全文获取类型
收费全文 | 48419篇 |
免费 | 6127篇 |
国内免费 | 3443篇 |
专业分类
电工技术 | 4770篇 |
技术理论 | 1篇 |
综合类 | 3790篇 |
化学工业 | 7053篇 |
金属工艺 | 2803篇 |
机械仪表 | 3143篇 |
建筑科学 | 3909篇 |
矿业工程 | 1681篇 |
能源动力 | 1429篇 |
轻工业 | 3655篇 |
水利工程 | 1298篇 |
石油天然气 | 2339篇 |
武器工业 | 644篇 |
无线电 | 6149篇 |
一般工业技术 | 5418篇 |
冶金工业 | 1806篇 |
原子能技术 | 467篇 |
自动化技术 | 7634篇 |
出版年
2024年 | 392篇 |
2023年 | 1328篇 |
2022年 | 2564篇 |
2021年 | 3511篇 |
2020年 | 2433篇 |
2019年 | 1818篇 |
2018年 | 1848篇 |
2017年 | 2020篇 |
2016年 | 1804篇 |
2015年 | 2439篇 |
2014年 | 2909篇 |
2013年 | 3292篇 |
2012年 | 3763篇 |
2011年 | 3841篇 |
2010年 | 3310篇 |
2009年 | 3108篇 |
2008年 | 3008篇 |
2007年 | 2709篇 |
2006年 | 2401篇 |
2005年 | 2127篇 |
2004年 | 1330篇 |
2003年 | 1007篇 |
2002年 | 915篇 |
2001年 | 782篇 |
2000年 | 699篇 |
1999年 | 599篇 |
1998年 | 391篇 |
1997年 | 334篇 |
1996年 | 303篇 |
1995年 | 239篇 |
1994年 | 203篇 |
1993年 | 121篇 |
1992年 | 101篇 |
1991年 | 77篇 |
1990年 | 55篇 |
1989年 | 41篇 |
1988年 | 33篇 |
1987年 | 24篇 |
1986年 | 32篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 2篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1959年 | 7篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
实施油气回收的必要性和技术方案的探讨 总被引:8,自引:0,他引:8
郝保良 《石油化工管理干部学院学报》2002,(2):41-42,69
简要介绍油气回收技术;从环保和增加经济效益的角度,以福建炼化公司的实际情况为例提出了油气回收的方案,并对实行该方案的必要性和经济效益做了分析;希望增强炼化企业对油气回收问题的重视,达到安全生产、改善环境和节约能源的目的。 相似文献
12.
13.
14.
Y. L. Hao R. Yang M. Niinomi D. Kuroda Y. L. Zhou K. Fukunaga A. Suzuki 《Metallurgical and Materials Transactions A》2003,34(4):1007-1012
Alloys for implant devices require improved strength but a reduced Young’s modulus, in order to become mechanically more compatible
with adjacent bone tissues. In this study, a new metastable β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (wt pct), was subjected to aging treatment to produce different microstructures,
and the resulting mechanical properties, including the Young’s modulus, were measured. The Young’s modulus of this alloy is
found to be sensitive to microstructures generated by various heat treatments. For microstructures varying from (α + β) to (α + β + ω) and (β + ω), the Young’s modulus increases with an accompanying increase in tensile strength and hardness, but decreases in ductility.
The (β + ω) microstructure has a low strength, high modulus, and poor ductility and cannot be used for biomedical applications. For
an (α + β) microstructure, the volume fraction of the phases is shown to be the main factor that determines the mechanical properties. 相似文献
15.
Yanqing Ji Hao Ying John Yen Shizhuo Zhu Daniel C. Barth‐Jones Richard E. Miller R. Michael Massanari 《国际智能系统杂志》2007,22(8):827-845
Discovering unknown adverse drug reactions (ADRs) in postmarketing surveillance as early as possible is highly desirable. Nevertheless, current postmarketing surveillance methods largely rely on spontaneous reports that suffer from serious underreporting, latency, and inconsistent reporting. Thus these methods are not ideal for rapidly identifying rare ADRs. The multiagent systems paradigm is an emerging and effective approach to tackling distributed problems, especially when data sources and knowledge are geographically located in different places and coordination and collaboration are necessary for decision making. In this article, we propose an active, multiagent framework for early detection of ADRs by utilizing electronic patient data distributed across many different sources and locations. In this framework, intelligent agents assist a team of experts based on the well‐known human decision‐making model called Recognition‐Primed Decision (RPD). We generalize the RPD model to a fuzzy RPD model and utilize fuzzy logic technology to not only represent, interpret, and compute imprecise and subjective cues that are commonly encountered in the ADR problem but also to retrieve prior experiences by evaluating the extent of matching between the current situation and a past experience. We describe our preliminary multiagent system design and illustrate its potential benefits for assisting expert teams in early detection of previously unknown ADRs. © 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 827–845, 2007. 相似文献
16.
Hao Chen 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2005,51(5):1854-1856
We prove a result which reduces the computation of the linear complexity of a sequence over GF(pm) (p is an odd prime) with period 2n (n is a positive integer such that there exists an element bisinGF(pm), bn=-1) to the computation of the linear complexities of two sequences with period n. By combining with some known algorithms such as the Berlekamp-Massey algorithm and the Games-Chan algorithm we can determine the linear complexity of any sequence over GF(pm) with period 2tn (such that 2 t|pm-1 and gcd(n,pm-1)=1) more efficiently 相似文献
17.
18.
Multimode parameter extraction for multiconductor transmissionlines via single-pass FDTD and signal-processing techniques 总被引:1,自引:0,他引:1
Yuanxun Wang Hao Ling 《Microwave Theory and Techniques》1998,46(1):89-96
We present two approaches to extract the broadband multimode parameters of guided wave structures from a single-pass finite-difference time-domain (FDTD) simulation. They include a two-dimensional (2-D) Fourier transform (FT) algorithm and a super-resolution estimation of signal parameters via rotational invariance technique (ESPRIT) algorithm. Comparison is made to show the superiority of the super-resolution approach. As a typical application, a three-line coupled microstrip structure is studied. After a single-pass FDTD simulation, broadband multimode parameters such as propagation constants, modal-field templates, and modal impedances are extracted and verified against published data obtained by the spectral-domain method. The main feature of this parameter-extraction methodology is that it decouples the computational electromagnetics engine (in this case, the FDTD simulator) from the post-processing parameter-extraction algorithm, thus providing more flexibility and connectivity among the various simulation tools 相似文献
19.
提出了溅射-气体-聚集共沉积制备金属/金属(介质)复合团簇镶嵌薄膜的新方法,并利用该方法成功地在方华膜衬底上制备了系列Fe/Ag及CaF2复合团簇镶嵌薄膜样品。透射电镜分析结果表明,样品中Fe(Cu)团簇都较好地镶嵌于Ag(CaF2)基质中,其结构为两种材料的多晶共存形态。进一步分析发现,与块材相比,Fe/Ag样品中Fe团簇晶格常数呈现出不同程度的收缩,而Cu/CaF2样品中Cu团簇晶格常数则呈现出不同程度的膨胀。运用附加压力的模型对该现象进行了解释。 相似文献
20.