全文获取类型
收费全文 | 846228篇 |
免费 | 86853篇 |
国内免费 | 57015篇 |
专业分类
电工技术 | 66254篇 |
技术理论 | 45篇 |
综合类 | 81488篇 |
化学工业 | 117464篇 |
金属工艺 | 55807篇 |
机械仪表 | 58808篇 |
建筑科学 | 66038篇 |
矿业工程 | 33886篇 |
能源动力 | 22416篇 |
轻工业 | 76431篇 |
水利工程 | 24341篇 |
石油天然气 | 40237篇 |
武器工业 | 11305篇 |
无线电 | 89522篇 |
一般工业技术 | 77694篇 |
冶金工业 | 36924篇 |
原子能技术 | 11749篇 |
自动化技术 | 119687篇 |
出版年
2024年 | 2880篇 |
2023年 | 12762篇 |
2022年 | 27870篇 |
2021年 | 37937篇 |
2020年 | 27896篇 |
2019年 | 20434篇 |
2018年 | 22610篇 |
2017年 | 25627篇 |
2016年 | 23166篇 |
2015年 | 35588篇 |
2014年 | 45315篇 |
2013年 | 53485篇 |
2012年 | 64896篇 |
2011年 | 69197篇 |
2010年 | 64571篇 |
2009年 | 61207篇 |
2008年 | 62440篇 |
2007年 | 60603篇 |
2006年 | 54730篇 |
2005年 | 45813篇 |
2004年 | 32173篇 |
2003年 | 23674篇 |
2002年 | 21912篇 |
2001年 | 19805篇 |
2000年 | 17471篇 |
1999年 | 12404篇 |
1998年 | 7923篇 |
1997年 | 6686篇 |
1996年 | 6241篇 |
1995年 | 5165篇 |
1994年 | 4113篇 |
1993年 | 2920篇 |
1992年 | 2341篇 |
1991年 | 1720篇 |
1990年 | 1404篇 |
1989年 | 1207篇 |
1988年 | 945篇 |
1987年 | 573篇 |
1986年 | 479篇 |
1985年 | 284篇 |
1984年 | 251篇 |
1983年 | 196篇 |
1982年 | 171篇 |
1981年 | 159篇 |
1980年 | 253篇 |
1979年 | 150篇 |
1977年 | 26篇 |
1976年 | 33篇 |
1959年 | 110篇 |
1951年 | 115篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
81.
利用双轴搅拌机的工作原理设计的石粉和脱硫石膏混合装置,将石粉和脱硫石膏混合成干湿均匀料加入水泥磨,既利用了石粉、节约了石子,又解决了水泥生产过程中脱硫石膏水分大、不便输送和难稳定入磨的问题,效果显著。 相似文献
82.
Xiaozhen Li Chao Yin Si Si Liew Chun-Sing Lee Kanyi Pu 《Advanced functional materials》2021,31(46):2106154
Optical imaging has played a pivotal role in deciphering in vivo bioinformatics but is limited by shallow penetration depth and poor imaging performance owing to interfering tissue autofluorescence induced by concurrent photoexcitation. The emergence of near-infrared (NIR) self-luminescence imaging independent of real-time irradiation has timely addressed these problems. There are two main kinds of self-luminescent agents, namely inorganic and organic luminophores. Inorganic luminophores usually suffer from long-term biotoxicity concerns resulting from potential heavy-metal ions leakage and nonbiodegradability, which hinders their further translational application. In contrast, organic luminophores, especially organic semiconducting luminophores (OSLs) with good biodegradable potential, tunable design, and outstanding optical properties, are preferred in biological applications. This review summarizes the recent progress of OSLs used in NIR afterglow, chemiluminescence, and bioluminescence imaging. Molecular manipulation and nanoengineering approaches of OSLs are discussed, with emphasis on strategies that can extend the emission wavelength from visible to NIR range and amplify luminescence signals. This review concludes with a discussion of current challenges and possible solutions of OSLs in the self-luminescence field. 相似文献
83.
84.
食品安全示范城市创建是食品安全治理体系的重要载体。本文系统性回顾食品安全治理体系相关研究,从“党政同责”、政府监管、市场主体、社会共治等四个治理主体,构建生产规范、产业转型升级等27个评价指标的治理标准,利用层次分析法实证分析了浙江省食品安全示范城市创建情况。结果表明:采用暗查暗访、现场检查、体系评估、示范引领答辩等形式,按照一定的评价流程、评价标准的食品安全示范城市创建,是实现食品安全现代化目标的重要载体。食品安全治理体系包括“治理载体—治理主体—治理标准—治理目标”。食品安全治理成效与跟踪评价、群众满意度以及体系评估高度关联。 相似文献
85.
Xuejie Li Yaqing Wen Jian Zhang Dongyun Ma Jie Zhang Yanxia An Xiaoyan Song Xiujuan Ren Weifeng Zhang 《International Journal of Food Science & Technology》2022,57(3):1544-1553
The effects of non-thermal plasma (NTP) on the physicochemical properties of wheat flour and the quality of fresh wet noodles ( FWN) were investigated. The results showed that NTP effectively decreased the total plate count (TPC), yeast and mould count (YMC) and Bacillus spp. in wheat flour. Wet gluten contents and the stability time reached the maximum when treated for 20 s. The viscosity of starch increased significantly after treatment due to the increased of damaged starch. The contents of secondary structure were altered to some extent, which was because that the ordered network structure of gluten protein broken. Furthermore, compared with the control, texture properties of FWN were enhanced significantly at 20 s, and the darkening rate of FWN was greatly inhibited due to the low polyphenol oxidase (PPO) activity. Consequently, the most suitable treatment was 500 W for 20 s, providing a basis for the application of NTP in flour products. 相似文献
86.
飞机从一个航段飞向下一个航段时,需要对下个航段是否激活进行判断.提出了一种新的飞行计划航段自动激活方法,通过获取飞机当前位置及其磁差,并结合临近的3个航路点对应位置的磁差经纬度,分别计算3个航路点与飞机位置对应的磁航向角,通过磁航向角之间做差进行比较,进而判断是否被激活.算法推导完成后,通过基于模型的系统工程工具SCADE SUITE进行了建模,并结合杰普逊航图进行了实际数据采样与仿真.仿真结果表明:该航段自动激活方法能够有效稳定地激活下一航段,比传统方法计算简便,方法实用有效.已在实际飞行中成功应用,达到了预期效果. 相似文献
87.
Xiao-Mei Sha Li-Jun Zhang Wen-Mei Chen Guang-Yao Wang Jin-Lin Li Zi-Zi Hu Zong-Cai Tu 《International Journal of Food Science & Technology》2022,57(3):1573-1586
Thermal action in extraction process had effects on characteristic tryptic peptides identification and gelling properties of porcine gelatin. SDS-PAGE, HPLC-LTQ/Orbitrap high-resolution mass spectrometry, texture analyser and rheometer were used to evaluate collagen depolymerisation degree, characteristic tryptic peptides and gelling properties of gelatins prepared in various thermal actions. Results showed that with increasing temperature and time, depolymerisation degree enlarged, while gel strength, gelling and melting temperature decreased. Mass spectra showed that 47 and 49 common characteristic tryptic peptides were identified in gelatins extracted at 50 °C and 100 °C with various times, respectively. Moreover, 34 common characteristic tryptic peptides were identified in all gelatin samples. Further comparison between this work and our previous investigations yielded 20 common characteristic tryptic peptides, which stably exist in various thermal actions. These common characteristic tryptic peptides may be very helpful for the accurate authentication of porcine gelatin. 相似文献
88.
回转式空气预热器冷端传热元件的低温腐蚀、堵灰现象在国内外非常普遍,且受到众多电厂的关注,该问题会严重影响到锅炉的安全运行,导致诸如排烟温度增高、热风温度降低、阻力增大、漏风率上升等问题。根里奇·阿奇舒勒创立的TRIZ理论是一种综合的创新方法,可促进发明创造并得到优异的创新产品,它能够帮助我们系统地分析问题,发现问题的本质以及矛盾,从而得到问题实质解。本文针对回转式空气预热器低温腐蚀以及堵灰问题,采用TRIZ理论进行了深入分析。 相似文献
89.
90.
Xuewu Li Lin Zhang Tian Shi Weining Yu Jinhui Shao Xuegang Zhou Yuxing He Binbin Zhang 《工业材料与腐蚀》2021,72(5):951-959
Ti-based amorphous metallic glasses have excellent mechanical, physical, and chemical properties, which is an important development direction and research hotspot of metal composite reinforcement. As a stable, simple, efficient, and large-scale preparation technology of metallic powders, the gas atomization process provides an effective way of preparing amorphous metallic glasses. In this study, the controllable fabrication of a Ti-based amorphous powder, with high efficiency, has been realized by using gas atomization. The scanning electron microscope, energy-dispersive spectrometer, and X-ray diffraction are used to analyze surface morphology, element distribution, and phase structure, respectively. A microhardness tester is used to measure the mechanical property. An electrochemical workstation is used to characterize corrosion behavior. The results show that as-prepared microparticles are more uniform and exhibit good amorphous characteristics. The mechanical test shows that the hardness of amorphous powder is significantly increased as compared with that before preparation, which has the prospect of being an important part of engineering reinforced materials. Further electrochemical measurement shows that the corrosion resistance of the as-prepared sample is also significantly improved. This study has laid a solid foundation for expanding applications of Ti-based metallic glasses, especially in heavy-duty and corrosive domains. 相似文献