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61.
我国奶牛场收入政策及发展 总被引:1,自引:0,他引:1
叙述了我国目前乳业概况,就经济体制转变以来,我国的奶生产情况,牧场收入,政府所起的作用及乳业今后面临的挑战等问题进行了分析和论述。 相似文献
62.
63.
后工业时代米兰单功能城区更新 总被引:1,自引:0,他引:1
在物化的形式上,解释米兰城市发展历史上的单功能城区的改造意义,并由此分析单功能城区更新的经验:单功能城区向混合居住模式的更新是发展方向;城区的功能重新定义对城区发展有重要意义;以新的建设为基础,发展城区自身的特色,做到城市在更新和特色之间的协调。 相似文献
64.
Johanna Bakker Colin F. Timberlake 《Journal of the science of food and agriculture》1985,36(12):1315-1324
The distribution of anthocyanins in methanolic skin extracts of 16 grape cultivars used for port wine production and grown at five sites in the Douro Valley in Northern Portugal has been assessed by high performance liquid chromatography. Results are confined to the seven most readily separated and identified anthocyanins and are expressed as percentages of their total (88–99% of the total integrated area). Anthocyanins based on malvidin (Mv) predominated. Of these, Mv 3-glucoside was the major pigment (33–60%), being exceeded by Mv 3-p-coumarylglucoside (2–51%) in only two cultivars; Mv 3-acetylglucoside (1–15%) was consistently the lowest. Peonidin 3-glucoside (1–27%) was prominent in four cultivars, but delphinidin 3-glucoside (1–11%), petunidin 3-glucoside (2–11%) and cyanidin 3-glucoside (trace-6%) were of low proportions throughout. The ratio Mv 3-acetylglucoside/total Mv glucosides appeared characteristic of cultivar, independent of site, and a useful aid to identification of grape cultivars. The coloured pulp of some cultivars contained peonidin 3-glucoside as a major component, present in greater proportions than in the skin; the percentage of Mv 3-p-coumarylglucoside was lower in pulp than in skin. The identities of six of the seven anthocyanins were confirmed by fast atom bombardment mass spectrometry and the structures of the Mv derivatives were determined by nuclear magnetic resonance. The formation of formyl and acetyl anthocyanin artefacts is described. 相似文献
65.
Domenico Ferrari 《Multimedia Systems》1998,6(3):179-185
The research done by the Tenet Group in multimedia networking has reached a point where it may be useful to reflect on the
significance of its results for the current debate on how integrated-services internetworks should be designed. Such reflections
constitute the main subject of this paper. The principles of the work and the conclusions reached so far by the Tenet researchers
are discussed in the light of the conflict between the two major technologies being proposed to build future information infrastructures:
namely, the Internet and the ATM technologies. The Tenet approach suggests one feasible way for resolving the conflict to
the advantage of all the users of those infrastructures. This paper discusses various fundamental aspects of integrated-services
network design: the choice of the service model, the type of charging policy to be adopted, and the selection of a suitable
architecture. 相似文献
66.
不同于无标度网络,小世界网络中体现负载特性的介数分布和体现连接特征的度分布这两种结构差异很大,依据这个差异,我们提出了有效的删边扩容方法并进行了仿真实验,并进一步从容量与最大介数的关系理论分析确证了实验结果.接着,我们分析了小世界网络中介数分布的差异性与删边扩容效果的相关性,把基于介数的基尼系数变化用于度量删边扩容的效果,指出了结构差异是导致删边扩容效应的必要条件.还指出了无论从容量与介数的定义、仿真结果、结构差异与删边扩容效果的关系来看,都应该从介数入手来实现删边扩容方法,这种方法反直觉,有很多变种,并且实现方便、节省成本,作为一类新的路由策略可以广泛地应用于各类通信网络和交通网络等领域. 相似文献
67.
Providing performance guarantees for arriving traffic flows has become an important measure for today’s routing and switching systems. However, none of current scheduling algorithms built on CICQ (combined input and cross-point buffered) switches can provide flow level performance guarantees. Aiming at meeting this requirement, the feasibility of implementing flow level scheduling is discussed thoroughly. Then, based on the discussion, it comes up with a hybrid and stratified fair scheduling (HSFS) scheme, which is hierarchical and hybrid, for CICQ switches. With HSFS, each input port and output port can schedule variable length packets independently with a complexity of O(1). Theoretical analysis show that HSFS can provide delay bound, service rate and fair performance guarantees without speedup. Finally, we implement HSFS in SPES (switch performance evaluation system) to verify the analytical results. 相似文献
68.
《中国科学:信息科学(英文版)》2012,(1):149-164
It is significant to automatically detect and resolve the incompliance in security policy.Most existing works in this field focus on compliance verification,and few of them provide approaches to automatically correct the incompliant security policies.This paper proposes a novel approach to automatically transform a given security policy into a compliant one.Given security policy Π and delegation policy M declared by logic programs,the approach automatically rewrites Π into a new one ΠM which is compliant with M and is readable by the humans.We prove that the algorithm is sound and complete under noninterference assumption.Formally,we show that the security policy query evaluation algorithm with conflict and unsettlement resolution still works very well on ΠM.The approach is automatic,so it doesn’t require a administrator with excess abilities.In this sense,our proposal can help us to save much manpower resource in security management and improves the security assurance abilities. 相似文献
69.
在WebServices应用中,保证数据交换传输的安全性和完整性非常重要,而当前技术下的WebServices却在安全性方面存在着一些不足。为了保护在WebServices中消息交换的安全传递,文中通过X.509证书实现了WebServices消息签名和加密,阐述了利用WSE3.0构建安全WebServices的方法,设计并实现了一种基于策略的可扩展系统安全架构,其中采用了证书管理、数据同步以及用户校验三种机制。在实现架构的过程中,将安全通信主体分为Web服务端和服务应用端,并通过对系统安全性的分析验证,证明此架构具有良好的安全性。随着信息化技术的发展,安全架构中安全策略的应用会越来越广泛和深入。 相似文献
70.
邹菊红 《电脑编程技巧与维护》2012,(22):98-99,123
根据定量装车过程中复杂的工艺参数监视和设备控制问题,提出了一种基于Modbus协议的自动监控系统。实现上位机服务端与上位机客户端之间的数据通讯,以及上位机客户端与下位机之间的监控。主要介绍了该系统的软件部分的设计和实现,并完整阐述了Modbus协议命令的实现。 相似文献