全文获取类型
收费全文 | 1580篇 |
免费 | 106篇 |
国内免费 | 174篇 |
专业分类
林业 | 187篇 |
农学 | 205篇 |
基础科学 | 210篇 |
238篇 | |
综合类 | 529篇 |
农作物 | 179篇 |
水产渔业 | 94篇 |
畜牧兽医 | 119篇 |
园艺 | 51篇 |
植物保护 | 48篇 |
出版年
2024年 | 13篇 |
2023年 | 36篇 |
2022年 | 73篇 |
2021年 | 66篇 |
2020年 | 75篇 |
2019年 | 91篇 |
2018年 | 68篇 |
2017年 | 86篇 |
2016年 | 101篇 |
2015年 | 54篇 |
2014年 | 101篇 |
2013年 | 126篇 |
2012年 | 123篇 |
2011年 | 148篇 |
2010年 | 85篇 |
2009年 | 110篇 |
2008年 | 58篇 |
2007年 | 67篇 |
2006年 | 45篇 |
2005年 | 29篇 |
2004年 | 29篇 |
2003年 | 32篇 |
2002年 | 24篇 |
2001年 | 23篇 |
2000年 | 26篇 |
1999年 | 17篇 |
1998年 | 17篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 16篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 12篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有1860条查询结果,搜索用时 15 毫秒
101.
通过对我国海南、云南、广东三大植胶区橡胶产业发展情况的调研,简要阐述橡胶采胶及病虫害防控方面的现状。探讨分析橡胶采胶及病虫害方面所面临的采胶技术管理执行不够好,橡胶树割面干涸病防控技术仍未获得突破,橡胶树常规病虫危害日趋严重及新病虫害不断涌现,橡胶栽培技术经济合理性研究不够等问题。提出通过切实做好采胶技术管理,割面干涸病防控技术研发,高效安全的采胶技术及新型刺激剂复方的研发,橡胶树突发病虫害监测预报及应急防控技术,橡胶树根病综合防控及植保药物技术研发等建议,发展提升橡胶产业整体水平。 相似文献
102.
周俊 《信阳农业高等专科学校学报》2010,20(3):47-48
面对日益发展的金融证券及保险业我国银行监管仍显不足。应抓紧完善银行监管法律制度和非现场监管机制,建立监管信息平台,提高现场检查效率。 相似文献
103.
依据秋白菜受冻的日最低气温指标,利用本溪市1957~2008年逐日最低气温资料,应用模糊数学隶属度函数预测日最低≤-7℃的初日趋势,建立多元回归模型预测日最低气温≤-7℃初日,为指导秋白菜适时收获、合理安排上期提供科学的气象依据。 相似文献
104.
模型构造的方法是以Logistic方程描述生长量 ,假设采伐量为常量且等于生长量时 ,推导出折迭突变模型 .此模型有助于管理层制定管理决策 ,防止森林消亡 .该文又通过曲线采伐模型及Logistic生长模型推导出尖角突变模型 ,这个模型给出了采伐将导致突变发生的敏感区域 ,而且通过模型的滞后性使人们清楚地意识到森林一旦遭受破坏 ,再想恢复需入更大的力量 相似文献
105.
先进的牧草种子收获和加工工艺及装备应用前景探讨 总被引:5,自引:0,他引:5
论述了牧草种子收获和加工特点、先进的加工工艺及先进的装备。在分析国内现状的基础上,提出了我国牧草种子收获和加工未来重点开发和研究的对象。 相似文献
106.
Intercropped wheat (Triticum aestivum L.) and bean (Vicia faba L.) as a whole-crop forage: effect of harvest time on forage yield and quality 总被引:1,自引:0,他引:1
Abstract Sole crops and intercrops of wheat (Triticum aestivum L.) and bean (Vicia faba L.), at three harvest dates, representing successive growth stages, were evaluated for biomass production of whole‐crop forage and quality characteristics of crude protein (CP), neutral‐detergent fibre (NDF), acid‐detergent fibre (ADF), water‐soluble carbohydrate (WSC) concentrations and ash content. These tests were carried out for two field experiments, respectively, drilled during the spring of 1997 and autumn of 1997 on Imperial College Farm, Wye, UK. Results indicated that optimum forage yield and quality were obtained from the second to third harvest dates for the spring‐drilled experiment and the second harvest for the autumn‐drilled experiment. Wheat and bean intercrops were higher in total forage dry matter (DM) yield than either wheat or bean grown as sole crops. Field bean intercropped with wheat led to increased forage quality (CP and NDF concentrations) compared with sole wheat, and higher WSC concentrations compared with sole bean. Intercrops also enhanced weed suppression compared with sole bean. It is suggested that winter wheat–bean intercrops may have considerable potential as a moderate‐yielding, relatively high‐quality, low‐input and environmentally benign forage crop with considerable potential with regard to yield and quality and warrant further study. 相似文献
107.
阳东辉 《湖南农业大学学报(自然科学版)》2001,(3)
鉴于我国公司法对公司相互持股问题的规制处于空白之现状,文章借鉴国际上最新立法成果,分析了公司相互持股所引发的诸多问题,并提出规制公司相互持股问题的建议与构想。 相似文献
108.
The need to increase forage production for the growing livestock population in the Mediterranean region necessitates the evaluation of various promising forage species with respect to maximum herbage yield, optimum time for harvest and seed yield. Seven forage legumes, woolly pod vetch ( Vicia villosa subsp. dasycarpa accession 683), narbon vetch (V. narbonensis accession 67), common vetch ( V. sativa selections 2541, 2037, 2020), common chickling ( Lathyrus sativus selection 439) and ochrus chickling ( L. ochrus selection 104) were compared over two years with contrasting rainfall. In both years the entries were sown in November and their primary growths sampled periodically during growth. For each sample, phenology, total dry matter, leaf area index (LAI) and, at maturity, total dry matter, seed yield and harvest index, were recorded.
In both seasons, narbon vetch attained the highest dry matter and seed yields, and there was very limited variability in the maximum dry matter yield of the other entries. In general, the maximum dry matter occurred at 20–50 % podding in woolly pod vetch, 100 % podding in common vetch selection 2541 (local), narbon vetch and common chickling and at maturity in common vetch selection 2037, selection 2020 and ochrus chickling.
Throughout the vegetative to early flowering stages, woolly pod vetch had the highest dry matter yield and LAI. Possible uses of each species as animal feed are discussed. 相似文献
In both seasons, narbon vetch attained the highest dry matter and seed yields, and there was very limited variability in the maximum dry matter yield of the other entries. In general, the maximum dry matter occurred at 20–50 % podding in woolly pod vetch, 100 % podding in common vetch selection 2541 (local), narbon vetch and common chickling and at maturity in common vetch selection 2037, selection 2020 and ochrus chickling.
Throughout the vegetative to early flowering stages, woolly pod vetch had the highest dry matter yield and LAI. Possible uses of each species as animal feed are discussed. 相似文献
109.
渔船碰撞事故责任分析中应注意的若干问题 总被引:1,自引:0,他引:1
随着海洋渔业的发展,渔船数量不断增多,船舶间碰撞事故的发生也就难以避免了。渔港监督部门作为主管机关在受理碰撞事故后,必然要进行责任分析,明确双方当事船舶的责任分摊。本文依据《1972年国际海上避碰规则》,提出了渔船碰撞事故责任分析中应注意的若干问题,以便有关部门参考。 相似文献
110.
The major limiting factor to livestock production in West Asia and North Africa is the inadequate feed supply. The introduction of leguminous forage species into fallow lands represents a means of increasing feed supplies for the rapidly growing livestock population.
Twenty five lines each of common vetch ( Vicia sativa L.) wooly-pod vetch ( Vicia villosa ssp. dasycarpa Ten.), and bitter vetch ( Vicia ervilia L.) were tested over three seasons with contrasting rainfalls and winter temperatures. For each species, seedling vigour, winter growth, cold effect, spring growth, leafiness, herbage yield at 100 % flowering, grain yield, harvest index and aspects of herbage quality were recorded. There were considerable variation among entries with the same species, entries of V. ervilia were the earlier in flowering and maturity, and V. villosa ssp. dasycarpa almost the latest by 45 days. V. sativa , was the most affected by frost whilst both V. villosa ssp. dasycarpa and V. ervilia proved to be cold tolerant.
Although V. villosa ssp. dasycarpa produced high herbage yield in springs its grain yield is low resulting in a low harvest index. Both V. ervilia and V. sativa produced high grain yield with high harvest index. Seed yield was negatively correlated (P < 0.01) with days to flowering and maturity indicating the need of earlier types.
Quality of the herbage in term of digestibility was far lower (46 % IVDMD) in V. villosa ssp. dasycarpa than the other two species (69 % and 72 %).
The possible niches and utilization of each species as animal feed in the prevailing farming systems are discussed. 相似文献
Twenty five lines each of common vetch ( Vicia sativa L.) wooly-pod vetch ( Vicia villosa ssp. dasycarpa Ten.), and bitter vetch ( Vicia ervilia L.) were tested over three seasons with contrasting rainfalls and winter temperatures. For each species, seedling vigour, winter growth, cold effect, spring growth, leafiness, herbage yield at 100 % flowering, grain yield, harvest index and aspects of herbage quality were recorded. There were considerable variation among entries with the same species, entries of V. ervilia were the earlier in flowering and maturity, and V. villosa ssp. dasycarpa almost the latest by 45 days. V. sativa , was the most affected by frost whilst both V. villosa ssp. dasycarpa and V. ervilia proved to be cold tolerant.
Although V. villosa ssp. dasycarpa produced high herbage yield in springs its grain yield is low resulting in a low harvest index. Both V. ervilia and V. sativa produced high grain yield with high harvest index. Seed yield was negatively correlated (P < 0.01) with days to flowering and maturity indicating the need of earlier types.
Quality of the herbage in term of digestibility was far lower (46 % IVDMD) in V. villosa ssp. dasycarpa than the other two species (69 % and 72 %).
The possible niches and utilization of each species as animal feed in the prevailing farming systems are discussed. 相似文献