全文获取类型
收费全文 | 41709篇 |
免费 | 5965篇 |
国内免费 | 2392篇 |
专业分类
电工技术 | 15771篇 |
技术理论 | 2篇 |
综合类 | 3465篇 |
化学工业 | 1411篇 |
金属工艺 | 1288篇 |
机械仪表 | 4477篇 |
建筑科学 | 1576篇 |
矿业工程 | 990篇 |
能源动力 | 1120篇 |
轻工业 | 709篇 |
水利工程 | 643篇 |
石油天然气 | 907篇 |
武器工业 | 432篇 |
无线电 | 7299篇 |
一般工业技术 | 3631篇 |
冶金工业 | 683篇 |
原子能技术 | 278篇 |
自动化技术 | 5384篇 |
出版年
2024年 | 134篇 |
2023年 | 713篇 |
2022年 | 1038篇 |
2021年 | 1517篇 |
2020年 | 1711篇 |
2019年 | 1328篇 |
2018年 | 1293篇 |
2017年 | 1662篇 |
2016年 | 1713篇 |
2015年 | 2031篇 |
2014年 | 3015篇 |
2013年 | 2609篇 |
2012年 | 3650篇 |
2011年 | 3682篇 |
2010年 | 2658篇 |
2009年 | 2629篇 |
2008年 | 2494篇 |
2007年 | 2828篇 |
2006年 | 2513篇 |
2005年 | 2083篇 |
2004年 | 1669篇 |
2003年 | 1322篇 |
2002年 | 976篇 |
2001年 | 935篇 |
2000年 | 727篇 |
1999年 | 611篇 |
1998年 | 489篇 |
1997年 | 405篇 |
1996年 | 347篇 |
1995年 | 283篇 |
1994年 | 232篇 |
1993年 | 165篇 |
1992年 | 136篇 |
1991年 | 97篇 |
1990年 | 80篇 |
1989年 | 92篇 |
1988年 | 41篇 |
1987年 | 24篇 |
1986年 | 21篇 |
1985年 | 16篇 |
1984年 | 25篇 |
1983年 | 18篇 |
1982年 | 21篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 173 毫秒
51.
为查清糯东煤矿11705工作面内部煤厚变化,并圈出工作面瓦斯治理高风险区域,为工作面安全高效生产提供指导,采用槽波地震透射法对11705工作面进行探测。联合槽波速度解释与能量解释两种方法,辨析透射槽波的质量,将质量差的槽波射线分别绘制在平面图上,采用射线交汇的方法划分工作面的开采风险分布区域。探测成果与实验室中解吸法的瓦斯测定成果进行了对比,结果表明,煤与瓦斯突出矿井槽波速度与瓦斯富集区存在一定相关性,在槽波高速区、波速急剧变化带或高低速相间分布区,瓦斯含量可能较高;被四周高速区所包围的低速区域瓦斯含量较高。上述结论为国内同类型矿井瓦斯富集区探测提供了借鉴。 相似文献
52.
Wenhao Ran Lili Wang Shufang Zhao Depeng Wang Ruiyang Yin Zheng Lou Guozhen Shen 《Advanced materials (Deerfield Beach, Fla.)》2020,32(16):1908419
Infrared (IR) photodetectors are a key optoelectronic device and have thus attracted considerable research attention in recent years. Photosensitivity is an increasingly important device performance parameter for nanoscale photodetectors and image sensors, as it determines the ultimate imaging quality and contrast. However, photosensitivities of state-of-the-art low-dimensional nanostructure-based IR detectors are considerably low, limiting their practical applications. Herein, a biomimetic IR detection amplification (IRDA) system that boosts photosensitivity by several orders of magnitude by introducting nanowire field effect transistors (FETs), resulting in a peak photosensitivity of 7.6 × 104 under an illumination of 1342 nm, is presented. Consequently, high-contrast imaging of IR light is obtained on the flexible IRDA arrays. The image information can be then trained and recognized by an artificial neural network for higher image-recognition efficiency. This work provides a new perspective for developing high-performance IR imaging systems, and is expected to undoubtedly enlighten future work on artificial intelligence and biorobotic systems. 相似文献
53.
Stain density is an important parameter for optimising the quality of ultrastructural data obtained from several types of 3D electron microscopy techniques, including serial block-face electron microscopy (SBEM), and focused ion beam scanning electron microscopy (FIB-SEM). Here, we show how some straightforward measurements in the TEM can be used to determine the stain density based on a simple expression that we derive. Numbers of stain atoms per unit volume are determined from the measured ratio of the bright-field intensities from regions of the specimen that contain both pure embedding material and the embedded biological structures of interest. The determination only requires knowledge of the section thickness, which can either be estimated from the microtome setting, or from low-dose electron tomography, and the elastic scattering cross section for the heavy atoms used to stain the specimen. The method is tested on specimens of embedded blood platelets, brain tissue and liver tissue. 相似文献
54.
研究一种基于理论计算与CFD仿真的胀圈密封环轴槽间隙尺寸设计方法。基于流体力学的基本方程,建立胀圈密封流场的数学模型;结合实际工况与使用要求,确定胀圈密封环与轴槽径向间隙、轴向间隙及配流衬套与旋转轴之间的间隙尺寸的约束范围;建立流场的计算流体力学模型,通过正交试验设计,分析影响胀圈密封性能的高灵敏度因素;以密封泄漏量最小为目标函数,选取最佳的轴槽间隙设计参数。结果表明,研究的3种间隙中,相比于胀圈密封环与轴槽的径向间隙、轴向间隙,配流衬套与旋转轴之间的间隙对密封环的泄漏量影响更为显著,当配流衬套与旋转轴之间的间隙增大,泄漏量也随之增大。 相似文献
55.
Qianwen Liu Guofeng Zhang Nan Chen Xixi Feng Chengzhi Wang Jiaqi Wang Xuting Jin Liangti Qu 《Advanced functional materials》2020,30(38)
Humans live today in a high‐tech and informationalized society. With the development of the emerging electronic information age, various electronic systems are inclined to be multifunctional and miniaturized. It is urgent to develop “small and powerful” micro‐batteries with flexibility and high electrochemical performance to meet the diverse needs of microelectronic components. However, low electrochemical performance exists in traditional microenergy storage devices, which fail to satisfy the energy needs for microdevices. Here, for the first time, a planar integrated flexible rechargeable dual‐ion microbattery (DIMB) is reported, which is fabricated from an interdigital pattern of graphite as an electrode and lithium hexafluorophosphate as an electrolyte. As a microbattery, the DIMB exhibits a high reversible capacity of 56.50 mAh cm?3, and excellent cycle stability with 90% capacity retention after 300 cycles under a high working voltage. The application of DIMB in microdevices, such as light‐emitting diodes (LEDs), digital electronic game consoles, and electrochromic glasses is also investigated, fully demonstrating its “small and powerful” performance. The integrated DIMB is a high‐voltage microdevice that reaches a nonpareil discharge voltage of about 100 V and a charging capacity of 102 mAh g?1. This dual ion‐based flexible microbattery could become a promising candidate for energy storage and conversion components in next‐generation microelectronic devices and integrated electronic devices. 相似文献
56.
57.
在介绍国内外输电线路现有机器人研究基础上,针对配电线路绝缘修复领域短板,开发了一套能够在线修复配电线路绝缘皮损伤的包裹机器人。首先,对绝缘包裹机器人的机械结构进行了设计研究,包括行走装置、升降装置和柔性输送与包裹装置;然后,开发了相应的控制系统,包括无线通讯、视觉系统等,并对其进行了抗干扰试验和耐压试验,试验结果合格;最后,通过现场绝缘包裹测试完成了机器人的功能性与可靠性验证。本项目所研发的机器人突破了在线修复、柔性包裹等技术瓶颈,解决了人工修复带来的一系列问题。样机通过现场带电包裹试验,绝缘包裹效果符合行业标准要求,达到了预期效果。 相似文献
58.
Md Sazzadur Rahman MD Nahin Islam Shiblee Kumkum Ahmed Ajit Khosla Jun Ogawa Masaru Kawakami Hidemitsu Furukawa 《大分子材料与工程》2020,305(9)
In this work, 3D printable gel polymer electrolytes (GPEs) based on N,N‐dimethylacrylamide (DMAAm) and polyvinylidene fluoride (PVDF) in lithium chloride containing ethylene glycol solution are synthesized and their physicochemical properties are investigated. 3D printing is carried out with a customized stereolithography type 3D gel printer named “Soft and Wet Intelligent Matter‐Easy Realizer” and free forming GPE samples having variable shapes and sizes are obtained. Printed PVDF/PDMAAm‐based GPEs exhibit tunable mechanical properties and favorable thermal stability. Electrochemical proprieties of the printed GPEs are carried out via impedance spectroscopy in the temperature range of 25–90 °C by varying PVDF content. Ionic conductivity as high as 6.5 × 10?4 S cm?1 is achieved at room temperature for GPE containing low PVDF content (5 wt%) and conductivity of the GPEs is increased as temperature rises. 相似文献
59.
与传统的涂覆、沉积等加工手段相比,使用3D打印技术可制造复杂立体功能结构的传感器,将3D打印与柔性传感技术结合可以促进未来生物医疗、人工智能等领域的发展。本文介绍了国内外基于3D打印技术制造柔性传感器的最新进展,其中包括聚酰亚胺等多种基底材料、纳米金属等多种打印传感材料;按照熔融沉积、黏弹性墨水沉积、粉末烧结熔化、还原光聚合和材料喷射的制造原理分别阐述了多种传感器的材料选择、成型特点,并对制造方法进行总结分析。虽然3D打印制造柔性传感器件存在着缺乏行业标准及多种类打印材料等问题,但经过不断创新与发展,3D打印将成为柔性传感领域极佳的制造手段。 相似文献
60.
Wireless Power Transmission is an emerging technology that enables the transmission of electricity without the use of artificial conducting mediums. Lack of significant technological breakthroughs widely affected its progress. In this paper, we analyze the early progress of WPT and attempt to forecast its growth using Pearl curve model. Fisher-Pry substitution model analysis indicates that technology substitution of wired transmission has just begun and half the substitution will be over by 2028. We conducted patent landscaping to identify hot domains and specific technology areas. Implications for technology developers and manufacturers, electric utility providers and national policymakers are also identified. 相似文献