全文获取类型
收费全文 | 2193篇 |
免费 | 212篇 |
专业分类
电工技术 | 21篇 |
综合类 | 29篇 |
化学工业 | 811篇 |
金属工艺 | 25篇 |
机械仪表 | 42篇 |
建筑科学 | 98篇 |
矿业工程 | 6篇 |
能源动力 | 54篇 |
轻工业 | 384篇 |
水利工程 | 41篇 |
石油天然气 | 4篇 |
无线电 | 82篇 |
一般工业技术 | 374篇 |
冶金工业 | 126篇 |
原子能技术 | 7篇 |
自动化技术 | 301篇 |
出版年
2024年 | 12篇 |
2023年 | 22篇 |
2022年 | 24篇 |
2021年 | 177篇 |
2020年 | 96篇 |
2019年 | 85篇 |
2018年 | 91篇 |
2017年 | 96篇 |
2016年 | 112篇 |
2015年 | 94篇 |
2014年 | 126篇 |
2013年 | 177篇 |
2012年 | 140篇 |
2011年 | 203篇 |
2010年 | 119篇 |
2009年 | 119篇 |
2008年 | 127篇 |
2007年 | 98篇 |
2006年 | 70篇 |
2005年 | 50篇 |
2004年 | 46篇 |
2003年 | 49篇 |
2002年 | 43篇 |
2001年 | 25篇 |
2000年 | 29篇 |
1999年 | 28篇 |
1998年 | 29篇 |
1997年 | 12篇 |
1996年 | 8篇 |
1995年 | 15篇 |
1994年 | 14篇 |
1993年 | 13篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有2405条查询结果,搜索用时 15 毫秒
101.
Walter F Schroeder Silvana L Asmussen Wayne D Cook Claudia I Vallo 《Polymer International》2011,60(9):1362-1369
The efficiency of 4,4′‐bis(N,N‐diethylamino)benzophenone (DEABP) for the polymerization of dimethacrylate monomers in thick sections ( 1 – 2 mm) was studied. DEABP (λmax = 365 nm) represents a complete initiating system as it contains both ketone and amine functional groups. During irradiation, DEABP photobleaches at a fast rate causing deeper penetration of light through the underlying layers, but the photoinitiation efficiency (rate of polymerization per photon absorption rate) is relatively poor. As a result, irradiation of methacrylate monomers at 365 nm results in a slow average polymerization rate and a reduced monomer conversion for thick sections due to the light attenuation caused by the high absorptivity of DEABP and photolysis products. These results highlight the inherent interlinking of light attenuation and photobleaching rate in polymerization of thick sections. Copyright © 2011 Society of Chemical Industry 相似文献
102.
Microstructure models for cellular materials 总被引:2,自引:0,他引:2
Laguerre tessellations generated by random sphere packings are promising models for the microstructure of cellular or polycrystalline materials. In this paper, the case of hard sphere packings with lognormal or gamma distributed volumes is investigated. The dependence of the geometric characteristics of the Laguerre cells on the volume fraction of the sphere packing and the coefficient of variation of the volume distribution is studied in detail. The moments of certain cell characteristics are described by polynomials, which allows to fit tessellation models to real materials without further simulations. The procedure is demonstrated by the examples of open polymer and aluminium foams. 相似文献
103.
Kirsten Bobzin Nazlim Bagcivan Arnold Gillner Claudia Hartmann Jens Holtkamp Walter Michaeli Fritz Klaiber Maximilian Sch?ngart Sebastian Thei? 《Production Engineering》2011,5(4):415-422
Molding of micro structures by injection molding leads to special requirements for the molds e.g. regarding wear resistance
and low release forces of the molded components. At the same time it is not allowed to affect the replication precision. Physical
vapor deposition (PVD) is one of the promising technologies for applying coatings with adapted properties like high hardness,
low roughness, low Young’s modulus and less adhesion to the melt of polymers. Physical vapor deposition technology allows
the deposition of thin films on micro structures. Therefore, the influence of these PVD layers on the contour accuracy of
the replicated micro structures has to be investigated. For this purpose injection mold inserts were laser structured with
micro structures of different sizes and afterwards coated with two different coatings, which were deposited by a magnetron
sputter ion plating PVD technology. After deposition, the coatings were analyzed by techniques regarding hardness, Young’s
modulus and morphology. The geometries of the micro structures were analyzed by scanning electron microscopy before and after
coating. Afterwards, the coated mold inserts were used for injection molding experiments. During the injection molding process,
a conventional and a variothermal temperature control of the molds were used. The molded parts were analyzed regarding roughness,
structure height and structure width by means of laser microscopy. 相似文献
104.
105.
Erasmo Viola Claudia Belmonte Giuseppe Viola 《International Journal of Fracture》2009,157(1-2):175-192
In this paper the elastostatic solution of an inclined crack problem has been analyzed. The approach is analogous to the one proposed over the past years for orthotropic materials by Piva andViola (1988) (Eng Fract Mech, 29: 535–548), and it may be considered an alternative to the mathematical formalisms currently used. A general expression of the stress field is determined in terms of complex potentials. The stress distribution and the displacement field in the proximity of the crack tip are finally obtained. An expression of the energy release rate is provided in terms of the field intensity factors. Numerical results are presented and discussed under different remote electro-mechanical loading conditions and varying the crack inclination. Particular attention has been focused on the effect of the lateral load on the fracture quantities and on the direction of the incipient branching angle. 相似文献
106.
Claudia Valéria Távora Cabral Antônia Sônia Alves C. Diniz Olga Moraes Toledo 《Solar Energy》2010,84(9):1628-1636
Photovoltaic systems utilize solar energy to generate electrical energy to meet load demands. Optimal sizing of these systems includes the characterization of solar radiation. Solar radiation at the Earth’s surface has random characteristics and has been the focus of various academic studies. The objective of this study was to stochastically analyze parameters involved in the sizing of photovoltaic generators and develop a methodology for sizing of stand-alone photovoltaic systems. Energy storage for isolated systems and solar radiation were analyzed stochastically due to their random behavior. For the development of the methodology proposed stochastic analysis were studied including the Markov chain and beta probability density function. The obtained results were compared with those for sizing of stand-alone using from the Sandia method (deterministic), in which the stochastic model presented more reliable values. Both models present advantages and disadvantages, however, the stochastic one is more complex and provides more reliable and realistic results. 相似文献
107.
Claudia Loitsch Gerhard Weber Nikolaos Kaklanis Konstantinos Votis Dimitrios Tzovaras 《User Modeling and User-Adapted Interaction》2017,27(3-5):445-491
Moving between devices is omnipresent, but not for people with disabilities or those who require specific accessibility options. Setting up assistive technologies or finding settings to overcome a certain barrier can be a demanding task for people without technical skills. Context-sensitive adaptive user interfaces are advancing, although migrating access features from one device to another is very rarely addressed. In this paper, we describe the knowledge-based component of the Global Public Inclusive Infrastructure that infers how a device shall be best configured at the operating system layer, the application layer and the web layer to meet the requirements of a user including possible special needs or disabilities. In this regard, a mechanism to detect and resolve conflicting accessibility policies as well as recommending preference substitutes is a main requirement, as elaborated in this paper. As the proposed system emulates decision-making of accessibility experts, we validated the automatic deduced configurations against manual configurations of ten accessibility experts. The assessment result shows that the average matching score of the developed system is high. Thus, the proposed system can be considered capable of making precise decisions towards personalizing user interfaces based on user needs and preferences. 相似文献
108.
Thermal and reduction-oxidation stability of substituted LaMn1−yCoyO3 perovskite-type oxides (0.0 ≤ yCo ≤ 1.0) prepared by the citrate route have been studied by means of surface area, X-ray diffraction, FTIR spectroscopy and magnetic properties. The perovskite orthorhombic structure is found for yCo ≤ 0.5, with the exception of yCo = 0.1, which corresponds better to rhombohedral LaMnO3.15. For yCo > 0.5 the diffraction profiles are quite similar to the cobaltite’s rhombohedral structure. Magnetic iso-field studies (ZFC-FC) reveal that, for yCo ≤ 0.50, the system presents an antiferromagnetic canted-like ordering of the Mn/Co sublattice, in which the presence of divalent Co ion creates Mn3+-Mn4+ pairs that interact ferromagnetically through the oxygen orbital. This interpretation is confirmed by the magnetization loops, in which the magnetic moment increases when substituting Mn for Co. Therefore, the general trend is: for yCo ≤ 0.5, the Co ions are inserted in the manganite structure and for yCo > 0.5, the Mn ions are inserted in cobaltite structure. The enhancement of the ferromagnetic properties and the thermal stability against reduction for yCo = 0.5 is attributed to optimized Co2+-Mn4+ interactions. 相似文献
109.
Sara Morandi Claudia Focardi Mila Nocentini Marta Puggelli Gabriella Caminati 《Food Analytical Methods》2009,2(4):271-281
The development of a fast and reliable screening method for the determination of tetracycline residues in milk is described
and compared to high-performance liquid chromatography. The method is based on europium-sensitized luminescence: The emissive
properties of the lanthanide cation are used as a fingerprint of europium (III) complexation with tetracycline. The optimization
of the extraction and purification procedures provided a simple and convenient route to prepare stable tetracycline samples
that can safely resist freezing cycles. The method is validated for the first time in milk matrix: The results show that accuracy
and precision of the method meet complaints with the criteria of the Commission Decision 2002/657/EC. The proposed method
has a false compliant rate (β error) lower than 5%. 相似文献
110.