全文获取类型
收费全文 | 22212篇 |
免费 | 1341篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 404篇 |
综合类 | 71篇 |
化学工业 | 5048篇 |
金属工艺 | 653篇 |
机械仪表 | 531篇 |
建筑科学 | 1190篇 |
矿业工程 | 145篇 |
能源动力 | 407篇 |
轻工业 | 2981篇 |
水利工程 | 160篇 |
石油天然气 | 27篇 |
无线电 | 1430篇 |
一般工业技术 | 5735篇 |
冶金工业 | 909篇 |
原子能技术 | 197篇 |
自动化技术 | 3682篇 |
出版年
2023年 | 291篇 |
2022年 | 287篇 |
2021年 | 546篇 |
2020年 | 465篇 |
2019年 | 421篇 |
2018年 | 765篇 |
2017年 | 781篇 |
2016年 | 875篇 |
2015年 | 756篇 |
2014年 | 917篇 |
2013年 | 1742篇 |
2012年 | 1143篇 |
2011年 | 1384篇 |
2010年 | 1188篇 |
2009年 | 1044篇 |
2008年 | 1137篇 |
2007年 | 1139篇 |
2006年 | 825篇 |
2005年 | 653篇 |
2004年 | 526篇 |
2003年 | 512篇 |
2002年 | 518篇 |
2001年 | 427篇 |
2000年 | 364篇 |
1999年 | 299篇 |
1998年 | 313篇 |
1997年 | 290篇 |
1996年 | 260篇 |
1995年 | 222篇 |
1994年 | 173篇 |
1993年 | 159篇 |
1992年 | 138篇 |
1991年 | 117篇 |
1990年 | 99篇 |
1989年 | 87篇 |
1988年 | 92篇 |
1987年 | 82篇 |
1985年 | 164篇 |
1984年 | 171篇 |
1983年 | 111篇 |
1982年 | 113篇 |
1981年 | 138篇 |
1980年 | 105篇 |
1979年 | 92篇 |
1978年 | 95篇 |
1977年 | 83篇 |
1976年 | 91篇 |
1975年 | 93篇 |
1974年 | 72篇 |
1973年 | 72篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
The meat quality of M. longissimus muscle was evaluated in 851 pigs by using the Fibre Optic Probe (FOP) at three sites in the muscle and in both halves of the carcass. A systematic difference between sites was found, with the lowest light scattering (indicating the best meat quality) in the mid-part of the muscle and higher light scattering in the anterior and posterior parts. A non-systematic variation was also observed, with the opposite pattern in some animals, even though it was not frequent. A negative influence of the shackling was found, yielding higher FOP values in the shackled half.
Drip loss measurements in the Longissimus muscle, taken from another 100 pig carcasses, were evaluated using three methods. Drip loss, too, showed a considerable variation along the Longissimus muscle, with minimum losses around the last rib. Repeatability estimates, calculated from two non-consecutive pieces of the Longissimus dorsi muscle from each carcass, varied from 0·4 when keeping samples vacuum packed for 2 days, to 0·5 when the samples were either kept in plain plastic bags for 2 days or in a meat container with a squared inset for 1 or 2 days. 相似文献
33.
König Till Hagen S. P. Virtanen S. Galetz M. C. 《Metallurgical and Materials Transactions A》2022,53(11):4023-4033
Metallurgical and Materials Transactions A - Co-based superalloys have been developed as candidate materials to replace Ni-based superalloys in hot sections of turbine engines, however, their... 相似文献
34.
N. Schönfeldt 《Journal of the American Oil Chemists' Society》1968,45(2):80-82
The course of the lime soap-dispersing action of various surfactants has been examined by use of a titrimetric method. Two
types of dispersants can be distinguished. With the addition of a surfactant of the first type, the concentration of the dispersed
fatty acid increases gradually. If a surfactant of the second type is used, a definite increase of the fatty acid concentration
first occurs after the addition of considerable amounts of the dispersant.
Ethylene oxide adducts and sodium triethylene glycol monolauryl ether sulfate behave like dispersants of the first type whereas
sodium dodecylbenzenesulphonate and sodium lauryl sulfate belong to those of the second type. The dispersing action of both
types of surfactants is discussed. 相似文献
35.
H. R. Spiegel J. Juilfs U. Neubert K. J. Euler J. W. Beck D. Besdo H. Winter H. Becker W. Neuberger R. Jung K. Herfort H. Bühler H. Göppl H. W. Hahnemann W. Siegel 《Forschung im Ingenieurwesen》1970,36(2):64-68
Ohne Zusammenfassung
VDI 相似文献
36.
Pavel Krömer Jan Platoš Václav Snášel 《International journal of parallel programming》2014,42(5):681-709
Graphic processing units (GPUs) emerged recently as an exciting new hardware environment for a truly parallel implementation and execution of Nature and Bio-inspired Algorithms with excellent price-to-power ratio. In contrast to common multicore CPUs that contain up to tens of independent cores, the GPUs represent a massively parallel single-instruction multiple-data devices that can nowadays reach peak performance of hundreds and thousands of giga floating-point operations per second. Nature and Bio-inspired Algorithms implement parallel optimization strategies in which a single candidate solution, a group of candidate solutions (population), or multiple populations seek for optimal solution or set of solutions of given problem. Genetic algorithms (GA) constitute a family of traditional and very well-known nature-inspired populational meta-heuristic algorithms that have proved its usefulness on a plethora of tasks through the years. Differential evolution (DE) is another efficient populational meta-heuristic algorithm for real-parameter optimization. Particle swarm optimization (PSO) can be seen as nature-inspired multiagent method in which the interaction of simple independent agents yields intelligent collective behavior. Simulated annealing (SA) is global optimization algorithm which combines statistical mechanics and combinatorial optimization with inspiration in metallurgy. This survey provides a brief overview of the latest state-of-the-art research on the design, implementation, and applications of parallel GA, DE, PSO, and SA-based methods on the GPUs. 相似文献
37.
Polycrystalline Ag treated with O2 at pressures up to 1 bar and at temperatures up to 920 K was examined by TDS. It was found that the peak commonly observed at 595±25 K and assigned to adsorbed atomic oxygen (Oa) is shifted to higher desorption temperatures with rising dosing temperatures. Since saturation of the uptake was not possible either, this peak was identified as dissolved atomic oxygen (Od). The existence of a maximum for the O2 uptake after exposure at 820 K was found. Hence, under conditions of formaldehyde synthesis ( 920 K) the ability of the catalyst to dissolve oxygen is near its maximum. 相似文献
38.
A mathematical model to describe the protonation of weak acid ion-exchange resins with various acids has been developed. The charge profiles calculated using the theory are demonstrated by photographs. Interdiffusion coefficients in the resin phase have been determined and it is shown how they depend on the system parameters and on the properties of the resin. 相似文献
39.
Under the applied high reaction temperatures (900 K) the Ag surface is restructured and a tightly held oxygen species is formed on the surface (O) apart from O atoms dissolved in the bulk (O). Methanol oxidation to formaldehyde proceeds through this O species as demonstrated by application of a variety of spectroscopic techniques. 相似文献
40.
The rotational mobility of stable nitroxide radicals in PS, PMMA, PVC, PP and PE has been studied over a wide temperature range by the e.s.r. method. At temperatures T lower than Tg, spin probes act as kinetically independent particles, the rotational frequency of which is deter mined mainly by the micropore dimensions of the polymer and depends indirectly on the mobility of segments or side groups. 相似文献