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   158篇
  免费   28篇
  国内免费   13篇
测绘学   4篇
大气科学   34篇
地球物理   55篇
地质学   47篇
海洋学   19篇
天文学   2篇
综合类   10篇
自然地理   28篇
  2023年   4篇
  2022年   5篇
  2020年   8篇
  2019年   6篇
  2018年   8篇
  2017年   7篇
  2016年   5篇
  2015年   7篇
  2014年   6篇
  2013年   8篇
  2012年   11篇
  2011年   15篇
  2010年   11篇
  2009年   15篇
  2008年   5篇
  2007年   7篇
  2006年   7篇
  2005年   4篇
  2004年   7篇
  2003年   7篇
  2002年   3篇
  2001年   7篇
  2000年   1篇
  1999年   1篇
  1998年   4篇
  1997年   4篇
  1996年   3篇
  1995年   4篇
  1994年   1篇
  1993年   1篇
  1992年   5篇
  1990年   2篇
  1989年   2篇
  1988年   2篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1984年   2篇
  1982年   1篇
排序方式: 共有199条查询结果,搜索用时 140 毫秒
81.
82.
The temperature and salinity data obtained by the Iwate Fisheries Technology Center for the 25-year period from 1971 to 1995 were analyzed to clarify the seasonal variations in the sea off Sanriku, Japan. The variations of three typical waters found in this region, the Tsugaru Current water, the Oyashio water, and the Kuroshio water are discussed in terms, of a T-S scatter diagram referring to the water mass classification proposed by Hanawa and Mitsudera (1986). The mean temperature and salinity fields averaged for each month show clear seasonal variation. Distributions of the Tsugaru Current water and the Oyashio water can barely be distinguished in the fields deeper than 200 m since the Tsugaru Current has a shallow structure; however, the fields at 100 m depth indicate remarkable seasonal variation in the area of the Tsugaru Current. At 100 m depth, the temperature and salinity fronts between the Tsugaru Current water and the Oyashio water gradually disappear in January through April, appear again in May, then become clearest in September. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
83.
用塑料薄膜袋进行一级藻种培养的研究   总被引:1,自引:1,他引:1  
本文主要介绍用塑料薄膜袋代替1—2×1O~4mL细口瓶来进行饵料一级藻种培养,此法保证了扇贝育苗所需大量饵料的优质藻种,简单易行。 Ⅰ.材料与方法 Ⅰ.1.制袋的材料和方法 采用直径30cm,长度120cm的聚乙烯透明  相似文献   
84.
卢芳华 《极地研究》2016,28(4):523-531
北极在气候、资源、航道、科考等诸多领域对我国有着重要的现实和潜在价值,科考活动在资源争夺上的工具价值更是独一无二,同时,科考作为低敏感领域的活动也最容易开展合作。《联合国海洋法公约》和《斯匹次卑尔根群岛条约》是目前北极科考活动主要的法律规范。作为发展中大国,中国既有对北极科考的法律依据又有雄厚的科研实力。北极科考活动的拓展关涉中国在北极航道、渔业、投资等领域重要的国家利益,也有利于我国未来在北极事务中占有一席之地。因此,我国应进一步加大北极科考活动力度,参与北极科考活动法律规范的制定,进而提升我国在北极事务中的参与权和发言权。  相似文献   
85.
六十年前召开的第一届全国地层会议对我国的地层学、古生物学发展起了非常大的推动作用,带来了我国地层古生物学科发展的第一个黄金时期,为改革开放之后我国地层古生物学的辉煌发展打下了坚实的基础。这次会议上成立的全国地层委员会作为全国地层工作的组织、协调单位至今仍然在发挥着重要而且积极的作用。  相似文献   
86.
First Nations in British Columbia (BC), Canada, have historically been—and largely continue to be—excluded from colonial governments’ decision-making and management frameworks for fresh water. However, in light of recent legal and legislative changes, and also changes in water governance and policy, there is growing emphasis in scholarship and among legal, policy and advocacy communities on shifting water governance away from a centralized single authority towards an approach that is watershed-based, collaborative, and involves First Nations as central to decision-making processes. Drawing on community-based research, interviews with First Nations natural resource staff and community members, and document review, the paper analyzes the tensions in collaborative water governance, by identifying First Nations’ concerns within the current water governance system and exploring how a move towards collaborative watershed governance may serve to either address, or further entrench, these concerns. This paper concludes with recommendations for collaborative water governance frameworks which are specifically focused on British Columbia, but which have relevance to broader debates over Indigenous water governance.  相似文献   
87.
Acoustic radiation from a point driven, infinite, periodically ring-stiffened, laminated composite cylindrical shell submerged in flowing fluid is investigated theoretically. Both the effects of in-plane and out-of-plane vibrations of the ring-stiffeners and the effects of fluid convection on far field acoustic radiation behaviors are concerned. The equations of motion of the laminated composite cylindrical shell is presented on the basis of the first order shear deformation theory. Fourier transform and Poisson summation formula are used to transform the equations into a set of infinite algebraic equations expressed in the wavenumber domain. After truncation, the response of the laminated composite cylindrical shell is solved, and the stationary phase approximate is employed to find the expression for the far field sound pressure. Convergence analysis of the numerical solutions is conducted. The theoretical model and numerical method proposed in this paper are validated by comparison with those presented in available literature. Finally, numerical results are presented to demonstrate the effects of various parameters such as the size and spacing of the ring-stiffener, the thickness and the radius of the cylindrical shell, the lamination angle and the lamination scheme of the composite materials as well as the Mach number on the far field sound pressure.  相似文献   
88.
89.
《Climate Policy》2013,13(2-3):231-239
Abstract

Articles 4.8 and 4.9 of the United Nations Framework Convention on Climate Change (UNFCCC) and Article 3.14 of its Kyoto Protocol require parties to take measures to minimise the adverse effects of climate change on developing and least developed countries (LDCs). The Alliance of Small Island States (AOSIS) argue that this should mean assistance for capacity building to help them adapt to a changing climate. Articles 4.8 and 3.14 also require parties to take measures to minimise the impacts of emission reduction measures on energy exporting countries. The Organisation of Petroleum Exporting Countries (OPEC) countries argue that this should mean assistance to compensate for lost oil revenues. This paper explores the dimensions of the adverse effects/impacts issue. It explains how, in arguing that progress on Articles 4.8, 4.9 and 3.14 be equal to progress on the issue of assistance to compensate for lost oil revenues, OPEC countries obstruct progress on assistance to developing and LDCs for adaptation to climate change. This suggests that tacit G77/China support for OPEC's position may ultimately not be in their best interests. The paper discusses the outlook for the adverse effects/impacts of response measures issue.  相似文献   
90.
减缓和适应是应对气候变化的互补性策略,但在《联合国气候变化框架公约》(简称《公约》)的谈判中,适应在很长一段时期都处于减缓的从属地位。《公约》20多年的适应谈判进程可划为早期缓慢发展、科学和技术讨论、适应与减缓并重、增强适应行动和全面适应行动5个阶段,呈现出由无到有、重要性不断增强的特点。这一特点反映了全球对气候变化影响和适应重要性认识的不断深入及适应气候变化挑战的不断增强。未来适应谈判将聚焦于如何通过《公约》现有机制增强行动及如何增加适应资金以满足发展中国家的适应需求。  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