全文获取类型
收费全文 | 501433篇 |
免费 | 6699篇 |
国内免费 | 1450篇 |
专业分类
电工技术 | 9219篇 |
综合类 | 480篇 |
化学工业 | 75697篇 |
金属工艺 | 20238篇 |
机械仪表 | 15396篇 |
建筑科学 | 12082篇 |
矿业工程 | 2712篇 |
能源动力 | 12105篇 |
轻工业 | 44227篇 |
水利工程 | 5244篇 |
石油天然气 | 9969篇 |
武器工业 | 83篇 |
无线电 | 59593篇 |
一般工业技术 | 97384篇 |
冶金工业 | 91837篇 |
原子能技术 | 11507篇 |
自动化技术 | 41809篇 |
出版年
2021年 | 3796篇 |
2019年 | 3660篇 |
2018年 | 6471篇 |
2017年 | 6479篇 |
2016年 | 6915篇 |
2015年 | 4444篇 |
2014年 | 7547篇 |
2013年 | 21546篇 |
2012年 | 12152篇 |
2011年 | 16497篇 |
2010年 | 13308篇 |
2009年 | 15062篇 |
2008年 | 15962篇 |
2007年 | 15787篇 |
2006年 | 14222篇 |
2005年 | 13148篇 |
2004年 | 12416篇 |
2003年 | 12118篇 |
2002年 | 11929篇 |
2001年 | 11785篇 |
2000年 | 11263篇 |
1999年 | 11381篇 |
1998年 | 26886篇 |
1997年 | 19619篇 |
1996年 | 15465篇 |
1995年 | 11908篇 |
1994年 | 10683篇 |
1993年 | 10525篇 |
1992年 | 8246篇 |
1991年 | 7861篇 |
1990年 | 7548篇 |
1989年 | 7443篇 |
1988年 | 7244篇 |
1987年 | 6253篇 |
1986年 | 6154篇 |
1985年 | 7205篇 |
1984年 | 6815篇 |
1983年 | 6140篇 |
1982年 | 5804篇 |
1981年 | 6045篇 |
1980年 | 5740篇 |
1979年 | 5503篇 |
1978年 | 5456篇 |
1977年 | 6346篇 |
1976年 | 8047篇 |
1975年 | 5024篇 |
1974年 | 4866篇 |
1973年 | 4915篇 |
1972年 | 4103篇 |
1971年 | 3854篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
151.
152.
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
153.
154.
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
155.
156.
Bican Osman Bayça Salih Uğur Kuleyin Hamdi Gümrük Recep 《Metal Science and Heat Treatment》2021,63(3-4):156-162
Metal Science and Heat Treatment - The effect of solid boronizing at 950°C for 2 and 4 h on the phase composition, microstructure, hardness and abrasive wear of steel AISI 304L is studied... 相似文献
157.
158.
159.
160.
D. Solís-Cortés E. Navarrete-Astorga J.L. Costa-Krämer J. Salguero-Fernandez R. Schrebler D. Leinen E.A. Dalchiele J.R. Ramos-Barrado F. Martín 《Ceramics International》2019,45(5):5577-5587
C-axis textured thin films of gallium-doped indium zinc oxide (GIZO) with a 2% ratio of Ga/Zn, were obtained via RF-magnetron sputtering with high transparency and electrical conductivity. A Box-Behnken response surface design was used to evaluate the effects of the deposition parameters (In2O3 target power, deposition time, and substrate temperature) on the chemical composition, optical, electrical, and structural properties of the GIZO films. The optical constants and the electrical properties were obtained using optical models. The GIZO stoichiometry, and therefore the In/Zn atomic ratio, affected the crystallinity, crystalline parameters, band gap, and charge carrier mobility of the GIZO films. The charge carrier density was related to the change in the crystalline parameters of the hexagonal structure and the In/Zn atomic ratio. The best electrical conductivity values (1.75?×?103 Ω?1 cm?1) were obtained for GIZO films with In/Zn ratio ≥?1. Several figures of merit (FOM) defined for the visible and solar regions were comparatively used to select the optimal In/Zn atomic ratio that provided the best balance between the conductivity and the transparency. The optimal In/Zn ratio was in a range of 0.85–0.90 for the GIZO films. 相似文献