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景观生态学是20世纪70年代以后蓬勃发展起来的一门新兴的交叉学科。介绍了当前城市景观设计现状,并对此作了初步性探究。同时引入景观生态学对城市景观设计的影响,认为景观生态学将促使今后的景观设计更具科学性和完整性。 相似文献
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Wa Kues 《Reproduction in domestic animals》2000,35(6):253-254
Contents Recent advances in molecular and cellular techniques highlight the potential use of different kinds of somatic, as well as embryonic and adult stem cell types in efficient and rapid in vitro test systems. The rapidly progressing genome sequencing projects will permit studies based on sequence‐defined cell lines. Thus a combination of genomic data, molecular tools and appropriate cells together with a spectrum of high throughput analysis methods, such as cDNA arrays, two‐hybrid analysis, Maldi‐TOF spectrometry and protein chips will produce powerful test systems for target gene, as well as target protein identification and for toxicological and pharmacogenetic testing. These studies will be performed first in vitro but subsequently cellular test systems will additionally be required. The modern cell factory allows the researcher to answer specific questions about the role of genes, proteins and metabolites, as well as several other factors. The employment of embryonic stem cells and sophisticated methods to direct their differentiation towards desired mature cell types or differentiation states, will allow investigation into the molecular switches controlling embryonic development, differentiation, tumorigenicity and teratogenicity. The topic of this article is whether cell‐based systems could be an alternative to the usage of animal, or more precisely whether cell‐based systems could probably be the better alternative? 相似文献
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It is proposed that Saturn's satellite Titan is covered by an ocean one to several kilometers deep consisting mainly of ethane. If the ocean is in thermodynamic equilibrium with an atmosphere of 3 percent (mole fraction) methane, then its composition is roughly 70 percent ethane, 25 percent methane, and 5 percent nitrogen. Photochemical models predict that ethane is the dominant end product of methane photolysis so that the evolving ocean is both the source and sink for continuing photolysis. The coexisting atmosphere is compatible with Voyager data. 相似文献
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本文对托县小茴香果实进行了比较全面的营养成份测定,并对数据进行研究分析。测定结果表明:小茴香果实营养丰富,含蛋白质18.98%;脂肪16.22%,V_E2.677mg/100g,V_B1.60mg/100g,Se0.476mg/kg,胡萝卜素2.796mg/100g,还含有17种氨基酸及多种微量元素,总能量高达4995kCUI/kg,这将为进一步合理开发利用小茴香资源提供有力的依据。 相似文献
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测土施肥技术对内蒙古通辽市玉米养分管理的影响现状与评价 总被引:1,自引:0,他引:1
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介绍了热扩散探针方法(TDP)测定树干液流的基本原理,并综述了热扩散探针法在树木单株液流与耗水特征及其影响因素、林分蒸腾耗水量估计等研究中的应用现状,最后阐述了树干液流研究中存在的问题及展望. 相似文献
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The DNA origami method, in which long, single-stranded DNA segments are folded into shapes by short staple segments, was used to create nucleic acid probe tiles that are molecular analogs of macroscopic DNA chips. One hundred trillion probe tiles were fabricated in one step and bear pairs of 20-nucleotide-long single-stranded DNA segments that act as probe sequences. These tiles can hybridize to their targets in solution and, after adsorption onto mica surfaces, can be examined by atomic force microscopy in order to quantify binding events, because the probe segments greatly increase in stiffness upon hybridization. The nucleic acid probe tiles have been used to study position-dependent hybridization on the nanoscale and have also been used for label-free detection of RNA. 相似文献