全文获取类型
收费全文 | 1414篇 |
免费 | 62篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 88篇 |
综合类 | 4篇 |
化学工业 | 468篇 |
金属工艺 | 38篇 |
机械仪表 | 31篇 |
建筑科学 | 35篇 |
矿业工程 | 4篇 |
能源动力 | 92篇 |
轻工业 | 165篇 |
水利工程 | 1篇 |
武器工业 | 1篇 |
无线电 | 64篇 |
一般工业技术 | 281篇 |
冶金工业 | 47篇 |
原子能技术 | 47篇 |
自动化技术 | 118篇 |
出版年
2023年 | 6篇 |
2022年 | 22篇 |
2021年 | 37篇 |
2020年 | 11篇 |
2019年 | 26篇 |
2018年 | 30篇 |
2017年 | 23篇 |
2016年 | 36篇 |
2015年 | 25篇 |
2014年 | 34篇 |
2013年 | 82篇 |
2012年 | 62篇 |
2011年 | 95篇 |
2010年 | 67篇 |
2009年 | 81篇 |
2008年 | 84篇 |
2007年 | 79篇 |
2006年 | 73篇 |
2005年 | 73篇 |
2004年 | 59篇 |
2003年 | 61篇 |
2002年 | 57篇 |
2001年 | 36篇 |
2000年 | 36篇 |
1999年 | 26篇 |
1998年 | 25篇 |
1997年 | 20篇 |
1996年 | 20篇 |
1995年 | 21篇 |
1994年 | 29篇 |
1993年 | 23篇 |
1992年 | 21篇 |
1991年 | 15篇 |
1990年 | 8篇 |
1989年 | 13篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 12篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有1484条查询结果,搜索用时 15 毫秒
31.
Koichi Hasegawa Hideki Nishimori Masahiro Tatsumisago Tsutomu Minami 《Journal of Materials Science》1998,33(4):1095-1098
Thick silica films were prepared by the electrophoretic sol–gel deposition technique in the presence of poly(acrylic acid) (PAA) using monodispersed silica particles; the particles were prepared by the sol–gel method, pre-heat treated and then re-dispersed in the mixture of H2O and ethanol. The weight of deposited silica films was maximized when 0.2 mass % of PAA against the whole amount of sol was added. The particles constructing the thick silica films were packed densely when the amount of added PAA was less than 0.2 mass%. The weight of the film increased with decrease in the content of H2O in the sol when a fixed amount of PAA was added. After the heat treatment of deposited films at 800 °C, crack-free silica films of about 30 m thickness were prepared. © 1998 Chapman & Hall 相似文献
32.
A. Takenaka Y. Ozeki S. Hiraki M. Hattori I. Motooka H. Nariai 《Journal of Materials Science》1996,31(24):6511-6513
The intercalation reaction of n-alkylamines from methyl- to hexadecylamine into -tin(IV) bis(hydrogenphosphate) has been investigated. The reaction was conducted by mixing the phosphate and solutions of the amines dissolved in water or benzene. The amine/ phosphate molar ratios in the reaction mixtures were 0.43, 0.85, 1.71 and 3.41. The nitrogen/phosphorus atomic ratio in the intercalation compound was not changed by the amine/phosphate molar ratio. The interlayer distances of the intercalates obtained in the reaction mixtures with molar ratios of 3.41 and 1.71 increased with an increase in the number of carbon atoms in the alkyl chain of the amine. The slope of the straight line obtained in plot of interlayer distance versus number of carbon atoms in the alkyl chain of the amine indicates that the amine molecules form a double layer in the interlayer space of the phosphate and are inclined at an approximate angle of 67.7° to the phosphate layer. The interlayer distances of the intercalates of butyl- to nonylamines obtained at the molar ratio of 0.85 are smaller than those of the corresponding compounds from the molar ratios of 3.41 and 1.71, while those of decyl- to hexadecylamine intercalates lie on the previously discussed line. This behaviour is interpreted by assuming kink formation in the short alkyl chains between the phosphate layers. 相似文献
33.
An implicit tenet of modern search heuristics is that there is a mutually exclusive balance between two desirable goals: search
diversity (or distribution), i.e., search through a maximum number of distinct areas, and, search intensity, i.e., a maximum
search exploitation within each specific area. We claim that the hypothesis that these goals are mutually exclusive is false
in parallel systems. We argue that it is possible to devise methods that exhibit high search intensity and high search diversity
during the whole algorithmic execution. It is considered how distance metrics, i.e., functions for measuring diversity (given
by the minimum number of local search steps between two solutions) and coordination policies, i.e., mechanisms for directing
and redirecting search processes based on the information acquired by the distance metrics, can be used together to integrate
a framework for the development of advanced collective search methods that present such desiderata of search intensity and
search diversity under simultaneous coexistence. The presented model also avoids the undesirable occurrence of a problem we
refer to as the ‘ergometric bike phenomenon’. Finally, this work is one of the very few analysis accomplished on a level of
meta-meta-heuristics, because all arguments are independent of specific problems handled (such as scheduling, planning, etc.),
of specific solution methods (such as genetic algorithms, simulated annealing, tabu search, etc.) and of specific neighborhood
or genetic operators (2-opt, crossover, etc.). 相似文献
34.
35.
This paper considers a multiobjective linear programming problem involving fuzzy random variable coefficients. A new fuzzy random programming model is proposed by extending the ideas of level set-based optimality and a stochastic programming model. The original problem involving fuzzy random variables is transformed into a deterministic equivalent problem through the proposed model. An interactive algorithm is provided to obtain a satisficing solution for a decision maker from among a set of newly defined Pareto optimal solutions. It is shown that an optimal solution of the problem to be solved iteratively in the interactive algorithm is analytically obtained by a combination of the bisection method and the simplex method. 相似文献
36.
Tetsu Ando Hirokazu Ohsawa Tadahiro Ueno Hideki Kishi Yutaka Okamura Satoshi Hashimoto 《Journal of chemical ecology》1993,19(4):787-798
Although several sex pheromones of the family Geometridae have been characterized, investigations on Japanese species are limited. In order to obtain more information, screening using known sex pheromones and their analogs was carried out. The (Z,Z,Z)-3,6,9-triunsaturated and (Z,Z)-6,9-diunsaturated hydrocarbons with straight C19-C21 chains were synthesized by the Grignard coupling reaction as a key step starting from linolenic and linoleic acids, respectively. Oxidation of the homoconjugated trienes withm-chloroperoxybenzoic acid yielded a 111 mixture of three monoepoxy derivatives that could be separated by silica gel chromatography. The chemical structure of each positional isomer was confirmed using two-dimensional NMR techniques and MS measurements, which enabled characteristic fragment ions from the isomers to be identified. Field tests using lures incorporating only one of the above six hydrocarbons or nine epoxides were carried out in a forest in Tokyo. Consequently, attraction of male moths of 14 geometrid species in addition to four species in another family, the Noctuidae, was observed. It was concluded that hydrocarbons with a homoconjugated polyene system and the monoepoxy derivatives are important components of sex pheromones produced by Japanese lepidopterous insects, particularly the geometrid moths. 相似文献
37.
Koji Ishida Ken Hirota Osamu Yamaguchi Hideki Kume Suguru Inamura Hiroki Miyamoto 《Journal of the American Ceramic Society》1994,77(5):1391-1395
In the system ZrO2 –Al2 O3 , a new method for preparing ZrO2 solid solutions from ZrCl4 and AlCl3 using hydrazine monohydrate is investigated. c -ZrO2 solid solutions containing up to ∼40 mol% Al2 O3 crystallize at low temperatures from amorphous materials. The formation mechanism is discussed from IR spectral data. The values of the lattice parameter α increase linearly from 0.5072 to 0.5105 nm with increasing Al2 O3 content. At higher temperatures, transformation of the solid solutions proceeds as follows: c ( SS ) → t ( ss ) → t ( ss ) +α-Al2 O3 → m +α-Al2 O3 . m -ZrO2 –α-Al2 O3 composite ceramics are fabricated by hot isostatic pressing for 2 h at 1250°C and 196 MPa. Microstructures and mechanical properties are examined, in connection with increasing Al2 O3 content. 相似文献
38.
WAN Tao AOKI Hideki KATOH Ayako 《武汉理工大学学报(材料科学英文版)》2005,20(B12):260-262
Radiofrequeut magnetron sputtering technique was used to produce calcium phosphate coated on the titurdum substrates, and the sputtered coating films were crystallized in an autoclave at 110℃ using a low temperature hydrothermal technique. The crystallization of as-sputtered coating film on the titanium substrates were amorphous calcium phosphate film. However, after the hydrothermal technique, calcium phosphate crystals grew and these were cohumnar crystal. The Ca/P ratio of sputtered coating films in 1.6 to 2.0. 相似文献
39.
Quinjiao Wang Kenji Itaka Hideki Minami Hitoshi Kawaji Hideomi Koinuma 《Science and Technology of Advanced Materials》2004,5(5-6):543
La1−xCaxVO3 composition-spread film library was fabricated by combinatorial pulsed laser deposition and their thermoelectric properties were evaluated paralelly by the multi-channel probes of Seebeck coefficient and electric conductivity. Concurrent X-ray analysis verified the formation of solid soluted films in the full composition range (0x1) as judged from the linear variation of the lattice constants. The Seebeck coefficients of La1−xCaxVO3 changed from a large negative value to almost zero with the increase of x, due presumably to the variation of valence in vanadium ions.The power factor in this library was as high as 0.6 μW/cm K2, which was obtained at x=0, i.e. pure LaVO3 grown at 800 °C. 相似文献
40.
One of the objectives of the high-temperature engineering test reactor (HTTR) is to demonstrate the effectiveness of high-temperature nuclear heat utilization, which aims to extend the application of nuclear heat to non-electric fields, especially to hydrogen production. As part of the development of the hydrogen production processes, laboratory-scale experiments of a high-temperature electrolysis of steam (HTES) had been carried out with a practical electrolysis tube with 12 solid-oxide cells connected in series. Using this electrolysis tube, hydrogen was produced at the maximum density of 44 N cm3/cm2 h at a electrolysis temperature of 950 °C. Thereafter, to improve hydrogen production performance, a self-supporting planar electrolysis cell with a practical size (80 mm × 80 mm of electrolysis area) was fabricated. In the preliminary electrolysis experiment carried out at 850 °C, the planar cell produced hydrogen at the maximum density of 38 N cm3/cm2 h, and the energy efficiency was almost as high as that obtained with the electrolysis tube at 950 °C. However, both electrolysis tubes and planar cells did not keep their integrity in one thermal cycle. Durability of the solid-oxide cell against the thermal cycle is one of the key issues of HTES. 相似文献