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   93篇
  免费   0篇
  国内免费   1篇
丛书文集   2篇
教育与普及   1篇
现状及发展   31篇
研究方法   3篇
综合类   57篇
  2019年   1篇
  2016年   1篇
  2014年   1篇
  2013年   1篇
  2012年   3篇
  2011年   6篇
  2010年   2篇
  2008年   4篇
  2007年   5篇
  2006年   5篇
  2005年   2篇
  2004年   6篇
  2003年   3篇
  2002年   9篇
  2001年   2篇
  2000年   4篇
  1993年   1篇
  1992年   4篇
  1991年   5篇
  1990年   1篇
  1987年   4篇
  1986年   2篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1980年   1篇
  1979年   2篇
  1975年   1篇
  1974年   2篇
  1972年   5篇
  1967年   3篇
  1966年   1篇
  1965年   3篇
排序方式: 共有94条查询结果,搜索用时 15 毫秒
51.
The late survival of archaic hominin populations and their long contemporaneity with modern humans is now clear for southeast Asia. In Europe the extinction of the Neanderthals, firmly associated with Mousterian technology, has received much attention, and evidence of their survival after 35 kyr bp has recently been put in doubt. Here we present data, based on a high-resolution record of human occupation from Gorham's Cave, Gibraltar, that establish the survival of a population of Neanderthals to 28 kyr bp. These Neanderthals survived in the southernmost point of Europe, within a particular physiographic context, and are the last currently recorded anywhere. Our results show that the Neanderthals survived in isolated refuges well after the arrival of modern humans in Europe.  相似文献   
52.
Mantle wedge control on back-arc crustal accretion   总被引:1,自引:0,他引:1  
Martinez F  Taylor B 《Nature》2002,416(6879):417-420
At mid-ocean ridges, plate separation leads to upward advection and pressure-release partial melting of fertile mantle material; the melt is then extracted to the spreading centre and the residual depleted mantle flows horizontally away. In back-arc basins, the subducting slab is an important control on the pattern of mantle advection and melt extraction, as well as on compositional and fluid gradients. Modelling studies predict significant mantle wedge effects on back-arc spreading processes. Here we show that various spreading centres in the Lau back-arc basin exhibit enhanced, diminished or normal magma supply, which correlates with distance from the arc volcanic front but not with spreading rate. To explain this correlation we propose that depleted upper-mantle material, generated by melt extraction in the mantle wedge, is overturned and re-introduced beneath the back-arc basin by subduction-induced corner flow. The spreading centres experience enhanced melt delivery near the volcanic front, diminished melting within the overturned depleted mantle farther from the corner and normal melting conditions in undepleted mantle farther away. Our model explains fundamental differences in crustal accretion variables between back-arc and mid-ocean settings.  相似文献   
53.
54.
目的:初步了解龙街乡小兽类哺乳动物分布及蠕虫寄生情况。方法:鼠笼、鼠夹或投药捕获小兽分类鉴定,解剖检查蠕虫寄生情况。结果:共捕获小兽475只,小兽以黄胸鼠为优势种(44.84%),蠕虫总感染率为53.89%。结论:该乡小兽蠕虫感染普遍。  相似文献   
55.
芦荟冰淇淋的研制   总被引:1,自引:0,他引:1  
在冰淇淋中添加芦荟凝胶粉 ,使冰淇淋具有芦荟的保健和养颜特性 ,并且能提高冰淇淋混合料液的粘度以及冰淇淋的膨胀率和抗融性 .  相似文献   
56.
The transport of non-aqueous phase liquids (NAPLs) in unsaturated soils and groundwater is an important research topic in geo-environmental engineering. In this paper, the mechanism of light NAPLs (LNAPLs) transport in subsurface system is briefly introduced, and the mass transport equations, fluid flow equations, and the constitutive model of relative permeability - saturation - capillary pressure are discussed. Then the numerical method is introduced to simulate the multiphase flow problems in porous media, and the tempo-spatial distribution of LNAPLs is obtained. Moreover, different boundary conditions are employed in numerical simulation to investigate its effect on transport behavior. To verify the numerical data, centrifugal tests are conducted to model the LNAPLs migration in unsaturated soils and groundwater. The calculation results are agreeable with the experimental findings of centrifugal modeling, which indicates that LNAPLs from leaking point move downwards due to gravity force, and form a high concentration zone above the capillary fringe, and then spread out laterally along the groundwater table. Some LNAPL enters groundwater system to further migrate. The combination of numerical simulation and centrifuge modeling can be a useful means to study the transport behavior of LNAPLs in subsurface system.  相似文献   
57.
58.
59.
60.
J R Martinez  J Camden 《Experientia》1986,42(9):1005-1006
Equivalent spaces of 42K were measured in fragments of the submandibular gland of 1-, 7-, 14- and 21-day-old and adult rats in the absence and presence of carbachol and the transport inhibitors ouabain and furosemide. The results indicate that the 42K space was increased by carbachol in an ouabain-sensitive manner at all ages studied and that part of the secretagogue-stimulated K uptake occurred by way of a furosemide-sensitive transport system in the latter part of the postnatal period and in the adult.  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