全文获取类型
收费全文 | 377篇 |
免费 | 24篇 |
国内免费 | 14篇 |
专业分类
林业 | 33篇 |
农学 | 26篇 |
基础科学 | 32篇 |
37篇 | |
综合类 | 215篇 |
农作物 | 10篇 |
水产渔业 | 3篇 |
畜牧兽医 | 21篇 |
园艺 | 33篇 |
植物保护 | 5篇 |
出版年
2023年 | 14篇 |
2022年 | 12篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 15篇 |
2015年 | 13篇 |
2014年 | 26篇 |
2013年 | 32篇 |
2012年 | 43篇 |
2011年 | 38篇 |
2010年 | 23篇 |
2009年 | 14篇 |
2008年 | 23篇 |
2007年 | 24篇 |
2006年 | 30篇 |
2005年 | 7篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 8篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 7篇 |
1997年 | 1篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1975年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有415条查询结果,搜索用时 15 毫秒
1.
Daniela Alvarado-Camarillo Ana María Castillo-González Juana C. García-Santiago 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2018,68(6):496-504
Purpose: Nitrogen (N) / potassium (K) nutrient balance has been studied for some ornamental plants, however, available information is limited. Here we investigate the optimum N and K balance and concentration for lisianthus production in soilless medium.Materials and methods: The effect of three N / K balances: 1.43, 2.14 and 4.29, prepared by varying the concentration of N and K, were evaluated in lisianthus grown in soilless medium (volcanic rock).Results: Plants fertigated with a N / K balance of 2.14 exhibited enhanced height and stem dry weight when compared to plants fertigated with a balance of 4.29, and a higher flower buds count and total dry weight than those fertigated with a balance of 1.43 or 4.29. Plants fertigated with a balance of 2.14 exhibited increased dry weight when N was reduced from 15 to 9?meq?L?1 and K from 7 to 4.2?meq?L?1, suggesting that lisianthus does not require high levels of these nutrients. Although shoot N concentration was not correlated with N concentration in the nutrient solution or balance, increasing N in the shoot was associated with higher P and Mg in the plant tissues. In general, P, Ca, and Mg in plant tissues were unaffected by the external N / K balance, however, the internal P and Mg concentrations were positively correlated with shoot dry weight. Shoot K concentration significantly increased when the N / K balance decreased, which is related to the higher concentrations of external K when the balance decreased.Conclusions: The optimum N / K balance for lisianthus was 2.14. However, there was a concentration effect, as fertigation with solutions containing a N / K balance of 2.14 and an N and K concentration of 9 and 4.2?meq?L?1 respectively, resulted in plants with the greatest dry weight. 相似文献
2.
本文从什么是新型职业农民,重点阐述睢县新型职业农民培育的现实状况,分析新型职业农
民培育中存在的问题,提出了培育新型职业农民要构建多元化培训模式的方案,理论培训与实际操作
相结合,跟踪考察落实情况并不断改进,将新型农民培养定为农村发展的战略性举措。 相似文献
3.
4.
F. Kobayashi 《Crop Protection》2011,30(11):1514-1518
To establish a method for disinfecting hydroponic culture solutions using ozone microbubbles (OMB), we examined the disinfectant activity of OMB against Fusarium oxysporum f. sp. melonis and Pectobacterium carotovorum subsp. carotovorum in infected plant roots. OMB had a higher solubility and remained in the water for a longer period than ozone millibubbles, resulting in extremely high disinfecting activity against both phytopathogens. Furthermore, disinfectant activity and durability of OMB-treated water against both phytopathogens increased with an increase in the initial concentration of dissolved ozone. Therefore, these results suggest that OMB may be suitable for use as a new disinfectant against phytopathogens in hydroponic culture solutions. 相似文献
5.
6.
7.
吴欣锟 《西南大学学报(自然科学版)》2018,40(12):120-125
在已有的变分不等式、可微变分不等式、分数阶可微变分不等式的模型的基础上,对一类新的带有参数δ∈[1,2)的分数阶可微变分不等式模型的解的存在性进行了相关的分析和研究.首先,在已有的分数阶可微变分不等式的模型基础上加了一个参数δ∈[1,2),得到了一类新的带有参数δ∈[1,2)的分数阶可微变分不等式模型,对这类新模型给出了详细的阐述;然后证明出该模型的解是非空的. 相似文献
8.
Probir Kumar Ghosh Satadal Das 《The Journal of Horticultural Science and Biotechnology》2017,92(2):130-145
Tuberose cut flowers, available as loose flowers, were treated with gamma (γ) irradiation and generally regarded as safe (GRAS) preservative solutions for extension of shelf life. The flowers were packaged in low-density polyethylene bags, heat sealed and stored at 23 ± 2°C, 80% relative humidity (RH) and 4 ± 1°C, 40% RH, respectively. The flowers stored at these two temperature regimes were subjected to sensory evaluation and biochemical analyses. From these assessments, the longest shelf life of tuberose flowers was found to be 8 days at 23 ± 2°C, 80% RH (compared to 4 days for control) and 24 days at 4 ± 1°C, 40% RH (compared to 8 days for control) using combination treatment of low dose γ-irradiation (0.02 kGy) and preservative solutions (4% sucrose and 0.02% CaCl2). Ethanolic extract of tuberose flowers of the most shelf stable set (stored at 4 ± 1°C), i.e. at the end of 24 days, showed antimicrobial potency against the common skin pathogen Staphylococcus aureus (ATCC 25923 and MDR strains), suggesting utility of the senesced tuberose flowers for therapeutic applications. This preservation technique would promote export of tuberose flowers by extension of their shelf lives and allow utilization of these flowers, post senescence. 相似文献
9.
林业行政违规现象的探讨 总被引:1,自引:0,他引:1
调查了林业行政管理中存在利益驱动、以罚代批、一罚了之、以权谋私、毁林造林、收取贿赂等6种违规形式,林业行政违规是行政职能部门的权力异化导致的。对违规成因进行了理论分析,提出应加强内、外监管,建立权力监督制约机制,民间团体、检察机关介入监管林业行政违规的解决对策。 相似文献
10.
承重墙体出现裂缝的原因是多方面的,本文针对地基不均匀沉降使墙体产生裂缝,结合工程实例,说明裂缝处理的施工过程及采取的补强方法。 相似文献