全文获取类型
收费全文 | 1909篇 |
免费 | 98篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 18篇 |
综合类 | 3篇 |
化学工业 | 472篇 |
金属工艺 | 40篇 |
机械仪表 | 46篇 |
建筑科学 | 46篇 |
矿业工程 | 4篇 |
能源动力 | 58篇 |
轻工业 | 369篇 |
水利工程 | 12篇 |
石油天然气 | 4篇 |
无线电 | 158篇 |
一般工业技术 | 296篇 |
冶金工业 | 189篇 |
原子能技术 | 14篇 |
自动化技术 | 281篇 |
出版年
2023年 | 19篇 |
2022年 | 57篇 |
2021年 | 59篇 |
2020年 | 42篇 |
2019年 | 31篇 |
2018年 | 60篇 |
2017年 | 64篇 |
2016年 | 72篇 |
2015年 | 54篇 |
2014年 | 73篇 |
2013年 | 130篇 |
2012年 | 119篇 |
2011年 | 117篇 |
2010年 | 93篇 |
2009年 | 87篇 |
2008年 | 100篇 |
2007年 | 85篇 |
2006年 | 76篇 |
2005年 | 45篇 |
2004年 | 36篇 |
2003年 | 61篇 |
2002年 | 53篇 |
2001年 | 35篇 |
2000年 | 30篇 |
1999年 | 28篇 |
1998年 | 67篇 |
1997年 | 55篇 |
1996年 | 29篇 |
1995年 | 28篇 |
1994年 | 16篇 |
1993年 | 25篇 |
1992年 | 14篇 |
1991年 | 10篇 |
1990年 | 18篇 |
1989年 | 13篇 |
1988年 | 10篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1973年 | 5篇 |
1971年 | 3篇 |
1966年 | 4篇 |
排序方式: 共有2010条查询结果,搜索用时 0 毫秒
71.
Simonetta Tuti Franco Pepe Daniela Pietrogiacomi Valerio Indovina 《Catalysis Today》2002,75(1-4):373-378
FeOx/ZrO2 samples, prepared by impregnation with Fe(NO3)3, were characterised by means of DRS, XRD, FTIR, redox cycles and volumetric CO adsorption. Volumetric CO adsorption, combined with FTIR, showed that 45% of iron in the sample containing 2.8 Fe atoms nm−2 was capable of forming iron carbonyls. DRS evidenced Fe2O3 on samples with Fe-content≥2.8 atoms nm−2. The selective catalytic reduction of NO with C3H6 in the presence of O2 was studied with a reactant mixture containing NO=4000 ppm, C3H6=4000 ppm, O2=2%. The dependence on iron-content suggests that only isolated iron, prevailing in dilute FeOx/ZrO2, is active for NO reduction, whereas iron on the surface of small oxide particles, prevailing in concentrated FeOx/ZrO2, is active for C3H6 combustion. 相似文献
72.
Summary
The copolymerization of styrene with 1-alkene (1-hexene, 1-decene and 1-hexadecene) has been tested using combined diphenylzinc-additive
initiator systems, including diphenylzinc (Ph2Zn), a metallocene and methylaluminoxane (MAO). The metallocene were biscyclopentadienyltitanium dichloride, bis(n-butylcyclopentadienyl)titanium
dichloride, cyclopentadienyltitanium trichloride and bisindenylzirconium dichloride. For Ph2Zn-metallocene-MAO systems, titanocenes gave mainly syndiotactic homo polystyrene irrespective of the styrene/1-alkene proportion
in the initial feed. Systems including Ind2ZrCl2 were able to copolymerize styrene 1-alkene with the copolymers incorporating alkene in a lower proportion than the present
in the initial feed.
Keywords: Styrene copolymerization; diphenylzinc; metallocene catalysts; tacticity.
Received: 17 November 2000/Revised version: 9 May 2001/Accepted: 10 May 2001 相似文献
73.
Josefina Pérez-Arantegui Judit Molera Angel Larrea Trinitat Pradell Marius Vendrell-Saz Ilaria Borgia Brunetto G. Brunetti Franco Cariati Paola Fermo Marcello Mellini Antonio Sgamellotti Cecilia Viti 《Journal of the American Ceramic Society》2001,84(2):442-46
Luster is a decorative metallic film that was applied on the surface of medieval glazed pottery. It can be obtained via the low-temperature (∼650°C), controlled reduction of copper and silver compounds. In this paper, we show that luster is a thin layered film (200–500 nm thick) that contains metallic spherical nanocrystals dispersed in a silicon-rich matrix and has a metal-free outermost glassy layer that is 10–20 nm thick. Silver nanocrystals seem to be separated from those of copper, forming aggregates 5–100 μm in diameter. This composite structure exhibits optical properties that are dependent on both the particle size and the matrix. Luster is indeed the first reproducible nanostructured thin metallic film that was made by humans. 相似文献
74.
75.
Tim Helbing Caterina Carraro Alexander Francke Dr. Alice Sosic Michele De Franco Prof. Dr. Valentina Gandin Prof. Dr. Richard Göttlich Prof. Dr. Barbara Gatto 《ChemMedChem》2020,15(21):2040-2051
In this study, we describe the synthesis and biological evaluation of a set of bis-3-chloropiperidines (B−CePs) containing rigid aromatic linker structures. A modification of the synthetic strategy also enabled the synthesis of a pilot tris-3-chloropiperidine (Tri-CeP) bearing three reactive meta-chloropiperidine moieties on the aromatic scaffold. A structure–reactivity relationship analysis of B−CePs suggests that the arrangement of the reactive units affects the DNA alkylating activity, while also revealing correlations between the electron density of the aromatic system and the reactivity with biologically relevant nucleophiles, both on isolated DNA and in cancer cells. Interestingly, all aromatic 3-chloropiperidines exhibited a marked cytotoxicity and tropism for 2D and 3D cultures of pancreatic cancer cells. Therefore, the new aromatic 3-chloropiperidines appear to be promising contenders for further development of mustard-based anticancer agents aimed at pancreatic cancers. 相似文献
76.
77.
Rosana Fatima Galindo Luis Antonio Barbosa Cortez Telma Teixeira Franco 《化学工程与技术》2020,43(8):1530-1537
An alternative for reducing emissions from marine fuel is to blend bio-oil from lignocellulose non-edible feedstocks to diesel fossil fuels. Phase diagrams of the ternary systems were built to represent the transition from heterogeneous regions to homogeneous regions. Four homogeneous blends of bio-oil of eucalyptus-bioethanol-marine gasoil were experimentally characterized with respect to the most important fuel parameters for marine engines: water content, flash point, low heating value, viscosity, and acidity. Blends with closer properties to marine gasoil replacement, lower costs, and environmental impacts should be tested for large engines. 相似文献
78.
79.
80.
Antioxidant ability of potato (Solanum tuberosum) peel extracts to inhibit soybean oil oxidation 下载免费PDF全文