全文获取类型
收费全文 | 2983篇 |
免费 | 315篇 |
国内免费 | 416篇 |
专业分类
测绘学 | 107篇 |
大气科学 | 94篇 |
地球物理 | 636篇 |
地质学 | 639篇 |
海洋学 | 1415篇 |
天文学 | 12篇 |
综合类 | 150篇 |
自然地理 | 661篇 |
出版年
2024年 | 24篇 |
2023年 | 58篇 |
2022年 | 104篇 |
2021年 | 117篇 |
2020年 | 132篇 |
2019年 | 130篇 |
2018年 | 120篇 |
2017年 | 127篇 |
2016年 | 143篇 |
2015年 | 117篇 |
2014年 | 165篇 |
2013年 | 224篇 |
2012年 | 114篇 |
2011年 | 192篇 |
2010年 | 150篇 |
2009年 | 165篇 |
2008年 | 167篇 |
2007年 | 145篇 |
2006年 | 161篇 |
2005年 | 135篇 |
2004年 | 115篇 |
2003年 | 115篇 |
2002年 | 97篇 |
2001年 | 77篇 |
2000年 | 90篇 |
1999年 | 91篇 |
1998年 | 70篇 |
1997年 | 69篇 |
1996年 | 45篇 |
1995年 | 52篇 |
1994年 | 52篇 |
1993年 | 34篇 |
1992年 | 34篇 |
1991年 | 16篇 |
1990年 | 14篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1979年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有3714条查询结果,搜索用时 15 毫秒
131.
Damir Vilicic Milivoj Kuzmic Igor Tomažić Zrinka Ljubešić Sunčica Bosak Robert Precali Tamara Djakovac Danijela Marić Jelena Godrijan 《Marine Ecology》2013,34(4):451-466
A 275‐km‐long transversel Northern Adriatic profile from the mouth of the Po River (Italian Adriatic coast) to the Kvarner region (Croatian coastal island area) was investigated in three successive case studies in August 2008, 2009 and 2010. The short Po River pulses in August result in the surface advection of riverine water, nutrients and phytoplankton from the western to the eastern side of the Adriatic. This surface spreading exhibits inter‐annual variability depending on the riverine discharge in the preceding period. The Po River discharge pulse in August 2010 in particular resulted in an extraordinary tongue‐like advection of riverine water, nutrients, and phytoplankton towards the Eastern Adriatic coast. The phenomenon was detected using both satellite imagery and classical oceanographic measurements. In the advective water, toxic dinoflagellates were most abundant in August 2010, when the influence of the Po was greatest. 相似文献
132.
N. H. McCarter 《新西兰海洋与淡水研究杂志》2013,47(4):551-559
The diet of brown trout (Salmo trutta) and rainbow trout (S. gairdnerii) was studied in specimens from Lake Benmore, a deep, oligo‐trophic lake in South Island, New Zealand. Between November and July, both species fed mainly on small molluscs (Potamopyrgus antipodarum, Physa sp., and Gyraulus corinna) gleaned from the littoral weed beds. Energy values for the three species of mollusc were determined: P. antipodarum, 6000 J g‐1; G. corinna, 5500 J g‐1; Physa sp., 9800 J g‐1. Potamopyrgus antipodarum yielded little energy to the fish, unless its shell broke during passage through the gut. Physa sp. was the most profitable mollusc, irrespective of shell breakage and Potamopyrgus antipodanim the least profitable. The mean energy value per snail for G. corinna and Physa sp. eaten by rainbow trout was 25–30% less than for snails eaten by brown trout, possibly because rainbow trout ingested empty shells from the sediment surface. Rainbow trout extracted about 20% more energy than brown trout from unbroken shells. In July, 84% of the brown trout switched to predation of common bullies, Gobio‐morphus cotidianus, probably as a result of bully reproductive behaviour. Rainbow trout did not show the same change, apparently because they were feeding in deeper water where few bullies were available. The low‐energy diet and its possible connection with growth rate are discussed. 相似文献
133.
134.
The zooplankton of oligotrophic lakes in North Patagonia is often dominated by mixotrophic ciliates, particularly Stentor amethystinus and Stentor araucanus. Therefore, we tested whether Stentor spp. (i) is an important food for juvenile endemic (Cheirodon australe, Galaxias maculatus, Odontesthes mauleanum, Percichthys trucha) and introduced (Oncorhynchus mykiss) fish species, and (ii) represents a remarkable grazer of bacteria. Ingestion rates of fish estimated by disappearance of Stentor in feeding experiments ranged between 8 (G. maculatus) and 53 (C. australe) ciliates per fish and day, and assimilation rates measured by using radioactively labelled Stentor ranged between 3 (P. trucha) and 52 (C. australe) ciliates per fish and day. However, although we detected the consumption of Stentor by fish, the daily consumption amounted to at most 0.2% of the fish biomass which can not cover the energy requirement of the fish. Furthermore, the daily consumption was equivalent to a maximum of 1.6% of the Stentor standing stock so that fish predation does not seem to be an important mortality factor for the ciliates. The clearance rate of Stentor sp. on natural bacteria was on average 3.8 μl cil−1 h−1. The daily ingestion (mean 3.9 ng C cil−1 d−1) was about 3.5% of the individual biomass of Stentor sp. Therefore, bacteria ingestion might explain a ciliate growth rate of appr. 1% d−1, which was about 17% of the photosynthesis of endosymbiotic algae. The maximum density of Stentor sp. in the lake could ingest about 1 μg C L−1 d−1 bacteria which is only 3% of average bacterial production. Thus, grazing by Stentor sp. does not seem to be a main loss factor for the bacteria. 相似文献
135.
136.
The earthquake and tsunami that devastated coastal area in Nanggroe Aceh Darussalam Province and North Sumatra Province,especially Nias Island on December 26,2004,caused damage to most mangrove and coastal forests in the areas.Before the 2004 tsunami,there is no report or publication about mangrove and coastal vegetation in Nias Island.The aims of this research were to describe the mangrove forests and coastal vegetation after tsunami disaster and to learn the ecological functions of mangrove forests and co... 相似文献
137.
David Gregory 《New Zealand geographer》2008,64(2):144-153
Abstract: In this paper the proposed New Zealand Coastal Policy Statement is set within the context of its Resource Management Act legislative framework and in terms of the evolution of the fundamental influence of policy statements on coastal management in New Zealand. This discussion is coupled with an examination of the development of strong policy directions in the proposed statement and the potential impact of giving effect to these policies on the regional and unitary authorities tasked with this responsibility. 相似文献
138.
139.
140.