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   70篇
  免费   0篇
电工技术   1篇
化学工业   10篇
机械仪表   2篇
能源动力   3篇
轻工业   3篇
无线电   1篇
一般工业技术   16篇
冶金工业   25篇
原子能技术   7篇
自动化技术   2篇
  2014年   4篇
  2013年   11篇
  2012年   1篇
  2011年   2篇
  2010年   2篇
  2009年   1篇
  2008年   1篇
  2006年   3篇
  2005年   1篇
  2004年   2篇
  2003年   1篇
  2002年   2篇
  2001年   2篇
  1999年   5篇
  1998年   10篇
  1997年   6篇
  1996年   4篇
  1994年   3篇
  1993年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1981年   1篇
  1979年   1篇
  1976年   2篇
排序方式: 共有70条查询结果,搜索用时 343 毫秒
21.
Serum GH levels were measured in 14 acromegalic patients in ITT, TRH test, LH-RH test, arginine test, OGTT, exercise test, CPZ test and PEG. More than 50% increase of serum GH level was observed in 3 of 13 ITT, 8 of 14 TRH test, 6 of 14 LH-RH test, 2 of 12 arginine test, 2 of 9 OGTT and 2 of 7 PEG. Only 2 out of 7 cases showed more than 50% decrease of serum GH level in CPZ test. Striking GH responses were observed in TRH and LH-RH test. Five of 14 cases showed more than 100% increase of serum GH level in TRH test but they did not have a significant response to LH-RH. Four of 14 cases also had more than 100% increase in LH-RH test with no significant response to TRH. The rest of the cases (5 cases) did not have marked response to either TRH or LH-RH. According to these results, serum GH responses of acromegalic patients could be devided into 30 types, 1) TRH responding type, 2) LH-RH responding type, 3) no response type.  相似文献   
22.
In this study, the composite magnetic nanoparticles of coated SiO nano film with about 8 nm size and high saturation magnetization value, were synthesized by liquid phase precipitation method. The magnetic nanoparticles can be dispersed in various liquid media, widely known as magnetic fluids or ferrofluids with both magnetic and liquid properties. The materials been collected great interests and more and more attentions to focus into Drug Delivery System (DDS) as a new technology in this paper. We use the composite nanoparticles to disperse H2O and inject the solutions into rat's in-vivo organs. And, in the experiments by using a strong photon beam of SPring-8 Synchrotron Radiation facility, the distribution stat and the effects of magnetic field as well as drug delivery behaviour of nanoparticles in the rat' kidney are verified by the in-vivo observations.  相似文献   
23.
Amphibacillus xylanus Ep01, a facultative anaerobe we recently isolated, shows rapid aerobic growth even though it lacks a respiratory pathway. Thus, the oxidative consumption of NADH, produced during glycolysis and pyruvate oxidation, should be especially important for maintenance of intracellular redox balance in this bacterium. We purified a flavoprotein functional as NADH oxidase from aerobically growing A. xylanus Ep01. The A. xylanus enzyme is a homotetramer composed of a subunit (M(r) 56,000) containing 1 mol of flavin adenine dinucleotide. This enzyme catalyzes the reduction of oxygen to hydrogen peroxide with beta-NADH as the preferred electron donor and exhibits no activity with NADPH. The flavoprotein gene of A. xylanus Ep01 was cloned by using a specific antibody. The amino acid sequence of 509 residues, deduced from the nucleotide sequence, showed 51.2 and 72.5% identities to the amino acid sequences of alkyl hydroperoxide reductase from Salmonella typhimurium and NADH dehydrogenase from alkalophilic Bacillus sp. strain YN-1, respectively. Bacillus spp. have a respiratory chain and grow well under aerobic conditions. In contrast, Amphibacillus spp., having no respiratory chain, grow equally well under both aerobic and anaerobic conditions, which distinguishes these two genera. Salmonella spp., which are gram-negative bacteria, are taxonomically distant from gram-positive bacteria such as Bacillus spp. and Amphibacillus spp. The above findings, however, suggest that the flavoprotein functional as NADH oxidase, the alkyl hydroperoxide reductase, and the NADH dehydrogenase diverged recently, with only small changes leading to their functional differences.  相似文献   
24.
A new concentrator receiver containing a 7 mm×7 mm 3J concentrator solar cell with a 37.4% peak efficiency was developed. The receiver design includes a homogenizer, heat-handling (epoxy lamination) technologies and a low-resistance soldered connection and can be applied to various concentrator optics, including dish systems. The outdoor efficiency with a combination of a plastic Fresnel lens, made by low-cost injection molding, reached 27% on a hot summer day under 35.0 °C ambient temperature without additional cooling. With this newly developed receiver, mechanical engineers will be able to design their own concentrator module suitable for their environment, using their mechanical knowledge and local industrial resources. A 400X and 7056 cm2 concentrator module was fabricated with 36 concentrator receivers connected in series and the same number of newly developed dome-shaped, non-imaging Fresnel lenses. The power rating was 200 Wp. The peak outdoor efficiency on a clear sky day was 26.8±1.5%. The integrated efficiency over the course of the day was 25.3±1.4%. This is the highest module efficiency that has been achieved using a practical module size and electrical rating.  相似文献   
25.
GDP-L-Fuc:N-acetyl-beta-D-glucosaminide alpha1-->6fucosyltransferase (alpha1-6FucT; EC 2.4.1.68), which catalyzes the transfer of fucose from GDP-Fuc to N-linked type complex glycopeptides, was purified from a Triton X-100 extract of porcine brain microsomes. The purification procedures included sequential affinity chromatographies on GlcNAcbeta1-2Manalpha1-6(GlcNAcbeta1-2Manalpha1- 2)Manbeta1-4GlcNAcbet a1-4GlcNAc-Asn-Sepharose 4B and synthetic GDP-hexanolamine-Sepharose 4B columns. The enzyme was recovered in a 12% final yield with a 440, 000-fold increase in specific activity. SDS-polyacrylamide gel electrophoresis of the purified enzyme gave a major band corresponding to an apparent molecular mass of 58 kDa. The alpha1-6FucT has 575 amino acids and no putative N-glycosylation sites. The cDNA was cloned in to pSVK3 and was then transiently transfected into COS-1 cells. alpha1-6FucT activity was found to be high in the transfected cells, as compared with non- or mock-transfected cells. Northern blotting analyses of rat adult tissues showed that alpha1-6FucT was highly expressed in brain. No sequence homology was found with other previously cloned fucosyltransferases, but the enzyme appears to be a type II transmembrane protein like the other glycosyltransferases.  相似文献   
26.
Layered hexaniobate K4Nb6O17 was modified with dodecylammonium ions and octadecyltrimethoxysilane molecules, which were held in the interlayer spaces by electrostatic interactions and covalent attachment to the layers, respectively. Interlayer spacing of the niobate was expanded by incorporation of the bulky organic species. Vapor adsorption isotherms of benzene and water indicated hydrophobic interlayer microenvironments of the organically modified niobates. Both of the modified niobates fairly adsorbed phenol dissolved in water. The photocatalytic activity of hexaniobate allowed the organically modified materials to photocatalytically decompose phenol upon UV irradiation. Decomposition time courses and quantitative analysis of phenol present in the system indicated that the phenol molecules adsorbed on the niobates were preferentially degraded. XRD and IR analyses of the modified niobates indicated that the silylated niobate was more durable than the ion-exchanged sample; the former kept the structure during the photocatalytic process while the latter was partly collapsed.  相似文献   
27.
Several MOP ligands 5 containing aryl groups at 2′ position of (R)‐2‐(diphenylphosphino)‐1,1′‐binaphthyl skeleton were prepared and used for palladium‐catalyzed asymmetric hydrosilylation of cyclic 1,3‐dienes 6 with trichlorosilane. Highest enantioselectivity was observed in the reaction of 1,3‐cyclopentadiene ( 6a ) catalyzed by a palladium complex (0.25 mol %) coordinated with (R)‐2‐(diphenylphosphino)‐2′‐(3,5‐dimethyl‐4‐methoxyphenyl)‐1,1′‐binaphthyl ( 5f ), which gave (S)‐3‐(trichlorosilyl)cyclopentene of 90% ee.  相似文献   
28.
K. Uozumi 《Thin solid films》1979,57(1):141-146
A series-connected islands model is proposed to account for the field effect of the electrical conductance of discontinuous thin metal films. It is assumed that the islands are all the same size but that their gap lengths have a gaussian distribution. Voltages applied between two adjacent islands differ from island to island depending on the gap length. The highest voltage is between the two islands that have the longest gap length to keep the current density constant. The results of computations show that the voltage between these two islands can be about a hundred times higher than the average voltage calculated from the voltage between the two electrodes and that the logarithm of the conductance depends almost linearly on the square root of the voltage between the two electrodes above a threshold voltage. At the highest voltage the conductance tends to saturate.  相似文献   
29.
30.
Lacrimal ductal cysts are rare, especially in the orbit. A case of lacrimal ductal cyst in the orbital lobe, revealed by computed tomography and magnetic resonance imaging, is described in a 16-year-old man who was successfully treated by complete surgical excision. The radiologic and clinical features of this type of lacrimal ductal cyst are discussed.  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