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821.
???????GPS??TEC???????VTEC???????????15?????????????????ο????????????????????VTEC???? 2006??12??26??????????????7.2???????2008??5??12????8????????????????????????????8???????????????????????????????????????????????????????????????????VTEC????????????????????????????????VTEC??????????????????????????????????????????????????????  相似文献   
822.
In order to reveal transpiration rates of wetland plants and its relationships to micro- meterological factors in a mountain valley wetland, relative humidity, air temperature, leaf temperature, soil temperature, photo flux density and transpiration rates were measured once two hours in a Carex meyeriana wetland of the Changbai Mountain valley in dry (July) and wet (September) of 2003, respectively. Results showed that the tendency of "decreasing after increasing" was obvious in wet season. However, a relatively stable trend was observed for the transpiration in dry season.. Generally, the photon flux density of Carex meyeriana was higher in wet season than that in dry season. However, the variabilities of leaf temperature, air temperature and relative humidity were similar in both seasons. Higher transpiration rates of Carex meyeriana leaves were observed in July (varied from 40 to 150 mol.m^-2.s^-1) compared to those (varied from 7 to 14 mol.m^-2.s^-1) in September. Transpiration rates were significantly correlated with air temperature (P〈0.01), leaf temperature (P〈0.01), and wind speed (P〈0.05), but correlationship between relative humidity and photo flux density was not significant (P〈0.05).  相似文献   
823.
针对震后被倒塌建筑物或滑坡埋压的被困人员进行快速定位问题,在阅读大量相关文献的基础上,以无人机遥感、地理信息空间和三维质心定位技术为基础,采用无线信号RSSI测距模型,配合影像范围内基准影像数据辅助定位,构建震后基于无人机快速三维定位被困人员模型.以红河县城区作为研究区,对城区内特定人员进行三维定位,结果表明该模型定位...  相似文献   
824.
Spartina alterniflora Loisel., an extensively invasive species on the Chinese coast, is a focus of increasing management concern due to its high expansion rate in estuaries and tidal zone, and the significant damage it causes to native ecosystems. In order to understand the processes and mechanisms of invasion of S. alterniflora in China, the impact of three sediment types (sand, sand–loam mixture and loam) and five buried patterns (unburied, 50% burial of initial plant height, 75% burial of initial plant height, complete burial and repeated burial) on the growth of seedlings or ramets was investigated. Results showed that each of the three factors (sediment types, burial pattern and plant materials) and interactions between/among them, significantly affected height and clonal growth, and biomass accumulation and allocation. Plant height, total biomass and number of new vegetative propagules significantly increased with progressive burial treatments. However, the complete burial treatment resulted in the death of all plant materials, and the maximum values of three parameters were found in the 50% burial or repeated burial treatments. Plant responses were determined by the instantaneous thickness of sediment of each time burial rather than by the total quantity of repeated burial. The growth of S. alterniflora was not shown to be dependent on specific types of sediment in sedimentation environment. In contrast to the unburied control, the proportion of primary tillers produced directly from initial individuals and the ratio between the aboveground and belowground biomass were greater under burial treatments. Seedlings produced more new vegetative propagules than vegetative offspring in all experimental treatments, and the former were apt to produce ramets from rhizomes rather than primary tillers. It is concluded that under various sedimentation environments, the clonal spread efficiency of seedlings was higher than that of vegetative offspring, and there is a positive feedback relationship between sedimentation and the growth of S. alterniflora. Thus, moderate sedimentation may stimulate the invasion of exotic species, S. alterniflora in coastal China.  相似文献   
825.
Preparation of Fe^2+ chelate of fish protein hydrolysate (Fe-FPH) obtained from low value fish proteins was introduced and its bioactivity was studied by compound enzymolysis. The optimum conditions for hydrolysate chelating Fe^2+ are DH (degree of hydrolysis) at 5%, pH 7.0, 20℃ and 15 min chelating time for FM (material not being defatted). Four types of Fe-FPH including CA (deposit after chelating), CB (deposit in 50% of absolute ethanol solution), CC (suspended deposit in 80% of absolute ethanol solution), and CD (bottom deposit in 80% of absolute ethanol solution) were fractionated with absolute ethanol from FM. Structural analysis through infra-red spectrum revealed that Fe^2+ was combined strongly with amino-group and carboxyl-group in each chelate and each Fe^2+ could form two five-member ring structures. All of the four chelates were shown more significant antioxidative activity and can be used as natural hydrophobic and hydrophilic antioxidant. Among all the chelates, the CB possesses the most effective antioxidative activity at 92% as high as that of a-tocopherol. Among all Fe-FPHs, only CD showed the most effective antibacterial activity against Escherichia coli, Staphylococcus aureus, Salmonella typhi, and Bacillus subtilis and can be used as natural antibacterial. It provides a more effective way for utilization of low value fish proteins and key information of Fe-FPH as additive in food industry.  相似文献   
826.
Duetoregionalhydrogeologicandclimaticconditions,inthewesternSongnenPlain,themostdistinctcharacteristicofwaterenvironmentinlimnicwetlandsisthatmanywaterbodieshavehighsaltcontentsandpHvalues,andsomelimnicwetlandsbelongtosaltmarshes.Thelimnicwetlandsofthisregionarespecialnaturecomplex.Itisimportantfortheutilizationofwetlandresourcesandtheintegrateddevelopmentofsaline-alkalinesoiltostudychemicalcharacteristicsofwaterenvironmentinthisregion.1NATURALENVIRONMENTCHARACTERISTICSOFTHEWE…  相似文献   
827.
福建沿岸地区红树林的种类与分布   总被引:11,自引:0,他引:11  
于1998年11月至1999年1月对福建沿岸地区的红树林进行了调查,就福建红树林的种类组成、面积、分布情况、人工造林情况进行了论述,并就制约福建发展红树林的因素及解决方法提出了一些建议。  相似文献   
828.
三维潮流和潮流输沙问题的一种混合数值模拟及其应用   总被引:5,自引:0,他引:5  
应用一种平面迎风有限元与垂向隐式有限差分相结合的数值计算方法建立了三维潮流和潮流输沙数学模型,并分别与相应的理论公式进行了对比验证.将建立的模型对广西廉州湾水域进行了计算,与实测资料的对比分析表明模型的计算结果符合实际.  相似文献   
829.
In this empirical study, we compare high-resolution observations obtained with the 65-cm vacuum reflector at Big Bear Solar Observatory (BBSO) in 2005 and with the Dunn Solar Telescope (DST) at the National Solar Observatory/Sacramento Peak (NSO/SP) in 2006. We measure the correction of the high-order adaptive optics (AO) systems across the field of view (FOV) using the spectral ratio technique, which is commonly employed in speckle masking imaging, and differential image motion measurements. The AO correction is typically much larger (10′′ to 25′′) than the isoplanatic angle and can be described by a radially symmetric function with a central core and extended wings. The full-width at half-maximum (FWHM) of the core represents a measure of the AO correction. The average FWHM values for BBSO and NSO/SP are 23.5′′ and 18.2′′, respectively. The extended wings of the function show that the AO systems still contribute to an improved speckle reconstruction at the periphery of the 80′′×80′′ FOV. The major differences in the level of AO correction between BBSO and NSO/SP can be explained by different contributions of ground-layer- and free-atmosphere-dominated seeing, as well as different FOVs of the wavefront sensors. In addition, we find an anisotropic spectral ratio in sunspot penumbrae caused by the quasi-one-dimensional nature of penumbral filaments, which introduces a significant error in the estimation of the Fourier amplitudes during the image restoration process.  相似文献   
830.
Heavy metals pollution in Jiaozhou Bay was studied inRuditapes. philippinarum, a bioindicator of seawater pollution. Heavy metals in soda industry wastes “white mud” were also studied. Comparison of microwave digestion method with general digestion method revealed that microwave digestion is superior to general digestion in precision, recovery, digestion speed and efficiency, etc. Cd concentration in HongdaoR. philippinarum samples exceeded the national standard by 0.046 mg/kg, that of Yinghai sample by 0.02 mg/kg, and that of Hongshiya sample by 0.22 mg/kg. Sample Pb concentration in Hongshiya was found to exceed the national standard by 0.02 mg/kg. However the heavy metals concentration inR. philippinarum near the Qingdao Alkaline Factory was complied with the standard. This was proved byPenaeus chinensis culture experiment. Therefore, the possible contamination source may come from other land areas. This study is supported by Project 973 (NO.2002CB 412402), and key project of the Chinese Academy of Sciences (Grant NO.KJCX315W-215).  相似文献   
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