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161.
青藏高原植被覆盖对水热条件年内变化的响应及其空间特征 总被引:7,自引:0,他引:7
利用1982-2000年NOAA/AVHRR卫星的NDVI数据(时间分辨率旬,空间分辨率8 km×8 km),结合同时期的气温和降水资料,基于时滞互相关方法和GIS工具,分析了青藏高原植被覆盖对水、热条件年内变化的时滞响应及其空间特征。结果如下:①除高寒荒漠、森林外,青藏高原植被NDVI与同期旬均温和旬降水相关性均呈高度正相关。其中,中等覆盖度的植被受水、热影响表现更为强烈。②青藏高原植被NDVI对气温和降水有滞后效应,且滞后水平存在空间差异,高原北部(柴达木盆地、昆仑山北冀)和高原南部植被对降水、和温度的响应比较迟缓,而高原中、东部地区植被对温度和降水的响应比较敏感。③不同植被类型对水热条件的响应程度也存在差异,由高到低依次是草甸、草原、灌丛、高寒垫状植被、荒漠,最后是森林。 相似文献
162.
The dynamic response of lakes in the Tuohepingco Basin of the Tibetan Plateau to climate change 总被引:1,自引:0,他引:1
The Tibetan Plateau (TP) is particularly sensitive to the influences of climate change. As indicators of climate change, lakes on the TP play a key role in the Earth’s climatic system. Lake Yazi (LY), Lake Tuohepingco (LT) and Lake Changtiao (LC) in the Tuohepingco Basin are three inland lakes on the plateau. The extents of LY, LT and LC were obtained using object-based image analysis for remote sensing and 22 images from Landsat satellites (from September to December between 1972 and 2015). Inter-annual changes in the extent of LY, LT and LC were then analyzed. The results show that the total area of the three lakes underwent a change from shrinkage to expansion between 1972 and 2015. In general, there was a trend toward shrinkage during 1972–1999, distinct expansion during 2000–2007 and slight expansion during 2008–2015. Moreover, we found that 14 other lakes have also expanded dramatically since 2000. Lakes at 30°N and 35°N (LY, LT and LC are also located in this region) exhibited the same dramatic period of expansion between 2000 and 2005. In other words, 2000 appears to be a critical transition point for changes in lake size on the TP. Lakes at the same latitudes in the Tibetan Plateau interior may have a similar period of dramatic expansion after 2000. The warming-triggered deglaciation or permafrost degradation, increased precipitation and decreased evapotranspiration may be the influencing factors of lake expansion in the Tuohepingco Basin. Temperature showed relatively higher correlation with lake extent, while precipitation and evaporation were slightly correlated with lake area. Given the importance of wetlands to human society, these are no trivial issues, and we now need accelerated research based on long-term and continuous remote sensing. 相似文献
163.
Xainza County on the Qiangtang Plateau (QP) spans a transitionally climatic and eco-environmental zone and is therefore a very sensitive region. Glaciers in this area are one of the most important kinds of land cover as well as key water resources, yet our understanding of their current status and spatio-temporal change remains limited. Using Landsat images, this study investigated the current distribution of glaciers (2015) in the Xainza Xiegang Mountains as well as the spatio-temporal changes that took place over six time periods between 1976 and 2015. Results show that, in 2015, 131 glaciers covered a total area of 74.59 ± 5.25 km2, mainly located between 5,600 and 6,000 m above sea level (a.s.l). Between 1976 and 2015, the total number of glaciers increased by 12, while their areas decreased by 24.98% (24.83 km2). Glacial retreat has induced a loss of water resources of 11.77 × 108 m3 over the last 39 years, while spatial heterogeneities in glacial changes across various sub-basins, aspects, and altitudinal zones are also clearly observed. Climate warming is the key factor driving this continuous glacial retreat; the high-quality dataset presented in this paper for the Xainza Xiegang study area is crucial for the ongoing assessment of climatic and eco-environmental changes. 相似文献
164.
165.
YAN Jianzhong ZHANG Yili LIU Linshan BAI Wanqi ZHU Huiyi SHI Yulin ZHENG Du 《地理学报》2006,16(3):293-305
1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China; 2. College of Resources and Environment, Southwest University, Chongqing 400716, China; 3. Institute of Tibetan Plateau Research, CAS, Beijing 100085, China) 相似文献
166.
Research on forest phenology is an important parameter related to climate and environmental changes. An optical camera was used as a near-earth remote sensing satellite device to obtain forest images, and the data of Green excess index (GEI) in the images were calculated, which was fitted with the seasonal variation curve of GEI data by double Logistic method and normalization method. LSTM and GRU deep learning models were introduced to train and test the GEI data. Moreover, the rationality and performance evaluation of the deep learning model were verified, and finally the model predicted the trend of GEI data in the next 60 days. Results showed: In the aspects of forest phenology training and prediction, GRU and LSTM models were verified by histograms and autocorrelation graphs, indicating that the distribution of predicted data was consistent with the trend of real data, LSTM and GRU model data were feasible and the model was stable. The differences of MSE, RMSE, MAE and MAPE between LSTM model and GRU model were 0.0014, 0.013, 0.008 and 5.26%, respectively. GRU had higher performance than LSTM. The prediction of LSTM and GRU models about GEI data for the next 60 days both showed a trend chart consistent with the change trend of GEI data in the first half of the year. GRU and LSTM were used to predict GEI data by deep learning model, and the response of LSTM and GRU deep learning models in forest phenology prediction was realized, and the performance of GRU was better than that of LSTM model. It could further reveal the growth and climate change of forest phenology in the future, and provide a theoretical basis for the application of forest phenology prediction. 相似文献
167.
Journal of Geographical Sciences - Traditional trade routes that penetrate the natural barrier of the Himalayas are critical for connecting major Chinese and South Asian markets. Research on these... 相似文献
168.
中全新世气候突变对青海东北部史前文化的影响 总被引:8,自引:2,他引:8
青海东北部自然环境对全球变化响应敏感,且本区史前文化发达、序列完整、遗迹丰富。因此本区是我国研究气候变化对史前文化影响的典型区域。利用气候和考古研究结果,采用GIS和数学分析方法,发现:4 kaBP本区气候向干冷化突变,齐家文化在3.9 kaBP突然衰弱,在干冷形势基本稳定的3.6 kaBP,出现辛店文化和卡约文化,遗址数猛增;齐家文化是农耕文化,辛店文化继承了齐家文化的生产活动,其地域范围缩小,向低海拔和向东部的低山丘陵、河谷、沟谷地带退缩;而卡约文化在适应气候突变后,改变了原有的生产方式,产生了一种新的经济方式--畜牧业,并向西和更高海拔的中山地、高山地等扩展,地域范围达到史前文化最大。因此气候突变,史前居民采取了不同的应对策略,进而形成不同的文化,气候突变是本区史前文化由单一向多元分异的重要驱动力,也是本区大型聚落难以维系,文明进程受挫的重要原因。 相似文献
169.
Glacial change in the vicinity of Mt. Qomolangma (Everest), central high Himalayas since 1976 总被引:4,自引:0,他引:4
Glaciers are one of the most important land covers in alpine regions and especially sensitive to global climate change. Remote
sensing has proved to be the best method of investigating the extent of glacial variations in remote mountainous areas. Using
Landsat thematic mapping (TM) and multi-spectral-scanner (MSS) images from Mt. Qomolangma (Everest) National Nature Preserve
(QNNP), central high Himalayas for 1976, 1988 and 2006, we derived glacial extent for these three periods. A combination of
object-oriented image interpretation methods, expert knowledge rules and field surveys were employed. Results showed that
(1) the glacial area in 2006 was 2710.17 ± 0.011 km2 (about 7.41% of the whole study area), and located mainly to the south and between 4700 m to 6800 m above sea level; (2)
from 1976 to 2006, glaciers reduced by 501.91 ± 0.035 km2 and glacial lakes expanded by 36.88 ± 0.035 km2; the rate of glacier retreat was higher in sub-basins on the southern slopes (16.79%) of the Himalayas than on the northern
slopes (14.40%); most glaciers retreated, and mainly occurred at an elevation of 4700–6400 m, and the estimated upper limit
of the retreat zone is between 6600 m and 6700 m; (3) increase in temperature and decrease in precipitation over the study
period are the key factors driving retreat. 相似文献
170.
青藏高原东部样带农牧民生计的多样化 总被引:20,自引:2,他引:20
随着草地退化和药材资源减少,青藏高原东部农牧民的生计受到了严重影响.农牧民如何利用生计资产实现生计多样化是该区域可持续发展面临的关键问题.实地调查采用PRA法,结合调查结果调整了生计资产评估指标,从样带尺度定量分析了高原东部高山峡谷区、山原区和高原区农牧民的生计资产现状、生计多样化特点和今后的生计策略.结果表明:①生计多样化是农牧民普遍采用的生计策略.高山峡谷区农牧民生计多样化水平较高,从事二三产业较多,普遍寻求发展型生计.而随着海拔升高,农牧民的生计多样化水平降低,从事的生计活动类型减少,发展型生计的比例也降低;②海拔较低的高山峡谷区和山原区,生计资产总值高,而海拔越高的高原区,生计资产总值较低,主要反映在人力资产和自然资产上;③居民所拥有的生计资产与生计多样化水平高度正相关;④农牧民近期仍基于生计资产改善生计策略;⑤高山峡谷区和山原区农牧民寻求发展型生计为高原区牧民提供了很好的借鉴.建议政府围绕生计多样化的制约因素进行投入,以提高牧民的能力,协助高原区牧民建立发展型生计. 相似文献