全文获取类型
收费全文 | 216篇 |
免费 | 41篇 |
国内免费 | 24篇 |
专业分类
测绘学 | 76篇 |
大气科学 | 14篇 |
地球物理 | 35篇 |
地质学 | 108篇 |
海洋学 | 12篇 |
天文学 | 2篇 |
综合类 | 14篇 |
自然地理 | 20篇 |
出版年
2022年 | 3篇 |
2020年 | 3篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 8篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 16篇 |
2013年 | 11篇 |
2012年 | 12篇 |
2011年 | 10篇 |
2010年 | 10篇 |
2009年 | 7篇 |
2008年 | 11篇 |
2007年 | 10篇 |
2006年 | 20篇 |
2005年 | 19篇 |
2004年 | 7篇 |
2003年 | 13篇 |
2002年 | 10篇 |
2001年 | 24篇 |
2000年 | 10篇 |
1999年 | 15篇 |
1998年 | 9篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有281条查询结果,搜索用时 15 毫秒
51.
2018年伏秋汛期黄河流域上游持续来水,为保证2108-2019年度黄河流域凌汛期安全,黄河流域重点水库进行了大流量持续下泄。以2018年9月的实际数据为基准,通过对重点水库实际日均出入库调度情况,内蒙古河段的重点水文站实际日均流量过程和三个年份汛期大断面套绘成果对比分析研究,可以得出水库大流量持续下泄对内蒙古河段河道塑形能力起到了关键性作用,有效的提高了主槽过流能力,河段最小平滩流量得到一定的恢复,对下一步研究黄河流域河道过流能力提供了有利的数据支撑和参考价值。 相似文献
52.
青藏高原低涡活动对降水影响的统计分析 总被引:6,自引:0,他引:6
利用1998—2004年逐日08:00(北京时,下同)和20:00 500hPa高空图、日雨量和青藏高原低涡(下称高原低涡)切变线年鉴资料,统计分析了冬、夏半年不同生命史的高原低涡对我国和四川盆地东、西部降水的影响。结果表明,冬、夏半年高原低涡以东部涡占多数,6-10月有三分之一的东部涡能移出高原。冬半年高原低涡出现次数少,约占全年的五分之一,但也可造成高原及其周边地区的雨雪天气,特别是生命史超过36h以上的高原低涡有近半数可移出高原,造成高原区域暴雨雪,四川盆地中雨,半数可造成云南大雨雪或暴雨雪。夏半年,随着低涡生命史的增长,高原低涡影响高原及其周边地区和我国其他地区的降水范围和强度在增大,生命史超过60h以上的高原低涡可造成高原暴雨、甘肃中雨以上、四川盆地暴雨或大暴雨及云南大部分地区大雨以上的降水,每年都有1~5次可影响到华中、华东地区产生大雨以上的降水。100°E以东的高原低涡,不论是否移出,均可造成四川盆地中雨以上的降水。影响四川盆地降水的高原低涡以偏东路径为主,但东南路径影响更强。 相似文献
53.
54.
利用浙江省电力部门雷击跳闸数据、浙江省气象局闪电定位数据,统计分析了2007—2011年电力雷击跳闸事故与地闪数据之间的时空分布特点、雷击跳闸事故与地闪参数及距离之间的关系。结果表明:电力雷击跳闸事故与地闪数据的日分布和月分布均为单峰结构,相关系数分别为0.9905和0.9881;空间分布虽有一定对应,但并非显著相关;导致110kV、220kV及500kV输电线路雷击跳闸的地闪强度主要集中在90kA以下,并且500kV输电线路雷击跳闸对应的电流强度相对较小;地闪与雷击跳闸事故杆塔距离、地闪与雷击跳闸杆塔对应输电线路的距离均主要集中在2km以下。 相似文献
55.
针对因地基条件复杂或处理不当引起地基不均匀沉降而造成的建筑物倾斜,提出了注浆、抽水、掏土法,对建筑物进行纠偏加固处理,取得了良好的经济效益和社会效益。 相似文献
56.
Sabrina Scherzer Nina Gunnerud Berg Haakon Lein 《Norsk geografisk tidsskrift. Norwegian journal of geography》2020,74(3):152-164
ABSTRACT Despite much attention paid to the topic of community in academic literature and policy documents, there is a relative lack of knowledge about what laypersons perceive as a local community. Based on data from a national survey, the authors examine how c.1400 Norwegians conceptualized local community – lokalsamfunn in Norwegian. They reveal some of the linguistic and conceptual aspects of local community as a term, in addition to tendencies and patterns among the survey responses. The respondents’ conceptualizations contained references to lokalsamfunn variously as a geographical area, people and relations, activities and involvement, attachment to place and people, and provider of local goods and services. Their main emphasis was on lokalsamfunn as a spatial unit. However, the responses contained relatively few references to the relational aspects of lokalsamfunn. The authors conclude that a common, lay understanding may be that lokalsamfunn is a vaguely defined but limited geographical unit filled with people who to varying degrees know each other and interact. Concerning policymaking aimed at fostering communal well-being, the authors hold that any community-based programming requires intricate knowledge of the people who form the community, since without community interaction and a degree of social cohesion any envisioned programmes may not succeed. 相似文献
57.
58.
59.
60.
Differences in fluids origin, creation of overpressure and migration are compared for end member Neogene fold and thrust environments: the deepwater region offshore Brunei (shale detachment), and the onshore, arid Central Basin of Iran (salt detachment). Variations in overpressure mechanism arise from a) the availability of water trapped in pore-space during early burial (deepwater marine environment vs arid, continental environment), and b) the depth/temperature at which mechanical compaction becomes a secondary effect and chemical processes start to dominate overpressure development. Chemical reactions associated with smectite rich mud rocks in Iran occur shallow (∼1900 m, smectite to illite transformation) causing load-transfer related (moderate) overpressures, whereas mechanical compaction and inflationary overpressures dominate smectite poor mud rocks offshore Brunei. The basal detachment in deepwater Brunei generally lies below temperatures of about 150 °C, where chemical processes and metagenesis are inferred to drive overpressure development. Overall the deepwater Brunei system is very water rich, and multiple opportunities for overpressure generation and fluid leakage have occurred throughout the growth of the anticlines. The result is a wide variety of fluid migration pathways and structures from deep to shallow levels (particularly mud dykes, sills, laccoliths, volcanoes and pipes, fluid escape pipes, crestal normal faults, thrust faults) and widespread inflationary-type overpressure. In the Central Basin the near surface environment is water limited. Mechanical and chemical compaction led to moderate overpressure development above the Upper Red Formation evaporites. Only below thick Early Miocene evaporites have near lithostatic overpressures developed in carbonates and marls affected by a wide range of overpressure mechanisms. Fluid leakage episodes across the evaporites have either been very few or absent in most areas. Locations where leakage can episodically occur (e.g. detaching thrusts, deep normal faults, salt welds) are sparse. However, in both Iran and Brunei crestal normal faults play an important role in the transmission of fluids in the upper regions of folds. 相似文献