全文获取类型
收费全文 | 302465篇 |
免费 | 4517篇 |
国内免费 | 829篇 |
专业分类
电工技术 | 5116篇 |
综合类 | 173篇 |
化学工业 | 48626篇 |
金属工艺 | 12152篇 |
机械仪表 | 8888篇 |
建筑科学 | 7334篇 |
矿业工程 | 1872篇 |
能源动力 | 7017篇 |
轻工业 | 28793篇 |
水利工程 | 3352篇 |
石油天然气 | 7148篇 |
武器工业 | 18篇 |
无线电 | 32124篇 |
一般工业技术 | 59288篇 |
冶金工业 | 54675篇 |
原子能技术 | 7590篇 |
自动化技术 | 23645篇 |
出版年
2021年 | 2537篇 |
2019年 | 2379篇 |
2018年 | 4291篇 |
2017年 | 4237篇 |
2016年 | 4539篇 |
2015年 | 2950篇 |
2014年 | 4871篇 |
2013年 | 13235篇 |
2012年 | 7786篇 |
2011年 | 10050篇 |
2010年 | 8247篇 |
2009年 | 9317篇 |
2008年 | 9590篇 |
2007年 | 9443篇 |
2006年 | 8223篇 |
2005年 | 7633篇 |
2004年 | 7121篇 |
2003年 | 6864篇 |
2002年 | 6907篇 |
2001年 | 6679篇 |
2000年 | 6343篇 |
1999年 | 6454篇 |
1998年 | 15810篇 |
1997年 | 11685篇 |
1996年 | 8994篇 |
1995年 | 6750篇 |
1994年 | 6109篇 |
1993年 | 5999篇 |
1992年 | 4545篇 |
1991年 | 4510篇 |
1990年 | 4350篇 |
1989年 | 4366篇 |
1988年 | 4319篇 |
1987年 | 3652篇 |
1986年 | 3647篇 |
1985年 | 4224篇 |
1984年 | 4009篇 |
1983年 | 3650篇 |
1982年 | 3468篇 |
1981年 | 3612篇 |
1980年 | 3469篇 |
1979年 | 3387篇 |
1978年 | 3468篇 |
1977年 | 4002篇 |
1976年 | 5181篇 |
1975年 | 3168篇 |
1974年 | 3024篇 |
1973年 | 3035篇 |
1972年 | 2657篇 |
1971年 | 2474篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Simutin A. N. Deineko A. V. Zertsalov M. G. 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2021,55(4):482-486
Power Technology and Engineering - The monitoring of hydraulic structures as high-risk facilities is discussed. Monitoring should ensure the reliability and functioning of a hydraulic structure... 相似文献
102.
Chertkov Yu. B. Anikin M. N. Lebedev I. I. Naimushin A. G. Smol’nikov N. V. 《Atomic Energy》2021,131(1):42-45
Atomic Energy - The results of calculations and experimental determination of the neutronics characteristics of the IRT-T research reactor are presented. The IRT-T reactor is a pool reactor with... 相似文献
103.
G. Inglese 《Inverse Problems in Science & Engineering》2019,27(4):439-459
We deal with the mathematical model of the incremental degradation of the internal coating (e.g. a polymeric material) of a metallic pipe in which a fluid flows relatively fast. The fluid drags solid impurities so that longitudinal scratches, inaccessible to any direct inspection procedure, are produced on the coating. Time evolution of this kind of defects can be reconstructed from the knowledge of a sequence of temperature maps of the external surface. The time-varying orthogonal section of this damaged interface is determined as a function of time and polar angle through the identification of a suitable effective heat transfer coefficient by means of Thin Plate Approximation. 相似文献
104.
Byakova O. V. Stepanov G. V. Vlasov A. O. Danylyuk V. E. Semenov N. V. Berezovs’kyi O. M. Gnyloskurenko S. V. 《Strength of Materials》2019,51(5):726-734
Strength of Materials - The paper addresses the investigation of high-strain rate compressive behavior of Al foams subjected to impact at the intermediate striking velocity ranged from 40 to... 相似文献
105.
106.
Bram H. Frohock Jessica M. Gilbertie Dr. Jennifer C. Daiker Dr. Lauren V. Schnabel Dr. Joshua G. Pierce 《Chembiochem : a European journal of chemical biology》2020,21(7):933-937
The failure of frontline antibiotics in the clinic is one of the most serious threats to human health and requires a multitude of novel therapeutics and innovative approaches to treatment so as to curtail the growing crisis. In addition to traditional resistance mechanisms resulting in the lack of efficacy of many antibiotics, most chronic and recurring infections are further made tolerant to antibiotic action by the presence of biofilms. Herein, we report an expanded set of 5-benzylidene-4-oxazolidinones that are able to inhibit the formation of Staphylococcus aureus biofilms, disperse preformed biofilms, and, in combination with common antibiotics, are able to significantly reduce the bacterial load in a robust collagen-matrix model of biofilm infection. 相似文献
107.
Lorena Rodríguez-López Myriam Rincón-Fontán Xanel Vecino Ana B. Moldes Jose M. Cruz 《Journal of surfactants and detergents》2020,23(1):79-90
Over the last few years, the global biosurfactant market has raised due to the increasing awareness among consumers, for the use of biological or bio-based products. Because of their composition, it can be speculated that these are more biocompatible and more biodegradable than their chemical homologous. However, at the moment, no studies exist in the literature about the biodegradability of biosurfactants. In this work, a biosurfactant contained in a crude extract, obtained from a corn wet-milling industry stream that ferments spontaneously in the presence of lactic acid bacteria, was subjected to a biodegradation study, without addition of external microbial biomass, under different conditions of temperature (5–45 °C), biodegradation time (15–55 days), and pH (5–7). For that, a Box–Behnken factorial design was applied, which allowed to predict the percentage of biodegradation for the biosurfactant contained in the crude extract, between the range of the independent variables selected in the study, obtaining biodegradation values between 3 and 80%. The percentage of biodegradation for the biosurfactant was calculated based on the increase in the surface tension of samples of the crude extract. Furthermore, it was also possible to predict the variation in t1/2 for the biosurfactant (time to achieve the 50% of biodegradation) under different conditions. 相似文献
108.
109.
E. G. Kulapina N. M. Makarova O. I. Kulapina I. A. Utc V. V. Baraguzina 《Petroleum Chemistry》2015,55(10):892-900
Potentiometric sensors with plasticized poly(vinyl chloride) membranes based on β-lactam–tetraalkylammonium ion associates sensitive to penicillin antibiotics are proposed. The physicochemical characteristics (solubility product constants and dissociation constants) of active membrane components and the electrode, transport, and selective properties of the membranes of liquidand solid-contact sensors have been studied. The quantitative characteristics of membrane transport (penetrability, ion flux, and transport rate) have been evaluated. The main charge carriers in the membranes and at the membrane/solution interface have been determined from the membrane transport characteristics. The potentiometric sensors are shown to be applicable to the determination of penicillin antibiotics in biological fluids (blood serum and oral fluid) from patients with urinary tract infection. 相似文献
110.