排序方式： 共有10条查询结果，搜索用时 140 毫秒
1
1.
2.
3.
4.
Seasonal changes in abundance, growth and mortality of heterotrophic bacteria were investigated monthly from collections and
dilution experiments in Kagoshima Bay, the southernmost of Japan. Bacteria occurred abundantly with considerable variation
in the surface layers where chlorophyll a concentrations were high, whereas seasonal variations were obscure below 100 m. Especially, bacteria showed a decline of
cell density toward summer when heterotrophic nano-flagellates increased their abundance. Seasonal and vertical variations
in bacterial cell number during the study period were positively correlated with those of water temperature and pico-sized
chlorophyll a concentration. Maximum growth and mortality rates showed positive correlations with water temperature but no positive relationships
to size-fractionated chlorophyll a. Net increase rate (i.e. in situ rate if abundance changes) was negatively correlated with cell density of heterotrophic nano-flagellates. It is concluded
that bacterial abundance is controlled by the resultant (i.e. net growth rate) of the balance between maximum growth and predatory
mortality by heterotrophic nano-flagelllates which are both dependent on ambient temperature. 相似文献
5.
Chiaki Hikage Kazuya Koyama Takahiko Matsubara Tomo Takahashi Masahide Yamaguchi 《Monthly notices of the Royal Astronomical Society》2009,398(4):2188-2198
We study the effect of primordial isocurvature perturbations on non-Gaussian properties of cosmic microwave background (CMB) temperature anisotropies. We consider generic forms of the non-linearity of isocurvature perturbations which can be applied to a wide range of theoretical models. We derive analytical expressions for the bispectrum and the Minkowski Functionals for CMB temperature fluctuations to describe the non-Gaussianity from isocurvature perturbations. We find that the isocurvature non-Gaussianity in the quadratic isocurvature model, where the isocurvature perturbation S is written as a quadratic function of the Gaussian variable σ, S =σ2 −〈σ2 〉 , can give the same signal-to-noise ratio as f NL = 30 even if we impose the current observational limit on the fraction of isocurvature perturbations contained in the primordial power spectrum α. We give constraints on isocurvature non-Gaussianity from Minkowski Functionals using the Wilkinson Microwave Anisotropy Probe ( WMAP ) 5-year data. We do not find a significant signal of isocurvature non-Gaussianity. For the quadratic isocurvature model, we obtain a stringent upper limit on the isocurvature fraction α < 0.070 (95 per cent CL) for a scale-invariant spectrum which is comparable to the limit obtained from the power spectrum. 相似文献
6.
7.
8.
9.
Abstract. The distribution of M. muelleri eggs throughout the Adriatic Sea were studied in relation to environmental conditions. Eggs were present in all seasons, with the highest concentrations in the small region of the Jabuka pit (273m depth). The authors point out that the geomorphological, hydrographic and trophic conditions in this small region of the Adriatic are favourable for the presence of greater M. muelleri populations. 相似文献
10.
1