全文获取类型
收费全文 | 745篇 |
免费 | 207篇 |
国内免费 | 551篇 |
专业分类
测绘学 | 23篇 |
大气科学 | 74篇 |
地球物理 | 195篇 |
地质学 | 928篇 |
海洋学 | 138篇 |
天文学 | 27篇 |
综合类 | 80篇 |
自然地理 | 38篇 |
出版年
2018年 | 1篇 |
2015年 | 6篇 |
2013年 | 5篇 |
2011年 | 206篇 |
2010年 | 132篇 |
2009年 | 185篇 |
2008年 | 27篇 |
2007年 | 77篇 |
2006年 | 116篇 |
2005年 | 144篇 |
2004年 | 208篇 |
2003年 | 108篇 |
2002年 | 73篇 |
2001年 | 62篇 |
2000年 | 26篇 |
1999年 | 24篇 |
1998年 | 10篇 |
1997年 | 12篇 |
1996年 | 2篇 |
1995年 | 9篇 |
1994年 | 2篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 7篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1950年 | 2篇 |
1943年 | 2篇 |
1940年 | 2篇 |
1937年 | 3篇 |
1934年 | 5篇 |
1933年 | 3篇 |
1931年 | 1篇 |
1928年 | 2篇 |
1926年 | 1篇 |
排序方式: 共有1503条查询结果,搜索用时 956 毫秒
171.
JI YouLiang ZHOU Yong KUANG Jun WAN Lu ZHANG Rui & LU ChunHong State Key Laboratory of Petroleum Resource Prospecting China University of Petroleum Beijing China Xinjiang Oil Field Urumqi 《中国科学:地球科学(英文版)》2010,(6)
The Chepaizi-Mosuowan paleo-uplift is a large-scale uplift stretching across the Junggar Basin formed during the Yanshanian. It has experienced four evolutionary stages: the initial forming stage (J1), the intense development stage (J2+3), the waning and burial stage (K-E), and the tilting and extinction stage (N-Q). The most intense period of activities is the Middle Jurassic. Dur-ing the Early Jurassic, the Chepaizi-Mosuowan paleo-structure was a low amplitude uplift. Because of the subsequent strong upli... 相似文献
172.
YUE Ping NIU ShengJie HU YinQiao & ZHANG Qiang Key Laboratory of Arid Climate Change Reducing Disaster of Gansu Province Key Laboratory of Arid Climate Change Reducing Disaster of CMA 《中国科学:地球科学(英文版)》2010,(5)
Macroscopic reason for the development of turbulences in fluid is the conjunction action of velocity and temperature shears. We use the 2008 spring flux observations in the surface layer over Inner Mongolian grassland, obtain the similarity functions of turbulent intensity under different stratification stability conditions, and calculate the clear day turbulent intensity in the spring, which is then analyzed and compared with the observed values of turbulent intensity. The results show that in the Inner Mo... 相似文献
173.
In 2008,a green tide broke out before the sailing competition of the 29th Olympic Games in Qingdao.The causative species was determined to be Enteromorpha prolifera (Ulva prolifera O.F.Müller),a familiar green macroalga along the coastline of China.Rapid accumulation of a large biomass of floating U.prolifera prompted research on different aspects of this species.In this study,we constructed a nonnormalized cDNA library from the thalli of U.prolifera and acquired 10 072 high-quality expressed sequence tags ... 相似文献
174.
We cultured different-sized fractions of dominant phytoplankton species,Skeletonema costatum,Chaetoceros curvisetus,and Thalassiosira nordenski ldii,collected in different sea areas in various seasons,and measured and compared their C,N,P,Si contents.The N content of these species is similar,while the C,P,and Si contents of S.costatum from eutrophic Changjiang (Yangtze River) estuary are higher than those from Jiaozhou Bay (JZB),particularly the content of Si.The C,N,P,and Si contents of cultured phytoplank... 相似文献
175.
针对高应力软岩公路隧道的特点,对湖北宜巴高速公路峡口隧道开展了地应力测试、隧洞收敛下沉、接触应力、结构受力等项目的监测工作。地应力测试结果表明,虽然隧洞埋深不大,但由于构造应力的存在,仍属于高地应力区。施工监测结果表明,高应力软岩隧道变形与结构受力具有明显的时空效应,与开挖方式、工作面距离以及支护时机密切相关。由于隧洞围岩软弱破碎,加之处于高应力作用下,在工作面通过后,岩体产生持续性的流变变形,导致隧洞产生挤压大变形和结构受力的持续增加,达到支护结构强度极限,最终导致围岩失稳和支护体系的失效。基于上述研究成果,提出了相应的高应力软岩大变形支护设计对策。研究成果为高应力软岩隧道变形与结构受力的时空效应性提供了监测数据支持,为峡口隧道的施工和支护设计提供了依据,对我国西部其他高应力软岩公路隧道的建设具有借鉴意义 相似文献
176.
LIU JiPing State Key Laboratory of Numerical Modeling for Atmospheric Sciences Geophysical Fluid Dynamics 《中国科学:地球科学(英文版)》2010,(6)
The impacts of the spatiotemporal variations of sea ice salinity on sea ice and ocean characteristics have not been studied in detail, as the existing climate models neglect or misrepresent this process. To address this issue, this paper formulated a parameterization with more realistic sea ice salinity budget, and examined the sensitivity of sea ice and ocean simulations to the ice salinity variations and associated salt flux into the ocean using a coupled global climate model. Results show that the inclus... 相似文献
177.
Conductivity structure and rheological property of lithosphere in Southern Tibet inferred from super-broadband magnetotelluric sounding 总被引:2,自引:0,他引:2
To understand deep lithosphere structure beneath the Qinghai-Tibet Plateau more comprehensively and objectively and to explore important scientific issues,such as characteristics of plateau lithospheric deformation,state of strain,thermal structure,plate (or terrane) movement,and crust-mantle rheology,it is necessary to research the variation of crust-mantle electrical structure in the east-west direction in every geological unit.For this purpose,six super-broadband magnetotelluric (MT) sounding profiles ha... 相似文献
178.
Climate variability recorded by n-alkanes of paleolake sediment in Qaidam Basin on the northeast Tibetan Plateau in late MIS3 总被引:1,自引:0,他引:1
PU Yang ZHANG HuCai LEI GuoLiang CHANG FengQin YANG MingSheng ZHANG WenXiang LEI YanBin YANG LunQing & PANG YouZhi State Key Laboratory of Lake Science Environment Nanjing Institute of Geography Limnology Chinese Academy of Sciences Nanjing China Graduate University of Chinese Academy of Sciences Beijing Key Laboratory of Boyang Lake MOE School of Environmental Chemical Engineering Nanchang University Nanchang 《中国科学:地球科学(英文版)》2010,(6)
Here we combine n-alkanes preserved in a shell bar section from Qarhan paleolake, Qaidam Basin with the other sedimentary proxies to elucidate the lake evolution process during the period 39.7 to 17.5 14C ka BP (calibrated age ranges from 43.5 to 22.4 cal. ka BP). In different stages, the n-alkane homologues exhibited different distribution modes indicative of variations in the surrounding vegetation and the hydrologic condition of the lake. The n-alkanes proxies (CPIh, ACLh, Paq) have the same trends as th... 相似文献
179.
180.