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991.
研究样品采自太平洋东部W2001-2站位(154°07'42"W,10°30'34"N,水深5102m),以无扰动多管采样方式采样.本文通过研究氯仿沥青"A"、有机质和有机分子与微量元素的关系,探讨了有机质在柱样形成中的作用.结果表明,大致以21-33cm和33-48cm为界线,呈现出系统的变化规律:正构烷烃呈单峰群分布,主碳峰为C25,碳优势指数(carbon preference index,CPI)为0.90-1.26,略显奇偶优势,反映出正构烷烃的母质除了少部分来自海洋菌藻类,主要来自洋底较深处软泥.低的姥鲛烷/植烷(Pe/Ph<0.81),反映了柱样的强还原环境性质.饱和烃/芳烃比值低,存在大量不饱和烃(非烃+沥青质为49.63%-59.66%),富含有利于早期成烃的特殊组分,并长期处于低演化阶段,以上特征均显示出样品的低成熟特点.研究还表明元素Ti和V与有机碳、氯仿沥青"A"呈正相关性;元素P、Mg和Mn与有机碳、氯仿沥青"A"呈明显负相关性,与非烃也有一定的相关性,这些提供了低成熟度条件下有机质的组成特点及其与化学元素作用的证据.  相似文献   
992.
本文以北碚城区为例,运用2004年和2007年两期高分辨率遥感影像数据资料,研究城区建设用地变化格局,结果表明:①建设用地类型之间转换力度较大,城区建设用地迅速扩张;②城区建设用地重心发生偏移。最后在引起变化的众多动力因子中,从经济发展、交通条件、人口增长和行政因素等方面进行分析,以期为城市规划、环境保护、社会经济协调发展等提供科学的决策依据。  相似文献   
993.
?о???1996??2005??????????52????С?????????????6????????????????????????????????????????????????????????????P???????NW????300??320???????У??????????????????????????????????????????????????????????????????????????????????仯?????????????????????????????????????NNW????????????總?????????????NWW????EW????  相似文献   
994.
Numerical flow and performance analysis of a water-jet axial flow pump   总被引:1,自引:0,他引:1  
The purpose of the present study is to investigate the performance and three-dimensional flow fields in a water-jet pump. TASCflow is employed to simulate the rotator-stator coupling flow field. A standard k-ε turbulence model combined with standard wall functions is used. In order to investigate the effect of a rear stator on flow fields, the flows in two water-jet pumps with and without a rear stator are studied. Computational fluid dynamics (CFD)-predicted overall performances are in good agreement with the experimental results. Then the flow fields, such as the pressure distribution on the blade surfaces, and the axial and tangential velocity distribution, especially the radial loading distribution, are investigated at different flow rates. In addition, the effects of a rear stator and different spacings between the rotor and the stator on the overall performance and the flow fields of the water-jet pump are also investigated.  相似文献   
995.
关皓  周林  王汉杰  景丽 《海洋学报》2008,30(4):30-38
利用LINUX操作系统下的进程通讯(IPC)技术将中尺度大气模式MM5(V3)与第三代海浪模式WW3进行双向耦合,建立考虑大气-海浪相互作用的风浪耦合模式,在耦合模式中引入3种海表粗糙度参数化方案,通过对一次热带气旋过程的模拟,研究大气-海浪相互作用对热带气旋系统的影响及耦合模式对海表粗糙度参数化方案的敏感性。结果表明:LINUX系统下的进程通讯技术可以方便有效地实现大气和海浪模式的双向耦合,模式运行稳定;耦合模式能够较好的模拟热带气旋的发展和演变过程及其影响下海浪场的分布和演变,模拟结果对海表粗糙度参数化方案较敏感;海浪的反馈作用同时影响了海气间的动力和热力作用过程,不同的海表粗糙度参数化方案下,海浪对两种作用过程不同的影响程度决定了其对气旋系统强度的影响。  相似文献   
996.
The scattering of water waves by bottom-mounted vertical circular cylinders is solved by using the null-field integral equations in conjunction with degenerate kernels and Fourier series to avoid calculating the Cauchy and Hadamard principal values. In the implementation, the null-field point can be exactly located on the real boundary owing to the introduction of degenerate kernels for fundamental solutions. An adaptive observer system of polar coordinates is considered to fully employ the properties of degenerate kernels. For the hypersingular equation, vector decomposition for the radial and tangential gradients is carefully considered. This method can be seen as a semi-analytical approach since errors attribute from the truncation of Fourier series. Neither hypersingularity in the Burton and Miller approach nor the CHIEF concept was required to deal with the problem of irregular frequencies. Five advantages of free of calculating principal value, well-posed algebraic system, convergence rate of exponential order, meshfree and elimination of boundary-layer effect, are achieved by using the present approach. Numerical results are given for the forces and free-surface elevation around the circular boundaries. Also, the near-trapped behavior arisen from the physical resonance is detected. A general-purpose program for water wave impinging several circular cylinders with arbitrary number, radii, and positions was developed. Several examples of water wave structure interaction by vertical circular cylinders were demonstrated to see the validity of the present formulation.  相似文献   
997.
The levels of 19 kinds of organochlorine pesticides (OCPs) in the aqueous phase, suspended particulate matter (SPM), pore water and sediments from Daliao River estuary of Liaodong Bay (Bohai Sea) in northeast China were investigated to evaluate their potential pollution risks. The total OCPs concentrations in the aqueous phase, SPM, pore water and sediments were 3.7–30.1 ng l−1, 4.6–52.6 ng l−1, 157–830 ng l−1 and 2.1–21.3 ng g−1 dry weight, respectively. The concentrations of OCPs, in the Daliao River estuary, are in the mid-range, as compared to those reported in other estuaries worldwide. The distribution of HCHs and DDTs were different indicating different contamination sources. Lindane is the main type of HCH and continuing use in northeast China of ‘pure’ HCH (lindane) rather than technical HCH accounts for the source. The ratios of (DDE + DDD)/DDT in the samples indicate no recent inputs of these chemicals to the estuary.  相似文献   
998.
Based on the sequence data of the nuclear ribosomal DNA internal transcribed spacer (ITS) 1, 5.8 S, and ITS 2, the molecular phylogeny was analyzed on Ulvaceae species collected from Qingdao coasts in summer of 2007, including 15 attached Ulva and Enteromorpha samples from 10 locations and 10 free-floating Enteromorpha samples from seven locations. The result supported the monophyly of all free-floating Enteromorpha samples, implying the unialgal composition of the free-floating Enteromorpha, and the attached Ulvaceae species from Qingdao coasts were grouped into other five clades, suggesting that they were not the biogeographic origin of the free-floating Enteromorpha in that season. Supported by NSFC (40506030); the Innovative Key Project of the Chinese Academy of Sciences (KZCX2-YW-209); Science & Technology Project of Qingdao City (06-2-2-12-JCH)  相似文献   
999.
????1992??11???2007??5?μ???????????????????????????仯???????????????1???????24~42???μ???????Я???????????ENSO?????2??SLA_2442?????????????????????????????????????????????????????????????????3?????????У????????????SLA_2442?????????·??????O???Σ??????????????,??γ????????λ??????9.86??N??8??S??????  相似文献   
1000.
Due to its rapid growth, the introduced mangrove species Sonneratia apetala from Bangladesh has been widely used in mangrove restoration in southeastern China since 1985. As an indigenous mangrove species in Hainan, China, Sonneratia caseolaris was also planted in Guangdong Province for afforestation purposes. Both species have developed well in their new habitats, but their ecophysiological differences with the native mangrove species have not been studied. In this study, leaf gas exchange, water and nitrogen use efficiencies of two Sonneratia species were compared with those of selected native mangrove species (Avicennia marina, Aegiceras corniculatum, Kandelia candel, and Excoecaria agallocha) in Hainan and Shenzhen. The introduced S. apetala maintained lower carbon assimilation rate (A) and photosynthetic nitrogen use efficiency (PNUE) than the indigenous S. caseolaris. In Shenzhen, the two introduced Sonneratia had comparable photosynthetic rates and water use efficiency (WUE) with the native mangrove species, except that PNUE in S. caseolaris was significantly higher than in the native mangrove species. The two Sonneratia species showed significant overlap in PNUE and long-term WUE. Photosynthetic parameters derived from leaf photosynthetic light–response curves and ACi curves also suggested lower carbon assimilation capacities for the introduced Sonneratia than for the native mangrove species in both study sites. The lower light compensation point (LCP) of two introduced Sonneratia in both study sites also indicated a better adaptation to a low light regime than the native mangrove species. The results of photosynthetic capacities indicated that the introduced mangrove species have little competitive advantage over local native mangrove species in their respective new habitats.  相似文献   
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