全文获取类型
收费全文 | 279篇 |
免费 | 13篇 |
专业分类
化学工业 | 132篇 |
金属工艺 | 6篇 |
机械仪表 | 4篇 |
建筑科学 | 7篇 |
能源动力 | 4篇 |
轻工业 | 41篇 |
水利工程 | 3篇 |
石油天然气 | 4篇 |
无线电 | 9篇 |
一般工业技术 | 32篇 |
冶金工业 | 22篇 |
原子能技术 | 2篇 |
自动化技术 | 26篇 |
出版年
2023年 | 2篇 |
2022年 | 22篇 |
2021年 | 28篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 16篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 18篇 |
2012年 | 15篇 |
2011年 | 18篇 |
2010年 | 14篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 9篇 |
2006年 | 16篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1970年 | 3篇 |
1969年 | 3篇 |
排序方式: 共有292条查询结果,搜索用时 15 毫秒
101.
102.
Nataliya A. Vlasenko Pavel F. Oleksenko Ludmila I. Veligura Miroslav O. Mukhlyo Zinaida L. Denisova Viktor F. Zinchenko 《Journal of the Society for Information Display》2007,15(11):937-941
Abstract— The following main differences have been revealed in the characteristics of an edge thin‐film‐electroluminescent ZnS: Er,F emitter compared to those of a similar planar emitter: (1) the 1.535‐μm band more highly dominates over other bands in the EL spectrum; (2) the voltage (V) dependence of the intensity of this band is the strongest; (3) the 1.535‐μm band narrows with increasing voltage and its frequency. The above differences are explained, firstly, by smaller optical losses in the ZnS: Er,F film for the near‐infrared emission than for the visible one and, secondly, by an optical amplification over the 1.535‐μm band in the edge emitter. 相似文献
103.
Igor Goldfarb Vladimir Gol'dhstein J. Barry Greenberg Grigory Kuzmenko 《Journal of Engineering Mathematics》2002,44(3):229-243
Semenov's classical model of thermal explosion in a combustible gas mixture is modified to include radiative (rather than conductive) heat-loss effects and gas-density changes. A geometrical asymptotic technique (the method of integral manifolds - MIM) is exploited to perform a qualitative analysis of the governing equations. The strength of this method lies in the compact, clear geometrical/analytical rendition and classification of all possible dynamical scenarios, in terms of the physico-chemical parameters of the system. It is found that there are two main dynamical regimes of the system: cooling regimes and fast explosive regimes. Peculiarities of these dynamical regimes are investigated and their dependence on physical system parameters is analyzed. A criterion for the occurrence of thermal explosion is disclosed. An estimate for the maximum mixture temperature is also derived analytically. It is found that, under certain operating conditions, the dynamics are such that the initial explosive stage of the process essentially behaves adiabatically before succumbing to the dominance of the radiative heat loss that brings the system down to the ambient temperature. 相似文献
104.
Chen W Poullet E Burie J Boucher D Sigrist MW Zondy JJ Isaenko L Yèlisseyev A Lobanov S 《Applied optics》2005,44(19):4123-4129
The first demonstration, to the best of our knowledge, of continuous-wave (cw) difference-frequency generation (DFG) in LiInS2 crystal is reported. Wide spectral coverage (5.5-11.3 microm) has been obtained with angle and wavelength tuning for type II (eoe) critically phase-matched parametric interaction. The phase-matching conditions in cw DFG have been investigated, which allowed us to improve the Sellmeier parameters by use of a two-pole dispersion equation. An effective nonlinear coefficient deff = 6.9 +/- 0.8 pm/V has been determined at approximately 7 microm relative to the well-known nonlinear coefficient d36 of AgGaS2, which yields a power-conversion efficiency of approximately 12.4 microW/(W2 cm). We evaluated the high-resolution spectral characteristics of the DFG source by recording C2H2 and SO2 spectra. 相似文献
105.
Four strains of bottom brewer's yeast used in Czech breweries did not differ substantially from one another in their frequencies of spontaneous respiratory-deficient (RD) mutants as tested by the triphenyl tetrazolium chloride (TTC) overlay technique. These frequencies amounted to 1.1–1.4% of the total viable cell number after cultivation in bottom layers of wort. The strain which had the highest rate of aerobic growth gave a spontaneous mutation frequency of 0.5% in shaken cultures. In comparison with the TTC overlay technique, WL-Difco-agar with brom cresol green gave lower estimations of the frequency of production of spontaneous RD mutants. The RD mutants isolated can be divided into II groups on the basis of their cytochrome content (particularly cytochromes b and c) after aerobic growth. Of the 34 RD isolates tested, only 3 produced considerable numbers of revertants to respiratory sufficiency. These 3 mutants were derived from the same original strain, had the same cytochrome type, and had very slow growth rates. All RD mutants isolated had slower growth rates under aerobic conditions and reduced fermentation rates in static cultures in comparison with the parent types. 相似文献
106.
Ludmila Kilhnkov Josef Mostek Andla Pizingerov 《Journal of the Institute of Brewing》1975,81(3):218-224
Four industrial strains of bottom brewer's yeast and a group of their spontaneous respiration deficient (RD) mutants were tested for rates of metabolism of glucose and maltose under aerobic and anaerobic conditions. Qo2 of all the RD mutants tested (26 isolates) ranged from 1·9 to 6·8 μl/mg yeast dry weight on glucose and was lowered to about one-half on maltose although the original strains had the same Qo2 values on both sugars. No isolate showed any increase in glucose fermentation in aerobic conditions as compared with the original strains and the decrease of Pasteur effect found in certain isolates was always accompanied by a strong decrease of glycolysis in both aerobic and anaerobic conditions. Two mutants showed a strongly negative Pasteur effect, for their fermentation rates were higher in aerobic conditions than in anaerobic ones. Two other mutants showed a strong negative Pasteur effect only on maltose. The ratio of QN2CO2 on glucose in most mutants was significantly lower than in their parental strains. 相似文献
107.
A number of technology and workload trends motivate us to consider the appropriate resource allocation mechanisms and policies for streaming media services in shared cluster environments. We present MediaGuard – a model-based infrastructure for building streaming media services – that can efficiently determine the fraction of server resources required to support a particular client request over its expected lifetime. The proposed solution is based on a unified cost function that uses a single value to reflect overall resource requirements such as the CPU, disk, memory, and bandwidth necessary to support a particular media stream based on its bit rate and whether it is likely to be served from memory or disk. We design a novel, time-segment-based memory model of a media server to efficiently determine in linear time whether a request will incur memory or disk access when given the history of previous accesses and the behavior of the server's main memory file buffer cache. Using the MediaGuard framework, we design two media services: (1) an efficient and accurate admission control service for streaming media servers that accounts for the impact of the server's main memory file buffer cache, and (2) a shared streaming media hosting service that can efficiently allocate the predefined shares of server resources to the hosted media services, while providing performance isolation and QoS guarantees among the hosted services. Our evaluation shows that, relative to a pessimistic admission control policy that assumes that all content must be served from disk, MediaGuard (as well as services that are built using it) deliver a factor of two improvement in server throughput. 相似文献
108.
Ludmila I. Kuncheva David Martínez-Rego Kenneth S. L. Yuen David E. J. Linden Stephen J. Johnston 《Signal, Image and Video Processing》2014,8(5):913-922
Functional Magnetic Resonance Imaging serves to identify networks and regions in the brain engaged in various mental activities, represented as a set of voxels in the 3D image. It is important to be able to measure how similar two selected voxel sets are. The major flaw of the currently used correlation-based and overlap-based measures is that they disregard the spatial proximity of the selected voxel sets. Here, we propose a measure for comparing two voxel sets, called Spatial Discrepancy, based upon the average Hausdorff distance. We demonstrate that Spatial Discrepancy can detect genuine similarities and differences where other commonly used measures fail to do so. A simulation experiment was carried out where distorted copies of the same voxel sets were compared, varying the level of distortion. The experiment revealed that the proposed measure correlates better with the level of distortion than any of the other measures. Data from a 10-subject experiment were used to demonstrate the advantages of the Spatial Discrepancy measure in multi-subject studies. 相似文献
109.
Jan Paava Ilja Knésl Anna Vymazalová Ivan Vavín Ludmila Ivanovna Gurskaya Leonid Ruslanovich Kolbantsev 《Canadian Metallurgical Quarterly》2011,2(1)
The Polar Urals region of northern Russia is well known for large chromium(Cr)-bearing massifs with major chromite orebodies,including the Centralnoye I deposit in the Ray-lz ultramafic massif of the Ural ophiolite belt.New data on platinum(Pt)-group elements(PGE),geochemistry and mineralogy of the host dunite shows that the deposit has anomalous iridium(It)values.These values indicate the predom-inance of ruthenium-osmium-iridium(Ru-Os-lr)-bearing phases among the platinum-group mineral(PGM)assemblage that is typical of mantle-hosted chromite ores.Low Pt values in chromites and increased Pt values in host dunites might reflect the presence of cumulus PGM grains.The most abundant PGM tbund in the chromite is erlichmanite(up to 15 μm).Less common are cuproiridsite(up to 5 μm),irarsite(up to4-5 μm),and laurite(up to 4 μm).The predominant sulfide is heazlewoodite,in intergrowth with Ni--Fe alloys,sporadically with pentlandite,and rarely with pure nickel.Based on the average PGE values and esti-mated Cr-ore resources,the Centralnoye I deposit can be considered as an important resource of PGE. 相似文献
110.
Cold forming of high strength materials is accompanied by an undesirable spring-back effect and therefore the automotive industry prefers to produce components from high strength steels by hot stamping.Hot deformation and cooling in a die are applied to obtain shaped components with martensitic microstructure and high yield strength and ultimate tensile strength.This article presents new applications of this forming technology by incorporating another innovative heat treatment by the Q-P process,which improves both strength and ductility of obtained structures at the same time.Ultimate strengths over 2000 MPa with ductility above 10% can be achieved by this processing.To test microstructure development,thin sheet was hot formed and a corresponding FEM simulation was created.This processing was applied to low alloyed AHS steel with 0.42% of carbon and with an alloying strategy based on Mn,Si and Cr.Martensitic microstructure with retained austenite was obtained by this processing with a strength of around 2000 MPa and ductility of 10%. 相似文献