全文获取类型
收费全文 | 6910篇 |
免费 | 1316篇 |
国内免费 | 1701篇 |
专业分类
测绘学 | 333篇 |
大气科学 | 1448篇 |
地球物理 | 1845篇 |
地质学 | 3376篇 |
海洋学 | 1013篇 |
天文学 | 219篇 |
综合类 | 865篇 |
自然地理 | 828篇 |
出版年
2024年 | 29篇 |
2023年 | 124篇 |
2022年 | 340篇 |
2021年 | 376篇 |
2020年 | 349篇 |
2019年 | 322篇 |
2018年 | 389篇 |
2017年 | 364篇 |
2016年 | 438篇 |
2015年 | 313篇 |
2014年 | 411篇 |
2013年 | 376篇 |
2012年 | 358篇 |
2011年 | 378篇 |
2010年 | 419篇 |
2009年 | 370篇 |
2008年 | 319篇 |
2007年 | 320篇 |
2006年 | 277篇 |
2005年 | 209篇 |
2004年 | 200篇 |
2003年 | 211篇 |
2002年 | 203篇 |
2001年 | 185篇 |
2000年 | 205篇 |
1999年 | 325篇 |
1998年 | 300篇 |
1997年 | 284篇 |
1996年 | 235篇 |
1995年 | 245篇 |
1994年 | 214篇 |
1993年 | 175篇 |
1992年 | 153篇 |
1991年 | 92篇 |
1990年 | 91篇 |
1989年 | 75篇 |
1988年 | 50篇 |
1987年 | 40篇 |
1986年 | 22篇 |
1985年 | 25篇 |
1984年 | 26篇 |
1983年 | 15篇 |
1982年 | 18篇 |
1981年 | 17篇 |
1980年 | 12篇 |
1979年 | 12篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1958年 | 4篇 |
排序方式: 共有9927条查询结果,搜索用时 15 毫秒
301.
Di-di Sun Yue-jiao Li Wen-qiang Zhao Zi-liang Zhang Dan-dan Li Chun-zhang Zhao Qing Liu 《山地科学学报》2016,13(8):1442-1452
Soil microbial communities are primarily regulated by environmental temperature. Our study investigated the effects of global warming on soil microbial community composition as measured via phospholipid fatty acid (PLFA) analysis and soil chemical characteristics in relation to soil depth in a dragon spruce plantation and a spruce-fir-dominated natural forestin the Eastern Tibetan Plateau. Open-top chambers were utilized to increase the soil and air temperature. Soil samples were collected from the 0-10 cm, 10-20 cm, and 20-30 cm layers after a 4-year warming. Our results showed that the soil microbial community and the contents of TC (Total carbon), TN (Total nitrogen), NO 3 - , and NH 4 + responded differently to warming in the two contrasting forests, especially at the 0-10 cm soil depth. Warming increased soil microbial biomass at the 0-20 cm depth of soil in natural forest but reduced it at the 0-10 cm depth ofsoil in the plantation. In contrast, the TC and TN contents were reduced in most soil layers of a natural forest but increased in all of the soil layers of the plantation under warming conditions. This result suggested that the effects of warming on soil microbial community and soil C and N pools would differ according to soil depth and forest types; thus, the two contrasting forests would under go differing changes following the future climate warming in this region. 相似文献
302.
303.
Wei-yue Li Chun Liu Yang Hong Xin-hua Zhang Zhan-ming Wan Manabendra Saharia Wei-wei Sun Dong-jing Yao Wen Chen Sheng Chen Xiu-qin Yang Yue Yue 《山地科学学报》2016,13(7):1275-1285
Landslide inventory plays an important role in recording landslide events and showing their temporal-spatial distribution. This paper describes the development, visualization, and analysis of a China's Landslide Inventory Database (CsLID) by utilizing Google’s public cloud computing platform. Firstly, CsLID (Landslide Inventory Database) compiles a total of 1221 historical landslide events spanning the years 1949-2011 from relevant data sources. Secondly, the CsLID is further broken down into six zones for characterizing landslide cause-effect, spatiotemporal distribution, fatalities, and socioeconomic impacts based on the geological environment and terrain. The results show that among all the six zones, zone V, located in Qinba and Southwest Mountainous Area is the most active landslide hotspot with the highest landslide hazard in China. Additionally, the Google public cloud computing platform enables the CsLID to be easily accessible, visually interactive, and with the capability of allowing new data input to dynamically augment the database. This work developed a cyber-landslide inventory and used it to analyze the landslide temporal-spatial distribution in China. 相似文献
304.
305.
Lei Xing Huaishan Liu Xilai Zheng Xueqin Liu Jin Zhang Linfei Wang Zhihui Zou Yiming Xu 《中国海洋大学学报(英文版)》2016,15(5):815-824
Air guns are important sources for marine seismic exploration. Far-field wavelet of air gun arrays, as a necessary parameter for pre-stack processing and source models, plays an important role during marine seismic data processing and interpretation. When an air gun fires, it generates a series of air bubbles. Similar to onshore seismic exploration, the water forms a plastic fluid near the bubble; the farther the air gun is located from the measurement, the more steady and more accurately represented the wavelet will be. In practice, hydrophones should be placed more than 100 m from the air gun; however, traditional seismic cables cannot meet this requirement. On the other hand, vertical cables provide a viable solution to this problem. This study uses a vertical cable to receive wavelets from 38 air guns and data are collected offshore Southeast Qiong, where the water depth is over 1000 m. In this study, the wavelets measured using this technique coincide very well with the simulated wavelets and can therefore represent the real shape of the wavelets. This experiment fills a technology gap in China. 相似文献
306.
307.
308.
309.
310.