全文获取类型
收费全文 | 60909篇 |
免费 | 6020篇 |
国内免费 | 4113篇 |
专业分类
电工技术 | 5100篇 |
技术理论 | 1篇 |
综合类 | 5129篇 |
化学工业 | 9078篇 |
金属工艺 | 3410篇 |
机械仪表 | 4207篇 |
建筑科学 | 4719篇 |
矿业工程 | 1733篇 |
能源动力 | 1894篇 |
轻工业 | 4094篇 |
水利工程 | 1332篇 |
石油天然气 | 2679篇 |
武器工业 | 858篇 |
无线电 | 7509篇 |
一般工业技术 | 6746篇 |
冶金工业 | 2285篇 |
原子能技术 | 851篇 |
自动化技术 | 9417篇 |
出版年
2024年 | 273篇 |
2023年 | 865篇 |
2022年 | 1580篇 |
2021年 | 2403篇 |
2020年 | 1876篇 |
2019年 | 1505篇 |
2018年 | 1674篇 |
2017年 | 1920篇 |
2016年 | 1713篇 |
2015年 | 2598篇 |
2014年 | 3189篇 |
2013年 | 3947篇 |
2012年 | 4223篇 |
2011年 | 4467篇 |
2010年 | 4340篇 |
2009年 | 4172篇 |
2008年 | 4031篇 |
2007年 | 3921篇 |
2006年 | 3704篇 |
2005年 | 3027篇 |
2004年 | 2305篇 |
2003年 | 2170篇 |
2002年 | 2304篇 |
2001年 | 2003篇 |
2000年 | 1482篇 |
1999年 | 1134篇 |
1998年 | 781篇 |
1997年 | 649篇 |
1996年 | 587篇 |
1995年 | 460篇 |
1994年 | 366篇 |
1993年 | 300篇 |
1992年 | 254篇 |
1991年 | 170篇 |
1990年 | 151篇 |
1989年 | 109篇 |
1988年 | 91篇 |
1987年 | 48篇 |
1986年 | 61篇 |
1985年 | 31篇 |
1984年 | 22篇 |
1983年 | 18篇 |
1982年 | 23篇 |
1981年 | 21篇 |
1980年 | 19篇 |
1979年 | 10篇 |
1976年 | 11篇 |
1973年 | 6篇 |
1959年 | 7篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
61.
重金属污染物动态吸附试验及数学模拟 总被引:3,自引:0,他引:3
本文采用泥沙动力学中Rouse等人用来研究泥沙浓度沿垂线分布的装置。对泥沙吸附重金属污染物进行了动态模拟。试验分有底泥和无底泥两种情况。研究中发现在Rouse装置的水力、泥沙条件下泥沙吸附重金属污染物达到平衡状态需要6小时以上,由极坐标下的重金属迁移转化数学模型方程,在本文具体试验条件下进行数值求解,计算结果和试验结果合良好,说明数学模型是正确合理的试验是可靠的。计算时依据室内静态试验结果,对动态 相似文献
62.
This study proposes a new interactive multicriteria method for determining the best levels of the decision variables needed to optimize a stochastic computer simulation with multiple response variables. The method, called the Pairwise Comparison Stochastic Cutting Plane (PCSCP) method, combines good features from interactive multiple objective mathematical programming and response surface methodology. The major characteristics of the PCSCP method are: (1) it interacts progressively with the decision-maker (DM) to obtain her preferences, (2) it uses experimental design to explore the decision space adequately while reducing the burden on the DM, and (3) it uses the preference information provided by the DM and the sampling error in the responses to reduce the decision space. The mechanics of the method are illustrated with a numerical example. Some computational studies evaluating the method are also reported. 相似文献
63.
Kow Ming Chang Yuan Hung Chung Gin Ming Lin 《Electron Device Letters, IEEE》2002,23(5):255-257
Studies the anomalous variations of the OFF-state leakage current (IOFF) in n-channel poly-Si thin-film transistors (TFTs) under static stress. The dominant mechanisms for the anomalous IOFF can be attributed to (1) IOFF increases due to channel hot electrons trapping at the gate oxide/channel interface and silicon grain boundaries and (2) IOFF decreases due to hot holes accumulated/trapped near the channel/bottom oxide interface near the source region. Under the stress of high drain bias, serious impact ionization effect will occur to generate hot electrons and hot holes near the drain region. Some of holes will be injected into the gate oxide due to the vertical field (~(V_Gstress V_Dstress)/T OX) near the drain and the others will be migrated from drain to source along the channel due to lateral electric field (~V_Dstress/LCH) 相似文献
64.
In process-control system design, the Computer Aided Design (CAD) techniques have evolved a new generation of design techniques. This also paves the way for implementing Computer Integrated Manufacturing Systems (CIMS). However, the key issue to accomplishing the objectives in CAD is the automation of conceptual design. This paper first introduces the fundamentals of conceptual design for process-control system design. Then, a strategy to solve the problems in conceptual design is proposed. The associated system configuration and software implementation platform for developing intelligent systems for process control system design are presented. Finally, an application case is studied. 相似文献
65.
The recrystallization behaviour of cold drawn MP159 alloy was investigated by optical and TEM examinations. It is found that the platelet ε phase in the MP alloy inhibits the recrystallization,and this effect makes the MP159 alloy with high recrystallization temperature of about 920℃.This inhibition mainly comes from the increasing of the interfacial energy, which results from the change of the coherent interfaces of (0001)hcp//(111)fcc into the incoherent interfaces when the recrystallizing grain fronts bypass the platelet ε martensite. The increasing of the interfacial energy also causes the dissolution of a few segments on the ε martensite platelets, which decreases the strength of the MP alloy 相似文献
66.
67.
Polyvinyl alcohol (PVA) films containing 10% w/w of a model drug, sulphathiazole, were cast from aqueous solutions and subjected to heat treatment at specific temperatures for known periods of time. Heat treatment at temperatures above the Tg of the PVA films slowed down the rate of drug release from the films. Increasing the temperature of heat treatment from 120°C to 160°C further decreased the rate of drug release. On the other hand, if the heat treatment were conducted at a temperature below the Tg e.g. at 80°C, there were insignificant differences between the release profile of sulphathiazole from heat-treated films and that from untreated films. The duration of heat treatment affected the rate of drug release to a smaller extent compared to the temperature of heat treatment. These results correlated with the heat induced changes in the morphology of, and in the extent of water uptake by the PVA films. 相似文献
68.
Monolithic Catalysts with Low Noble-Metal Content for Exhaust Purification of Small Gasoline Engines
A series of low noble-metal coment monolithic catalysts for exhaust purification of small gasoline engines was investigated, and it was found that the Pt/Rh-OSM/Al2O3 (where OSM was oxygen storage material) catalyst with Ce0.5Zr0.5-MnOx(3%MnOx) OSM held low light-off temperature for CO, HC, and NO; quite wide three-way window, and outstanding thermal stability. The catalyst could efficiently comrol exhaust emission of small gasoline engines. 相似文献
69.
70.