全文获取类型
收费全文 | 58篇 |
免费 | 13篇 |
国内免费 | 5篇 |
专业分类
林业 | 7篇 |
农学 | 8篇 |
基础科学 | 6篇 |
16篇 | |
综合类 | 23篇 |
农作物 | 4篇 |
水产渔业 | 4篇 |
畜牧兽医 | 4篇 |
园艺 | 2篇 |
植物保护 | 2篇 |
出版年
2024年 | 1篇 |
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 9篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 2篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 2篇 |
2007年 | 2篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2003年 | 1篇 |
2002年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1995年 | 2篇 |
1991年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有76条查询结果,搜索用时 187 毫秒
1.
珍贵大径级材是我国重要的战略资源。探讨了珍贵大径级材在安徽省培育的意义及有利条件等,并提出了相应的政策措施和技术路线。 相似文献
2.
Cheng Qing Zhou Chao Ng Charles Wang Wao Tang Chaosheng 《Journal of Soils and Sediments》2020,20(2):756-762
Journal of Soils and Sediments - Temperature has a significant influence on water retention curve (WRC) because temperature affects surface tension of water and volumetric behaviour of soil.... 相似文献
3.
The genetic improvement of wood properties is one of the important measures of improving wood quality. To achieve that, forestry and wood scientists have done a great deal of research in expectation to produce more high-quality wood. The paper summarizes the researches on genetic variation and genetic correlation of wood properties and proposes the prospects to conduct the genetic improvement of wood properties. 相似文献
4.
Weijun Fu Zhuojing Fu Hubert Tunney Chaosheng Zhang 《Archives of Agronomy and Soil Science》2013,59(10):1459-1466
Field-scale variation of soil phosphorus (P) information is very important for P fertilizer application and its soil sampling design in grassland. A total of 108 soil samples were collected from a long-term (41 years) grazed grassland P experiment field at Teagasc, Johnstown Castle, Wexford, Ireland, in March 2009. There were six P treatments (P0-0, P0-30, P15-15, P15-5, P30-30, and P30-0) since 1968, with changes since 1999. Each treatment had 6 replicate plots (a total of 36 plots, 3 soil samples per plot). The samples were analyzed for available (Morgan’s) P, potassium (K), magnesium (Mg), lime requirement (LR), and pH. The highest mean available P concentration was found in the P30-30 (30 kg P ha?1 pre- and post-1998) plots, and the lowest mean available P concentration was found in the P0-0 (no P fertilizer since 1968) plots. Significant differences of mean P, Mg, LR, and pH values in different treatments were observed. There was a positive proportional effect for both the 36 plots and the 6 treatments for the P data: the local standard deviation increased with the increase of local mean. The proportional effect should be considered in order to optimize sampling design. Fewer samples can reflect soil P status in fields with low soil P levels, while more attention should be paid to the fields with high P levels in order to reduce environmental consequences of uniform applications. 相似文献
5.
数据结构是计算机专业的重要课程,其中涉及到大量复杂的算法,而算法恰恰是数据结构教学中的难点。本文阐述借助Flash软件如何将这些抽象而复杂的算法形象的表达出来,从而实现数据结构算法的动态演示。 相似文献
6.
用选自陆海杂交后代的抗蚜选系抗77为母本与具中棉亲缘的丰产品种江苏棉1号杂交,后代与父本江苏棉1号回交2次,经20代综合鉴定和多性状定向选育的川棉109。该品种抗棉蚜,抗枯萎病和立枯病,耐黄萎病,耐旱,抗倒,耐瘠薄;并克服了陆地棉密茸毛与短纤维的连锁,将抗虫与抗病、丰产与优质有机组合;综合性状鉴定为国内领先和国际先进水平.目前己累积推广27万hm2,是利用多质资源培育多抗型丰产品种的实例。多质资源是前提,多抗性、强生长势、强补偿力等构成了川棉109丰产稳产的综合遣传优势。启示育种目标日趋综合的现代棉花育种应选择宽广的质源,培育多抗性取代单抗性,并以胁迫和非胁迫双重条件下的产量比较为核心,实现抗性与丰产性的统一。 相似文献
7.
8.
本文主要介绍了南宋梁楷、李嵩,明代仇英、宋宗鲁,清代冷枚、陈枚、何太青以及袖珍型等八种目前比较鲜见的《耕织图》,并分别就其内容作了一些比较和分析,对《耕织图》的发展和演变作了分析。以此作为对《中国古代耕织图》一书的部分读者所提问题的释疑。 相似文献
9.
10.
Weijun?Fu Keli?ZhaoEmail author Chaosheng?Zhang Jiasen?Wu Hubert?Tunney 《Precision Agriculture》2016,17(2):121-135
Outliers are classified as global outliers and spatial outliers. Up to now, there is little information about the outliers especially the spatial outliers and their influence on the spatial structure modeling of soil properties. A total of 537 soil samples were collected based on a 30 × 30 m grid in a permanent dairy farm in southeast Ireland. Graphic methods of histogram and box plot combined with Moran’s I were applied to detect the outliers of soil phosphorus (P). Sixteen outliers (5 global outliers and 11 spatial outliers) of soil P were found in the study area. Compared to the raw data, the data with global outliers excluded always had the larger global Moran’s I value indicating a stronger spatial autocorrelation. Clear spatial clusters (High–High and Low–Low clusters) were observed based on local Moran’s I. The High–High spatial clusters were located around the main farm yard and near the traffic route due to more intensive management by farmers. The Low–Low spatial clusters were mainly close to the river. For these areas, P fertilizer or slurry should be applied for healthy grass growth. The dataset with outliers excluded had a reliable semi-variogram model with a low nugget/sill ratio (32.4 %), which was closed to its corresponding transformed data (30.5 %). The cross-validation results revealed that the dataset without outliers had the strongest linear regression model (r = 0.768), indicating that the outliers played an important role in the spatial structure modeling. 相似文献