全文获取类型
收费全文 | 157061篇 |
免费 | 14128篇 |
国内免费 | 7467篇 |
专业分类
电工技术 | 9548篇 |
技术理论 | 8篇 |
综合类 | 10610篇 |
化学工业 | 25403篇 |
金属工艺 | 9654篇 |
机械仪表 | 11000篇 |
建筑科学 | 12985篇 |
矿业工程 | 5220篇 |
能源动力 | 4456篇 |
轻工业 | 10334篇 |
水利工程 | 3020篇 |
石油天然气 | 10250篇 |
武器工业 | 1416篇 |
无线电 | 17947篇 |
一般工业技术 | 17783篇 |
冶金工业 | 7435篇 |
原子能技术 | 1695篇 |
自动化技术 | 19892篇 |
出版年
2024年 | 719篇 |
2023年 | 2812篇 |
2022年 | 5179篇 |
2021年 | 6955篇 |
2020年 | 5390篇 |
2019年 | 4306篇 |
2018年 | 4596篇 |
2017年 | 5351篇 |
2016年 | 4850篇 |
2015年 | 6784篇 |
2014年 | 8196篇 |
2013年 | 9746篇 |
2012年 | 10494篇 |
2011年 | 11419篇 |
2010年 | 9895篇 |
2009年 | 9505篇 |
2008年 | 9307篇 |
2007年 | 8564篇 |
2006年 | 8574篇 |
2005年 | 7280篇 |
2004年 | 4611篇 |
2003年 | 4145篇 |
2002年 | 3877篇 |
2001年 | 3533篇 |
2000年 | 3269篇 |
1999年 | 3585篇 |
1998年 | 2845篇 |
1997年 | 2359篇 |
1996年 | 2301篇 |
1995年 | 1950篇 |
1994年 | 1583篇 |
1993年 | 1082篇 |
1992年 | 881篇 |
1991年 | 647篇 |
1990年 | 493篇 |
1989年 | 414篇 |
1988年 | 321篇 |
1987年 | 207篇 |
1986年 | 169篇 |
1985年 | 102篇 |
1984年 | 75篇 |
1983年 | 67篇 |
1982年 | 61篇 |
1981年 | 44篇 |
1980年 | 44篇 |
1979年 | 28篇 |
1976年 | 4篇 |
1967年 | 3篇 |
1959年 | 5篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Lü Qing Xu Bin Yu Yang Zhan Wei Zhao Yu Zheng Jun Ji Jian 《Bulletin of Engineering Geology and the Environment》2021,80(8):6513-6525
Bulletin of Engineering Geology and the Environment - Many uncertainties exist in pile-stabilized slopes which make their design substantially complicated. In this paper, a first-order reliability... 相似文献
32.
33.
Kazuo Tsubota Stephen C. Pflugfelder Zuguo Liu Christophe Baudouin Hyo Myung Kim Elisabeth M. Messmer Friedrich Kruse Lingyi Liang Jimena Tatiana Carreno-Galeano Maurizio Rolando Norihiko Yokoi Shigeru Kinoshita Reza Dana 《International journal of molecular sciences》2020,21(23)
Over the past decades, the number of patients with dry eye disease (DED) has increased dramatically. The incidence of DED is higher in Asia than in Europe and North America, suggesting the involvement of cultural or racial factors in DED etiology. Although many definitions of DED have been used, discrepancies exist between the various definitions of dry eye disease (DED) used across the globe. This article presents a clinical consensus on the definition of DED, as formulated in four meetings with global DED experts. The proposed new definition is as follows: “Dry eye is a multifactorial disease characterized by a persistently unstable and/or deficient tear film (TF) causing discomfort and/or visual impairment, accompanied by variable degrees of ocular surface epitheliopathy, inflammation and neurosensory abnormalities.” The key criteria for the diagnosis of DED are unstable TF, inflammation, ocular discomfort and visual impairment. This definition also recommends the assessment of ocular surface epitheliopathy and neurosensory abnormalities in each patient with suspected DED. It is easily applicable in clinical practice and should help practitioners diagnose DED consistently. This consensus definition of DED should also help to guide research and clinical trials that, to date, have been hampered by the lack of an established surrogate endpoint. 相似文献
34.
35.
To realize joint optimization of spatial diversity and equalization combining in the intersymbol interference (ISI) channel, an iterative equalization combining algorithm is proposed. The proposed algorithm uses the coefficients of Turbo equalization to calculate the combination weights without estimating the signal to noise ratio in each diversity branch. The equalized symbols from different diversity branches are combined, and the extrinsic information output from the decoder is fed back to the equalizers, so as to exchange soft information between the equalizers and the decoder. The performance of the proposed algorithm is analyzed using the extrinsic information transfer (EXIT) chart and verified by simulations. Results show that our approach fully exploits time domain information from the multipath channel and spatial domain information from multi receiving antennas, which efficiently improve the performance of the receiver in the severe ISI channel. 相似文献
36.
37.
Anxiang Su Gaoxing Ma Minhao Xie Yang Ji Xiangfei Li Liyan Zhao Qiuhui Hu 《International Journal of Food Science & Technology》2019,54(6):2277-2287
In this study, in vitro digestion and fermentation of Flammulina velutipes -derived polysaccharides (FVP) were investigated. It was found that FVP mainly consisted of 48.45% glucose, 15.40% mannose, 14.60% xylose, 11.80% fucose and 9.90% galactose. The -human saliva, simulated gastric and small intestinal juices conditions did not break down the FVP. Based on in vitro fermentation tests, FVP modulated the composition of gut microbiota by elevating the amounts of Bifidobacteriaceae and Bacteroidaceae and reducing the numbers of genera Lachnospiraceae and Enterococcaceae. Meanwhile, FVP affected the synthesis of short-chain fatty acids derived from gut microbiota. 相似文献
38.
39.
Spinel LiSr0·1Cr0·1Mn1·8O4 was synthesised by high temperature solid state method in order to enhance the electrochemical performance. The LiSr0·1Cr0·1Mn1·8O4 (LSCMO) materials were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical tests. The XRD and SEM studies confirm that LSCMO had spinel crystal structure with a space group of Fd3m, and the particle of LSCMO shows irregular shape. The cyclic voltammetry data illustrated that the heavy current charge–discharge performance of LMO was improved by Sr2+ and Cr3+ doping. The galvanostatic charge–discharge of LSCMO cathode materials was measured at 1, 5, 10 and 20 C. The results indicated that LSCMO improved the capacity retention. 相似文献