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   13篇
  免费   0篇
现状及发展   5篇
综合类   7篇
自然研究   1篇
  2019年   1篇
  2015年   1篇
  2014年   1篇
  2013年   2篇
  2012年   2篇
  2011年   1篇
  2001年   1篇
  1980年   1篇
  1979年   2篇
  1978年   1篇
排序方式: 共有13条查询结果,搜索用时 15 毫秒
1.
通过对美国格林斯堡镇与我国汶川灾区灾后重建工作进行对比,比较其规划制定流程、内容及执行过程的异同,并对重建效果进行分析.分析显示,1)在规划制定方面,美国采取"自下而上"方式,我国采取"自上而下"方式;2)在规划内容方面,美国以细节到整体的积累方式形成,我国以从框架到内容的填充方式完成;3)在执行过程中,美国的政府、社区、非盈利机构、基金会等组织合作密切且公众参与度高,我国采用的对口支援政策有利于集中优势以提高工作效率.  相似文献   
2.
Summary The pronormoblasts and normoblasts in Swiss albino mice were found to be very sensitive to radiation and their percentage was reduced drastically after exposure to gamma-rays. The degree of damage increased with increase in radiation dose. MPG reduced the initial damage and brought about an early and fast recovery. It is concluded that the drug protects the stem cells and thereby reduces the depletion of the regenerating pool which causes a more efficient and accelerated recovery.  相似文献   
3.
以美国堪萨斯州绿堡镇龙卷风灾区和中国汶川地震灾区灾后重建工作为例,选择具有代表性的两个研究区——美国堪萨斯州绿堡镇和四川省平武县南坝镇为研究区,从宏观和微观角度出发,采用文献研究、问卷调查和数据统计分析的方法,对比分析二者在资金来源及使用成效在当地灾民认知方面的异同,并分析差异形成的可能原因,以期为中国灾后恢复重建工作的顺利展开提供借鉴和理论指导.  相似文献   
4.
5.
Summary It was found that the MPG partially protects the spleen against weight loss due to radiation, and exaggerates the compensatory reaction in the tissue during recovery. It is also concluded that MPG protects the stem cells in the spleen, which helps to restore the peripheral blood by extramedullary erythropoiesis.  相似文献   
6.
通过整理河北省1949—2000年间的冰雹灾害农作物损失的案例资料,利用统计仿真模拟软件Arena和Matlab等,分析了河北省农作物冰雹灾害年发生次数以及农作物损失(分为受灾、成灾、绝收3种程度)服从的统计规律,并依据统计反演得到的参数进行了冰雹灾害随机事件模拟,对河北省冰雹灾害风险进行了评估,发现河北省冰雹灾害造成的年均农作物单产损失约合1.9%.  相似文献   
7.
Averting biodiversity collapse in tropical forest protected areas   总被引:3,自引:0,他引:3  
The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses. As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world’s major tropical regions. Our analysis reveals great variation in reserve ‘health’: about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.  相似文献   
8.
During progression of atherosclerosis, myeloid cells destabilize lipid-rich plaques in the arterial wall and cause their rupture, thus triggering myocardial infarction and stroke. Survivors of acute coronary syndromes have a high risk of recurrent events for unknown reasons. Here we show that the systemic response to ischaemic injury aggravates chronic atherosclerosis. After myocardial infarction or stroke, Apoe-/- mice developed larger atherosclerotic lesions with a more advanced morphology. This disease acceleration persisted over many weeks and was associated with markedly increased monocyte recruitment. Seeking the source of surplus monocytes in plaques, we found that myocardial infarction liberated haematopoietic stem and progenitor cells from bone marrow niches via sympathetic nervous system signalling. The progenitors then seeded the spleen, yielding a sustained boost in monocyte production. These observations provide new mechanistic insight into atherogenesis and provide a novel therapeutic opportunity to mitigate disease progression.  相似文献   
9.
结合目前自然灾害应急物流的研究现状,指出了应急物流存在的问题.从物资需求、分配原则、路网风险以及配送方式的角度,分析了应急物流的特性.提出了自然灾害应急物流协调框架,它是灾害综合评估、灾民转移和应急物资配送在应急物流系统下的有机结合,是不同组织机构、不同利益主体、不同物流网络单元间职能、目标、信息、物资、车辆等的协调.  相似文献   
10.
IntroductionThehighTcsuperconductorsarelayeredmaterialswithCuO2 planes ,separatedbyinsulatingrock saltoxidelayers.TheimportanceoftheCuO2 planeshascreatedmajorinteresttostudytheelectronicandstructuralbehaviourofthesestructuralelementssincethediscoveryofth…  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