全文获取类型
收费全文 | 2075篇 |
免费 | 77篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 11篇 |
综合类 | 6篇 |
化学工业 | 421篇 |
金属工艺 | 39篇 |
机械仪表 | 28篇 |
建筑科学 | 101篇 |
矿业工程 | 8篇 |
能源动力 | 29篇 |
轻工业 | 202篇 |
水利工程 | 11篇 |
石油天然气 | 4篇 |
无线电 | 209篇 |
一般工业技术 | 312篇 |
冶金工业 | 401篇 |
原子能技术 | 10篇 |
自动化技术 | 362篇 |
出版年
2023年 | 13篇 |
2022年 | 18篇 |
2021年 | 51篇 |
2020年 | 31篇 |
2019年 | 34篇 |
2018年 | 40篇 |
2017年 | 43篇 |
2016年 | 52篇 |
2015年 | 41篇 |
2014年 | 43篇 |
2013年 | 103篇 |
2012年 | 101篇 |
2011年 | 128篇 |
2010年 | 95篇 |
2009年 | 100篇 |
2008年 | 100篇 |
2007年 | 97篇 |
2006年 | 95篇 |
2005年 | 61篇 |
2004年 | 55篇 |
2003年 | 52篇 |
2002年 | 65篇 |
2001年 | 48篇 |
2000年 | 41篇 |
1999年 | 46篇 |
1998年 | 105篇 |
1997年 | 73篇 |
1996年 | 57篇 |
1995年 | 41篇 |
1994年 | 25篇 |
1993年 | 34篇 |
1992年 | 15篇 |
1991年 | 15篇 |
1990年 | 21篇 |
1989年 | 18篇 |
1988年 | 16篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 13篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1977年 | 17篇 |
1976年 | 18篇 |
1975年 | 7篇 |
1966年 | 7篇 |
排序方式: 共有2154条查询结果,搜索用时 484 毫秒
31.
Michael Gelfer Carlos Avila‐orta Lizhi Liu Ling Yang Benjamin Chu Benjamin S. Hsiao Hyun H. Song Mayu Si Miriam Rafailovich Andy H. Tsou 《Polymer Engineering and Science》2002,42(9):1841-1851
A series of nanocomposites prepared by melt‐blending of cloisite‐based organoclays with poly(ethylene‐vinylacetate) (EVA) and neutralized poly (ethylene‐methacrylic acid) (EMA) copolymers were investigated via DSC, small‐angle X‐ray scattering (SAXS), and rheological techniques. SAXS results indicated partial clay exfoliation in all samples. In both EMA and EVA systems, the nominal melting temperature Tm and bulk crystallinity are not significantly affected by the presence of organoclays, suggesting that clay particles are predominantly confined in the amorphous phase. In rheological measurements (above Tm), the EVA‐clay system demonstrated a solid‐like rheological behavior under the small‐strain oscillatory shear, yet it was able to yield and flow under a steady shear, which is the characteristic of physical crosslinking. In contrast, the EMA‐clay system exhibited a melt‐like rheological behavior, where the influence of organoclay on the thermorheological behavior of the EMA composite was quite minimal. We propose that the carbonyl groups of vinylacetate in EVA interact with the clay surface, resulting in a strong physically crosslinking like interaction in the melt. On the other hand, the interaction between EMA and clay is weak because of repulsion between carboxyl anions and negatively charged clay surface. 相似文献
32.
Sebastian T. Vogel 《Ethik in der Medizin》2009,19(2):323-324
Fall und Kommentare
Gibt es eine Pflicht zum pr?natalen Nichtwissen? 相似文献33.
Microstructure and texture evolution during warm compression of the magnesium alloy AZ31 总被引:1,自引:0,他引:1
The evolution of the microstructure and texture with strain during compression at 150℃ of the magnesium alloy AZ31 has been investigated using the electron backscattered diffraction (EBSD) technique. The initial samples were chosen to have a strong basal plane texture with the crystal c-axes perpendicular to the compression direction. The EBSD data provide evidence concerning the relative activity of both {10-12} extension twinning and slip, and suggest that non-basal slip is important in samples deformed to a strain of more than 0.2. The relative contributions of the twinning and the slip during deformation have been discussed based on the results above. 相似文献
34.
E. Vogel K. Dobbert K. Meissner U. Ruh E. Bich 《International Journal of Thermophysics》1991,12(3):469-490
The paper reports experimental results for the viscosity of the vapor mixtures methanol-benzene (five mole fractions with densities up to 1.5kg·m–3 and 0.022 mol·L
–1) and methanol-cyclohexane (four mole fractions with densities up to 1.9kg·m–3 and 0.026 mol·L
–1). In analogy to the pure components, the measurements on the mixtures were carried out with an oscillating-disk viscometer with small gaps, completely made of quartz, beginning as near as possible to room temperature and continuing to a maximum temperature of 630 K. A first evaluation by means of the Chapman-Enskog theory of dilute gases has shown differences in the resulting values of the interaction viscosity
ij
(0) in the limit of zero density exceeding the experimental errors. Consistent results were obtained by taking into account the initial density dependence of the viscosity within the framework of the modified Enskog theory for gaseous mixtures. The values of
ij
(0) were also used to estimate binary diffusion coefficients of the mixtures. 相似文献
35.
Lucian L. Visinescu Olajumoke Azogu Sherry D. Ryan Yu “Andy” Wu 《International journal of human-computer interaction》2016,32(11):885-900
Since the use of network-based storage as a cloud computing service [Storage as a Service (StaaS)] becomes ubiquitous, users who store data in the cloud are exposed to risk and potentially severe consequences. Therefore, individuals should carefully consider security and privacy issues when using StaaS. Drawing upon the principle of self-preservation and the theory of protection motivation, this study develops a research model explaining the mechanisms leading to the development of a protection strategy for individuals’ safe use of StaaS and empirically tests the proposed model. The results show that the natural propensity to trust, an individual trait, influences an individual’s need for privacy. This, in turn, along with perception of privacy risk, significantly affects individuals’ perception of the need to protect themselves. Three coping appraisal factors, preventive measures, self-efficacy, and willingness to incur cost of prevention, together with the individual perceived need to protect self, directly and positively affect users’ need to develop a protection strategy in a cloud computing environment. Theoretical and practical implications are discussed. 相似文献
36.
37.
Andy Jiang 《计算机网络世界》2009,(11):47-47
2009年度第12期IT品牌评选活动得到众多热心读者的踊跃参与,包括全国各地的业界专家、设计院、系统集成商以及用户等专业人士。此次评选活动,共收到读者们的评选意见回馈表1026份,根据品牌认知、成功案例、价格定位、质量维护、服务支持等多项指标,评选出了十大IT品牌包括综合布线十大产品品牌,以及本次新增加的布线新锐品牌。 相似文献
38.
Experimental viscosity data of ethane, carbon dioxide, and three mole fractions of the binary system carbon dioxide + ethane in the temperature range 293.15<T633.15 K and in the density range 0.010.05 mol·L–1 reported earlier were evaluated simultaneously to find out a useful correlation and extrapolation scheme for the viscosity of binary systems in the range of moderate densities. A procedure based on the ideas of the modified Enskog theory has been found to give the best results. Dependent on temperature, the collision diameters related to the equilibrium radial distribution function at contact are fitted to viscosity values of the pure substances and of at least one mixture. The results are compared with experimental data from the literature. A recommendation is given concerning the density range in which the first density contribution to the viscosity coefficient of the system carbon dioxide + ethane is sufficient to be included.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A. 相似文献
39.
Andy Shar Phillip Glass Sung Hyun Park Daeha Joung 《Advanced functional materials》2023,33(5):2211079
3D printing of conductive elastomers is a promising route to personalized health monitoring applications due to its flexibility and biocompatibility. Here, a one-part, highly conductive, flexible, stretchable, 3D printable carbon nanotube (CNT)-silicone composite is developed and thoroughly characterized. The one-part nature of the inks: i) enables printing without prior mixing and cures under ambient conditions; ii) allows direct dispensing at ≈100 µm resolution printability on nonpolar and polar substrates; iii) forms both self-supporting and high-aspect-ratio structures, key aspects in additive biomanufacturing that eliminate the need for sacrificial layers; and iv) lends efficient, reproducible, and highly sensitive responses to various tensile and compressive stimuli. The high electrical and thermal conductivity of the CNT-silicone composite is further extended to facilitate use as a flexible and stretchable heating element, with applications in body temperature regulation, water distillation, and dual temperature sensing and Joule heating. Overall, the facile fabrication of this composite points to excellent synergy with direct ink writing and can be used to prepare patient-specific wearable electronics for motion detection and cardiac and respiratory monitoring devices and toward advanced personal health tracking and bionic skin applications. 相似文献
40.
Electrophysiological evidence for a postperceptual locus of suppression during the attentional blink 总被引:1,自引:0,他引:1
When an observer detects a target in a rapid stream of visual stimuli, there is a brief period of time during which the detection of subsequent targets is impaired. In this study, event-related potentials (ERPs) were recorded from normal adult observers to determine whether this "attentional blink" reflects a suppression of perceptual processes or an impairment in postperceptual processes. No suppression was observed during the attentional blink interval for ERP components corresponding to sensory processing (the P1 and N1 components) or semantic analysis (the N400 component). However, complete suppression was observed for an ERP component that has been hypothesized to reflect the updating of working memory (the P3 component). Results indicate that the attentional blink reflects an impairment in a postperceptual stage of processing. 相似文献