全文获取类型
收费全文 | 8761篇 |
免费 | 940篇 |
国内免费 | 714篇 |
专业分类
电工技术 | 389篇 |
综合类 | 692篇 |
化学工业 | 1580篇 |
金属工艺 | 587篇 |
机械仪表 | 300篇 |
建筑科学 | 245篇 |
矿业工程 | 111篇 |
能源动力 | 253篇 |
轻工业 | 368篇 |
水利工程 | 84篇 |
石油天然气 | 177篇 |
武器工业 | 42篇 |
无线电 | 1194篇 |
一般工业技术 | 673篇 |
冶金工业 | 472篇 |
原子能技术 | 250篇 |
自动化技术 | 2998篇 |
出版年
2024年 | 7篇 |
2023年 | 98篇 |
2022年 | 112篇 |
2021年 | 228篇 |
2020年 | 198篇 |
2019年 | 157篇 |
2018年 | 151篇 |
2017年 | 199篇 |
2016年 | 231篇 |
2015年 | 247篇 |
2014年 | 423篇 |
2013年 | 467篇 |
2012年 | 613篇 |
2011年 | 731篇 |
2010年 | 734篇 |
2009年 | 896篇 |
2008年 | 784篇 |
2007年 | 829篇 |
2006年 | 729篇 |
2005年 | 429篇 |
2004年 | 347篇 |
2003年 | 289篇 |
2002年 | 317篇 |
2001年 | 211篇 |
2000年 | 199篇 |
1999年 | 159篇 |
1998年 | 93篇 |
1997年 | 86篇 |
1996年 | 60篇 |
1995年 | 60篇 |
1994年 | 39篇 |
1993年 | 45篇 |
1992年 | 33篇 |
1991年 | 31篇 |
1990年 | 29篇 |
1989年 | 22篇 |
1988年 | 15篇 |
1987年 | 14篇 |
1986年 | 4篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 12篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1975年 | 3篇 |
1974年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
21.
22.
CAS-BUS: A Test Access Mechanism and a Toolbox Environment for Core-Based System Chip Testing 总被引:2,自引:0,他引:2
As System on a Chip (SoC) testing faces new challenges, some new test architectures must be developed. This paper describes a Test Access Mechanism (TAM) named CAS-BUS that solves some of the new problems the test industry has to deal with. This TAM is scalable, flexible and dynamically reconfigurable. The CAS-BUS architecture is compatible with the IEEE P1500 standard proposal in its current state of development, and is controlled by Boundary Scan features.This basic CAS-BUS architecture has been extended with two independent variants. The first extension has been designed in order to manage SoC made up with both wrapped cores and non wrapped cores with Boundray Scan features. The second deals with a test pin expansion method in order to solve the I/O bandwidth problem. The proposed solution is based on a new compression/decompression mechanism which provides significant results in case of non correlated test patterns processing. This solution avoids TAM performance degradation.These test architectures are based on the CAS-BUS TAM and allow trade-offs to optimize both test time and area overhead. A tool-box environment is provided, in order to automatically generate the needed component to build the chosen SoC test architecture. 相似文献
23.
一般来说,新闻直播中镜头是固定的,不需要太多的操作。如今,使用可远程遥控的摄像设备已成为一个热点。本文主要以东方卫视为例,从选型、使用及日常维护等方面,对对AUTOCAM的进行简单介绍。 相似文献
24.
萃取分离锑铁是脆硫锑铅矿矿浆电解工艺过程的一个环节。P2 0 4可选择性地在NH4 Cl介质溶液中萃取铁。在 35 %(体积百分数 )P2 0 4、相比 (O/A) 1∶1、3级连续逆流萃取条件下 ,铁萃取率达 80 %~ 84%,锑、银基本不被萃取。含Fe总 1~ 1 4g/L的萃余液可返回矿浆电解循环使用。 相似文献
25.
Recent advances in isotropic conductive adhesives for electronics packaging applications 总被引:4,自引:0,他引:4
Isotropic conductive adhesives (ICAs) have recently received a lot of focus and attention from the researchers in electronics industry as a potential substitute to lead-bearing solders. Numerous studies have shown that ICAs possess many advantages over conventional soldering such as environmental friendliness, finer pitch printing, lower temperature processing and more flexible and simpler processing. However, complete replacement of soldering by ICAs is yet not possible owing to several limitations of ICAs which are mainly related to reliability aspects like limited impact resistance, unstable contact resistance, low adhesion and conductivity etc. Continued efforts for last 15 years have resulted in development of ICAs with improved properties. This review article is aimed at providing a better understanding of ICAs, their principles, performance and significant research and development work addressing the technological utility of ICAs. 相似文献
26.
Jatuporn Wittayakun Pongtanawat Khemthong Sanchai Prayoonpokarach 《Korean Journal of Chemical Engineering》2008,25(4):861-864
Rice husk silica (RHS) in amorphous phase with 98% purity was prepared from a waste rice husk from rice milling by leaching
with hydrochloric acid and calcination. The RHS was used effectively as a silica source for the synthesis of zeolite Y in
sodium form (NaY). The zeolite in pure phase was obtained from a two-step synthetic route in which the starting gels were
mixed, aged for 24 h at room temperature and crystallized for 24 h at 90 °C. The diameter of single crystal particles from
a scanning electron microscope was approximately 1.0 μm, whereas the average particle diameter from laser diffraction particle
size analyzer was approximately 10 μm because of the agglomeration of small crystals. Longer crystallization time in this
route resulted in a mixed phase containing NaY and zeolite P in sodium form (NaP). In addition, a one-step synthetic route
(no aging) was studied and the product was also a mixed phase zeolite. 相似文献
27.
28.
29.
30.
本文从应用出发,选择光学石英为衬底,采用热丝辅助射频化学气相沉积的方法沉积BPxN1—x薄膜,对样品进行了X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外—可见等测试。XRD、SEM结果显示薄膜多晶态,表面形貌随时间变化,最终为胞状;紫外—可见光光谱结果显示BPxN1—x薄膜的紫外吸收边随沉积时间的加长、PH3流量的增加而向长波长方向移动。因此,该材料的光学能隙可以通过生长工艺适当调整。另外,BPxN1—x薄膜与液晶层能较好匹配等特性更使其适用于紫外空间光调制器。 相似文献