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本文简述了文献传递服务发展的基本过程,概括了联合参考咨询网服务模式与内容,对现阶段UCDRS存在的问题进行分析与探讨,提出了解决问题的方法及优化措施,积极整合各类图书馆信息资源和服务力量,促进公益性联合参考咨询系统的发展。 相似文献
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森林消防装备是森林消防工作的基础,是森林防火灭火能力的体现。分析了我国消防装备的现状和存在的问题,探讨了提高我国森林消防装备使用效益的措施。 相似文献
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电子阅览室是图书馆实现数字化发展的重要成果。文章在阐释电子阅览室功能的基础上,以山西农业大学为例,从电子阅览室服务现状出发,分析了山西农业大学电子阅览室服务中存在的问题,并提出了加强设备管护、提升工作人员综合素质、加大宣传力度、加强规章制度建设等方面的对策建议,以期提升电子阅览室服务质量。 相似文献
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Urban forests (UF) provide a range of important ecosystem services (ES) for human well-being. Relevant ES delivered by UF include urban temperature regulation, runoff mitigation, noise reduction, recreation, and air purification. In this study the potential of air pollution removal by UF in the city of Florence (Italy) was investigated. Two main air pollutants were considered – particulate matter (PM10) and tropospheric ozone (O3) – with the aim of providing a methodological framework for mapping air pollutant removal by UF and assessing the percent removal of air pollutant.The distribution of UF was mapped by high spatial resolution remote sensing data and classified into seven forest categories. The Leaf Area Index (LAI) was estimated spatially using a regression model between in-field LAI survey and Airborne Laser Scanning data and it was found to be in good linear agreement with estimates from ground-based measurements (R2 = 0.88 and RMSE% = 11%). We applied pollution deposition equations by using pollution concentrations measured at urban monitoring stations and then estimated the pollutant removal potential of the UF: annual O3 and PM10 removal accounted for 77.9 t and 171.3 t, respectively. O3 and PM10 removal rates by evergreen broadleaves (16.1 and 27.3 g/m2), conifers (10.9 and 28.5 g/m2), and mixed evergreen species (15.8 and 31.7 g/m2) were higher than by deciduous broadleaf stands (4.1 and 10 g/m2). However, deciduous forests exhibited the largest total removal due to the high percentage of tree cover within the city. The present study confirms that UF play an important role in air purification in Mediterranean cities as they can remove monthly up to 5% of O3 and 13% of PM10. 相似文献
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概述了达川区蔬菜生产全程社会化服务的现状、取得成效及主要措施,分析了存在的问题,并提出了增加补助环节、提高补助标准、培育服务主体、创新服务机制的发展对策。 相似文献
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Shifts in microbial diversity through land use intensity as drivers of carbon mineralization in soil
Land use practices alter the biomass and structure of soil microbial communities. However, the impact of land management intensity on soil microbial diversity (i.e. richness and evenness) and consequences for functioning is still poorly understood. Here, we addressed this question by coupling molecular characterization of microbial diversity with measurements of carbon (C) mineralization in soils obtained from three locations across Europe, each representing a gradient of land management intensity under different soil and environmental conditions. Bacterial and fungal diversity were characterized by high throughput sequencing of ribosomal genes. Carbon cycling activities (i.e., mineralization of autochthonous soil organic matter, mineralization of allochthonous plant residues) were measured by quantifying 12C- and 13C-CO2 release after soils had been amended, or not, with 13C-labelled wheat residues. Variation partitioning analysis was used to rank biological and physicochemical soil parameters according to their relative contribution to these activities. Across all three locations, microbial diversity was greatest at intermediate levels of land use intensity, indicating that optimal management of soil microbial diversity might not be achieved under the least intensive agriculture. Microbial richness was the best predictor of the C-cycling activities, with bacterial and fungal richness explaining 32.2 and 17% of the intensity of autochthonous soil organic matter mineralization; and fungal richness explaining 77% of the intensity of wheat residues mineralization. Altogether, our results provide evidence that there is scope for improvement in soil management to enhance microbial biodiversity and optimize C transformations mediated by microbial communities in soil. 相似文献
68.
肖沛然 《湖南农业大学学报(自然科学版)》2015,(4):21-26
通过数学建模方法可知,由于出租车公司和政府部门追求垄断利润,出租车司机和消费者的福利减少,因此,对消费者和司机来说,出租车行业垄断确实是一种伤害.互联网专车服务以低廉的价格和优质的服务,是打破出租车行业垄断的有力工具.从模型分析揭示的结果可知:传统的出租车行业必须对司机、消费者、公司和政府间的利润分配制度进行深层次的改革.只有这样,才能建立一个和谐的出租车服务体系. 相似文献
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