全文获取类型
收费全文 | 3549篇 |
免费 | 467篇 |
国内免费 | 216篇 |
专业分类
电工技术 | 139篇 |
综合类 | 228篇 |
化学工业 | 309篇 |
金属工艺 | 86篇 |
机械仪表 | 77篇 |
建筑科学 | 221篇 |
矿业工程 | 64篇 |
能源动力 | 1139篇 |
轻工业 | 54篇 |
水利工程 | 99篇 |
石油天然气 | 68篇 |
武器工业 | 14篇 |
无线电 | 690篇 |
一般工业技术 | 565篇 |
冶金工业 | 61篇 |
原子能技术 | 21篇 |
自动化技术 | 397篇 |
出版年
2024年 | 16篇 |
2023年 | 202篇 |
2022年 | 286篇 |
2021年 | 292篇 |
2020年 | 280篇 |
2019年 | 286篇 |
2018年 | 205篇 |
2017年 | 203篇 |
2016年 | 149篇 |
2015年 | 149篇 |
2014年 | 212篇 |
2013年 | 215篇 |
2012年 | 228篇 |
2011年 | 219篇 |
2010年 | 151篇 |
2009年 | 163篇 |
2008年 | 133篇 |
2007年 | 148篇 |
2006年 | 115篇 |
2005年 | 99篇 |
2004年 | 63篇 |
2003年 | 80篇 |
2002年 | 65篇 |
2001年 | 49篇 |
2000年 | 58篇 |
1999年 | 30篇 |
1998年 | 32篇 |
1997年 | 30篇 |
1996年 | 8篇 |
1995年 | 13篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1984年 | 3篇 |
1983年 | 1篇 |
排序方式: 共有4232条查询结果,搜索用时 31 毫秒
81.
Electrocatalysis: Morphology and Structure Engineering in Nanofiber Reactor: Tubular Hierarchical Integrated Networks Composed of Dual Phase Octahedral CoMn2O4/Carbon Nanofibers for Water Oxidation (Small 26/2017)
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
82.
H+ ions with various fluences are implanted into x and z-cut KTP crystals to achieve KTP film. Post-implantation annealing under different temperature is imposed on the samples to induce layer splitting and surface morphology modification. Layer exfoliation is observed in freestanding z-cut samples. Layer splitting is obtained using bonding method in x-cut sample implanted with 117 keV H+ ions at ion fluence of 6 × 1016 ions/cm2. Optical microscopy, scanning electron microscope and atomic force microscopy are used to observe splitting phenomenon. Rutherford backscattering spectroscopy/channeling method is employed to measure lattice damage and to investigate the relationship between implantation-induced defects and layer splitting. 相似文献
83.
综述了胀断加工技术对连杆材料的特殊要求及胀断连杆用材料的发展现状,探讨了非调质钢胀断连杆组织性能控制的原理与策略。最后提出了扩大非调质钢应用的建议,强调应加强基础研究,揭示非调质钢的材料特性,特别是组织性能定量关系;强化"产学研用"结合,采用控锻控冷技术实现非调质钢胀断连杆组织性能的精确柔性系统控制。 相似文献
84.
Retracted: Dual Effects of Nanostructuring and Oxygen Vacancy on Photoelectrochemical Water Oxidation Activity of Superstructured and Defective Hematite Nanorods
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Lei Wang Kyle Marcus Xiaojuan Huang Zhiqiang Shen Yang Yang Yingpu Bi 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(14)
An Ar atmospheric treatment is rationally used to etch and activate hematite nanoflakes (NFs) as photoanodes toward enhanced photoelectrochemical water oxidation. The formation of a highly ordered hematite nanorods (NRs) array containing a high density of oxygen vacancy is successfully prepared through in situ reduction of NFs in Ar atmosphere. Furthermore, a hematite (104) plane and an iron suboxide layer at the absorber/back‐contact interface are formed. The material defects produced by a thermal oxidation method can be critical for the morphology transformation from 2D NFs to 1D NRs. The resulting hematite NR photoanodes show high efficiency toward solar water splitting with improved light harvesting capabilities, leading to an enhanced photoresponse due to the artificially formed oxygen vacancies. 相似文献
85.
We propose a compact split-step finite difference method to solve the nonlinear Schrödinger equations with constant and variable coefficients. This method improves the accuracy of split-step finite difference method by introducing a compact scheme for discretization of space variable while this improvement does not reduce the stability range and does not increase the computational cost. This method also preserves some conservation laws. Numerical tests are presented to confirm the theoretical results for the new numerical method by using the cubic nonlinear Schrödinger equation with constant and variable coefficients and Gross-Pitaevskii equation. 相似文献
86.
87.
88.
A model, a heuristic and a decision support system to solve the scheduling problem of an earth observing satellite constellation 总被引:1,自引:0,他引:1
China plans to launch four small optical satellites and four small SAR satellites to form a natural disaster monitoring constellation. Data can be obtained by the constellation in all weather conditions for disaster alert and environmental damage analysis. The scheduling problem for the constellation consists of selecting and timetabling the observation activities to acquire the requested images of the earth surface and scheduling the download activities to transmit the image files to a set of ground stations. The scheduling problem is required to be solved every day in a typical 1-day horizon and it must respect complex satellite operational constraints as well as request preferences, such as visibility time windows, transition time between consecutive observations or downloads, memory capacity, energy capacity, polygon target requests and priorities. The objective is to maximize the rewards of the images taken and transmitted. We present a nonlinear model of the scheduling problem, develop a priority-based heuristic with conflict-avoided, limited backtracking and download-as-needed features, which produces satisfactory feasible plans in a very short time. A decision support system based on the model and the heuristic is also provided. The system performance shows a significant improvement with respect to faster and better scheduling of an earth observing satellite constellation. 相似文献
89.
This paper presents an interpolating ternary butterfly subdivision scheme for triangular meshes based on a 1–9 splitting operator. The regular rules are derived from a C2 interpolating subdivision curve, and the irregular rules are established through the Fourier analysis of the regular case. By analyzing the eigenstructures and characteristic maps, we show that the subdivision surfaces generated by this scheme is C1 continuous up to valence 100. In addition, the curvature of regular region is bounded. Finally we demonstrate the visual quality of our subdivision scheme with several examples. 相似文献
90.