全文获取类型
收费全文 | 1535345篇 |
免费 | 29043篇 |
国内免费 | 7826篇 |
专业分类
电工技术 | 35266篇 |
技术理论 | 1篇 |
综合类 | 7263篇 |
化学工业 | 274693篇 |
金属工艺 | 65707篇 |
机械仪表 | 44212篇 |
建筑科学 | 47199篇 |
矿业工程 | 11790篇 |
能源动力 | 50852篇 |
轻工业 | 113461篇 |
水利工程 | 15835篇 |
石油天然气 | 38393篇 |
武器工业 | 238篇 |
无线电 | 199047篇 |
一般工业技术 | 289050篇 |
冶金工业 | 172410篇 |
原子能技术 | 34322篇 |
自动化技术 | 172475篇 |
出版年
2021年 | 16543篇 |
2020年 | 12549篇 |
2019年 | 15168篇 |
2018年 | 17463篇 |
2017年 | 17028篇 |
2016年 | 22436篇 |
2015年 | 18171篇 |
2014年 | 29648篇 |
2013年 | 88923篇 |
2012年 | 37034篇 |
2011年 | 50334篇 |
2010年 | 44413篇 |
2009年 | 52682篇 |
2008年 | 46302篇 |
2007年 | 43572篇 |
2006年 | 45354篇 |
2005年 | 40350篇 |
2004年 | 42084篇 |
2003年 | 41952篇 |
2002年 | 40761篇 |
2001年 | 37672篇 |
2000年 | 36043篇 |
1999年 | 35374篇 |
1998年 | 48437篇 |
1997年 | 41041篇 |
1996年 | 36445篇 |
1995年 | 31288篇 |
1994年 | 29247篇 |
1993年 | 29167篇 |
1992年 | 26196篇 |
1991年 | 23298篇 |
1990年 | 23677篇 |
1989年 | 22723篇 |
1988年 | 21234篇 |
1987年 | 19494篇 |
1986年 | 18851篇 |
1985年 | 22171篇 |
1984年 | 22332篇 |
1983年 | 20250篇 |
1982年 | 19244篇 |
1981年 | 19392篇 |
1980年 | 17957篇 |
1979年 | 18446篇 |
1978年 | 17709篇 |
1977年 | 17483篇 |
1976年 | 18406篇 |
1975年 | 15982篇 |
1974年 | 15464篇 |
1973年 | 15573篇 |
1972年 | 12990篇 |
排序方式: 共有10000条查询结果,搜索用时 47 毫秒
131.
132.
Wireless Personal Communications - Multiple inputs multiple outputs (MIMO) is a reliable technique which can manage the increased wireless data traffic in the future generation of wireless... 相似文献
133.
Wireless Personal Communications - This paper summarizes the ongoing research initiatives based on the advanced multiple access techniques towards the fifth generation (5G) wireless communication... 相似文献
134.
Russian Engineering Research - The modernization of manufacturing by the comprehensive application of digital technology—in both production and management—is considered. Principles are... 相似文献
135.
Dr. Ying Wang Prof. Dr. Andrew Ewing 《Chembiochem : a European journal of chemical biology》2021,22(5):807-813
Exocytosis plays an essential role in the communication between cells in the nervous system. Understanding the regulation of neurotransmitter release during exocytosis and the amount of neurotransmitter content that is stored in vesicles is of importance, as it provides fundamental insights to understand how the brain works and how neurons elicit a certain behavior. In this minireview, we summarize recent progress in amperometric measurements for monitoring exocytosis in single cells and electrochemical cytometry measurements of vesicular neurotransmitter content in individual vesicles. Important steps have increased our understanding of the different mechanisms of exocytosis. Increasing evidence is firmly establishing that partial release is the primary mechanism of release in multiple cell types. 相似文献
136.
Stefano Mariani Antonino Amedeo La Mattina Alessandro Paghi Lucanos Strambini Giuseppe Barillaro 《Advanced functional materials》2021,31(26):2100774
Here, a fluoride-assisted route for the controlled in-situ synthesis of metal nanoparticles (NPs) (i.e., AgNPs, AuNPs) on polydimethylsiloxane (PDMS) is reported. The size and coverage of the NPs on the PDMS surface are modulated with time and over space during the synthetic process, leveraging the improved yield (10×) and faster kinetics (100×) of NP formation in the presence of F− ions, compared to fluoride-free approaches. This enables the maskless preparation of both linear and step gradients and patterns of NPs in 1D and 2D on the PDMS surface. As an application in flexible plasmonics/photonics, continuous and step-wise spatial modulations of the plasmonic features of PDMS slabs with 1D and 2D AgNP gradients on the surface are demonstrated. An excellent spatially resolved tuning of key optical parameters, namely, optical density from zero to 5 and extinction ratio up to 100 dB, is achieved with AgNP gradients prepared in AgF solution for 12 minutes; the performance are comparable to those of commercial dielectric/interference filters. When used as a rejection filter in optical fluorescence microscopy, the AgNP-PDMS slabs are able to reject the excitation laser at 405 nm and retain the green fluorescence of microbeads (100 µm) used as test cases. 相似文献
137.
Liangtao Yang Liang-Yin Kuo Juan Miguel López del Amo Prasant Kumar Nayak Katherine A. Mazzio Sebastian Maletti Daria Mikhailova Lars Giebeler Payam Kaghazchi Teófilo Rojo Philipp Adelhelm 《Advanced functional materials》2021,31(38):2102939
A known strategy for improving the properties of layered oxide electrodes in sodium-ion batteries is the partial substitution of transition metals by Li. Herein, the role of Li as a defect and its impact on sodium storage in P2-Na0.67Mn0.6Ni0.2Li0.2O2 is discussed. In tandem with electrochemical studies, the electronic and atomic structure are studied using solid-state NMR, operando XRD, and density functional theory (DFT). For the as-synthesized material, Li is located in comparable amounts within the sodium and the transition metal oxide (TMO) layers. Desodiation leads to a redistribution of Li ions within the crystal lattice. During charging, Li ions from the Na layer first migrate to the TMO layer before reversing their course at low Na contents. There is little change in the lattice parameters during charging/discharging, indicating stabilization of the P2 structure. This leads to a solid-solution type storage mechanism (sloping voltage profile) and hence excellent cycle life with a capacity of 110 mAh g-1 after 100 cycles. In contrast, the Li-free compositions Na0.67Mn0.6Ni0.4O2 and Na0.67Mn0.8Ni0.2O2 show phase transitions and a stair-case voltage profile. The capacity is found to originate from mainly Ni3+/Ni4+ and O2-/O2-δ redox processes by DFT, although a small contribution from Mn4+/Mn5+ to the capacity cannot be excluded. 相似文献
138.
Romero-Garcés A. Salles De Freitas R. Marfil R. Vicente-Chicote C. Martínez J. Inglés-Romero J. F. Bandera A. 《Multimedia Tools and Applications》2022,81(3):3603-3628
Multimedia Tools and Applications - The design of robots capable of operating autonomously in changing and unstructured environments, requires using complex software architectures in which,... 相似文献
139.
Belov M. I. Anashin D. V. Kabdin N. E. Storchevoy V. F. Sudnik Yu. A. 《Russian Engineering Research》2022,42(11):1110-1116
Russian Engineering Research - The stability of robot-mower motion in a specific direction is considered. The direction is regulated by means of an angular sensor and a programmable controller... 相似文献
140.
Revin A. A. Mikhaylova A. M. Konakov A. A. Tsyplenkov V. V. Shastin V. N. 《Semiconductors》2021,55(12):879-884
Semiconductors - The wave functions of electrons localized at P, As, and Sb shallow donors in Ge are calculated in the envelope function approximation taking into account valley–orbit... 相似文献