首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   734篇
  免费   26篇
  国内免费   4篇
电工技术   22篇
综合类   1篇
化学工业   131篇
金属工艺   7篇
机械仪表   36篇
建筑科学   35篇
能源动力   24篇
轻工业   24篇
水利工程   5篇
石油天然气   12篇
武器工业   1篇
无线电   61篇
一般工业技术   117篇
冶金工业   128篇
自动化技术   160篇
  2023年   11篇
  2022年   13篇
  2021年   25篇
  2020年   26篇
  2019年   26篇
  2018年   32篇
  2017年   20篇
  2016年   40篇
  2015年   26篇
  2014年   30篇
  2013年   51篇
  2012年   44篇
  2011年   58篇
  2010年   41篇
  2009年   36篇
  2008年   37篇
  2007年   29篇
  2006年   30篇
  2005年   21篇
  2004年   24篇
  2003年   19篇
  2002年   17篇
  2001年   23篇
  2000年   14篇
  1999年   12篇
  1998年   2篇
  1997年   7篇
  1996年   4篇
  1995年   3篇
  1994年   3篇
  1993年   4篇
  1992年   2篇
  1989年   2篇
  1988年   3篇
  1987年   1篇
  1986年   2篇
  1985年   2篇
  1983年   1篇
  1982年   4篇
  1981年   1篇
  1980年   2篇
  1978年   1篇
  1977年   1篇
  1975年   3篇
  1974年   2篇
  1973年   1篇
  1970年   2篇
  1969年   1篇
  1968年   1篇
  1966年   2篇
排序方式: 共有764条查询结果,搜索用时 15 毫秒
41.
Legumes are the base´s diet in several countries. They hold a high nutritional value, but other properties related to human health are nowadays being studied. The aim of this work was to study the influence of processes (boiling or germination) on the phenolic composition of dark beans (Phaseolus vulgaris L. c.v. Tolosana) and their effect on their antioxidant, neuroprotective and anticancer ability. Phenolic composition of raw and processed dark beans was analysed by HPLC-PAD and HPLC–ESI/MS. The antioxidant activity was evaluated by ORAC. Astrocytes cultures (U-373) have been used to test their neuroprotective effect. Anticancer activities were evaluated on three different cell lines (renal adenocarcinoma (TK-10), breast adenocarcinoma (MCF-7) and melanoma (UACC-62)) by sulphorhodamine B method. Qualitative and quantitative differences in phenolic composition have been observed between raw and processed dark beans that influence the antioxidant activity, mainly for germinated samples which show a decrease of antioxidant capacity. Although every assayed extracts decreased reactive oxygen species release and exhibited cytotoxicity activities on cancer cell lines, raw beans proved to be the most active in neuroprotective and antitumoral effects; this sample is especially rich in phenolic compounds, mainly anthocyanins. This study further demonstrated that phenolic composition of dark beans is related with cooking process and so with their neuroprotective and anticancer activity; cooking of dark beans improves their digestion and absorption at intestinal level, while maintaining its protective ability on oxidative process at cellular level.  相似文献   
42.
43.
Intergeneric protoplast fusants SK-26 and SK-35 between Saccharomyces cerevisiae ATCC 4126 and Kluyveromyces lactis CBS 683 produced 2.70 ml dl-1 and 1.52 ml dl-1 (v/v) of ethanol during fermentation of lactose at 25vv°C in salted Domiati cheese whey containing 6.1 g dl-1 (w/v) NaCl when entrapped in alginate spheres, whereas the free recombinant cells produced 2.36 ml dl-1 and 1.09 ml dl-1 (v/v) of ethanol. Yeast hybrids spheres can be used nine times with accumulated increases of ethanol production of 9.1 ml dl-1 and 8.98 ml dl-1 (v/v), respectively.  相似文献   
44.

Editorial Introduction

Guest Editorial: Flexible-Joint and Flexible-Link Robots  相似文献   
45.
46.
We propose a new burst scheduling mechanism for Optical Burst-Switched (OBS) networks. The new approach is made possible by gathering data bursts into groups and performing the scheduling decision for each group collectively. In OBS group-scheduling, bursts will not be considered for scheduling until a pre-defined time period elapses, during which the group of burst header packets would be gathered. By transforming a set of data bursts into a set of corresponding time intervals, the problem of scheduling these bursts is transformed into a combinatorial optimization problem. Graph algorithms are applied to obtain the maximum number of non-overlapping bursts. The proposed OBS group-scheduling scheme is shown to improve the performance of OBS networks over existing scheduling schemes in terms of burst loss probability and channel utilization. With an extension through a sequential optimization, using a Branch-and-Bound technique, the proposed scheme can support multiple classes of service. It is shown that the new scheduling approach has several desired characteristics including fairness and service differentiability among classes in terms of burst loss probability and channel utilization.  相似文献   
47.
This article describes RISCBOT (RISCBOT name has been derived from RISC lab and ‘bot’ of robot, a modular 802.11 b-enabled mobile autonomous robot built at the RISC lab of the University of Bridgeport. RISCBOT localizes itself and successfully fulfills www – enabled online user requests and navigates to various rooms, employing a visual recognition algorithm. This article describes the mechanical design, hardware and software algorithms of the robot, and the web-based interface for communicating with the robot. RISC lab: Interdisciplinary Robotics, Intelligent Sensing and Control laboratory at the University of Bridgeport.  相似文献   
48.
This paper presents the development and design of a robust linear controller for a flexible joint robot. First, a realistic model is developed taking into account the effects of stick-slip friction, nonlinear spring force characteristic, the rotors' Coriolis and centrifugal acceleration due to the velocities of the precedent links and rotors, and measurement noise. Second, a robust controller is designed using LQG/LTR techniques. Extensive simulation was performed on an experimental robot system using several trajectories. The results demonstrate that the proposed model/controller provides excellent tracking and regulation performance.  相似文献   
49.
A model introducing cohesive zones around material interfaces to simulate interfacial damage in microheterogeneous materials is developed. The material behavior within the cohesive zones is unknown a-priori, and is weakened, or "relaxed", on the continuum level from an initially undamaged state, by a reduction of the spatially variable elasticity tensor's eigenvalues. This reduction is initiated if constraints placed on the microstress fields, for example critical levels of pressure or deviatoric stresses, are violated. Outside of the cohesive zones the material is unaltered. Numerical computations are performed, employing the finite element method, to illustrate the approach in three dimensional applications.  相似文献   
50.
This study has been performed to relate the powder properties to the process parameters of the plasma-rotating-electrode-process (Prep). A regression equation for average powder diameter was acquired from the experimental data as . A model is developed to describe the nitrogen pick-up by the Prep. On the basis of this model an expression for nitrogen content of the powder produced is deduced as: The powder has a solidification structure of austenitic dendrites. The CrN precipitates, the amount of which is dependent upon the nitrogen content, can be found in the interdendritic areas. During the solution annealing the Cr2N precipitation reaction occurs in both of the inter- and intradendrite.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号