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101.
Ronald J. Jandacek Jeffrey J. Kester A. J. Papa Thomas J. Wehmeier Peter Y. T. Lin 《Lipids》1999,34(8):771-783
Olestra is a mixture of compounds comprising sucrose esterified with 6–8 long-chain fatty acids. It is not hydrolyzed by pancreatic
lipase and as a result is not absorbed from the small intestine. Olestra in general has physical properties similar to those
of a triacylglycerol with the same fatty acid composition. Foods made with olestra are virtually identical in taste and texture
to those made with typical triacylglycerols. Olestra consumption does not generate hydrolytic products in the small intestine
and, therefore, does not generate some of the signals that alter motility in the gastrointestinal tract. A reduction in gastroesophageal
reflux with olestra, in contrast to triacylglycerols, is consistent with a lack of effect on stomach emptying. Unlike triacylglycerols
that are absorbed in the proximal small intestine, olestra is distributed throughout the small intestine during transit and
passes into the colon. In the colon, olestra's effects depend on its physical properties. Liquid nondigestible lipids result
in separation of oil from the fecal matrix. Olestra formulations made with specific fatty acid compositions, particularly
those containing a solid sucrose polyester component including behenic acid, possess appropriate rheology to hinder separation
of oil from the rest of the fecal matrix, thereby reducing gastrointestinal symptoms. 相似文献
102.
103.
The UV spectra of tungsten oxide catalysts supported on alumina, titania and zirconia, and on titania–alumina and titania–zirconia
mixed oxides are reported and discussed. Evidence is provided for the different electronic structure of supports and catalysts,
which could affect the behavior of the tungsten oxide centres in the different cases. On alumina, tungsten oxide centres are
“isolated” by the insulating support, while on titania-based materials they are likely in electronic contact with each other
and with Ti centres through the support conduction band. In the case of WOx2013;ZrO2, the 5d levels of tungsten ions fall just below of the lower energy limit of the support conduction band.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
104.
Guido Schryen 《欧洲信息系统杂志》2013,22(2):139-169
The business value of investments in Information Systems (IS) has been, and is predicted to remain, one of the major research topics for IS researchers. While the vast majority of research papers on IS business value find empirical evidence in favour of both the operational and strategic relevance of IS, the fundamental question of the causal relationship between IS investments and business value remains partly unexplained. Three research tasks are essential requisites on the path towards addressing this epistemological question: the synthesis of existing knowledge, the identification of a lack of knowledge and the proposition of paths for closing the knowledge gaps. This paper considers each of these tasks. Research findings include that correlations between IS investments and productivity vary widely among companies and that the mismeasurement of IS investment impact may be rooted in delayed effects. Key limitations of current research are based on the ambiguity and fuzziness of IS business value, the neglected disaggregation of IS investments, and the unexplained process of creating internal and competitive value. Addressing the limitations we suggest research paths, such as the identification of synergy opportunities of IS assets, and the explanation of relationships between IS innovation and change in IS capabilities. 相似文献
105.
Summary. In this paper we introduce and analyze two new cost measures related to the communication overhead and the space requirements
associated with virtual path layouts in ATM networks, that is the edge congestion and the node congestion. Informally, the edge congestion of a given edge e at an incident node u is defined as the number of VPs terminating at or starting from u and using e, while the node congestion of a node v is defined as the number of VPs having v as an endpoint. We investigate the problem of constructing virtual path layouts allowing to connect a specified root node
to all the others in at most h hops and with maximum edge or node congestion c, for two given integers h and c. We first give tight results concerning the time complexity of the construction of such layouts for both the two congestion
measures, that is we exactly determine all the tractable and intractable cases. Then, we provide some combinatorial bounds
for arbitrary networks, together with optimal layouts for specific topologies such as chains, rings and grids.
Received: December 1997 / Accepted: August 2000 相似文献
106.
A single cohort of small individuals (31 mm mean shell length, 112 mg mean dry flesh weight) of the marine bivalve mollusc Mytilus galloprovincialis Lmk. was held sequentially for 2 wk at each of four food levels equivalent to ingested rations of less than 0.1%, 2.6%, 3.1%, and 7.4% of dry body weight per day. Growth rate reached a maximum at the highest ration level and was strongly correlated, amongst individuals, with mean heterozygosity measured across nine enzyme loci. Rates of energy expenditure were analysed separately as maintenance metabolic rate and the energy costs of growth (J mg-1 dry tissue). The maintenance metabolic rate correlated with traits of protein metabolism (protein synthesis, deposition, and breakdown), and the separate energy costs of both maintenance and growth correlated with the efficiency of protein deposition (protein growth as a proportion of synthesis). The energy costs of growth also varied in negative relation to mean individual heterozygosity. In a multiple regression analysis, the energy allocation to the costs of growth, body size, mean heterozygosity, and the efficiency of protein deposition together explained 90% of the variance amongst individuals in observed rates of growth. The results support the hypothesis that individual variability in the energy costs of protein turnover and in the efficiency of protein deposition during rapid growth are significant factors providing a link between individual genotype and its phenotypic expression as growth. 相似文献
107.
Guido Notermans Anco Heringa Maarten van Dort Sander Jansen Fred Kuper 《Microelectronics Reliability》2000,40(1):117
In this paper a new model for localized breakdown in NMOSTs under ESD stress is developed, which accounts for the reduced ESD strength in silicided devices. The model explains the impact of a stabilizing drain resistance on second breakdown current for both silicided and unsilicided protections. 相似文献
108.
Empirical evidence for effects of moods (both naturally occurring and experimentally manipulated) on behavior is reviewed in terms of an integrative theory: the mood-behavior model (MBM). It is posited that moods can influence behavior via 2 processes: (a) by informational effects on behavior-related judgments and appraisals, which in turn will result in behavioral adjustments (i.e., the informational mood impact on behavior), and (b) by influencing behavioral preferences and interests in compliance with a hedonic motive (i.e., the directive mood impact on behavior). The strength of the informational mood impact depends on moods' effective informational weight for behavior-related judgments and on mood-primed associations. The strength of the directive mood impact is predicted to be jointly determined by 2 variables: the strength of a hedonic motive and the instrumentality of possible acts for affect regulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
109.
110.
J. S. Major L. J. Guido N. Holonyak K. C. Hsieh E. J. Vesely D. W. Nam D. C. Hall J. E. Baker P. Gavrilovic K. Meehan W. Stutius J. E. Williams 《Journal of Electronic Materials》1990,19(1):59-66
In these experiments impurity-induced layer disordering (IILD) utilizing chemical reduction of SiO2 by Al (from Al0.8Ga0.2As) is employed to generate Si and O to effect layer disordering. The SiO2-Al0.8Ga0.2As reaction is studied with respect to annealing ambient. By controlling the extent of disordering via As4 overpressure, closely spaced (∼1μm) Si-O IILD buried heterostructure lasers can be optically coupled or uncoupled. Direct observation of O incorporation into
the buried layers is shown using secondary ion mass spectroscopy (SIMS). The thermal stability of separate-confinement AlyGa1−yAs-GaAs-InxGa1−xAs quantum well heterostructure (QWH) laser crystals is investigated using SIMS, transmission electron microscopy (TEM), and
photoluminescence (PL) measurements. The data show that the thermal stability of a strained-layer In0.1Ga0.9As quantum well (QW) is strongly dependent upon: (1) the layer thickness and heterointerfaces of the AlyGa1−yAs-GaAs waveguide layers located directly above and below the QW, (2) the type of surface encapsulant employed, and (3) the
annealing ambient. Narrow single-stripe (<2μm) lasers fabricated via Si-O diffusion and layer disordering exhibit low threshold currents (Ith ∼ 4 mA) and differential quantum efficiencies,η, of 22% per facet under continuous (cw) room-temperature operation. 相似文献