全文获取类型
收费全文 | 2172篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 15篇 |
金属工艺 | 2篇 |
机械仪表 | 39篇 |
建筑科学 | 6篇 |
能源动力 | 5篇 |
轻工业 | 52篇 |
水利工程 | 1篇 |
无线电 | 15篇 |
一般工业技术 | 7篇 |
冶金工业 | 2016篇 |
自动化技术 | 12篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 7篇 |
2012年 | 2篇 |
2011年 | 5篇 |
2010年 | 7篇 |
2009年 | 9篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 3篇 |
2003年 | 7篇 |
2002年 | 9篇 |
2001年 | 8篇 |
2000年 | 18篇 |
1999年 | 75篇 |
1998年 | 607篇 |
1997年 | 356篇 |
1996年 | 223篇 |
1995年 | 140篇 |
1994年 | 99篇 |
1993年 | 119篇 |
1992年 | 12篇 |
1991年 | 18篇 |
1990年 | 15篇 |
1989年 | 17篇 |
1988年 | 23篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 17篇 |
1984年 | 1篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 19篇 |
1980年 | 27篇 |
1978年 | 6篇 |
1977年 | 66篇 |
1976年 | 160篇 |
1975年 | 4篇 |
1973年 | 1篇 |
1964年 | 1篇 |
1955年 | 3篇 |
排序方式: 共有2174条查询结果,搜索用时 15 毫秒
81.
AG Baranovskii TG Kanyshkova AS Mogelnitskii VA Naumov VN Buneva EI Gusev AN Boiko TA Zargarova OO Favorova GA Nevinsky 《Canadian Metallurgical Quarterly》1998,63(11):1239-1248
It is known that in the blood of patients with some autoimmune diseases catalytically active antibodies hydrolyzing proteins, DNA, and RNA may be detected. In the present work homogeneous preparations of IgG antibodies (Ab) possessing high affinity for nucleic acids (NA) were obtained for the first time from blood and cerebrospinal fluid of patients with multiple sclerosis (MS). The fraction of IgG Ab as well as its Fab fragments and isolated light chains of both kappa- and lambda-types were shown to catalyze effectively the hydrolysis of DNA and RNA. It is shown by different methods that the capability for nucleic acid hydrolysis is an intrinsic property of the polyclonal Ab. NA-hydrolyzing Ab were detected in the blood of 69 of 72 and in the cerebrospinal fluid of 5 of 5 examined MS patients, while they were not detected in the blood of any of 50 healthy donors examined. Comparison of relative rates of RNA hydrolysis and of the substrate specificity in hydrolysis of various model RNAs--cCMP, poly(U), poly(A), and poly(C)--revealed pronounced differences of MS antibodies from ribonucleases of human blood, ribonuclease A, and all earlier described abzymes. The abzymes are usually characterized by relatively low specific activities in comparison with that of normal enzymes catalyzing analogous reactions. Ab from the blood of MS patients are the first example of autoabzymes whose specific activity in RNA hydrolysis is comparable or even higher than that of pancreatic ribonuclease A--one of the most active RNA-hydrolyzing enzymes. 相似文献
82.
Four Trypanosoma evansi stocks with sensitivity to suramin in mice ranging from 0.05 to 160 mg kg-1 were cloned and sub-cloned and the sensitivity of the clones determined. The results suggest that it is easier to clone and sub-clone trypanosome stocks which are sensitive to suramin than those that are resistant to the action of the drug. The clones obtained from the four stocks had sensitivities to suramin which were similar to or different from the parent stocks. These results are important in view of the development of resistance for, in the presence of suramin, these resistant yet heterogeneous populations would provide the material from which selective processes could operate. These observations also suggest that the maintenance and spread of suramin-resistant trypanosomes might be curtailed by their comparative inability to establish themselves in a new host. 相似文献
83.
The chemical composition of yeast cells of Oidiodendron kalrai was analyzed and is expressed as percent dry weight. Cultures were grown in tryptone broth and in a liquid synthetic medium containing ammonium salts as a nitrogen source. After 48 h, carbohydrate levels were higher in the synthetic medium, but lipid levels were lower, Deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein contents did not differ significantly in the two media. The chemical components were also studied at different stages of growth. DNA remained relatively constant, but other components varied with the age of culture. The RNA was 6.6% at 18 h and declined rapidly to 5% by 24 h and remained constant, An initial protein content of 23% at 18 h increased rapidly to 37% by 48 h and gradually declined to 30% by day 10. The lipid content of 33% at 18 h decreased over the entire growth period to 10% by day 10. An initial carbohydrate level of 30% increased to a maximum of 54% by day 5 and then declined. 相似文献
84.
D Allasia C Angelini A Baldini L Bertanza V Bisi F Bobisut T Bolognese A Borg E Calimani P Capiluppi S Ciampolillo J Derkaoui ML Faccini-Turluer R Fantechi V Flaminio AG Frodesen D Gamba G Giacomelli H Huzita B Jongejans M Loreti C Louedec G Mandrioli A Margiotta A Marzari-Chiesa R Pazzi L Ramello L Riccati A Romero AM Rossi A Sconza P Serra-Lugaresi A Tenner Van Apeldoorn GW Van Dam P D Vignaud R Wigmans 《Canadian Metallurgical Quarterly》1985,31(11):2996-2998
85.
86.
87.
AG Rakhlenko 《Canadian Metallurgical Quarterly》1980,90(11):620-622
The efficacy of conduction anesthesia with 2% solutions of novocain, celnovocain, trimecain, lidocain during the preparation of teeth for metal crowns was studied in experiments on 16 dogs by neurohistological and histochemical examination of the Gasserian and superior cervical ganglions, the nodose ganglion, teeth and pericoronal tissues. It was established that in terms of the degree of anesthesia efficacy increase, the test anesthetics can be arranged as follows: novocain, celnovocain, trimecain, lidocain. 相似文献
88.
Effects of leukotriene D on the airways in asthma 总被引:2,自引:0,他引:2
M Griffin JW Weiss AG Leitch ER McFadden EJ Corey KF Austen JM Drazen 《Canadian Metallurgical Quarterly》1983,308(8):436-439
89.
Stefano Binetti Svetlana Chemiakina Roberto Sabella 《Photonic Network Communications》2001,3(3):237-243
The rapidly increasing data traffic volumes will demand for very high transmission capacity and network nodes throughput. Wavelength division multiplexing (WDM) technology will be asked to support many channels on the same fiber, both in point-to-point links and in WDM optical networks. The transmission of a high number of wavelength channels in all these systems is a key issue. This paper analyzes this topic, in both high capacity links and optical networks, highlighting the impact of fiber non-linearity, and addressing the main source of impairments. This is done through the use of a semi-analytical model recently upgraded to account for all the contributions deriving from Kerr effects, particularly four-wave mixing and cross-phase modulation. The analysis reveals that more than one hundred of channels at 2.5 Gbit/s can be transmitted in point-to-point links whose length can span until the order of 1000 km, and 32 channels per fiber, at the previous bit rate, can be handled in WDM networks, without dispersion compensation. For a higher number of channels (e.g., 64) dispersion compensation is needed. 相似文献
90.
A G protein gamma subunit-like domain shared between RGS11 and other RGS proteins specifies binding to Gbeta5 subunits 总被引:1,自引:0,他引:1
BE Snow AM Krumins GM Brothers SF Lee MA Wall S Chung J Mangion S Arya AG Gilman DP Siderovski 《Canadian Metallurgical Quarterly》1998,95(22):13307-13312
Regulators of G protein signaling (RGS) proteins act as GTPase-activating proteins (GAPs) toward the alpha subunits of heterotrimeric, signal-transducing G proteins. RGS11 contains a G protein gamma subunit-like (GGL) domain between its Dishevelled/Egl-10/Pleckstrin and RGS domains. GGL domains are also found in RGS6, RGS7, RGS9, and the Caenorhabditis elegans protein EGL-10. Coexpression of RGS11 with different Gbeta subunits reveals specific interaction between RGS11 and Gbeta5. The expression of mRNA for RGS11 and Gbeta5 in human tissues overlaps. The Gbeta5/RGS11 heterodimer acts as a GAP on Galphao, apparently selectively. RGS proteins that contain GGL domains appear to act as GAPs for Galpha proteins and form complexes with specific Gbeta subunits, adding to the combinatorial complexity of G protein-mediated signaling pathways. 相似文献