全文获取类型
收费全文 | 2557篇 |
免费 | 81篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 32篇 |
综合类 | 6篇 |
化学工业 | 548篇 |
金属工艺 | 58篇 |
机械仪表 | 31篇 |
建筑科学 | 125篇 |
矿业工程 | 10篇 |
能源动力 | 100篇 |
轻工业 | 161篇 |
水利工程 | 6篇 |
石油天然气 | 15篇 |
无线电 | 252篇 |
一般工业技术 | 366篇 |
冶金工业 | 556篇 |
原子能技术 | 24篇 |
自动化技术 | 361篇 |
出版年
2022年 | 31篇 |
2021年 | 46篇 |
2020年 | 26篇 |
2019年 | 26篇 |
2018年 | 36篇 |
2017年 | 36篇 |
2016年 | 35篇 |
2015年 | 36篇 |
2014年 | 51篇 |
2013年 | 229篇 |
2012年 | 80篇 |
2011年 | 90篇 |
2010年 | 101篇 |
2009年 | 93篇 |
2008年 | 107篇 |
2007年 | 93篇 |
2006年 | 67篇 |
2005年 | 78篇 |
2004年 | 56篇 |
2003年 | 58篇 |
2002年 | 43篇 |
2001年 | 44篇 |
2000年 | 28篇 |
1999年 | 47篇 |
1998年 | 117篇 |
1997年 | 70篇 |
1996年 | 73篇 |
1995年 | 61篇 |
1994年 | 46篇 |
1993年 | 51篇 |
1992年 | 33篇 |
1991年 | 31篇 |
1990年 | 42篇 |
1989年 | 20篇 |
1988年 | 25篇 |
1987年 | 28篇 |
1986年 | 36篇 |
1985年 | 24篇 |
1984年 | 30篇 |
1983年 | 26篇 |
1982年 | 30篇 |
1981年 | 35篇 |
1980年 | 21篇 |
1979年 | 21篇 |
1978年 | 20篇 |
1977年 | 27篇 |
1976年 | 19篇 |
1975年 | 31篇 |
1974年 | 19篇 |
1973年 | 18篇 |
排序方式: 共有2651条查询结果,搜索用时 760 毫秒
51.
A Sulzer SMX mixer was used to disperse gas into viscous, Newtonian and non-Newtonian fluids. The investigation covered the effect of the dispersed phase volume fraction, the viscosity of the continuous phase, the mixer length and the power draw. The flow regime was kept laminar in all the experiments. The dispersion of gas was carried out with gas concentrations between 1% and 7% in volume. Using the “process viscosity” concept, it was possible to collapse all the measured sizes on a single master curve by using the energy consumption in the mixer as the common variable between the experiments. Comparison was made with a Kenics mixer. The SMX mixer was found to be better adapted to the dispersion task due to its internal structure. 相似文献
52.
Henry J. Pownall Joel D. Morrisett James T. Sparrow Louis C. Smith James Shepherd Richard L. Jackson Antonio M. Gotto Jr. 《Lipids》1979,14(4):428-434
The human plasma high density lipoproteins (HDL) are a heterogeneous ensemble of five proteins associated with both neutral
and polar lipids. The sequences of all five proteins are known. ApoA-I and apoA-II are the major protein components; apoC-I,
apoC-II and apoC-III are the minor protein components. All these apoproteins spontaneously recombine with phospholipids to
give stable lipid-protein complexes and freely exchange between the two major HDL subclasses, HDL2 and HDL3. In addition, ApoC-I, apoC-II, and apoC-III exchange between HDL and very low density lipoproteins. Furthermore, certain
HDL apoproteins are activators for plasma enzymes that are important in lipid metabolism. ApoA-I and apoC-I activate lecithin/cholesterol
acyltransferase; apoC-II is an activator of lipoprotein lipase. The regions of apoC-I and apoC-II that are involved in the
activation of these enzymes have been localized with synthetic peptides. Studies of synthetic and native fragments of apoA-II,
apoC-I, apoC-II, and apoC-III as well as model lipid-binding peptides have identified specific regions with structural features
common to lipid-binding proteins. These special properties, which include helical potential, sequences with a critical amphipathic
length, and high hydrophobicity of the nonpolar side of the amphipathic helix, are the determinants of HDL structure and metabolism. 相似文献
53.
为获得有抗氧化活性的工业用酵母菌株,对2株来源于原料乳中有较强抗氧化活性的酵母菌进行鉴定.根据菌株的表型、生理生化特征和基因型的特性,初步将这2株菌鉴定为毕赤氏发酵酵母(Pichia fermentans).将这2株酵母菌在高温灭菌(UHT)牛乳中培养以研究其对牛乳主要成分的影响,结果表明:这2株酵母能在UHT牛乳中产乙醇,具有促进蛋白水解活性与脂肪水解活性的能力,能有效提高乳中的游离氨基酸和脂肪酸的含量. 相似文献
54.
Most heterogeneous catalysts are either supported on some kind of porous material or the catalyst itself is porous. To satisfy practical constraints such as pressure drop, handling, and separation from products, these catalysts are generally pelletized. Very often the overall chemical reaction rates within these catalyst pellets are determined by a complicated interaction of internal and external transport effects with the intrinsic kinetic rate at the active surface. 相似文献
55.
Torsion and normal force measurements were made during single step stress relaxation experiments on a polymeric glass (PMMA). Isochronal data were analysed using an approach adapted from that developed by Penn and Kearsley1 (for incompressible elastic materials) to determine the derivatives , and of the time dependent strain potential function. and are determined from existing solution to the torsion of an incompressible cylinder. A special solution to the torsion of a compressible cylinder is presented and it is shown that the values of and obtained using this solution to analyse the data do not differ greatly from those obtained using the incompressible solution. It is found from both solutions that is negative and increases towards zero with increasing time and deformation while is positive, greater in magnitude than and decreases towards zero with increasing time and deformation. These results were unexpected and a full understanding of their meaning has yet to be reached. 相似文献
56.
Effect of Microstructure on the Tribological and Mechanical Properties of CuO-Doped 3Y-TZP Ceramics 总被引:1,自引:0,他引:1
Shen Ran Louis Winnubst Dave H. A. Blank Henry R. Pasaribu Jan-Willem Sloetjes Dik J. Schipper 《Journal of the American Ceramic Society》2007,90(9):2747-2752
Dense 8 mol% CuO-doped 3Y-TZP ceramics were prepared by pressureless sintering for 8 h at 1500° and 1550°C, respectively. Transmission electron spectroscopy revealed that the ceramic sintered at 1500°C exhibits grain boundaries free of any amorphous phase, while crystalline copper-oxide grains were found in the zirconia matrix, whereas the sample sintered at 1550°C contains a Cu-rich amorphous grain boundary layer. The tribological behavior of these materials was tested under dry-sliding conditions using a pin-on-disk tribometer. The material sintered at 1500°C showed self-lubrication resulting in a low coefficient of friction ( f ) of 0.2–0.3 and a low specific wear rate ( k ) ≪ 10−6 mm3 ·(N·m)−1 . In contrast, the material sintered at 1550°C showed poor tribological behavior ( f =0.8–0.9; k ≫ 10−6 mm3 ·(N·m)−1 under the same conditions. The difference in the tribological behavior of these two materials was interpreted on the basis of mechanical properties and microstructural characteristics. 相似文献
57.
Virginie Boy Wajdi Ben Khalifa Lucie Drvillon Yves Leme Thomas Lendormi Jean‐Louis Lanoisell 《加拿大化工杂志》2021,99(1):120-134
An original drying process combining air impingement and intermittent drying was studied on apple slices and mango cubes. The influence of four operating parameters (air velocity, drying/tempering periods, upper height, and air temperature) on the drying time and on the drying rate was evaluated. Continuous and intermittent drying were compared. The intermittency α = 1/7 (τon = 10 seconds and τoff = 60 seconds) gave the best results. A time savings of 54% for apple and 67% for mango was reached. In continuous drying, a time savings of 4620 seconds was observed by increasing the air velocity from 6 to 40 m s?1 for apple. Air temperatures of 328 K for apple and of 328 K or 338 K for mango were determined as optimum to prevent case‐hardening. Experimental results were fitted with the analytical solution of Fick's second law and the modified Page equation (average values R2 = 0.985 and 0.961, for apple and mango, respectively). For both products, the apparent moisture diffusivity Dapp, the drying constant k, the drying coefficient n, and the activation energy Ea, were identified. Activation energies calculated from the analytical solution were 30.3 and 36.8 kJ mol?1 and were 25.4 and 30.0 kJ mol?1 using the modified Page equation for apple and mango, respectively. Mango has an increased temperature sensitivity and thus will need less energy for drying than apple. 相似文献
58.
Renaud Merlet Louis Winnubst Arian Nijmeijer Mohammad Amirilargani Ernst J. R. Sudhölter Louis C. P. M. de Smet Sara Salvador Cob Pieter Vandezande Matthieu Dorbec Soraya Sluijter Henk van Veen Yvonne VanDelft Ingrid Wienk Petrus Cuperus Subhalaxmi Behera Yusak Hartanto Ivo F. J. Vankelecom Patrick de Wit 《化学,工程师,技术》2021,93(9):1389-1395
Organic solvent nanofiltration (OSN) is gradually expanding from academic research to industrial implementation. The need for membranes with low and sharp molecular weight cutoffs that are able to operate under aggressive OSN conditions is increasing. However, the lack of comparable and uniform performance data frustrates the screening and membrane selection for processes. Here, a collaboration is presented between several academic and industrial partners analyzing the separation performance of 10 different membranes using three model process mixtures. Membrane materials range from classic polymeric and thin film composites (TFCs) to hybrid ceramic types. The model solutions were chosen to mimic cases relevant to today's industrial use: relatively low molar mass solutes (330–550 Da) in n-heptane, toluene, and anisole. 相似文献
59.
Michael P. Balogh Camille Y. Jones J.F. Herbst Louis G. Hector Jr. Matthew Kundrat 《Journal of Alloys and Compounds》2006,420(1-2):326-336
Half-Heusler compounds of Sn-doped TiCoSb “TiCoSnxSb1−x (x = 0.0, 0.01, and 0.05)” were prepared and their thermoelectric properties were measured above room temperature. From the EDX analysis, all the samples have three phases: the TiCoSnxSb1−x, Co-rich, and Ti-rich phases. The values of the thermoelectric power increase with Sn doping, and a positive thermoelectric power is obtained in the sample of TiCoSn0.05Sb0.95. The thermal conductivity decreases both with increasing temperature and with Sn content. The maximum value of ZT for p-type material is 0.030 at 988 K in the sample of TiCoSn0.05Sb0.95. 相似文献
60.
Mount Emily Gaultney Daniel Vrijsen Geert Adams Michael Baek So-Young Hudek Kai Isabella Louis Crain Stephen van Rynbach Andre Maunz Peter Kim Jungsang 《Quantum Information Processing》2016,15(12):5281-5298
Quantum Information Processing - Many of the challenges of scaling quantum computer hardware lie at the interface between the qubits and the classical control signals used to manipulate them.... 相似文献