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   157篇
  免费   14篇
  国内免费   5篇
电工技术   5篇
综合类   9篇
化学工业   17篇
机械仪表   8篇
建筑科学   1篇
矿业工程   4篇
能源动力   4篇
轻工业   52篇
石油天然气   3篇
无线电   16篇
一般工业技术   7篇
冶金工业   2篇
原子能技术   1篇
自动化技术   47篇
  2024年   1篇
  2023年   2篇
  2022年   8篇
  2021年   7篇
  2020年   4篇
  2019年   7篇
  2018年   5篇
  2017年   8篇
  2016年   8篇
  2015年   3篇
  2014年   7篇
  2013年   9篇
  2012年   17篇
  2011年   9篇
  2010年   20篇
  2009年   9篇
  2008年   7篇
  2007年   7篇
  2006年   14篇
  2005年   8篇
  2004年   4篇
  2003年   3篇
  2002年   1篇
  2001年   2篇
  2000年   2篇
  1997年   1篇
  1996年   1篇
  1994年   1篇
  1988年   1篇
排序方式: 共有176条查询结果,搜索用时 15 毫秒
1.
通过向灰树花发酵体系中单一添加天麻醇提物、苦荞醇提物及两种提取物的复配液,研究其对灰树花菌体生长和胞外多糖合成的影响,同时对添加复配液后发酵体系中的残糖(还原糖)含量、pH值的动态变化进行研究。结果表明:当复配液中天麻醇提物添加量为7 g/L、苦荞醇提物添加量为5 g/L时效果较佳,相比空白组(未添加提取物)和单一添加组(天麻、苦荞),胞外多糖产量分别增加了49.08%、13.76%、33.88%,菌丝体生物量分别增加了51.10%、11.35%、26.69%,均显著地高于空白组(P<0.01)和单一添加组(P<0.05)。发酵动力学研究表明,灰树花菌体生长和胞外多糖产量在第7天达到峰值,复配组相对于空白组能消耗更多的碳源物质促进胞外多糖的合成。因此,天麻和苦荞中的有效成分能够显著促进灰树花菌体生长与胞外多糖的合成。  相似文献   
2.
ERP—实现制造企业资源信息化管理的有效途径   总被引:1,自引:1,他引:1  
介绍了ERP(企业资源计划管理 )的概念 ,分析了制造企业实施ERP的必要性。对制造企业ERP的系统功能组成和实施模式进行了详细论述 ,最后分析了其发展趋势  相似文献   
3.
Epidemiological and experimental studies provide supportive evidence that lutein, a major carotenoid, may act as a chemopreventive agent against atherosclerosis, although the underlying molecular mechanisms are not well understood. The main aim of this study was to investigate the effects of lutein on the alleviation of atherosclerosis and its molecular mechanisms involved in oxidative stress and lipid metabolism. Male apolipoprotein E knockout mice (n = 55) were fed either a normal chow diet or a high fat diet (HFD) supplemented with or without lutein for 24 weeks. The results showed that a HFD induced atherosclerosis formation, lipid metabolism disorders and oxidative stress, but noticeable improvements were observed in the lutein treated group. Additionally, lutein supplementation reversed the decreased protein expression of aortic heme oxygenase‐1 and increased the mRNA and protein expressions of aortic nicotinamide‐adenine dinucleotide phosphate oxidase stimulated by a HFD. Furthermore, the decreased mRNA and protein expression levels of hepatic peroxisome proliferator‐activated receptor‐α, carnitine palmitoyltransferase 1A, acyl CoA oxidase 1, low density lipoprotein receptors and scavenger receptor class B type I observed in mice with atherosclerosis were markedly enhanced after treatment with lutein. Taken together, these data add new evidence supporting the anti‐atherogenic properties of lutein and describing its mechanisms of action in atherosclerosis prevention, including oxidative stress and lipid metabolism improvements.  相似文献   
4.
5.
目的 分析评价云南小草坝新鲜天麻中9种金属元素含量水平。方法 采用电感耦合等离子体质谱法检测云南小草坝新鲜天麻中铁Fe、铜Cu、钴Co、锰Mn、镍Ni、硒Se、砷As、铅Pb、汞Hg的含量, 并使用食品安全指数IFS法进行重金属污染评价。结果 云南小草坝新鲜天麻中各元素均检出, 参照《现行药用植物及制剂进出口绿色行业标准》及《中国药典》2015年版中重金属限量值判定, 54份天麻中Cu、Pb、As、Hg的含量均没有样品超过限量指标。按照GB 2762-2012食品标准进行判定, Pb有40.7%的超标率, As、Hg均未出现超标样品。小草坝产区新鲜天麻中As、Pb、Hg的IFS值均小于1。结论 云南小草坝新鲜天麻中微量元素丰富, 食品安全风险整体上在可接受范围, 但仍需关注可能存在的铅污染水平。  相似文献   
6.
介绍了出口伊朗的DF8B I型电传动内燃机车的总体布置、技术特点、主要技术参数、牵引性能和关键技术攻关。  相似文献   
7.
对龙芽葱木采用真空冷冻干燥生产技术处理,通过温度、厚度实验使干燥时间与生产能力达到最好效果。外形美观,复水快、复水率高。  相似文献   
8.
A novel way is proposed to fulfill Kronecker delta condition in moving least squares (MLS) approximation along the essential boundary. In the proposed scheme, the original MLS weight is modified to boundary interpolatable (BI) weight based on the observation that the support of weight function is exactly the same as the support of MLS nodal shape function. The BI weight is zero along the boundary edges except the edges containing the nodal point associated with the concerned weight. In order to construct the BI weight from the original weight, concept of edge distance function is introduced, and the BI weight construction procedure is presented in detail. Furthermore, it is explained theoretically why the MLS nodal shape functions obtained by BI weights satisfy Kronecker delta condition along the boundary edges. To identify the validity and usefulness of the proposed BI MLS approximation scheme through numerical tests, the scheme is applied to the model problems with rectangular domain and complex shaped domain. Through the tests, theoretical prediction is identified numerically, and it is confirmed that one can handle the essential and natural boundary conditions through the proposed BI MLS scheme in exactly the same manner used in traditional finite element methods.  相似文献   
9.
In this paper, a special purpose algorithm for solving large eigenvalue problems based on the Lanczos method is successfully applied to an engineering problem: the electromagnetic analysis and design of passive waveguide devices. For dealing with such complex problems, the boundary integral‐resonant mode expansion (BI‐RME) technique has been recently proposed. This technique solves integral equations (IEs) through the well‐known method of moments (MoM), thus leading to structured eigenvalue problems. These problems frequently become very large when solving complex arbitrary geometries with high accuracy. In such cases, the eigenvalue problem cannot be efficiently solved with standard methods by means of personal computers, essentially due to CPU time and memory allocation requirements. In this paper, we propose an alternative technique, based on the Lanczos method, for the fast and accurate solution of large BI‐RME generalized eigenvalue problems. The novel theoretical aspects of this approach, as well as the impacton the original BI‐RME formulation, are described. Comparative benchmarks are also successfully presented for the full‐wave analysis and design of real passive microwave devices. Copyright © 2005 John Wiley Sons, Ltd.  相似文献   
10.
This study examines the role of the decision environment in how well business intelligence (BI) capabilities are leveraged to achieve BI success. We examine the decision environment in terms of the types of decisions made and the information processing needs of the organization. Our findings suggest that technological capabilities such as data quality, user access and the integration of BI with other systems are necessary for BI success, regardless of the decision environment. However, the decision environment does influence the relationship between BI success and capabilities, such as the extent to which BI supports flexibility and risk in decision making.  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