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21.
作为一种土地利用活动,传统农林复合系统已经经历了成百上千年的历史,并且依然发挥着重要的作用在世界上,特别是热带和亚热带地区。在全球变化和粮食安全等危机的时代背景下,传统农林复合系统受到越来越多政府和非政府组织的重视,因为传统农林复合系统具有重要的经济、生态和社会文化效益。这与全球重要农业文化遗产要求的特征也相一致,目前为止,已经有5个国家4个典型的传统农林复合系统被列为全球重要农业文化遗产。这些传统农林复合系统具有丰富的农业生物多样性,多重的生态系统服务功能,重要的社会文化价值,无论在区域还是全球水平上。目前传统农林复合系统面临一些威胁和挑战,如人口迁移、市场冲击、气候变化等,但是只要政府和非政府组织、社区、农民之间采取多种方式紧密合作,在未来的全球土地利用活动中,传统农林复合系统必将得到有效保护和推广。  相似文献   
22.
INTRODUCTIONFresh water lakes are one of the planet’s mosti mportant freshwater resources.They support life invarious forms,develop tourism and provide uniquerecreational opportunities.It is also a good source ofthe provision of drinking-water for local communi-ties.Studies on trace elements in rivers,lakes,andsedi ments(Zhou et al.,2004;Gray et al.,2000;Grosheva et al.,2000;Klavins et al.,2000;Aucoinet al.,1999;Bortoli et al.,1998;Elbaz-Poulichet etal.,1996;Johansson et al.,1995;F r…  相似文献   
23.
根据台州市地理市情普查生产实践,基于普查成果内容,设计满足区域经济社会发展需求的统计分析评价主题及指标体系;以城市救灾避灾场所资源配置为案例,结合相关数据,利用叠加分析、可达性分析等模型深度挖掘国情信息,统计分析救灾避灾场所的步行可达性与服务范围,对社会民生工程救灾避灾场所的资源配置提出优化的建议。  相似文献   
24.
白洋淀浮游植物群落及其与环境因子的典范对应分析   总被引:7,自引:4,他引:7  
沈会涛  刘存歧 《湖泊科学》2008,20(6):773-779
在对湖泊生态系统健康评价研究的基础上,提出用营养状态-综合指数法(TSI-CI)对西湖进行生态系统健康评价.首先选用Chl.a、SD、TP和TN四个指标用相关加权指数法进行营养状态评价,再选择物化和生物指标无量纲化处理后计算综合指数进行综合评价.结果表明:西湖生态系统健康状况与营养状态水平的变化趋势是一致的,1—3月健康状况相对较好,7-9月相对较差.该结果客观反映了西湖的实际情况,为西湖水质管理提供科学依据。  相似文献   
25.
    
Finding the right balance between timber production and the management of forest-dependent wildlife species, present a difficult challenge for forest resource managers and policy makers in Okinawa, Japan. A possible explanation of this can be found in the unique nature of the forest management area which is populated with various kinds of rare and endangered species. This issue has been brought to light as a result of the nomination of northern Okinawa Island in 2018 as a candidate for World Natural Heritage site. The nomination has raised public awareness to the possibility of conflicting management objectives between timber extraction and the conservation of habitat for forest-dependent wildlife species. Managing exclusively for one objective over the other may fail to meet the demand for both forest products and wildlife habitat, ultimately jeopardizing the stability of human and wildlife communities. It is therefore important to achieve a better balance between the objective of timber production and conservation of wildlife habitat. Despite the significance of this subject area, current ongoing discussions on how to effectively manage for forest resources, often lack scientific basis to make sound judgement or evaluate tradeoffs between conflicting objectives. Quantifying the effect of these forest management activities on wildlife habitat provides useful and important information needed to make forest management and policy decisions. In this study we develop a spatial timber harvest scheduling model that incorporates habitat suitability index (HSI) models for the Okinawa Rail (Gallirallus okinawae), an endangered avian species found on Okinawa, Japan. To illustrate how the proposed coupling model assembles spatial information, which ultimately aids the study of forest management effects on wildlife habitat, we apply these models to a forest area in Okinawa and conduct a simple simulation analysis.  相似文献   
26.
为了可以精准且高效地实现海洋微生物种群多样性信息分类, 本文提出一种基于支持向量机(Support Vector Machine, SVM) 算法的海洋微生物种群多样性信息自适应分类方法。通过无线传感器网络展开海洋微生物种群信息采集点的部署, 建立海洋微生物种群信息采集信道模型, 在带宽受距离约束条件下设计载频频率编码, 利用波特间隔均衡控制方法达到海洋微生物种群信息采集优化的目的。在核空间中, 对采集的海洋微生物种群信息展开谱聚类, 确定具有代表性的信息点, 同时引入SVM 对全部样本进行训练, 最终实现海洋微生物种群多样性信息自适应分类。实验结果表明: 所提方法的平均精度均值(mean Average Precision, mAP) 稳定在95%以上, 可以有效提升海洋微生物种群多样性信息自适应分类的准确性和分类效率。  相似文献   
27.
三峡库区特大滑坡灾害防治工程评价方法初探   总被引:3,自引:1,他引:3  
张勇  石胜伟  宋军 《地质通报》2013,32(12):2015-2020
以三峡库区特大滑坡灾害为研究对象,汇总、分析了库区72处特大滑坡灾害的防治工程措施,总结了三峡库区特大滑坡灾害防治技术的特点。通过对三峡库区特大滑坡灾害防治工程的基本类型与防灾特点的分析,建立了特大滑坡灾害防治措施的评价指标体系,并依照评价指标和标准对滑坡灾害防治工程效果进行分级。  相似文献   
28.
    
As one of the key parameters for characterizing crop canopy structure, Leaf Area Index (LAI) has great significance in monitoring the crop growth and estimating the yield. However, due to the nonlinearity and spatial heterogeneity of LAI inversion model, there exists scale error in LAI inversion result, which limits the application of LAI product from different remote sensing data. Therefore, it is necessary to conduct studies on scale effect. This study was based on the Heihe Oasis, Zhangye city, Gansu province, China and the following works were carried out: Airborne hyperspectral CASI (Compact Airborne Spectrographic Imager) image and LAI statistic models were adopted in muti-scale LAI inversion. The overall difference of muti-scale LAI inversion was analyzed in an all-round way. This was based on two aspects,   相似文献   
29.
    
The application of remote sensing in understanding tree species structural diversity and land use patterns relationship is imperative for reforestation and biodiversity conservation efforts. This study assesses land use patterns and tree species structural diversity in previously reforested hilly sandstone regions of northern Togo. The physical height, and diameter at breast height (DBH) more than 5 cm of all tree species in each given plot were measured in summer 2017. A total of 75 plots of 900 m2 installed along the toposequence were recorded. In addition, a semi-supervised classification of Landsat 8 images in January of 2018, was also used to classify the land use patterns. 36 tree species and 19 families were recorded for the entire study area. Meanwhile, 19 tree species and 15 families were recorded for the previously afforested zones. The most abundant species included the Sterculiaceae, Zygophyllaceae, Meliaceae, and Mimosaceae. The trees stand structure represented 8.61 ± 0.57 m, 11.28 ± 1.76 cm, and 0.018 ± 0.009 m2 per hectare for height, diameter and basal area respectively. Major land use patterns were tree and shrub savannahs, parklands and croplands which represented over 60% of the landscape. It is necessary to examine the regeneration and vegetative multiplication potentials of the most frequent and abundant tree species for any eventual future afforestation programs in these hilly sandstone regions of northern Togo.  相似文献   
30.
Ascertaining the relationship between \"source-sink\" landscape and non-point source(NPS) pollution is crucial for reducing NPS pollution, however, it is not easy to realize this target on cell unit scale. To reveal the relationships between \"sourcesink\" landscape and NPS pollution based on cell units of a small catchment in the Three Gorges Reservoir Region(TGRR), the runoff and nutrient yields were simulated first by rainfall events on a cell unit scale based on the Annualized AGricultural Non-Point Source Pollution Model(AnnAGNPS). Landscape structure and pattern were quantified with \"sourcesink\" landscape indicators based on cell units including landscape area indices and locationweighted landscape indices. The results showed that:the study case of small Wangjiagou catchment highlighted a good prediction capability of runoff and nutrient export by the AnnAGNPS model. Throughout the catchment, the spatial distribution trends of four location-weighted landscape indices were similar to the trends of simulated total nitrogen(TN) and total phosphorus(TP), which highlighted the importance of spatial arrangement of \"source\" and \"sink\" landscape types in a catchment when estimating pollutant loads. Results by Pearson correlation analysis indicated that the location-weighted landscape index provided a more comprehensive account of multiple factors, and can better reflect NPS-related nutrient loss than other landscape indices applied in single-factor analysis. This study provides new findings for applying the \"source-sink\" landscape indices based on cell units in small catchments to explain the effect of \"source-sink\" landscape on nutrient export based on cell unit, and helps improve the understanding of the correlation between \"source-sink\" landscape and NPS pollution.  相似文献   
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