全文获取类型
| 收费全文 | 311篇 |
| 免费 | 273篇 |
| 国内免费 | 70篇 |
专业分类
| 测绘学 | 2篇 |
| 大气科学 | 8篇 |
| 地球物理 | 23篇 |
| 地质学 | 75篇 |
| 海洋学 | 484篇 |
| 综合类 | 56篇 |
| 自然地理 | 6篇 |
出版年
| 2024年 | 13篇 |
| 2023年 | 39篇 |
| 2022年 | 26篇 |
| 2021年 | 40篇 |
| 2020年 | 53篇 |
| 2019年 | 58篇 |
| 2018年 | 53篇 |
| 2017年 | 13篇 |
| 2016年 | 4篇 |
| 2015年 | 14篇 |
| 2014年 | 16篇 |
| 2013年 | 8篇 |
| 2012年 | 9篇 |
| 2011年 | 11篇 |
| 2010年 | 15篇 |
| 2009年 | 20篇 |
| 2008年 | 17篇 |
| 2007年 | 29篇 |
| 2006年 | 26篇 |
| 2005年 | 16篇 |
| 2004年 | 9篇 |
| 2003年 | 13篇 |
| 2002年 | 16篇 |
| 2001年 | 15篇 |
| 2000年 | 16篇 |
| 1999年 | 18篇 |
| 1998年 | 14篇 |
| 1997年 | 10篇 |
| 1996年 | 9篇 |
| 1995年 | 5篇 |
| 1994年 | 7篇 |
| 1993年 | 10篇 |
| 1992年 | 9篇 |
| 1991年 | 5篇 |
| 1990年 | 9篇 |
| 1989年 | 6篇 |
| 1988年 | 1篇 |
| 1981年 | 1篇 |
| 1964年 | 1篇 |
排序方式： 共有654条查询结果，搜索用时 31 毫秒
31.
32.
33.
Supriyo Das 《中国地球化学学报》2006,25(B08):24-25
The Raniganj Coalfield is the oldest coalfield in India that has been continuously and extensively mined since the late eighteenth century. The present study reports a geochemical investigation and environmental quality assessment using soil and water in the area surrounding a stream, locally known as Singaran Nala （Nala means storm water drains in Bengali）, in the Raniganj Coalfield. Soil （top soil, mud, silty clay and laterite） and rock samples （sandstone and shale） were collected from the study area and were analyzed for trace metals （Cr, Cu, Fe, Mn, Ni and Zn）. Surface waters from the stream and the Damodar River as well as ground waters from hand pumps and underground mine pits were collected. Water samples were analyzed for major ions （Na^＋, Ca^2＋, Mg^2＋, Cl^-, HNO3^- and SO4^2-） and trace metals （Cu, Fe, Mn, Ni, and Zn）. Trace metal concentrations in soil samples are found higher than the average world soil composition. Nevertheless, trace metal （Cr, Cu, Ni and Zn） concentrations in soils exceed or reach the maximum allowable concentrations （MAC） proposed by the European Commission for agricultural soils. In particular, Ni concentrations exceed the typical value for cultivated soils. Chromium, Cu and Ni concentrations in laterite and Cr concentration in topsoil exceed the ecotoxicological limit. 相似文献
34.
35.
Edward Derbyshire 《中国地球化学学报》2006,25(B08):219-219
Fine atmospheric dust includes mineral particles and aggregates, fibrous minerals and fibrous organic material. Generation, dislodgement and transport （deflation） of natural dust with the finer （〈4 microns） components suspended as silt-size aggregates, is widespread in and adjacent to the world＇s drylands, as well as deriving from volcanic vents. Silica is a highly fibrogenic agent in lung tissue. Long-term inhaling of siliceous dusts can lead to a number of fibrotic lung diseases, including natural （non-occupational） pneumoconioses （notably silicosis, but including asbestosis and others）. Different polymorphs of silica show different levels of toxicity in interaction with lung tissue. Particles with highly active surfaces may release radicals, causing cell damage. Some types of inhaled particulates are degraded by macrophages, but many are highly resistant and persist in the lungs, some stimulating fibroblastic cells to deposit collagen. Silicosis is an inflammation of the lung commonly caused by silicate mineral particles, leading to fibrosis. Three types are recognized： nodular pulmonary fibrosis （simple or chronic silicosis）, acute silicosis, and accelerated silicosis. Generally, finer particulates have greater oxidative capacity than the coarser fractions. They contain more reactive oxygen species, their greater bioreactivity making them more toxic to pulmonary tissue. Nevertheless, inhalation of large dust particles （〉 10μm） may constitute a health risk if the mineralogy is toxic, regardless of where the grains lodge in the respiratory system. Dust may absorb harmful gases, disease-generating bacteria and carcinogenic hydrocarbon compounds. Silica-related respiratory disease may also an exacerbate cardiac problem, and epidemiology suggests a link with tuberculosis. Quantification of dust loading and exposure requires study of spatial and temporal patterns, supported by meteorological analysis, airflow modeling and satellite-borne imagery. Some acute, short-term health impacts have been assessed using atmospheric and health records both before and after a dust storm or by comparison of populations within and outside such events. Analysis of the size, shape, mineralogy and geochemistry of ambient dust particulates provides information on natural dust sources, dust concentrations, and potential particulate toxicity, as well as providing a datum for assessment of human exposure levels. 相似文献
36.
Toxic and radioactive elements in soils and vegetation of natural and technogenic geosystems of Pribaikalye （Lake Baikal region） 总被引：1，自引：0，他引：1
《中国地球化学学报》2006,25(B08):245-245
37.
《中国地球化学学报》2006,25(B08):127-128
38.
环境水样中砷的化学形态分析 总被引：1，自引：0，他引：1
由于砷的化学形态不同,在环境中的毒性、分布、生物效应亦不相同,因而砷的形态分析在环境监测治理中有着不可忽视的重要作用.砷的形态分析 相似文献
39.
有毒铜绿微囊藻对鱼和溞的毒性 总被引：12，自引：2，他引：12
用有毒铜绿微囊藻细胞及其从毒细胞中提取的毒素喂养和腹腔注射鱼类，结果表明：（1）微囊藻毒素MCYST－LR对所有实验过的鱼有毒害作用（LD_(50)为110－500μg／kg）．注射毒素24h后，鱼肝电镜超微结构观察均表现出肝损伤．（2）在受控条件下，当用有毒铜绿微囊藻作为食物喂养日鲢和罗非鱼时，鱼类能在以毒藻为唯一食物的环境中生活20d以上．白鲢和罗非鱼粪便的毒性比喂食藻类的毒性分别降低约2—4．5倍，其肝的超微结构现察仍有轻度损伤．（3）在培养液中加入15μg／mLMCYST－LR和用实验室纯培养的铜绿微囊藻作为食物培养枝角类时，均可使它们在48h死亡．以无毒微囊藻培养时则生长不良亦不怀卵，表明它不是枝角类合适的食物． 相似文献
40.
