全文获取类型
收费全文 | 61790篇 |
免费 | 6720篇 |
国内免费 | 4013篇 |
专业分类
电工技术 | 6046篇 |
技术理论 | 3篇 |
综合类 | 5625篇 |
化学工业 | 4478篇 |
金属工艺 | 2767篇 |
机械仪表 | 4453篇 |
建筑科学 | 12645篇 |
矿业工程 | 2379篇 |
能源动力 | 1933篇 |
轻工业 | 2885篇 |
水利工程 | 3323篇 |
石油天然气 | 4158篇 |
武器工业 | 1416篇 |
无线电 | 4999篇 |
一般工业技术 | 5152篇 |
冶金工业 | 2123篇 |
原子能技术 | 692篇 |
自动化技术 | 7446篇 |
出版年
2024年 | 213篇 |
2023年 | 734篇 |
2022年 | 1595篇 |
2021年 | 1918篇 |
2020年 | 2186篇 |
2019年 | 1708篇 |
2018年 | 1602篇 |
2017年 | 2156篇 |
2016年 | 2377篇 |
2015年 | 2570篇 |
2014年 | 4038篇 |
2013年 | 3694篇 |
2012年 | 4880篇 |
2011年 | 5106篇 |
2010年 | 3849篇 |
2009年 | 3805篇 |
2008年 | 3447篇 |
2007年 | 4120篇 |
2006年 | 3707篇 |
2005年 | 3212篇 |
2004年 | 2665篇 |
2003年 | 2191篇 |
2002年 | 1869篇 |
2001年 | 1633篇 |
2000年 | 1301篇 |
1999年 | 1056篇 |
1998年 | 873篇 |
1997年 | 667篇 |
1996年 | 673篇 |
1995年 | 551篇 |
1994年 | 414篇 |
1993年 | 303篇 |
1992年 | 266篇 |
1991年 | 157篇 |
1990年 | 159篇 |
1989年 | 115篇 |
1988年 | 76篇 |
1987年 | 49篇 |
1986年 | 43篇 |
1985年 | 25篇 |
1984年 | 25篇 |
1981年 | 22篇 |
1980年 | 64篇 |
1979年 | 48篇 |
1965年 | 26篇 |
1964年 | 35篇 |
1960年 | 23篇 |
1959年 | 33篇 |
1956年 | 29篇 |
1955年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
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
82.
83.
Ryba Nancy L.; Cooper Virginia G.; Zapf Patricia A. 《Canadian Metallurgical Quarterly》2003,34(5):499
What is the current standard of practice for evaluations of juvenile competence to stand trial (JCST)? The present study surveyed psychologists regarding the practices used when conducting JCST evaluations. Respondents rated the importance of 17 elements that might be included in a JCST evaluation report. Of these elements, 7 were considered essential by 70% or more of respondents, with 9 additional elements rated as either essential or recommended. A majority of respondents felt that the use of psychological and forensic instruments was important. A list of tests used is provided, and the implications for the development of standards and policy are discussed to provide practitioners with additional knowledge that will help to further the state of the discipline. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
84.
一种新的直扩超宽带系统快速同步方案 总被引:1,自引:0,他引:1
本文提出了一种新的基于能量窗的直扩超宽带系统码片同步方法,通过设计具有重复特性的码来提高能量窗的信噪比,从向可以较为准确地获得码片同步,并将窗口中的信息作为接收端本地信号与接收信号进行匹配接收,这样可以存未知接收信号相位的情况下有效地接收多径能量,提高接收信噪比。在完成码片同步之后再进一步进行PN码的相位同步,这里以线性搜索为例分析得到超宽带信号总的平均同步时间,并与现有的超宽带同步方案进行了比较,新方案将信号捕获分成两部分完成,大大降低了超宽带信号捕获时间。 相似文献
85.
86.
Yue Fang 《时间序列分析杂志》2005,26(4):527-541
Abstract. We analyze, by simulation, the finite‐sample properties of goodness‐of‐fit tests based on residual autocorrelation coefficients (simple and partial) obtained using different estimators frequently used in the analysis of autoregressive moving‐average time‐series models. The estimators considered are unconditional least squares, maximum likelihood and conditional least squares. The results suggest that although the tests based on these estimators are asymptotically equivalent for particular models and parameter values, their sampling properties for samples of the size commonly found in economic applications can differ substantially, because of differences in both finite‐sample estimation efficiencies and residual regeneration methods. 相似文献
87.
文章探讨了GB 12437-2000标准规定的产品检验项目中,中包浸水试验的科学性问题和对批产品进行抽样时的样本代表性问题以及使用多段爆速仪测试爆速时应注意的样本量问题. 相似文献
89.
A. A. Kherani B. J. Prabhu K. E. Avrachenkov E. Altman 《Telecommunication Systems》2005,30(4):321-350
We study an Adaptive Window Protocol (AWP) with general increase and decrease profiles in the presence of window dependent
random losses. We derive a steady-state Kolmogorov equation, and then obtain its solution in analytic form for particular
TCP versions proposed for high speed networks, such as Scalable TCP and HighSpeed TCP. We also relate window evolution under
an AWP to workload process in queueing systems; this observation gives us a way to compare various AWP protocols. 相似文献
90.