全文获取类型
收费全文 | 110364篇 |
免费 | 9893篇 |
国内免费 | 5249篇 |
专业分类
电工技术 | 7041篇 |
技术理论 | 12篇 |
综合类 | 7934篇 |
化学工业 | 17949篇 |
金属工艺 | 5955篇 |
机械仪表 | 6537篇 |
建筑科学 | 8705篇 |
矿业工程 | 3034篇 |
能源动力 | 3038篇 |
轻工业 | 8920篇 |
水利工程 | 2106篇 |
石油天然气 | 5820篇 |
武器工业 | 982篇 |
无线电 | 13251篇 |
一般工业技术 | 12766篇 |
冶金工业 | 5148篇 |
原子能技术 | 1455篇 |
自动化技术 | 14853篇 |
出版年
2024年 | 560篇 |
2023年 | 1964篇 |
2022年 | 3737篇 |
2021年 | 4977篇 |
2020年 | 3855篇 |
2019年 | 3078篇 |
2018年 | 3470篇 |
2017年 | 3650篇 |
2016年 | 3461篇 |
2015年 | 4490篇 |
2014年 | 5588篇 |
2013年 | 6375篇 |
2012年 | 7125篇 |
2011年 | 7638篇 |
2010年 | 6550篇 |
2009年 | 6272篇 |
2008年 | 6240篇 |
2007年 | 5811篇 |
2006年 | 5598篇 |
2005年 | 4838篇 |
2004年 | 3457篇 |
2003年 | 3115篇 |
2002年 | 3042篇 |
2001年 | 2722篇 |
2000年 | 2603篇 |
1999年 | 2767篇 |
1998年 | 2160篇 |
1997年 | 1842篇 |
1996年 | 1790篇 |
1995年 | 1426篇 |
1994年 | 1270篇 |
1993年 | 895篇 |
1992年 | 730篇 |
1991年 | 502篇 |
1990年 | 415篇 |
1989年 | 385篇 |
1988年 | 278篇 |
1987年 | 198篇 |
1986年 | 138篇 |
1985年 | 98篇 |
1984年 | 79篇 |
1983年 | 55篇 |
1982年 | 64篇 |
1981年 | 42篇 |
1980年 | 43篇 |
1979年 | 17篇 |
1977年 | 9篇 |
1976年 | 13篇 |
1974年 | 11篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Many approaches have been proposed to enhance software productivity and reliability. These approaches typically fall into three categories: the engineering approach, the formal approach and the knowledge-based approach. But the optimal gain in software productivity cannot be obtained if one relies on only one of these approaches. This paper describes the work in knowledge-based software engineering conducted by the authors for the past 10 years. The final goal of the research is to develop a paradigm for software engineering which integrates the three approaches mentioned above. A knowledge-based tool which can support the whole process of software development is provided in this paper. 相似文献
12.
13.
LaNiO3 was synthesized by sol-gel method in which lanthanum nitrate and nickel nitrate were used as start materials and citric acid was used as complex for gel formation.The precursor was dried and subsequently heated at elevated temperature to form the desired product.XRD analysis shows that pure LaNiO3 was synthesized.Electrical conductivity and electrochemical performance of the material were tested.The electrical conductivity decreases from 34.5that there are current peaks in the curve, which is the evidence of the electrochemical activity of LaNiO3. 相似文献
14.
The results of study of the effects of yttria stabilization (0–6 mol.%) on the room-temperature fracture behavior and toughening mechanisms in zirconia-reinforced MoSi2 are presented in this paper. Transformation toughening is shown to occur only in composites reinforced with zirconia particles stabilized with 2 mol.% yttria. However, the fracture toughness levels are comparable in the other composites with yttria levels between 0 and 6 mol.%. Toughening in the other composites is attributed to the combined effects of residual stress, microcrack shielding/anti-shielding and/or crack deflection. A rigorous micromechanics-based model is presented for the estimation of residual stress levels in brittle materials reinforced with phases that can transform during cooling or under stress. The model is applied successfully to the rationalization of the observed fracture and toughening phenomena. 相似文献
15.
This paper shows that the mechanical and thermal properties of EPR cable dielectrics are very stable with temperature. Commercially available EPR and TRXLPE cable dielectrics typically have about the same thermal conductivity, although the thermal conductivity of TRXLPE above the melting point of the crystallites drops below that of the EPR dielectrics. The mechanical properties of EPR cable dielectrics are much more stable with temperature than those of the TRXLPE, as EPR polymer is essentially amorphous so that EPR cable dielectrics do not suffer from the very large thermal expansion of TRXLPE as its crystallites melt. 相似文献
16.
17.
Jing Wang Walker D.M. Xiang Lu Majhi A. Kruseman B. Gronthoud G. Villagra L.E. van de Wiel P.J.A. Eichenberger S. 《Design & Test of Computers, IEEE》2007,24(3):226-234
Excessive power supply noise during test can cause overkill. This article discusses two models for supply noise in delay testing and their application to test compaction. The proposed noise models avoid complicated power network analysis, making them much faster than existing power noise analysis tools. can cause performance degradation and 相似文献
18.
With the aim to reduce disorder and improve efficiency, nodes in an ad hoc network run a self-organization scheme to cooperatively organize the network. Although metrics such as complexity or self-stability are commonly used for evaluation, to the best of our knowledge, none of them quantifies the efficiency to build and maintain an organization (order). We henceforth apply the notion of entropy to ad hoc type wireless networks facilitating a quantification of the internal organizational state generated by different self-organization schemes. Invoking node and link failure probabilities, we expose the dependency of the organizational state on the self-organization protocol of choice. 相似文献
19.
A jet-printed digital-lithographic method, in place of conventional photolithography, was used to fabricate 64 /spl times/ 64 pixel (300 /spl mu/m pitch) matrix addressing thin-film transistor (TFT) arrays. The average hydrogenated amorphous silicon TFT device within an array had a threshold voltage of /spl sim/3.5 V, carrier mobility of 0.7 cm/sup 2//V/spl middot/s, subthreshold slope of 0.76 V/decade, and an on/off ratio of 10/sup 8/. 相似文献
20.
4G mobile communications: toward open wireless architecture 总被引:2,自引:0,他引:2