全文获取类型
收费全文 | 592037篇 |
免费 | 9122篇 |
国内免费 | 1056篇 |
专业分类
电工技术 | 10686篇 |
综合类 | 582篇 |
化学工业 | 96626篇 |
金属工艺 | 23778篇 |
机械仪表 | 19030篇 |
建筑科学 | 13430篇 |
矿业工程 | 4387篇 |
能源动力 | 15093篇 |
轻工业 | 51316篇 |
水利工程 | 7196篇 |
石油天然气 | 15144篇 |
武器工业 | 41篇 |
无线电 | 61450篇 |
一般工业技术 | 120049篇 |
冶金工业 | 99350篇 |
原子能技术 | 14764篇 |
自动化技术 | 49293篇 |
出版年
2022年 | 4428篇 |
2021年 | 6556篇 |
2020年 | 4751篇 |
2019年 | 6053篇 |
2018年 | 10346篇 |
2017年 | 10536篇 |
2016年 | 11034篇 |
2015年 | 6930篇 |
2014年 | 11394篇 |
2013年 | 28344篇 |
2012年 | 17571篇 |
2011年 | 22795篇 |
2010年 | 18304篇 |
2009年 | 20026篇 |
2008年 | 20228篇 |
2007年 | 19752篇 |
2006年 | 17059篇 |
2005年 | 15352篇 |
2004年 | 14553篇 |
2003年 | 14256篇 |
2002年 | 13677篇 |
2001年 | 13163篇 |
2000年 | 12578篇 |
1999年 | 12305篇 |
1998年 | 28943篇 |
1997年 | 20896篇 |
1996年 | 16189篇 |
1995年 | 12330篇 |
1994年 | 11115篇 |
1993年 | 10856篇 |
1992年 | 8426篇 |
1991年 | 8171篇 |
1990年 | 8047篇 |
1989年 | 7835篇 |
1988年 | 7558篇 |
1987年 | 6822篇 |
1986年 | 6591篇 |
1985年 | 7445篇 |
1984年 | 6756篇 |
1983年 | 6477篇 |
1982年 | 5814篇 |
1981年 | 5953篇 |
1980年 | 5689篇 |
1979年 | 5761篇 |
1978年 | 5692篇 |
1977年 | 6264篇 |
1976年 | 7841篇 |
1975年 | 5140篇 |
1974年 | 4924篇 |
1973年 | 5015篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Martensite transformations proceeding in mechanically loaded TiNi-based alloys account for an “anomalous” character of the acoustic emission from the material, whereby cyclic transformations during the growth of mechanical stress in the course of the direct transition is accompanied by an increase, rather than by a decrease, in the acoustic emission energy. This behavior of the acoustic emission is evidence of a significant influence of the external stresses on the martensite transformations and the related energy dissipation process. 相似文献
994.
The state of the surface of n-GaAs crystals upon high-vacuum microwave plasmachemical (HVMWPC) etching in various gas mixtures and the influence of the semiconductor surface condition on the photoelectric characteristics of related metal-semiconductor-metal structures with double Schottky barrier (MSMDSB structures) are investigated. Dependence of the HVMWPC etching rate of the GaAs surface on the gas mixture composition and substrate temperature is determined. It is shown that the HVMWPC etching regime strongly influences the photoelectric properties of MSMDSB structures: the treatment can lead to either growth or drop in photosensitivity of the samples. Optimum etching regimes are established for which good semiconductor surface quality and high photosensitivity of the MSMDSB structures are retained at a high etching rate. 相似文献
995.
María P. Albano Liliana B. Garrido 《Journal of Materials Synthesis and Processing》2002,10(4):211-218
Si3N4powders coated with 6 wt% Y2O3and 4 wt% Al2O3were prepared by coprecipitation. The resulting powders were dispersed in water at different pH values and with addition of various amounts of ammonium polyacrylate (NH4PA) to produce 32 vol% slips. The influence of the amount of NH4PA solution added and pH on the rheological properties of 32 vol% coated Si3N4slips were studied. In addition, the sintered density of cast samples was determined and related to the degree of slip dispersion. The adsorption of the NH4PA on the coated particle surface was rather high and the surface became saturated near 0.86 mg/m2at pH 9.2. High NH4PA concentrations (1.7–3 wt%) were necessary to obtain well dispersed 32 vol% coated Si3N4slips at pH 9.2. The best stabilization was obtained with the addition of 2.3 wt% NH4PA; in this condition, the viscosity reached a minimum value of 35 mPa.s at 100 s–1. The slip viscosity increased with increasing pH from 9.2 to 10.2. Slips with low viscosities gave a more dense packing of cast samples and consequently higher sintered density values. 相似文献
996.
Characteristics of hydrostatic bearing/seal parts for water hydraulic pumps and motors. Part 1: Experiment and theory 总被引:2,自引:0,他引:2
In this paper, the load-carrying capacity, power losses and stiffness of disk-type hydrostatic thrust bearings including the case of eccentric loading are discussed theoretically. The numerical analysis method is established based on a two-dimensional elastohydrostatic problem with an elastic deformation model, which is extended to adapt it for a non-axisymmetric load acting on the thrust bearing. The bearing is made of a combination of stainless steel/stainless steel and stainless steel/plastics. For the elastic materials, the maximum stiffness derived from, i.e., minimum film thickness is, larger than that of the rigid material in the range of a large ratio of pocket pressure and a hydrostatic balance ratio of over unity, which is defined as the ratio of the load to the maximum hydrostatic load-carrying capacity. The maximum load-carrying capacity and minimum power loss can exist in the domain of the hydrostatic balance ratio over unity for the case of the bearing consisting of elastic/rigid materials, in comparison with that composed of the same rigid materials. For the case of water, the power loss due to leakage flow is slightly larger but that due to frictional torque is much smaller than that in the case of hydraulic oil. Then, the total power loss is much smaller than that of hydraulic oil. 相似文献
997.
A new system based on the harnessing of solar and wind power is presented for heat dissipation in air conditioning facilities. The innovation offered by the new system is the integration of two well-known subsystems: a cooling tower and a solar chimney which increases the air flow without the use of electric power. The system is described and presented together with a model for its study. The field data acquired from the prototype built in southern Spain establishes the actual potential of the system, which provides a new approach to a sustainable technological development. 相似文献
998.
999.
Effect of Thermohydrogen Treatment on the Structure and Properties of Titanium Alloy Castings 总被引:2,自引:0,他引:2
Il'in A. A. Skvortsova S. V. Mamonov A. M. Permyakova G. V. Kurnikov D. A. 《Metal Science and Heat Treatment》2002,44(5-6):185-189
Metal Science and Heat Treatment - 相似文献
1000.
We present methods to generate rendering sequences for triangle meshes which preserve mesh locality as much as possible. This is useful for maximizing vertex reuse when rendering the mesh using a FIFO vertex buffer, such as those available in modern 3D graphics hardware. The sequences are universal in the sense that they perform well for all sizes of vertex buffers, and generalize to progressive meshes. This has been verified experimentally. 相似文献