全文获取类型
收费全文 | 445篇 |
免费 | 47篇 |
国内免费 | 39篇 |
专业分类
测绘学 | 30篇 |
大气科学 | 66篇 |
地球物理 | 79篇 |
地质学 | 112篇 |
海洋学 | 135篇 |
天文学 | 15篇 |
综合类 | 18篇 |
自然地理 | 76篇 |
出版年
2023年 | 5篇 |
2022年 | 5篇 |
2021年 | 19篇 |
2020年 | 8篇 |
2019年 | 14篇 |
2018年 | 11篇 |
2017年 | 40篇 |
2016年 | 21篇 |
2015年 | 17篇 |
2014年 | 17篇 |
2013年 | 23篇 |
2012年 | 27篇 |
2011年 | 22篇 |
2010年 | 14篇 |
2009年 | 17篇 |
2008年 | 23篇 |
2007年 | 28篇 |
2006年 | 28篇 |
2005年 | 31篇 |
2004年 | 16篇 |
2003年 | 21篇 |
2002年 | 7篇 |
2001年 | 18篇 |
2000年 | 6篇 |
1999年 | 14篇 |
1998年 | 13篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1980年 | 1篇 |
排序方式: 共有531条查询结果,搜索用时 15 毫秒
1.
利用 12年的Lageos 1卫星激光测距资料 (1990 - 2 0 0 1)解算得到了地球定向参数 (EOP) ,将该序列的结果与同期的EOP(IERS)C0 4进行比较 ,其外符精度为 :极移XP— 0 .4 0mas,YP— 0 .4 2mas ,日长变化Dr— 0 .0 35ms。 相似文献
2.
A code of practice for ocean mining has been developed by the International Marine Minerals Society. The code provides general guiding Principles for development of marine mineral resources and delineates Operating Guidelines for application, as appropriate, at specific mining sites. In total 11 operating guidelines are provided to serve as benchmarks for industry and targets for regulatory agencies and other stakeholders. They include the following commitments: •To sustainable development, •To environmentally responsible corporate ethics, •To the development of effective community partnership, •To implementation of environmental risk management, •To the integration of environmental management into all phases of development, •To the establishment of corporate environmental performance targets, •To timely environmental improvements and upgrading, •To responsible rehabilitation of operations sites and decommissioning of facilities, and •To accurate and timely, reporting and documentation, archiving, and performance review. 相似文献
3.
4.
迎接寒武系全球年代地层的新划分——2004年版“国际地层表”述评 总被引:9,自引:4,他引:9
评述了国际地层委员会最新公布的2 0 0 4年版“国际地层表”的寒武系部分,包括它的底界全球层型和点位的确定和存在的问题、寒武系当前的再划分情况、芙蓉统和排碧阶及其底界全球层型剖面和点位、寒武系的时代跨度。介绍了全球寒武系年代地层的研究方向和正在表决中的全球寒武系最新划分方案。讨论了与我国寒武系年代地层的划分和建立地方性、区域性年代地层系统的相关问题 相似文献
5.
“国际地层表”与GSSP 总被引:11,自引:2,他引:11
近年来,“国际地层表”不断被国际地层委员会更新,用GSSP来定义年代地层单位而建立起来的“国际地层表”,使得大家在叙述地质历史时有一种共同的语言、有一个全球性的标准。在显生宇的96个阶(统)中已有4 6个阶(统)确立了GGSP,其余的有望在2 0 0 8年全部确立。我国已取得了4枚金钉子,即将取得3枚,还有可能再获得4—6枚。根据区域特点,我国已编制了“中国区域年代地层(地质年代)表”并正在开展区域性建阶工作 相似文献
6.
Becky Mansfield 《Geoforum》2003,34(3):329-342
This paper addresses the cultural economy of nature and the material culture of economic practice. Attending to ways that cultural notions about the biophysical world play key roles in political economic conflicts, discussion centers on two recent debates involving the cultural economy of seafood production and trade. The first debate is over whether the label “catfish” should include catfish imported from Vietnam into the United States; the second deals with whether fish and shellfish should be eligible to be certified “organic” under new US regulations. Analysis reveals that the key dynamic in these debates is not necessarily how people think about “nature”, but instead is how people make distinctions about the world. Rather than focusing on what is natural or not, key actors make distinctions among both organisms and environments. The ways that different groups define and enclose the biophysical world works to distinguish places as either appropriate or not for certain kinds of production activities. The overall argument is that significance and meaning of the biophysical become implicated in economic geographies by making distinctions about the world that then become important for how economic activity can work. As such, cultural economic approaches should attend to the ways that the biophysical is involved in relations such as competition and international trade, while nature-society approaches should shift focus from Nature to specific aspects of the biophysical world. 相似文献
7.
建设中老缅泰国际合作开发区营造景洪市立体开放口岸系统 总被引:1,自引:0,他引:1
本文论述了中老缅泰国际合作开发区建设是澜沧江—湄公河流域开发的优先启动区,是南南合作的新模式,对推动中南半岛次区域合作发挥着先导功能。景洪作为中国西南边境城市,在未来次区域合作中将升格为枢纽城市之一,因此,其开放度要不断扩大,在已具有的国家一类水运口岸基础上,要继续营造国家一类航空口岸、公路口岸,并在跨世纪建造昆明—曼谷铁路时,设置国家一类铁路口岸,同时在中缅240界桩两侧开辟新型的边境贸易旅游区,构筑景洪市全方位立体型开放系统。 相似文献
8.
This short note reviews our thinking on how IGGOS can best achieve a high status within the set of global monitoring programmes. If such a high status can be obtained, then the importance of geodetic networks and services will be recognized more widely, and their activities will consequently be better resourced in the long term. One particular aspect concerns how IGGOS can complement the roles of the various IGOS partners within global monitoring. The different ways in which IGGOS can contribute to IGOS are outlined. 相似文献
9.
Michael Pearlman Carey Noll Peter Dunn Julie Horvath Van Husson Paul Stevens Mark Torrence Hoai Vo Scott Wetzel 《Journal of Geodynamics》2005,40(4-5):470
The International Laser Ranging Service (ILRS) was established in September 1998 as a service within the IAG to support programs in geodetic, geophysical, and lunar research activities and to provide data products to the International Earth Rotation Service (IERS) in support of its prime objectives. Now in operation for 5 years, the ILRS develops: (1) the standards and specifications necessary for product consistency and (2) the priorities and tracking strategies required to maximize network efficiency. The service collects, merges, analyzes, archives and distributes satellite and lunar laser ranging data to satisfy a variety of scientific, engineering, and operational needs and encourages the application of new technologies to enhance the quality, quantity, and cost effectiveness of its data products. The ILRS works with: (1) the global network to improve station performance; (2) new satellite missions in the design and building of retroreflector targets to maximize data quality and quantity and (3) science programs to optimize scientific data yield. The ILRS Central Bureau maintains a comprehensive web site as the primary vehicle for the distribution of information within the ILRS community. The site, which can be accessed at: http://ilrs.gsfc.nasa.gov is also available at mirrored sites at the Communications Research Laboratory (CRL) in Tokyo and the European Data Center (EDC) in Munich.During the last 2 years, the ILRS has addressed very important challenges: (1) data from the field stations are now submitted hourly and made available immediately through the data centers for access by the user community; (2) tracking on low satellites has been significantly improved through the sub-daily issue of predictions, drag functions, and the real-time exchange of time biases; (3) analysis products are now submitted in SINEX format for compatibility with the other space geodesy techniques; (4) the Analysis Working Group is heavily engaged in Pilot Projects as it works toward an ILRS “standard” global solution and (5) SLR has significantly increased its participation in the International Terrestrial Reference Frame (ITRF) activity, which is important to the success of IGGOS. 相似文献
10.
The International GPS Service tracking network: Enabling diverse studies and projects through international cooperation 总被引:2,自引:0,他引:2
The International GPS Service (IGS), formulated beginning in 1989 and formalized in 1994, was founded on the collaborative operation of approximately 30 permanent GPS stations to benefit global geodynamics. The same cooperative principles, today applied to a network of over 300 stations, still serve to maximize global benefit without unnecessary duplication of investment in global infrastructure. The scope of applications of the dataset has grown to include atmospheric, oceanographic, subdaily, and low-earth orbiter activities through working groups and pilot projects fostered within the IGS in the now traditional IGS spirit of collaboration. These activities and the IGS infrastructure are viewed as critical elements to the Global Geodetic Observing System. This presentation will review the present nature of the IGS tracking network and its ability to support new applications. 相似文献