全文获取类型
收费全文 | 144706篇 |
免费 | 15760篇 |
国内免费 | 10954篇 |
专业分类
电工技术 | 13000篇 |
技术理论 | 2篇 |
综合类 | 13865篇 |
化学工业 | 18496篇 |
金属工艺 | 9875篇 |
机械仪表 | 10055篇 |
建筑科学 | 11197篇 |
矿业工程 | 4957篇 |
能源动力 | 4435篇 |
轻工业 | 13591篇 |
水利工程 | 4730篇 |
石油天然气 | 5751篇 |
武器工业 | 2076篇 |
无线电 | 15930篇 |
一般工业技术 | 13794篇 |
冶金工业 | 5988篇 |
原子能技术 | 2398篇 |
自动化技术 | 21280篇 |
出版年
2024年 | 662篇 |
2023年 | 1973篇 |
2022年 | 4286篇 |
2021年 | 5970篇 |
2020年 | 4384篇 |
2019年 | 3298篇 |
2018年 | 3443篇 |
2017年 | 4156篇 |
2016年 | 4044篇 |
2015年 | 6065篇 |
2014年 | 7575篇 |
2013年 | 8962篇 |
2012年 | 11422篇 |
2011年 | 11933篇 |
2010年 | 11597篇 |
2009年 | 11142篇 |
2008年 | 11468篇 |
2007年 | 11181篇 |
2006年 | 9878篇 |
2005年 | 8261篇 |
2004年 | 6263篇 |
2003年 | 5083篇 |
2002年 | 5106篇 |
2001年 | 4586篇 |
2000年 | 3203篇 |
1999年 | 1686篇 |
1998年 | 767篇 |
1997年 | 656篇 |
1996年 | 514篇 |
1995年 | 409篇 |
1994年 | 315篇 |
1993年 | 256篇 |
1992年 | 171篇 |
1991年 | 139篇 |
1990年 | 104篇 |
1989年 | 87篇 |
1988年 | 66篇 |
1987年 | 59篇 |
1986年 | 48篇 |
1985年 | 21篇 |
1984年 | 22篇 |
1983年 | 27篇 |
1982年 | 18篇 |
1981年 | 18篇 |
1980年 | 25篇 |
1979年 | 17篇 |
1977年 | 3篇 |
1975年 | 4篇 |
1959年 | 15篇 |
1951年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Influence of electroplating conditions on magnetic properties of Fe-36wt.% Ni alloy film 总被引:1,自引:0,他引:1
A Fe-Ni soft magnetic film was prepared in sulphate solution by electroplating. The influences of the molar ratio of n [Fe2+ ]/ n [Ni2+ ], current density, bath temperature, pH and L-ascorbic acid concentration on magnetic properties of Fe-Ni alloy film were investigated. The results show that the saturated flux density(BS) of the film increases initially and decreases after it reaches the specific value with the increase of n [Fe2+ ]/ n [Ni2+ ] molar ratio, current density, bath temperature and pH. However, the relationship between L-ascorbic acid concentration and B S keeps linear. It is observed that the coercive force( Hc) is enhanced with the increase of n [Fe2+ ]/ n [Ni2+ ] molar ratio, current density and pH. By comparison, when the bath temperature increases, Hc always decreases. With the increase of L-ascorbic acid concentration, the coercive force increases initially and then decreases. 相似文献
102.
GAO Wenli SUI Zhitong North East University of Technology Shenyang China LU Ke LI Shuling WANG Jingtang State Key Laboratory for RSA Institute of Metal Research Academia Sinica Shenyang China Institute of Metal Research Academia Sinica Shenyang China 《金属学报(英文版)》1993,6(7):16-20
The crystallization kinetics of Pd-Cu-Si glass was studied by means of diferential scanningcalorimetry-Ⅱ.According to Kissinger peak shift meth(?)d and Arrhenius equation,theapparent activation energy was calculated.The crystallization kinetics follows Johnson-Mehl-Avrami equation with n=3.0 within 0.15相似文献
103.
板料弯曲回弹的有限元模拟影响因素研究 总被引:3,自引:1,他引:3
阐述了板料成形数值模拟中回弹问题的研究历史和发展现状,分析了塑性弯曲加工中工件发生弯曲回弹的原因、特点及有限元模拟过程的影响因素,总结了回弹模拟的算法,从成形过程模拟和回弹计算两方面系统分析了影响回弹模拟准确性和收敛性的主要因素及改进方向,讨论了模具设计中回弹的补偿算法 ,并提出了当前控制回弹的基本方法 相似文献
104.
The 5Cu40Zn55Al and 15Cu20Zn65Al alloys were prepared in the AI-Zn-Cu system, There exist the metastable phases ε and θ in the two alloys after homogenization treatment and furnace cooling, respectively. It is shown that the particles are refined from 3 mm to less than 10 μm after hammering the two alloys but there are still metastable phases. This means that the phase constituents of the two alloys have no changes by the deformation, which is different from that by balling. The phase constituents are not changed at room temperature by hammering, which is dependent on the deformation mechanism of hammering. 相似文献
105.
106.
Pythagorean fuzzy sets (PFSs), originally proposed by Yager (Yager, Abbasov. Int J Intell Syst 2013;28:436–452), are a new tool to deal with vagueness considering the membership grades are pairs satisfying the condition . As a generalized set, PFSs have close relationship with intuitionistic fuzzy sets (IFSs). PFSs can be reduced to IFSs satisfying the condition . However, the related operations of PFSs do not take different conditions into consideration. To better understand PFSs, we propose two operations: division and subtraction, and discuss their properties in detail. Then, based on Pythagorean fuzzy aggregation operators, their properties such as boundedness, idempotency, and monotonicity are investigated. Later, we develop a Pythagorean fuzzy superiority and inferiority ranking method to solve uncertainty multiple attribute group decision making problem. Finally, an illustrative example for evaluating the Internet stocks performance is given to verify the developed approach and to demonstrate its practicality and effectiveness. 相似文献
107.
108.
分组加工模式的应用是特色工艺研究和精细化加工的结合,目前被应用在了很多企业中。为了解决计划制订到生产调度指挥这一过程中的问题,企业采用了MES技术来优化这一模式下的工艺过程。分析了MES技术的应用。 相似文献
109.
110.
A noteworthy thing in desktop PCs is that they can provide a great opportunity to increase the performance of processing multimedia data by exploiting task- and data-parallelism with multi-core CPU and many-core GPU. This paper presents a high performance parallel implementation of 2D DCT on this heterogeneous computing environment. For this purpose, Intel TBB (threading building blocks) and OpenCL (Open Compute Language) are utilized for task- and data-parallelism, respectively. The simulation result shows that the parallel DCT implementations far the serial ones in processing speed. Especially, OpenCL implementation shows a linear speedup, a typical SIMD characteristic as the increase of 2D data sets. 相似文献