全文获取类型
收费全文 | 5326篇 |
免费 | 1004篇 |
国内免费 | 1383篇 |
专业分类
测绘学 | 378篇 |
大气科学 | 977篇 |
地球物理 | 1282篇 |
地质学 | 2779篇 |
海洋学 | 803篇 |
天文学 | 250篇 |
综合类 | 518篇 |
自然地理 | 726篇 |
出版年
2024年 | 30篇 |
2023年 | 98篇 |
2022年 | 288篇 |
2021年 | 326篇 |
2020年 | 292篇 |
2019年 | 360篇 |
2018年 | 340篇 |
2017年 | 305篇 |
2016年 | 324篇 |
2015年 | 278篇 |
2014年 | 338篇 |
2013年 | 380篇 |
2012年 | 302篇 |
2011年 | 319篇 |
2010年 | 297篇 |
2009年 | 339篇 |
2008年 | 282篇 |
2007年 | 251篇 |
2006年 | 217篇 |
2005年 | 165篇 |
2004年 | 135篇 |
2003年 | 155篇 |
2002年 | 155篇 |
2001年 | 164篇 |
2000年 | 176篇 |
1999年 | 187篇 |
1998年 | 180篇 |
1997年 | 150篇 |
1996年 | 138篇 |
1995年 | 123篇 |
1994年 | 99篇 |
1993年 | 99篇 |
1992年 | 94篇 |
1991年 | 66篇 |
1990年 | 53篇 |
1989年 | 44篇 |
1988年 | 34篇 |
1987年 | 20篇 |
1986年 | 18篇 |
1985年 | 12篇 |
1984年 | 11篇 |
1983年 | 16篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 8篇 |
1976年 | 3篇 |
1958年 | 5篇 |
排序方式: 共有7713条查询结果,搜索用时 15 毫秒
101.
Introduction Receiver function has been extensively applied in studying S wave velocity of crust and up-per mantle for about 20 years (Owens, et al, 1987; LIU, et al, 1996), which is a time series ob-tained by the deconvolution of vertical component from horizontal component for teleseismic P waveform. Receiver function represents the teleseismic P plane wave response of crust and upper mantle beneath seismic station, from which the source and propagation effects are removed. Receiver funct… 相似文献
102.
羌塘岩带碰撞后超钾质火山岩地球化学特征及成因探讨 总被引:1,自引:0,他引:1
羌塘超钾质火山岩为板块碰撞后的产物,地球化学特征表明,其同时具有板内火山岩和俯冲带岛弧火山岩的双重地球化学特性。化学组成上富含轻稀土和大离子亲石元素而亏损Cr、Ni等相容元素。在成因上受分离结晶作用和源区混合作用共同制约。源区为受古俯冲上地壳物质和下地幔上升流体交代混合的EMII型富集地幔端元,可能富含角闪石和金云母等矿物。 相似文献
103.
104.
Ultrahigh-pressure metamorphism in the forbidden zone: the Xugou garnet peridotite, Sulu terrane, eastern China 总被引:21,自引:3,他引:21
The Xugou garnet peridotite body of the southern Sulu ultrahigh‐pressure (UHP) terrane is enclosed in felsic gneiss, bounded by faults, and consists of harzburgite and lenses of garnet clinopyroxenite and eclogite. The peridotite is composed of variable amounts of olivine (Fo91), enstatite (En92?93), garnet (Alm20?23Prp53?58Knr6?9Grs12?18), diopside and rare chromite. The ultramafic protolith has a depleted residual mantle composition, indicated by a high‐Mg number, very low CaO, Al2O3 and total REE contents compared to primary mantle and other Sulu peridotites. Most garnet (Prp44?58) clinopyroxenites are foliated. Except for rare kyanite‐bearing eclogitic bands, most eclogites contain a simple assemblage of garnet (Alm29?34Prp32?50Grs15?39) + omphacite (Jd24?36) + minor rutile. Clinopyroxenite and eclogite exhibit LREE‐depleted and LREE‐enriched patterns, respectively, but both have flat HREE patterns. Normalized La, Sm and Yb contents indicate that both eclogite and garnet clinopyroxenite formed by high‐pressure crystal accumulation (+ variable trapped melt) from melts resulting from two‐stage partial melting of a mantle source. Recrystallized textures and P–T estimates of 780–870 °C, 5–7 GPa and a metamorphic age of 231 ± 11 Ma indicate that both mafic and ultramafic protoliths experienced Triassic UHP metamorphism in the P–T forbidden zone with an extremely low thermal gradient (< 5 °C km?1), and multistage retrograde recrystallization during exhumation. Develop of prehnite veins in clinopyroxenite, eclogite, felsic blocks and country rock gneiss, and replacements of eclogitic minerals by prehnite, albite, white mica, and K‐feldspar indicate low‐temperature metasomatism. 相似文献
105.
106.
WangShicheng YeShuisheng ZhouDongdai 《中国地质大学学报(英文版)》2003,14(3):207-214
Metallogenic prognosis of synthetic information uses the geological body and the miaeral resource body as a statistical unit to interpret synthetically the information of geology, geophysics, geo-chemistry and remote sensing from the evolution of geology and puts all the information into one entire system by drawing up digitalized interpretation maps of the synthetic information. On such basis, differ-ent grades and types of mineral resource prospecting models and predictive models of synthetic informa-tion can be established. Hence, a new integrated prediction system will be formed of metallogenic prog-nosis (qualitative prediction), mineral resources statistic prediction (determining targets) and mlaeral resources prediction (determining resources amount). 相似文献
107.
During the whole 20th century in China, especially the latest 50 years, we have gotten much geological information about geological mapping, geophysics, geochemistry, mineral exploration,remote sensing, environmental geology, hydrogeology, engineering geology and oceanic geology etc. by our geologists and explorers. All the information has been accmnulated and can be used as a dcision-making foundation for the future plan of geological survey. The spatial database of geological survey ex-tents has been established by using computer technology. The database contained all kinds of exploration sections and collected about 160 000 records in this database. This paper introduces the data construc-tion ,contents and applying systemof this database, and trys to let people know what kinds of geological survey were finished, when the exploration were carried out, and how and where you can get this infor-mation. 相似文献
108.
统计1965年以来影响韶关的热带气旋发现,韶关出现暴雨不仅与热带气旋的路径、强度有关,而且与大气层结稳定度或冷空气的相互作用密切相关。由此结合实况、应用数值预报产品来制作热带气旋暴雨24小时预报。 相似文献
109.
110.
通过对1975~1998年北京动物园动物发病率的统计分析,揭示了不同动物发病率的年变化特征和长期变化趋势,并分季节进行了发病率与气象因子的相关分析,发现冬季兽类发病率、秋季禽类发病率与同期气象因子相关较好,总体看春、夏季动物发病率与气象因子的关系不明显。 相似文献