全文获取类型
| 收费全文 | 484篇 |
| 免费 | 33篇 |
| 国内免费 | 118篇 |
专业分类
| 测绘学 | 6篇 |
| 大气科学 | 11篇 |
| 地球物理 | 220篇 |
| 地质学 | 79篇 |
| 海洋学 | 264篇 |
| 综合类 | 39篇 |
| 自然地理 | 16篇 |
出版年
| 2024年 | 9篇 |
| 2023年 | 23篇 |
| 2022年 | 24篇 |
| 2021年 | 19篇 |
| 2020年 | 22篇 |
| 2019年 | 23篇 |
| 2018年 | 28篇 |
| 2017年 | 16篇 |
| 2016年 | 21篇 |
| 2015年 | 24篇 |
| 2014年 | 28篇 |
| 2013年 | 23篇 |
| 2012年 | 32篇 |
| 2011年 | 48篇 |
| 2010年 | 23篇 |
| 2009年 | 31篇 |
| 2008年 | 37篇 |
| 2007年 | 24篇 |
| 2006年 | 28篇 |
| 2005年 | 20篇 |
| 2004年 | 17篇 |
| 2003年 | 8篇 |
| 2002年 | 14篇 |
| 2001年 | 10篇 |
| 2000年 | 7篇 |
| 1999年 | 13篇 |
| 1998年 | 13篇 |
| 1997年 | 9篇 |
| 1996年 | 10篇 |
| 1995年 | 5篇 |
| 1994年 | 4篇 |
| 1993年 | 4篇 |
| 1992年 | 7篇 |
| 1991年 | 2篇 |
| 1990年 | 1篇 |
| 1989年 | 1篇 |
| 1988年 | 1篇 |
| 1986年 | 1篇 |
| 1985年 | 2篇 |
| 1984年 | 1篇 |
| 1982年 | 2篇 |
排序方式： 共有635条查询结果，搜索用时 46 毫秒
41.
The distribution of chlorophyll a and its influencing factors in different regions of the Bering Sea
The distribution of chlorophyll a(Chl a) and its relationships with physical and chemical parameters in different regions of the Bering Sea were discussed in July 2010. The results showed the seawater column Chl a concentrations were 13.41–553.89 mg/m2 and the average value was 118.15 mg/m2 in the study areas. The horizontal distribution of Chl a varied remarkably from basin to shelf in the Bering Sea. The regional order of Chl a concentrations from low to high was basin, slope, outer shelf, inner shelf, and middle shelf. The vertical distribution of Chl a was grouped mainly from single-peak type in basin, slope, outer shelf, and middle shelf, where the deep Chl a maxima(DCM) layer was observed at 25–50 m, 30–35 m, 36–44 m, and 37–47 m, respectively. The vertical distribution of Chl a mainly had three basic patterns: standard single-peak type, surface maximum type, and bottom maximum type in the inner shelf. The analysis also showed that the transportation of ocean currents may control the distribution of Chl a, and the effects were not simple in the basin of the Bering Sea. There was a positive correlation between Chl a and temperature, but no significant correlation between Chl a and nutrients. The Bering Sea slope was an area deeply influenced by slope current. Silicate was the factor that controlled the distribution of Chl a within parts of the water in the slope. Light intensity was an important environmental factor in controlling seawater column Chl a in the shelf, where Chl a was limited by nitrate rather than phosphate within the upper water. Meanwhile, there was a positive relationship between Chl a and salinity. Algal blooms broke out at Sta. B6 of the southwestern St. Lawrence Island and Stas F6 and F11 in the middle of the Bering Strait. 相似文献
42.
43.
Kathleen NICOLL 《《地质学报》英文版》2014,88(Z1):94-95
正1 Introduction The Great Salt Lake(GSL)is the defining hydrological feature of the Great Basin,North America’s largest desert--and it is the largest waterbody in the western USA.Despite the early(Eardley,1938)recognition of"bioherms,"algal layers,and mats covering hundreds of square km of lake area,these features have not been the 相似文献
44.
Microcystis bloom, one of the most objectionable characteristics of eutrophication in tropical and subtropical waters, occurred in Donghu Lake (East lake) of Wuhan every summer from the 1970s up to 1984, but from 1985 up to now failed to occur there. The cause of its disappearance rema-ined in obscurity until recently. In situ enclosure experiments in the lake for three years showed that the stocking of the filter-feeding silver carp ( Hypophthalmichthys molitrix ) and big-head carp (Aristichthys nobilis ) played a decisive role in eliminating Microcystis bloom from the lake; but that recurrence of the bloom is possible under certain conditions. This paper presents the details and the results of enclosure ex-periments. The authors‘ analysis of fish biomass data obtained by echo-sounding and the fishery produc-tion of the lake over the years, revealed that the recurrence of Microcystis bloom can be prevented so long as the combined biomnss of silver carp and big-head carp remains at or exceeds 50 g per cubic meter of lakewater, as was the case in the lake‘s 1985 fish yield of 1015 t. 相似文献
45.
鄂尔多斯盆地上三叠统延长组长7段富有机质页岩是该盆地中生界含油系统的主力烃源岩,其有机质丰度高,类型好,具有巨大的生烃潜力。该套烃源岩中有机质的富集很大程度上取决于长7期的高古生产力及其提供的充足的有机质。长7期藻类勃发的存在已被多数学者所接受,但是目前还缺乏直观、有力的证据。笔者等通过薄片和扫描电镜观察、能谱分析,在长7段的脉状黄铁矿附近和碳酸盐结核中发现了属种单一、分布丰度高的藻类化石,它们呈现出近似球状的轮廓,在中部分布着一条裂缝。这些藻类化石的发现具有重要的地质意义,它为长7期的藻类勃发提供了很好的证据,也为该时期热液活动的重要作用提供了有力的支撑。 相似文献
46.
47.
基于太湖31个站点的逐月监测数据,分析了2007-2019年太湖藻型湖区和草型湖区的叶绿素a变化特征,并分析研究不同环境因子对不同类型湖区叶绿素a的影响.结果表明,近年来太湖不同类型湖区的总磷浓度和叶绿素a浓度变化基本一致,均呈波动上升趋势.不同类型湖区的总磷浓度拐点均为2015年,叶绿素a浓度拐点均为2016年.最低月平均水温、前冬积温、年平均水温、年均风速与藻型湖区和草型湖区叶绿素a浓度均呈显著相关.沉水植物分布面积与草型湖区叶绿素a浓度之间呈显著相关.湖西区年内和年度降雨剧烈变化,湖西区年降雨量与不同类型湖区当年叶绿素a浓度的关系不明显,5日极端降雨量与不同类型湖区下年度叶绿素a浓度均呈显著正相关.太湖蓝藻水华强度在短期内可能仍会处于较高水平,迫切需要高度重视高温时段太湖蓝藻打捞处置工作,保障饮用水安全;同时,要进一步加强湖西区强降雨期间的非点源污染防控措施研究,推动入湖污染通量稳步降低,并探索东西山之间及东茭咀附近水域沉水植物生态修复技术,降低风浪扰动作用,尽快恢复相关重要水域的沉水植物. 相似文献
48.
49.
50.