共查询到20条相似文献,搜索用时 34 毫秒
1.
2.
《人与生物圈》1996,(2)
1. The background is a maple leaf, whose vein is the transformation of the first letter of "Jiu", that is J. In the front, there is a waterfall, which is the transformati on of Z, the first letter of Zhai. This makes "Jiuzhai" obvious. The first letter of China, "C", is transformed into a globe, symbol- 相似文献
3.
4.
Petsko GA 《Genome biology》2004,5(5):106-3
Anyone who cares about the moral and social implications of genomics, genetic engineering and biotechnology should read Michael J. Sandel's article, 'The Case Against Perfection', in the April 2004 issue of The Atlantic Monthly. 相似文献
5.
6.
《中国实验动物学报》2005,(Z1)
The first case of severe acute respiratory syndrome(SARS)in Guangdong province was reported on2Jan2003,whileretrospective survey has datedthe first index case on16Nov2002.In months that followed,pandemic of SARS widelyspread over the world until July2003,infecting8454people and claiming908deathsin39countries andregions global-ly.On16Dec2003,a32years old photographerlivinginsuburban Guangzhou presented withsymptoms of SARSinfec-tion.There were3other ensuing cases betweenthe end of2003and… 相似文献
7.
8.
9.
10.
This paper explains the objectives of organising the symposium ‘The Other North Sea’. A major goal is the submission of the
conclusions and content of this symposium to the North Sea Task Force, an initiative of the Second Conference on the Protection
of the North Sea (London, 1987) which is responsible for preparing a Quality Status Report on the North Sea by mid-1993. The
conclusions and recommendations of the symposium are summarised and presented to the North Sea Task Force in connection with
the preparations for the 1993 Quality Status Report. The paper stresses the need to subdivide the North Sea into areas of
ecological entity and underlines the advantages of using diatom and meiofauna assemblages as indicators for present and past
environmental actors in sediment conditions. A plea is also made for the promotion of research to improve understanding of
disturbance of sensory perception and behaviour as an ecologically relevant early warning signal. The major role of fisheries
in inducing changes of seabird and harbour porpoise populations is highlighted. 相似文献
11.
12.
13.
1. The rates of deacylation of acyl-alpha-chymotrypsins in which the hydrogen-bonding capacity of the acylamino group of the substrate has been systematically removed were measured. 2. The ratio of deacylation rates of l- and d-acyl-enzymes is found to depend largely on the existence in the substrate of an amido -NH- group. 3. The data presented agree with the postulate that the stereospecificity of alpha-chymotrypsin is exercised in catalytic rather than binding steps, and that the active site of the enzyme presents three loci to the substrate: the site containing the catalytic functionalities (including serine-195), the hydrophobic area for amino acid side-chain binding, and a hydrogen-bond acceptor site for acylamino group binding. 4. It is noted that, though the hydrogen-bonding site is crucial for the stereospecificity, the free energy of binding of substrates and inhibitors is dominated by the hydrophobic interaction. 5. It is tentatively proposed that alpha-chymotrypsin selects a high-energy conformation of the substrate when the latter binds at the enzyme's active site. 相似文献
14.
Jay Odenbaugh 《Biology & philosophy》2006,21(5):607-621
In this essay, I argue for four related claims. First, Richard Levins’ classic “The Strategy of Model Building in Population
Biology” was a statement and defense of theoretical population biology growing out of collaborations between Robert MacArthur,
Richard Lewontin, E. O. Wilson, and others. Second, I argue that the essay served as a response to the rise of systems ecology
especially as pioneered by Kenneth Watt. Third, the arguments offered by Levins against systems ecology and in favor of his
own methodological program are best construed as “pragmatic”. Fourth, I consider limitations of Levins’ arguments given contemporary
population biology.
相似文献
Jay OdenbaughEmail: |
15.
S. Morimoto K. Kawashiro H. Yoshida 《Origins of life and evolution of the biosphere》1977,8(4):341-346
The mixture of -aminopropionitrile and ,-iminodipropionitrile polymerized to solidify almost at the temperature near 0°C during 8 years. The conversions based on decreasing of those reactants were 61 and 98% at 4 and 8 years, respectively. The fractionation of 4 and 8 years product using Sephadex G 10 yielded their predominant amounts in the oligomer and polymer section, respectively. The oligomer section product of 8 years product was analyzed by means of ion exchange chromatography and its trimethylsilyl derivative was also analyzed by means of gas chromatography combined with mass spectrometry. These results identified dialanine and trialanine and their amides and nitriles. 相似文献
16.
Scoble MJ 《Trends in ecology & evolution》1997,12(12):465-466
17.
18.
19.
20.