全文获取类型
收费全文 | 2864篇 |
免费 | 50篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 25篇 |
综合类 | 1篇 |
化学工业 | 476篇 |
金属工艺 | 41篇 |
机械仪表 | 51篇 |
建筑科学 | 63篇 |
矿业工程 | 9篇 |
能源动力 | 76篇 |
轻工业 | 135篇 |
水利工程 | 13篇 |
石油天然气 | 19篇 |
无线电 | 213篇 |
一般工业技术 | 382篇 |
冶金工业 | 1046篇 |
原子能技术 | 27篇 |
自动化技术 | 338篇 |
出版年
2022年 | 18篇 |
2021年 | 45篇 |
2020年 | 31篇 |
2019年 | 33篇 |
2018年 | 33篇 |
2017年 | 32篇 |
2016年 | 21篇 |
2015年 | 28篇 |
2014年 | 48篇 |
2013年 | 79篇 |
2012年 | 68篇 |
2011年 | 67篇 |
2010年 | 66篇 |
2009年 | 64篇 |
2008年 | 80篇 |
2007年 | 79篇 |
2006年 | 73篇 |
2005年 | 61篇 |
2004年 | 57篇 |
2003年 | 67篇 |
2002年 | 48篇 |
2001年 | 61篇 |
2000年 | 53篇 |
1999年 | 63篇 |
1998年 | 258篇 |
1997年 | 158篇 |
1996年 | 147篇 |
1995年 | 102篇 |
1994年 | 96篇 |
1993年 | 70篇 |
1992年 | 36篇 |
1991年 | 46篇 |
1990年 | 42篇 |
1989年 | 42篇 |
1988年 | 47篇 |
1987年 | 37篇 |
1986年 | 27篇 |
1985年 | 51篇 |
1984年 | 35篇 |
1983年 | 24篇 |
1982年 | 34篇 |
1981年 | 30篇 |
1980年 | 20篇 |
1979年 | 24篇 |
1978年 | 24篇 |
1977年 | 42篇 |
1976年 | 52篇 |
1974年 | 22篇 |
1973年 | 18篇 |
1972年 | 17篇 |
排序方式: 共有2915条查询结果,搜索用时 31 毫秒
141.
Micha Klein 《国际水》2013,38(4):244-248
Sharing water in the Jordan basin has been a key topic in the recent peace talks between Israel and its neighbors. Knowing the quantity of water available is a prerequisite to water sharing. Many different values have been published in recent years. Different sources report Jordan's discharge flow into Lake Kinneret anywhere from 460 to 800 Mm3/year. The aim of this article is to present a water balance for the Jordan basin for a 15-year period. The years 1977–1978 to 1991–1992 were studied for the basin's water budget, as they represent the present day (1998) land use. The results show that Lake Kinneret has a yearly average input (= output) of 770 Mm3. Israel uses some 800 Mcm3/year from the entire Jordan basin, of which 440 Mm3 is used within the basin and the rest outside. There is about 100 Mm3 for future utilization in the watershed. The yearly Jordan's discharge to the Dead Sea is 220–250 Mm3. Reporting by various secondary data sources is compared to primary data findings to illustrate the great variability of data reporting and to provide annual flow estimates, based largely on primary sources, for the Upper Jordan River. 相似文献
142.
Klein Lisa 《机械工程学报(英文版)》2002,15(2):182-185
The sol-gel process, using aqueous solutions, is used for dip coating onto substrates of 316L stainless steel. A suitable coating of LiCoO2 is achieved by varying the thickness and heat treating at 650℃ for 3 h. Thermal analysis, X-ray diffraction analysis and SEM are carried out to characterize the microstructure of the coatings. The results show that the coating transforms from an amorphous gel to crystalline phases above 350℃, and show a porous structure. The phase transition mechanism is discussed. 相似文献
143.
Relating Glucosinolate Content and Flavor of Broccoli Cultivars 总被引:4,自引:0,他引:4
H.-Y. Baik J.A. Juvik E.H. Jeffery M.A. Wallig M. Kushad B.P. Klein 《Journal of food science》2003,68(3):1043-1050
144.
Taxonomy, ecology and antibiotic resistance of enterococci from food and the gastro-intestinal tract 总被引:10,自引:0,他引:10
Klein G 《International journal of food microbiology》2003,88(2-3):123-131
Apart from genotypic identification methods, there is a need for reliable conventional phenotypic identification schemes for simple and rapid determination of enterococcal species in food or in the gastro-intestinal tract (GIT). Only a limited number of enterococcal species is of importance for the ecology of the GIT or the food microflora, including E. faecalis, E. faecium, E. durans/hirae, E. gallinarum and E. casseliflavus. After genus identification the differentiation within these species can include, e.g. mannitol and arabinose fermentation and growth at 50 degrees C. Widely used commercial identification systems may fail to precisely identify rare species. Ecological aspects should also be taken into account. In the human GIT E. faecium is the most common species whereas in most animal species E. faecalis is at least present in the same amount. Especially in foods of animal origin (cheese, pork meat, beef, poultry meat) also E. faecalis is very frequent. This is of special interest as glycopeptide resistance is most often found in human clinical E. faecium strains as well as in E. faecium from the environment or animal samples and less frequent in E. faecalis strains. EU experts propose as safety criteria for probiotics in feed additives the exclusion of resistances or the lack of transferability. This proposal can also be applied to enterococci in foods. Specific resistances must be excluded, but transferability or acquisition of resistance (e.g. vancomycin) cannot be excluded per se. However, technologically used strains should differ from clinical strains concerning their resistance patterns and transfer rates. 相似文献
145.
Physicochemical,crystallinity, pasting and thermal properties of heat‐moisture‐treated pinhão starch
Vnia Zanella Pinto Nathan Levien Vanier Bruna Klein Elessandra da Rosa Zavareze Moacir Cardoso Elias Luiz Carlos Gutkoski Elizabete Helbig Alvaro Renato Guerra Dias 《Starch - St?rke》2012,64(11):855-863
The effect of heat‐moisture treatment (HMT) on the properties of pinhão starches under different moisture and heat conditions was investigated. The starches were adjusted to 15, 20 and 25% moisture levels and heated to 100, 110 and 120°C for 1 h. The X‐ray diffractograms, swelling power, solubility, gel hardness, pasting properties and thermal properties of the native and HMT pinhão starches were evaluated. Compared to native starch, there was an increase in the X‐ray intensity and gel hardness of HMT starches, with the exception of the 25% moisture‐treated and 120°C heat‐treated starch. HMT reduced the swelling power and solubility of the pinhão starches when compared to native starch. There was an increase in the pasting temperature, final viscosity and setback and a decrease in the peak viscosity and breakdown of HMT pinhão starches compared to native starch. HMT increases the gelatinisation temperature of native pinhão starch and reduces gelatinisation enthalpy. 相似文献
146.
Jolanta Światowska-Mrowiecka Vincent Maurice Sandrine Zanna Lorena Klein Emrick Briand Ian Vickridge Philippe Marcus 《Journal of power sources》2007
Cyclic voltammetry, XPS, RBS and AFM have been combined to study the ageing mechanism of Li intercalation in V2O5 thin films prepared by thermal oxidation of vanadium metal. Multi-cycling tests were performed in 1 M LiClO4-PC in the potential range E ∈ [3.8, 2.8 V] versus Li/Li+, corresponding to the α-to-δ phase transition. XPS and AFM were performed using direct anaerobic and anhydrous transfer. Capacity fading remains inferior to 20% during ∼2500 cycles. XPS shows slight modifications of the oxide composition with a V4+ concentration increasing from ∼5% prior to cycling to ∼16–27% after cycling, due to Li trapped in the oxide film and to the loss of V2O5 active material. The presence of lithium carbonate and lithium-alkyl carbonate species evidences the formation of the so-called SEI layer. AFM evidences the loss of crystalline material by grain exfoliation from the outer V2O5 layer of the oxide film. By further exfoliation, the inner VO2 layer of the oxide film is reached and pits are formed, occupying ∼9–13% of the surface. This de-cohesion at grain boundaries is attributed to the strain generated by repeated lattice distortions. After 3300 cycles, the disappearance of lithium carbonates, whereas Li-alkyl carbonates and/or Li-alkoxides remain on the surface, indicates the dissolution and/or conversion of the SEI layer. After 4500 cycles, the oxide film became very labile and could be stripped away by rinsing to reveal the vanadium metal substrate. 相似文献
147.
148.
149.
Robert Schafranek Andre Giere Adam G. Balogh Thorsten Enz Yuliang Zheng Patrick Scheele Rolf Jakoby Andreas Klein 《Journal of the European Ceramic Society》2009,29(8):1433-1442
Barium strontium titanate (BST) thin films are studied with respect to their application as tunable dielectric at microwave frequencies. BST thin films are deposited by means of radio-frequency magnetron sputtering on platinized Si substrates. The substrate to target distance during sputter deposition is varied and the effect on structure, topology, composition and electronic properties is monitored using X-ray diffraction, atomic force microscopy, Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy. These findings are related to the dielectric measurements, which are carried out at 1 MHz and in the microwave range up to 8 GHz using metal-insulator-metal structures with Pt electrodes. For further device evaluation, leakage current measurements are carried out. Changing the process parameter strongly affects the composition of the films. The results emphasize the possibility for enhancing the microwave properties by fine-tuning of the chosen process parameter. 相似文献
150.
A. Girginov A. Zahariev E. Klein 《Journal of Materials Science: Materials in Electronics》2002,13(9):543-548
The electronic conductivity, i.e. the leakage current of aluminum electrolytic capacitors having as a dielectric a complex anodic film with a defined thickness of the barrier sublayer is measured. The complex films are obtained by re-anodization in a non-dissolving electrolyte of porous alumina films formed in H2SO4 and in (COOH)2. Analogous investigations with barrier-type anodic films are carried out for comparison. It is found that in all cases the empirical dependence of the electronic current on field strength, Je=e exp(eE1/2), is valid for the investigated system. The constants e, and e are determined experimentally. Calculations based on the theory are performed to obtain theoretical values of the constant e, and they are compared with the experimental values. A satisfactory coincidence is obtained between the experimental data and those calculated on the base of the theory. Capacitors with complex films having different porous matrices are studied. The capacitors with a porous matrix formed in oxalic acid show a lower leakage current than those with a matrix formed in sulfuric acid. 相似文献