全文获取类型
收费全文 | 14961篇 |
免费 | 631篇 |
国内免费 | 632篇 |
专业分类
电工技术 | 647篇 |
综合类 | 565篇 |
化学工业 | 1256篇 |
金属工艺 | 984篇 |
机械仪表 | 2086篇 |
建筑科学 | 839篇 |
矿业工程 | 327篇 |
能源动力 | 669篇 |
轻工业 | 249篇 |
水利工程 | 74篇 |
石油天然气 | 202篇 |
武器工业 | 154篇 |
无线电 | 1086篇 |
一般工业技术 | 1522篇 |
冶金工业 | 407篇 |
原子能技术 | 132篇 |
自动化技术 | 5025篇 |
出版年
2024年 | 24篇 |
2023年 | 161篇 |
2022年 | 247篇 |
2021年 | 313篇 |
2020年 | 309篇 |
2019年 | 285篇 |
2018年 | 293篇 |
2017年 | 362篇 |
2016年 | 397篇 |
2015年 | 534篇 |
2014年 | 759篇 |
2013年 | 817篇 |
2012年 | 787篇 |
2011年 | 1128篇 |
2010年 | 756篇 |
2009年 | 909篇 |
2008年 | 944篇 |
2007年 | 1030篇 |
2006年 | 915篇 |
2005年 | 927篇 |
2004年 | 722篇 |
2003年 | 634篇 |
2002年 | 507篇 |
2001年 | 361篇 |
2000年 | 347篇 |
1999年 | 313篇 |
1998年 | 293篇 |
1997年 | 225篇 |
1996年 | 184篇 |
1995年 | 132篇 |
1994年 | 129篇 |
1993年 | 121篇 |
1992年 | 78篇 |
1991年 | 54篇 |
1990年 | 47篇 |
1989年 | 40篇 |
1988年 | 42篇 |
1987年 | 18篇 |
1986年 | 19篇 |
1985年 | 10篇 |
1984年 | 16篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
21.
After the break-up of Czechoslovakia in 1993 the primary metrological standards authority almost fully remained in Slovakia. So we had to build our primary vacuum metrology anew. But we could do it using uptodate techniques that are more effective and they enable us to fulfil our task more effectively and in a shorter time.The steady demand to widen the lower pressure range and a steady demand for maximal accuracy collide with the financial possibilities open to a small country. So it is impossible to follow the classical pattern for the vacuum standards: liquid columns, static expansion system and dynamic expansion system. But it is possible to utilize contemporary progress in construction of piston manometers. This enables us to discard liquid column and static expansion techniques in favour of piston technique [Tesar J, Prazak D. Vacuum 2002; 67: 311, Tesar J, Prazak D, Krajicek Z. In:Proceedings of international symposium on Pressure and Vacuum, 2003. p. 169, Tesar J, Repa P, Prazak D, Krajicek Z, Peksa L. Vacuum 2004; 76: 491.]. Such system fulfils all the needs of a little industrial country and is economically acceptable. 相似文献
22.
In this work we present the discrete models for dynamic fracture of structures built of brittle materials. The models construction is based on Voronoi cell representation of the heterogeneous structure, with the beam lattice network used to model the cohesive and compressive forces between the neighboring cells. Each lattice component is a geometrically exact shear deformable beam which can describe large rigid body motion and the most salient fracture mechanisms. The latter can be represented through the corresponding form of the beam constitutive equations, which are derived either at microscale with random distribution of material properties or at a mesoscale with average deterministic values. The proposed models are also placed within the framework of dynamics, where special attention is paid to constructing the lattice network mass matrix as well as the corresponding time-stepping schemes. Numerical simulations of compression and bending tests is given to illustrate the models performance. 相似文献
23.
随着设备高速化的日益发展,传统的螺杆设计方法及相应的供送特性评价体系已显落后。参照蜗型凸轮动力学性能的评价方法,建立了高速供送螺杆的动态性能评价体系,为高速化供送螺杆的设计提供了性能参照指标。 相似文献
24.
25.
光电摆角动态测量原理及其测量系统 总被引:4,自引:1,他引:3
本文阐述了用于测量物体摆角及摆心浮动量的光电动态实时测量原理,以及根据此原理研制的光电导弹喷管摆角动态测量系统。 相似文献
26.
It is shown that steady-state kinetic data do not allow the discrimination between the redox and associated mechanisms of the partial oxidation reactions. A discrimination between these mechanisms was performed using transient experiments. The obtained rate expressions are in agreement with experimental kinetic data for catalytic partial oxidation of o-xylene.
An influence of the conjugate oxidation of a catalyst surface on dynamics and kinetics of the heterogeneous catalytic oxidative reactions is considered. Computing simulation of methane oxidative coupling of methane reaction at lowered temperature and elevated pressure has been performed. It showed that the reaction order with respect to oxygen exceeding unity is consistent with the chain branching mechanism of the reaction in the presence of TiSi2 and TiB2 and showed the important role of the branching chain cycles in the low-temperature OCM reaction at elevated pressure. 相似文献
27.
本文对动、静态下混凝土坍落度损失的规律进行了研究,并从流变学的角度分析了外加剂对动、静态下混凝土坍落度损失的影响坍落度损失存在差别的原因. 相似文献
28.
Ana Mafalda RibeiroJosé Miguel Loureiro 《Chemical engineering science》2002,57(9):1621-1626
The system ASC carbon filter/cyanogen chloride was studied by simulation. Three filter configurations and several models, taking into account Langmuir adsorption and second-order reaction between the adsorbed toxic vapour and the active metal on the surface, were developed.The effects of axial dispersion, number of reaction units, film mass transfer units and intraparticle mass transfer resistance on the breakthrough time were studied.Simulation results show that a complex model should be used in order to predict with reasonable accuracy the protection imparted by these filters. 相似文献
29.
This paper reviews the characteristics of pulsating or cyclic flow of bulk solids during gravity discharge in bins and silos. The dynamic load phenomenon is often referred to as “silo quaking” and is influenced by various factors related to the type of flow pattern developed in the bin and the flow properties of the bulk material. Of particular relevance is the influence of ‘slip-stick’ during shear flow, and the velocity at critical sections in the silo during discharge. An overview of recent and current research on this subject is presented. 相似文献
30.
The paper addresses the design of two-level power system stabilizers using an optimal reduced order model whose state variables are torque angles and speeds. The reduced order model retains their physical meaning and is used to design a two-level linear feedback controller that takes into account the realities and constraints of electrical power systems. The two-level control strategy is used, and a global control signal is generated from the output variables to minimize the effect of interactions. The effectiveness of this controller is evaluated and a multimachine system is given as an example to illustrate the advantages of the proposed method. Responses of the system with a two-level scheme and an optimal reduced order scheme are included for comparative analysis. 相似文献