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排序方式: 共有249条查询结果,搜索用时 15 毫秒
91.
92.
Prediction of damage to water supply lines during an earthquake is a critical part of seismic planning. This study evaluates the performance of the water supply system in Denizli, Turkey, in the event of an M6, M6.3, M6.5 and M7 earthquake associated with the Pamukkale and Karakova-Akhan Faults. The relative effects of transient ground deformations and permanent ground deformations based on maps of liquefiable soil and zones of predicted lateral ground displacements are compared. The relative effects of the different magnitude earthquakes and pipeline damage relationships on the pipeline performance following a seismic event are assessed.  相似文献   
93.
94.
The present study reports the pervaporative separation capability of the pristine and polyhedral oligomeric silsesquioxanes (POSS) loaded hybrid polyether‐block ‐amide (PEBA) membranes for n ‐butanol recovery from the dilute n ‐butanol–water mixtures. It is the first study to produce POSS‐loaded PEBA membranes for n ‐butanol recovery. The morphology and crosslinking structure of the pristine and hybrid membrane were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The thermal stability and crystallization behaviors of the pristine and hybrid membranes were investigated using thermogravimetric analysis and differential scanning calorimetry methods. Swelling experiments were also done to determine the affinity of the membranes to the n ‐butanol–water mixture. The effect of increasing amount of POSS on pervaporation performance was investigated in terms of flux and the n ‐butanol separation factor at 40 °C and a given n ‐butanol. All the hybrid membranes exhibited high flux and n ‐butanol separation factor than that of the pristine PEBA membrane. The best n ‐butanol separation factor of 27.2 was obtained accompanied with 1.33 Kg m?2 h?1 of flux, when the POSS amount was 4 wt %. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45211.  相似文献   
95.
Poly(glycidylmethacrylate), p(GMA), brush grafted poly(vinylbenzyl chloride/ethyleneglycol dimethacrylate), p(VBC/EGDMA), beads were prepared by suspension polymerization and the beads were grafted with poly(glycidyl methacrylate), p(GMA), via surface‐initiated atom transfer radical polymerization aiming to construct a material surface with fibrous polymer. The epoxy groups of the fibrous polymer were reacted with hydrazine (HDZ) to create affinity binding site on the support for adsorption of protein. The influence of pH, and initial invertase concentration on the immobilization capacity of the p(VBC/EGDMA‐g‐GMA)‐HDZ beads has been investigated. Maximum invertase immobilization onto hydrazine functionalized beads was found to be 86.7 mg/g at pH 4.0. The experimental equilibrium data obtained invertase adsorption onto p(VBC/EGDMA‐g‐GMA)‐HDZ affinity beads fitted well to the Langmuir isotherm model. It was shown that the relative activity of immobilized invertase was higher than that of the free enzyme over broader pH and temperature ranges. The Km and Vmax values of the immobilized invertase were larger than those of the free enzyme. After inactivation of enzyme, p(VBC/EGDMA‐g‐GMA)‐HDZ beads can be easily regenerated and reloaded with the enzyme for repeated use. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   
96.
The transport properties of single-strand DNA probe-modified self-propelling micromachines are exploited for "on-the-fly" hybridization and selective single-step isolation of target nucleic acids from "raw" microliter biological samples (serum, urine, crude E. coli lysate, saliva). The rapid movement of the guided modified microrockets induces fluid convection, which enhances the hybridization efficiency, thus enabling the rapid and selective isolation of nucleic acid targets from untreated samples. The integration of these autonomous microrockets into a lab-on-chip device that provides both nucleic acid isolation and downstream analysis could thus be attractive for diverse applications.  相似文献   
97.
α-Amylase (EC 3.2.1.1; α-d-1,4,glucan glucanohydrolase) catalyzes the hydrolysis of α-d-(1,4)-glucosidic linkages in starch, glycogen, and various malto-oligosaccharides, by releasing α-anomeric products. In this study, a novel method has been developed to prepare nanoprotein particles that carry α-amylase as a monomer by using a photosensitive microemulsion polymerization process. The nanostructured α-amylase with photosensitive features have been characterized by fluorescence spectroscopy, transmission electron microscopy (TEM) and Zeta Sizer. The fluorescence intensity of amylase nanoparticles was determined to be 658 a.u. at 610 nm and the average particle size of nanoamylase was found to be about 71.8 nm. Both free α-amylase and nanoparticles were used in the hydrolysis of starch under varying reaction conditions such as pH and temperature that affect enzyme activity and the results were compared to each other. Km values were 0.26 and 0.87 mM and Vmax values were 0.36 IU mg? 1 and 22.32 IU mg? 1 for nanoenzyme and free enzyme, respectively. Then, thermal stability, storage stability and reusability were investigated and according to the results, activity was preserved 60% at 60 °C; 20% at 70–80 °C temperature values and 80% after 105 days storage. Finally after 10 cycles, the activity was preserved 90% and this novel enzymatic polymeric amylase nanoparticle has showed considerable potential as reusable catalyst.  相似文献   
98.
The applicability of Fenton's oxidation to improve the biodegradability of a pharmaceutical wastewater to be treated biologically was investigated. The wastewater was originated from a factory producing a variety of pharmaceutical chemicals. Treatability studies were conducted under laboratory conditions with all chemicals (having COD varying from 900 to 7000 mg/L) produced in the factory in order to determine the operational conditions to utilize in the full-scale treatment plant. Optimum pH was determined as 3.5 and 7.0 for the first (oxidation) and second stage (coagulation) of the Fenton process, respectively. For all chemicals, COD removal efficiency was highest when the molar ratio of H(2)O(2)/Fe(2+) was 150-250. At H(2)O(2)/Fe(2+) ratio of 155, 0.3M H(2)O(2) and 0.002 M Fe(2+), provided 45-65% COD removal. The wastewater treatment plant that employs Fenton oxidation followed by aerobic degradation in sequencing batch reactors (SBR), built after these treatability studies provided an overall COD removal efficiency of 98%, and compliance with the discharge limits. The efficiency of the Fenton's oxidation was around 45-50% and the efficiency in the SBR system which has two reactors each having a volume of 8m(3) and operated with a total cycle time of 1 day, was around 98%, regarding the COD removal.  相似文献   
99.
Enhancement of a gain-sensitivity analysis of electrical networks is presented by computing gain sensitivities with respect to network parameters. A simple and versatile method. The so-called chain-sensitivity matrix is presented and compared with the current method in the literature, gain factorization, for the gain sensitivities of the cascaded networks. Analytical formulas are derived to calculate gain sensitivities of the T and Π types of distributed-parameter amplifiers with respect to the physical length l and characteristic impedance Z0, rather than using a time-intensive computer-based perturbation method. The numerical results of the T- and Π-type amplifiers for the design targets of noise figure Freq = 0,46 dB (⇔ 1, 12) input VSWR Vireq = 1, power gain GTreq = 12 dB (⇔ 15, 86) and the bandwidth B = 2 GHz − 11 GHz are given in comparison to each other. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14: 462–474, 2004.  相似文献   
100.
In this work, synthesis of linear array geometry and excitation amplitudes is first formulated as a linearly constrained multiobjective optimization problem with the goals of minimum sidelobe level, null control and high directivity and then solved by a generalized pattern search (GPS) algorithm for the optimum element locations and excitation amplitudes. The constraints are imposed on the interelement spacing and dynamic range ratio of the amplitude tapering to reduce mutual coupling effects between the elements. GPS methods are newly discovered, derivative‐free methods where the current iterate is updated by sampling the fitness function at a finite number of points along a suitable set of search directions to find a decrease in the function value. Thus, GPS methods can be exploited efficiently in solving optimization problems without requiring any information about the gradient of the fitness function which may be even discontinuous, nondifferentiable, stochastic or highly nonlinear. Finally, four worked examples are presented that illustrate the use of the whole GPS synthesis method, and the optimization goal in each example is easily achieved. Furthermore the full‐wave simulations of the synthesized arrays are also completed to examine the mutual coupling effects. Finally the results of the GPS algorithm are validated by comparing with results obtained using the genetic algorithm, and the results of the uniform and Dolph ‐ Chebyshev arrays, having the same number of element and the same aperture length. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.  相似文献   
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