全文获取类型
收费全文 | 130篇 |
免费 | 8篇 |
出版年
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2013年 | 4篇 |
2012年 | 7篇 |
2011年 | 5篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 2篇 |
2007年 | 6篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2002年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 9篇 |
1997年 | 2篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1972年 | 4篇 |
1971年 | 2篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1958年 | 2篇 |
1957年 | 3篇 |
1956年 | 6篇 |
1955年 | 1篇 |
1954年 | 1篇 |
1952年 | 1篇 |
1951年 | 2篇 |
1950年 | 6篇 |
1949年 | 2篇 |
1948年 | 2篇 |
1947年 | 1篇 |
1933年 | 1篇 |
排序方式: 共有138条查询结果,搜索用时 578 毫秒
61.
In a number of recent field studies, the positive response of soil respiration to warming has been shown to decline over time. The two main differing hypotheses proposed to explain these results are: (1) soil microbial respiration acclimates to the increased temperature, and (2) substrate availability within the soil decreases with warming so reducing the rate of soil respiration. To investigate the relative merits of these two hypotheses, soil samples (both intact cores and sieved samples) from a 3-year grassland soil-warming and shading experiment were incubated for 4 weeks at three different temperatures under constant laboratory conditions. We tested the hypothesis that sieving the soils would reduce differences in substrate availability between warmed and control plot samples and would therefore result in similar respiration rates if microbial activity had not acclimated to soil warming. In addition, to further test the effect of substrate availability, we compared the respiration rates of soils taken from shaded and unshaded plots. Both soil warming and shading significantly reduced respiration rates in the intact cores, especially under higher incubation temperatures. However, sieving the soil greatly reduced these differences suggesting that substrate availability, and not microbial acclimation to the higher temperatures, played the dominant role in determining the response of heterotrophic soil respiration to warming. The effect of shading appeared to be mediated by reduced plant productivity affecting substrate availability within the soil and hence microbial activity. Given the lack of evidence for thermal acclimation of microbial respiration, there remains the potential for prolonged carbon losses from soils in response to warming. 相似文献
62.
63.
Catechol 2, 3-dioxygenase is present in several types of bacteria and undergoes degradation of environmental pollutants through
an important key biochemical pathways. Specifically, this enzyme cleaves aromatic rings of several environmental pollutants such
as toluene, xylene, naphthalene and biphenyl derivatives. Hence, the importance of Catechol 2, 3-dioxygenase and its role in the
degradation of environmental pollutants made us to predict the three-dimensional structure of Catechol 2, 3-dioxygenase from
Burkholderia cepacia. The 10ns molecular dynamics simulation was carried out to check the stability of the modeled Catechol 2, 3-
dioxygenase. The results show that the model was energetically stable, and it attains their equilibrium within 2000 ps of production
MD run. The docking of various petroleum hydrocarbons into the Catechol 2,3-dioxygenase reveals that the benzene, O-xylene,
Toluene, Fluorene, Naphthalene, Carbazol, Pyrene, Dibenzothiophene, Anthracene, Phenanthrene, Biphenyl makes strong
hydrogen bond and Van der waals interaction with the active site residues of H150, L152, W198, H206, H220, H252, I254, T255,
Y261, E271, L276 and F309. Free energy of binding and estimated inhibition constant of these compounds demonstrates that they
are energetically stable in their binding cavity. Chrysene shows positive energy of binding in the active site atom of Fe. Except
Pyrene all the substrates made close contact with Fe atom by the distance ranges from 1.67 to 2.43 Å. In addition to that, the above
mentioned substrate except pyrene all other made π-π stacking interaction with H252 by the distance ranges from 3.40 to 3.90 Å.
All these docking results reveal that, except Chrysene all other substrate has good free energy of binding to hold enough in the
active site and makes strong VdW interaction with Catechol-2,3-dioxygenase. These results suggest that, the enzyme is capable of
catalyzing the above-mentioned substrate. 相似文献
64.
65.
66.
67.
68.
69.
70.
Luke B Chenoweth Simon M Tierney Jaclyn A Smith Steven JB Cooper Michael P Schwarz 《BMC evolutionary biology》2007,7(1):246