全文获取类型
收费全文 | 213篇 |
免费 | 8篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 54篇 |
金属工艺 | 2篇 |
机械仪表 | 1篇 |
建筑科学 | 8篇 |
矿业工程 | 2篇 |
能源动力 | 5篇 |
轻工业 | 13篇 |
无线电 | 17篇 |
一般工业技术 | 35篇 |
冶金工业 | 30篇 |
原子能技术 | 3篇 |
自动化技术 | 47篇 |
出版年
2022年 | 4篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 8篇 |
2012年 | 18篇 |
2011年 | 13篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 9篇 |
2007年 | 7篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 14篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有221条查询结果,搜索用时 15 毫秒
71.
Antioxidant Potential of Pea Beans (Phaseolus vulgaris L.) 总被引:1,自引:0,他引:1
ABSTRACT: Four bean varieties ( Phaseolus vulgaris L.) (white kidney, red pinto, Swedish brown, and black kidney) and their hull fractions were extracted with 80% acetone and evaluated for their phenolic contents and antiradical activities. Total phenolic content of bean hulls and whole seed extracts ranged from 6.7 to 270 and 4.9 to 93.6 mg/g extract as catechin equivalents, respectively. Trolox equivalent antioxidant capacity (TEAC) assay revealed that the antioxidant capacity of red, brown, and black whole seed extracts was in the same order of magnitude with little variation. TEAC values of red and brown whole seed extracts were superior to that of black whole seed extract. On the basis of the total phenolic content and TEAC values, it can be deduced that colored beans possess superior antioxidative activity compared with white beans. The hydrogen peroxide scavenging capacity of different bean extracts ranged from 58% to 67% at 50 ppm and 65% to 76% at 100 ppm. The corresponding superoxide radical scavenging capacity was 24% to 29% at 50 ppm and 53% to 60% at 100 ppm. The 2,2–diphenyl-1–picrylhydrazyl (DPPH) radical scavenging capacity of black bean whole seed extracts was 22% at 50 ppm, whereas the other extracts showed 100% scavenging of this radical at both 50 and 100 ppm levels. The hydroxyl radical scavenging capacities of the bean extracts at 50 and 100 ppm were 12% to 29% and 32% to 49%, respectively. All extracts used prevented human low-density lipoprotein (LDL) cholesterol oxidation by 61.4% to 99.9% at 2 to 50 ppm level as catechin equivalents. 相似文献
72.
Terrence F. Hutt Mark E. Herrington 《Journal of the science of food and agriculture》1985,36(11):1107-1112
A method using reverse phase thin layer and high performance liquid chromatography was developed to determine the level of the bitter principle occasionally found in zucchini (Cucurbita pepo L.). The system gave excellent separation with recovery rates of about 90% from spiked fruit. The bitter principle was confirmed by C13 NMR and mass spectrometry as cucurbitacin E glycoside which was present in concentrations in the order of 600mg kg?1 in bitter fruits. Bitterness was detected by a taste panel at cucurbitacin E glycoside concentrations of 1 mg kg?1 in aqueous solutions and 2 mg kg?1 in zucchini pulp. The method described should assist the screening for bitterness in commercial and breeding populations of zucchini. 相似文献
73.
Ozer Unal Terrence E. Mitchell Arthur H. Heuer 《Journal of the American Ceramic Society》1994,77(4):984-992
The microstructures of ZrO2 –20 wt% Y2 O3 thermal barrier coatings formed by electron beam-physical vapor deposition on a Nibase superalloy have been studied by transmission electron microscopy. The coating systems consist of several layers, including a superalloy substrate, a bond coat, an Al2 O3 scale, and the PVD coating. The overall ceramic thermal barrier coatings were characterized, with special emphasis being given to the α-Al2 O3 scale which forms between the bond coat and the ZrO2− Y2 O3 coating. The oxide scale exhibited various morphologies in different coating systems; the majority of the porosity formed in this region for all coatings. 相似文献
74.
75.
Van-Tan Truong Brian C. Ennis Terrence G. Turner Charles M. Jenden 《Polymer International》1992,27(2):187-195
The effect of dopants and level of doping on the thermal stability of polypyrrole at 90, 120 and 150°C in dry air and nitrogen was investigated by monitoring the decay of conductivity. Polymers doped with aromatic anions (p-toluene sulphonate and p-chlorobenzene sulphonate) exhibit better stability than polymers doped with an aliphatic anion (dodecyl sulphate). The conductivity decay appears to follow diffusion controlled kinetics. After an initial decrease in conductivity, polypyrrole doped with p-toluene sulphonate anion maintains a constant conductivity at 150°C in air for at least 4 weeks. Dedoping results in materials of lower conductivity but greater thermal stability. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were found to be useful techniques to characterize and investigate thermal stability. Oxidation of polypyrrole films, monitored by DSC, shows diffusion controlled kinetics. Although both oxidation and conductivity decay show typical diffusion kinetics, oxidation is a necessary but not sufficient condition for the decay. 相似文献
76.
Mining and modeling for a metropolitan Atlanta ozone pollution decision-making framework 总被引:1,自引:0,他引:1
Zehua Yang Victoria C. P. Chen Michael E. Chang Terrence E. Murphy Julia C. C. Tsai 《IIE Transactions》2007,39(6):607-615
In this paper, we present a Decision-Making Framework (DMF) for reducing ozone pollution in the metropolitan Atlanta region. High ground-level concentrations of ozone continue to be a serious problem in several US cities, and Atlanta is one of the most serious of these cases. In contrast to the “trial and error” approach utilized by state government decision-makers, our DMF searches for dynamic and focused control strategies that require a lower total reduction of emissions than current control strategies. Our DMF utilizes a rigorous stochastic dynamic programming formulation and includes an Atmospheric Chemistry Module to represent how ozone concentrations change over time. This paper focuses on the procedures within the Atmospheric Chemistry Module. Using the US EPA's Urban Airshed Model for Atlanta, we use mining and metamodeling tools to develop a computationally efficient representation of the relevant ozone air chemistry. The proposed approach is able to effectively model changes in ozone concentrations over a 24-hour period. 相似文献
77.
Meyer TR Roy S Anderson TN Miller JD Katta VR Lucht RP Gord JR 《Applied optics》2005,44(31):6729-6740
Diode-laser-based sum-frequency generation of ultraviolet (UV) radiation at 313.5 nm was utilized for high-speed absorption measurements of OH mole fraction and temperature at rates up to 20 kHz. Sensor performance was characterized over a wide range of operating conditions in a 25.4 mm path-length, steady, C2H4-air diffusion flame through comparisons with coherent anti-Stokes Raman spectroscopy (CARS), planar laser-induced fluorescence (PLIF), and a two-dimensional numerical simulation with detailed chemical kinetics. Experimental uncertainties of 5% and 11% were achieved for measured temperatures and OH mole fractions, respectively, with standard deviations of < 3% at 20 kHz and an OH detection limit of < 1 part per million in a 1 m path length. After validation in a steady flame, high-speed diode-laser-based measurements of OH mole fraction and temperature were demonstrated for the first time in the unsteady exhaust of a liquid-fueled, swirl-stabilized combustor. Typical agreement of approximately 5% was achieved with CARS temperature measurements at various fuel/air ratios, and sensor precision was sufficient to capture oscillations of temperature and OH mole fraction for potential use with multiparameter control strategies in combustors of practical interest. 相似文献
78.
Benzyl phenyl ether (BPE) is a reactive organic oxygenate which contains the ether functionality believed to be present in subbituminous and bituminous coals. With an of 0.92 it has a ratio similar to that found in bituminous coals. Benzyl phenyl ether reacts readily at 375 °C either in the presence or absence of added donor hydrogen sources. The major products are toluene and phenol. Other, heavier products are also produced in significant quantities. In general, as available donor hydrogen is reduced, the products tend to have higher molecular weights. Conventional pyrolysis products become lighter (more desirable) materials when the pyrolysis is carried out in the presence of added hydrogen. 相似文献
79.
Terrence M. Grady Charles R. Heisler Clifton Blincoe 《Journal of the science of food and agriculture》1978,29(3):207-212
Manganese in lucerne (Medicago sativa L.) exists as a cationic complex of low molecular weight. It migrates as a single band on paper electrophoresis, cation exchange chromatography and gel exclusion chromatography. It exhibits no strong association with protein. The complex tends to be unstable in alkaline solution. 相似文献
80.
Collins TJ 《Accounts of chemical research》2002,35(9):782-790
In the Institute for Green Oxidation Chemistry, we develop oxidation catalysts with useful lifetimes via an iterative design process in which oxidation-sensitive ligand groups are identified and replaced. The process has led to catalysts with greatly enhanced stability toward oxidative and hydrolytic degradation. The iron catalysts described herein can be comprised exclusively of biochemically common elements. They are efficient and selective peroxide activators for many areas of technology. They are water-soluble and are effective in minute quantities (nanomolar to low micromolar) over a broad pH range. Various green chemistry applications are sketched. 相似文献