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   519篇
  免费   22篇
  国内免费   2篇
电工技术   26篇
综合类   1篇
化学工业   164篇
金属工艺   18篇
机械仪表   7篇
建筑科学   6篇
能源动力   22篇
轻工业   24篇
无线电   32篇
一般工业技术   80篇
冶金工业   99篇
原子能技术   10篇
自动化技术   54篇
  2023年   6篇
  2022年   4篇
  2021年   15篇
  2020年   4篇
  2019年   5篇
  2018年   9篇
  2017年   5篇
  2016年   7篇
  2015年   14篇
  2014年   19篇
  2013年   36篇
  2012年   17篇
  2011年   27篇
  2010年   15篇
  2009年   16篇
  2008年   20篇
  2007年   16篇
  2006年   16篇
  2005年   17篇
  2004年   10篇
  2003年   20篇
  2002年   11篇
  2001年   9篇
  2000年   9篇
  1999年   17篇
  1998年   35篇
  1997年   30篇
  1996年   18篇
  1995年   12篇
  1994年   18篇
  1993年   11篇
  1992年   6篇
  1991年   3篇
  1990年   5篇
  1989年   7篇
  1988年   9篇
  1987年   4篇
  1986年   6篇
  1985年   2篇
  1982年   7篇
  1981年   3篇
  1980年   3篇
  1979年   1篇
  1978年   5篇
  1977年   3篇
  1976年   5篇
  1974年   2篇
  1973年   1篇
  1972年   2篇
  1971年   1篇
排序方式: 共有543条查询结果,搜索用时 15 毫秒
61.
In this study, a 5.9‐inch foldable active‐matrix organic light emitting diode (AMOLED) display was developed. A folding test was performed repeatedly. The display survived the folding test (100,000 folds) with a curvature radius of 2 mm. To protect an organic light emitting diode (OLED) against moisture, inorganic passivation layers are provided on the upper and lower sides of the flexible display. Using our transfer technology, high density passivation layers can be obtained. The measured water vapor transmission rate of the layer is 7 × 10?6 g/m2?day or less, which improves OLED reliability. With these techniques, we have developed a book‐type display, which is repeatedly foldable like a book, and a tri‐fold display including a display area, which is foldable in three.  相似文献   
62.
The ionic conduction of oxygen in the ceria-alkaline earth oxide system was investigated as a function of temperature, partial pressure of oxygen and oxide composition, together with its crystal structure, density, and microstructure. Undoped ceria and its solid solution with alkaline earth oxides have a cubic fluorite structure. The ionic conductivity of ceria is greatly enhanced by additions of calcia and strontia, even when they are added in excess of the solubility limit. The conductivities of ceria-calcia and ceria-strontia were much higher than those of calcia-and yttria-stabilized zirconia. Up to the limit of calcia and strontia, the ionic transference number was nearly unity in the temperature range between 600 and 900°C. With an increase in calcia and strontia content, the ionic conductivity was little affected by the presence of a second phase of CaO and SrCeO3.  相似文献   
63.
Four different finite-difference (FD) approximations and a finite-element (FE) scheme are compared with regard to their accuracy. The relative accuracy of the different schemes is problem dependent and it is not possible to estimate, a priori the accuracy of a given scheme. In the case of finite-differences first, second, fourth and sixth order approximations are used. In the case of finite-elements a non-upwinding artificial viscosity is used. The different numerical schemes have been applied to the simulation of the flow in a lid-driven cavity and in a bifurcating channel. In the former case, the absolute accuracy of each scheme could be determined. The FD scheme with upwinding turned out to be more accurate only for low Reynolds numbers (Re), whereas the artificial viscosity used with the FE is relatively more accurate with increasing Re. In the case of the bifurcating channel the FD and the FE schemes use different types of boundary conditions. Nevertheless the agreement between the results is, graphically, very good.  相似文献   
64.
Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.  相似文献   
65.
66.
We have been developing array technology for fabricating magnetic calorimeters for X-ray astronomy. The magnetization change in each pixel of the paramagnetic sensor material due to the heat input of an absorbed X-ray is sensed by a meander shaped coil. With this geometry it is possible to obtain excellent energy sensitivity, low magnetic cross-talk and large format arrays fabricated on wafers that are separate from the SQUID read-out. A magnetic bias field for each pixel is generated by the use of a persistent current that is stored. We report on the results from our prototype arrays, which are coupled to low noise DC-SQUIDs. The first test results are presented and the sensitivity is compared with calculations.  相似文献   
67.
Spherical powders of aluminum oxynitride/nitride are directly prepared by flame synthesis in which oxygen serves as an indispensable reactant. Nonoxide powders are commonly nonspherical, and the particle sizes of these powders are less than submicrometers. The major limiting factors for the synthesis are the free energy, reaction temperature, and reaction rate. The innovative issue related to this flame technology that is assisted by plasma is the ambivalence of the reducing gas atmosphere over 1500 K. The chemical equilibrium calculated indicates that the plasma heating compensates for the lack of reaction temperature under a low-oxygen condition. This burner realizes a high-speed reaction with the help of the reactive species in the arcs.  相似文献   
68.
To determine whether plasma levels of total bile acids may provide a useful index for hypergalactosaemia due to porto-systemic shunts, these levels were determined in hypergalactosaemic neonates. Increased levels were found in all cases with portohepatic venous or portocaval shunts. The levels of both total bile acids and galactose were normalized when the shunts disappeared on the echograms. Both bile acids and galactose are almost completely absorbed by the liver via the first portal blood passage. Portosystemic shunts contribute to elevated levels of bile acids and galactose. CONCLUSION: Increased plasma levels of total bile acids serve as a diagnostic clue to the presence of portosystemic shunts in neonates with hypergalactosaemia.  相似文献   
69.
70.
Higher order effects such as third-order dispersion, shock effect, and soliton self-frequency shift on all-optical logic gates that use asymmetric nonlinear optical fiber couplers are investigated with the beam propagation method, and it is found that third-order dispersion seriously affects the operations of logic devices. In contrast to the case of nonvanishing third-order dispersion, the radiation is stimulated, and consequently the operations of the logic devices are degraded. In order to diminish the degradation, the bandwidth limited amplification is introduced. The logic functions can be improved by trapping only the soliton components in the finite gain-bandwidth  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