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   888篇
  免费   1篇
化学工业   114篇
金属工艺   45篇
机械仪表   18篇
建筑科学   6篇
矿业工程   33篇
轻工业   34篇
水利工程   46篇
石油天然气   72篇
无线电   20篇
一般工业技术   260篇
冶金工业   107篇
原子能技术   117篇
自动化技术   17篇
  2013年   6篇
  2007年   4篇
  2005年   7篇
  2004年   27篇
  2003年   29篇
  2002年   22篇
  2001年   20篇
  2000年   9篇
  1999年   4篇
  1998年   14篇
  1997年   12篇
  1996年   11篇
  1995年   16篇
  1994年   14篇
  1993年   20篇
  1992年   21篇
  1991年   20篇
  1990年   16篇
  1989年   31篇
  1988年   26篇
  1987年   19篇
  1986年   24篇
  1985年   20篇
  1984年   19篇
  1983年   26篇
  1982年   24篇
  1981年   21篇
  1980年   26篇
  1979年   32篇
  1978年   30篇
  1977年   29篇
  1976年   31篇
  1975年   21篇
  1974年   28篇
  1973年   35篇
  1972年   22篇
  1971年   19篇
  1970年   15篇
  1969年   23篇
  1968年   16篇
  1967年   14篇
  1966年   16篇
  1965年   11篇
  1964年   6篇
  1963年   6篇
  1962年   4篇
  1961年   5篇
  1960年   4篇
  1958年   2篇
  1957年   2篇
排序方式: 共有889条查询结果,搜索用时 15 毫秒
1.
An optoelectronic method is considered for noncontacting reconstruction of the surface profile of three-dimensional objects of large dimensions. The optimal conditions for performing measurements are identified. It is shown that the proposed method, in contrast to the already known methods, does not require fine tuning of the equipment. A numerical method is given for compensating distortions caused by aberrations. A method is described for reconstructing the surface profile cell by cell which increases the accuracy of measurements.  相似文献   
2.
Breakdown of a company is examined and the concept of its stability is given. A system of indexes for characterizing the market position of an enterprise in the chemical industry and predicting its dynamics is proposed. An integral index can be an effective tool in the hands of managers in making managerial decisions related to effectively reacting to changes in the company's market position.  相似文献   
3.
Gomzina  N. A.  Vasil'ev  D. A.  Krasikova  R. N. 《Radiochemistry》2002,44(4):403-409
Synthesis of 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) involving base hydrolysis was optimized. Fluorine-18 was isolated from irradiated water to more than 90% by sorption of [1 8F]fluoride on QMA anion-exchange resin, which was followed by elution with a 96 : 4 (by volume) acetonitrile-water mixture containing Kryptofix 2.2.2 and potassium carbonate (molar ratio 2 : 1). This composition is the best for preparing the complex [K/K2.2.2]+ 18F- used in nucleophilic fluorinations. No additional azeotropic drying is required. Base hydrolysis under optimized conditions (40-45°C), followed by neutralization with HCl, removal of traces of the solvent, and purification of the final product on a combined SCX/Alumina N column, yielded [1 8F]FDG of high radiochemical (>99%) and chemical purity with minimal product loss. With an RB-86 robotic system (Anatech, Sweden), the synthesis time was 38 min. The procedure is used in the Institute of Human Brain, Russian Academy of Sciences for routine synthesis of FDG; the radiochemical yield of the product by the end of synthesis (EOS) is reproducibly high: 63±3% (n = 40).  相似文献   
4.
The purpose and current construction status, at the Institute of Theoretical and Experimental Physics, of an experimental electronuclear setup, combining a pulsed proton linear accelerator (36 MeV, 0.5 mA) and a subcritical blanket thermal-power assembly 100 kW, are discussed. The main equipment is already available or is being built in industry. The setup can be used to investigate the dynamics of the interaction of a linac–driver and a subcritical reactor and problems concerning the accelerator–driver and the target–blanket assembly. The proton beams and neutron fluxes will be used for applied purposes. In the future it will be possible to increase substantially the current and energy of the proton beam.  相似文献   
5.
New thermodynamic data for the In–Sb system are obtained and compared with calculation results available in the literature. An isothermal vacuum cell and a procedure for electrolyte preparation are described which ensure high measurement accuracy.  相似文献   
6.
Studied in the course of one-stage epidemiologic survey of 1191 individuals were the threshold of gustatory sensitivity to table salt and nycterine natriuresis, relation of these indices to dietary habits, some risk factors for cardiovascular disorders and clinical parameters. Differing relations were established between gustatory sensitivity to table salt and natriuresis and age and gender of the examinees, the level of blood pressure, aggravated heredity in respect of arterial hypertension, smoking and alcohol abuse, this enabling one to embark upon a differential approach to dietetic correction of salt consumption.  相似文献   
7.
The halide phase in copper halide photochromic glasses is studied by the small-angle X-ray scattering (SAXS) technique. The dependences of the volume and composition of the halide phase on the temperature of primary heat treatment are determined. The temperature of the formation of a vacuum pore upon cooling from the temperature of primary heat treatment and the temperature of pore disappearance upon heating are investigated as functions of the size of the halide phase regions. The influence of the size of the halide phase regions and the temperature of secondary heat treatment on the crystallization temperature of the halide phase is elucidated. It is shown that the previously observed increase in the crystallization temperature of the halide phase with an increase in the size of the phase regions is associated with the change-over from homogeneous to heterogeneous crystallization. In turn, the mechanism of crystallization depends on the region where the vacuum pore is formed. In the case when the effective radii of drops are less than 130–140 Å, the vacuum pore is formed in the bulk of a liquid drop and the homogeneous crystallization occurs. The nuclei of heterogeneous crystallization arise when the formation of the vacuum pore is accompanied by the destruction of the vitreous matrix. This takes place when the radii of liquid drops are larger than 165–170 Å. The nuclei of heterogeneous crystallization disappear upon heat treatment of glasses at temperatures above 600°C. As a result, upon cooling from these temperatures, the homogeneous crystallization is observed in all cases and the crystallization temperature does not depend on the size of the halide phase regions.  相似文献   
8.
A problem of the Stefan type which describes heat and mass transfer in a porous body with the double phase transition liquid–ice–vapor has been formulated and solved.  相似文献   
9.
Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 7, pp. 1–2, July, 1992.  相似文献   
10.
The indirect immunofluorescent technique was used to study the distribution of the ascitic fluid antigen (AgD) on histological sections from surgical specimens of gastric and colon tumours from proximal to distal lines of resection. AgD was found in gastric tumours exceptionally in the tumour area and in colon cancer--both in the tumour stroma and in surrounding histologically normal mucosa.  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