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   1016篇
  免费   19篇
  国内免费   3篇
电工技术   113篇
综合类   2篇
化学工业   281篇
金属工艺   27篇
机械仪表   49篇
建筑科学   25篇
能源动力   77篇
轻工业   93篇
水利工程   1篇
石油天然气   2篇
无线电   54篇
一般工业技术   162篇
冶金工业   30篇
原子能技术   40篇
自动化技术   82篇
  2023年   4篇
  2022年   9篇
  2021年   15篇
  2020年   8篇
  2019年   9篇
  2018年   10篇
  2017年   16篇
  2016年   21篇
  2015年   15篇
  2014年   33篇
  2013年   75篇
  2012年   38篇
  2011年   55篇
  2010年   46篇
  2009年   41篇
  2008年   57篇
  2007年   52篇
  2006年   36篇
  2005年   36篇
  2004年   38篇
  2003年   47篇
  2002年   29篇
  2001年   22篇
  2000年   20篇
  1999年   28篇
  1998年   17篇
  1997年   23篇
  1996年   12篇
  1995年   17篇
  1994年   14篇
  1993年   12篇
  1992年   8篇
  1991年   10篇
  1990年   13篇
  1989年   5篇
  1988年   8篇
  1987年   15篇
  1986年   12篇
  1985年   13篇
  1984年   15篇
  1983年   11篇
  1982年   13篇
  1981年   7篇
  1980年   15篇
  1979年   7篇
  1978年   10篇
  1977年   4篇
  1976年   6篇
  1975年   2篇
  1969年   2篇
排序方式: 共有1038条查询结果,搜索用时 0 毫秒
31.
The equivalent circuit, the efficiency, and the important characteristics of moving pick‐up type contactless power transfer systems are described. If the primary series capacitor and the secondary parallel capacitors are chosen correctly and the winding resistances are ignored, the equivalent circuit of the transformer with these capacitors becomes the same as an ideal transformer at the resonant frequency. This simple approximation helps to understand the phenomena occurring with load changes. Because the circuit analysis becomes simple, the approximate value of the power transfer efficiency can be derived. This paper describes the determination of the capacitor values, the derivation of the equivalent circuit and the efficiency, and test results. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 172(2): 47–54, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20970  相似文献   
32.
To clarify the role of phosphate in the formation of corrosion products, the transformation of GRI(Cl) with the addition of phosphate was characterized through XRD, TEM, and solution analysis. Electrochemical analysis showed that the transformation of GRI(Cl) was delayed and the size of the final products, i.e., γ-FeOOH was reduced in the phosphate added case. X-ray absorption spectroscopy indicated that the neighboring Fe–Fe coordination number of FeO6 octahedral unit in γ-FeOOH was decreased. These effects of phosphate are attributed to its adsorption on GRI(Cl) and nucleated γ-FeOOH that prevented particle growth during oxidation process.  相似文献   
33.
The method has been developed to improve the bitumen product which incorporates an evaporator concentrate from a BWR, with respect to the swelling and leaching. The leachability of the product has been measured by the method recommended by the IAEA. The swelling of the product is successfully prevented by the addition of calcium chloride. The specimen containing the waste up to Wa/B (Weight ratio of Na2SO4 + CaCl2 and bitumen) = 60:40 shows no pronounced swelling, when it is immersed in water. The cumulative fractions of 137Cs and 60Co leached from a specimen which does not contain CaCl2 are 0.65 and 0.2 at the leaching time of 30 days. On the hand, the corresponding value at 100 days for the specimen with calcium chloride addition is 5 × 10?4 for 137Cs and 1 × 10?4 for 60Co. The coating of the specimen surface with a fresh bitumen (5 mm thickness) reduces the leachability further. These results indicate that this method is effective to improve the bitumen product incorporating BWR's evaporator concentrate.  相似文献   
34.
35.
Chemiluminescence (CL) detection integrated with a microchip capillary electrophoresis (MCE) system that was fabricated in poly(dimethylsiloxane) was demonstrated for chemical and biochemical analyses. Two model CL systems were involved here: metal ion-catalyzed luminol-peroxide reaction and dansyl species conjugated peroxalate-peroxide reaction. Different strategies based on three chip patterns (cross, cross combining with Y, and cross combining with V) to perform on-line CL detection for MCE were evaluated and compared in terms of sensitivity, reproducibility, and peak symmetry. The chip pattern of cross combining with Y proved to be promising for the luminol-peroxide CL system, while the chip pattern of cross combining with V was preferred for the peroxalate-peroxide system where CL reagent could not be effectively transported by electroosmotic flow. A detection limit down to submicromolar concentrations (midattomole) was achieved with good reproducibility and symmetric peak shape. Successful separation of three metal cations such as Cr(III), Co(II), and Cu(II) and chiral recognition of dansyl phenylalanine enantiomers within 1 min revealed distinct advantages of combining MCE with CL detection for rapid and sensitive analyses.  相似文献   
36.
We present conventional detection of 2,4-dinitrophenol (DNP) for using the competitive reaction between DNP and DNP-conjugated albumin onto DNP antibody immobilized quartz crystal microbalance (QCM). This QCM method allows detection of DNP concentration in the range of 0.01 to 100 ng/ml; linear correlation obtains DNP concentration from 1 to 100 ng/ml.  相似文献   
37.
Fast- switching reverse-conducting thyristors have been developed and used in dc chopper apparatus to control the speed of highvoltage dc traction motors. The newly developed dc chopper circuit and its application for low-voltage dc motor control are discussed. The fast-switching reverse-conducting thyristor is utilized as the main thyristor to control load current.  相似文献   
38.
本文从形态学的角度通过对哈尔滨近代建筑顶部形态(屋顶突出物和女儿墙)的细部构成的归纳、抽象,概括出其母题的基本类型;并根据统计结果,得出具有普遍性的形态母题。通过对整体关系的抽象,概括出其模式的基本类型;并根据统计结果,得出具有普遍性的关系模式;在上述定量分析的基础上,结合美学原理,对其所蕴含的美学意匠作了分析。  相似文献   
39.
Lysobacter sp. IB-9374, which was isolated from soil as a high lysyl endopeptidase-producing strain (Chohnanet al., FEMS Microbiol. Lett., 213, 13-20, 2002), was found to produce a beta-lytic protease capable of lysing gram-positive bacteria such as Staphylococcus aureus, Microccocuseus, and Bacillus subtilis. The Lysobacter strain secreted the beta-lytic protease into the culture medium at a 2.4-fold higher level than Achromobacter lyticus. The enzyme was highly purified through a series of six steps with a high yield. The enzyme was strongly inhibited by tetraethylene-pentamine and 1,10-phenanthroline. The purified enzyme lysed more efficiently almost all the gram-positive bacteria tested than lysozyme, lysostaphin, and mutanolysin. The enzyme was very similar to Achromobacter beta-lytic protease containing one zinc atom in terms of amino acid composition and N-terminal sequence. The nucleotide sequence revealed that the mature enzyme was composed of 179 amino acid residues with additional 198 amino acids at the amino-terminal end of the enzyme. The deduced amino acid sequence of the mature enzyme coincided with that of the Achromobacter enzyme, although the prepro-region showed a 41% sequence identity with the counterpart. These results indicate that Lysobacter sp. is a useful strain for an efficient large-scale preparation of beta-lytic protease capable of lysing bacteria.  相似文献   
40.
The aim of our study was to estimate the surface expressions of CD95 (APO-1/Fas) antigen and the intracellular expressions of anti-apoptotic protein Bcl-2 and pro-apoptotic protein Bax in CD4(+)CD25(+)FoxP3(+) T regulatory lymphocytes (Tregs) as well as the percentage of CD8(+)CD28(+) T cytotoxic cells in peripheral blood of patients with pre-eclampsia in comparison with healthy pregnant women in the third trimester of physiological pregnancy. Twenty-four women with pre-eclampsia and 20 normal third trimester pregnant women were included in the study. The lymphocytes were isolated from peripheral blood samples and labeled with monoclonal antibodies. The expressions of surface antigens and intracellular proteins were estimated using flow cytometry. The population of CD4(+)CD25(+)FoxP3(+) Treg cells was significantly lower in peripheral blood of patients with pre-eclampsia when compared to normal third trimester pregnant women. The percentages of CD4(+)CD25(+)FoxP3(+) Treg cells that express Bcl-2 protein were significantly lower in peripheral blood of patients with pre-eclampsia when compared to healthy pregnant women, whereas the percentages of CD4(+)CD25(+)FoxP3(+) Treg cells with the expressions of Bax protein did not differ in both groups. Moreover, the mean fluorescence intensity (MFI) of Bcl-2 protein in CD4(+)CD25(+)FoxP3(+) Treg cells was significantly lower and MFI of Bax protein significantly higher in pre-eclampsia when compared to the control group. The percentage of CD8(+)CD28(+) T cells did not differ in both studied groups but MFI of CD28 antigen on T CD8(+) cells was significantly higher in pre-eclampsia when compared to the control group. The obtained results suggest that the deficit of CD4(+)CD25(+)FoxP3(+) Treg lymphocytes which is observed in pre-eclampsia may be associated with altered apoptosis signaling in Tregs.  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