首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   16篇
  免费   3篇
测绘学   2篇
大气科学   1篇
地球物理   3篇
地质学   3篇
海洋学   10篇
  2019年   1篇
  2017年   2篇
  2016年   1篇
  2015年   1篇
  2014年   1篇
  2012年   2篇
  2010年   1篇
  2008年   2篇
  2007年   2篇
  2005年   1篇
  2004年   2篇
  1998年   1篇
  1993年   1篇
  1991年   1篇
排序方式: 共有19条查询结果,搜索用时 15 毫秒
1.
通过对水库中12个围隔两次取样的叶绿素a浓度(单位:μg/L)、化学耗氧量(单位:mg·O_2/L)和塞克透明度(单位:m)的实验数据分析,求得如下回归方程: (1)[Chla]=17.60·[SD]~(-1·86) r=-0.87 (2)[Chla]=-28.85+7.32·[COD] r=0.89 (3)[COD]=6.88·[SD]~(-0·68) r=0.91本文还对这些结果进行了讨论。  相似文献   
2.
历经10余年的发展,采掘业透明倡议已经发生了巨大变化,西方发达国家开始积极介入,主动宣布试点或计划实施。形势的变化要求我国及时调整以往所持立场。本文简要介绍了全球采掘业透明倡议的组织架构及运作、实施现状,深入分析了各利益相关方的动机,对其未来发展加以研判,并结合我国涉及采掘业透明倡议的情况,提出了新形势下我国短期内不宜实施,但须及时调整立场;鼓励金融机构和企业介入EITI和其他反腐败倡议;政府应考虑成为EITI的正式支持国。  相似文献   
3.
随着海洋探测的不断发展,海水透明度作为海水光学性质的一个重要参量,也越来越受到人们的关注。文章对比分析了4种海水透明度现场测量方法:透明度盘法~([1])、光纤式高光谱剖面测量法~([2])、激光衰减测量法~([3])和基于双光路原理的海水IOPs高光谱测量法~([4]),主要分析了4种方法的测量原理,对比各自的优缺点,并提出了海水透明度测量未来发展设想。  相似文献   
4.
流体包裹体是古地质流体的唯一直接记录,为反演地质过程涉及的物理化学条件等提供了最为重要的证据。流体包裹体是研究热液矿床成矿流体最有利手段,常规的测试对象为透明的脉石矿物,而矿石矿物中的流体包裹体更为直接、准确地记录了成矿流体信息。大多数矿石矿物在显微镜透射光下不透明,其捕获的流体包裹体研究需要使用配备有红外成像系统的显微镜进行。近20 年来,不透明矿物流体包裹体红外显微测温研究获得了长足的进展,但其中仍有一些问题尚未解决,制约了该方法的应用;同时,国内该研究领域正处在起步阶段,多个实验室已安装了红外测试仪器,但尚未开展系统的研究工作。因此,需要对该研究领域进行综述,探讨存在的问题,以促进该研究方法的发展。本文首先介绍了红外显微镜仪器工作原理及样品制备注意事项,阐述了影响不透明矿物红外透明度的因素,讨论了红外显微测温研究中的主要问题和难点,并针对测温过程中相变观察困难、红外光可能影响测温结果等问题提出可行的解决方案,最后论述了红外显微测温系统在矿床学领域的应用前景。  相似文献   
5.
矫晓阳 《海洋科学》1993,17(4):65-67
1991年6月20日~9月11日,于大连市营城子镇东小磨对虾养殖场3号虾池采水样,固定后,检测浮游植物数量,同时测定透明度和对虾体长。实验结果见图1、图2,表1。结果表明,浮游植物密度、池水透明度和对虾体长增长速率三者之间有着密切的相互关系。  相似文献   
6.
Fairtrade was founded to alleviate poverty and economic injustice through a market-based form of solidarity exchange. Yet with the increasing participation of transnational food corporations in Fairtrade sourcing, new questions are emerging on the extent to which the model offers an alternative to the inimical tendencies of neoliberalism. Drawing on a qualitative research project of Kenyan Fairtrade tea, this paper examines how the process of corporate mainstreaming influences the structure and outcomes of Fairtrade, and specifically the challenges it poses for the realization of Fairtrade’s development aspirations. It argues firstly that whilst tea producers have experienced tangible benefits from Fairtrade’s social premium, these development ‘gifts’ have been conferred through processes marked less by collaboration and consent than by patronage and exclusion. These contradictions are often glossed by the symbolic force of Fairtrade’s key tenets - empowerment, participation, and justice - which simultaneously serve to neutralize critique and mystify the functions that Fairtrade performs for the political economy of development and neoliberalism. Second, building on recent critiques of corporate social responsibility, the paper explores how certain neoliberal rationalities are emboldened through Fairtrade, as a process of mainstreaming installs new metrics of governance (standards, certification, participation) that are at once moral and technocratic, voluntary and coercive, and inclusionary and marginalizing. The paper concludes that these technologies have divested exchange of mutuality, as the totemic features of neoliberal regulation - standards, procedures and protocols - increasingly render north south partnerships ever more virtual and depoliticized.  相似文献   
7.
研究菲律宾海透明度的变化规律,对国民经济和军事活动都有重要意义。以往由于缺乏资料,研究文献较少。本文根据国内外的有关资料,对菲律宾海的透明度特征进行了分析与研究,较详细地阐明了它的变化特点和规律。  相似文献   
8.
The International Seabed Authority (ISA) regulates the activities related with the exploration and exploitation of seabed mineral resources in the Area, which are considered as the "common heritage of mankind" under the United Nations Convention on the Law of the Sea. The ISA has also the mandate to ensure the protection of the marine environment. The development of good practices for the annual reporting and data submission by Contractors is crucial for the ISA to comply with the sustainable development of the mineral marine resources. In 2015, the ISA issued a new template for reporting on exploration activities, which includes the definition of the format for all geophysical, geological and environmental data to be collected and analysed during exploration. The availability of reliable data contributes to improve the assessment of the ISA on the activities in the Area while promoting transparency, which is considered as a major principle of industry best practices.  相似文献   
9.
The Gru?a Reservoir (located at 238…269 m a. s. l., volume 64.6 · 106 m3, surface 934 ha, drainage area 318 km2, max. depth 31 m, mean theoretical retention time 22 months) was investigated during the years 1996 to 2001. The obtained values of trophic state parameters (9…200 μg L?1 total phosphorus, 3…99 μg L?1 chlorophyll‐a, and 0.5…2 m transparency) indicate that water of the Gru?a Reservoir is eutrophic according to three types of classification: Carlson, OECD, and Jones and Lee. It was noticed that values of average biomass abundance are large in the Gru?a Reservoir, and they could indicate a richer trophic state. When these indices are cited in connection with parameters of the trophic state, it is apparent that the Gru?a Reservoir can be classified as a eutrophic water on the basis of total phosphorus content of chlorophyll‐a and hypertrophic water with respect to transparency.  相似文献   
10.
The simulation of the passage from the lithosphere through the atmosphere to the ionosphere of acoustic waves produced by seismic eruption or explosion shows that there is an acoustic coupling among these layers. This in turn is the cause of change in the transparency of the ionosphere for cosmic radio waves. Underground displacements produce Very Low (VLF) and Extremely Low Frequency (ELF) acoustic waves. In their passage through the lithosphere, the VLF wave is subject to nonlinearity that leads to frequency down-conversion, namely, increasing the ELF acoustic component at the Earth's surface. In turn, the nonlinear propagation of ELF acoustic wave in the atmosphere and the ionosphere leads to the emergence of ultra low frequency (ULF) acoustic waves in the ionosphere. An ultra low frequency acoustic wave (ULF) brings influence into the density of F-layer of the ionosphere and causes the transparency change of the ionosphere for cosmic radio waves.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号