首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   131篇
  免费   3篇
电工技术   1篇
化学工业   32篇
建筑科学   5篇
能源动力   2篇
轻工业   23篇
水利工程   18篇
无线电   15篇
一般工业技术   17篇
冶金工业   7篇
自动化技术   14篇
  2024年   1篇
  2023年   1篇
  2022年   4篇
  2021年   2篇
  2020年   9篇
  2019年   15篇
  2018年   5篇
  2017年   2篇
  2016年   5篇
  2014年   3篇
  2013年   15篇
  2012年   7篇
  2011年   11篇
  2010年   7篇
  2009年   9篇
  2008年   4篇
  2007年   4篇
  2006年   3篇
  2005年   2篇
  2003年   4篇
  2002年   3篇
  2000年   1篇
  1999年   3篇
  1998年   2篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1993年   2篇
  1991年   2篇
  1979年   1篇
  1977年   1篇
  1975年   2篇
排序方式: 共有134条查询结果,搜索用时 0 毫秒
21.
Methods for measuring the surface areas of powdered solids are considered and the specific surface areas of ferric oxide and alumina powders using adsorption of stearic acid from benzene solution are determined. It has been found that the value of the specific surface area of both powders agree with the BET nitrogen gas adsorption area if it is considered that the area occupied per molecule of stearic acid on the powder surface is of the order of 60–70Å2. This finding shows that orientation of the stearic acid molecule on the solid/liquid interface takes place so that stearic acid molecules lie neither completely perpendicular nor completely parallel to the surface. Possible orientations of stearic acid chains on the surface are envisaged.  相似文献   
22.
The aim of this study was to investigate the antioxidant and antimicrobial activity of chitosan, EDTA, eugenol and peppermint essential oil and their effect on color and oxidative stability of chicken noodles stored at 35 ± 2 °C. Results indicated that among the four preservatives, eugenol treatment exhibited higher ABTS+ (2-2-azinobis-3ethylbenthiazoline-6-sulphonic acid) radical cation activity (89.54%), DPPH (1, 1-diphenyl-2-picrylhydrazil) (51.30%) and superoxide anion scavenging activity (66.82%). Total polyphenol content was also higher in eugenol treated samples. The samples treated with eugenol and chitosan protect against an increase lightness (L-value) and decrease in redness (a) and yellowness (b) values during storage. However, pH value was highest in noodles with chitosan treatment while TBARS (2-thiobarbituric acid reacting substances) and FFA (Free fatty acids) contents were lowest in noodles with eugenol irrespective of storage periods. Eugenol treatment also showed positive impact on microbiological quality and sensory attributes. In conclusion, eugenol has more potential as a natural preservative to increase shelf-life of chicken noodles.  相似文献   
23.
Nepal, one of the least developed countries, is characterized by low per capita energy consumption and hugely dominated by traditional energy sources. Despite having enormous potential of hydro-electricity, only 50% of the total population has access to grid electricity. Firewood is the primary energy source for domestic purposes in rural environments. Due to geographical remoteness, a scattered consumer, higher costs of supply and maintenance, low consumption and low level of households’ income linking the rural areas to national electricity grid is difficult and implausible. In order to solve the energy problem in rural areas, Nepal’s government has initiated the production and distribution of several renewable energy technologies. Among several renewable technologies, micro-hydropower has been one of the most promising and widely adopted decentralized technologies to distribute electricity in rural areas. This article begins with a general overview of energy situation in Nepal. Present status and perspective of micro-hydro plants have also been discussed. Similarly, the dynamics of the relationship between electricity and socio-economic development has been analyzed by means of a typical rural electrification project in Tangting, Nepal by assessing the impacts of electricity on health, education, environment, and income in the village. The community has greatly benefitted from the arrival of environment friendly and affordable electricity. It has been concluded that the task of providing electricity to more remote and isolated villages is still challenging in Nepal. More systematic and comprehensive study supported by research and development is required to extend micro-hydro based electricity in more remote and poor communities of Nepal.  相似文献   
24.
We describe a complete noise analysis and application of a custom made AFM force spectroscopy setup on pulling a recombinant protein with an NRR domain of mouse Notch 1. Our table top AFM setup is affordable, has an open architecture, and is easily transferable to other laboratories. Its calculated noise characteristics are dominated by the Brownian noise with 2% non-Brownian components integrated over the first thermally induced resonance of a typical cantilever. For a typical SiN cantilever with a force constant of ~15 pN nm(-1) and in water the force sensitivity and resolution are less than 10 pN, and the corresponding deflection sensitivities are less than 100 pm Hz(-1/2). Also, we obtain a sub-ms time resolution in detecting the protein length change, and only few ms cantilever response times as measured in the force clamp mode on a well-known protein standard. Using this setup we investigate force-induced conformational transitions in the NRR region of a mouse Notch 1. Notch is an important protein related to leukemia and breast cancers in humans. We demonstrate that it is feasible to develop AFM-based studies of the force-induced conformational transitions in Notch. Our results match recent steered molecular dynamics simulations of the NRR unfolding and constitute a first step towards a detailed study of Notch activation with AFM.  相似文献   
25.
In this study, the qualities of the final effluents from nine different industries (A, B, C, D, E, F, G, H and I) discharging 1,4‐dioxane mainly as effluents were assessed using sulphur‐oxidising bacteria (SOB) as a test micro‐organism in batch mode. Results showed that effluent from industry ‘B’ was the most toxic of all the effluents tested, followed by E, C and A effluents. An EC50 value of 13% was obtained for effluent from B, whereas with E, C and A effluents, the EC50 values of 23%, 25% and 29% were found, respectively. Similarly, batch tests were performed in order to evaluate the potential for 1,4‐dioxane to inhibit growth on SOB. The lowest test concentration of 1,4‐dioxane (12 μg/L) resulted in 17% of inhibition of SOB, whereas the highest test concentration (3.125 mg/L) resulted in > 75% of the inhibition. An EC50 value of 0.105 mg/L was obtained for 1,4‐dioxane.  相似文献   
26.
Life cycle costs of a new steel portal frame building system incorporating energy efficient sandwich panels are compared with those of a conventional steel portal frame building system for use in industrial and commercial buildings. The economic benefits of the new building system have been demonstrated through cost assessment of energy in use. The results from life cycle cost analysis of both the new and conventional portal frame building systems indicate that, despite slightly higher initial costs, the new building system costs significantly less than the conventional system over its complete life cycle of 50 years. The new system provides improved economic performance along with a more energy-efficient model for commercial/industrial building design in the Australian climate. Le coût du cycle de vie d'un nouveau système de bâtiment à portique en acier comportant des panneaux en sandwich efficaces au plan énergétique est comparé à un système classique pour un emploi dans des bâtiments industriels et commerciaux. Les avantages économiques du nouveau système ont été démontrés par une évaluation des dépenses énergétiques. Il ressort de l'analyse comparative du coût du cycle de vie du nouveau et de l'ancien système qu'en dépit d'une légère augmentation du coût de départ, le nouveau système est nettement moins onéreux que l'ancien sur un cycle de vie complet de 50 ans. Les performances économiques du nouveau système sont supérieures à celles du système classique, avec de meilleures performances énergétiques pour la conception de bâtiments commerciaux et industriels sous le climat australien.  相似文献   
27.
This paper explores the similarities and differences between bicycle and motorcycle crashes with other motor vehicles. If similar treatments can be effective for both bicycle and motorcycle crashes, then greater benefits in terms of crash costs saved may be possible for the same investment in treatments. To reduce the biases associated with under-reporting of these crashes to police, property damage and minor injury crashes were excluded. The most common crash type for both bicycles (31.1%) and motorcycles (24.5%) was intersection from adjacent approaches. Drivers of other vehicles were coded most at fault in the majority of two-unit bicycle (57.0%) and motorcycle crashes (62.7%). The crash types, patterns of fault and factors affecting fault were generally similar for bicycle and motorcycle crashes. This confirms the need to combat the factors contributing to failure of other drivers to yield right of way to two-wheelers, and suggest that some of these actions should prove beneficial to the safety of both motorized and non-motorized two-wheelers. In contrast, child bicyclists were more often at fault, particularly in crashes involving a vehicle leaving the driveway or footpath. The greater reporting of violations by riders and drivers in motorcycle crashes also deserves further investigation.  相似文献   
28.
Subsurface Characterization Using Artificial Neural Network and GIS   总被引:2,自引:0,他引:2  
A method for characterizing the subsurface is developed using an artificial neural network (ANN) and geographic information system (GIS). Data on the distribution of aquifer materials from monitoring well lithologic logs are used to train a multilayer perceptron using the back-propagation algorithm. The trained ANN predicts using an appropriate prediction scale, the subsurface formation materials at each point on a discretized grid of the model area. GIS is then used to develop subsurface profiles from the data generated using the ANN. These subsurface profiles are then compared with available geological sections to check the accuracy of the ANN-GIS generated profiles. This methodology is applied to determine the aquifer extent and calculate aquifer parameters for input to ground-water models for the multiaquifer system underlying the city of Bangkok, Thailand. A selected portion of the model domain is used for illustration. The integrated approach of ANN and GIS is shown to be a powerful tool for characterizing complex aquifer geometry, and for calculating aquifer parameters for ground-water flow modeling.  相似文献   
29.
Electrolytic conductivities of potassium halides, KX (X = Cl, Br, I) have been investigated in 10, 20, and 30 mass% glycerol + H2O mixtures at 298.0, 308.0, and 318.0 K. The conductance data have been analyzed by the Fuoss-conductance–concentration equation in terms of the limiting molar conductance (Λ0), the association constant (K A ), and the distance of closest approach of ion (R). The association constant (K A ) tends to increase in the order: 10 mass% < 20 mass% < 30 mass% glycerol + water mixtures, while it decreases with temperature. Thermodynamic parameters ΔH 0, ΔG 0, and ΔS 0 are obtained and discussed. Also, Walden products (Λ0η) are reported. The results have been interpreted in terms of ion–solvent interactions and structural changes in the mixed solvents.  相似文献   
30.
Water Resources Management - Diversified water supply schemes can reduce both peak demand and overall demand in the urban water supply network. Consequently, they provide benefits to both the water...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号