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   213篇
  免费   5篇
电工技术   2篇
化学工业   59篇
金属工艺   5篇
机械仪表   4篇
建筑科学   6篇
能源动力   8篇
轻工业   28篇
水利工程   3篇
无线电   6篇
一般工业技术   26篇
冶金工业   31篇
自动化技术   40篇
  2023年   1篇
  2022年   12篇
  2021年   7篇
  2020年   6篇
  2019年   8篇
  2018年   6篇
  2017年   6篇
  2016年   5篇
  2015年   5篇
  2014年   9篇
  2013年   17篇
  2012年   16篇
  2011年   12篇
  2010年   13篇
  2009年   3篇
  2008年   11篇
  2007年   4篇
  2006年   5篇
  2005年   2篇
  2004年   3篇
  2003年   2篇
  2002年   6篇
  2001年   3篇
  2000年   6篇
  1999年   1篇
  1998年   7篇
  1997年   1篇
  1996年   8篇
  1995年   5篇
  1994年   3篇
  1993年   4篇
  1991年   3篇
  1989年   2篇
  1988年   3篇
  1987年   1篇
  1986年   3篇
  1985年   1篇
  1984年   2篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1979年   1篇
  1975年   1篇
排序方式: 共有218条查询结果,搜索用时 15 毫秒
31.
32.
Gluten replacement in gluten‐free (GF) products presents major challenges for the food industry in terms of sensorial, technological and nutritional characteristics. The absence of gluten reportedly affects starch digestibility, thus increasing the postprandial glycaemic response. However, the role of ingredients and processing conditions has been addressed only seldom. We investigated the in vitro starch digestibility of 9 commercial GF products (5 Italian pasta and 4 Oriental noodles) differing in formulation and processing conditions. Content of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) were assessed and combined with information on starch pasting properties and on the overall protein organization. Oriental noodles presented higher relative levels of RS and RDS than Western‐style pasta, that often had SDS levels compatible with low rates of starch digestion. As regard formulation, presence of multiple ingredients seems to likely increase the RDS level, as did the different protein organization in the various samples.  相似文献   
33.
Analysis of the dynamic features of diffusion gradients in thin film devices (DGT) indicates that the penetration of complexes into the resin layer dramatically increases their lability. This should be taken into account when interpreting DGT measurements in terms of the dynamics of solution speciation. The experimental accumulation of Cd by DGT sensors in Cd-NTA systems confirmed these theoretical analyses. A computational code, which allows a rigorous digital simulation of the diffusion-reaction processes in the gel and resin layers, was used to model the results and to demonstrate the effect of the complex penetration into the resin layer on the lability degree. These findings suggest that DGT renders all complexes much more labile than if the resin-diffusive gel interface was considered as a perfect planar sink, explaining why DGT often measures a high proportion of the metal in a natural water. This information is relevant since some studies have stressed the importance of labile complexes as a source of bioaccumulated metal.  相似文献   
34.
The Journal of Supercomputing - The number of transmit and receiver antennas is an important factor that affects the performance and complexity of a MIMO system. A MIMO system with very large...  相似文献   
35.
An electronic business transaction among untrusted bodies without consulting a mutually trusted party has remained widely accepted problem. Blockchain resolves this problem by introducing peer-to-peer network with a consensus algorithm and trusted ledger. Blockchain originally introduced for cryptocurrency that came with proof-of-work consensus algorithm. Due to some performance issues, scientists brought concept of permissioned Blockchain. Hyperledger Fabric is a permissioned Blockchain targeting business-oriented problems for industry. It is designed for efficient transaction execution over Blockchain with pluggable consensus model; however, there is limitation of rapid application development. Hyperledger introduced a new layer called Hyperledger Composer on top of the Fabric layer, which provides an abstract layer to model the business application readily and quickly. Composer provides a smart contract to extend the functionality and flexibility of Fabric layer and provides a way of communication with other systems to meet business requirements. Hyperledger Composer uses role-based access control (RBAC) model to secure access to its valuable assets. However, RBAC is not enough because many business deals require continuous assets monitoring. Our proposed model, BlockU, covers all possible access control models required by a business. BlockU can monitor assets continuously during transactions and updates attributes accordingly. Moreover, we incorporate hooks in Hyperledger Composer to implement extended permission model that provides extensive permission management capability on an asset. Subsequently, our proposed enhanced access control model is implemented with a minimal change to existing Composer code base and is backward compatible with the current security mechanism.  相似文献   
36.
Polyfuran films doped with perchlorate anions (PFu/ClO4) were studied by scanning and transmission electron microscopies under different synthesis conditions. However, an electropolymerization overpotential equal to at least 2.1 V was needed to obtain stable PFu/ClO4 films. In the synthesis conditions analysed, the film growth face presented an ordered nodular structure oriented 45 ° with respect to the lengthwise axis of the electrode. The nodule size and film rugosity were affected by the ratios between furan and NaClO4 concentrations. When the furan concentration was double that of perchlorate, the films were less rough and more homogeneous. © 2000 Society of Chemical Industry  相似文献   
37.
In this study, four different fully formulated ISO VG 320 wind turbine gear oils were select: a mineral oil‐based, a polyalphaolefin‐based, an ester‐based and a polyalkyleneglycol‐based fluids. Their physical properties (viscosity, thermoviscosity, piezoviscosity etc.) were characterised for a wide range of operating temperatures. A two‐stage multiplying gearbox, with helical gears, was selected to evaluate the influence of the wind turbine gear oil formulation on torque loss with the gearbox operating at low speed (130–230 rpm) and high torque (500–1000 Nm). The results obtained showed that each wind turbine gear oil formulation generated very different torque losses, evacuated heat flows and operating temperatures, with differences above 20 °C under the most severe operating conditions. A numerical model was developed, simulating all power loss mechanisms inside the gearbox, in particular the churning and friction losses. The coefficients of friction, between gear teeth and between rolling elements and bearing raceways, were calculated for all the tested oils. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
38.
Small-scale gold mining in Portovelo-Zaruma, Southern Equador, performed by mercury amalgamation and cyanidation, yields 9-10 t of gold/annum, resulting in annual releases of around 0.65 t of inorganic mercury and 6000 t of sodium cyanide in the local river system. The release of sediments, cyanide, mercury, and other metals present in the ore such as lead, manganese and arsenic significantly reduces biodiversity downstream the processing plants and enriches metals in bottom sediments and biota. However, methylmercury concentrations in sediments downstream the mining area were recently found to be one order of magnitude lower than upstream or in small tributaries. In this study we investigated cyanide, bacterial activity in water and sediment and mercury methylation potentials in sediments along the Puyango river watershed, measured respectively by in-situ spectrophotometry and incubation with 3H-leucine and 203Hg2+.Free cyanide was undetectable (< 1 μg·L− 1) upstream mining activities, reached 280 μg·L− 1 a few km downstream the processing plants area and was still detectable about 100 km downstream. At stations with detectable free cyanide in unfiltered water, 50% of it was dissolved and 50% associated to suspended particles. Bacterial activity and mercury methylation in sediment showed a similar spatial pattern, inverse to the one found for free cyanide in water, i.e. with significant values in pristine upstream sampling points (respectively 6.4 to 22 μgC·mg wet weight− 1·h− 1 and 1.2 to 19% of total 203Hg·g dry weight− 1·day− 1) and undetectable downstream the processing plants, returning to upstream values only in the most distant downstream stations. The data suggest that free cyanide oxidation was slower than would be expected from the high water turbulence, resulting in a long-range inhibition of bacterial activity and hence mercury methylation. The important mercury fluxes resultant from mining activities raise concerns about its biomethylation in coastal areas where many mangrove areas have been converted to shrimp farming.  相似文献   
39.
Swimmers in nature use body undulations to generate propulsive and manoeuvring forces. The anguilliform kinematics is driven by muscular actions all along the body, involving a complex temporal and spatial coordination of all the local actuations. Such swimming kinematics can be reproduced artificially, in a simpler way, by using the elasticity of the body passively. Here, we present experiments on self-propelled elastic swimmers at a free surface in the inertial regime. By addressing the fluid–structure interaction problem of anguilliform swimming, we show that our artificial swimmers are well described by coupling a beam theory with the potential flow model of Lighthill. In particular, we show that the propagative nature of the elastic wave producing the propulsive force is strongly dependent on the dissipation of energy along the body of the swimmer.  相似文献   
40.
Cryogenic molecular beam experiments show that the ferroelectric dipole moments of small niobium clusters with an even number of valence electrons n are typically greater than those with odd n. This is verified in alloy clusters Nb N X M where X=Al, Au, O, Mn, Fe, and Co; N≤100;M≤3. Like in superconducting alloys, Mn doping quenches the effect while Al and Au enhance it, suggesting a relation between cluster ferroelectricity and bulk superconductivity. A correlated ground state is proposed where the even-odd effect is caused by the depolarizing effect of a single unpaired electron.  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