全文获取类型
收费全文 | 21528篇 |
免费 | 1401篇 |
国内免费 | 442篇 |
专业分类
电工技术 | 1087篇 |
技术理论 | 5篇 |
综合类 | 1053篇 |
化学工业 | 3758篇 |
金属工艺 | 971篇 |
机械仪表 | 1240篇 |
建筑科学 | 1349篇 |
矿业工程 | 545篇 |
能源动力 | 609篇 |
轻工业 | 1224篇 |
水利工程 | 303篇 |
石油天然气 | 1141篇 |
武器工业 | 131篇 |
无线电 | 2865篇 |
一般工业技术 | 2883篇 |
冶金工业 | 1045篇 |
原子能技术 | 227篇 |
自动化技术 | 2935篇 |
出版年
2025年 | 44篇 |
2024年 | 512篇 |
2023年 | 423篇 |
2022年 | 575篇 |
2021年 | 802篇 |
2020年 | 675篇 |
2019年 | 619篇 |
2018年 | 612篇 |
2017年 | 625篇 |
2016年 | 609篇 |
2015年 | 708篇 |
2014年 | 922篇 |
2013年 | 1236篇 |
2012年 | 1144篇 |
2011年 | 1296篇 |
2010年 | 1001篇 |
2009年 | 1047篇 |
2008年 | 1020篇 |
2007年 | 978篇 |
2006年 | 1028篇 |
2005年 | 921篇 |
2004年 | 624篇 |
2003年 | 605篇 |
2002年 | 526篇 |
2001年 | 448篇 |
2000年 | 535篇 |
1999年 | 590篇 |
1998年 | 539篇 |
1997年 | 466篇 |
1996年 | 449篇 |
1995年 | 323篇 |
1994年 | 308篇 |
1993年 | 217篇 |
1992年 | 171篇 |
1991年 | 144篇 |
1990年 | 131篇 |
1989年 | 100篇 |
1988年 | 78篇 |
1987年 | 52篇 |
1986年 | 45篇 |
1985年 | 39篇 |
1984年 | 23篇 |
1983年 | 18篇 |
1982年 | 32篇 |
1981年 | 22篇 |
1980年 | 16篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1976年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
Haijun Tan Chunyue Pan Gang Wang Yingying Wu Yiping Zhang Yingping Zou Guipeng Yu Min Zhang 《Organic Electronics》2013,14(11):2795-2801
A series of organic dyes (POZ-2, POZ-3, POZ-4 and POZ-5) involving phenoxazine were synthesized as sensitizers for application in dye-sensitized solar cells (DSSCs). For comparison, three different electron donors namely 10-phenyl-10H-phe-nothiazine, 10-phenyl-10H-phenoxazine and triphenylamine were separately appended onto the 7-position of the model dye (POZ-2). The obtained four dyes exhibit considerably high values of conversion efficiencies of 6.6%, 7.8%, 7.1% and 6.4%, respectively, under the simulated AM1.5G conditions. The geometries of the dyes were optimized to gain insight into the molecular structure and electron distribution, and then the charge extraction and transient photovoltage decay measurements were further performed to understand the influence of electron donors on the photovoltaic behaviors. 相似文献
122.
From the detailed analysis of the dependence of threshold voltage shift and positive fixed charge/interface state generation on the stress time/temperature of negative bias temperature instability (NBTI) for various nitrogen concentrations at the oxide/Si interface, the mechanism of nitrogen-enhanced NBTI effect has been studied experimentally. The experimental results can be understood in terms of the reaction energies of the hydrogen trapping reactions at the interface, which are obtained from first-principles calculations. The calculations show that the nitrogen's lone-pair electrons can trap dissociated hydrogen species more easily than oxygen. From the experimental and theoretical studies, one can conclude that the roles of nitrogen in the NBTI are two folds, i.e., it provides more reaction sites, and it can also enhance the NBTI reaction by reducing the reaction energy. 相似文献
123.
The two-stage interconnection network is conceivably the most compact design for interconnecting small switches into a large switch. Switches so constructed typically can be controlled in the self-routing manner, because the route from an input to an output is unique. Different orderings of network input/output result in different versions of the two-stage interconnection network, two of which are known to preserve various classes of conditionally nonblocking switches. This paper adds Latin-square switches, rotators, reflectors, twisters, and untwisters to this set of classes with applications in load balancing, crosstalk-free optical switching, full connectivity among multiple users, etc. Knowledge of switch preservation under a certain style of multistage interconnection not only allows recursive construction of indefinitely large switches, but also provides insight, generality, and algorithmic flexibility in the construction 相似文献
124.
125.
Goh H. L. Tan K. K. Huang S. de Silva C. W. 《Industrial Informatics, IEEE Transactions on》2006,2(4):221-230
There is a growing trend in developing the wireless machine-to-machine (M2M) communication for factory automation. Currently, most wireless protocols for infrastructureless mobile ad-hoc networks focus on the mobility issue and are mainly suitable for narrowband radio devices. The mechanisms for route update and discovery that work well for wireless mobile ad-hoc networks prove to be redundant and instead add to processing overheads in a static wireless factory setting. This paper presents the development and implementation of a new wireless routing protocol, Bluewave, that caters specifically to wireless communication between machines in a factory setting. Bluewave utilizes features of Bluetooth technology when performing the route setup. The merits of the proposed protocol, in terms of shorter initialization time and route setup time, are duly discussed. A case study illustrating the application of Bluewave to an online condition-based maintenance scenario is presented. Experimental results obtained are furnished to show the viability of Bluewave in industrial automation 相似文献
126.
Functionalized Natural Particles: Light‐Induced Surface Modification of Natural Plant Microparticles: Toward Colloidal Science and Cellular Adhesion Applications (Adv. Funct. Mater. 18/2018)
下载免费PDF全文

127.
Nikki Edleman ;Yong-Siang Tan ;Tom Tillery ;Stephen Savas ;Andreas Kadavanich ;Allan Wiesnoski 《集成电路应用》2009,(1):34-36
对45nm及以下技术节点的逻辑器件嗣造来说,经过次数不断增加的高剂量离子注入光阻层的清洗步骤后,仍保持超浅结(USJ)的完整性非常重要。在PMOS区采用SiGe带来了材料方面的又—挑战。一种新型短循环法可精确测量各种去胶储洗工艺造成的非晶硅或SiGe的损失量。 相似文献
128.
Over-erase phenomenon in SONOS-type flash memory and its minimization using a hafnium oxide charge storage Layer 总被引:1,自引:0,他引:1
Yan-Ny Tan Chim W.-K. Byung Jin Cho Wee-Kiong Choi 《Electron Devices, IEEE Transactions on》2004,51(7):1143-1147
The over-erase phenomenon in the polysilicon-oxide-silicon nitride-oxide-silicon (SONOS) memory structure is minimized by using hafnium oxide or hafnium aluminum oxide to replace silicon nitride as the charge storage layer (the resulting structures are termed SOHOS devices, where the "H" denotes the high dielectric constant material instead of silicon nitride). Unlike SONOS devices, SOHOS structures show a reduced over-erase phenomenon and self-limiting charge storage behavior under both erase and program operations. These are attributed to the differences in band offset and the crystallinity of the charge storage layer. 相似文献
129.
AIM: To investigate the variation and biological properties of HPV16 E7 isolated from cervical cancer biopsy samples from highest incidence area in HuBei province of China. METHODS: HVP16 E7 sequences isolated from the cervical cancer biopsies of 10 local patients were amplified, sequenced and compared with prototype E7 gene. Then the variant gene was cloned into different vectors to study the antigenicity, expression and immunogenicity of its protein by Western blot, immunofluorescence and genetic immunization in vitro or in vivo. RESULTS: The results showed that 7 of 10 samples had the same mutations which led to a nonsense mutation at codon 43 of E7 sequence. The truncated E7 protein could be recognized by standard E7 monoclonal antibody in Western blot and expressed in NIH3T3 cells. In the blood sera of mice immunized intramuscularly by the plasmid DNA expressing the variant E7 gene specific E7 antibodies could be detected at week 2, 3, 5 and 6 after inoculation. However, no specific lymphoproliferation after E7 protein stimulation in vitro was detected by MTT colorimetric assay in comparison to the prototype E7 protein. CONCLUSION: HPV16 E7 gene may show variation in China and the variant protein could be expressed and induce host humoral immune response, but could not elicit special cellular-immune response against it. These data might hold the key for future development of HPV16 vaccine in HuBei province of China. 相似文献
130.