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   335篇
  免费   22篇
电工技术   10篇
化学工业   62篇
金属工艺   3篇
机械仪表   8篇
能源动力   9篇
轻工业   18篇
水利工程   1篇
无线电   25篇
一般工业技术   116篇
冶金工业   75篇
原子能技术   14篇
自动化技术   16篇
  2023年   1篇
  2022年   1篇
  2021年   4篇
  2020年   2篇
  2019年   2篇
  2018年   12篇
  2017年   3篇
  2016年   11篇
  2015年   5篇
  2014年   13篇
  2013年   15篇
  2012年   24篇
  2011年   22篇
  2010年   17篇
  2009年   11篇
  2008年   22篇
  2007年   12篇
  2006年   4篇
  2005年   4篇
  2004年   4篇
  2003年   4篇
  2002年   4篇
  2001年   5篇
  2000年   2篇
  1999年   12篇
  1998年   28篇
  1997年   16篇
  1996年   23篇
  1995年   4篇
  1994年   10篇
  1993年   2篇
  1992年   1篇
  1990年   1篇
  1989年   2篇
  1988年   2篇
  1987年   2篇
  1986年   2篇
  1985年   3篇
  1984年   1篇
  1983年   5篇
  1982年   5篇
  1981年   3篇
  1980年   5篇
  1979年   7篇
  1978年   7篇
  1977年   3篇
  1976年   6篇
  1975年   1篇
  1973年   1篇
  1972年   1篇
排序方式: 共有357条查询结果,搜索用时 31 毫秒
21.
Crack propagation velocity in delayed failure under superposed repeating load, (da/dt)R, was compared with that under static load, (da/dt)STwo peaks appear on the relation between decreasing rate of crack propagation velocity, 1-β = 1 ? (da/dt))R/(da/dt)S and frequency, ?, both under sinusoidal and square load. By changing the ratio of holding time at maximum stress intensity factor to that at minimum stress intensity factor in square load, it was deduced that the existence of two peaks on the 1 ? β vs f curve was caused by an asymmetric interaction between hydrogen atoms and cyclic moving of the position with triaxial tensile stress at crack tip. Moreover, the relation between 1 ? β and f under the positive or negative saw tooth load could be well explained by the interaction model.  相似文献   
22.
In three cases of oligodendrogliomas, atypical cells rich in eosinophilic cytoplasm, resembling plump astroyctic or astroblastic cells, were studied under the electron microscopy. These cells showed finely granular cytoplasm with routine hematoxylin-eosin preparation; ultrastructurally, they exhibited abundant, round cytoplasmic bodies of autophagic-vacuole type, in addition to other fine structures characteristic of oligodendroglioma cells.  相似文献   
23.
24.
The following effects were found for nickel deposition from NI(CF3COO)2-halide-MeOH bath:

The anode and cathode current efficiencies became higher by the addition of halide (NH4Cl, KBr, or NH4Br) into the Ni(CF3COO)2-MeOH bath.

Especially, the cathode current efficiency and the range of cd which can be obtained good nickel deposits became higher and wider respectively, by the addition of ammonium halide (NH4 or NH4Br).

The values of c and ioc for nickel deposition also became larger by the addition of ammonium halide. Therefore, it appears that the addition of ammonium halide facilitates the nickel deposition.

In view of n.=.1 and Ec.=.5kcal/mol in Tafel region, it may be concluded that the nickel deposition from the Ni(CF3COO)2-halide-MeOH bath takes place through Ni+.  相似文献   

25.
Seven microcalorimeters with different geometries have been tested and their performance is compared. The study, for TiAu TESs with a Cu absorber, indicates the presence of so-called constant voltage noise and internal thermal fluctuation noise. The constant voltage noise is not changed by a normal metal pattern on the TES, or by a magnetic field. The energy resolution of the detectors, having different heat capacities, is 2.5 and 5.0 eV (at 5.9 keV).   相似文献   
26.
An addition of a very small amount of Pr in Co-Ni films of a recording medium improves both corrosion resistance and frequency response. The columnar grains, which are induced by oblique incidence of evaporation, becomes remarkably finer by the addition of rare-earth elements. The TEM image of the cross section of the films shows a dense packed structure. High magnetization and a better corrosion resistance are considered to be due to the dense packed structure. The fine grain improves the frequency response. Among several rare-earth elements, especially Pr doping yields a best recording performance.  相似文献   
27.
Currently, wavelet transforms are widely used for the analyses of particle image velocimetry (PIV) velocity vector fields. This is because the wavelet provides not only spatial information of the velocity vectors, but also of the time and frequency domains. In this study, a discrete wavelet transform is applied to real PIV images of bubbly flows. The vector fields obtained by a self-made cross-correlation PIV algorithm were used for the discrete wavelet transform. The performances of the discrete wavelet transforms were investigated by changing the level of power of discretization. The images decomposed by wavelet multi-resolution showed conspicuous characteristics of the bubbly flows for the different levels. A high spatial bubble concentrated area could be evaluated by the constructed discrete wavelet transform algorithm, in which high-leveled wavelets play dominant roles in revealing the flow characteristics.  相似文献   
28.
29.
Lauryl sulfate and lauryl ether sulfate obtained by the sulfation of lauryl alcohol and lauryl alcohol ethoxylate are representative of anionic surfactants and are used as a formable detergent or an emulsifier. For the sulfation of lauryl alcohol and lauryl alcohol ethoxylate, SO3 gas, it was found that the quality of products was significantly influenced by the reaction conditions. In order to obtain good quality products we developed a new technology by using a new type of reactor called a “climbing film reactor,” in which SO3 gas and liquid raw material flow ascendingly.  相似文献   
30.
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