全文获取类型
收费全文 | 264596篇 |
免费 | 3982篇 |
国内免费 | 910篇 |
专业分类
电工技术 | 5308篇 |
综合类 | 516篇 |
化学工业 | 36918篇 |
金属工艺 | 10490篇 |
机械仪表 | 8704篇 |
建筑科学 | 6174篇 |
矿业工程 | 1175篇 |
能源动力 | 6636篇 |
轻工业 | 22986篇 |
水利工程 | 2639篇 |
石油天然气 | 4033篇 |
武器工业 | 84篇 |
无线电 | 35611篇 |
一般工业技术 | 51394篇 |
冶金工业 | 47559篇 |
原子能技术 | 5509篇 |
自动化技术 | 23752篇 |
出版年
2021年 | 2190篇 |
2019年 | 2184篇 |
2018年 | 3725篇 |
2017年 | 3728篇 |
2016年 | 3948篇 |
2015年 | 2528篇 |
2014年 | 4296篇 |
2013年 | 11845篇 |
2012年 | 6928篇 |
2011年 | 9321篇 |
2010年 | 7350篇 |
2009年 | 8224篇 |
2008年 | 9013篇 |
2007年 | 8917篇 |
2006年 | 8097篇 |
2005年 | 7390篇 |
2004年 | 7104篇 |
2003年 | 6847篇 |
2002年 | 6241篇 |
2001年 | 6253篇 |
2000年 | 5887篇 |
1999年 | 6073篇 |
1998年 | 14223篇 |
1997年 | 10214篇 |
1996年 | 8005篇 |
1995年 | 6526篇 |
1994年 | 5824篇 |
1993年 | 5689篇 |
1992年 | 4626篇 |
1991年 | 4285篇 |
1990年 | 4118篇 |
1989年 | 3832篇 |
1988年 | 3676篇 |
1987年 | 3224篇 |
1986年 | 3114篇 |
1985年 | 3681篇 |
1984年 | 3452篇 |
1983年 | 3097篇 |
1982年 | 2898篇 |
1981年 | 2990篇 |
1980年 | 2804篇 |
1979年 | 2697篇 |
1978年 | 2539篇 |
1977年 | 2964篇 |
1976年 | 3584篇 |
1975年 | 2346篇 |
1974年 | 2343篇 |
1973年 | 2326篇 |
1972年 | 1857篇 |
1971年 | 1747篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
91.
Christopher J. Marvel Qirong Yang Scott D. Walck Kelvin Y. Xie Kristopher D. Behler Jerry C. LaSalvia Masashi Watanabe Richard A. Haber Martin P. Harmer 《Journal of the American Ceramic Society》2022,105(5):2990-3007
Compositional analysis of boron carbide on nanometer length scales to examine or interpret atomic mechanisms, for example, solid-state amorphization or grain-boundary segregation, is challenging. This work reviews advancements in high-resolution microanalysis to characterize multiple generations of boron carbide. First, ζ-factor microanalysis will be introduced as a powerful (scanning) transmission electron microscopy ((S)TEM) analytical framework to accurately characterize boron carbide. Three case studies involving the application of ζ-factor microanalysis will then be presented: (1) accurate stoichiometry determination of B-doped boron carbide using ζ-factor microanalysis and electron energy loss spectroscopy, (2) normalized quantification of silicon grain-boundary segregation in Si-doped boron carbide, and (3) calibration of a scanning electron microscope X-ray energy-dispersive spectroscopy (XEDS) system to measure compositional homogeneity differences of B/Si-doped arc-melted boron carbides in the as-melted and annealed conditions. Overall, the improvement and application of advanced analytical tools have helped better understand processing–microstructure–property relationships and successfully manufacture high-performance ceramics. 相似文献
92.
Dr. Markella Konstantinidou Asmaa Oun Pragya Pathak Bidong Zhang Zefeng Wang Frans ter Brake Dr. Amalia M. Dolga Dr. Arjan Kortholt Dr. Alexander Dömling 《ChemMedChem》2021,16(6):959-965
Here we present the rational design and synthetic methodologies towards proteolysis-targeting chimeras (PROTACs) for the recently-emerged target leucine-rich repeat kinase 2 (LRRK2). Two highly potent, selective, brain-penetrating kinase inhibitors were selected, and their structure was appropriately modified to assemble a cereblon-targeting PROTAC. Biological data show strong kinase inhibition and the ability of the synthesized compounds to enter the cells. However, data regarding the degradation of the target protein are inconclusive. The reasons for the inefficient degradation of the target are further discussed. 相似文献
93.
Dr. Walter D. Guerra Dr. Daniel Lucena-Agell Rafael Hortigüela Prof. Roberto A. Rossi Dr. J. Fernando Díaz Prof. José M. Padrón Dr. Silvia M. Barolo 《ChemMedChem》2021,16(19):3003-3016
We prepared a series of free NH and N-substituted dibenzonthiazines with potential anti-tumor activity from N-aryl-benzenesulfonamides. A biological test of synthesized compounds (59 samples) was performed in vitro measuring their antiproliferative activity against a panel of six human solid tumor cell lines and its tubulin inhibitory activity. We identified 6-(phenylsulfonyl)-6H-dibenzo[c,e][1,2]thiazine 5,5-dioxide and 6-tosyl-6H-dibenzo[c,e][1,2]thiazine 5,5-dioxide as the best compounds with promising values of activity (overall range of 2–5.4 μM). Herein, we report the dibenzothiazine core as a novel building block with antiproliferative activity, targeting tubulin dynamics. 相似文献
94.
Raul D. Rodriguez Sergey Shchadenko Gennadiy Murastov Anna Lipovka Maxim Fatkullin Ilia Petrov Tuan-Hoang Tran Alimzhan Khalelov Muhammad Saqib Nelson E. Villa Vladimir Bogoslovskiy Yan Wang Chang-Gang Hu Alexey Zinovyev Wenbo Sheng Jin-Ju Chen Ihsan Amin Evgeniya Sheremet 《Advanced functional materials》2021,31(17):2008818
Polyethylene terephthalate (PET) is the most widely used polymer in the world. For the first time, the laser-driven integration of aluminum nanoparticles (Al NPs) into PET to realize a laser-induced graphene/Al NPs/polymer composite, which demonstrates excellent toughness and high electrical conductivity with the formation of aluminum carbide into the polymer is shown. The conductive structures show an impressive mechanical resistance against >10000 bending cycles, projectile impact, hammering, abrasion, and structural and chemical stability when in contact with different solvents (ethanol, water, and aqueous electrolytes). Devices including thermal heaters, carbon electrodes for energy storage, electrochemical and bending sensors show this technology's practical application for ultra-robust polymer electronics. This laser-based technology can be extended to integrating other nanomaterials and create hybrid graphene-based structures with excellent properties in a wide range of flexible electronics’ applications. 相似文献
95.
Mishchenko S. E. Shatskii V. V. Litvinov A. V. Eliseev D. Yu. 《Journal of Communications Technology and Electronics》2021,66(4):412-419
Journal of Communications Technology and Electronics - The method for the constructive synthesis of planar antenna arrays (AAs) based on the neural network approach with consideration of... 相似文献
96.
97.
Volkovich A. G. Kolyadin V. I. Lemus A. V. Pavlenko V. I. Potapov V. N. Semenov S. G. Simirskii Yu. N. Chesnokov A. V. Shisha A. D. 《Atomic Energy》2021,129(6):349-355
Atomic Energy - The results of the dismantling of the active drain system and the decontamination of technological enclosures of the loop installations of the MR reactor, which is being... 相似文献
98.
D. Kherifi H. Belhouchet S. Ramesh K.Y. Sara Lee A. Kenzour S. Djoualah M.K.G. Abbas Y.H. Wong S. Ramesh 《Ceramics International》2021,47(12):16483-16490
In this work, the sintering behaviour of fluorapatite (FAp)–silicate composites prepared by mixing variable amounts of natural quartz (2.5 wt% to 20 wt%) and FAp was studied. The composites were pressureless sintered in air at temperatures from 1000 °C to 1350 °C. The effects of temperatures on the densification, phase formation, chemical bonding and Vickers hardness of the composites were evaluated. All the samples exhibited mixed phase, comprising FAp and francolite as the major constituents along with some minor phases of cristobalite, wollastonite, dicalcium silicate and/or whitlockite dependent on the quartz content and sintering temperature. The composite containing 2.5 wt% quartz exhibited the best sintering properties. The highest bulk density of 3 g/cm3 and a Vickers hardness of >4.2 GPa were obtained for the 2.5 wt% quartz–FAp composite when sintered at 1100 °C. The addition of quartz was found to alter the microstructure of the composites, where it exhibited a rod-like morphology when sintered at 1000 °C and a regular rounded grain structure when sintered at 1350 °C. A wetted grain surface was observed for composites containing high quartz content and was believed to be associated with a transient liquid phase sintering. 相似文献
99.
Jagadeesh Babu Sriramoju Murthy Muniyappa Navya Rani Marilingaiah Chetana Sabbanahalli Manjunath Shetty Ravi Mudike Chitrabanu C.P Prasanna D. Shivaramu Nagaraju G Kanchugarakoppal S. Rangappa Ananda Kumar C.S Dinesh Rangappa 《Ceramics International》2021,47(7):10314-10321
Application of brown titanium dioxide (TiO2-x) and its modified composite forms in the photocatalytic decomposition of organic pollutants in the environment is a promising way to provide solutions for environmental redemption. Herein, we report the synthesis of effective and stable TiO2-x nanoparticles with g-C3N4, RGO, and multiwalled carbon nanotubes (CNTs) using a simple hydrothermal method. Among all the as-synthesized samples, excellent photocatalytic degradation activity was observed for RGO-TiO2-x nanocomposite with high rate constants of 0.075 min?1, 0.083 min?1 and 0.093 min?1 for methylene blue, rhodamine-B, and rosebengal dyes under UV–Visible light irradiation, respectively. The altered bandgap (1.8 eV) and the large surface area of RGO-TiO2-x nanocomposite impacts on both absorption of visible light and efficiency of photogenerated charge electron (e?)/hole (h+) pair separation. This resulted in enhanced photocatalytic property of carbon-based TiO2-x nanocomposites. A systematic study on the influence of different carbon nanostructures on the photocatalytic activity of brown TiO2-x is carried out. 相似文献
100.
Kurdyukov A. P. Andrianova O. G. Belov A. A. Gol’din D. A. 《Automation and Remote Control》2021,82(4):565-618
Automation and Remote Control - In this survey, we discuss various approaches to control theory that have arisen in the recent decades and reflect the desire to reach a trade-off between the $$LQG... 相似文献