全文获取类型
收费全文 | 118971篇 |
免费 | 9905篇 |
国内免费 | 5683篇 |
专业分类
电工技术 | 7363篇 |
技术理论 | 11篇 |
综合类 | 8144篇 |
化学工业 | 19158篇 |
金属工艺 | 7223篇 |
机械仪表 | 7170篇 |
建筑科学 | 9734篇 |
矿业工程 | 3662篇 |
能源动力 | 3656篇 |
轻工业 | 7060篇 |
水利工程 | 2100篇 |
石油天然气 | 7550篇 |
武器工业 | 940篇 |
无线电 | 13458篇 |
一般工业技术 | 14178篇 |
冶金工业 | 5811篇 |
原子能技术 | 1461篇 |
自动化技术 | 15880篇 |
出版年
2024年 | 543篇 |
2023年 | 1999篇 |
2022年 | 3370篇 |
2021年 | 4855篇 |
2020年 | 3541篇 |
2019年 | 3070篇 |
2018年 | 3449篇 |
2017年 | 3863篇 |
2016年 | 3435篇 |
2015年 | 4554篇 |
2014年 | 5679篇 |
2013年 | 6811篇 |
2012年 | 7248篇 |
2011年 | 7848篇 |
2010年 | 7165篇 |
2009年 | 6534篇 |
2008年 | 6624篇 |
2007年 | 6427篇 |
2006年 | 6442篇 |
2005年 | 5502篇 |
2004年 | 3967篇 |
2003年 | 3894篇 |
2002年 | 4304篇 |
2001年 | 3710篇 |
2000年 | 3035篇 |
1999年 | 3209篇 |
1998年 | 2362篇 |
1997年 | 2048篇 |
1996年 | 2072篇 |
1995年 | 1640篇 |
1994年 | 1282篇 |
1993年 | 948篇 |
1992年 | 787篇 |
1991年 | 590篇 |
1990年 | 417篇 |
1989年 | 342篇 |
1988年 | 305篇 |
1987年 | 186篇 |
1986年 | 133篇 |
1985年 | 92篇 |
1984年 | 71篇 |
1983年 | 50篇 |
1982年 | 56篇 |
1981年 | 32篇 |
1980年 | 40篇 |
1979年 | 12篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1959年 | 2篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Infiltration and localization of preferential infiltration zones at the dam abutment are measured using radioactive tracer tests of flow in boreholes,meanwhile interconnection between boreholes and the energing water points is analysed.The theory and practice of radioactive tracer synthetic detective method are described to give methods and calculation formulae used under the condition of stable flow in single well to measure permeability coefficient and hydrostatic heads.Major single hole techniques including measurement for seepage line,velocity,rate of seepage flow and relationship of recharge of groundwater in aquifers are introduced briefly.The possibilities offered by natureal tracers are analysed,uincluding electric-conduct,pH-value and temperature of water as well as stable isotopes(D,^18O) and tritium.Furthermore,the sensibilities of this theory and methods were confirmed by detecting seepage flow field of Xinanjiang Dam. 相似文献
52.
In group assessment, the focus is on finding high‐authority experts to improve the reliability of assessment results. In this study, we propose an authority updating algorithm while considering the power and judgement reliability of an expert on the basis of social networks and post‐evaluations. A network power index is established and used to reflect the power of an expert while considering social networks. The measurement of the judgement reliability of an expert considers the post‐evaluation of the objects selected by experts, thereby more scientifically reflecting the reliability of experts. The analysis shows the following: although the social‐network structure influences the authority of experts, the influence weakens when the assessment group is a highly or even fully connected group; the network effect may increase the authority of some experts and reduce that of others, and it will weaken as the network connectivity increases; moreover, the judgement reliability and authority of an expert while considering post‐evaluation can encourage him/her to make fair assessments and strive to reduce his/her motivation and cognitive biases. 相似文献
53.
Machine Learning - Research showed that deep learning models are vulnerable to membership inference attacks, which aim to determine if an example is in the training set of the model. We propose a... 相似文献
54.
Yang Chao Ding Yijie Meng Qiaozhen Tang Jijun Guo Fei 《Neural computing & applications》2021,33(17):11387-11399
Neural Computing and Applications - RNA-binding proteins play an important role in the biological process. However, the traditional experiment technology to predict RNA-binding residues is... 相似文献
55.
多媒体技术是以数字技术为基础的综合技术。本文结合文科学生的特点,探讨了《多媒体技术与应用》课程设置与教学。 相似文献
56.
Catalysis Letters - Pd-based heterogeneous nanocatalysts have wide application in chemical industry. However, the traditional synthesis process contains multi-steps such as impregnation, dry,... 相似文献
57.
Silicon - In this paper, an analytical model for negative capacitance double gate field effect transistor (NC-DG-FET) is proposed. This model includes interface traps and temperature effects, which... 相似文献
59.
铸铁在700℃时氧化过程的观察 总被引:4,自引:0,他引:4
利用光学显微镜、电子探针以及扫描电镜研究了灰铁、球铁和蠕铁在700℃时的氧化过程。结果表明:(1)灰铁的氧化主要沿石墨与基体的相界面进行,初生奥氏体枝晶对氧的侵入具有一定的阻碍作用;(2)球铁是沿晶界比先氧化来实现其间接氧化的;(3)蠕铁氧化的模式主要取决于蠕化率的高低。 相似文献
60.
Electron Emission from Barium Strontium Titanate Ceramics 总被引:1,自引:0,他引:1
Shutao Chen Xianlin Dong Shuxin Zheng Ziqiu Zhu Chuanxiang Tang 《Journal of the American Ceramic Society》2006,89(7):2118-2122
This paper focuses on understanding the influence of materials' properties on the ferroelectric electron emission. Ferroelectric ( x =1.0 and 0.8) and paraelectric ( x =0.67 and 0.5) compositions of barium strontium titanate (Ba x Sr(1− x ) TiO3 ) system were chosen for study based on their different ferroelectric and dielectric properties. Similar emission current waveforms were obtained from four compositions with negative triggering voltage applied to the rear electrode of the samples. It was difficult to explain the experimental results using the spontaneous polarization-switching model. The mechanism of electron emission from Ba x Sr(1− x ) TiO3 ceramics was ascertained to surface plasma emission. 相似文献