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22.
In mountainous Mediterranean regions, land abandonment processes in past decades are hypothesized to trigger secondary vegetal
succession and homogenization, which in recent years has increased the size of burned areas. We conducted an analysis of temporal
changes in landscape vegetal spatial pattern over a 15-year period (1984–1998) in a rural area of 672.3 km2 in Eastern Spain to investigate the relationship between local landscape heterogeneity and wildfire occurrence. Heterogeneity
was analyzed from textural metrics derived from non-classified remote sensing data at several periods, and was related to
wildfire history in the study area. Several neural network models found significant relationships between local spatial pattern
and future fire occurrence. In this study, sensitivity analysis of the texture variables suggested that fire occurrence, estimated
as probability of burning in the near future, increased where local homogeneity was higher. 相似文献
23.
Regional land-cover change affects biodiversity, hydrology, and biogeochemical cycles at local, watershed, and landscape scales.
Developing countries are experiencing rapid land cover change, but assessment is often restricted by limited financial resources,
accessibility, and historical data. The assessment of regional land cover patterns is often the first step in developing conservation
and management plans. This study used remotely sensed land cover and topographic data (Landsat and Shuttle Radar Topography
Mission), supervised classification techniques, and spectral mixture analysis to characterize current landscape patterns and
quantify land cover change from 1985 to 2003 in the Altiplano (2535–4671 m) and Intermediate Valley (Mountain) (1491–4623 m)
physiographic zones in the Southeastern Bolivian Andes. Current land cover was mapped into six classes with an overall accuracy
of 88% using traditional classification techniques and limited field data. The land cover change analysis showed that extensive
deforestation, desertification, and agricultural expansion at a regional scale occurred in the last 20 years (17.3% of the
Mountain Zone and 7.2% of the Altiplano). Spectral mixture analysis (SMA) indicated that communal rangeland degradation has
also occurred, with increases in soil and non-photosynthetic vegetation fractions in most cover classes. SMA also identified
local areas with intensive management activities that are changing differently from the overall region (e.g., localized areas
of increased green vegetation). This indicates that actions of local communities, governments, and environmental managers
can moderate the potentially severe future changes implied by the results of this study. 相似文献
24.
利用遥感技术监测锡林郭勒天然草原利用强度方法初探 总被引:1,自引:0,他引:1
利用多时相的遥感数据,对2005年锡林郭勒天然草原生长期放牧利用强度进行了信息提取、监测和制图。结果表明:在牧草生长季节,天然草原各旬度的利用强度与植被指数旬度变动系数成反比,并与降雨和植被长势时空分布格局相一致;放牧初期旬度变动系数下降4%左右,利用强度较轻,处于轻度过牧状态;6月中旬以后,旬度变动系数下降12%~20%之间,利用强度加重,处于中度超载过牧状态;8月下旬后植物生长停止,旬度变动系数下降27%左右,利用强度最重,处于重度超载过牧状态。遥感监测结果经过地面同步采集数据验证,监测精度达到79.6%。 相似文献
25.
S. Flasse C. Walker H. Biggs P. Stephenson P. Hutchinson 《Preventive veterinary medicine》1998,33(1-4):31-38
The Directorate of Veterinary Services of the Ministry of Agriculture, Water and Rural Development of Namibia issues warnings to farmers in the south of the country about the likelihood of infestation of small-stock by the nasal bot fly, Oestrus ovis. Farmers can then treat their stock at the most appropriate time. The O. ovis puparia develop at shallow depths in the soil and the timing of emergence is directly dependent on climatic conditions, specifically the number of degree-days above a particular threshold soil temperature. Based on temperature measurements from only a few stations scattered throughout the country, the veterinary department warnings lack precision in space and time. This paper presents an attempt to support the programme of warnings with accumulated temperature information from Meteosat satellite images, in order to strengthen predictions of the time of emergence in specific places, and to improve the precision and reliability of warnings given to farmers. 相似文献
26.
The objective of this study is to present a new application of optical and radar remote sensing with high spatial (∼10 m) and temporal (a few days) resolutions for the detection of tillage and irrigation operations. The analysis was performed for irrigated wheat crops in the semi-arid Tensift/Marrakech plain (Central Morocco) using three FORMOSAT-2 images and two ASAR images acquired within one week at the beginning of the 2005/2006 agricultural season.The approach we developed uses simple mapping algorithms (band thresholding and decision tree) for the characterisation of soil surface states. The first images acquired by FORMOSAT and ASAR were processed to classify fields into three main categories: ploughed (in depth), prepared to be sown (harrowed), and not ploughed-not harrowed. This information was combined with a change detection analysis based on multitemporal images to identify harrowing and irrigation operations which occurred between two satellite observations.The performance of the algorithm was evaluated using data related to land use and agricultural practices collected on 124 fields. The analysis shows that drastic changes of surface states caused by ploughing or irrigation are detected without ambiguity (consistency index of 96%). This study provided evidence that optical and radar data contain complementary information for the detection of agricultural operations at the beginning of agricultural season. This information could be useful in regional decision support systems to refine crop calendars and to improve prediction of crop water needs over large areas. 相似文献
27.
采用嵌入式网络模块NetBox2,利用其网络接口和TCP/IP协议库进行二次开发,实现了一个远程农业信息采集客户端。支持人工观测数据和农业数据检测仪器两种方式下的农业数据采集、远程传输和存储。 相似文献
28.
QuickBird影像目视判读在土地利用类型调查中的应用研究 总被引:6,自引:0,他引:6
利用Q u ickB ird影像数据进行土地利用类型调查过程中采用人工目视判读或人机交互式判读方法能获取相对准确的土地利用类型信息。目视判读的难点是对易混淆地类和森林类型的判读,包括草地与农田、灌木林与果园地、经济林与用材林、陡坡地与常年旱地等。通过适当的前期图像处理,以建立解译标志为基础,采取综合的判读方法可将上述类型大部分判读出来。 相似文献
29.
通过对长江中上游天然林资源保护工程川东北地区的遥感监测,全面分析了工程实施以来取得的成绩和存在的问题,提出了相应的对策措施。 相似文献
30.
利用美国Landsat-7的ETM+数据作为主要数据源,采用ERMAPPER7.0专用图像处理软件制作了湖南省四水流域和洞庭湖水域解译图,获取了湖南省水资源的空间分布信息。结果表明:湘、资、沅、澧四水和洞庭湖水域面积总和为6224.72km^2,其中洞庭湖水域面积为2710.13km^2,湘江省内长度为722.07km,资水省内长度为687.31km,沅水省内长度为597.35km,澧水省内长度为423.57km,说明利用遥感技术调查湖南省水资源具有快速、准确和高效的特点。 相似文献