全文获取类型
收费全文 | 11537篇 |
免费 | 1342篇 |
国内免费 | 840篇 |
专业分类
电工技术 | 310篇 |
技术理论 | 1篇 |
综合类 | 1091篇 |
化学工业 | 965篇 |
金属工艺 | 1554篇 |
机械仪表 | 1145篇 |
建筑科学 | 1028篇 |
矿业工程 | 255篇 |
能源动力 | 231篇 |
轻工业 | 433篇 |
水利工程 | 223篇 |
石油天然气 | 220篇 |
武器工业 | 140篇 |
无线电 | 808篇 |
一般工业技术 | 2165篇 |
冶金工业 | 769篇 |
原子能技术 | 100篇 |
自动化技术 | 2281篇 |
出版年
2024年 | 32篇 |
2023年 | 205篇 |
2022年 | 228篇 |
2021年 | 365篇 |
2020年 | 404篇 |
2019年 | 374篇 |
2018年 | 348篇 |
2017年 | 387篇 |
2016年 | 398篇 |
2015年 | 384篇 |
2014年 | 605篇 |
2013年 | 721篇 |
2012年 | 718篇 |
2011年 | 800篇 |
2010年 | 646篇 |
2009年 | 683篇 |
2008年 | 656篇 |
2007年 | 856篇 |
2006年 | 711篇 |
2005年 | 609篇 |
2004年 | 555篇 |
2003年 | 476篇 |
2002年 | 416篇 |
2001年 | 350篇 |
2000年 | 310篇 |
1999年 | 273篇 |
1998年 | 218篇 |
1997年 | 190篇 |
1996年 | 143篇 |
1995年 | 125篇 |
1994年 | 107篇 |
1993年 | 78篇 |
1992年 | 62篇 |
1991年 | 48篇 |
1990年 | 48篇 |
1989年 | 45篇 |
1988年 | 31篇 |
1987年 | 12篇 |
1986年 | 11篇 |
1985年 | 13篇 |
1984年 | 15篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1975年 | 3篇 |
1966年 | 2篇 |
1964年 | 3篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
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
2.
Manik Chandra Biswas Samit Chakraborty Abhishek Bhattacharjee Zaheeruddin Mohammed 《Advanced functional materials》2021,31(19):2100257
Shape memory materials (SMMs) in 3D printing (3DP) technology garnered much attention due to their ability to respond to external stimuli, which direct this technology toward an emerging area of research, “4D printing (4DP) technology.” In contrast to classical 3D printed objects, the fourth dimension, time, allows printed objects to undergo significant changes in shape, size, or color when subjected to external stimuli. Highly precise and calibrated 4D materials, which can perform together to achieve robust 4D objects, are in great demand in various fields such as military applications, space suits, robotic systems, apparel, healthcare, sports, etc. This review, for the first time, to the best of the authors’ knowledge, focuses on recent advances in SMMs (e.g., polymers, metals, etc.) based wearable smart textiles and fashion goods. This review integrates the basic overview of 3DP technology, fabrication methods, the transition of 3DP to 4DP, the chemistry behind the fundamental working principles of 4D printed objects, materials selection for smart textiles and fashion goods. The central part summarizes the effect of major external stimuli on 4D textile materials followed by the major applications. Lastly, prospects and challenges are discussed, so that future researchers can continue the progress of this technology. 相似文献
3.
4.
By leveraging the secret data coding using the remainder storage based exploiting modification direction (RSBEMD), and the pixel change operation recording based on multi-segment left and right histogram shifting, a novel reversible data hiding (RHD) scheme is proposed in this paper. The secret data are first encoded by some specific pixel change operations to the pixels in groups. After that, multi-segment left and right histogram shifting based on threshold manipulation is implemented for recording the pixel change operations. Furthermore, a multiple embedding policy based on chess board prediction (CBP) and threshold manipulation is put forward, and the threshold can be adjusted to achieve adaptive data hiding. Experimental results and analysis show that it is reversible and can achieve good performance in capacity and imperceptibility compared with the existing methods. 相似文献
5.
Wesley P. Chan Hiroto Mizohana Xiangyu Chen Yasuto Shiigi Yoshiyuki Yamanoue Masaki Nagatsuka Masayuki Inaba 《野外机器人技术杂志》2019,36(1):17-33
The use of field robots can greatly decrease the amount of time, effort, and associated risk compared to if human workers were to carryout certain tasks such as disaster response. However, transportability and reliability remain two main issues for most current robot systems. To address the issue of transportability, we have developed a lightweight modularizable platform named AeroArm. To address the issue of reliability, we utilize a multimodal sensing approach, combining the use of multiple sensors and sensor types, and the use of different detection algorithms, as well as active continuous closed‐loop feedback to accurately estimate the state of the robot with respect to the environment. We used Challenge 2 of the 2017 Mohammed Bin Zayed International Robotics Competition as an example outdoor manipulation task, demonstrating the capabilities of our robot system and approach in achieving reliable performance in the fields, and ranked fifth place internationally in the competition. 相似文献
6.
Ken Kanazawa Shoji Yoshida Hidemi Shigekawa Shinji Kuroda 《Science and Technology of Advanced Materials》2015,16(1)
The reconstructed surface structure of the II–VI semiconductor ZnTe (110), which is a promising material in the research field of semiconductor spintronics, was studied by scanning tunneling microscopy/spectroscopy (STM/STS). First, the surface states formed by reconstruction by the charge transfer of dangling bond electrons from cationic Zn to anionic Te atoms, which are similar to those of IV and III–V semiconductors, were confirmed in real space. Secondly, oscillation in tunneling current between binary states, which is considered to reflect a conformational change in the topmost Zn–Te structure between the reconstructed and bulk-like ideal structures, was directly observed by STM. Third, using the technique of charge injection, a surface atomic structure was successfully fabricated, suggesting the possibility of atomic-scale manipulation of this widely applicable surface of ZnTe. 相似文献
7.
We model developable surfaces by wrapping a planar figure around cones and cylinders. Complicated developables can be constructed by successive mappings using cones and cylinders of different sizes and shapes. We also propose an intuitive control mechanism, which allows a user to select an arbitrary point on the planar figure and move it to a new position. Numerical techniques are then used to find a cone or cylinder that produces the required mapping. Several examples demonstrate the effectiveness of our technique. 相似文献
9.
针对反射面成型的复杂影响因素,提出平面桁架构建的定日镜面形支撑结构优化技术路线. 利用模拟仿真、数值计算和优化算法等方法,解析20 m2定日镜面形定义技术路线的4个组成环节:面形规格及宽高比、上弦杆的截面矩、平面桁架组间距的最优值、机加工中工艺控制要点的量化. 试制小型定日镜进行实验,分析光斑形状和能流密度分布特性,并与理想球面形光斑比较,两者的拟合优度大于0.98. 实验结果表明,当反射镜宽高比取1.2,上弦杆截面矩取40 000 mm4,桁架组间距取950 mm,上弦杆和斜杆的开孔公差小于0.9 mm时,反射面形的质量提升. 研究从原理和实践上证明了该优化技术路线的可行性. 相似文献
10.