全文获取类型
收费全文 | 537篇 |
免费 | 61篇 |
国内免费 | 201篇 |
专业分类
测绘学 | 6篇 |
大气科学 | 38篇 |
地球物理 | 75篇 |
地质学 | 63篇 |
海洋学 | 551篇 |
综合类 | 28篇 |
自然地理 | 38篇 |
出版年
2024年 | 2篇 |
2023年 | 8篇 |
2022年 | 11篇 |
2021年 | 18篇 |
2020年 | 26篇 |
2019年 | 28篇 |
2018年 | 19篇 |
2017年 | 25篇 |
2016年 | 26篇 |
2015年 | 32篇 |
2014年 | 24篇 |
2013年 | 44篇 |
2012年 | 31篇 |
2011年 | 42篇 |
2010年 | 27篇 |
2009年 | 33篇 |
2008年 | 46篇 |
2007年 | 24篇 |
2006年 | 24篇 |
2005年 | 36篇 |
2004年 | 22篇 |
2003年 | 20篇 |
2002年 | 28篇 |
2001年 | 20篇 |
2000年 | 26篇 |
1999年 | 20篇 |
1998年 | 23篇 |
1997年 | 19篇 |
1996年 | 13篇 |
1995年 | 15篇 |
1994年 | 14篇 |
1993年 | 10篇 |
1992年 | 20篇 |
1991年 | 11篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1984年 | 1篇 |
排序方式: 共有799条查询结果,搜索用时 10 毫秒
191.
本文系根据1980~1989年福建省在台湾海峡生产的48组具有代表性的标本船之技术经济资料,以柯布·道格拉斯生产函数和经济指标评析其生产状况及技术经济效果。结果表明,近年来,福建省灯光围网渔船的宏观技术水平已明显提高;然而因其捕捞努力量大幅度增加,单位捕捞努力量渔获量曲线呈抛物线状,其长期趋势为CPUE=-0.311+0.9032f-0.06397f~2;预测投资在功率范围为147~294kW的灯光圈网渔船在台湾海峡生产可望受益。 相似文献
192.
Keisuke?Yamaguchi Ju?Lin Arata?KanekoEmail author Tokuo?Yayamoto Noriaki?Gohda Hong-Quang?Nguyen Hong?Zheng 《Journal of Oceanography》2005,61(2):283-294
Tidal current structures at the Hayatomono-Seto of the Kanmon Strait are mapped continuously during March 17 to 20, 2003, including a spring tide, by the eight coastal acoustic tomography (CAT) systems distributed on both the sides of the strait. Detailed structures of strong tidal currents and their associated vortices are well reconstructed by the inverse analysis of travel-time difference data obtained from the reciprocal sound transmission between the paired CAT systems located at both sides of the strait mainly. The results are well compared to the shipboard acoustic Doppler current profiler (ADCP) data at the correlation rate of 0.84/0.82 and the RMS difference of 0.47/0.48 ms−1 for the east-west/north-south current after the selection of good data. During the observation period, the maximum hourly mean volume transport for the upper 7 m layer across the strait reached 13,314 m3 s−1 for the eastward and 5,547 m3 s−1 for the westward. The daily mean transport is directed to the eastward and estimated 1,470 m3 s−1 and 2,140 m3 s−1 for March 18 and 19, respectively, when a spring tide occurs. 相似文献
193.
根据2001年3月份南海东北部航次调查温、盐资料,分析了2001年冬末春初南海东北部温、盐结构和环流的特征.分析结果表明:观测期间南海东北部环流主要受一次海盆尺度气旋型冷环流支配,冷环流呈现双核结构,垂向尺度接近1000 m.吕宋海峡内侧断面的水交换在600 m以浅海水流入南海,在断面南部(20°N以南)中层和深层有流出,断面法向地转流向西净输运量为6.9×106m3/s;直接的黑潮入侵不超过120.5°E,但有部分的黑潮水沿陆坡达到台湾岛西南部海域,并更有一部分逸入东沙岛以西海域,与南海水混合变性. 相似文献
194.
台湾海峡沉积盆地的演化与油气远景 总被引:2,自引:0,他引:2
台湾海峡沉积盆地新生代以来构造演化经历了早第三纪陆缘裂谷、晚第三纪挤压收缩和第四纪隆起封闭等发育阶段,属残留陆缘裂谷,具有良好的油气远景,其中,海峡中部油气远景最佳。 相似文献
195.
lvaro Peliz Ana Teles-Machado Patrick Marchesiello Jesus Dubert Jesus Garcia Lafuente 《Dynamics of Atmospheres and Oceans》2009,46(1-4):36-45
We present a case study of the generation of a cold filament rooted off the southwestern edge of the Strait of Gibraltar (Atlantic side) during the summer of 2000. The event is successfully simulated using high-resolution atmospheric and oceanic numerical models. It is shown that a sharp filament may develop oceanwards with little modification of the Atlantic inflow into the Mediterranean, contrary to usual expectations. The filament is essentially driven by the surface layer response to Gap winds occurring during Levanter conditions. The easterly wind funnelling in the Strait generates a strong wind jet and intense wind curl which impacts the oceanic surface layer through Ekman pumping and mixing processes. The generation and fate of the filament is very similar to the Gulf of Tehuantepec case, where strong Gap wind events produce asymmetric deformation and erosion of the thermocline that tends to favour anticyclonic mesoscale circulations. Our observations and model results from both realistic and idealized experiments suggest that similar phenomena are present in the Gulf of Cadiz, but they are altered by the persisting Atlantic inflow, so that the response to Gap winds is not as dramatic. 相似文献
196.
Spatial variability in community structure of dictyoceratid sponges (class Demospongiae; order Dictyoceratida) was examined on coral reefs in Torres Strait, an archipelago of islands and reefs between northern Queensland, Australia, and Papua New Guinea. Dictyoceratid sponge abundances and environmental factors were recorded at four locations, separated by 50–220 km. Each location was subdivided into 5–7 sites, each ?2 km apart. At each site, four 50×2 m belt transects were quantitatively surveyed, recording the dictyoceratid numbers, substrate type (rock, rubble and sand), water clarity, degree of reef slope and depth. Dictyoceratid abundance was similar among locations over large spatial scales, averaging 15.5 individuals per 100 m2, but varied significantly among sites within particular locations (i.e. small scale heterogeneity). Twenty-three dictyoceratid species were recorded in Torres Strait, with approximately half (12/23) found in only one location. The canonical correspondence analysis determined that the measured environmental factors explained only 26% of the spatial variation. Cluster analysis revealed a complex dictyoceratid community structure with similarities among neighbouring sites and among sites separated by hundreds of kilometres. Conversely the abundance and composition of dictyoceratids could vary greatly between neighbouring sites 2 km apart and on the same reef complex. The results of this study suggest that spatial variability of dictyoceratid sponges in Torres Strait is influenced by a combination of environmental, biological and stochastic processes. 相似文献
197.
Spatial and temporal variability of the absorption properties of colored dissolved organic matter (CDOM) in the Taiwan Strait was investigated in summer (July to August of 2006) and winter (from December 2006 to January of 2007) seasons. The CDOM absorption coefficient at 280 nm (a 280 ) showed a decreasing trend from nearshore to offshore areas while the spectral slope coefficient parameter calculated between wavelengths 275-295 nm (S 275 295 ) showed an increase, indicative of decreasing aromaticity and molecular weight of the CDOM. The average a 280 in winter (1.47 ± 0.50 m 1 ) was significantly higher than in summer (1.10 ± 0.41 m 1 ), while the average S 275 295 in winter (26.7 ± 5.2 μm 1 ) was significantly lower than in summer (30.6 ± 5.5 μm 1 ), demonstrating clear seasonal variation in CDOM abundance and properties in the Taiwan Strait. A three-end- member conservative mixing model showed that local terrestrial CDOM inputs from several rivers along the western coast were small (<5%). However, the distribution of CDOM in the Taiwan Strait is mainly controlled by water mass movement [i.e., the Zhe-min Coastal Current (ZCC) and the Kuroshio Branch Current (KBC) in winter and the South China Sea Water (SCSW) in summer]. Biological activity was also an important factor affecting the distribution of CDOM in the offshore region in summer months. 相似文献
198.
Xiaoxia Tu Chonghui Wang Qunhui Yang Benduo Zhu 《Marine Georesources & Geotechnology》2020,38(7):876-886
AbstractThe geochemical characteristics and Pb isotope variations in Fe-Mn deposits collected from the South China Sea (SCS) were studied in this paper. The mineralogical and chemical composition data indicate that the deposits are almost all hydrogenetic in origin. Compared with the Fe-Mn deposits in other oceans, the SCS Fe-Mn deposits have a significantly higher Pb content because of higher material supply in addition to a lower growth rate of the deposits. Pb isotope ratios in the surface of the SCS Fe-Mn deposits are relatively uniform, with a characteristic of relatively lower 206Pb/204Pb ratio. The Pb isotopic compositions of the SCS Fe-Mn deposits are controlled by the Pacific Deep Water and local inputs, which include eolian dust from the Asian continent and weathering products from Taiwan, Luzon and SCS submarine volcanic rocks. The continuously increasing 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios along the transect of nodule D581 over the past 3.5?Ma are affected by the stepwise closure of the Luzon Strait that reduced volcanic material supply and the deep current strengthen at the same time. 相似文献
199.
黑潮入侵南海对南海的温盐平衡、环流、涡旋和局地气候等具有重要作用。基于吕宋海峡处黑潮不同流径的识别方法,对1993~2021年的卫星高度计资料进行识别,获取黑潮不同流径的发生时间,探究黑潮入侵南海流径的时间变化规律。结果表明:(1)黑潮主要以流套(Looping)和分支(Leaking)两种流径入侵南海,Leaking流径发生的时长(710周)和概率(46.9%)要远高于Looping流径(时长218周,概率14.4%)。(2) Looping流径和Leaking流径均可将高温高盐的西北太平洋水带入南海,Looping流径下的平均吕宋海峡上层通量(6.3×106 m3/s)略大于Leaking流径(5.6×106 m3/s)Looping和Leaking流径在4×106 m3/s~6×106 m3/s区间发生时间最长。(3)季节变化上,Looping流径主要发生在冬季,Leaking流径在冬半年均较强,夏季二者发... 相似文献
200.
Several characteristics of water exchange in the Luzon Strait 总被引:1,自引:0,他引:1
1IntroductionTheLuzonChannelissituatedonthewest-ernsideofthenorthernPacificandbetweenTaiwanandLuzonIslands.ItisthemainpassageofthePacificwaterenteringtheSCS.Therearenumerousdifferent-sizedislandsformingmanynarrowwaterpassagesinthischannel,sotheLuzonChannelisthegeneralnameofthesepas-sages(includingBabuyan,BalintangandBashiChannels,etc.).Customarily,theLuzonStraitiscalledtheBashiChannel.Itswidthis386kmandhasameandepthof1400m. Toagreatextent,thehydro-meteorologi-calconditionso… 相似文献