全文获取类型
收费全文 | 11259篇 |
免费 | 2112篇 |
国内免费 | 3256篇 |
专业分类
测绘学 | 1064篇 |
大气科学 | 2550篇 |
地球物理 | 2117篇 |
地质学 | 3715篇 |
海洋学 | 4375篇 |
天文学 | 378篇 |
综合类 | 865篇 |
自然地理 | 1563篇 |
出版年
2024年 | 62篇 |
2023年 | 152篇 |
2022年 | 386篇 |
2021年 | 481篇 |
2020年 | 496篇 |
2019年 | 660篇 |
2018年 | 526篇 |
2017年 | 552篇 |
2016年 | 527篇 |
2015年 | 623篇 |
2014年 | 723篇 |
2013年 | 892篇 |
2012年 | 682篇 |
2011年 | 710篇 |
2010年 | 612篇 |
2009年 | 823篇 |
2008年 | 770篇 |
2007年 | 832篇 |
2006年 | 747篇 |
2005年 | 660篇 |
2004年 | 616篇 |
2003年 | 511篇 |
2002年 | 495篇 |
2001年 | 423篇 |
2000年 | 370篇 |
1999年 | 359篇 |
1998年 | 312篇 |
1997年 | 275篇 |
1996年 | 255篇 |
1995年 | 191篇 |
1994年 | 181篇 |
1993年 | 172篇 |
1992年 | 128篇 |
1991年 | 86篇 |
1990年 | 82篇 |
1989年 | 49篇 |
1988年 | 43篇 |
1987年 | 32篇 |
1986年 | 14篇 |
1985年 | 29篇 |
1984年 | 12篇 |
1983年 | 18篇 |
1982年 | 20篇 |
1981年 | 15篇 |
1980年 | 2篇 |
1979年 | 9篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1954年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 851 毫秒
51.
Application of LICOM to the numerical study of the water exchangebetween the South China Sea and its adjacent oceans 总被引:8,自引:1,他引:8
1 IntroductionThe South China Sea (SCS) is the largestmarginal sea in the western Pacific (see Fig. 1). It con-nects with the SCS through the Taiwan Strait, with thePacific through the Luzon Strait, with the Sulu Seathrough the Mindoro and Balabac Straits and with theJava Sea and Andaman Sea through the Sunda Shelf(For convenience, here we refer to the section at 1.5°N,Fig. 2). It is shown that the seasonal SCS circulation ismostly affected by the summer/winter monsoon, andthe no… 相似文献
52.
Tatsuya?IwataEmail author Yoshiko?Shinomura Yuta?Natori Yasumasa?Igarashi Rumi?Sohrin Yoshimi?Suzuki 《Journal of Oceanography》2005,61(4):721-732
We investigated the water structure and nutrient distribution in the Suruga Bay from April 2000 to July 2002, especially the Offshore Water, which occupies a large part of the bay. The maximum salinity in the upper 200 m varied between 34.49 and 34.71, indicating a temporal change in the influence of Kuroshio Water on the Offshore Water. Seasonal variation in nutrient concentrations was largest from surface to 50 m. On the other hand, the variance in nutrient concentrations within each season was largest in the subsurface layer of 100–300 m in spring, summer and fall. In the Offshore Water, the change of nutrients was negatively correlated with that of salinity in each season. This suggests that an increasing intrusion of saline water brings about a lower nutrient concentration in the Offshore Water. Likewise, negative correlations were observed between the change of the maximum salinity and chlorophyll a (Δ [chl.a-int])/nutrients integrated in the upper 200 m. Δ[chl.a-int] was significantly correlated with the changes of nitrate and phosphorus, but there were no significant correlations between Δ[chl.a-int] and the change of silicate. These results suggest that the concentrations of chlorophyll a and nutrients in the Offshore Water were decreased due to the increasing intrusion of Kuroshio Water. The Offshore Water is likely to be related to the regulation of primary production by nitrate. 相似文献
53.
54.
55.
56.
太平洋海域海平面变化的灰色系统分析 总被引:3,自引:1,他引:3
应用灰色系统理论,对太平洋海域48个长期验潮站的月均海平面分别建立了GM(1,1)模型。GM(1,1)模型能较好地反映太平洋海域的海平面变化的趋势,它除了能给出连续的海平面变化速率外,同时能方便地给出海平面变化的加速率。模拟结果表明,在太平洋地壳均衡假设下,太平洋海域的月均海平面以平均速率0.17cm/a上升。在太平洋海域所取的48个长期验潮站中,有40个站在加速上升,全部站的平均加速度为0.00029cm/a2。且加速率逐渐增大。当然这些加速率都很小,但作为一种普遍性的趋势,这已足以说明:太平洋海域的海平面在加速上升 相似文献
57.
W.R. Geyer 《Estuarine, Coastal and Shelf Science》1997,44(6):713-722
Observations of two small estuaries in Cape Cod, U.S.A. indicate large variations in salinity structure that are forced by variations in along-estuary wind stress. During onshore winds, the estuarine circulation is reduced, and the along-estuary salinity gradient increases as freshwater accumulates. During offshore winds, the surface outflow is enhanced, freshwater is flushed out of the estuary, and the along-estuary salinity gradient becomes weak. Constrictions block the wind-induced flushing, resulting in strong salinity fronts across the constrictions. The residence time of one of the estuaries varies by more than a factor of three in response to variations in wind-induced flushing. The other estuary has little variation of flushing associated with winds, due to a constriction at the mouth that inhibits the wind-induced exchange. The strong influence of winds on the flushing of these estuaries is due in part to their shallow depths, which accentuates the influence of wind stress relative to the effects of the horizontal density gradient. In addition, the residence times of the estuaries are comparable to the time scale of wind forcing, allowing large changes in water properties during wind events. 相似文献
58.
Farn Parungo Clarence Nagamoto Cecilia M. I. R. Girz Jeff Torgerson Zhou Mingyu 《海洋学报(英文版)》1995,14(2):201-207
ObservationofcloudsandsolarradiationoverthePacificOceanasrelationtoglobalclimate¥FarnParungo;ClarenceNagamoto;CeciliaM.I.R.Gi... 相似文献
59.
用自装的BET容量法装置测定了几种粒状钛型吸附剂的比表面及其孔径分布。测定是在常温减压下进行的。结果表明:钛型吸附剂在加铀海水中的吸铀量与样品的比表面及孔径分布有一定的内在联系。这种表面性质的研究对吸附剂的筛选有重要的指导意义。 相似文献
60.
K. G. Robertson 《Marine Geophysical Researches》1990,12(1-2):3-8
Accurate navigation forms an essential part of all research at sea and the deep ocean imposes it's own unique problems. This chapter discusses several of the techniques in current use on the research vessels of the Natural Environment Research Council (NERC), concentrating on those systems which provide global navigation facilities, as opposed to the more localised, coastal aids. Whilst most of the systems rely on surface propagation of radio waves, the use of acoustics and sea-bed mapping instruments constitute accurate alternatives for some sub-sea applications. 相似文献