全文获取类型
收费全文 | 7638篇 |
免费 | 1493篇 |
国内免费 | 1757篇 |
专业分类
测绘学 | 402篇 |
大气科学 | 1736篇 |
地球物理 | 2156篇 |
地质学 | 3707篇 |
海洋学 | 792篇 |
天文学 | 358篇 |
综合类 | 749篇 |
自然地理 | 988篇 |
出版年
2024年 | 28篇 |
2023年 | 137篇 |
2022年 | 393篇 |
2021年 | 432篇 |
2020年 | 368篇 |
2019年 | 401篇 |
2018年 | 492篇 |
2017年 | 439篇 |
2016年 | 477篇 |
2015年 | 375篇 |
2014年 | 461篇 |
2013年 | 452篇 |
2012年 | 464篇 |
2011年 | 431篇 |
2010年 | 438篇 |
2009年 | 422篇 |
2008年 | 386篇 |
2007年 | 391篇 |
2006年 | 258篇 |
2005年 | 264篇 |
2004年 | 225篇 |
2003年 | 181篇 |
2002年 | 213篇 |
2001年 | 218篇 |
2000年 | 251篇 |
1999年 | 369篇 |
1998年 | 251篇 |
1997年 | 274篇 |
1996年 | 245篇 |
1995年 | 223篇 |
1994年 | 161篇 |
1993年 | 183篇 |
1992年 | 118篇 |
1991年 | 88篇 |
1990年 | 52篇 |
1989年 | 72篇 |
1988年 | 53篇 |
1987年 | 31篇 |
1986年 | 32篇 |
1985年 | 23篇 |
1984年 | 23篇 |
1983年 | 13篇 |
1982年 | 17篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1958年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
11.
情境教学是培养学生核心素养的重要教学方法,本文提出了情境教学的课堂评价原则:情境具有真实性、情境与教学目标具有关联性、情境应划分水平。同时提出从情境的结构和关系、解决情境中的问题所涉及地理要素的数量及其关联程度两个角度分别对情境水平进行划分,并结合“资源枯竭型城市的发展方向”课例,提出目前情境教学中存在的问题及教学改进建议。 相似文献
12.
ZHANGPing-yu MAYan-ji YUZhen-han 《中国地理科学(英文版)》2002,12(4):315-320
Manzhouli is the largest land port city on the Sino-Russia border, transit cargo through the land port amount-ed to 5.95 million tons, transit tourists were 304 500 in 2000. It stands at the joint place of China, Mongolia and Russi-a, faces to Siberia area of Russia, receives direct support from the Northeast China and Bohai Sea Rim Area, and possess-es priorities in geographical location, land port infrastructure, water resources, coal resources, tourist resources andgreat potentiality in economic cooperation with Russia. The future urban function is a key port on the First Eurasia Continen-tal Bridge. Manzhouli Port will keep its first place between China and Russia land transport, and it is forecasted that thetransit amount through Manzhouli Port will go up to 10 million tons in 2005 and 20 million tons in 2010. It will be construct-ed to be a trade center of the peripheral area extending to Russia and Mongolia, a key export-oriented processing industri-al zone supported by industries such as export processing industries, export agriculture, trade services, technology trad-ing and the other service industries. It keeps being a well-known touring city for trade, shopping, sightseeing, vocation,local food, recreation and cultural events. To build Manzhouli Export Processing Industry Zone will improve city econom-ic structure, and the main sectors are organic food processing, livestock products processing, garment and furniture indus-try. Moreover, Manzhouli Export Processing Industry Zone will eventually be upgraded to be a border free trade zone.The city functional transition will inevitably affect urban spatial restructure and its expansion. The city space transforma-tion will develop as such: one development axis of No. 301 highway paralleling with Bin - Zhou(Harbin - Manzhouli) rail-way which cuts through central part of Manzhouli City, and links Zhalainuocr District with central city; three urban unitsincluding central city, Zhalainuocr District and Manzhouli Interchange Trade Zone; cohesion with Aoerjin and Cuogangpastures; regional dual-nuclei structure of Hailaer City and Manhzouli City; and the Manzhouli-Zabaykalsk Free TradeZone. 相似文献
13.
A wide-field time-series CCD photometric survey of variable stars in the field of the open cluster NGC 2168 was carried out using the BATC Schmidt telescope. In total 13 new variable stars are discovered with three W UMa systems, one EA type and two EB type eclipsing binaries (one of them could be a W UMa system), and seven pulsating stars including three candidates of δScuti stars. 相似文献
14.
15.
青藏块体东北缘断层形变与中强地震 总被引:7,自引:4,他引:3
对祁连山-海原断裂带近期断层形变特征进行了初步研究,发现多场地,大范围的断层活动异常是中等强度地震发生的显著背景,并且往往与大陆地震活动的阶段性总体状况相呼应;区域形变存在明显的特征量,包括特征形态和特征时间,同一场地在不同地震前的异常特征具有重复性,但会受到背景差异显著的不同地震的影响,目前形变状况表明研究区仍具有发生中强地震的地壳运动背景。 相似文献
16.
HUXue-lian CHENGCheng-qi WUDe-wen MAAi-nai 《中国地理科学(英文版)》2003,13(1):84-90
Based on the analysis of the development of GIS technology and application,this paper brought forward the concept of GoGIS,namely Cooperative GIS ,CoGIS is GIS facing group-users and supporting human-human interaction,which makes it differ from the former GISs,Then,the characteristics of general Computer Spport Cooperative Work (CSCW)applications and the complexity of Geographic Information Science were analyzed,and the conclusion the CoGIS was not a simple GIS layer on CSCW was reached,Further,this paper gaver the hierarchical architecture of CoGIS,and analyzed the coperative platform in detail from the following:1)basic elements;2) collaboration patterns;3) cooperation control mechanism;4) synchronization mechanism;5) security and 6) group communication and so on.With those,the problems about GIS applications are discussed,such as 1)distributed multi-source GIS information and knowledge sharing platform;2)the fusion and visualization of GIS information;3)virtual reality cooperative modeling;4) dymamic simulation;5)expert system and 6) decision-making.Finally,this paper analyzed CoGIS application mode in brief. 相似文献
17.
An elastoplastic model for sands is presented in this paper, which can describe stress–strain behaviour dependent on mean effective stress level and void ratio. The main features of the proposed model are: (a) a new state parameter, which is dependent on the initial void ratio and initial mean stress, is proposed and applied to the yield function in order to predict the plastic deformation for very loose sands; and (b) another new state parameter, which is used to determine the peak strength and describe the critical state behaviour of sands during shearing, is proposed in order to predict simply negative/positive dilatancy and the hardening/softening behaviour of medium or dense sands. In addition, the proposed model can also predict the stress–strain behaviour of sands under three-dimensional stress conditions by using a transformed stress tensor instead of ordinary stress tensor. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
18.
19.
The dunes in estuary of Tumen River in China lie to the area between the Jiushaping and Fangchuan in the left bank of Tumen River (Fig.1). The dis-tance is about 15~20 km between the dunes and the coast. It ranges from China to D. P. R. Korea and Russia. The range of the height of dunes is about 15~20 m and the width is 100~200 m. By the re-connaissance, we protracted 9 section planes of the dunes and collected 40 sand samples of the dunes, and identified the sedimentary environment … 相似文献
20.
本文讨论了彗星中尘埃粒子的充电机制 ,带电特性和平衡电势的变化规律 ,分析了彗星尘埃的破碎特性和临界半径 ,得出了很有意义的结果 相似文献