全文获取类型
收费全文 | 5218篇 |
免费 | 126篇 |
国内免费 | 27篇 |
专业分类
电工技术 | 412篇 |
综合类 | 17篇 |
化学工业 | 1509篇 |
金属工艺 | 136篇 |
机械仪表 | 139篇 |
建筑科学 | 189篇 |
矿业工程 | 1篇 |
能源动力 | 244篇 |
轻工业 | 506篇 |
水利工程 | 19篇 |
石油天然气 | 7篇 |
无线电 | 287篇 |
一般工业技术 | 919篇 |
冶金工业 | 190篇 |
原子能技术 | 214篇 |
自动化技术 | 582篇 |
出版年
2023年 | 31篇 |
2022年 | 60篇 |
2021年 | 98篇 |
2020年 | 52篇 |
2019年 | 63篇 |
2018年 | 77篇 |
2017年 | 64篇 |
2016年 | 112篇 |
2015年 | 81篇 |
2014年 | 153篇 |
2013年 | 320篇 |
2012年 | 185篇 |
2011年 | 308篇 |
2010年 | 258篇 |
2009年 | 279篇 |
2008年 | 314篇 |
2007年 | 262篇 |
2006年 | 203篇 |
2005年 | 220篇 |
2004年 | 176篇 |
2003年 | 161篇 |
2002年 | 165篇 |
2001年 | 105篇 |
2000年 | 96篇 |
1999年 | 97篇 |
1998年 | 107篇 |
1997年 | 76篇 |
1996年 | 73篇 |
1995年 | 55篇 |
1994年 | 83篇 |
1993年 | 69篇 |
1992年 | 55篇 |
1991年 | 75篇 |
1990年 | 52篇 |
1989年 | 77篇 |
1988年 | 65篇 |
1987年 | 39篇 |
1986年 | 73篇 |
1985年 | 56篇 |
1984年 | 53篇 |
1983年 | 57篇 |
1982年 | 60篇 |
1981年 | 47篇 |
1980年 | 42篇 |
1979年 | 41篇 |
1978年 | 41篇 |
1977年 | 29篇 |
1976年 | 28篇 |
1975年 | 18篇 |
1973年 | 17篇 |
排序方式: 共有5371条查询结果,搜索用时 15 毫秒
941.
942.
Takayama H Takahashi S Moriya T Osada H Iwabuchi Y Kanoh N 《Chembiochem : a European journal of chemical biology》2011,12(18):2748-2752
Seeing below the surface: A small-molecule droplet array platform on an NADH-immobilized solid surface and a biotinylated acetophenone derivative were developed to identify the substrate candidates for soluble P450 enzymes of interest. This methodology is thought to be easily applicable to other class I P450 systems, including those that use NADPH as cofactor. 相似文献
943.
Mamitsuka H 《Chimia》2011,65(1-2):10-13
Carbohydrates or glycans are major cellular macromolecules, working for a variety of vital biological functions. Due to long-term efforts by experimentalists, the current number of structurally different, determined carbohydrates has exceeded 10,000 or more. As a result data mining-based approaches for glycans (or trees in a computer science sense) have attracted attention and have been developed over the last five years, presenting new techniques even from computer science viewpoints. This review summarizes cutting-edge techniques for glycans in each of the three categories of data mining: classification, clustering and frequent pattern mining, and shows results obtained by applying these techniques to real sets of glycan structures. 相似文献
944.
Hiroki Yoshioka Masaki Ota Yoshiyuki Sato Masaru Watanabe Hiroshi Inomata Richard L. Smith Jr. Cor J. Peters 《American Institute of Chemical Engineers》2011,57(1):265-272
Decomposition kinetics and recycle of hydrogen–tetrahydrofuran (H2–THF) clathrate hydrates were investigated with a pressure decay method at temperatures from 265.1 to 273.2 K, at initial pressures from 3.1 to 8.0 MPa, and at stoichiometric THF hydrate concentrations for particle sizes between 250 and 1000 μm. The decomposition was modeled as a two‐step process consisting of H2 diffusion in the hydrate phase and desorption from the hydrate cage. The adsorption process occurred at roughly two to three times faster than the desorption process, whereas the diffusion process during formation was slightly higher (ca. 20%) than that during decomposition. Successive formation and decomposition cycles showed that occupancy seemed to decrease only slightly with cycling and that there were no large changes in hydrate structure due to cycling. Results provide evidence that the formation and decomposition of H2 clathrate hydrates occur reversibly and that H2 clathrate hydrates can be recycled with pressure. © 2010 American Institute of Chemical Engineers AIChE J, 2011 相似文献
945.
Jin Seog Gwag Jonghoon Yi Jin Hyuk Kwon Makoto Yoneya Hiroshi Yokoyama 《应用聚合物科学杂志》2011,119(1):325-329
We demonstrate the alignment characteristics of a nematic liquid crystal on the surface of a nanoimprinted material that is a functionally graduated composite suitable for the alignment of a liquid crystal on a groove surface processed by nanoimprinting lithography. With the electro‐optic characteristics shown in twisted nematic and in‐plane switching modes, the potential liquid crystal applications are examined. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
946.
One-dimensional carbon nanotube (CNT) junctions with interesting device characteristics have been designed by encapsulating p- and n-type organic molecules into CNTs with electrophilic tetracyano-p-quinodimethane (TCNQ) and nucleophilic tetrakis(dimethylamino)ethylene (TDAE) molecules in order to explore the effect of encapsulation of organic molecules and rectifying behaviors of the designed one-dimensional CNT p-n junctions. Our results show that p- and n-type doping of CNTs and their associated charge transfer play an important role in determining the electron transport characteristics and lead to materials with unique properties, p-n junction diode, i.e. Zener-like diode. Furthermore, we show that the operational device characteristics of non-covalently doped CNT junctions originate from the distinct response of intrinsic transmission peaks of pure CNTs according to the type of dopant and the applied bias. We believe that the results give an insight into the design and implementation of various electronic logic functions based on CNTs for applications in the field of nanoelectronics. 相似文献
947.
Lu S Ji L He W Dai P Yang H Arimochi M Yoshida H Uchida S Ikeda M 《Nanoscale research letters》2011,6(1):576
We report the initial results of GaAs and GaInP solar cells grown by all solid-state molecular-beam-epitaxy (MBE) technique. For GaAs single-junction solar cell, with the application of AlInP as the window layer and GaInP as the back surface field layer, the photovoltaic conversion efficiency of 26% at one sun concentration and air mass 1.5 global (AM1.5G) is realized. The efficiency of 16.4% is also reached for GaInP solar cell. Our results demonstrate that the MBE-grown phosphide-contained III-V compound semiconductor solar cell can be quite comparable to the metal-organic-chemical-vapor-deposition-grown high-efficiency solar cell. 相似文献
948.
Hitomi Hiruma Hiroshi ToidaTakao Hanawa Hitoshi SakuragiYoshiaki Suzuki 《Surface & coatings technology》2011,206(5):905-910
Expanded polytetrafluoroethylene (ePTFE), which is a durable biomaterial because of its excellent biological inertness, is now widely used for prostheses in clinical medicine. However, conversely, the inert nature of ePTFE results in poor adaptability to the surrounding tissue due to lack of a cell-adhesive property. In this study, the surface of ePTFE was modified with ion beam irradiation to improve the blood compatibility. The surface modification of ePTFE sheets by He+, Ne+, Ar+ and Kr+ ion beams was performed at an energy of 150 keV with fluences of 1 × 1014, 5 × 1014 and 1 × 1015 ions/cm2. To investigate anti-thrombogenicity, Ca2+-replenished platelet-rich plasma (PRP) was placed in contact with the surfaces for 10 min. Compared to the non-modified ePTFE surface, platelet response was inhibited on the surfaces modified with He+, Ne+ and Ar+: 5 × 1014 and 1 × 1015 ions/cm2, and Kr+: 5 × 1014 ions/cm2; however, platelet response was promoted on the surfaces modified with He+, Ne+ and Ar+: 1 × 1014 ions/cm2, and Kr+: 1 × 1014 and 1 × 1015 ions/cm2. The significant morphological changes in ePTFE surface associated with ion beam modification are thought to be one of the reasons for the inhibition of platelet response. Endothelial cells were cultured on the surfaces for 3 days to evaluate the cellular response. Endothelial cell growth was significantly promoted on all of the surfaces of ion beam-modified ePTFE, although the non-modified ePTFE surface dramatically inhibited this growth. It is concluded that ion beam modification of ePTFE surface can improve the blood compatibility through not only the promotion of endothelial cell growth but also the inhibition of platelet response. 相似文献
949.
Kenta Adachi Kensuke Honda Suzuko Yamazaki Tomoyuki Hirano Hiroshi Kurokawa Akinobu Wakabayashi Paul H. Kasai Katsuhiko Nakamae Hitoshi Iwabuki Koji Murakami 《Polymer Engineering and Science》2011,51(4):632-640
The vinyltrimethoxysilane‐grafted ethylene‐propylene copolymer/trifunctional methoxysilane (EPR‐g‐VTMS/RTMS) composites were prepared via in situ silica sol–gel reactions. Five trifunctional methoxysilane compounds (n‐hexyltrimethoxysilane, n‐decyltrimethoxysilane, n‐tetradecyltrimethoxysilane, n‐octadecyltrimethoxysilane, and phenyltrimethoxysilane) have been selected for this study. The water‐cross‐linked EPR‐g‐VTMS/RTMS composites were characterized by attenuated total reflectance‐Fourier transform infrared spectroscopy, gel content, solid‐state 29Si CP/MAS NMR, wide‐angle x‐ray scattering, tensile strength, and field emission scanning electron microscopy measurements. The type of RTMS additive has a substantial influence on the nature of siloxane band networks and eventually the mechanical tensile properties. This finding suggests that the interaction and/or entanglement between the EPR‐g‐VTMS matrix and the substituent of the RTMS additives are crucial for the modifying mechanical properties. Moreover, for the water‐cross‐linked EPR‐g‐VTMS/CnTMS (n = 6, 10, 14, and 18) composites, the joint evidence provided by attenuated total reflectance‐Fourier transform infrared spectroscopy, 29Si CP/MAS NMR, and wide‐angle x‐ray scattering results suggested the formation of ladder‐type poly(n‐alkyl silsesquioxane)s and the presence of the highly ordered structure with a thickness equal to the length of two n‐alkyl groups in all‐trans conformation. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers. 相似文献
950.
The structure and properties of polycarbonate (PC)/poly(methyl methacrylate) (PMMA) blends fabricated using a high‐shear extruder at different shear rates were investigated. It was found that the morphologies of the blends were greatly dependent on the shear rate exerted during melt processing. High‐shear processing leads to a nanostructured PC/PMMA blend, in which PMMA domains with a size of less than 50 nm are homogeneously dispersed in the PC matrix. The prepared nanostructured blends exhibit not only excellent optical properties with a transmittance of more than 90% in the visible region but also a higher modulus than pure PC. In contrast, the PMMA domain size ranges from submicron to micrometer for the same blends processed at a low‐shear rate. These blends are opaque and display much lower elongation at break compared with the blends processed at a high‐shear rate. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers 相似文献