全文获取类型
收费全文 | 606767篇 |
免费 | 21049篇 |
国内免费 | 9069篇 |
专业分类
电工技术 | 19054篇 |
技术理论 | 14篇 |
综合类 | 11505篇 |
化学工业 | 93429篇 |
金属工艺 | 25800篇 |
机械仪表 | 23740篇 |
建筑科学 | 25755篇 |
矿业工程 | 6461篇 |
能源动力 | 16553篇 |
轻工业 | 45121篇 |
水利工程 | 6818篇 |
石油天然气 | 16743篇 |
武器工业 | 1367篇 |
无线电 | 78365篇 |
一般工业技术 | 104838篇 |
冶金工业 | 92085篇 |
原子能技术 | 9868篇 |
自动化技术 | 59369篇 |
出版年
2023年 | 4062篇 |
2022年 | 7824篇 |
2021年 | 10983篇 |
2020年 | 8091篇 |
2019年 | 7908篇 |
2018年 | 10336篇 |
2017年 | 11156篇 |
2016年 | 10807篇 |
2015年 | 10692篇 |
2014年 | 15469篇 |
2013年 | 30034篇 |
2012年 | 21807篇 |
2011年 | 27098篇 |
2010年 | 22281篇 |
2009年 | 23714篇 |
2008年 | 23879篇 |
2007年 | 23358篇 |
2006年 | 22303篇 |
2005年 | 20073篇 |
2004年 | 16736篇 |
2003年 | 16125篇 |
2002年 | 14903篇 |
2001年 | 15057篇 |
2000年 | 14475篇 |
1999年 | 15896篇 |
1998年 | 32226篇 |
1997年 | 22945篇 |
1996年 | 18377篇 |
1995年 | 14112篇 |
1994年 | 12272篇 |
1993年 | 11636篇 |
1992年 | 8359篇 |
1991年 | 7780篇 |
1990年 | 7359篇 |
1989年 | 6896篇 |
1988年 | 6452篇 |
1987年 | 5293篇 |
1986年 | 5179篇 |
1985年 | 5650篇 |
1984年 | 5092篇 |
1983年 | 4769篇 |
1982年 | 4378篇 |
1981年 | 4390篇 |
1980年 | 4086篇 |
1979年 | 3788篇 |
1978年 | 3554篇 |
1977年 | 4320篇 |
1976年 | 5856篇 |
1975年 | 3004篇 |
1974年 | 2932篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Feng Wenran Li Zhen Chen Yingying Chen Jinyang Lang Haoze Wan Jianghong Gao Yan Dong Haitao 《Journal of Materials Science》2022,57(3):1881-1889
Journal of Materials Science - Although chalcogenide materials continue to generate considerable interest due to great potentials for various optoelectronic devices, annealing for a long time in... 相似文献
2.
Chen Wen-Kuo Chang Jing-Rong Chen Long-Sheng Hsu Rui-Yang 《Multimedia Tools and Applications》2022,81(6):8317-8347
Multimedia Tools and Applications - With the advancement of technology and the spread of the COVID19 epidemic, learning can no longer only be done through face-to-face teaching. Numerous digital... 相似文献
3.
Xiao Zhu Chen Yanxun Jiang Hongbo Hu Zhenzhen Lui John C. S. Min Geyong Dustdar Schahram 《Wireless Networks》2022,28(7):3305-3322
Wireless Networks - Unmanned aerial vehicles (UAV) have been widely used in various fields because of their high mobility and portability. At the same time, due to the rapid development of... 相似文献
4.
5.
6.
7.
Can Ercan S. Esra Safran Artuğ Türkmenoğlu Uğur Karabakal 《Journal of surfactants and detergents》2021,24(1):139-147
Garzan oil field is located at the south east of Turkey. It is a mature oil field and the reservoir is fractured carbonate reservoir. After producing about 1% original oil in place (OOIP) reservoir pressure started to decline. Waterflooding was started in order to support reservoir pressure and also to enhance oil production in 1960. Waterflooding improved the oil recovery but after years of flooding water breakthrough at the production wells was observed. This increased the water/oil ratio at the production wells. In order to enhance oil recovery again different techniques were investigated. Chemical enhanced oil recovery (EOR) methods are gaining attention all over the world for oil recovery. Surfactant injection is an effective way for interfacial tension (IFT) reduction and wettability reversal. In this study, 31 different types of chemicals were studied to specify the effects on oil production. This paper presents solubility of surfactants in brine, IFT and contact angle measurements, imbibition tests, and lastly core flooding experiments. Most of the chemicals were incompatible with Garzan formation water, which has high divalent ion concentration. In this case, the usage of 2-propanol as co-surfactant yielded successful results for stability of the selected chemical solutions. The results of the wettability test indicated that both tested cationic and anionic surfactants altered the wettability of the carbonate rock from oil-wet to intermediate-wet. The maximum oil recovery by imbibition test was reached when core was exposed 1-ethly ionic liquid after imbibition in formation water. Also, after core flooding test, it is concluded that considerable amount of oil can be recovered from Garzan reservoir by waterflooding alone if adverse effects of natural fractures could be eliminated. 相似文献
8.
Multimedia Tools and Applications - Mammograms are the images used by radiologists to diagnose breast cancer. Breast cancer is one of the most common cancers in women. The early detection of breast... 相似文献
9.
Shanshan Zhuang Wenxiong Zheng Yunong Na Naiyi Chen Fan Gong Bingxuan Huang Stephen Brennan Charles Congyi Liu Jian Cheng Lukai Ma Huifan Liu 《International Journal of Food Science & Technology》2022,57(2):1093-1103
The β-Carotene (BC), an important precursor of vitamin A (VA), possesses antioxidant activity but is fat-soluble and has low bioavailability. In previous in-vitro assays evaluating antioxidant and 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) free radical scavenging, both BC and VA showed a strong ability to scavenge radicals and protected cells from oxidative stress. Here, we used artificially simulated gastrointestinal digestion and Caco-2 cell absorption models to evaluate the bioavailability of the BC during gastrointestinal digestion and absorption using high-performance liquid chromatography (HPLC) analysis. We observed high absorptive and transfer rates of BC and detected retinol metabolites (Vitamin A). Therefore, BC can be detected in the acidic gastrointestinal environment using HPLC. Optimised method provided better separation of BC and VA in the column, improving the accuracy of the test results. 相似文献
10.
Vijay Singh Sharanagat Prabhat K. Nema Lochan Singh Ankur Kumar 《International Journal of Food Science & Technology》2022,57(3):1654-1665
The effect of microwave roasting parameters (300, 450 and 600 W; 5, 10 and 15 min) on acrylamide content in sorghum grain was determined using High Pressure Liquid Chromatography (HPLC)-photo diode array (PDA) detector coupled with C-18 column. Samples roasted at 300 and 450 W did not possess acrylamide, whereas 600 W (15 min) favoured formation of 2740.19 µg/kg of acrylamide, levels far exceeding the defined European Union (EU) limits. The chronic daily intake (CDI) for acrylamide through consumption of such grain flour was 3.25–9.5-fold higher to Joint FAO/WHO Expert Committee on Food Additives (JECFA) defined high exposure limits. The margin of exposure (MOE) values ranged from 4.3 to 12.76 and from 11.07 to 32.27 for neoplastic and neurological effects, respectively, demonstrating high exposure and serious health concerns associated with dietary intake of this toxicant. This study assesses the risk for the Indian population and highlights the importance of optimising process parameters for food product to minimise such exposure risks. 相似文献