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1.
Tensile testing of a modified 9Cr–1Mo steel in two microstructural conditions (710T– normalized at 1100°C, tempered at 710°C, and 550T – normalized at 1100°C tempered at 550°C) in the temperature range 25–450°C, under strain rates of 2.3×10-5–2.3×10-3s-1, exhibited serrated flow curves, with serrations appearing almost at the onset of deformation and disappearing before ultimate strengths were attained. The serrated flow curves (characteristics of dynamic strain ageing) were accompanied by increased ultimate strengths, loss of ductility and negative strain-rate sensitivity, relative to the ambient temperature properties. However, the increase in ultimate strength and the reduction in ductility were much larger for 710T specimens, as compared to 550T ones. In the dynamic strain ageing regime, the work-hardenability of 710T specimens increased rapidly while that of 550T specimens remained practically unaffected. Based on the microstructural consideration and the observed activation energy of 45 kJ mol-1, it is proposed that serrations are initiated by a nitrogen atmosphere formation on the waiting dislocations by a pipe diffusion mechanism, and they disappear by diffusion to the precipitate sinks during deformation. Because the fine alloy carbide precipitates in 550T specimens are more effective sinks than those of 710T ones, they can cause much faster depletion of the atmosphere, resulting in a much smaller effect of dynamic strain ageing on the tensile properties of 550T specimens. 相似文献
2.
SHELF-LIFE MODELING OF SWEETENED CONDENSED MILK BASED ON KINETICS OF MAILLARD BROWNING 总被引:1,自引:0,他引:1
A. A. PATEL H. GANDHI SUDHIR SINGH G. R. PATIL 《Journal of Food Processing and Preservation》1996,20(6):431-451
Nonenzymatic browning and related changes were monitored in commercial sweetened condensed milk stored at 7, 15, 30, 45 and 55C. Darkening of the color measured in terms of absorbance (100 - reflectance percent) followed zero-order kinetics, the apparent activation energy (Ea ) being 45.2 kJ/mol at 7–30C and 139.9 kJ/mol at > 30–55C. Hydroxy-methyl-furfural (HMF) showed a first-order increase, the associated Ea values being smaller than those for absorbance. The pH exhibited a linear decline after a small initial rise at 30C and below. As browning progressed, the coffee whitening ability of the product decreased along zero-order kinetics. The Q10 values for these variables ranged from 1.21 to 1.84 for temperatures up to 30C and were nearly 2–3 times higher above 30C. The sensory color score was negatively correlated with absorbance. The linear regression of color score on absorbance and the temperature dependence of the latter as expressed by Arrhenius relationship were combined into a mathematical model which could be useful in predicting the product's shelf-life. 相似文献
3.
SIMULATION OF THAWING OF FOODS USING FINITE ELEMENT METHOD 总被引:2,自引:0,他引:2
4.
YOUSSEF S. HAFEZ ALI I. MOHAMED GURBAX SINGH FAWZY M. HEWEDY 《Journal of food science》1985,50(5):1271-1274
Two hundred grams of soybean seeds (moisture contents of 7.4, 15.3, 22.5, and 30.5%) were irradiated at dose levels of 0, 1, 5, 10, 20, 40, 60, 80 and 100 KGy using Cobalt-60 source. Radiation dose of 100 KGy caused a decrease in the percentage of nitrogen solubility from 80.3 to 67.2, 80.3 to 57.8, and 68.1 to 48.8 when deionized H2O, 0.6M NaCl, and 0.2M Cacl2 were used as solvents, respectively. Inhibition of 71% of lipoxygenase activities, 25.4% trypsin inhibitor activities, and 16.7% chymotrypsin inhibitor activities were found when the soybean seeds were irradiated at 100 KGy. 相似文献
5.
Experimental residence-time distribution (RTD) characteristics of an extrusion process may be used to estimate the extent of mixing experienced in the extruder. Using earlier theories of laminar mixing and striation thickness reduction, a new approach to estimate efficacy of mixing of two phases in the mixing zone of the extruder is proposed. Predicting the time required to achieve complete mixing and comparing it with the minimum time (plug flow time) that the extrudate spends in the mixing zone gives a ratio that can be used to evaluate the adequacy of extruder operating conditions for good mixing of gas/fluid injection and extrudate. Twin-screw extrusion of cornmeal with carbon dioxide injection were used to investigate the effect of CO2 injection pressure and extruder screw speeds on mixing. Lower CO2 injection pressures (25 bars) and lower screw speeds (150 rpm) were theoretically shown to enhance mixing. Scanning electron micrographs (SEMs) of experimental samples taken showed smaller and more uniform cell structures for those conditions which were predicted to favor better mixing. 相似文献
6.
Manpreet Singh UCOE Manjeet Singh Patterh UCOE 《Information Security Journal: A Global Perspective》2013,22(6):332-343
ABSTRACT It is difficult to define reliable security policy components that should be applied to validate a secure computing environment. The job gets further complicated when one has to deal with multiple policies in single computing environment. This paper demonstrates how we can overcome the difficulties of defining reliable security components by using evaluation criteria. In this paper we use common criteria to derive the security functional components for a multipolicy-based network computing environment. In the verification process, the derived policy components are related to the specific security objectives of the network communication environment. The evidence listed in the case study supports the claims that the proposed network security policy interpretation framework is a complete and cohesive set of requirements. 相似文献
7.
Traditional clustering algorithms are inapplicable to many real-world problems where limited knowledge from domain experts
is available. Incorporating the domain knowledge can guide a clustering algorithm, consequently improving the quality of clustering.
In this paper, we propose SS-NMF: a semi-supervised non-negative matrix factorization framework for data clustering. In SS-NMF,
users are able to provide supervision for clustering in terms of pairwise constraints on a few data objects specifying whether
they “must” or “cannot” be clustered together. Through an iterative algorithm, we perform symmetric tri-factorization of the
data similarity matrix to infer the clusters. Theoretically, we show the correctness and convergence of SS-NMF. Moveover,
we show that SS-NMF provides a general framework for semi-supervised clustering. Existing approaches can be considered as
special cases of it. Through extensive experiments conducted on publicly available datasets, we demonstrate the superior performance
of SS-NMF for clustering.
相似文献
Ming DongEmail: |
8.
In this paper, device performance of graphene nanoribbon field effect transistor (GNRFET) with different doping concentrations in different parts of the channel is reported. The study is performed by using atomistic simulations based on self-consistent solution of Schrodinger’s and Poisson’s equation within the non-equilibrium Green’s function formalism. The transfer and output characteristics suggest that device performance with n-type doping in the channel is better with smaller supply voltage compared to higher supply voltage. On increasing the n-type doping concentration, we obtained better on-current and output characteristics in comparison with undoped and p-type doped channel GNRFET. Further, we introduced step-doping profile in the graphene nanoribbon (GNR) channel and found that the device gives better on-current and good saturation condition when compared to undoped or uniformly-doped channel. 相似文献
9.
A two-phase framework for quality-aware Web service selection 总被引:1,自引:0,他引:1
Qi Yu Manjeet Rege Athman Bouguettaya Brahim Medjahed Mourad Ouzzani 《Service Oriented Computing and Applications》2010,4(2):63-79
Service-oriented computing is gaining momentum as the next technological tool to leverage the huge investments in Web application
development. The expected large number of Web services poses a set of new challenges for efficiently accessing these services.
We propose an integrated service query framework that facilitates users in accessing their desired services. The framework
incorporates a service query model and a two-phase optimization strategy. The query model defines service communities that
are used to organize the large and heterogeneous service space. The service communities allow users to use declarative queries
to retrieve their desired services without worrying about the underlying technical details. The two-phase optimization strategy
automatically generates feasible service execution plans and selects the plan with the best user-desired quality. In particular,
we present an evolutionary algorithm that is able to “co-evolve” multiple feasible execution plans simultaneously and allows
them to compete with each other to generate the best plan. We conduct a set of experiments to assess the performance of the
proposed algorithms. 相似文献
10.
Data co-clustering refers to the problem of simultaneous clustering of two data types. Typically, the data is stored in a
contingency or co-occurrence matrix C where rows and columns of the matrix represent the data types to be co-clustered. An entry C
ij
of the matrix signifies the relation between the data type represented by row i and column j. Co-clustering is the problem of deriving sub-matrices from the larger data matrix by simultaneously clustering rows and
columns of the data matrix. In this paper, we present a novel graph theoretic approach to data co-clustering. The two data
types are modeled as the two sets of vertices of a weighted bipartite graph. We then propose Isoperimetric Co-clustering Algorithm
(ICA)—a new method for partitioning the bipartite graph. ICA requires a simple solution to a sparse system of linear equations
instead of the eigenvalue or SVD problem in the popular spectral co-clustering approach. Our theoretical analysis and extensive
experiments performed on publicly available datasets demonstrate the advantages of ICA over other approaches in terms of the
quality, efficiency and stability in partitioning the bipartite graph. 相似文献