全文获取类型
收费全文 | 137篇 |
免费 | 13篇 |
国内免费 | 29篇 |
专业分类
测绘学 | 7篇 |
大气科学 | 4篇 |
地球物理 | 18篇 |
地质学 | 15篇 |
海洋学 | 54篇 |
天文学 | 1篇 |
综合类 | 25篇 |
自然地理 | 55篇 |
出版年
2024年 | 4篇 |
2023年 | 7篇 |
2022年 | 8篇 |
2021年 | 9篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 13篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 20篇 |
2013年 | 9篇 |
2012年 | 9篇 |
2011年 | 6篇 |
2010年 | 9篇 |
2009年 | 9篇 |
2008年 | 9篇 |
2007年 | 8篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2003年 | 1篇 |
2002年 | 1篇 |
1994年 | 2篇 |
1991年 | 2篇 |
排序方式: 共有179条查询结果,搜索用时 15 毫秒
71.
72.
汶川8.0级地震后岷山山脉大熊猫栖息地自然遗产保护战略 总被引:1,自引:0,他引:1
岷山山脉是大熊猫的主要分布区,是我国保护大熊猫栖息地的关键区域之一。由于岷山山脉大熊猫栖息地处在南北地震带上,岷山山脉是大地震多发区与大熊猫栖息地重叠带。"5·12"汶川地震的高烈度区覆盖了岷山山脉北段大熊猫主栖息地的东部与南部,地震地面破裂带与极震区纵贯南段栖息地,导致北段主栖息地局部的严重地面破坏和南段栖息地大范围的严重地面破坏。通过调查汶川地震对栖息地的破坏情况,总结历史上地震对大熊猫栖息地的影响,分析汶川8.0级地震对岷山山脉大熊猫栖息地的影响程度,进而强调岷山山脉大熊猫栖息地自然遗产的重要性,提出岷山山脉大熊猫栖息地自然遗产保护战略。建议在岷山山脉北段建立涪江源国家级风景名胜区,编制岷山山脉大熊猫栖息地世界自然遗产扩展提名文本与保护规划。建议在岷山山脉南段建立龙门山地震遗址国家级风景名胜区,实施龙门山脉大熊猫栖息地与地震断层遗址保护计划。 相似文献
73.
为了克服已有物理栖息地模型仅能在具有较完善监测资料河流使用的局限性,介绍了一种应用模糊逻辑的物理栖息地模拟方法。该方法以河道平面二维流场模拟结果为基础,将鱼类学和生态学专家的知识经验融入物理栖息地模型中,运用模糊逻辑推理计算栖息地各单元适宜度,最后根据加权可用面积、高适宜度面积比例与流量的关系曲线确定生态需水量。运用该方法对葛洲坝坝下中华鲟产卵栖息地进行模拟。研究结果表明,中华鲟产卵期适宜生态需水量为10 000~17 000 m3/s。分析认为该方法对监测资料依赖程度低,使用专家知识经验能够弥补数据不足造成的不利影响,具有一定的可行性及实用性。该研究有助于监测资料不足的河流开展生态保护及河流管理工作,并且能够为模糊数学理论在水生态学中的应用提供参考。 相似文献
74.
The process of habitat degradation varies in habitat type and driving force which shows certain spatial and temporal heterogeneity on regional scales. In the present study, a new diagnostic model for enclosed bay habitat degradation was established, with which the spatial and temporal variation patterns of habitat degradation during 1991–2012 in Sansha Bay, Fujian, China was investigated. The results show that anthropogenic disturbance is the major controlling factor for the habitat degradation in large temporal heterogeneity in the bay. On the other hand, the habitat degradation experienced signifi cant spatial variations among six sub-bays. Under the joint action of temporal and spatial heterogeneity, the degradation trend in growing scale shows a more signifi cant correlation with the distribution of local leading industries along shorelines. Therefore, we quantifi ed the main characters of habitat degradation in Sansha Bay, and have understood the relationship between the status of habitats spatio-temporal variation value and the main controlling factor leading to the changes. However, a defi ciency of this research is the lack of or inaccessible to the detailed data, which shall be better solved in the future study for accessing more data from more sources. 相似文献
75.
XU Weihua Andrés VIA QI Zengxiang OUYANG Zhiyun LIU Jianguo LIU Wei WAN Hui 《中国地理科学(英文版)》2014,24(1):60-70
Many nature reserves are established to protect the habitat needs of particular endangered species of interest but their effec-tiveness for protecting other species is questionable.In this study,this effectiveness was evaluated in a nature reserve network located in the Qinling Mountains,Shaanxi Province,China.The network of reserves was established mainly for the conservation of the giant panda,a species considered as a surrogate for the conservation of many other endangered species in the region.The habitat suitability of nine protected species,including the giant panda,was modeled by using Maximum Entropy(MAXENT) and their spatial congruence was analyzed.Habitat suitability of these species was also overlapped with nature reserve boundaries and their management zones(i.e.,core,buffer and experimental zones).Results show that in general the habitat of the giant panda constitutes a reasonable surrogate of the habitat of other protected species,and giant panda reserves protect a relatively high proportion of the habitat of other protected species.Therefore,giant panda habitat conservation also allows the conservation of the habitat of other protected species in the region.However,a large area of suitable habitat was excluded from the nature reserve network.In addition,four species exhibited a low proportion of highly suitable habitat inside the core zones of nature reserves.It suggests that a high proportion of suitable habitat of protected species not targeted for conservation is located in the experimental and buffer zones,thus,is being affected by human activities.To increase their conservation effectiveness,nature reserves and their management zones need to be re-examined in order to include suitable habitat of more endangered species.The procedures described in this study can be easily implemented for the conservation of many endangered species not only in China but in many other parts of the world. 相似文献
76.
Specimens of a new species of Cerithiidae, Cerithium mangrovum n. sp., were collected during two surveys along the coasts of Hainan and Guangdong Province, China. Usually associated with potamidid snails, this species often occurs in large populations between the mid-high tidal zones in a range of habitats, including mangroves, grass beds, silt, mud, and coral reefs. C. mangrovum n. sp. has a slender and tapering shell and the straight-sided whorl bears three aligned beaded spiral cords. The thick outer lip has a wide posterior sinus. It morphologically resembles C. coralium Kiener, 1841. The shell of C. coralium is usually larger and wider and the spiral cords are not as beaded as in C, mangrovum n. sp. Its radula has a rachidian tooth with a shallow, wide, median basal projection while the rachidian tooth of C. mangrovum n. sp. has a moderately long, median basal projection. 相似文献
77.
78.
79.
40年前,《保护世界文化和自然遗产公约》在联合国教科文组织大会上通过。自此,大自然的鬼斧神工与人类祖先的倾心之作,以一种升华的方式真正进入人们视野,在"世界遗产"的名头与轨迹中,完成着各自不同的命运流转。自1972年《公约》施行之始, 相似文献
80.