全文获取类型
收费全文 | 1834篇 |
免费 | 167篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 29篇 |
技术理论 | 1篇 |
综合类 | 5篇 |
化学工业 | 403篇 |
金属工艺 | 22篇 |
机械仪表 | 32篇 |
建筑科学 | 44篇 |
能源动力 | 54篇 |
轻工业 | 89篇 |
水利工程 | 6篇 |
石油天然气 | 1篇 |
无线电 | 404篇 |
一般工业技术 | 480篇 |
冶金工业 | 133篇 |
原子能技术 | 9篇 |
自动化技术 | 296篇 |
出版年
2023年 | 7篇 |
2022年 | 20篇 |
2021年 | 34篇 |
2020年 | 22篇 |
2019年 | 39篇 |
2018年 | 41篇 |
2017年 | 38篇 |
2016年 | 68篇 |
2015年 | 73篇 |
2014年 | 75篇 |
2013年 | 197篇 |
2012年 | 101篇 |
2011年 | 100篇 |
2010年 | 99篇 |
2009年 | 101篇 |
2008年 | 89篇 |
2007年 | 101篇 |
2006年 | 81篇 |
2005年 | 77篇 |
2004年 | 60篇 |
2003年 | 51篇 |
2002年 | 39篇 |
2001年 | 37篇 |
2000年 | 34篇 |
1999年 | 25篇 |
1998年 | 58篇 |
1997年 | 39篇 |
1996年 | 41篇 |
1995年 | 37篇 |
1994年 | 29篇 |
1993年 | 24篇 |
1992年 | 16篇 |
1991年 | 18篇 |
1990年 | 10篇 |
1989年 | 18篇 |
1988年 | 7篇 |
1987年 | 11篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1984年 | 13篇 |
1983年 | 5篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 2篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1973年 | 5篇 |
排序方式: 共有2008条查询结果,搜索用时 0 毫秒
991.
Keng-Ming Chen Li-Huei Lin Min-Yan Dong Chien Fu Wang Mou-Chuan Hwang 《Journal of surfactants and detergents》2010,13(4):417-422
A family of phosphated alkyl oligoglucoside surfactants was prepared by reacting alkyl oligoglucosides with phosphorus oxychloride.
The alkyl oligoglucosides were obtained by an usual method in which the glucose is reacted with a fatty alcohol containing
10–18 carbon atoms. These novel phosphated surfactants have been found to exhibit good surface tension, foaming and wetting
power. The critical micelle concentration was found to increase with the length of hydrocarbon chain of the surfactant. The
surface excess concentration and the interfacial area per surfactant molecule are reported. These phosphated surfactants also
exhibit a good performance to improve the whiteness and wetting of cotton fabrics in a hydrogen oxide bleaching system, and
they are also found to be more biodegradable than conventional surfactants. 相似文献
992.
Sheng‐Yen Wu Siu‐Ming Yuen Chen‐Chi M. Ma Chin‐Lung Chiang Yuan‐Li Huang Hsin‐Ho Wu Chih‐Chun Teng Cheng‐Chien Yang Ming‐Hsiung Wei 《应用聚合物科学杂志》2010,115(6):3481-3488
Both epoxy resin and acid‐modified multiwall carbon nanotube (MWCNT) were treated with 3‐isocyanatopropyltriethoxysilane (IPTES). Scanning electron microscopy (SEM) and transmission electronic microscope (TEM) images of the MWCNT/epoxy composites have been investigated. Tensile strength of cured silane‐modified MWCNT (1.0 wt %)/epoxy composites increased 41% comparing to the neat epoxy. Young's modulus of cured silane‐modified MWCNT (0.8 wt %)/epoxy composites increased 52%. Flexural strength of cured silane‐modified MWCNT (1.0 wt %)/epoxy composites increased 145% comparing to neat epoxy. Flexural modulus of cured silane‐modified MWCNT (0.8 wt %)/epoxy composites increased 31%. Surface and volume electrical resistance of MWCNT/epoxy composites were decreased with IPTES‐MWCNT content by 2 orders and 6 orders of magnitude, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
993.
Jia Peng Zheng Ruth Wei Li Peng Ren Yi Yang Chien Chun Shao Jun Cheng Wang Ching Long Lin Yu Hua Cheng Yang Yuan Wang 《Analog Integrated Circuits and Signal Processing》2010,65(1):115-121
In this paper, a novel design of spread-spectrum clock generator (SSCG) with a third-order error-feedback delta-sigma modulator
is presented. The proposed SSCG with triangular modulation can generate clocks with center spread ratios of 0.25, 1, 1.75,
2.5, 3.5, 5% and down spread ratios of 0.5, 2, 3.5, 5, 7, 10% over a wide frequency range from 20 to 700 MHz. The SSCG is
implemented on a chip using SMIC 0.13 um CMOS process. Our tests show that 11.31 dB attenuation of the EMI at 80 MHz with
down spread ratio of 10% and 12.98 dB attenuation at 133.3 MHz with center spread ratio of 5% can be achieved which is in
agreement with the theoretic calculation. 相似文献
994.
讨论了栅氧化层击穿的统计模型,并对业界广泛应用的1/E模型、E模型以及幂指数模型中栅氧化层击穿的物理机理进行了仔细研究,指出了各个模型应用的局限性,结合实验数据分析,明确给出了各个模型的应用范围。详细讨论了电场加速因子与激活能在三个模型中的不同物理含义,总结了电场加速因子、激活能随着栅氧化层厚度变化的发展趋势以及所对应的击穿机理,据此提出了通过激活能与电场加速因子选择和验证所用加速模型是否合理的方法。此方法为判断测试条件是否合理,分析测试结果的内在含义提供了更直接、有用的参考信息。 相似文献
995.
996.
Ran-Zan Wang Yin-Fang Chien Yung-Yi Lin 《Journal of Visual Communication and Image Representation》2010,21(7):751-761
Image sharing addresses a fault-tolerant protection mechanism for important images. In a typical image sharing scheme, the generated shadow images usually have a noise-like appearance that conceals the secret image completely, but this makes them difficult to identify and manage. This paper proposes a scalable user-friendly image sharing scheme in which each generated shadow image looks like a shrunken replica of the original image. The scheme provides an easy-to-identify interface for managing the shadow images. Compared with previous user-friendly image sharing schemes, the proposed method can reconstruct the original image without any loss and still has the small-size shadow images. A notable feature is that the qualities of generated shadow images are scalable in the proposed scheme, which allows the quality of the shadow images to be adjusted according to the requirements of diverse applications. 相似文献
997.
Po‐Chun Wang Gwo‐Long Li Shu‐Fen Huang Mei‐Juan Chen Shih‐Chien Lin 《ETRI Journal》2010,32(4):577-587
The layered coding structure of scalable video coding (SVC) with adaptive inter‐layer prediction causes noticeable computational complexity increments when compared to existing video coding standards. To lighten the computational complexity of SVC, we present a fast algorithm to speed up the inter‐mode decision process. The proposed algorithm terminates inter‐mode decision early in the enhancement layers by estimating the rate‐distortion (RD) cost from the macroblocks of the base layer and the enhancement layer in temporal, spatial, and inter‐layer directions. Moreover, a search range decision algorithm is also proposed in this paper to further increase the motion estimation speed by using the motion vector information from temporal, spatial, or inter‐layer domains. Simulation results show that the proposed algorithm can determine the best mode and provide more efficient total coding time saving with very slight RD performance degradation for spatial and quality scalabilities. 相似文献
998.
Chian‐Hui Lai Chia‐Yi Lin Huan‐Ting Wu Hau‐Shien Chan Yung‐Jen Chuang Chien‐Tien Chen Chun‐Cheng Lin 《Advanced functional materials》2010,20(22):3948-3958
The fluorescent dye Cy3 and galactose derivatives are covalently assembled with different ratios on the surfaces of magnetic nanoparticles (MNPs) to produce multifunctional HepG2 cancer cell–targeting agents and the effect of ligand spatial orientation on the MNP surface is investigated on targeting specificity. By using a mixture of bis‐N‐hydroxysuccinimide ester (a bifunctional linker) and OSu‐activated Cy3 (w/w = 30:1), stable and quantifiable fluorescent MNPs (Cy3@MNPs) are synthesized that could be subsequently loaded with galactosyl ligands. A mono‐antennary and two different tri‐antennary galactosyl ligands are individually immobilized on Cy3@MNPs, and the uptake efficiencies of the resulting galactosyl Cy3@MNPs by HepG2 and HeLa cells are investigated using confocal microscopy. The confocal images show that galactosyl Cy3@MNPs are sprayed over cytoplasm of the HepG2 cells, indicating that the MNP uptake occurs via receptor‐mediated endocytosis that is followed by release from endosomes. The results also reveal that the ligand spatial orientation affects the efficiency of the receptor‐mediated endocytosis and one of the tri‐antennary galactosyl ligands shows the best uptake efficiency owing to the optimal spatial presentation of the galactosyl moieties. Overall, it is shown that the MNP is a good ligand carrier and that, when pre‐assembled, the multivalent ligand structure enhances the interactions between the surface ligands of the MNPs and receptors of HepG2 cells. Additionally, the galactosyl Cy3@MNPs are not cytotoxic, indicating that they may potentially be used for in vivo applications. 相似文献
999.
Chang HM Liao YW Chiang CH Chen YJ Lai YH Chang YL Chen HL Jeng SY Hsieh JH Peng CH Li HY Chien Y Chen SY Chen LK Huo TI 《International journal of molecular sciences》2012,13(3):3598-3617
The only curative treatment for hepatic failure is liver transplantation. Unfortunately, this treatment has several major limitations, as for example donor organ shortage. A previous report demonstrated that transplantation of induced pluripotent stem cells without reprogramming factor c-Myc (3-genes iPSCs) attenuates thioacetamide-induced hepatic failure with minimal incidence of tumorigenicity. In this study, we investigated whether 3-genes iPSC transplantation is capable of rescuing carbon tetrachloride (CCl(4))-induced fulminant hepatic failure and hepatic encephalopathy in mice. Firstly, we demonstrated that 3-genes iPSCs possess the capacity to differentiate into hepatocyte-like cells (iPSC-Heps) that exhibit biological functions and express various hepatic specific markers. 3-genes iPSCs also exhibited several antioxidant enzymes that prevented CCl(4)-induced reactive oxygen species production and cell death. Intraperitoneal transplantation of either 3-genes iPSCs or 3-genes iPSC-Heps significantly reduced hepatic necrotic areas, improved hepatic functions, and survival rate in CCl(4)-treated mice. CCl(4)-induced hepatic encephalopathy was also improved by 3-genes iPSC transplantation. Hoechst staining confirmed the successful engraftment of both 3-genes iPSCs and 3-genes iPSC-Heps, indicating the homing properties of these cells. The most pronounced hepatoprotective effect of iPSCs appeared to originate from the highest antioxidant activity of 3-gene iPSCs among all transplanted cells. In summary, our findings demonstrated that 3-genes iPSCs serve as an available cell source for the treatment of an experimental model of acute liver diseases. 相似文献
1000.
Wei‐Ting Chien Chien‐Fu Liang Ching‐Ching Yu Jian‐ Hong Lin Haung‐Ting Wu Chun‐Cheng Lin 《Advanced Synthesis \u0026amp; Catalysis》2012,354(1):123-132
In this study, we describe the direct synthesis of uridine 5′‐diphosphate galactose (UDP‐Gal) by a wild‐type bacterial thymidylyltransferase (RmlA), which is used to synthesize thymidine 5′‐diphosphate glucose (TDP‐glucose) in nature. By using magnesium (Mg2+) as a cofactor and a reaction temperature of 55 °C, a one hundred milligram‐scale synthesis of UDP‐Gal was achieved by RmlA. In addition, RmlA was site‐specifically and covalently immobilized on magnetic nanoparticles (MNPa) The resulting RmlA‐MNP complex retained almost 95% of its activity after reuse in ten consecutive enzyme assays. Furthermore, β‐1,4‐galactosyltransferase (GalT) from Neisseria meningitides was successfully overexpressed and purified by using an intein‐mediated protein expression system. GalT was relatively stable at 25 °C, and its activity was enhanced in the presence of DTT and BSA. Thus, it was feasible to synthesize N‐acetyllactosamine (LacNAc) using RmlA and GalT in a sequential addition of enzyme and adjustment of thereaction temperature. These results demonstrate the potential applications of bacterial RmlA in carbohydrate synthesis. 相似文献