全文获取类型
收费全文 | 25432篇 |
免费 | 1798篇 |
国内免费 | 1149篇 |
专业分类
电工技术 | 1438篇 |
技术理论 | 1篇 |
综合类 | 2076篇 |
化学工业 | 2412篇 |
金属工艺 | 1263篇 |
机械仪表 | 1366篇 |
建筑科学 | 3075篇 |
矿业工程 | 1035篇 |
能源动力 | 725篇 |
轻工业 | 1461篇 |
水利工程 | 884篇 |
石油天然气 | 1537篇 |
武器工业 | 612篇 |
无线电 | 4178篇 |
一般工业技术 | 2091篇 |
冶金工业 | 1165篇 |
原子能技术 | 333篇 |
自动化技术 | 2727篇 |
出版年
2024年 | 22篇 |
2023年 | 156篇 |
2022年 | 223篇 |
2021年 | 289篇 |
2020年 | 298篇 |
2019年 | 297篇 |
2018年 | 306篇 |
2017年 | 450篇 |
2016年 | 536篇 |
2015年 | 554篇 |
2014年 | 1040篇 |
2013年 | 1039篇 |
2012年 | 1532篇 |
2011年 | 1694篇 |
2010年 | 1387篇 |
2009年 | 1461篇 |
2008年 | 1763篇 |
2007年 | 2284篇 |
2006年 | 2083篇 |
2005年 | 1836篇 |
2004年 | 1601篇 |
2003年 | 1368篇 |
2002年 | 1060篇 |
2001年 | 972篇 |
2000年 | 802篇 |
1999年 | 623篇 |
1998年 | 496篇 |
1997年 | 402篇 |
1996年 | 355篇 |
1995年 | 298篇 |
1994年 | 240篇 |
1993年 | 189篇 |
1992年 | 155篇 |
1991年 | 118篇 |
1990年 | 101篇 |
1989年 | 82篇 |
1988年 | 68篇 |
1987年 | 35篇 |
1986年 | 43篇 |
1985年 | 20篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 12篇 |
1979年 | 4篇 |
1966年 | 6篇 |
1964年 | 4篇 |
1957年 | 7篇 |
1955年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
61.
化工软测量技术研究进展 总被引:2,自引:0,他引:2
详细说明了软测量技术的含义以及软测量系统的组成。在此基础上,介绍了软测量技术中基于机理分析建模、应用状态观测器建模、应用统计分析建模、神经元网络、模糊技术、以及支持向量机的智能建模等软测量建模理论方法和最新研究成果,之后介绍了小波分析、推断控制算法在软测量数据处理中的应用,最后介绍了基于虚拟仪器开发平台的软测量系统实现技术。 相似文献
62.
A new method of studying the corrosion inhibition mechanism of rare earth metal(REM) on LC4 Al alloy with the spilt cell technique was studied. The principle and experimental method of the spilt cell technique were analyzed. By measuring the change of net-electric current between the two electrodes caused by the change of the amount of oxygen in the solution and the addition of CeCl3, the influence of corrosive performance of CeCl3 on LC4 super-power aluminum alloy in the 0.1 mol·L−1 NaCl solution was investigated. Meanwhile, the conditional changes of pH values, CeCl3 solution, additire and time of performance were also studied. Finally, the features of electrode surface were revealed by using SEM and X-ray energy-dispersive spectrometry (EDS). By combining these with other electric chemical techniques, such as potential-time curve, polarization curve et al. 相似文献
63.
64.
Generalized difference control of parallel streams temperatures 总被引:1,自引:0,他引:1
A furnace with multiple parallel passes and multiple burners is commonly seen in petroleum refineries. In order to maintain the furnace running in a safe, stable, and high-efficiency state it is necessary to control the outlet temperatures of the multiple passes to be the same. Due to the fact that the process of the oil heating in such furnace is nonlinear, multivariable, time varying, has serious coupling among passes, has frequent dynamic changes and a large time delay, traditional control methods have trouble in controlling these temperatures, and some advanced control methods, including predictive control, adaptive control, and robust control, are usually too complex for convenient use. In this paper, a control technique, called differences control technique (DsCT), is proposed to distribute the stream flowrates such that the stream temperatures are as identical as possible. The principle of the proposed technique is explained and demonstrated, and the results of its application to a real-life petroleum refinery furnace are also reported. The DsCT technique has the following advantages: it does not need complicated design procedures, the controller structure is simple, it is easy to apply, and it can be canonically applied to furnaces with different number of passes. 相似文献
65.
This paper presents the mass transfer results from an impinging liquid jet to a rotating disk. The mass transfer coefficients were measured using the electrochemical limiting diffusion current technique (ELDCT). Rotational Reynolds number (Rer) in the range of 3.4 × 104–1.2 × 105, jet Reynolds number (Rej) 1.7 × 104–5.3 × 104 and non-dimensional jet-to-disk spacing (H/d) 2–8 were taken into consideration as parameters. It was found that the jet impingement resulted in a substantial enhancement in the mass transfer compared to the case of the rotating disk without jet. 相似文献
66.
67.
Experiments were carried out to investigate the characteristics of oil-gas flow in a horizontal pipe on a large scale (with the inner diameter D = 125 mm). With the experimental data, the flow patterns were presented. Through the analyses for the flow regime transition, it was found that there was a critical superficial velocity of liquid phase for the flow regime transiting from stratified flow to slug flow. The slug flow could not occur until the superficial velocity of liquid phase was higher than the critical velocity. For the flow pattern transiting from stratified to slug flow, the transmitting velocity of gas phase decreases with the augmentation of superficial velocity of liquid phase. On the basis of the experiments, numerical simulations of different flow patterns and their transitions were performed with the use of the Volume Of Fluid (VOF) technique. The results of the computations are shown to match well with the measured data in the experiments. 相似文献
68.
青藏铁路西格二线混凝土冻融试验研究 总被引:1,自引:0,他引:1
由于工期的要求,青藏铁路西格增建二线必须进行冬期施工。根据工程状况,分析了混凝土受冻的破坏机理,针对施工环境及对混凝土设计强度和要求,进行了大量冻融试验分析,对引气剂、水胶比、砂率、粉煤灰掺量等原材料与混凝土含气量的关系及其混凝土搅拌温度与静停时间等对混凝土性能的影响进行了分析与技术论证,确保了该线冬期混凝土施工顺利进行。 相似文献
69.
70.