇 |
2012年 | 878篇 |
2011年 | 800篇 |
2010年 | 626篇 |
2009年 | 637篇 |
2008年 | 650篇 |
2007年 | 763篇 |
2006年 | 611篇 |
2005年 | 584篇 |
2004年 | 480篇 |
2003年 | 379篇 |
2002年 | 295篇 |
2001年 | 288篇 |
2000年 | 254篇 |
1999年 | 221篇 |
1998年 | 159篇 |
1997年 | 157篇 |
1996年 | 105篇 |
1995年 | 87篇 |
1994年 | 117篇 |
1993年 | 60篇 |
1992年 | 47篇 |
1991年 | 44篇 |
1990年 | 33篇 |
1989年 | 28篇 |
1988年 | 20篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 18篇 |
1984年 | 13篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1962年 | 2篇 |
1959年 | 4篇 |
1956年 | 2篇 |
1955年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
The scale along the coordinate axes in the equations of motion hitherto used for an H-maser (in relative units) is shown to depend on Q as the quality factor for an H-maser. This hinders both analysis of the operation of the H-maser and optimization of its parameters. The modified equations of motion proposed here do not have that shortcoming. We determine the atomic flux into the bulb that gives the H-maser the best metrological characteristics. 相似文献
2.
S V Bhat 《Bulletin of Materials Science》1994,17(7):1271-1285
When examined using continuous wave electron paramagnetic resonance and nuclear magnetic resonance spectrometers, the highT
c superconductors give rise to intense, low field, ‘non-resonant’ absorption signals in the superconducting state. This phenomenon
can be used as a highly sensitive, contactless technique for the detection and characterization of superconductivity even
in samples containing only minute amounts of the superconducting phase. Further, it can also be applied to the determination
of material parameters of interest such asJ
c andH
c2 in addition to being a powerful way of distinguishing between weak-link superconductivity and bulk superconductivity. The
details of these aspects are discussed. 相似文献
3.
G. M. Kulikov S. V. Plotnikova 《International journal for numerical methods in engineering》2002,55(10):1167-1183
The precise representation of rigid body motions in the displacement patterns of curved Timoshenko–Mindlin (TM) shell elements is considered. This consideration requires the development of the strain–displacement relationships of the TM shell theory with regard to their consistency with the rigid body motions. For this purpose a refined TM theory of multilayered anisotropic shells is elaborated. The effects of transverse shear deformation and bending‐extension coupling are included. The fundamental unknowns consist of five displacements and eight strains of the face surfaces of the shell, and eight stress resultants. On the basis of this theory the simple and efficient mixed models are developed. The elemental arrays are derived using the Hu–Washizu mixed variational principle. Numerical results are presented to demonstrate the high accuracy and effectiveness of the developed 4‐node shell elements and to compare their performance with other finite elements reported in the literature. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
4.
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
5.
Sebastián López Gustavo M. Callicó Félix Tobajas Valentín de Armas José F. López Roberto Sarmiento 《ETRI Journal》2008,30(6):862-864
This letter presents a novel approach for organizing computational resources into groups within H.264/AVC motion estimation architectures, leading to reductions of up to 75% in the equivalent gate count with respect to state‐of‐the‐art designs. 相似文献
6.
Why are human observers particularly sensitive to human movement? Seven experiments examined the roles of visual experience and motor processes in human movement perception by comparing visual sensitivities to point-light displays of familiar, unusual, and impossible gaits across gait-speed and identity discrimination tasks. In both tasks, visual sensitivity to physically possible gaits was superior to visual sensitivity to physically impossible gaits, supporting perception-action coupling theories of human movement perception. Visual experience influenced walker-identity perception but not gait-speed discrimination. Thus, both motor experience and visual experience define visual sensitivity to human movement. An ecological perspective can be used to define the conditions necessary for experience-dependent sensitivity to human movement. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
8.
通过构造一族辅助风险溢价来确定不定权益的无套利价格,用这种方法 讨论了存在交易限制时欧式不定权益的定价问题,其结果与Davis的公平价格一致. 相似文献
9.
模拟光耦SLC800在转台系统中的应用 总被引:1,自引:0,他引:1
在大功率转台控制系统中.存在着较大的电压干扰和电磁兼容问题。在转台的控制精度和驱动功率不断提高的情况下.本文使用模拟光耦隔离器件SLC800重新设计了转台中的某部分模拟电路.将功率放大电路和控制电路隔开,来增强系统的抗干扰能力和运行的可靠性。实验结果的分析和转台的运行表明:应用模拟光耦进行隔离,有效地消除了转台控制中的干扰和电磁兼容。 相似文献
10.
A method for the time suboptimal control of an industrial manipulator from an initial position and orientation to a final
position and orientation as it moves along a specified path is proposed. Nonlinear system equations that describe the manipulator
motion are linearized at each time step along the path. A method which gives the control inputs (joint angular velocities)
for time suboptimal control of the manipulator is developed. In the formulation, joint angular velocity and acceleration limitations
are also taken into consideration. A six degree of freedom elbow type manipulator is used in numerical examples to verify
the method developed. 相似文献