全文获取类型
收费全文 | 14157篇 |
免费 | 1102篇 |
国内免费 | 567篇 |
专业分类
电工技术 | 765篇 |
综合类 | 744篇 |
化学工业 | 2449篇 |
金属工艺 | 735篇 |
机械仪表 | 889篇 |
建筑科学 | 944篇 |
矿业工程 | 387篇 |
能源动力 | 434篇 |
轻工业 | 795篇 |
水利工程 | 199篇 |
石油天然气 | 975篇 |
武器工业 | 77篇 |
无线电 | 1967篇 |
一般工业技术 | 1811篇 |
冶金工业 | 701篇 |
原子能技术 | 109篇 |
自动化技术 | 1845篇 |
出版年
2024年 | 48篇 |
2023年 | 258篇 |
2022年 | 408篇 |
2021年 | 580篇 |
2020年 | 390篇 |
2019年 | 337篇 |
2018年 | 383篇 |
2017年 | 436篇 |
2016年 | 404篇 |
2015年 | 534篇 |
2014年 | 718篇 |
2013年 | 843篇 |
2012年 | 823篇 |
2011年 | 985篇 |
2010年 | 827篇 |
2009年 | 763篇 |
2008年 | 807篇 |
2007年 | 744篇 |
2006年 | 786篇 |
2005年 | 698篇 |
2004年 | 449篇 |
2003年 | 390篇 |
2002年 | 318篇 |
2001年 | 305篇 |
2000年 | 296篇 |
1999年 | 427篇 |
1998年 | 371篇 |
1997年 | 290篇 |
1996年 | 278篇 |
1995年 | 192篇 |
1994年 | 189篇 |
1993年 | 124篇 |
1992年 | 104篇 |
1991年 | 69篇 |
1990年 | 61篇 |
1989年 | 38篇 |
1988年 | 30篇 |
1987年 | 11篇 |
1986年 | 25篇 |
1985年 | 6篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 16篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
用医药工业的副产物乙酰基次黄嘌呤(Ⅰ)在弱酸条件下水解,生成次黄嘌呤(Ⅱ),经三氟氧磷在吡啶溶液中缩合,生成6-吡啶盐中间体(Ⅲ),再与苄胺反应,制得高效植物细胞分裂素6-BA(Ⅳ)。 相似文献
22.
We present an approach for animating cracks and fractures in cartoon style. In our method we take a 2D hand-drawn object as input and then construct a 2.5D model of the object in order to approximate the object volume. Next, we generate the Voronoi textures on the 2.5D object model for visual abstraction of cartoon cracks. Further, cracking gaps on the Voronoi textures are widened progressively until Voronoi cells split apart and finally fall onto ground according to simplified physical rules. With minimum user intervention, our model is able to generate cartoon cracks and fractures animations procedurally, as demonstrated by examples given in the paper. 相似文献
23.
Using immune genetic algorithm based hybrid techniques for short-term unit commitment problem 总被引:2,自引:0,他引:2
G.-C. Liao 《Electrical Engineering (Archiv fur Elektrotechnik)》2005,87(5):267-279
This paper presents a hybrid chaos search (CS), immune algorithm (IA)/genetic algorithm (GA), and fuzzy system (FS) method (CIGAFS) for solving short-term thermal generating unit commitment (UC) problems. The UC problem involves determining the start-up and shut-down schedules for generating units to meet the forecasted demand at the minimum cost. The commitment schedule must satisfy other constraints such as the generating limits per unit, reserve, and individual units. First, we combined the IA and GA, then we added the CS and the FS approach. This hybrid system was then used to solve the UC problems. Numerical simulations were carried out using three cases: 10, 20, and 30 thermal unit power systems over a 24 h period. The produced schedule was compared with several other methods, such as dynamic programming (DP), Lagrangian relaxation (LR), standard genetic algorithm (SGA), traditional simulated annealing (TSA), and traditional Tabu search (TTS). A comparison with an immune genetic algorithm (IGA) combined with the CS and FS was carried out. The results show that the CS and FS all make substantial contributions to the IGA. The result demonstrated the accuracy of the proposed CIGAFS approach. 相似文献
24.
This paper presents a new route about producing carbon black,by wich the natural gas cracking is carried out in the absence of oxygen thanks to an electric energy supply externally given by a plasma jet.The carbon black produced by this process has a narrow size distribution and a small average diameter of 38nm as well as a highly branched aggregate.The higher DBP value of 1.40ml/g shows it should be a high structure carbon black.The FTIR spectra shows that there are lots of aromatic c-c bonds and a large amount of nitrogen-coutaining functional groups on the carbon blacks surface,such as-NH,-CN as we3ll as -CH,-OH,-COOH groups. 相似文献
25.
本文主要介绍了广钢汽拖AV40-11轴流压缩机组的结构和特点,控制系统概要、应用效果。 相似文献
26.
Jintuo Zhu Xinjian He Liang Wang Xiaoxue Liao Guangping Teng Pengli Jing 《矿业科学技术学报(英文版)》2022,32(1):215-224
High humidity and high dust concentration in deep coal mines may severely challenge the performance of respirators worn by coal miners.This paper aims at quantitatively evaluating the respirators used in deep coal mines and providing scientific guidance for the respiratory protection of miners.Based on the self-designed in-situ PM2.5collector,controllable PM2.5generator,human breathing simulator,and respirator simulation testing system,under the simulated deep mine working ... 相似文献
27.
膨胀土地区开挖渠道滑坡的规律与特征 总被引:3,自引:0,他引:3
在安徽省近百处开挖渠道滑坡分析的基础上,结合工程地质条件,对膨胀土地区开挖渠道滑坡在滑动面的形态及其形成、滑坡过程和滑坡分布等方面的规律和特征进行了研究。 相似文献
28.
Two thermomechanical coupled elastic-plastic finite element (FE) models were developed for predicting the 12-pass continuous rolling process of GCrl 5 rod and wire steel. The distances between stands in the proposed models were set according to the actual values, and the billets were shortened in the models to reduce the calculation time. To keep the continuity of simulation, a technique was developed to transfer temperature data between the meshes of different models in terms of nodal parameters by interpolation functions. The different process variables related to the rolling process, such as temperature, total equivalent plastic strain, equivalent plastic strain rate, and contact friction force, were analyzed. Also, the proposed models were applied to analyze the reason for the occurrence of an excessive spread in width. Meanwhile, it was also utilized to assess the influence of the roll diameter change on the simulated results such as temperature and rolling force. The simulated results of temperature are found to agree well with the measured results. 相似文献
29.
本文论述了西门子6RA70装置在双边剪夹送辊传动系统中的应用,解决了夹送辊不同步而出现的钢板走偏问题。 相似文献
30.
结合调研测试的实际工程,根据实际工程中地埋管地源热泵系统中水系统的形式及特点,归纳了设计、运行管理、设备故障等几个方面的水系统常见的问题。探讨了地埋管地源热泵水系统的设计问题,指出某些工程水系统存在的问题及解决思路;分析水系统故障的原因及表现,通过对水系统运行状态的观察与测试,从机组COP及系统能效比的角度分析水系统故障的影响:对于运行管理方面,提出相应的水系统形式的运行建议,为优化地埋管地源热泵的设计及运行管理提供了相应参考。 相似文献