全文获取类型
收费全文 | 80098篇 |
免费 | 7292篇 |
国内免费 | 4643篇 |
专业分类
电工技术 | 4965篇 |
技术理论 | 1篇 |
综合类 | 7601篇 |
化学工业 | 12479篇 |
金属工艺 | 4580篇 |
机械仪表 | 5077篇 |
建筑科学 | 5586篇 |
矿业工程 | 1864篇 |
能源动力 | 2128篇 |
轻工业 | 7545篇 |
水利工程 | 1647篇 |
石油天然气 | 3138篇 |
武器工业 | 674篇 |
无线电 | 9512篇 |
一般工业技术 | 8578篇 |
冶金工业 | 3336篇 |
原子能技术 | 1074篇 |
自动化技术 | 12248篇 |
出版年
2024年 | 306篇 |
2023年 | 1035篇 |
2022年 | 2012篇 |
2021年 | 2750篇 |
2020年 | 2156篇 |
2019年 | 1866篇 |
2018年 | 1978篇 |
2017年 | 2241篇 |
2016年 | 2224篇 |
2015年 | 3058篇 |
2014年 | 4077篇 |
2013年 | 4765篇 |
2012年 | 5526篇 |
2011年 | 5813篇 |
2010年 | 5534篇 |
2009年 | 5400篇 |
2008年 | 5305篇 |
2007年 | 5083篇 |
2006年 | 4886篇 |
2005年 | 4073篇 |
2004年 | 3358篇 |
2003年 | 2974篇 |
2002年 | 3573篇 |
2001年 | 3102篇 |
2000年 | 2124篇 |
1999年 | 1513篇 |
1998年 | 984篇 |
1997年 | 820篇 |
1996年 | 747篇 |
1995年 | 642篇 |
1994年 | 472篇 |
1993年 | 347篇 |
1992年 | 277篇 |
1991年 | 214篇 |
1990年 | 176篇 |
1989年 | 117篇 |
1988年 | 111篇 |
1987年 | 79篇 |
1986年 | 33篇 |
1985年 | 54篇 |
1984年 | 42篇 |
1983年 | 34篇 |
1982年 | 21篇 |
1981年 | 19篇 |
1980年 | 21篇 |
1979年 | 14篇 |
1977年 | 12篇 |
1976年 | 15篇 |
1959年 | 8篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
71.
Huan Huang 《Information Sciences》2010,180(19):3806-3813
This paper shows that the Zadeh’s extensions of sendograph-metric-continuous fuzzy-valued functions are sendograph-metric-continuous fuzzy functions. 相似文献
72.
Sangmun Shin Nguyen Khoa Viet Truong Byung Rae Cho Sung Hoon Hong 《Computers & Industrial Engineering》2011
Robust design (RD) and tolerance design (TD) have received much attention from researchers and practitioners for more than two decades, and a number of methodologies for modeling and optimizing the RD and TD processes have been studied. However, there is ample room for improvement. Because most existing research considers RD and TD as separate research fields, the primary objective of this paper is to develop a sequential robust–tolerance design method to jointly determine the best factor settings and the closed-form solutions for the optimal specification limits. We then apply the proposed method to a destructive quality characteristic. Finally, a case study and sensitivity analyses are performed for verification purposes, and further studies are discussed. 相似文献
73.
74.
Voting systems are common tools in a variety of areas. This paper studies parameterized computational complexity of control of Plurality, Condorcet and Approval voting systems, respectively. The types of controls considered include adding or deleting candidates or voters, under constructive or destructive setting. We obtain the following results: (1) constructive control by adding candidates in Plurality voting is W[2]-hard with respect to the parameter “number of added candidates”, (2) destructive control by adding candidates in Plurality voting is W[2]-hard with respect to the parameter “number of added candidates”, (3) constructive control by adding voters in Condorcet voting is W[1]-hard with respect to the parameter “number of added voters”, (4) constructive control by deleting voters in Condorcet voting is W[1]-hard with respect to the parameter “number of deleted voters”, (5) constructive control by adding voters in Approval voting is W[1]-hard with respect to the parameter “number of added voters”, and (6) constructive control by deleting voters in Approval voting is W[2]-hard with respect to the parameter “number of deleted voters”. 相似文献
75.
76.
Huan Xie Xin Luo Xiong Xu Haiyan Pan Xiaohua Tong 《International journal of remote sensing》2016,37(8):1826-1844
The successful launch of the Landsat 8 satellite continues the Earth observation of the Landsat series, which has been taking place for nearly 40 years. With the increase in the band number and the improved spectral range compared with the previous Landsat imagery, it will be possible to expand the application of the new Landsat 8 imagery. The purpose of this study is to explore water extraction based on the new Landsat 8 Operational Land Imager (OLI) imagery. According to the specific inland water conditions (clear water, turbid water, and eutrophic water), a number of highly adaptable water indices are assessed for water extraction using Landsat OLI imagery. The results show that clear water is the easiest to extract among the different types of waterbodies, with the highest average accuracy of 97%. The highest-accuracy methods are the automated water extraction index for shadow pixels (AWEIsh), the normalized difference water index using bands 4 and 7 (NDWI47), and the normalized difference water index using bands 3 and 7 (NDWI37), with accuracies of 98.55%, 95.50%, and 96.61%, corresponding to clear water, turbid water, and eutrophic water, respectively. Through the analysis of the different methods for optimal band selection, the seventh band OLI7 (shortwave infrared 2, SWIR-2) of Landsat OLI shows the best performance in water identification. When applying the water indices to water extraction, Otsu’s algorithm has been used to automatically select the water threshold. Using extensive experiments with Otsu’s algorithm and a manual method, it was found that Otsu’s algorithm can replace manual selection and has the ability to select an accurate threshold for water extraction. 相似文献
77.
78.
Deng Juan Zhao Shu Wang Yan Wang Lei Wang Hong Sha Hong 《Multimedia Tools and Applications》2017,76(7):10097-10117
Multimedia Tools and Applications - Most of the existing image encryption algorithms based on compressive sensing are too complex to operate. An image compression-encryption scheme with simple... 相似文献
79.
Mei Kum Khaw Chin Hong Ooi Faisal Mohd-Yasin Anh V. Nguyen Geoffrey M. Evans Nam-Trung Nguyen 《Microfluidics and nanofluidics》2017,21(6):110
This paper reports the dynamic behaviour of a magnetically actuated floating liquid marble by analysing the oscillation of the marble. A liquid marble is a liquid droplet coated with hydrophobic powder. Magnetite particles inside the marble make it magnetic. The marble floats on a carrier liquid that contains aqueous glycerol of various concentrations. A permanent magnet located under the carrier liquid drives the floating marble with the initial velocity. Stopping the magnet abruptly causes the marble to oscillate around its final position for a few seconds. The oscillation was recorded and analysed using customised image processing and evaluation software. The damped harmonic motion model was then applied to the data and tested. Subsequently, critical parameters of the system such as the initial displacement, friction correction factor, the apparent frequency and the spring constant were determined and discussed. The simple experimental set-up and convenient theoretical approach allow us to characterise the marble motion under the influence of a magnet with good accuracy. 相似文献
80.
ABSTRACTMobile technology has facilitated an emerging form of consumption practices called collaborative consumption. In this study, we investigate one such manifestation whereby merchants send group discount coupons to nearby consumers and encourage them to invite surrounding people to enjoy the discount together. We are interested to know if timing (morning vs. afternoon) and message framing (active vs. passive mutual helping tone) would increase the chance of an individual deciding to invite strangers (and invite a higher proportion of strangers if they did) to participate in the collaborative consumption. Facilitating the participation among strangers can help elevate the reach and influence of collaborative consumption, allowing its potential to be better exploited. Our field experiment findings show that in general people are more likely to invite strangers (and also a higher proportion of strangers in all their invitations) in the morning than in the afternoon. In addition, a message framed to ask the focal individual to actively help others enjoy the deal (active tone) is more effective than a message framed passively, i.e., to let others help him/her (passive tone) in the morning. However, passive tone framing can induce individuals to invite a higher proportion of strangers in the afternoon if they did invite others. These findings have important implications to merchants and app providers on how to more fully tap into the potential of collaborative consumption via mobile technology. 相似文献