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91.
Improved production of ginsenosides in suspension cultures of ginseng by medium replenishment strategy 总被引:1,自引:0,他引:1
The objective of this study was to improve the accumulation of ginsenosides by the adventitious root cultures of ginseng, which are important secondary metabolites with pharmaceutical applications. The adventitious roots were cultured in bioreactors for 50 d using 1.5-strength Murashige and Skoog (MS) medium supplemented with 10 mg/l indole acetic acid and 75 g/l sucrose. Kinetic studies of the nutrient composition of the spent medium revealed the gradual depletion of various inorganic nutrients and sugars. Cultures were supplied with fresh nutrient medium (medium exchange or replenishment with 0.75- and 1.0-strength MS medium) after 10 and 20 d of culture initiation to fulfill the nutritional requirements of adventitious roots. Medium replenishment strategy (with 1.0-strength MS medium after 20 d of culture) significantly improved the growth of adventitious roots and the biosynthesis of ginsenosides by the adventitious roots. This work is useful for the large-scale cultivation of adventitious roots for the production of ginsenosides. 相似文献
92.
J.-M. Yoon M.-H. Cho J.-E. Park Y.-H. Kim T.-R. Hahn Y.-S. Paik 《Journal of food science》2003,68(3):839-843
ABSTRACT Three major yellow pigments were isolated from safflower petals ( Carthamus tinctorius ) and characterized as hydroxysafflor yellow A (1), safflor yellow B (2), and precarthamin (3) by 1 H-NMR, 1 H-1 H COSY, 13 C-NMR, HMQC, and HMBC spectral analysis. Thermal degradation reactions of 3 yellow pigments 1 to 3 at temperatures of 70 to 90 °C were carried out at different pH levels within the range of 3.0 to 10.0 by UV-vis spectral measurements. First-order reaction kinetics was observed for the degradation of safflower yellow pigments (1 to 3) at pH 3.0 and 5.0. Activation energies of thermal degradation of 1-3 at pH 5.0 were calculated as 17.0, 15.4, and 20.1 kcal/mol, respectively. At neutral and alkaline conditions, yellow pigments 1-3 did not follow simple first-order kinetics. 相似文献
93.
A Nonlinear Structure Tensor with the Diffusivity Matrix Composed of the Image Gradient 总被引:1,自引:0,他引:1
We propose a nonlinear partial differential equation (PDE) for regularizing a tensor which contains the first derivative information
of an image such as strength of edges and a direction of the gradient of the image. Unlike a typical diffusivity matrix which
consists of derivatives of a tensor data, we propose a diffusivity matrix which consists of the tensor data itself, i.e., derivatives of an image. This allows directional smoothing for the tensor along edges which are not in the tensor but in
the image. That is, a tensor in the proposed PDE is diffused fast along edges of an image but slowly across them. Since we
have a regularized tensor which properly represents the first derivative information of an image, the tensor is useful to
improve the quality of image denoising, image enhancement, corner detection, and ramp preserving denoising. We also prove
the uniqueness and existence of solution to the proposed PDE. 相似文献
94.
There is typically a high degree of flexibility associated with the production of alternative fuels due to the ability to source from different input raw materials or to produce different output products based on market conditions. In this paper, we consider the particular example of ethanol and seek to quantify the incremental value from flexibility in its production from sugarcane in Brazil. We accomplish this by first jointly modeling the stochastic processes for the prices of the two relevant commodities, sugar (a food commodity) and ethanol (an energy commodity) in discrete time as a bivariate lattice. This framework allows us to value the option to switch output products based on the respective price signals of the two commodities. However, unlike the usual assumption of geometric Brownian motion stochastic processes, we use the more realistic case of mean reverting commodity price processes. We estimate the parameters for these processes by applying a regression-based procedure to empirical sugar and ethanol data collected during a period from 1998 through 2008. Our results show that the option to switch outputs has significant value, even under the assumption of mean reverting prices, which has implications for both producers and policy-makers alike. 相似文献
95.
M. Hahn 《Forschung im Ingenieurwesen》2009,73(2):77-86
For the consideration of released mass flows and their effects within hazard studies, leakage areas need to be determined which are physically justifiable and which cannot be reasonably excluded. Applying the fracture mechanics the leak-before-break behaviour is verified by the calculation of the propagation of an initial material defect. Consequently, leakage areas of through-cracks are calculated to determine probable and maximum leakage areas. For this purpose, models for the calculation of leak sizes are compared and evaluated. Example calculations are stated for typical pressurised vessels and pipes of the chemical industry in order to check the present estimates of leakage areas. In addition, measures supporting the leak-before-break behaviour are outlined. 相似文献
96.
A. Hahn 《e & i Elektrotechnik und Informationstechnik》2002,119(10):a6-a6
AktuellDivitec Metal
Aufbereitung von Elektro(nik)-Altger?ten 相似文献97.
As part of an overall investigation of flash-smelting processes, numerical computations were performed for the turbulent recirculating flow field of a gas jet in a confined cylindrical system. The two-equation (k - e) model was used to describe turbulence. The two-dimensional elliptic partial differential equations cast into finite difference forms were solved by the TEACH code (Gosman and Pun, 1973), and the pressure field was computed by the SIMPLER method (Patankar, 1980). Various correlations for the dissipation rate of turbulent kinetic energy at the inlet were tested, and the relation yielding the best results was obtained as E= CμK1.5/(0.015de where de = 4 x hydraulic radius. Extensive comparisons have been made between the computed results using the proposed form of e at the inlet and experimental data taken from the literature. Much better predictions than previously possible have been obtained 相似文献
98.
The random variability of fetal heart rate (FHR) is of practical importance in obstetric management. The variability is not white, however, and cannot be adequately described by its variance alone. We have modeled FHR variability as the scalar output of a multivariate, nonlinear stochastic process. An adaptation of the Kalman filter algorithm is used as part of an approximate maximum likelihood estimator of the process parameters. The filter algorithm permits recording artifacts to be disregarded, by treating them as "missing" observations. 相似文献
99.
100.
The results of 22 different investigations of cyclic crack growth, principally on the 2024-T3 and 7075-T6 alloys, but including results for unalloyed and other 2-, 5-, 6-, and 7-thousand series alloys have been examined and compiled with a view to separating metallurgical effects from other factors. The various crack growth measurements show good agreement when the comparisons involve the same , environment and cyclic frequency. Both the 2024-T3 and 7075-T6 alloy can display widely different rates of growth for the same . The highest growth rates are for tests in humid air, the lowest growth rates for tests in dehydrated air with high cyclic frequencies. These extremes point to a moisture assisted corrosion process capable of producing a 20-fold increase in the growth rate at low .Crack growth rate- measurements have also been converted into S-N curves for cracked members. These curves illustrate the influence of flaw size, stress range, and on the cyclic life of the 7075-T6 and 2024-T3 grades. The S-N curves show that the cyclic life of 2024-T3 is about 3 × that of 7075-T6 in laboratory air, about 5 × that of 7075-T6 in humidified air, and 10 × that of 7075-T6 if is in proportion to the yield strength. Finally, recent studies of the mechanisms of cyclic growth and other observations bearing on the contribution of metallurgical factors are examined. Effects associated with composition, heat treatment, small amounts of cold work, hard particles and inclusions, grain boundaries, the dislocation substracture produced by cyclic straining, and slip offsets are discussed. 相似文献