珊瑚礁连通性研究进展     

吴瑞 《湿地科学与管理》2016,(1):53-57

综述了国外近20 a珊瑚礁连通性的研究简史,总结了珊瑚礁连通性研究的方法,阐述了"珊瑚礁连通性"的研究对珊瑚礁生态系统管理的重要意义。中国的珊瑚礁连通性研究刚起步,离国外还有很大差距,今后应加强珊瑚幼虫扩散路径、珊瑚群体内(群体间)遗传分化、遗传距离、基因流的研究,对我国海域珊瑚幼虫扩散的走廊加以保护。  相似文献   

长岛县海洋产业结构优化研究          下载免费PDF全文

王芳  王刚  刘冲  纪灵 《海洋开发与管理》2016,33(3):20-24

21世纪是海洋的世纪,科学利用海洋资源、发展海洋经济是实现人类社会可持续发展的重要途径。海岛地区,要在新一轮竞争中抢占发展先机、实现新的跨越,必须加快产业结构调整,推动产业转型提质增效。对此,以长岛为例,对海洋产业结构优化进行了专题研究。  相似文献   

Simulation of quasi-linear mesoscale convective systems in northern China: Lightning activities and storm structure   总被引：1，自引：0，他引：1  

Wanli Li  Xiushu Qie  Shenming Fu  Debin Su  Yonghai Shen 《大气科学进展》2016,33(1):85-100

Two intense quasi-linear mesoscale convective systems(QLMCSs) in northern China were simulated using the WRF(Weather Research and Forecasting) model and the 3D-Var(three-dimensional variational) analysis system of the ARPS(Advanced Regional Prediction System) model.A new method in which the lightning density is calculated using both the precipitation and non-precipitation ice mass was developed to reveal the relationship between the lightning activities and QLMCS structures.Results indicate that,compared with calculating the results using two previous methods,the lightning density calculated using the new method presented in this study is in better accordance with observations.Based on the calculated lightning densities using the new method,it was found that most lightning activity was initiated on the right side and at the front of the QLMCSs,where the surface wind field converged intensely.The CAPE was much stronger ahead of the southeastward progressing QLMCS than to the back it,and their lightning events mainly occurred in regions with a large gradient of CAPE.Comparisons between lightning and non-lightning regions indicated that lightning regions featured more intense ascending motion than non-lightning regions;the vertical ranges of maximum reflectivity between lightning and non-lightning regions were very different;and the ice mixing ratio featured no significant differences between the lightning and non-lightning regions.  相似文献   

对数周期偶极子天线的设计、制造和测试     

耿立红 《天文研究与技术》1997,(1)

文中所作的主要工作是为云南天文台十米抛物面设计、制造一付好的对数周期偶极子天线（ＬＰＤＡ）作馈源。工作有：（１）设计一对交叉的ＬＰ－ＤＡ；（２）分析ＬＰＤＡ特性；（３）估算抛物面的电特性；（４）讨论线极化向园极化转换的问题；（５）天线测量。ＬＰＤＡ的测量结果比较满意。该天线的方向图、平均输入阻抗、三分贝和十分贝波瓣宽度都在从０．５－１．５ＧＨｚ的频率范围内比较一致和稳定，变化很小。天线理论上的许多成就都是与数子计算机有关的。在文中，我们充分利用了计算机的功能来设计天线，分析天线特性，并从测量所得的所有数据文件中计算天线的参数。所编ＦＯＲＴＲＡＮ程序使这一切工作变得容易。最后，我们还讨论了用功率合成器实现线极化向园极化转换的各种情况  相似文献   

从窗口看云南天文台     

谭徽松 《天文研究与技术》1997,(3)

简要总结了云南天文台２０年来的科研工作及人才培养情况，并对未来的发展提出了设想。  相似文献   

Models of the formation of the solar nebula     

Patrick Cassen  Audrey Summers 《Icarus》1983,53(1):26-40

Models of the collapse of a protostellar cloud and the formation of the solar nebula reveal that the size of the nebula produced will be the larger of $\text{R}{}_{\mathrm{<mtext>CF</mtext>}}\text{≡ J}{}^2\text{/k}{}^2\text{GM}{}^3\text{and}\text{R}{}_{\mathrm{<mtext>V</mtext>}}\text{≡ (GMv/2c}{}_{\mathrm{<mtext>c</mtext>}}{}^3\text{)}\text{1}\text{2}$ (where J, M, and c_s are the total angular momentum, total mass, and sound speed of the protosetellar material; G is the gravitational constant; k is a number of order unity; and v is the effective viscosity in the nebula). From this result it can be deduced that low-mass nebulas are produced if P ≡ (R_V/R_CF)² ? 1; “massive” nebulas result if P ? 1. Gravitational instabilities are expected to be important for the evolution of P ? 1 nebulas. The value of J distinguishes most current models of the solar nebula, since P ∝ J^?4. Analytic expressions for the surface density, nebular mass flux, and photospheric temperature distributions during the formation stage are presented for some simple models that illustrate the general properties of growing protostellar disks. It does not yet seem possible to rule out either P ? 1 or P < 1 for the solar nebula, but observed or possible heterogeneities in composition and angular-momentum orientation favor P < 1 models.  相似文献   

东川泥石流站开放以来的回顾与展望     

杜榕桓  康志成 《山地学报》1991,(3)

本文扼要介绍了中国科学院东川泥石流观测研究站对外开放三年来,在泥石流观测试验研究和防灾减灾工作中的新进展,同时也简述了站设基金课题、国家基金课题和中外合作交流项目的进展情况,并对今后的观测研究工作提出了展望和建议。  相似文献   

云南省怒江傈僳族自治州经济发展战略研究     

怒江州发展战略研究课题组 《云南地理环境研究》1989,1(1):35-43

怒江傈僳族自治州是云南省最贫困的民族自治州。本文在认真分析、正确认识州情和改革开放形势的前提下,提出经济发展的指导思想和资源开发脱贫型的战略模式,制定了战略目标、战略步骤和战略重点。在产业结构方面,确定以铅锌为主的有色金属工业,以大理石为主的建材工业,以林副产品为主的生物资源综合开发作为三大主导产业。为保证战略目标的实现,提出重视科学技术和教育事业;改善交通、解决能源、搞活流通:绝不放松粮食生产,慎重解决人口问题;高度重视水土保持,维持生态平衡;采取特殊政策和灵活措施等。  相似文献   

Microplastics as contaminants in the marine environment: a review   总被引：15，自引：0，他引：15  

Cole M  Lindeque P  Halsband C  Galloway TS 《Marine pollution bulletin》2011,62(12):2588-2597

Since the mass production of plastics began in the 1940s, microplastic contamination of the marine environment has been a growing problem. Here, a review of the literature has been conducted with the following objectives: (1) to summarise the properties, nomenclature and sources of microplastics; (2) to discuss the routes by which microplastics enter the marine environment; (3) to evaluate the methods by which microplastics are detected in the marine environment; (4) to assess spatial and temporal trends of microplastic abundance; and (5) to discuss the environmental impact of microplastics. Microplastics are both abundant and widespread within the marine environment, found in their highest concentrations along coastlines and within mid-ocean gyres. Ingestion of microplastics has been demonstrated in a range of marine organisms, a process which may facilitate the transfer of chemical additives or hydrophobic waterborne pollutants to biota. We conclude by highlighting key future research areas for scientists and policymakers.  相似文献   

美国内政部四轮战略规划的发展趋势及特点分析     

刘丽  陈丽萍  王威 《国土资源情报》2014,(9):6-13

美国内政部的战略规划是该部施政纲领的集中体现。四轮战略规划的目标从2003年强调资源保护、利用与休闲娱乐的平衡,到2007年增加全球经济、环境、政治和其他因素对内政部战略规划的影响,直至2014年强调资源的娱乐、人文观赏价值,并重视培养下一代的管理责任。内政部战略定位逐渐清晰。资源保护、经济发展、休闲娱乐的相对关系发生变化,从强调三者平衡到强调资源的休闲、文化等景观价值。  相似文献