全文获取类型
收费全文 | 152873篇 |
免费 | 14836篇 |
国内免费 | 7970篇 |
专业分类
电工技术 | 10167篇 |
技术理论 | 9篇 |
综合类 | 11252篇 |
化学工业 | 24368篇 |
金属工艺 | 9323篇 |
机械仪表 | 10589篇 |
建筑科学 | 12509篇 |
矿业工程 | 5133篇 |
能源动力 | 4565篇 |
轻工业 | 11844篇 |
水利工程 | 3006篇 |
石油天然气 | 9548篇 |
武器工业 | 1489篇 |
无线电 | 17136篇 |
一般工业技术 | 16557篇 |
冶金工业 | 6633篇 |
原子能技术 | 1532篇 |
自动化技术 | 20019篇 |
出版年
2024年 | 733篇 |
2023年 | 2911篇 |
2022年 | 5499篇 |
2021年 | 7586篇 |
2020年 | 5525篇 |
2019年 | 4391篇 |
2018年 | 4764篇 |
2017年 | 5186篇 |
2016年 | 4707篇 |
2015年 | 6800篇 |
2014年 | 8141篇 |
2013年 | 9292篇 |
2012年 | 10663篇 |
2011年 | 11184篇 |
2010年 | 9618篇 |
2009年 | 9260篇 |
2008年 | 8911篇 |
2007年 | 8327篇 |
2006年 | 8221篇 |
2005年 | 7008篇 |
2004年 | 4711篇 |
2003年 | 4418篇 |
2002年 | 4435篇 |
2001年 | 3866篇 |
2000年 | 3263篇 |
1999年 | 3253篇 |
1998年 | 2415篇 |
1997年 | 2028篇 |
1996年 | 1927篇 |
1995年 | 1601篇 |
1994年 | 1310篇 |
1993年 | 857篇 |
1992年 | 734篇 |
1991年 | 505篇 |
1990年 | 399篇 |
1989年 | 326篇 |
1988年 | 252篇 |
1987年 | 165篇 |
1986年 | 134篇 |
1985年 | 78篇 |
1984年 | 50篇 |
1983年 | 45篇 |
1982年 | 58篇 |
1981年 | 35篇 |
1980年 | 44篇 |
1979年 | 25篇 |
1978年 | 2篇 |
1965年 | 1篇 |
1959年 | 4篇 |
1951年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
32.
目的:鉴定中国白酒发酵过程中的微生物种类,研究关键酶的特征与作用机制有利于提高白酒的优质品率。方法:本研究用形态学和生理学、16S rRNA、gyr B基因和antiSMASH分析的方法对酒曲中的一株微生物进行了验证;对该菌株的特性进行了研究,采用分子建模的方法获得了羧酸酯酶的3D模型,用分子对接的方法探讨了该菌株的羧酸酯酶的机理。结果:该菌株为产羧酸酯酶的革兰氏阴性菌Pb1(MW580690);该菌株呈现典型的S型生长曲线,产物曲线为S型,羧酸酯酶活化最优pH范围为5.0~9.0。分子对接结果显示Phe21A为该酶具有催化活性的主要氨基酸,水解三丁酸甘油酯为丁酸和甘油。分子对接结果显示三丁酸甘油酯经过构象变化被转移到催化中心后,进一步被加工;酶的亲水性和疏水性的相互作用表面有利于配体向下转移,进而从疏水性通道释放产物到的酶表面。结论:产羧酸酯酶的菌株为贝莱斯芽胞杆菌,并为羧酸酯酶水解三丁酸甘油酯类物质的底物识别、转移和催化机理提供了新的见解。 相似文献
33.
34.
35.
With the emergence of large-scale knowledge base, how to use triple information to generate natural questions is a key technology in question answering systems. The traditional way of generating questions require a lot of manual intervention and produce lots of noise. To solve these problems, we propose a joint model based on semi-automated model and End-to-End neural network to automatically generate questions. The semi-automated model can generate question templates and real questions combining the knowledge base and center graph. The End-to-End neural network directly sends the knowledge base and real questions to BiLSTM network. Meanwhile, the attention mechanism is utilized in the decoding layer, which makes the triples and generated questions more relevant. Finally, the experimental results on SimpleQuestions demonstrate the effectiveness of the proposed approach. 相似文献
36.
Anaerobic co-digestion of food waste and FOG with sewage sludge – realising its potential in Ireland
Olumide Wesley Awe Yaqian Zhao Ange Nzihou Doan Pham Minh Nathalie Lyczko 《The International journal of environmental studies》2018,75(3):496-517
The severe environmental pollution in many countries is caused by indiscriminate discharge of large quantities of food waste (FW), fat oil and grease (FOG) and sewage sludge (SS) to the environment. There are many possible treatment routes, but anaerobic digestion (AD) is now well accepted for treating several kinds of organic wastes. But AD of FW alone presents some operational challenges because of substrates and variability. Anaerobic co-digestion of two or more substrates is better than single substrate digestion. This can use a plant’s unused capacity, in line with the trend to renewable energy. Co-digestion technology, although well established in many European countries, is still in its infancy in Ireland. There are problems with different regulatory arrangements. They should be resolved. The paper reviews anaerobic co-digestion technology is reviewed, with special focus on possible application in Ireland. 相似文献
37.
Zhongkai Zhao Yohanes A. Situmorang Ping An Nichaboon Chaihad Jing Wang Xiaogang Hao Guangwen Xu Abuliti Abudula Guoqing Guan 《化学工程与技术》2020,43(4):625-640
In the future, hydrogen will be an important energy carrier and industrial raw material. Catalytic steam reforming of bio-oils is a promising and economically viable technology for hydrogen production. However, during the reforming process, the catalysts are rapidly deactivated due to coke formation and sintering. Thus, maintaining the activity and stability of catalysts is the key issue in this process. Optimized operation conditions could extend the catalyst lifetime by affecting the coke morphology or promoting coke gasification. This article summarizes the recent developments in the field of catalytic steam reforming of bio-oils, focusing on the operation conditions, the properties of the catalysts, and the effects of the catalyst supports. The expected insights into the catalytic steam reforming of bio-oils will provide further guidance for hydrogen production from bio-oils. 相似文献
38.
39.
40.