全文获取类型
收费全文 | 1524篇 |
免费 | 197篇 |
国内免费 | 290篇 |
专业分类
测绘学 | 40篇 |
大气科学 | 27篇 |
地球物理 | 55篇 |
地质学 | 1315篇 |
海洋学 | 25篇 |
综合类 | 94篇 |
自然地理 | 455篇 |
出版年
2024年 | 8篇 |
2023年 | 19篇 |
2022年 | 58篇 |
2021年 | 58篇 |
2020年 | 48篇 |
2019年 | 61篇 |
2018年 | 40篇 |
2017年 | 51篇 |
2016年 | 53篇 |
2015年 | 63篇 |
2014年 | 102篇 |
2013年 | 85篇 |
2012年 | 115篇 |
2011年 | 124篇 |
2010年 | 109篇 |
2009年 | 121篇 |
2008年 | 132篇 |
2007年 | 113篇 |
2006年 | 120篇 |
2005年 | 93篇 |
2004年 | 84篇 |
2003年 | 74篇 |
2002年 | 45篇 |
2001年 | 34篇 |
2000年 | 28篇 |
1999年 | 30篇 |
1998年 | 20篇 |
1997年 | 19篇 |
1996年 | 16篇 |
1995年 | 14篇 |
1994年 | 21篇 |
1993年 | 11篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 19篇 |
1989年 | 6篇 |
1988年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有2011条查询结果,搜索用时 16 毫秒
101.
在323国道施工过程中,由于发生了西江大滑坡,给施工进度带来影响。本文对西江大滑坡产生的原因进行了分析,并提出了具体的处理方案,对以后类似问题的处理具有一定的参考价值。 相似文献
102.
The Apuseni Mountains constitute one of the most interesting parts of the Carpathians in terms of landscape, biodiversity
and culture. Yet dislocations are now severe and there are development threats which also require a significant response.
On the one hand there are some severe pollution problems associated with mining areas developed in the communist period which
require remedial action and the cases of Roşia Montana and Zlatna are discussed. On the other hand, there are forest and pasture
zones – especially the Padiş Plateau – which are coming under heavy pressure from farmers seeking to enhance their incomes
following the decline of mining and manufacturing which has left many households without salaries. At the same time, tourist
pressure is growing. Actions are already being taken to limit pollution damage and develop sustainable landuse practices.
There is a national park project linked with nature reserves comprising picturesque landscapes, a rare flora and fauna and
distinct geological and palaeotological formations (including fossil ice). There are major tourist attractions and with proper
management they could become part of a development programme of the countryside. However it is essential that all stakeholders
adopt sustainable practices and this means that official programmes – including the future national park authority administration's
work in environment protection and tourism management – are backed up by Environmental Non-Governmental Organisations (ENGOs).
The paper reviews their diverse activities and concludes that they are making a very substantial contribution in ensuring
that the potentials of isolated regions can be utilised in a manner consistent with nature conservation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
103.
县内土地面积36.49万hm2,坡耕地面积3.44万hm2.坡耕地粮食年产4500-6500kg/km2.低产原因是土层瘠薄,缺土水肥.采取的综合治理措施有:建设农田基础设施,实行生物-工程措施,推行分带轮作三熟制等.由此粮食年产达11000—12500kg/hm2. 相似文献
104.
I.EnvironmeotaICharacterishcsofChangliCountyChangliCoLmtyislocatedinthenortheastermendoftheNorthChinaPlain,nexttoBohaiSeaontheeastandthesouthemendofYanshanMountainsontl1enortl1.Luani1emverWhichrunsthroughthecouotyforn1sthewestemandsouthemboundaryoftitiscoastalcounty.ThenorthempartofthecoUnyishillywithaverageheigltrrangingfrom5oto5Oom,andmostportionintheeastemandsouflempartislocatedonthealluvialplainofLuani1eandYirunarivers,inclilungfromnorthwesttosoutieastwiil1heighrangingfrom2to3m.Tl1… 相似文献
106.
107.
东吉庄矿泉水是1989年由地质矿产部环境管理司会同卫生部、轻工业部等有关单位的国家饮用天然矿泉水技术评审组鉴定通过,符合GB8537-87的国家标准要求,属含锶重碳酸镁·钙·钠型低矿化度中性饮用天然矿泉水,已于同年建立了奥玉饮料厂,生产瓶装矿泉水及奥玉饮料。为了保护矿泉水资源免遭环境污染,对该矿泉水水源地进行了水源地保护规划。 相似文献
108.
王敏 《华北地质矿产杂志》1995,10(4):510-514
围场牌楼御圣矿泉水出露于侏罗系张家口组凝灰岩、安山岩中,属偏硅酸、锶复合型矿泉水,其成因是含偏硅酸和锶的岩石经地下水深循环作用,长期溶滤围岩,使偏硅酸、锶不断富集的结果,除含偏硅酸、锶外,还含有有益于人体健康的微量元素。该矿泉水水量充沛,动态稳定,水质良好。 相似文献
109.
110.
Wang Wenli Institute of Natural History Beijing Natural History Museum Yang Zunyi 《《地质学报》英文版》1993,67(3)
A new insect family Liaoximordellidae (fam. nov.) has been named for a well-preserved specimen which was collected from the Upper Jurassic outcropping west of Daxinfangzi Village, Lingyuan County, Liaoning Province. The specimen can not be put into Mordellidae or Praemordellidae because it possesses some original and intermediate characters in morphology. It serves the study of mordellid evolution. Besides, the fossil group associated with the insect is important for the stratigraphic division of the Mesozoic in western Liaoning. 相似文献