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   91篇
  免费   2篇
化学工业   14篇
机械仪表   3篇
建筑科学   1篇
能源动力   3篇
轻工业   17篇
无线电   10篇
一般工业技术   25篇
冶金工业   5篇
自动化技术   15篇
  2023年   1篇
  2022年   4篇
  2021年   5篇
  2020年   6篇
  2019年   8篇
  2018年   3篇
  2017年   3篇
  2016年   5篇
  2015年   2篇
  2014年   6篇
  2013年   4篇
  2012年   5篇
  2011年   1篇
  2010年   2篇
  2009年   6篇
  2008年   3篇
  2007年   6篇
  2006年   1篇
  2005年   4篇
  2004年   1篇
  2002年   2篇
  2001年   1篇
  2000年   2篇
  1997年   1篇
  1996年   2篇
  1995年   1篇
  1993年   1篇
  1991年   1篇
  1989年   1篇
  1988年   1篇
  1978年   1篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
排序方式: 共有93条查询结果,搜索用时 0 毫秒
21.
Aflatoxin M1 (AFM1) is a metabolite of aflatoxin B1 (AFB1) and secreted in milk of animals that are kept on a moldy diet. AFB1 is produced by several toxigenic species of fungi. In this study, the comparative efficacy of two mycotoxin binders was evaluated in terms of reducing excretion of AFM1, total viable bacterial count and somatic cell count in milk obtained from goats fed with AFB1 contaminated diet. A total of 32 lactating Beetal goats were reared and divided into 4 equal groups: Animals of group A were kept as control, while those in groups B, C, and D were individually fed with AFB1 at 40 µg alone, 40 µg AFB1 along with mycotoxin binder Toxfin® at 3 g kg?1 of cotton seed cake, and 40 µg AFB1 along with mycotoxin binder Elitox® at a dose rate of 1 g kg?1 of cotton seed cake, respectively. Toxfin® significantly decreased the excretion of AFM1 in goats’ milk by 49.57 % while Elitox® non-significantly reduced the excretion of AFM1 in goats’ milk by 19.49 %. Total viable bacterial count in milk samples of group C and D, and somatic cell count in milk samples of group C did not reduce significantly. However, somatic cell count in milk samples of group D reduced significantly. We conclude that the addition of Toxfin® in the moldy diet significantly reduce the excretion of AFM1 in animals’ milk and minimize the risk of mycotoxin toxicity to public health.  相似文献   
22.
It is necessary to develop solar grade (SoG) silicon for the photovoltaic industry. A desirable approach is to upgrade metallurgical grade (MG) silicon. The most problematic impurities to remove from MG silicon are B and P. A simple process to remove B from MG silicon has been developed by refining MG silicon in the molten state followed by directional solidification. With this approach, B has been reduced to 0.3 ppma, P to <10 ppma and all other impurities to <0.1 ppma using commercially available, as-received MG silicon. It remains to develop a similar P reduction process so that SoG silicon production from MG silicon can be commercialized. The B-removal process was applied to B overdoped electronic grade silicon, and the resulting material was used for crystal growth. Test solar cells of 12.5–13.4% (1 cm2) efficiency were produced.  相似文献   
23.
The influence of irradiation of minimally processed cabbage and cucumber on microbial safety, texture, and sensory quality was investigated. Minimally processed, polyethylene-packed, and irradiated cabbage and cucumber were stored at refrigeration temperature (5 degrees C) for 2 weeks. The firmness values ranged from 3.23 kg (control) to 2.82 kg (3.0-kGy irradiated samples) for cucumbers, with a gradual decrease in firmness with increasing radiation dose (0 to 3 kGy). Cucumbers softened just after irradiation with a dose of 3.0 kGy and after 14 days storage, whereas the texture remained within acceptable limits up to a radiation dose of 2.5 kGy. The radiation treatment had no effect on the appearance scores of cabbage; however, scores decreased from 7.0 to 6.7 during storage. The appearance and flavor scores of cucumbers decreased with increasing radiation dose, and overall acceptability was better after radiation doses of 2.5 and 3.0 kGy. The aerobic plate counts per gram for cabbage increased from 3 to 5 log CFU (control), from 1.85 to 2.93 log CFU (2.5 kGy), and from a few colonies to 2.6 log CFU (3.0 kGy) after 14 days of storage at 5 degrees C. A similar trend was noted for cucumber samples. No coliform bacteria were detected at radiation doses greater than 2.0 kGy in either cabbage or cucumber samples. Total fungal counts per gram of sample were within acceptable limits for cucumbers irradiated at 3.0 kGy, and for cabbage no fungi were detected after 2.0-kGy irradiation. The D-values for Escherichia coli in cucumber and cabbage were 0.19 and 0.17 kGy, and those for Salmonella Paratyphi A were 0.25 and 0.29 kGy for cucumber and cabbage, respectively.  相似文献   
24.
25.
Ceramic samples of Ba2 NaNb5O15, with the cations selectively substituted by Gd or Cr, showed that the changes in their orthorhombic lattice parametersa, b, andc were linearly correlated to each other. The changes in lattice parameters in thea, b, andc directions occurred proportionally in the ratio of 2.53.271.0.  相似文献   
26.
This paper considers a challenging problem: to simultaneously optimize the cost and the quality of service in opaque wavelength division multiplexing (WDM) networks. An optimization problem is proposed that takes the information including network topology, traffic between end nodes, and the target level of congestion at each link/node in WDM networks. The outputs of this problem include routing, link channel capacities, and the optimum number of switch ports locally added/dropped at all switch nodes. The total network cost is reduced to maintain a minimum congestion level on all links, which provides an efficient trade-off solution for the network design problem. The optimal information is utilized for dynamic traffic in WDM networks, which is shown to achieve the desired performance with the guaranteed quality of service in different networks. It was found that for an average link blocking probability equal to 0.015, the proposed model achieves a net channel gain in terms of wavelength channels ( ) equal to 35.72 , 39.09 , and 36.93 compared to shortest path first routing and equal to 29.41 , 37.35 , and 27.47 compared to alternate routing in three different networks.  相似文献   
27.
28.
This study was conducted to evaluate the presence, origination and classification of various hydrolyzing enzymes from malt and their specified hydrolyzing effects on various substrates for bioethanol production and to link these characteristics with the future prospects of bioethanol production. These enzymes are categorized as cell wall, starch, protein, lipid, polyphenol and thiol hydrolyzing enzymes based on their substrate specificity. Waste from beer fermentation broth (WBFB) has been evaluated as a rich source of malt derived hydrolyzing enzymes with significant self potential for bioethanol production. However, yeast cells cannot survive at the high temperature required for the saccharification activities of hydrolyzing enzymes during simultaneous saccharification and fermentation (SSF). This dilemma might be resolved by bioethanol production at elevated temperatures via cell-free fermentation systems in the presence of malt hydrolyzing enzymes. Moreover, emerging technologies such as genetic engineering in biomass and biotransformation in cell-free enzymatic systems will likely hasten bioethanol production in the near future. The present study adds new dimensions to eco-friendly bioethanol production from renewable and waste energy resources based on the specific hydrolyzing activities of malt enzymes.  相似文献   
29.
A systematic substitution of strontium ions by barium and/or calcium ions in the 21-structure ternary oxide La1.85Sr0.15CuO4–y , considered as the host system in this study, was carried out to produce four- and five-component metal oxides of the type La1.85(Sr0.15–x R x ) CuO4–y , where R=Ba and/or Ca and x<0.15. A series of samples was prepared using an oxalate coprecipitation procedure where high-purity starting materials, usually required in solid-state pyrolysis reactions, were not required. The experimental conditions for co-precipitation, annealing and pulverization processes were optimized. The X-ray powder diffraction patterns were used to indicate when the materials would become superconducting after annealing. The transition temperatures, T c, were measured from resistance versus temperature data which confirm that strontium is the best alkaline-earth metal among calcium, barium and strontium. Substitution or partial doping of strontium by calcium and/or barium in the host system decreased the T c of these ceramics. SEM measurements were carried out to determine the grain size of these materials and characteristic electron paramagnetic resonance spectra for these materials at different temperatures are reported.  相似文献   
30.
Web content filtering is one among many techniques to limit the exposure of selective content on the Internet. It has gotten trivial with time, yet filtering of multilingual web content is still a difficult task, especially while considering big data landscape. The enormity of data increases the challenge of developing an effective content filtering system that can work in real time. There are several systems which can filter the URLs based on artificial intelligence techniques to identify the site with objectionable content. Most of these systems classify the URLs only in the English language. These systems either fail to respond when multilingual URLs are processed, or over-blocking is experienced. This paper introduces a filtering system that can classify multilingual URLs based on predefined criteria for URL, title, and metadata of a web page. Ontological approaches along with local multilingual dictionaries are used as the knowledge base to facilitate the challenging task of blocking URLs not meeting the filtering criteria. The proposed work shows high accuracy in classifying multilingual URLs into two categories, white and black. Evaluation results conducted on a large dataset show that the proposed system achieves promising accuracy, which is on a par with those achieved in state-of-the-art literature on semantic-based URL filtering.  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