全文获取类型
收费全文 | 16887篇 |
免费 | 1750篇 |
国内免费 | 958篇 |
专业分类
电工技术 | 847篇 |
综合类 | 2123篇 |
化学工业 | 2215篇 |
金属工艺 | 1641篇 |
机械仪表 | 1310篇 |
建筑科学 | 2031篇 |
矿业工程 | 455篇 |
能源动力 | 302篇 |
轻工业 | 571篇 |
水利工程 | 439篇 |
石油天然气 | 306篇 |
武器工业 | 141篇 |
无线电 | 1236篇 |
一般工业技术 | 2866篇 |
冶金工业 | 533篇 |
原子能技术 | 121篇 |
自动化技术 | 2458篇 |
出版年
2024年 | 54篇 |
2023年 | 193篇 |
2022年 | 295篇 |
2021年 | 422篇 |
2020年 | 503篇 |
2019年 | 467篇 |
2018年 | 465篇 |
2017年 | 562篇 |
2016年 | 662篇 |
2015年 | 592篇 |
2014年 | 895篇 |
2013年 | 1004篇 |
2012年 | 1113篇 |
2011年 | 1152篇 |
2010年 | 858篇 |
2009年 | 944篇 |
2008年 | 923篇 |
2007年 | 1091篇 |
2006年 | 1029篇 |
2005年 | 838篇 |
2004年 | 762篇 |
2003年 | 762篇 |
2002年 | 641篇 |
2001年 | 543篇 |
2000年 | 517篇 |
1999年 | 391篇 |
1998年 | 313篇 |
1997年 | 289篇 |
1996年 | 237篇 |
1995年 | 179篇 |
1994年 | 163篇 |
1993年 | 136篇 |
1992年 | 111篇 |
1991年 | 82篇 |
1990年 | 73篇 |
1989年 | 63篇 |
1988年 | 52篇 |
1987年 | 30篇 |
1986年 | 26篇 |
1985年 | 20篇 |
1984年 | 22篇 |
1983年 | 15篇 |
1982年 | 14篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1966年 | 5篇 |
1964年 | 13篇 |
1963年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
防腐蚀施工工艺掌握的好坏,直接影响到工程投入生产后的使用寿命,为保证工程质量,以太钢不锈冷轧改造工程冷线防腐为例,对其常发生的质量通病进行认真分析,总结出一套行之有效的施工技术。 相似文献
32.
The technique of analytical pyrolysis has been used to characterize 40 similar mid-rank western Kentucky coals of widely differing ASTM Gieseler plasticity. Certain pyrolysis/g.c. variables were shown to correlate well with both ASTM Gieseler and isothermal plasticity. Highly plastic coals were shown to exhibit certain characteristic peaks in the 450 °C pyrogram which were absent in the pyrogram of the non-plastic coals. Two coals, representing the two extremes in plasticity, were selected for further study. After extraction with solvents such as DMF the characteristic peaks were absent in the 450 °C pyrogram of the extraction residue of the highly plastic coal. These peaks were also shown to decrease with increasing severity of air oxidation of the plastic coal. This technique appears to be a useful tool for the analysis of mid-rank plastic coals and supports the view that the substances contained in the bitumen fraction of these coals are involved in the development of the plastic state. 相似文献
33.
等径弯角挤压工艺(ECAEP)研究现状 总被引:3,自引:0,他引:3
等径弯角挤压是制备块状细晶材料的一种大塑性变形工艺,目前得到国内外高度重视.本文简要介绍了等径弯角挤压工艺的基本原理和变形特点,从理论上对其变形方式和机理进行了分析,并详细介绍了该工艺的应用领域。 相似文献
34.
本文研究了具有典型分解特征的Al-Zn-Ce非晶合金的形成和晶化过程,探讨了各种相的生成顺序。XRD和DSC测试结果表明强烈的化合物短程序有利于Al-Zn-Ce非晶合金的形成。在Al-Zn-Ce非晶合金的晶化过程中存在复杂的相选择行为,多种相的竞争形核和有限生长使其具有复杂的结构特点。同时,结果也表明冷速对该体系非晶的形成有很大影响。 相似文献
35.
Delevoye-Turrell Yvonne; Giersch Anne; Wing Alan M.; Danion Jean-Marie 《Canadian Metallurgical Quarterly》2007,116(1):56
Many everyday activities depend on the capacity to organize and smoothly execute motor sequences. The authors tested the hypothesis that a sequencing deficit is associated with schizophrenia. They used a new method to distinguish between lower and higher order mechanisms for the impairment. The 1st task involved triggered sequences in which sensory information from 1 movement was the cue for initiation of the following movement. Results showed that the motor sequences were performed as fluently in patients as in controls. The 2nd and 3rd tasks involved sequences in which the entire movement sequence could be preplanned. Patients executed the sequences less fluently than controls but only under the condition where action sequences were required. Furthermore, the patients' fluency deficit increased with sequence complexity. The high discrimination power of Task 3 gave the authors a means to control for a potential psychometric confound involving differential discriminating power and to argue in favor of a specific higher order motor fluency deficit in patients with schizophrenia. It is suggested that basic lower order mechanisms that integrate sensory information with outgoing motor commands are preserved in schizophrenia, whereas higher order integrative mechanisms that are required for the smooth coordination of motor sequences are impaired. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
36.
已往库存论中的决策模型,它是把现实过程用数学的方法进行分析,得到决策值,但不能看到决策的过程,不能反映出现实生活中的不确定性、动态性。运用Delphi 7.0和SQL server 2000对销售过程进行了动态仿真,利用Newsboy模型的推广(S,s)订购策略来监控库存并做出决策,这样就体现出此过程的不确定性、动态性;且举出了一个仿真商品销售的实例,对其中的一些关键技术,如何仿真、算法的实现等进行了阐述。 相似文献
37.
In this report, we describe the nature of intermediate order in silicon as determined by recent measurements on thin films using transmission electron microscopy (TEM) and Raman scattering. The TEM images show in addition to the expected continuous random network (CRN), the presence of highly ordered quasi-one-dimensional “chain-like objects” (CLO's) that are 1–2 nm wide and tens of nm long that meander and show some evidence of cross-linking with each other. The presence of these objects correlate to a Raman feature centered at 490 cm−1 whose width is 35–40 cm−1, and is used to quantify the heterogeneity in terms of the CLO and CRN (=475 cm−1 scattering) concentrations. The 490 and 35 cm−1 values are consistent with bond angle deviations approaching 0°, and thus reinforces an association with the CLOs. We find that in reference quality a-Si:H (made using pure SiH4), the CLO concentration is about 5 vol%, while in state-of-the-art material using high H2 levels of dilution during processing, it increases to about 15%. Increased stability of such material to light-soaking is thus not mediated by a direct volumetric replacement of poor with high-quality components. Rather, an important characteristic of intermediate order in silicon is the low-dimensional aspect of its order, which allows it to influence more total volume than which it is itself composed. Consistent with these and other recent findings, we propose a tensegrity model of amorphous silicon. 相似文献
38.
大塑性变形制备纳米结构金属 总被引:5,自引:0,他引:5
细化晶粒是改善材料性能的有效手段,传统的压力加工技术(如轧制、挤压、拉拔和锻造等)可以细化晶粒(微米量级)。纳米结构金属由于具有很小的晶粒尺寸(20-500nm)和独特的缺陷结构,从而表现出优异的物理—力学性能。大塑性变形(SPD)具有将铸态粗晶金属的晶粒细化到纳米量级的巨大潜力,近年来已引起人们的极大关注。介绍了4种大塑性变形制备纳米结构金属的方法、原理、变形特点及应用,分析了纳米结构金属的强度和超塑性变形特征,以及当前研究中存在的主要问题,并对大塑性变形技术的应用前景进行了展望。 相似文献
39.
40.
橡塑共混热塑性弹性体的形态结构与性能 总被引:2,自引:0,他引:2
综述了影响共混热塑性弹性体的形态结构与性能的主要因素。 相似文献