全文获取类型
收费全文 | 2643篇 |
免费 | 929篇 |
国内免费 | 947篇 |
专业分类
测绘学 | 33篇 |
大气科学 | 160篇 |
地球物理 | 396篇 |
地质学 | 2354篇 |
海洋学 | 306篇 |
天文学 | 17篇 |
综合类 | 827篇 |
自然地理 | 426篇 |
出版年
2024年 | 19篇 |
2023年 | 60篇 |
2022年 | 95篇 |
2021年 | 124篇 |
2020年 | 157篇 |
2019年 | 156篇 |
2018年 | 120篇 |
2017年 | 159篇 |
2016年 | 131篇 |
2015年 | 165篇 |
2014年 | 278篇 |
2013年 | 213篇 |
2012年 | 232篇 |
2011年 | 212篇 |
2010年 | 225篇 |
2009年 | 183篇 |
2008年 | 233篇 |
2007年 | 207篇 |
2006年 | 188篇 |
2005年 | 191篇 |
2004年 | 136篇 |
2003年 | 128篇 |
2002年 | 97篇 |
2001年 | 125篇 |
2000年 | 124篇 |
1999年 | 111篇 |
1998年 | 77篇 |
1997年 | 72篇 |
1996年 | 53篇 |
1995年 | 37篇 |
1994年 | 48篇 |
1993年 | 30篇 |
1992年 | 34篇 |
1991年 | 20篇 |
1990年 | 20篇 |
1989年 | 11篇 |
1988年 | 14篇 |
1987年 | 17篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有4519条查询结果,搜索用时 156 毫秒
551.
Sridhar D. IYER 《《地质学报》英文版》2005,79(1):77-86
1 IntroductionMetalliferous sediments and mounds occur in all majortectonic settings in the oceans (e.g., the Galapagos Rift,East Pacific Rise (EPR), Bauer Deep and Central Basin ofthe Pacific; Heath and Dymond, 1977). Further, massivesulphide deposits and high-temperature vents have beenreported along the mid-ocean ridges (MOR). In the IndianOcean, an inactive hydrothermal field and a hydrothermalplume site have been discovered along the Central IndianRidge (CIR). The SONNE Hydro… 相似文献
552.
山东春季降水的时空变化特征分析 总被引:20,自引:4,他引:16
根据山东省81个地面站1961-1998年共38年的降水资料,应用自然正交函数展开(EOF)方法,分析了山东省38年春季月、季降水量的时空变化特征。根据降水方差累积贡献率和空间分布特征,指出前3个典型场基本能反映山东省春季季降水分布的主要特征,其贡献率高达81.30%,据此得出山东省春季降水分布类型:总体一致型、东南-西北差异型和西南-东北差异型。山东春季降水空间分布可分为4个区,南部区:日照、临沂、枣庄及济宁;半岛区:烟台、威海、青岛和潍坊东部;西部区:荷泽、聊城;北部区:德州、滨州、东营、济南、泰安、莱芜、淄博和潍坊西部。同旱(涝)是山东春季各月降水的基本型。山东春季易出现干旱,春季降水存在明显的年际变化,有4.8~6年的振荡周期。 相似文献
553.
554.
鲁西隆起区奥陶系碳酸盐岩成岩作用及其对储集性的控制作用 总被引:13,自引:5,他引:8
以鲁西隆起区奥陶系碳酸盐岩沉积旋回与不整合面分析为基础, 应用薄片、铸体和阴极发光等室内分析技术, 对其成岩作用、成岩序列、孔隙演化及其特征进行了详细研究。研究区的成岩作用分为两类: 建设性成岩作用和破坏性成岩作用, 前者包括白云石化、压溶、去石膏化、溶蚀和破裂等作用; 后者以重结晶、胶结、压实、硅化和充填作用为主。奥陶系碳酸盐岩经历了多期次和多种类型的成岩作用演化, 与马家沟组相比, 三山子组多经历了一次其沉积后的短期表生和随后的埋藏作用。三山子组白云岩、马家沟组东黄山段、土峪段和阁庄段粉细晶白云岩以及八陡段不整合面以下的溶蚀角砾岩段发育次生孔洞缝系统, 是较为有利的储集层段。 相似文献
555.
556.
鲁西北地区土地现实生产力调查与估算 总被引:3,自引:0,他引:3
以鲁西北地区县级1∶5万土壤类型图图斑作为基础评价单元,根据农户现有的投入水平,采用“调查法”模拟分析农业土地资源的现实生产力,并与统计资料和“机制法”模型模拟结果进行对比分析。研究结果表明,现实投入水平下鲁西北地区夏玉米单产略高于冬小麦单产,对冬小麦的投入从整体上来看相当于中等投入,但又存在着区域差异。对夏玉米的投入具有南北向的差异,由南到北投入水平逐渐降低。鲁西北地区土地现实生产力以宁津县最高,庆云县最低,与“机制法”模型模拟结果比较,各县市之间土地生产潜力差距较大。由此可以说明,各县市土壤质量本身对土地年生产力的大小起着重要作用,进一步证明“调查法”能充分反映土壤在土地综合性质中的主要作用。 相似文献
557.
I. K. Kozakov T. I. Kirnozova Yu. V. Plotkina 《Stratigraphy and Geological Correlation》2009,17(1):36-42
In South Mongolia, the Hercynian structures of a linear collisional thrust-and-fold zone formed in the Carboniferous are bounded by the Caledonides of Central and North Mongolia on the north, being truncated on the south by the Indosinides of the Inner Mongolia. Tectonic sheets of the Caledonides-Hercynides junction zone confined to southern flank of the Mongolian-Gobi Altai are composed of high-gradient metamorphites of the South Altai metamorphic belt. The belt of these rocks traceable northwestward in China and eastern Kazakhstan delineates margin of the North Asian Caledonian paleocontinent. According to results of the previous geochronological study, the high- and low-gradient metamorphic rocks of the belt originated respectively 385 and 360–370 Ma ago. However, tectonic position of crystalline rock sequences, which have not been dated, remains unclear. Geochronological interval postulated for these rocks is very broad, ranging from the Early Precambrian to the Devonian. Dating results obtained in this work for detrital zircons from siliciclastic metasediments of the Bodonchin tectonic sheet of the belt show that their protoliths accumulated during the time span of 460–390 Ma (Late Ordovician-Early Devonian) on a passive continental margin. Transformation of the latter into active continental margin took place in the Early Devonian, when development of the Siberian subduction zone resulted in formation of the South Altai metamorphic belt at deep crustal levels of the Caledonian paleocontinent. 相似文献
558.
Dextral‐Slip Thrust Faulting and Seismic Events of the Ms 8.0 Wenchuan Earthquake,Longmenshan Mountains,Eastern Margin of the Tibetan Plateau 总被引:1,自引:1,他引:0
Abstract: Dextral-slip thrust movement of the Songpan-Garzê terrain over the Sichuan block caused the Ms 8.0 Wenchuan earthquake of May 12, 2008 and offset the Central Longmenshan Fault (CLF) along a distance of ~250 km. Displacement along the CLF changes from Yingxiu to Qingchuan. The total oblique slip of up to 7.6 m in Yingxiu near the epicenter of the earthquake, decreases northeastward to 5.3 m, 6.6 m, 4.4 m, 2.5 m and 1.1 m in Hongkou, Beichuan, Pingtong, Nanba and Qingchuan, respectively. This offset apparently occurred during a sequence of four reported seismic events, EQ1–EQ4, which were identified by seismic inversion of the source mechanism. These events occurred in rapid succession as the fault break propagated northeastward during the earthquake. Variations in the plunge of slickensides along the CLF appear to match these events. The Mw 7.5 EQ1 event occurred during the first 0–10 s along the Yingxiu-Hongkou section of the CLF and is characterized by 1.7 m vertical slip and vertical slickensides. The Mw 8.0 EQ2 event, which occurred during the next 10–42 s along the Yingxiu-Yanziyan section of the CLF, is marked by major dextral-slip with minor thrust and slickensides plunging 25°–35° southwestward. The Mw 7.5 EQ3 event occurred during the following 42–60 s and resulted in dextral-slip and slickensides plunging 10° southwestward in Beichuan and plunging 73° southwestward in Hongkou. The Mw 7.7 EQ4 event, which occurred during the final 60–95 s along the Beichuan-Qingchuan section of the CLF, is characterized by nearly equal values of dextral and vertical slips with slickensides plunging 45°–50° southwestward. These seismic events match and evidently controlled the concentrations of landslide dams caused by the Wenchuan earthquake in Longmenshan Mountains. 相似文献
559.
560.