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951.
Third‐generation SiC fibers [High Nicalon S (HNS) and Tyranno SA3 (Ty–SA3)] were studied by X‐ray diffraction and transmission electron microscopy (TEM) after heat treatments in neutral atmosphere up to 1900°C. The microstructural changes in both materials were determined using a modified Hall–Williamson method introducing an anisotropy parameter taking into account the high density of planar defects. HNS fibers exhibit significant modifications in the coherent diffraction domains (CDD) size, which drastically increases from 24 to 70 nm in the range 1600°C–1900°C. TEM observations support these results. The residual microstrain values decrease from 0.0015 to 0.0005 between 1750°C and 1850°C. Similarly, the anisotropy parameter significantly decreases in the same temperature range. Concerning the Ty–SA3 fibers, no evolution in terms of CDD size and residual microstrain was observed. However, the anisotropy parameter decreases at 1800°C. TEM observations did not show noticeable grain growth. The grain size was found to be larger than the CDD and the planar defects density to decrease at high temperature. In both types of fibers, the CDD sizes are similar for the highest temperature heat treatments.  相似文献   
952.
In the leaching kinetics of roasted zinc concentrate in NaOH solution, during the early stage of the leaching process, the rate-determining step is diffusion through the zinc ferrite, while in the later stage, it is surface reaction on the zinc oxide. In the shrinking core model, diffusion through a solid layer can be the rate-determining step even in the early stage of the leaching process, not only in later stage. The solid layer changed from zinc ferrite to the porous iron oxide as leaching proceeded, and this substance then thickened progressively due to the selective dissolution of zinc ferrite.  相似文献   
953.
954.
A series of four fluorinated dipeptide analogues each containing a fluoro‐olefin moiety as peptide bond surrogate has been designed and synthesized. These motifs have been successfully introduced into the bioactive C‐terminal heptapeptide of the neuropeptide 26RFa by conventional SPPS. We then evaluated the ability of the generated pseudopeptides to increase [Ca2+]i in GPR103‐transfected cells. For these fluorinated analogues, greater stability in human serum was observed. Their conformations were also investigated, leading to the valuable identification of differences depending on the position of the fluoro‐olefin moiety in the sequence.  相似文献   
955.
There is now on the market a profusion of technological devices to build plants. These devices are standardized to facilitate their dissemination and integration. The standards are technology driven because they are mainly elaborated by vendors for the design and delivery of complex plants. Operating plants means to control, maintain and manage them. Plants are operated by skilled operators, whose knowledge is mainly acquired by experience and feedback. The aim of this paper is to pave the way to master the complexity of plant operation, through explicit representation, and to help operators improve safety, productivity and reduce environmental impact.  相似文献   
956.
The continuous hydrolysis of bovine haemoglobin at pH 3 in a triphasic reactor was studied in order to prepare two pure transient and hydrophobic opioid peptides in one step. A continuous stirred‐tank reactor was designed to extract continuously and selectively LVV‐haemorphin‐7 and VV‐haemorphin‐7 by a butan‐2‐ol–octan‐1‐ol mixture in the course of bovine haemoglobin hydrolysis by pepsin immobilised on A568 Duolite resin. The residence time in the aqueous and organic phases was maintained at 1 h. This system allowed a steady state to be achieved for haemorphin concentrations in each phase and the pepsin stability to be maintained. Finally, success was achieved in producing and extracting continuously the two haemorphins in the aqueous/butan‐2‐ol–octan‐1‐ol biphasic medium for more than 10 bed volumes of the reactor. Copyright © 2006 Society of Chemical Industry  相似文献   
957.
Denial of responsibility as a mode of dissonance reduction and the conditions under which it is likely to occur were explored in 3 experiments. Two experiments tested and supported the hypothesis that following a counterattitudinal behavior, participants prefer the mode of reduction made available to them first, regardless of whether it is attitude change, trivialization, or denial of responsibility. The 3rd experiment tested and supported the hypothesis that denial of responsibility reduces the negative affective state induced by dissonance. The mechanism of denial of responsibility in dissonance reduction is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
958.
数据关联是多目标跟踪的一个重要部分,作者对基于证据合成和简易JPDA的数据关联方法进行了比较。蒙特卡罗仿真结果表明,基于证据合成的方法可以改善跟踪精度,能适应目标数目不确定的场合。  相似文献   
959.
Of students who enroll in 4-year universities, 25% never finish. Precipitating causes of early departure include poor academic progress and lack of clear goals and motivation. In the present study, we investigated whether an intensive, online, written, goal-setting program for struggling students would have positive effects on academic achievement. Students (N = 85) experiencing academic difficulty were recruited to participate in a randomized, controlled intervention. Participants were randomly assigned to 1 of 2 intervention groups: Half completed the goal-setting program, and half completed a control task with intervention-quality face validity. After a 4-month period, students who completed the goal-setting intervention displayed significant improvements in academic performance compared with the control group. The goal-setting program thus appears to be a quick, effective, and inexpensive intervention for struggling undergraduate students. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
960.
During the last 5 years the European hot dry rock project (HDR) at Soultz-sous-Forêts (France) has made significant progress. Three approx. 5000-m deep wells have been drilled into the crystalline basement and hydraulically stimulated. These operations have provided a great deal of information on the subsurface, especially from the interpretation of the monitored induced microseismic events. To better understand the development and hydraulic behaviour of the fractured reservoir, a numerical model based on a discrete fracture network approach has been written to interpret and predict the pressure distribution in the HDR reservoir. The hydraulic part of this finite volume code is strongly coupled with the mechanical behaviour of the fractures.Recent modelling studies have demonstrated that the density difference between the in situ (native) reservoir fluid (density 1060 kg/m3) and the injected fluid (dense brine or fresh water) might play a significant role in the hydraulic stimulation of the reservoir. The decision was therefore taken to enhance the numerical code, under the assumption of immiscibility of the two fluids.The improved code permits us to evaluate the impact of fluid density differences on the pressure distribution in the reservoir during stimulation or fluid circulation tests. It provides better estimates on both the extension and shape of the stimulated areas, and can be used to define new stimulation strategies. The code has also been successful in predicting changes in fluid flow distributions in the reservoir, especially in fractures intersecting the wells, as well as in estimating trace breakthrough times.  相似文献   
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