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   716篇
  免费   3篇
电工技术   3篇
化学工业   79篇
金属工艺   57篇
机械仪表   81篇
建筑科学   6篇
矿业工程   17篇
能源动力   11篇
轻工业   1篇
水利工程   12篇
石油天然气   80篇
无线电   74篇
一般工业技术   162篇
冶金工业   100篇
原子能技术   19篇
自动化技术   17篇
  2022年   5篇
  2021年   13篇
  2020年   16篇
  2019年   19篇
  2018年   29篇
  2017年   20篇
  2016年   21篇
  2015年   7篇
  2014年   21篇
  2013年   25篇
  2012年   26篇
  2011年   27篇
  2010年   33篇
  2009年   32篇
  2008年   30篇
  2007年   25篇
  2006年   20篇
  2005年   17篇
  2004年   17篇
  2003年   19篇
  2002年   9篇
  2001年   17篇
  2000年   20篇
  1998年   10篇
  1997年   9篇
  1996年   6篇
  1995年   5篇
  1993年   5篇
  1990年   9篇
  1989年   11篇
  1985年   7篇
  1983年   6篇
  1981年   6篇
  1980年   9篇
  1979年   11篇
  1978年   9篇
  1977年   12篇
  1976年   6篇
  1975年   13篇
  1974年   10篇
  1973年   15篇
  1972年   6篇
  1971年   5篇
  1970年   7篇
  1969年   7篇
  1968年   11篇
  1967年   5篇
  1966年   8篇
  1965年   4篇
  1964年   5篇
排序方式: 共有719条查询结果,搜索用时 46 毫秒
1.
The influence of the thermal cycling conditions on the thermal-cycling creep of a TN-1 alloy and the related irreversible deformations is studied. The conditions under which an anomalous increase in the irreversible deformations begins are determined. The structural mechanism of the irreversible deformations of an equiatomic alloy is shown to be analogous to the structural mechanism of metal creep at high temperatures: it predominantly has a dislocation character. It is proposed to use the effect of anomalous increase in the deformation of materials with reversible martensitic transformations for forming parts made of these materials at low temperatures.  相似文献   
2.
3.
Increasing attention at oil refineries is being focused on solving environmental problems caused by stiffening of the requirements for emissions of harmful substances into air and water. Advanced technologies that reduce the effect of industrial enterprises on the environment to the minimum are becoming increasingly in demand. Treatment of process wastewaters to remove hydrogen sulfide and ammonia is one such problem of the modern refinery with cat crackers. __________ Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 3, pp. 52–55, May–June, 2006.  相似文献   
4.
A technique is proposed for introducing microdoses (10?5–10?10 g) of germanium and indium metals into semiconductor compounds by coulometric titration in a solid electrolyte cell. The solid electrolytes that are reversible with respect to germanium cations (the GeSe-GeI2 system containing 5 mol % GeI2) and indium cations (the InCl3-MgCl2 system containing 15 mol % MgCl2, the InCl3-CdCl2 system containing 1.5 mol % CdCl2, and the In2S3-InCl3 system containing 5 mol % InCl3) are chosen, and their electric transport properties are characterized. The optimum conditions for electrochemical doping (temperature, current density), under which the current efficiency reaches 90–100%, are determined. The doping with germanium and indium is performed for nonstoichiometric compounds, such as lead monotelluride, indium sulfide, and ternary chalcogenide spinel Cd1 ± δCr2Se4. The doping efficiency is controlled by measuring the electromotive force of the corresponding electrochemical cells and the Hall effect, as well as using the electrical conductivity method. The solid electrolytes that are reversible with respect to indium are used to determine the standard Gibbs energies of formation of a number of indium-containing semiconductors.  相似文献   
5.
Porous carbon nanofibers are synthesized by CVD method from acetylene with use of iron-containing catalysts. Activation of the nanofibers in melted potassium hydroxide results in increasing surface area from initial 300–400 m2 g−1 to 1700 m2 g−1. As follows from XRD data, activated nanofibers do not contain regular packages of graphene layers, but retain high electric conductivity. Deposition of copper improves electrochemical hydrogen storing characteristics of carbon nanofibers. Carbon nanomaterials obtained can be used as hydrogen storing materials in batteries instead of hydride forming metals.  相似文献   
6.
The paper compares experimental and calculated pulse shapes and spectra of signals for bidirectional right transducers with radically different protectors, namely, those from epoxy glue with a filler and ceramic. The new data support the previously made conclusion (from calculated parameters of emitted pulses) that in protectors from composite materials (with low propagation velocities of longitudinal elastic waves) signal spectra can have several pronounced peaks, and their waveforms can exhibit beats (oscillating amplitude modulation).  相似文献   
7.
A theoretical study is reported of the magnetic-field-controlled optical transmission through a stack of identical bilayers in which one layer is bigyrotropic and the other is nonmagnetic and isotropic. An analytical expression for the complex transmittance is derived. The transmittance–wavelength characteristic is examined for different magnetizations and for fixed materials parameters and total number of bilayers. The magnetization dependence of the position, height, and width of the center peak is investigated. The effect is calculated of magnetization on the ellipticity of transmitted light and the angle of optical rotation.  相似文献   
8.
A polyfunctional catalyst for hydrorefining of the catalytic naphtha cut with a high olefin content is proposed. This catalyst induces isomerization and hydrogenation of olefins on contact with the feedstock with formation of isoparaffins, isomerization of n-paraffins, hydrotreating to remove sulfur, and other processes. The naphtha obtained satisfies the Euro-4 standard (2005) with respect to quality. __________ Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 5, pp. 35–3 6, September–October, 2007.  相似文献   
9.
We analyze various possibilities for improving the anticorrosive properties of metallic coatings, including alloying, modification of the base (prior to coating), the choice of the optimum (for producing anticorrosive structures) conditions of electrolysis, the use of multilayer coatings (sandwich-type structures), and modification of coatings by depositing passive layers by high-energy treatment (laser, electron-beam, plasmachemical, etc.).Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 30, No. 5, pp. 81–87, September – October, 1994.  相似文献   
10.
The directivity characteristic of a normal probe with a circular piezoelectric plate has been calculated with allowance for pressure (elastic stress) oscillations within both the excitation region (the surface of the electrodes applied to the piezoelectric plate) and the plate itself, whose dimensions exceed those of the excitation region. It is established that, in the first and second cases, the directivity characteristics are somewhat wider and narrower, respectively, than those used in the conventional stepwise approximation of the pressure applied from a transmitting probe to the surface of a tested article. The effective piezoelectric-plate size is estimated.  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