全文获取类型
收费全文 | 4096篇 |
免费 | 132篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 32篇 |
综合类 | 5篇 |
化学工业 | 909篇 |
金属工艺 | 53篇 |
机械仪表 | 73篇 |
建筑科学 | 116篇 |
矿业工程 | 9篇 |
能源动力 | 93篇 |
轻工业 | 295篇 |
水利工程 | 23篇 |
石油天然气 | 20篇 |
无线电 | 273篇 |
一般工业技术 | 586篇 |
冶金工业 | 1254篇 |
原子能技术 | 27篇 |
自动化技术 | 461篇 |
出版年
2023年 | 38篇 |
2022年 | 88篇 |
2021年 | 135篇 |
2020年 | 73篇 |
2019年 | 76篇 |
2018年 | 67篇 |
2017年 | 74篇 |
2016年 | 57篇 |
2015年 | 79篇 |
2014年 | 86篇 |
2013年 | 149篇 |
2012年 | 145篇 |
2011年 | 165篇 |
2010年 | 138篇 |
2009年 | 130篇 |
2008年 | 161篇 |
2007年 | 146篇 |
2006年 | 126篇 |
2005年 | 93篇 |
2004年 | 96篇 |
2003年 | 101篇 |
2002年 | 73篇 |
2001年 | 83篇 |
2000年 | 68篇 |
1999年 | 74篇 |
1998年 | 275篇 |
1997年 | 169篇 |
1996年 | 155篇 |
1995年 | 105篇 |
1994年 | 96篇 |
1993年 | 75篇 |
1992年 | 37篇 |
1991年 | 48篇 |
1990年 | 43篇 |
1989年 | 45篇 |
1988年 | 54篇 |
1987年 | 39篇 |
1986年 | 29篇 |
1985年 | 57篇 |
1984年 | 36篇 |
1983年 | 27篇 |
1982年 | 36篇 |
1981年 | 32篇 |
1980年 | 20篇 |
1979年 | 24篇 |
1978年 | 24篇 |
1977年 | 42篇 |
1976年 | 55篇 |
1974年 | 22篇 |
1973年 | 19篇 |
排序方式: 共有4229条查询结果,搜索用时 0 毫秒
151.
Inside Cover: Tetrazolylhydrazides as Selective Fragment‐Like Inhibitors of the JumonjiC‐Domain‐Containing Histone Demethylase KDM4A (ChemMedChem 11/2015) 下载免费PDF全文
152.
Preparation and Reinforcement of Dual‐Porous Biocompatible Cellulose Scaffolds for Tissue Engineering 下载免费PDF全文
Nicole Pircher David Fischhuber Leticia Carbajal Christine Strauß Jean‐Marie Nedelec Cornelia Kasper Thomas Rosenau Falk Liebner 《大分子材料与工程》2015,300(9):911-924
Biocompatible cellulose‐based aerogels composed of nanoporous struts, which embed interconnected voids of controlled micron‐size, have been prepared employing temporary templates of fused porogens, reinforcement by interpenetrating PMMA networks and supercritical carbon dioxide drying. Different combinations of cellulose solvent (Ca(SCN)2/H2O/LiCl or [EMIm][OAc]/DMSO) and anti‐solvent (EtOH), porogen type (paraffin wax or PMMA spheres) and porogen size (various fractions in the range of 100–500 μm) as well as intensity of PMMA reinforcement have been investigated to tailor the materials for cell scaffolding applications. All aerogels exhibited an open and dual porosity (micronporosity >100 μm and nanoporosity extending to the low micrometer range). Mechanical properties of the dual‐porous aerogels under compressive stress were considerably improved by introduction of interpenetrating PMMA networks. The effect of the reinforcing polymer on attachment, spreading, and proliferation of NIH 3T3 fibroblast cells, cultivated on selected dual‐porous aerogels to pre‐evaluate their biocompatibility was similarly positive. 相似文献
153.
Water-borne two-pack coatings based on a novel epoxy resin emulsion, cross-linked with three different amine group containing curing agents, are discussed. The aqueous binders developed at the Research Laboratory at Dow Deutschland Inc. are free of volatile organic content. The epoxy resin emulsion has a low MFFT (minimum film formation temperature) and is hence capable of forming a continuous film at low temperatures and good emulsifying properties. The interaction is discussed between the epoxy emulsion, pigments and hardeners which are in aqueous solution, emulsion or hydrophobic (non-aqueous) form. Some of the described systems will gain interest in a wide range of applications because of their excellent properties, including adhesion to various substrates, resistance to chemicals, solvents and water, hardness and toughness. The predicted major applications for such systems include concrete, plastic and wood coatings, and anti-corrosive systems for steel and other metals. 相似文献
154.
M. El Moussaouiti R. Boistelle A. Bouhaouss J.P. Klein 《Chemical engineering journal (Lausanne, Switzerland : 1996)》1997,68(2-3)
We aim to show the existence of agglomeration by measuring and modelling secondary nucleation and crystal growth rates of calcium sulphate hemihydrate, CaSO4-0.5 H2O, in concentrated phosphoric acid solutions. Using a batch crystallizer we measured the evolution of the population density as a function of supersaturation, H2SO4 excess and stirring rates. All experiments were carried out at 90 °C in solutions at 40 wt.% of P2O5, simulating the usual conditions for crystallizing hemihydrate in the industrial processes of phosphoric acid production. Nucleation and growth rates were calculated from the population number densities, using the moments analysis method. A model is presented for describing the crystallization process of hemihydrate. It is shown that secondary nucleation and growth rates are quadratic functions of supersaturation. H2SO4 concentrations affect supersaturation but at the same supersaturation the growth rates are not significantly different. Nucleation is independent of the stirring rate, whereas growth rates are slightly affected for stirring rates up to 500 rpm. Taking agglomeration into account, the moments method fits very well the experimental data. 相似文献
155.
Julie K. Furmick Dr. Ichiro Kaneko Angela N. Walsh Joanna Yang Jaskaran S. Bhogal Geoffrey M. Gray Juan C. Baso Drew O. Browder Jessica L. S. Prentice Luis A. Montano Chanh C. Huynh Lisa M. Marcus Dorian G. Tsosie Jungeun S. Kwon Alexis Quezada Nicole M. Reyes Brittney Lemming Puneet Saini Dr. Arjan van der Vaart Dr. Thomas L. Groy Dr. Pamela A. Marshall Dr. Peter W. Jurutka Dr. Carl E. Wagner 《ChemMedChem》2012,7(9):1551-1566
156.
Dense and homogeneous multi-walled carbon nanotube/metal composites are prepared by powder metallurgy. The distribution of the nano-reinforcements in the matrix is studied by scanning electron microscopy and Raman spectroscopy. The mechanical properties of the composites are determined by means of static tensile tests and Vickers micro-hardness measurements. We show that a homogeneous dispersion of the nanotubes at the micron scale is required in order to improve the mechanical properties of the metal matrix composite. This can be achieved using ball-milling through the mechanisms of plastic deformation and cold-welding. Accordingly, we report significant improvements to the mechanical properties of composites prepared with a high-performance aluminium alloy AA5083 matrix. 相似文献
157.
Nayara S. Klein Jörg Bachmann Antonio Aguado Berenice Toralles-Carbonari 《Cement and Concrete Research》2012,42(12):1611-1620
The wettability of granular materials has a direct effect on the workability of pastes, mortars and concretes containing such materials. Given this, the wetting behaviour of two Portland cements, two mineral admixtures (limestone filler and silica fume) and different sand types (siliceous, limestone and granite) was evaluated through the measurement of the contact angle between these materials and water. The results show that all the materials possess high wettability. A chemical agent, dichlorodimethylsilane, was used to modify the surface properties of a 0–1 mm siliceous sand, making it more hydrophobic and, therefore, unable to be spontaneously wetted by water. The properties of a mortar produced with the silane-treated sand were evaluated, showing improvements on workability as a result of the chemical treatment. 相似文献
158.
Vinícius L. Carvalho Camila Safieddine Nicole R. Demarquette Luís A. Pinheiro 《应用聚合物科学杂志》2020,137(3):48295
The Friedel–Crafts alkylation reaction has been applied to reactively compatibilize a ternary blend of high-density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS). The reactions were carried out in an internal mixer using varying catalyst concentrations. The resulting compatibilizer was quantified after Soxhlet extraction. In addition, p-substitution due to the grafting of alkyl groups onto the PS benzene ring was identified via nuclear magnetic resonance spectroscopy. The size of the PS domain in the reactive compositions is decreased by 80%. Moreover, the phase in which PS droplets were dispersed varied, that is, in the nonreactive blends they were found in the PP phase and in the reactive blends they shifted toward the HDPE phase. The effect of the compatibilizing agent was to improve the mechanical properties of the blend. Even with the lowest catalyst content, the properties of elongation-at-break, tensile strength, toughness, and elastic modulus showed improvements. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48295. 相似文献
159.
Marwa Sta Graziele Aguiar Abilio A. J. Forni Simone F. Medeiros Amilton M. Santos Nicole R. Demarquette 《应用聚合物科学杂志》2020,137(11):48472
In this work, nanofiber scaffolds for surface drug delivery applications were obtained by electrospinning poly(N-vinylcaprolactam) (PNVCL) and its blends with poly(ε-caprolactone) and poly(N-vinylcaprolactam)-b-poly(ε-caprolactone). The process parameters to obtain smooth and beadless PNVCL fibers were optimized. The average fibers diameter was less than 1 μm, and it was determined by scanning electron microscopy analyses. Their affinity toward water was evaluated by measuring the contact angle with water. The ketoprofen release behavior from the fibers was analyzed using independent and model-dependent approaches. The low values of the release exponent (n < 0.5) obtained for 20 and 42 °C, indicating a Fickian diffusion mechanism for all formulations. Dissolution efficiencies (DEs) revealed the effect of polymer composition, methodology used in the electrospinning process, and temperature on the release rate of ketoprofen. PNVCL/poly(N-vinylcaprolactam)-b-poly(ε-caprolactone)-based nanofibers showed greater ability to control the in vitro release of ketoprofen, in view of reduced kinetic constant and DE, making this material promising system for controlling release of hydrophobic drugs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48472. 相似文献
160.