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   24篇
  免费   0篇
电工技术   4篇
化学工业   2篇
金属工艺   1篇
建筑科学   2篇
轻工业   2篇
水利工程   1篇
无线电   1篇
一般工业技术   2篇
冶金工业   7篇
自动化技术   2篇
  2022年   1篇
  2021年   1篇
  2020年   1篇
  2013年   1篇
  2012年   1篇
  2008年   3篇
  2007年   2篇
  2004年   1篇
  2002年   1篇
  1998年   3篇
  1996年   1篇
  1994年   2篇
  1993年   1篇
  1991年   3篇
  1978年   1篇
  1976年   1篇
排序方式: 共有24条查询结果,搜索用时 31 毫秒
1.
2.
3.
Poor performance of livestock that graze tall fescue (Festuca arundinacea Schreb.) has been associated with the endophyte fungus Neotyphodium coenophialum [Morgan-Jones and Gams] Glenn, Bacon, and Hanlin). Recent evidence suggests lowered Cu status and a depression of Cu-related immune function in steers that graze endophyte-infected (E+) tall fescue. Greenhouse and field studies investigated relationships between the endophyte and Cu concentrations in tall fescue. Seventeen infected 'Kenhy' clones were divided, and one plant of each pair was treated three times with Benomyl to remove the endophyte (E-). Plants were watered with nutrient solution in a greenhouse for 6 mo before sampling. Copper concentrations were greater (P < .001) in E- than in E+ clones (3.4 vs 2.8 microg/g; SE, .06). In the second greenhouse experiment, genetically similar E+ and E- 'Kentucky'-31 (KY-31) and 'Georgia Jessup' were grown from seed and fertilized with nutrient solution to produce mature plants. Copper concentrations were higher (P < .05) in E- than in E+ tall fescue (8.6 vs 7.6 microg/g; SE, .3). In a field plot experiment in Texas, E+ and E- KY-31 were grown with 0, 50, and 100% replacement of potential evapotranspiration. By September, Cu concentrations were higher (P < .05) in E- than in E+ tall fescue (7.3 vs 6.6 microg/g; SE, .2). In pasture experiments, KY-31 E+ (> 70% infection level) and E- (< 5% infection level) tall fescue were grown in Virginia at two locations with three rates of N fertilizer. Copper concentrations were higher (P < .05) in E- than in E+ tall fescue (4.8 vs 4.5 microg/g; SE, .1) and increased (P < .01) linearly in response to N. Our data demonstrate that the presence of the endophyte is associated with lower Cu concentrations in tall fescue, which may contribute to lowered Cu status in animals and thus contribute to the etiology of fescue toxicity.  相似文献   
4.
The deployment of small cells in mobile networks has aroused a large interest in the last few years. This paper investigates the impact of picocell deployment on the performance and power consumption of mobile networks. Since different network upgrades introduce different performance gains, comparing different configurations exclusively on their overall power consumption can be rather biased. For this reason, a new key performance indicator, termed “energy efficiency”, is introduced and used throughout this study, bringing together network performance and its overall power consumption. In the first section of the study, a theoretical analysis for the Erlang-like capacity of a network, considering a uniform topology and traffic, is performed, using queuing theory analysis, namely processor-sharing queues. Results show that in all cases the deployment of picocells improve the performance of the network, however the energy efficiency is noted to be dependent on the deployment scenario considered. In the second part of the study, a more realistic scenario with non-uniform topology and traffic is considered, which is carried out through a large-scale system level simulator. Results show that by deploying picocells in areas experiencing high levels of traffic, the energy efficiency of the network can be considerably improved.  相似文献   
5.
In this work, we assessed the in-vitro effects of eicosapentaenoic acid (EPA; C20:5n-3) and docosahexaenoic acid (DHA; C22:6n-3) (final concentration, 15 microM) on T cell blastogenesis, interleukin-2 and -4 (IL-2, IL-4) secretion, fatty acid composition and intracellular oxidative status in type I diabetic patients with or without complications. Con A stimulated lymphocyte proliferation, glucose uptake, intracellular reduced glutathione levels and catalase activity were lower in diabetics as compared to controls, regardless to the presence of complications. EPA and DHA diminished T-lymphocyte proliferation and IL-2 production but enhanced IL-4 secretion in both diabetic and control groups. No changes in the levels of reduced glutathione and in the activities of catalase and SOD were observed in control T cells cultured in the presence of EPA and DHA. However, in diabetic patients, addition of n-3 PUFA to culture induced an increase in T cell levels of reduced glutathione and hydroperoxide, and in activities of catalase and SOD. Low levels of arachidonic acid (C20:4n-6) were found in plasma membrane phospholipids of lymphocytes from diabetic patients compared to controls. Incubation of lymphocytes with EPA and DHA was associated with an incorporation of these fatty acids in membrane phospholipids. In conclusion, the beneficial effects of n-3 PUFA on T cell functions in type I diabetes could be attributed to their suppressive action and modulation of cytokine secretion, and to the improvement of intracellular oxidative status.  相似文献   
6.
A set of words X over a finite alphabet A is said to be unavoidable if all but finitely many words in A* have a factor in X. We examine the problem of calculating the cardinality of minimal unavoidable sets of words of uniform length; we correct an error in [8], state a conjecture offering a formula for the minimum size of these so called n-good sets for all values of n, and show that the conjecture is correct in an infinite number of cases.  相似文献   
7.
This paper presents a study of UK water industry capital equipment selection, focusing in particular on behaviour in relation to sewerage/combined sewer overflow (CSO) and wastewater‐associated investment activities. Valuable new insights into the perspectives of different parties, including water service providers (WSPs), design consultants and construction companies, are provided. Through analysis of over 200 questionnaires, equipment selection is confirmed to be multi‐organisational, with different parties dominating different roles. Among the selection criteria, service and quality are found to be valued as parameters worth paying for. Relationships and sustainability considerations are also found to be important, although views on whether sustainability benefits will be paid for are divided. While interparty alignment of views is generally good, there are occasional discrepancies at the individual water region level. It is suggested that optimisation might derive from recognising the significance of intangible components of the supplier offering, and managing relationships to allow these to be capitalised upon.  相似文献   
8.
9.
M and M-N coatings, where M is nearly the metal composition of Inconel 690 (57 at.% Ni, 32 at.% Cr, 9.5 at.% Fe…) were sputter-deposited on glass and steel substrates in pure argon and in Ar-N2 mixtures using a round planar magnetron. The influence of nitrogen gas flow rate inlet in argon on chemical composition and microstructure was studied. The as-deposited (T < 100 °C) M-N films containing up to 30 at.% nitrogen are a nanocrystalline supersaturated face cubic centered (fcc) solid solution (γN). The pure metallic films have a pronounced<111>fcc crystallographic texture, while the M-N films exhibit a strong<100>fcc crystallographic texture. The effect of temperature on the microstructure of M-N films was studied by increasing the substrate temperature during preparation and by tempering of an as-deposited M-N films. For M-N films prepared at 400 °C, the X-ray diffraction analysis reveals a magnetic γ phase with a very low nitrogen content, while electron probe microanalysis gives an overall high nitrogen content in the layer (up to 25 at.%). It is concluded that the layers consist of two phases when prepared or tempered at high temperature (T > 400 °C): an fcc CrN nitride and a γ (Ni,Fe,Cr) depleted in nitrogen.  相似文献   
10.
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