全文获取类型
收费全文 | 298645篇 |
免费 | 37747篇 |
国内免费 | 13925篇 |
专业分类
电工技术 | 19151篇 |
技术理论 | 17篇 |
综合类 | 21093篇 |
化学工业 | 56219篇 |
金属工艺 | 16591篇 |
机械仪表 | 18738篇 |
建筑科学 | 22484篇 |
矿业工程 | 8129篇 |
能源动力 | 8531篇 |
轻工业 | 27284篇 |
水利工程 | 5778篇 |
石油天然气 | 15318篇 |
武器工业 | 2772篇 |
无线电 | 35064篇 |
一般工业技术 | 38195篇 |
冶金工业 | 11942篇 |
原子能技术 | 2976篇 |
自动化技术 | 40035篇 |
出版年
2024年 | 957篇 |
2023年 | 3845篇 |
2022年 | 7643篇 |
2021年 | 11017篇 |
2020年 | 9372篇 |
2019年 | 9204篇 |
2018年 | 9810篇 |
2017年 | 11303篇 |
2016年 | 10988篇 |
2015年 | 14459篇 |
2014年 | 17294篇 |
2013年 | 20661篇 |
2012年 | 21348篇 |
2011年 | 22445篇 |
2010年 | 20766篇 |
2009年 | 19802篇 |
2008年 | 19105篇 |
2007年 | 18046篇 |
2006年 | 17359篇 |
2005年 | 14413篇 |
2004年 | 10506篇 |
2003年 | 9571篇 |
2002年 | 9521篇 |
2001年 | 8343篇 |
2000年 | 6879篇 |
1999年 | 5844篇 |
1998年 | 3898篇 |
1997年 | 3206篇 |
1996年 | 2964篇 |
1995年 | 2346篇 |
1994年 | 1923篇 |
1993年 | 1271篇 |
1992年 | 1070篇 |
1991年 | 769篇 |
1990年 | 586篇 |
1989年 | 490篇 |
1988年 | 343篇 |
1987年 | 245篇 |
1986年 | 192篇 |
1985年 | 100篇 |
1984年 | 72篇 |
1983年 | 74篇 |
1982年 | 71篇 |
1981年 | 58篇 |
1980年 | 61篇 |
1979年 | 30篇 |
1978年 | 6篇 |
1965年 | 3篇 |
1959年 | 15篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
61.
62.
Chengxiao Zhao Zupeng Chen Run Shi Xiaofei Yang Tierui Zhang 《Advanced materials (Deerfield Beach, Fla.)》2020,32(28):1907296
With the ambition of solving the challenges of the shortage of fossil fuels and their associated environmental pollution, visible-light-driven splitting of water into hydrogen and oxygen using semiconductor photocatalysts has emerged as a promising technology to provide environmentally friendly energy vectors. Among the current library of developed photocatalysts, organic conjugated polymers present unique advantages of sufficient light-absorption efficiency, excellent stability, tunable electronic properties, and economic applicability. As a class of rising photocatalysts, organic conjugated polymers offer high flexibility in tuning the framework of the backbone and porosity to fulfill the requirements for photocatalytic applications. In the past decade, significant progress has been made in visible-light-driven water splitting employing organic conjugated polymers. The recent development of the structural design principles of organic conjugated polymers (including linear, crosslinked, and supramolecular self-assembled polymers) toward efficient photocatalytic hydrogen evolution, oxygen evolution, and overall water splitting is described, thus providing a comprehensive reference for the field. Finally, current challenges and perspectives are also discussed. 相似文献
63.
Qi Yang Qilong Wu Yang Liu Shuiping Luo Xiaotong Wu Xixia Zhao Haiyuan Zou Baihua Long Wen Chen Yujia Liao Lanxi Li Pei Kang Shen Lele Duan Zewei Quan 《Advanced materials (Deerfield Beach, Fla.)》2020,32(36):2002822
Engineering novel Sn-based bimetallic materials could provide intriguing catalytic properties to boost the electrochemical CO2 reduction. Herein, the first synthesis of homogeneous Sn1−xBix alloy nanoparticles (x up to 0.20) with native Bi-doped amorphous SnOx shells for efficient CO2 reduction is reported. The Bi-SnOx nanoshells boost the production of formate with high Faradaic efficiencies (>90%) over a wide potential window (−0.67 to −0.92 V vs RHE) with low overpotentials, outperforming current tin oxide catalysts. The state-of-the-art Bi-SnOx nanoshells derived from Sn0.80Bi0.20 alloy nanoparticles exhibit a great partial current density of 74.6 mA cm−2 and high Faradaic efficiency of 95.8%. The detailed electrocatalytic analyses and corresponding density functional theory calculations simultaneously reveal that the incorporation of Bi atoms into Sn species facilitates formate production by suppressing the formation of H2 and CO. 相似文献
64.
65.
66.
67.
Requirements Engineering - In software reuse, the reuse of UML class diagram produced in design phase has received more attention due to the important influence on the following developing process.... 相似文献
68.
69.
Molecular structure and granule morphology of native and heat‐moisture‐treated pinhão starch 下载免费PDF全文
Vania Z. Pinto Khalid Moomand Nathan L. Vanier Rosana Colussi Franciene A. Villanova Elessandra R. Zavareze Loong‐Tak Lim Alvaro R. G. Dias 《International Journal of Food Science & Technology》2015,50(2):282-289
Pinhão seed is an unconventional source of starch and the pines grow up in native forests of southern Latin America. In this study, pinhão starch was adjusted at 15, 20 and 25% moisture content and heated to 100, 110 and 120 °C for 1 h. A decrease in λ max (starch/iodine complex) was observed as a result of increase in temperature and moisture content of HMT. The ratio of crystalline to amorphous phase in pinhão starch was determined via Fourier transform infra red by taking 1045/1022 band ratio. A decrease in crystallinity occurred as a result of HMT. Polarised light microscopy indicated a loss of birefringence of starch granules under 120 °C at 25% moisture content. Granule size distribution was further confirmed via scanning electron microscopy which showed the HMT effects. These results increased the understanding on molecular and structural properties of HMT pinhão starch and broadened its food and nonfood industrial applications. 相似文献
70.
Effect of gums on viability and β‐galactosidase activity of Lactobacillus spp. in milk drink during refrigerated storage 下载免费PDF全文
Bernice D. Karlton‐Senaye Reza Tahergorabi Valerie L. Giddings Salam A. Ibrahim 《International Journal of Food Science & Technology》2015,50(1):32-40
The viability and β‐galactosidase activity of four Lactobacillus strains in milk drink containing gums during 28 days of refrigerated storage at 4 °C were assessed. The population of Lactobacillus rhamnosus GGB101 and Lactobacillus rhamnosus GGB103 were maintained, whereas the population of Lactobacillus reuteri DSM20016 and Lactobacillus reuteri SD2112 significantly decreased. The recommended level of 6 log CFU g?1 was exceeded for all tested trains throughout storage. The highest viable number of Lactobacillus rhamnosus GGB103 (8.76 ± 0.03 log CFU mL?1) was obtained in the product containing carrageenan–maltodextrin. The addition of guar–locust bean–carrageenan led to 20‐fold increase in the level of β‐galactosidase activity for L. rhamnosus GGB101 (1208 ± 2.12 Miller units mL?1) compared to the control (61 ± 2.83 Miller units mL?1). Our results suggested that gums could be added to milk to improve viability and enhance β‐galactosidase activity of Lactobacillus. 相似文献