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91.
Starvation on changes in growth and fatty acid composition of juvenile red swamp crawfish, Procambarus clarkii 总被引:1,自引:0,他引:1
The effect of starvation on physiological and biochemical indicators of body, muscle and hepatopancreas were investigated for juvenile red swamp crawfish (Procambarus clarkii), and the results showed the effect was obvious. In a 70-day starvation experiment, mean body weight, exuvial rate, ab- dominal muscle ratio and hepatosomatic index decreased significantly. The percentage of protein, fat, ash and moisture were also significantly affected. The protein content decreased sharply at Day 30 onward and the percentage of fat decreased rapidly from Day 50 and on. The percentages of ash and moisture started to increase significantly at Day 40 and 30 respectively. After the starvation experiment, the hepa- topancreatic total and neutral lipid content decreased slightly from 23.90% to 20.39% and 73.75% to 70.35%, while the hepatopancreatic polar lipid content increased from 23.81% to 27.32%. On the other hand, all the muscular total, neutral and polar lipid contents, and the muscular fatty acid compositions did not change significantly except for the hepatopancreatic fatty acid composition. The relative percentages of 14:0, 16:0, 16:1n-7 and 18:1n-9 were decreased by 55.17%, 11.11%, 8.5% and 6.70% from the initial values, and the relative percentages of 18:2n-6, 18:3n-3, 20:4n-6, 20:5n-3 and 22:6n-3 increased obvi- ously from 5.2%, 3.9%, 2.4%, 10.6%, and 13.7% to 7.1%, 5.0%, 2.8%, 11.5%, and 14.4% respectively. Preference of utilization of fatty acids from hepatopancreas during starvation was as follows: 14:0>16:0>16:1n-7>18:1n-9, and the conservation of highly unsaturated fatty acids was in the order of: 18:2n-6 >18:3n-3>20:4n-6>20:5n-3>22:6n-3. 相似文献
92.
John H. Parkinson R. S. Wolff H. L. Kestenbaum W. H.-M. Ku J. R. Lemen K. S. Long R. Novick R. J. Suozzo M. C. Weisskopf 《Solar physics》1978,60(1):123-136
New observations of solar flare and active region X-ray spectra obtained with the Columbia University instrument on OSO-8 are presented and discussed. The high sensitivity of the graphite crystal panel has allowed both line and continuum spectra to be observed with moderate spectral resolution. Observations with higher spectral resolution have been made with a panel of pentaerythritol crystals. Twenty-nine lines between 1.5 and 7.0 Å have been resolved and identified, including several dielectronic recombination satellite lines to Si xiv and Si xiii lines which have been observed for the first time. It has been found that thermal continuum models specified by single values of temperature and emission measure have fitted the data adequately, there being good agreement with the values of these parameters derived from line intensity ratios. 相似文献
93.
Analysis of ^232Th, ^230Th , and ^228Th in sediments showed that there was an excess of ^228Th over that supported by the parents ^282Th or ^228Ra in sediments in many regions. This excess ^228Th with a half-life of 1.91 years can be used for dating purpose over a time period of the order of a decade, so average sedimentary rates in the Yalujiang River Estuary, and in the Huanghe River Estuazy and its adjacent Laizhou Bay can be obtained from decreases in the excess ^228Th activity as a function of depth in sediment. 相似文献
94.
S. Zola R.H. Nelson H.V. Şenavcı T. Szymanski A. Kuźmicz M. Winiarski D. Jableka 《New Astronomy》2012,17(8):673-678
We present the results of the study of the contact binary system BO CVn. We have obtained physical parameters of the components based on combined analysis of new, multi-color light curves and spectroscopic mass ratio. This is the first time the latter has been determined for this object. We derived the contact configuration for the system with a very high filling factor of about 88%. We were able to reproduce the observed light curve, namely the flat bottom of the secondary minimum, only if a third light has been added into the list of free parameters. The resulting third light contribution is significant, about 20–24%, while the absolute parameters of components are: M1 = 1.16, M2 = 0.39, R1 = 1.62 and R2 = 1.00 (in solar units).The O-C diagram shows an upward parabola which, under the conservative mass transfer assumption, would correspond to a mass transfer rate of dM/dt = 6.3 × 10?8M⊙/yr, matter being transferred from the less massive component to the more massive one. No cyclic, short-period variations have been found in the O-C diagram (but longer-term variations remain a possibility). 相似文献
95.
We obtained estimates of the Johnson V absolute magnitudes (H) and slope parameters (G) for 583 main-belt and near-Earth asteroids observed at Ond?ejov and Table Mountain Observatory from 1978 to 2011. Uncertainties of the absolute magnitudes in our sample are <0.21 mag, with a median value of 0.10 mag. We compared the H data with absolute magnitude values given in the MPCORB, Pisa AstDyS and JPL Horizons orbit catalogs. We found that while the catalog absolute magnitudes for large asteroids are relatively good on average, showing only little biases smaller than 0.1 mag, there is a systematic offset of the catalog values for smaller asteroids that becomes prominent in a range of H greater than ~10 and is particularly big above H ~ 12. The mean (Hcatalog ? H) value is negative, i.e., the catalog H values are systematically too bright. This systematic negative offset of the catalog values reaches a maximum around H = 14 where the mean (Hcatalog ? H) is ?0.4 to ?0.5. We found also smaller correlations of the offset of the catalog H values with taxonomic types and with lightcurve amplitude, up to ~0.1 mag or less. We discuss a few possible observational causes for the observed correlations, but the reason for the large bias of the catalog absolute magnitudes peaking around H = 14 is unknown; we suspect that the problem lies in the magnitude estimates reported by asteroid surveys. With our photometric H and G data, we revised the preliminary WISE albedo estimates made by Masiero et al. (Masired, J.R. et al. [2011]. Astrophys. J. 741, 68–89) and Mainzer et al. (Mainzer, A. et al. [2011b]. Astrophys. J. 743, 156–172) for asteroids in our sample. We found that the mean geometric albedo of Tholen/Bus/DeMeo C/G/B/F/P/D types with sizes of 25–300 km is pV = 0.057 with the standard deviation (dispersion) of the sample of 0.013 and the mean albedo of S/A/L types with sizes 0.6–200 km is 0.197 with the standard deviation of the sample of 0.051. The standard errors of the mean albedos are 0.002 and 0.006, respectively; systematic observational or modeling errors can predominate over the quoted formal errors. There is apparent only a small, marginally significant difference of 0.031 ± 0.011 between the mean albedos of sub-samples of large and small (divided at diameter 25 km) S/A/L asteroids, with the smaller ones having a higher albedo. The difference will have to be confirmed and explained; we speculate that it may be either a real size dependence of surface properties of S type asteroids or a small size-dependent bias in the data (e.g., a bias towards higher albedos in the optically-selected sample of asteroids). A trend of the mean of the preliminary WISE albedo estimates increasing with asteroid size decreasing from D ~ 30 down to ~5 km (for S types) showed in Mainzer et al. (Mainzer, A. et al. [2011a]. Astrophys. J. 741, 90–114) appears to be mainly due to the systematic bias in the MPCORB absolute magnitudes that progressively increases with H in the corresponding range H = 10–14. 相似文献
96.
Zdeněk Řanda Jiří Mizera Jaroslav Frána Jan KuČEra 《Meteoritics & planetary science》2008,43(3):461-477
Abstract— Twenty‐three moldavites from a new locality, the Cheb Basin in Western Bohemia, were analyzed by instrumental neutron activation analysis for 45 major and trace elements. Detailed comparison of the Cheb Basin moldavites with moldavites from other substrewn fields in both major and trace element composition shows that the Cheb Basin is a separate substrewn field. The geochemical data obtained are discussed with respect to the source materials and processes leading to formation of moldavites. The data show that three groups of Cheb Basin moldavites exist. Ten samples of group 1 are characterized by the lowest content of Al, Fe, Na, and other elements representing phyllosilicate minerals, and by high Ca + Mg contents related probably to carbonates. They resemble the “poisonous green” moldavites, a subgroup of the Southern Bohemian moldavites. Seven samples of group 2 and 6 samples of group 3 are similar to typical moldavites of the Southern Bohemian substrewn field. These two groups differ from each other mainly in Al contents; with higher contents of Al and the elements associated with phyllosilicate minerals (namely Ba and Sr), group 3 also resembles the Moravian moldavites. Significant positive correlations between K, Ca, Mg, and Mn found in group 2 of the Cheb Basin moldavites and the enrichment in these elements observed generally in all moldavites, as well as other facts, e.g., high K/Na and K/Rb ratios and the reduced conditions during formation of moldavites, have been attributed to possible contribution to the moldavite source materials of the ash produced by burning of vegetation and soil organic matter present at the pre‐impact area. 相似文献
97.
Cheng-Yu Ku Chih-Yu Liu Yan Su Jing-En Xiao Chi-Chao Huang 《Environmental Earth Sciences》2017,76(16):570
This study investigates the transient modeling of regional rainfall-triggered shallow landslides in unsaturated soil using the Richards equation. To model shallow landslides within a distributed regional-scale framework, infinite slope stability analysis coupled with the hydrological model with consideration of the fluctuation of time-dependent pore water pressure and the soil–water characteristic curve proposed by van Genuchten was developed. The validity of the proposed model is established through several test problems by comparing the numerical results with the analytical solutions. A new procedure to set up wide-range shallow landslide analysis and to integrate regional distribution variations for input data such as geology, groundwater level, hydrogeological characteristics, and rainfall intensity and duration was presented. The results obtained demonstrate that the computed distribution of the safety factor is consistent with the distribution of actual landslides. In addition, the fluctuation of pore water pressure in unsaturated soil dominates the stability of landslides during typhoons accompanied by heavy rainfall. The findings observed in this study are a fundamental contribution to environmental effects for landslides in areas with higher occurrence and vulnerability to extreme precipitation. 相似文献
98.
Hong-Chun Li Teh-Lung Ku Dao-Xian Yuan Nai-Jung Wan Zhi-Bang Ma Ping-Zhong Zhang Miryam Bar-Matthews Avner Ayalon Zai-Hua Liu Mei-Liang Zhang Zhao-Yu Zhu Ruo-Mei Wang 《Applied Geochemistry》2007
A total of 117 water samples, including cave water, ground water, spring water and river water, collected from the monsoonal area of China have been analyzed for their H- and O-isotope composition. Overall, a δ18O–δD correlation is observed of δD = −4.45 + 6.6δ18O (R2 = 0.90) and a significant evaporation effect observed for the southern sites. Average δ18O and δD site values generally correspond to those of precipitation in nearby cities, with correlations of δD = 2.18 + 7.23δ18O (R2 = 0.95) for the sample sites and δD = 11.05 + 7.95δ18O (R2 = 0.95) for the cities. The effects of rainfall amount and temperature on precipitation δ18O were calculated using a simplified theoretical model derived from the Rayleigh distillation equation, which demonstrated that the sign of δ18Opvs. T correlation is dependent on precipitation intensity. The mean δ18O value of cave waters exhibit decreasing trends with increasing latitude and reveal a spatial pattern of positive correlation with annual mean temperature and precipitation, mainly reflecting isotopic fractionations in the moisture source traveling from the ocean side to the inland continent. This spatial pattern implies that the δ18O values recorded in the proxy climate records derived from speleothems might be influenced by shifts in monsoon boundary during the past, especially between glacial and interglacial intervals. 相似文献
99.
Xueyan Jiang Zhigang Yu Teh-Lung Ku Xinglun Kang Wei Wei Hongtao Chen 《Estuaries and Coasts》2007,30(6):919-926
The Yellow River (Huanghe) is the second largest river in China and is known for its high turbidity. It also has remarkably
high levels of dissolved uranium (U) concentrations (up to 38 nmol 1-1). To examine the mixing behavior of dissolved U between river water and seawater, surface water samples were collected along
a salinity gradient from the Yellow River plume during September 2004 and were measured for dissolved U concentration,234U:238U activity ratio, phosphate (PO4
3–), and suspended particulate matter. Laboratory experiments were also conducted to simulate the mixing process in the Yellow
River plume using unfiltered Yellow River water and filtered seawater. The results showed a nonconservative behavior for dissolved
U at salinities < 20 with an addition of U to the plume waters estimated at about 1.4 X 105 mol yr–1. A similarity between variations in dissolved U and PO4
3– with salinity was also found. There are two major mechanisms, desorption from suspended sediments and diffusion from interstitial
waters of bottom sediments, that may cause the elevated concentrations of dissolved U and PO4
3– in mid-salinity waters. Mixing experiments indicate that desorption seems more responsible for the elevated dissolved U concentrations,
whereas diffusion influences more the enrichment of PO4
3–. 相似文献
100.