全文获取类型
收费全文 | 5129篇 |
免费 | 145篇 |
国内免费 | 39篇 |
专业分类
电工技术 | 93篇 |
综合类 | 5篇 |
化学工业 | 994篇 |
金属工艺 | 123篇 |
机械仪表 | 209篇 |
建筑科学 | 97篇 |
能源动力 | 193篇 |
轻工业 | 231篇 |
水利工程 | 27篇 |
石油天然气 | 5篇 |
无线电 | 906篇 |
一般工业技术 | 913篇 |
冶金工业 | 564篇 |
原子能技术 | 25篇 |
自动化技术 | 928篇 |
出版年
2024年 | 9篇 |
2023年 | 31篇 |
2022年 | 111篇 |
2021年 | 108篇 |
2020年 | 35篇 |
2019年 | 56篇 |
2018年 | 66篇 |
2017年 | 76篇 |
2016年 | 101篇 |
2015年 | 102篇 |
2014年 | 178篇 |
2013年 | 376篇 |
2012年 | 269篇 |
2011年 | 324篇 |
2010年 | 234篇 |
2009年 | 267篇 |
2008年 | 272篇 |
2007年 | 242篇 |
2006年 | 230篇 |
2005年 | 197篇 |
2004年 | 164篇 |
2003年 | 158篇 |
2002年 | 128篇 |
2001年 | 116篇 |
2000年 | 86篇 |
1999年 | 99篇 |
1998年 | 250篇 |
1997年 | 150篇 |
1996年 | 114篇 |
1995年 | 72篇 |
1994年 | 96篇 |
1993年 | 61篇 |
1992年 | 45篇 |
1991年 | 54篇 |
1990年 | 36篇 |
1989年 | 45篇 |
1988年 | 54篇 |
1987年 | 39篇 |
1986年 | 32篇 |
1985年 | 24篇 |
1984年 | 28篇 |
1983年 | 24篇 |
1982年 | 11篇 |
1981年 | 16篇 |
1980年 | 15篇 |
1979年 | 9篇 |
1978年 | 12篇 |
1977年 | 18篇 |
1976年 | 34篇 |
1974年 | 7篇 |
排序方式: 共有5313条查询结果,搜索用时 15 毫秒
181.
Commercial application scenario using patent analysis: Fermentative hydrogen production from biomass
Chiung-Wen Hsu Pao-Long Chang Chih-Min Hsiung Chiu-Yue Lin 《International Journal of Hydrogen Energy》2014
The main purpose of this study is to use patent analysis to investigate scenarios for future commercial applications of dark fermentation or anaerobic fermentation using biomass or organic matter as feedstock materials. The first step in this study includes a patent search procedure and patent content interpretation, in which 29 technology patents were identified from the US patent database and divided into five groups in accordance with the scope of their technical applications. The following five scenarios of commercial applications of biomass fermentation for hydrogen production were established through a combination of group applications: screening and cultivation of hydrogen-producing bacteria, biomass waste sources, biomass energization application, value enhancement of waste or wastewater treatment systems, and the application of a multi-functional hydrogen production system integrated with other technologies. 相似文献
182.
183.
Zhang Gang Hsu Ching-Hsien Robert Lai Huadong Zheng Xianghan 《Multimedia Tools and Applications》2018,77(8):9849-9869
Multimedia Tools and Applications - Automated annotation of skin biopsy histopathological images provides valuable information and supports for diagnosis, especially for the discrimination between... 相似文献
184.
The mechanical and adhesive properties of C60@(10,10) carbon nanopeapods (CNPs) adhering to gold surfaces are investigated by atomistic simulations. The effects of C60 fill density, tube length, surrounding temperature, and peeling velocity on the adhesion behavior are studied. Results show that the interfacial binding energy of CNPs (which depends on the C60 fill density and temperature) is 2.0∼4.4% higher than that of (10,10) single-walled CNTs and 3.4∼4.7% lower than that of (5,5)@(10,10) double-walled CNTs (DWCNTs). Despite their lower interfacial binding energy, CNPs have a higher adhesive strength than that of DWCNTs (1.53 nN vs. 1.4 nN). Distinct from the inner tubes of DWCNTs, which have continuum mechanical properties, the discrete C60 molecules that fill CNPs exhibit unique composite mechanical properties, with high flexibility and bend-buckling resistance. The bend-buckling forces for CNPs filled with a low/medium fill density of C60 are approximately constant. When the fill density is 1 C60 molecule per nanometer length, the bend-buckling force dramatically increases. 相似文献
185.
Yu‐Ta Chen Shau‐Wei Hsu Bao‐Jen Pong Mang Ou‐Yang Cheng‐Chung Lee 《Journal of the Society for Information Display》2013,21(6):231-238
This work presents an image displacement measurement by using a box pattern and the edge spread function analysis in the polarized based stereoscopic displays. The measurement determines to identify three factors (i.e., box size, image displacement, and spatial frequency response (SFR)) from the box patterns. The polarized based stereoscopic displays might sacrifice pixels for producing 3D images, which might produce errors in the image displacement and then affect the depth perception indirectly. Based on the measurement, the errors can be quantified by using the three factors. Owing to the light leakage distorting the edge spread function to obtain an inferior SFR, exactly how light leakage affects the edge spread function can be resolved on the basis of the SFR results, especially at a frequency (1/display pixel) of 1.9 in the case of the horizontal displacement. Light leakage also induces the error of the box height in even and odd intervals of the vertical displacements more than 2 pixels and 0.5 pixels, respectively. The image displacement measurement provides a simple and comprehensive means of evaluating the optical characteristics, disparity, and sharpness of the stereoscopic displays, via the three factors. 相似文献
186.
While previous research on polycaprolactone (PCL) and polyethylene glycol (PEG) triblock copolymers has focused on their use as hydrogels or with conventional scaffold fabrication methods, this work concentrates on producing viable photocurable resins from synthesized triblocks for use in a layer-by-layer 3D printer. After successful synthesis of PCL-PEG-PCL and PCL-PEG-PCL-diacrylate triblocks, they were combined with (hydroxyethyl)methacrylated polyethylene glycol (PEG-HEMA) and used as biomaterials in a dynamic masking 3D printing system to fabricate porous scaffolds. Diacrylation of the polymer (PCL-PEG-PCL-DA) revealed a substantial increase in mechanical strength and resulting compound resolved the re-dissolving issue significantly during the 3D printing process. Degradation tests were carried out by incubation in phosphate-buffered saline, and both biomaterials demonstrated their degradation resistance with steady pH levels and mass loss plateauing at 20% over a sixty day timeframe. Preliminary MG63 cell culture tests on the cross-linked 3D porous structures showed no significant cytotoxicity and MTT assay data verified cell proliferation on the photocured samples after three days. As a result, end-capping PCL-PEG-PCL with acrylates demonstrated advantages over PCL-PEG-PCL while keeping similar performance in degradation and biocompatibility. Overall results from this work demonstrate the suitability of the novel triblocks for use as biomaterials in tissue engineering scaffolds. 相似文献
187.
We plan the manpower supply for aircraft line maintenance, taking into account two types of stochastic incidents: manpower demands for a flight and the number of aircraft needing to be serviced at one time. The problem is solved to find the shift and maintenance group combinations best suited for the given airline. The optimal aircraft maintenance certification for a crew is also analyzed to improve the entire manpower structure. In addition, the addition of temporary manpower required for actual daily operations is also considered as a part of understanding the total manpower utilized in actual operations. An integrated method including scenario generation and a stochastic model is developed to deal with the problem. Finally, we perform a case study based on operating data obtained from a major airline in Taiwan. The results and findings are compared with the airline’s current manpower plan in the discussion, and suggestions for improvement are made. 相似文献
188.
Mengjiao Li Feng-Shou Yang Hung-Chang Hsu Wan-Hsin Chen Chia Nung Kuo Jiann-Yeu Chen Shao-Heng Yang Ting-Hsun Yang Che-Yi Lin Yi Chou Mu-Pai Lee Yuan-Ming Chang Yung-Cheng Yang Ko-Chun Lee Yi-Chia Chou Chen-Hsin Lien Chun-Liang Lin Ya-Ping Chiu Chin Shan Lue Shu-Ping Lin Yen-Fu Lin 《Advanced functional materials》2021,31(5):2007587
Defect engineering represents a significant approach for atomically thick 2D semiconductor material development to explore the unique material properties and functions. Doping-induced conversion of conductive polarity is particularly beneficial for optimizing the integration of layered electronics. Here, controllable doping behavior in palladium diselenide (PdSe2) transistor is demonstrated by manipulating its adatom-vacancy groups. The underlying mechanisms, which originate from reversible adsorption/desorption of oxygen clusters near selenide vacancy defects, are investigated systematically via their dynamic charge transfer characteristics and scanning tunneling microscope analysis. The modulated doping effect allows the PdSe2 transistor to emulate the essential characteristics of photo nociceptor on a device level, including firing signal threshold and sensitization. Interestingly, electrostatic gating, acting as a neuromodulator, can regulate the adaptive modes in nociceptor to improve its adaptability and perceptibility to handle different danger levels. An integrated artificial nociceptor array is also designed to execute unique image processing functions, which suggests a new perspective for extension of the promise of defect engineered 2D electronics in simplified sensory systems toward use in advanced humanoid robots and artificial visual sensors. 相似文献
189.
Epidural fibrosis, an inevitable part of the postoperative healing process, is one of the important causes of failed back surgery syndrome after spinal surgery. The aim of this study was to examine the inhibitory effect of a novel material 1,4-butanediol diglycidyl ether-cross-linked hyaluronan (cHA) on fibrosis in primary tenocytes. cHA inhibited migration, cell proliferation, and suppressed the expression of fibronectin, but not transforming growth factor-β, in primary tenocytes. cHA significantly increased matrix metalloproteinase-3 but decreased collagen-1 and microtubule-associated protein light chain 3-II expression in a dose-dependent manner compared with control groups. We therefore concluded that suppressing autophagy activity may be involved in the anti-fibrotic effect of cHA in primary tenocytes. Further, cHA may have the potential for preventing epidural fibrosis and subsequent failed back syndrome in patients with laminectomy in the future. 相似文献