全文获取类型
收费全文 | 485篇 |
免费 | 37篇 |
国内免费 | 20篇 |
专业分类
测绘学 | 21篇 |
大气科学 | 40篇 |
地球物理 | 156篇 |
地质学 | 196篇 |
海洋学 | 57篇 |
天文学 | 23篇 |
综合类 | 7篇 |
自然地理 | 42篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 29篇 |
2020年 | 24篇 |
2019年 | 24篇 |
2018年 | 27篇 |
2017年 | 22篇 |
2016年 | 24篇 |
2015年 | 10篇 |
2014年 | 22篇 |
2013年 | 38篇 |
2012年 | 23篇 |
2011年 | 29篇 |
2010年 | 10篇 |
2009年 | 25篇 |
2008年 | 20篇 |
2007年 | 14篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 16篇 |
2003年 | 19篇 |
2002年 | 32篇 |
2001年 | 22篇 |
2000年 | 15篇 |
1999年 | 11篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1954年 | 1篇 |
1953年 | 1篇 |
排序方式: 共有542条查询结果,搜索用时 15 毫秒
1.
N. Mihalopoulos J. P. Putaud B. C. Nguyen S. Belviso 《Journal of Atmospheric Chemistry》1991,13(1):73-82
Measurements of the concentrations of carbonyl sulfide (COS) in the marine atmosphere were made over a period of two years in the southern Indian Ocean (Amsterdam Island, 37°50 S–77°31 E; March 1987–February 1988 and April 1989–February 1990). The mean atmospheric COS concentration for the whole period was 475±48 pptv (n=544). Atmospheric COS concentrations show no significant seasonal variation with a summer to winter ratio of 1.05. Taking into account the observed variability of the atmospheric COS concentration (10%), a value of 1.4 yr is estimated as a lower limit for the atmospheric COS lifetime. A comparison of the COS data at Amsterdam Island with those obtained in the Southern Hemisphere in the past 12 yr does not reveal any significant trend in the tropospheric background COS mixing ratio. 相似文献
2.
Controlling geological and hydrogeological processes in an arsenic contaminated aquifer on the Red River flood plain,Vietnam 总被引:1,自引:0,他引:1
3.
Total dissolved selenium and selenium species have been measured in the Rhône river delta and the Gulf of Lions within the framework of the EROS-2000 project. The Rhône river concentration of total selenium averages 2.30 nM with important variations related to river discharge. During estuar-ine mixing, the concentrations of total dissolved selenium, selenite and selenate (calculated as the difference between total dissolved and selenite) decrease linearly with increasing salinity, without significant interconversion between selenium species. In the open Mediterranean waters of the Gulf of Lions the total dissolved selenium increases from 0.5 nM in the surface waters to 0.9 nM in the deep waters. Organic selenium has been observed in Mediterranean deep water, an observation which is different from those from the Atlantic and the Pacific Oceans. The distributions of total inorganic selenium (Σ5e), selenite and selenate are strongly related to phosphate and silicate concentrations as observed previously for the major oceans. 相似文献
4.
The ecological aspect of meiofaunal communities in Can Gio mangrove forest, Ho Chi Minh city, Vietnam has not been investigated
before. The composition, distribution, density and biodiversity of meiofaunal communities were studied along an intertidal
transect at the Khe Nhan mudflat. Each time, three replicate samples were collected in four stations along a transect following
the water line from low tide level up to the mangrove forest edge. In total, 18 meiofaunal taxa were found with the dominant
taxa belonging to Nematoda, Copepoda, Sarcomastigophora and Polychaeta. The densities of meiofauna ranged from 1156 inds/10
cm2 to 2082 inds/10 cm2. The increase in densities from the mangrove forest edge towards the low water line was significant. Along the mudflat transect,
the biodiversity (expressed by different indices) was relatively high at different taxonomic levels but did not vary significantly
along the mudflat except for taxa richness. Eighty nematode genera belonging to 24 families with Comesomatidae having the
highest abundance 33.8 % were found.Theristus andNeochromadora decreased in densities from the lower water line towards the mangrove forest edge, whileParacomesoma andHopperia are typical and more abundant at the middle of the mudflat.Halalaimus increased from high on the mudflat to the low water line. 相似文献
5.
Jesper Raakjær Dao Manh Son Karl-Johan Stæhr Holger Hovgård Nguyen Thi Dieu Thuy Kristine Ellegaard Frank Riget Dang Van Thi Phung Giang Hai 《Marine Policy》2007
Vietnam is in the process of introducing adaptive management based on indicators and time-series to manage its marine fisheries. The development of indicator-based frameworks for fisheries management has accelerated in recent years. This article describes the suite of indicators being suggested or used in Vietnam including the data-collection system. The Vietnamese approach is supported by an institutional structure consisting of a multi-disciplinary advisory system to facilitate the process of using indicators and to introduce knowledge-based management. The article concludes by identifying current problems and weaknesses and by providing suggestions for future improvement of the system. 相似文献
6.
7.
使用氧同位素方法 ,测试了西太平洋马里亚纳岛弧、马里亚纳海槽、冲绳海槽和东太平洋加拉帕戈斯裂谷的海底热液烟囱和硫化物全岩样品。结果表明 :马里亚纳岛弧上的埃斯梅拉尔达破火山口的热液硫化物的形成温度最高 (达 2 75℃ ) ,而成为高温产物的代表 ;冲绳海槽和加拉帕戈斯裂谷烟囱 ,表现为中高温类型 ,其氧同位素温度在 1 5 0℃左右 ;马里亚纳海槽以蛋白石为主要矿物的烟囱物 ,则显示出典型的低温热液类型 ,少量黄铁矿砂试样则表现出中温类型特征。但上述区域大都不同程度地存在有闪锌矿、黄铁矿、黄铜矿等中高温热液矿物 ,说明研究区除马里亚纳海槽明显有中低温热液活动类型外 ,其它区域皆具备中高温热液活动特征 相似文献
8.
J. P. Putaud N. Mihalopoulos B. C. Nguyen J. M. Campin S. Belviso 《Journal of Atmospheric Chemistry》1992,15(2):117-131
Daily measurements of atmospheric sulfur dioxide (SO2) concentrations were performed from March 1989 to January 1991 at Amsterdam Island (37°50 S–77°30 E), a remote site located in the southern Indian Ocean. Long-range transport of continental air masses was studied using Radon (222Rn) as continental tracer. Average monthly SO2 concentrations range from less than 0.2 to 3.9 nmol m-3 (annual average = 0.7 nmol m-3) and present a seasonal cycle with a minimum in winter and a maximum in summer, similar to that described for atmospheric DMS concentrations measured during the same period. Clear diel correlation between atmospheric DMS and SO2 concentrations is also observed during summer. A photochemical box model using measured atmospheric DMS concentrations as input data reproduces the seasonal variations in the measured atmospheric SO2 concentrations within ±30%. Comparing between computed and measured SO2 concentrations allowed us to estimate a yield of SO2 from DMS oxidation of about 70%. 相似文献
9.
Daily measurements of atmospheric concentrations of dimethylsulfide (DMS) were carried out for two years in a marine site at remote area: the Amsterdam Island (37°50S–77°31E) located in the southern Indian Ocean. DMS concentrations were also measured in seawater. A seasonal variation is observed for both DMS in the atmosphere and in the sea-surface. The monthly averages of DMS concentrations in the surface coastal seawater and in the atmosphere ranged, respectively, from 0.3 to 2.0 nmol l-1 and from 1.4 to 11.3 nmol m-3 (34 to 274 pptv), with the highest values in summer. The monthly variation of sea-to-air flux of DMS from the southern Indian Ocean ranges from 0.7 to 4.4 mol m-2 d-1. A factor of 2.3 is observed between summer and winter with mean DMS fluxes of 3.0 and 1.3 mol m-2 d-1, respectively. 相似文献
10.