全文获取类型
收费全文 | 210篇 |
免费 | 38篇 |
国内免费 | 66篇 |
专业分类
测绘学 | 30篇 |
大气科学 | 52篇 |
地球物理 | 23篇 |
地质学 | 64篇 |
海洋学 | 103篇 |
天文学 | 3篇 |
综合类 | 23篇 |
自然地理 | 16篇 |
出版年
2024年 | 3篇 |
2023年 | 7篇 |
2022年 | 6篇 |
2021年 | 10篇 |
2020年 | 6篇 |
2019年 | 15篇 |
2018年 | 17篇 |
2017年 | 11篇 |
2016年 | 15篇 |
2015年 | 7篇 |
2014年 | 31篇 |
2013年 | 10篇 |
2012年 | 11篇 |
2011年 | 18篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 10篇 |
2007年 | 12篇 |
2006年 | 17篇 |
2005年 | 8篇 |
2004年 | 8篇 |
2003年 | 3篇 |
2002年 | 10篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
排序方式: 共有314条查询结果,搜索用时 15 毫秒
71.
On the basis of the simple dynamic model of circulation developed for the East China Sea in References [1] and [2], the present paper proposes a more complete one, which is basically brought into line with Reference [3]. It is interesting to note that the computation results based on both the models mentioned above are the same in principle though different in detail. A comparison between numerical modeling and observations shows an agreement and the dynamics of circulation in the East China Sea reveals that the pattern of circulation is controlled by boundary force, water depth and ther-mohaline effect with the wind stress playing a minor role therein. 相似文献
72.
庄河市海洋产业空间布局研究 总被引:1,自引:0,他引:1
随着人口增长,资源减少以及陆域开发空间的缩小,海洋在全球生命支持系统的地位更加突出。本文以层次分析法和GIS为辅助工具,以地理学有关理论为指导,对庄河市海洋产业空间布局问题进行探讨。 相似文献
73.
74.
对渤海潮波系统的计算,我们分别采用二维有限差分方法、有限元方法进行了数值模拟,同时应用三维非线性潮波理论进行了数值计算,除计算潮流外,还计算了潮致余流。 相似文献
75.
本文对东太平洋海隆赤道地区北部和南部的9件玄武岩样品进行了详细的岩相学和主量、微量元素及Sr-Nd-Pb同位素分析研究,结果表明:MgO含量为7.32%~10.22%,Na_2O为3.03%~3.59%,K_2O为0.23%~0.57%,CaO为10.96%~12.39%,Al_2O_3为11.40%~13.76%,该区玄武岩均属于亚碱性玄武岩,具有MORB型的稀土及微量元素特点,原始岩浆均经历了橄榄石和斜长石的分离结晶。轻重稀土元素含量均较低,LREE/HREE比值为0.61~0.97,(La/Yb)N比值为0.72~1.76,(La/Sm)N比值为0.60~1.30,(Gd/Yb)N为0.99~1.16。Sr-Nd-Pb同位素特征更接近NMORB,其中,87Sr/86Sr和143 Nd/144 Nd比值更接近DM源区,而Pb的三种同位素比值要明显高于DM源区,更为接近EM源区。研究表明岩浆起源于尖晶石橄榄岩区,来源于较为亏损的地幔,NEPR玄武岩可能混有HIMU源区,SEPR玄武岩除了混合有HIMU成分外,可能还有少量的EMⅡ成分。 相似文献
76.
Copepod fecal pellets are ubiquitous throughout the oceans. Their production and export can represent a highly efficient pathway of carbon export. However, the role these fecal pellets play in carbon export in the Changjiang(Yangtze) River estuary is not well known. Two cruises were carried out in the Changjiang estuary in the spring and summer of 2013, during which time carbon biomass, production, and export of copepod fecal pellets were studied. Spring and summer fecal pellet carbon biomass ranged 0.30–1.01 mg C/m~3(mean=0.56±0.20 mg C/m~3) and 0.31–1.18 mg C/m~3(mean=0.64±0.24 mg C/m~3), respectively, significantly lower than phytoplankton. At most stations, fecal pellet carbon biomass was higher in surface or subsurface layers than deeper layers. Production rates ranged 0.65–1.49 pellets/(ind.?h)(mean=1.02±0.27 pellets/(ind.?h)) in spring and 0.62–1.34 pellets/(ind.?h)(mean=0.98±0.22 pellets/(ind.?h)) in summer, within the range reported in previous studies. Higher production rates of fecal pellets occurred at stations with higher chlorophyll a concentrations, and production rates of copepods of size 500–1 000 μm greater than copepods 1 000 μm during both cruises. The potential export flux of fecal pellets was slightly higher in summer(mean=68.95±14.37 mg C/(m~2 ?d)) than spring(mean=52.08±11.33 mg C/(m~2 ?d)) owing to higher summer copepod abundances. To our knowledge, this study is the first of its kind in the Changjiang estuary, and it confirms the significant role of copepod fecal pellets in local carbon export. 相似文献
77.
Seasonal variations in numerical abundance, cell diameter and population carbon biomass of the heterotrophic dinoflagellate Noctiluca scintillans were studied for 10 years from 2004 to 2013 in Jiaozhou Bay and adjacent coastal Yellow Sea, China, and their ecological functions were evaluated. In both areas, N. scintillans occurred throughout the year and demonstrated an essentially similar seasonality; the cell abundance increased rapidly from the winter minimum to an annual peak in late spring and early summer, and decreased gradually toward the autumn-winter minimum. The peak abundance differed by years, and there was no consistent trend in long-term numerical variations. The cell diameter also showed a seasonal fluctuation, being larger in spring and early summer than the other seasons. Estimated carbon biomass of N. scintillans population reached to a peak as high as 90.3 mg C/m~3, and occasionally exceed over phytoplankton and copepod biomass. Our results demonstrate that N. scintillans in northwestern Yellow Sea displays the seasonal phenology almost identical to the populations in other temperate regions, and play important trophic roles as a heterotroph to interact with sympatric phytoplankton and copepods. 相似文献
78.
测定了不同辐射强度的中波紫外线(UV-B)对潮间带海藻—孔石莼相对生长率、光合生理活性以及孢子萌发情况的影响。研究表明:UV-B抑制孔石莼的生长,随着辐射强度增加,抑制作用加强,同时UV-B也会抑制孢子萌发,4 kJ/m~2的辐射强度即可达到明显的抑制作用。此外,UV-B辐射使孔石莼叶绿素荧光参数(F_v/F_m、Y_Ⅰ、Y_Ⅱ)值降低,随着处理时间延长,孔石莼光合生理活性显著降低。相对于光系统Ⅰ,光系统Ⅱ对于UV-B造成的环境胁迫更为敏感。本研究为UV-B可能影响其他潮间带生物或生态系统的研究提供了理论基础。 相似文献
79.
应用高效液相色谱结合二极管阵列检测器分析技术,研究了西太平洋雅浦Y3海山区域2014年冬季浮游植物的光合色素组成。结果表明:100m以浅,玉米黄素(Zeax)是水柱中浓度最高的光合色素,浓度为22.64—84.31ng/L,叶绿素a(chl a)浓度在水柱中均值为(37±34) ng/L,在贫营养海区的数值范围内,水柱积分高值分布区与海山走向一致,二乙烯基叶绿素a(Dvchl a)和19''-丁酰氧岩藻黄素(19''BF)也是调查海区较高浓度的色素,在水柱中均值分别为(27±22)和(31±30) ng/L。其他色素新黄素(Neox)、叶黄素(Lute)、叶绿素b(chl b)、青绿素(Pras)平均水柱含量极低(<1.00ng/L)。通过CHEMTAX程序因子分析估算了浮游植物群落结构,调查区浮游植物群落以原绿球藻为优势藻,贡献率与环境因子不具有相关性,其次主要为蓝细菌和金藻,蓝细菌贡献率高值区分布在海山东南和东北侧0和30m水层,金藻贡献率高值区分布在75和100m水层,两者贡献率均与环境因子显著相关。 相似文献
80.
从长江经济带某在役石化场地采集了3个点位不同深度的土壤样品,测定了石油烃等污染物的含量和微生物的群落结构,以揭示污染物分布规律和微生物特征。结果显示,3个点位污染程度不同,但污染物含量均随深度先升高后降低,最高含量均出现在埋深4.0 m左右,即地下水位附近。土壤中C6-C9高达5 302 mg/kg,C10-C40高达625.6 mg/kg,芳烃高达455.2 mg/kg,卤代烃高达41.54 mg/kg。土壤微生物的丰富度和多样性随深度增加而降低,同一深度土壤微生物的丰富度和多样性随污染物含量增大而降低。门水平上Actinobacteria、Firmicutes和Spirochaetes的相对丰度和石油烃含量显著正相关(p<0.05),属水平上Streptomyces、SCADC1-2-3、Desulfitobacterium和Cryptanaerobacter的相对丰度和石油烃含量显著正相关(p<0.05)。 相似文献