全文获取类型
收费全文 | 8810篇 |
免费 | 477篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 118篇 |
综合类 | 38篇 |
化学工业 | 2293篇 |
金属工艺 | 226篇 |
机械仪表 | 185篇 |
建筑科学 | 603篇 |
矿业工程 | 20篇 |
能源动力 | 281篇 |
轻工业 | 845篇 |
水利工程 | 87篇 |
石油天然气 | 44篇 |
武器工业 | 1篇 |
无线电 | 658篇 |
一般工业技术 | 1455篇 |
冶金工业 | 565篇 |
原子能技术 | 58篇 |
自动化技术 | 1821篇 |
出版年
2023年 | 85篇 |
2022年 | 202篇 |
2021年 | 336篇 |
2020年 | 184篇 |
2019年 | 203篇 |
2018年 | 271篇 |
2017年 | 235篇 |
2016年 | 317篇 |
2015年 | 235篇 |
2014年 | 338篇 |
2013年 | 627篇 |
2012年 | 482篇 |
2011年 | 618篇 |
2010年 | 428篇 |
2009年 | 492篇 |
2008年 | 455篇 |
2007年 | 413篇 |
2006年 | 342篇 |
2005年 | 294篇 |
2004年 | 269篇 |
2003年 | 260篇 |
2002年 | 194篇 |
2001年 | 140篇 |
2000年 | 139篇 |
1999年 | 115篇 |
1998年 | 130篇 |
1997年 | 133篇 |
1996年 | 101篇 |
1995年 | 81篇 |
1994年 | 80篇 |
1993年 | 85篇 |
1992年 | 62篇 |
1991年 | 60篇 |
1990年 | 61篇 |
1989年 | 68篇 |
1988年 | 50篇 |
1987年 | 47篇 |
1986年 | 50篇 |
1985年 | 54篇 |
1984年 | 63篇 |
1983年 | 46篇 |
1982年 | 38篇 |
1981年 | 39篇 |
1980年 | 40篇 |
1979年 | 32篇 |
1978年 | 35篇 |
1977年 | 34篇 |
1976年 | 40篇 |
1975年 | 42篇 |
1973年 | 36篇 |
排序方式: 共有9298条查询结果,搜索用时 31 毫秒
121.
Peter Van Puyvelde Sachin Velankar Jan Mewis Paula Moldenaers K. U. Leuven 《Polymer Engineering and Science》2002,42(10):1956-1964
The effect of physical compatibilization on the deformation and coalescence of droplets in immiscible polymer blends is discussed. Evidence is provided for the existence of concentration gradients in block copolymers along the interface during deformation. This causes complex changes in droplet shapes during deformation and relaxation. These concentration gradients also result in Marangoni stresses, which stabilize the droplets against deformation and breakup. Coalescence experiments have been performed, varying both the compatibilizer concentration and the shear rate. Existing coalescence models have been evaluated. An empirical extension of Chesters' partially mobile interface model is presented, that treats the effects of Marangoni stresses on the coalescence process as a higher effective viscosity ratio. 相似文献
122.
Preparation of polyesteramides-poly[(ε-caprolactam)-co-(ε-caprolactone)]s by anionic polymerization of ε-caprolactam in the presence of poly(ε-caprolactone) at 150 °C was studied in this paper. ε-Caprolactam magnesium bromide was used as an initiator of polymerization and polymeric materials containing 5-25 wt% ε-caprolactone units were obtained. Thermal methods (DSC and DMA) were employed for characterization of poly[(ε-caprolactam)-co-(ε-caprolactone)]s and their mechanical properties were also evaluated. By introducing the activator with N-acyllactam structure, the polymerization rate increased and it was possible to carry out the polymerization at 110 °C. Mechanical properties of polyesteramides were influenced by both the content of ε-caprolactone units incorporated into copolymer and polymerization temperature. The mechanism of incorporation of poly(ε-caprolactone) is discussed. The results show that it is not possible to restrict exchange transacylation reactions, progressing in the course of polymerization, by kinetic tools. 相似文献
123.
Johannes G. A. Terlingen Gijsbert A. J. Takens Frederik J. Van Der Gaag Allan S. Hoffman Jan Feijen 《应用聚合物科学杂志》1994,52(1):39-53
Poly(acrylic acid) (PAAc) films were treated with either an argon or a tetrafluoromethane (CF4) plasma and subsequently analyzed with X-ray photoelectron spectroscopy (XPS). PAAc films were decarboxylated during both types of plasma treatments. In addition, during the CF4 plasma treatment, the PAAc films became fluorinated. The plasma phase during the argon plasma treatment of PAAc films was investigated with optical emission spectroscopy. It was shown that during this plasma treatment carbon dioxide, water, and possibly hydrogen were liberated from the PAAc surface. By covering the surface of PAAc films with different materials (lithium fluoride, UV fused silica, and glass) during the plasma treatment, it was possible to differentiate between photochemically induced and particle-induced changes of the surface. This method was used to show that decarboxylation during the argon plasma treatment was caused by vacuum UV radiation (wavelength < 150 nm) and the decarboxylation/fluorination during the CF4 plasma treatment was induced by reactive fluorine-containing species from the plasma phase. Furthermore, during both processes, etching of the PAAc surface occurred. Based on these mechanisms, kinetic models were derived that could be used to describe the measured kinetic data adequately. © 1994 John Wiley & Sons, Inc. 相似文献
124.
Zhong Zhiyuan Schneiderbauer Stefan Dijkstra Pieter J. Westerhausen Matthias Feijen Jan 《Polymer Bulletin》2003,50(3):175-182
Summary
Single-site calcium initiators containing chelating tmhd
(H-tmhd = 2,2,6,6-tetramethylheptane-33-dione) ligands
[(THF)Ca(tmhd)]2[-N(SiMe3)2](-tmhd)
(2) and
[(THF)Ca(tmhd)]2[-OCH(Me)Ph](-tmhd)
(3) have been synthesized and
applied for the ring-opening polymerization of L-lactide and
-caprolactone. Both 2 and
3 were highly reactive and
promoted a fast polymerization of L-lactide and -caprolactone
to high monomer conversions under mild conditions (THF as a
solvent, room temperature). More importantly, results showed
that the ring-opening polymerizations of lactides and lactones
initiated by either 3 or
2 in the presence of equivalent
2-propanol are living, to provide polymers and block copolymers
of controlled molecular weights and tailored end-groups. The
polymerizations were first-order in monomer up to high
conversions, in which the in
situ initiating system 2/2-propanol revealed no induction period
and much faster polymerization kinetics as compared to
3. 相似文献
125.
Fábio J. P. Sousa Jan C. Aurich Walter L. Weingaertner Orestes E. Alarcon 《Journal of the American Ceramic Society》2007,90(11):3468-3477
Several kinds of glossiness pattern can be seen on the surface of porcelain stoneware tiles right after the polishing process, as a function of the kinematics performed by the polishing heads. For the newest generation of industrial polishing trains, where a transverse oscillation is included, there is still a great need for literature about the resulting patterns. This paper intends to find the spatial distribution of time under polishing analytically using the kinematics equations involved in the polishing process. The measured values of glossiness collected from three polished tiles are also presented. The importance of adopting a good kinematics for the polishing process has been highlighted, and the equations developed herein are useful tools for further attempts at optimizing the polishing process. 相似文献
126.
Fiber Coating Concepts for Brittle-Matrix Composites 总被引:4,自引:0,他引:4
Janet B. Davis Jan P. A. Löfvander Anthony G. Evans Ewald Bischoff Mario L. Emiliani 《Journal of the American Ceramic Society》1993,76(5):1249-1257
The current interest in tough, high-temperature materials has motivated fiber coating development for brittle-matrix composites with brittle reinforcements. Such coatings are needed for controlled interface debonding and frictional sliding. The system investigated in this study was sapphire fiber-reinforced alumina. This system is thermochemically stable for severe use conditions, exhibits little thermal expansion mismatch, and utilizes the excellent strength and creep resistance of sapphire reinforcements. Porous oxide and refractory metal coatings which satisfy requirements for toughness improvement in these composites were identified by employing a variety of newly developed mechanical testing techniques for determining the interfacial fracture energies and sliding resistances. 相似文献
127.
128.
Frantiek Hrabk Jan Lokaj Martin Tkaczyk Elena Morozova Valentina Eliseeva Leonid Chuiko Gennadii Voloshin 《大分子材料与工程》1986,144(1):219-227
A technical dye of the anthraquinone type was analyzed by GPC, mass spectroscopy, and elemental analysis. Along with the polymerizable component, N-[4-amino-3-methoxyanthraquinonyl-(1)] methacrylamide (I), it contained a saturated admixture, N-[4-amino-3-methoxyanthraquinonyl-(1)]-2-chloro-2-methylpropionamide (II). The homopolymerization of I was carried out, and admixture II was isolated and characterized. The copolymerization of the dye with styrene and methyl methacrylate was verified, and the retardation effect of II on the polymerization of these monomers was evaluated. 相似文献
129.
Benedikt Ley Corinna Ogonowski Jan Hess Tim Reichling Lin Wan Volker Wulf 《Behaviour & Information Technology》2014,33(8):815-828
Technological infrastructure at home is changing continuously and is becoming increasingly interconnected. Media devices, including the TV set, provide access to the Internet and offer manifold opportunities to consume media on demand. Additionally, personal devices, such as smartphones, also enable flexible consumption and sharing of media. Questions about how these technologies change the user's media usage and how these changes affect the social structure of a household, however, remain largely unanswered. In order to gain insight into the adoption of new technologies into daily routines, we explored these changes in respect of people's media usage in a qualitative long-term Living Lab study. We will present findings regarding personal routines, flexible integration of new devices into existing practices, influences on households as social systems and related issues in device access and collective use. We will highlight potentials and conflicts regarding device shifts and roles; restrictions in device access; social influences in the living room; and individual changes in media consumption. 相似文献
130.
Carsten Dachsbacher Jaroslav Křivánek Miloš Hašan Adam Arbree Bruce Walter Jan Novák 《Computer Graphics Forum》2014,33(1):88-104
Recent years have seen increasing attention and significant progress in many‐light rendering, a class of methods for efficient computation of global illumination. The many‐light formulation offers a unified mathematical framework for the problem reducing the full lighting transport simulation to the calculation of the direct illumination from many virtual light sources. These methods are unrivaled in their scalability: they are able to produce plausible images in a fraction of a second but also converge to the full solution over time. In this state‐of‐the‐art report, we give an easy‐to‐follow, introductory tutorial of the many‐light theory; provide a comprehensive, unified survey of the topic with a comparison of the main algorithms; discuss limitations regarding materials and light transport phenomena and present a vision to motivate and guide future research. We will cover both the fundamental concepts as well as improvements, extensions and applications of many‐light rendering. 相似文献