首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   707篇
  免费   5篇
电工技术   2篇
化学工业   97篇
金属工艺   56篇
机械仪表   14篇
建筑科学   5篇
矿业工程   10篇
能源动力   3篇
轻工业   8篇
水利工程   4篇
石油天然气   38篇
无线电   28篇
一般工业技术   210篇
冶金工业   194篇
原子能技术   17篇
自动化技术   26篇
  2019年   8篇
  2018年   15篇
  2017年   17篇
  2016年   7篇
  2014年   12篇
  2013年   25篇
  2012年   20篇
  2011年   21篇
  2010年   15篇
  2009年   24篇
  2008年   20篇
  2007年   15篇
  2006年   14篇
  2005年   8篇
  2004年   12篇
  2003年   9篇
  2002年   11篇
  2001年   10篇
  2000年   12篇
  1998年   15篇
  1997年   11篇
  1996年   7篇
  1995年   10篇
  1992年   12篇
  1991年   12篇
  1990年   13篇
  1989年   10篇
  1988年   12篇
  1987年   9篇
  1986年   13篇
  1985年   7篇
  1984年   12篇
  1983年   19篇
  1982年   7篇
  1981年   8篇
  1980年   10篇
  1979年   13篇
  1978年   14篇
  1977年   15篇
  1976年   14篇
  1975年   21篇
  1974年   19篇
  1973年   15篇
  1972年   10篇
  1971年   21篇
  1970年   12篇
  1969年   8篇
  1968年   11篇
  1967年   7篇
  1966年   21篇
排序方式: 共有712条查询结果,搜索用时 31 毫秒
1.
Nonlinear oscillation of aerosol in the vicinity of a resonance frequency that is twice lower than the first eigenfrequency (subharmonic resonance) is experimentally investigated in tubes with different conditions at the ends. The time dependence of the number density of aerosol droplets is determined, and the effect of the frequency and intensity of oscillation on the process of coagulation of droplets is studied. The nonmonotonic pattern of the dependence of the time of coagulation of aerosol droplets on the frequency of excitation with a minimal value at resonance is found. Ordered space-time structures (alternation of denser and looser regions of aerosol) are revealed in the visible region in the vicinity of the middle of a closed tube.  相似文献   
2.
The influence which the composition of powder mixtures, the treatment conditions which the mixtures are subjected to, and the conditions under which the hot-pressed composite materials B4C – (5-10 mass%) calcium-silicon are fabricated exert on the structure, nature of failure, and mechanical properties of these materials is investigated. Optimum properties are possessed by material containing 10 mass% of addition. It is shown that the structure, morphology, and dispersivity, as well as the nature of the distribution of the components that are added to the composite material (secondary phase) vary as the temperature of hot pressing changes. Maximal mechanical characteristics of the composite material (σbend = 560 MPa, K 1c = 4.7 MPa·m1/2, HV = 37 GPa) are attained at hot-pressing temperatures in the range 2000-2100°C.  相似文献   
3.
Investigated all links of oxygen homeostasis of patients in early period afterwards surgical stoppage gastro-intestinal bleeding and urgent intravascular volume replacement. Macrodelivery of oxygen (DO2) was reduced in two and more time in comparison with norm predominant in connection with anemia. In spite of the infringement of transport of oxygen through alveolar-capillary membrane (especially in patients with complications and death in early postoperative period), little affected of degree of hemoglobin saturation by oxygen. Despite decrease of erythrocyte zeta-potential, largely expressed in cases of lethal outcome, considerable infringement of passage through microcirculation vessels is fixed was not. The increase of degree of morbidity and anaerobic metabolism in early postoperative period was accompanied of hyperdynamic hemodynamic reaction. The increase of degree of morbidity was accompanied of increase oxygen deficit owing to infringement of oxidoreduction in fabries also.  相似文献   
4.
The effect of thickness of magnetic conductor and number of electrically insulating layers on the magnetic properties in an alternating field of a layered powder-metallurgy soft-magnetic material based on iron was investigated. It was determined that increasing the thickness of the magnetic conductor and frequency of the alternating current deteriorated the magnetic properties of the material. Creation of a layered structure in which ferromagnetic layers alternate with electrically insulating layers decreased specific magnetic losses.  相似文献   
5.
Translated from Atomnaya Énergiya, Vol. 67, No. 5, pp. 358–359, November, 1989.  相似文献   
6.
7.
The superconducting dipoles developed as part of the UNK project have reached a magnetic field 6 T at a rate of up to 0.8 T/sec. Experimental data are presented on the conditioning, rate dependences, and dynamic losses for magnets with two types of superconducting cable (zebra and oxide). Possible ways to decrease the heat release in a dipole operating in rapid-cycling magnetic fields are examined. The results of an analysis of heat release and temperature conditions are presented for a dipole with a winding made of improved current-carrying components.  相似文献   
8.
9.
Electron microscopic investigation of the rabbit [correction of rat] thoracic aorta revealed endothelium to be most vulnerable to the damage in experimental hypercholesterolemia. Administration of precursor of nitric oxide L-arginine against the background of hypercholesterolemia resulted in activation of functional activity of the endothelium of aorta. This notion is supported by an increase of the quantity of protein-synthesizing structures (ribosomes, polysomes, canaliculi of endoplasmic network), secretory granules vs rabbits on atherogenic diet. At stimulation of NO-synthase activity of endothelium the dilatory reactions of aortal strips to acetylcholine are improved.  相似文献   
10.
The aim of the work was to develop on-line methods of control and diagnostics of pressure sensors at a NPP. The analysis was carried out along two lines:
1. i) The detection system including the sensor itself was modeled theoretically to obtain and study its transfer function, and to establish correspondence between the spectral characteristics of the pressure signal.
2. ii) The numerical processing of the signal using the AR technique to reconstruct the transfer function and evaluate the system's response, to a step impulse, as well as the spectral analysis. The hydraulic model presented indicate that the spectral lines observed at 10 Hz are due to longitu-dinal oscillations of water in the system branches, while the response time of the detection system is effectively the time of signal retardation in the porous ceramic diaphragms of the δ-cell of the sensor itself.
  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号