全文获取类型
收费全文 | 58188篇 |
免费 | 6362篇 |
国内免费 | 3878篇 |
专业分类
电工技术 | 4427篇 |
技术理论 | 1篇 |
综合类 | 5183篇 |
化学工业 | 8667篇 |
金属工艺 | 3458篇 |
机械仪表 | 4074篇 |
建筑科学 | 4683篇 |
矿业工程 | 1916篇 |
能源动力 | 1815篇 |
轻工业 | 5455篇 |
水利工程 | 1537篇 |
石油天然气 | 2399篇 |
武器工业 | 654篇 |
无线电 | 6351篇 |
一般工业技术 | 5995篇 |
冶金工业 | 2166篇 |
原子能技术 | 929篇 |
自动化技术 | 8718篇 |
出版年
2024年 | 288篇 |
2023年 | 853篇 |
2022年 | 2000篇 |
2021年 | 2747篇 |
2020年 | 2022篇 |
2019年 | 1574篇 |
2018年 | 1611篇 |
2017年 | 1842篇 |
2016年 | 1747篇 |
2015年 | 2539篇 |
2014年 | 3245篇 |
2013年 | 3781篇 |
2012年 | 4428篇 |
2011年 | 4620篇 |
2010年 | 4223篇 |
2009年 | 4205篇 |
2008年 | 4251篇 |
2007年 | 4009篇 |
2006年 | 3680篇 |
2005年 | 2912篇 |
2004年 | 2147篇 |
2003年 | 1721篇 |
2002年 | 1947篇 |
2001年 | 1601篇 |
2000年 | 1251篇 |
1999年 | 850篇 |
1998年 | 477篇 |
1997年 | 375篇 |
1996年 | 331篇 |
1995年 | 278篇 |
1994年 | 212篇 |
1993年 | 160篇 |
1992年 | 95篇 |
1991年 | 83篇 |
1990年 | 61篇 |
1989年 | 58篇 |
1988年 | 45篇 |
1987年 | 34篇 |
1986年 | 27篇 |
1985年 | 20篇 |
1984年 | 7篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 15篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1976年 | 2篇 |
1959年 | 9篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
油液监测是判断设备健康状况和提供设备故障隐患预警的有效方法。综述了用于监测润滑油中磨损颗粒的最新各类在线传感器的基本原理,包括批量磁吸附式传感器、微流体电容传感器、金属扫描传感器、双层平面线圈传感器、超声波传感器和光学传感器等,并讨论各种传感方法的优缺点以及未来发展面临的挑战;指出了高通量、高灵敏度、能区别金属与非金属磨粒、可采集磨粒图像信息的集成式传感器是未来研究的重点,集成式、智能化、无线传输的传感器是未来研发方向。 相似文献
2.
Chenchen Zhou Jia Man Haibo Yu He Xia Luming Man Bin Qi Jianfeng Li 《Ceramics International》2021,47(8):10866-10872
Ceramic microparticles have great potentials in various fields such as materials engineering, biotechnology, microelectromechanical systems, etc. Morphology of the microparticle performs an important role on their application. To date, it remains difficult to find an effective and controllable way for fabricating nonspherical ceramic microparticles with 3D features. This work demonstrates a method that combines UV light lithography and single emulsion opaque-droplet-templated microfluidic molding to prepare the crescent-shaped ceramic microparticles. By tailoring the intensity of UV light and flow rate of fluid, the shapes of microparticles are accordingly tuned. Therefore, varieties of crescent-shaped microparticles and their variations have been fabricated. After sintering, the crescent-shaped alumina ceramic microparticles were obtained. Benefitting from the light absorption and scattering behavior of most ceramic nanoparticles, this system can serve as a general platform to produce crescent-shaped microparticles made from different materials, and hold great potentials for applications in microrobotics, structural materials in MEMS, and biotechnology. 相似文献
3.
4.
Jia Dai Xiang Cheng Xiaofeng Li Zhisheng Wang Yufeng Wang Jing Zheng Jun Liu Jiawei Chen Changjin Wu Jinyao Tang 《Advanced functional materials》2021,31(48):2106204
Synthetic active matters are perfect model systems for non-equilibrium thermodynamics and of great potential for novel biomedical and environmental applications. However, most applications are limited by the complicated and low-yield preparation, while a scalable synthesis for highly functional microswimmers is highly desired. In this paper, an all-solution synthesis method is developed where the gold-loaded titania-silica nanotree can be produced as a multi-functional self-propulsion microswimmer. By applying light, heat, and electric field, the Janus nanotree demonstrated multi-mode self-propulsion, including photochemical self-electrophoresis by UV and visible light radiation, thermophoresis by near-infrared light radiation, and induced-charge electrophoresis under AC electric field. Due to the scalable synthesis, the Janus nanotree is further demonstrated as a high-efficiency, low-cost, active adsorbent for water decontamination, where the toxic mercury ions can be reclaimed with enhanced efficiency. 相似文献
5.
The slight-alkalization of generator internal cooling water (GICW) is widely used to inhibit the corrosion of hollow copper conductor and thereby ensure the safe operation of the generator. CO2 inleakage is increasingly identified as a potential security risk for GICW system. In this paper, the influence of CO2 inleakage on the slight-alkalization of GICW was theoretically discussed. Based on the equilibriums of the CO2-NaOH-H2O system, CO2 inleakage saturation was derived to quantify the amount of the dissolved CO2 in GICW. This parameter can be directly calculated with the measured conductivity and the [Na+] of GICW. The influence of CO2 inleakage on the slight-alkalization conditioning of GICW and the measurement of its water quality parameters were then analyzed. The more severe the inleakage, the narrower the water quality operation ranges of GICW, resulting in the more difficult the slight-alkalization conditioning of GICW. The temperature calibrations of the conductivity and the pH value of GICW show non-linear correlations with the amount of CO2 inleakage and the NaOH dosage. This study provides insights into the influence of CO2 inleakage on the slight-alkalization of GICW, which can serve as the theoretical basis for the actual slight-alkalization when CO2 inleakage occurs. 相似文献
6.
三唑并嘧啶磺酰胺类除草剂——五氟磺草胺 总被引:1,自引:0,他引:1
综述了新型三唑并嘧啶磺酰胺类除草剂五氟磺草胺的理化性质、毒性、分析方法、加工及应用,详细介绍了其合成工艺路线、相关专利与开发进展。 相似文献
8.
9.
Nitrile rubber (NBR) blends with excellent performance have always been a hot research topic in petroleum field. Due to the excellent performance and compatibility of polyamide 6 (PA6), it provides an opportunity for the preparation of high-performance NBR/PA6 blends. In this article, NBR/PA6 blends were prepared by the three-step molding process. Experimentally, it was found that PA6 has a prominent reinforcement effect in NBR matrix. The variation of this mechanical property was investigated from different aspects of the crystal structure, crystallinities, phase morphology, and so on. It can be cleared that the formation of fibrous structure of PA6 phase is the main factor for reinforcement of the polymer blends. Meanwhile, the formation mechanism of the special phase structure induced by the three-step process is deeply expounded and its structural evolution schematic is established. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47472. 相似文献
10.
进入更广泛的历史语境探讨清乾隆时期镜清斋假山的营造思路,追溯至晚明江南的两种假山营造来源.在整体构思上,承续了17世纪前期张南垣所创的追求画意真山的"天然"假山;而在局部营造中,则采纳了16世纪后期盛行的追求胜景无穷的"人巧"假山.除镜清斋之外,在稍晚的苏州环秀山庄假山中也有显著表达,是清代假山发展高峰的体现.清末和1970年代对该假山的两次改造,未能很好理解原初的思路取向,一定程度上损害了当初追求的山意. 相似文献