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排序方式: 共有492条查询结果,搜索用时 15 毫秒
71.
Do?Thi?XuanEmail author Vo?Thi?Guong Anna?Rosling Sadhna?Alstr?m Benli?Chai Nils?H?gberg 《Biology and Fertility of Soils》2012,48(2):217-225
Intensive cropping, especially of rice, is considered to contribute to negative effects not only on soil chemical and biological
properties but also on long-term grain yield. Appropriate crop rotation is often practiced as an alternative strategy to overcome
the negative side effects of intensive cropping. Although soil microbial diversity and community structure have been shown
to respond differently to altered agricultural management practices, little is known about possible links between crop rotation
and grain yield on bacterial communities in rice paddy soil. In this study, we investigated the impact of specific rotational
crops and compared it with intensive rice cultivation. The main crop rice (Oryza sativa) was rotated with maize (Zea mays) and mungbean (Phaseolus aureus) in different combinations in a system cultivating three crops per year. Soil bacterial communities were studied in two different
cropping periods using pyrosequencing of the variable V4 region of the 16S rRNA. Our results showed that rotation with alternative
crops increased rice yield by 24–46% depending on rotation structure and that bacterial community structure was altered in
the presence of mungbean and/or maize compared to that in rice monoculture. In the crop rotation systems, composition, abundance,
and diversity of soil bacterial communities were significantly different and higher than those in rice monoculture. Our results
show that effects of crop rotation relate to changes in soil bacterial community structure suggesting that appropriate crop
rotations provide a feasible practice to maintain the equilibrium in soil microbial environment for sustainable rice cultivation. 相似文献
72.
Chinh Chung Doan Thanh Long Le Nghia Son Hoang Ngoc Trung Doan Van Dong Le Minh Si Do 《Iranian Biomedical Journal》2014,18(2):67-75
Background: Stem cell therapy for the treatment of vascular-related diseases through functional revascularization is one of the most important research areas in tissue engineering. The aim of this study was to investigate the in vitro differentiation of umbilical CL-MSC into endothelial lineage cells. Methods: In this study, isolated cells were characterized for expression of MSC-specific markers and osteogenic and adipogenic differentiation. They were induced to differentiate into endothelial-like cells and then examined for expression of the endothelial-specific markers, karyotype, and functional behavior of cells. Results: Isolated cells expressed MSC-specific markers and differentiated into adipocytes and osteoblasts. After endothelial differentiation, they expressed CD31, vWF, VE-cadherin, VEGFR1, and VEGFR2 at both mRNA and protein level, but their morphological changes were not apparent when compared with those of undifferentiated cells. There were no significant changes in karyotype of differentiated cells. Furthermore, angiogenesis assay and LDL uptake assay showed that differentiated cells were able to form the capillary-like structures and uptake LDL, respectively. Conclusion: The results indicated that umbilical CL-MSC could differentiate into functional endothelial-like cells. Also, they are suitable for basic and clinical studies to cure several vascular-related diseases. Key Words: Endothelial differentiation, Endothelial-like cells, Mesenchymal stem cells, Umbilical cord lining membrane 相似文献
73.
以毛竹Phyllostachys edulis集成材为研究对象,在不同条件下进行高频热压,通过对竹集成材板坯高频热压过程中芯层温度变化的统计分析,得到了竹集成材高频热压过程中板坯温度的变化规律。结果表明:在试验条件范围内,随着板坯含水率从6%增加到18%,涂胶量从200 g·m-2增加到300 g·m-2,板坯的温度明显升高。升温过程可以分为快速升温和慢速升温2个阶段。在快速升温阶段板坯内的温度随板坯初含水率、涂胶量及加热时间的提高而递增;在慢速升温阶段板坯初含水率及涂胶量对板坯内的温度的影响很小,板坯芯层升温速度随加热时间的增加而减少。通过试验数据分析,得出较优的高频热压胶合工艺条件为:涂胶量300 g·m-2,竹条含水率12%,高频热压时间7 min。 相似文献
74.
基于SRTM_DEM的泾河流域特征信息提取研究 总被引:2,自引:0,他引:2
流域特征信息的提取对于水文地理信息分析、模拟技术和水文模型建立具有重要意义。基于STRM_DEM数据,在ArcGIS9.3环境下,提取泾河流域坡度、坡向等地形特征,以及河网、流域边界和面积等水文要素,并划分子流域。分析表明,当闽值取5000(40.5km^2)时,生成的流域河网能够较好地反映该地区水系。根据河网分级、低级集水区域生成结果和流域地形特征,可划分为32个子流域,为流域分布式水文模型的构建提供了基础地理信息。SRTM_DEM提取泾河和部分支流流域面积误差均较小,说明提取结果与实际非常接近。结果表明,SRTM_DEM数据和ArcGIS9.3提取流域特征信息方便快捷,具有较高的精度和准确性,应用前景广阔。 相似文献
75.
Nhung Thi Nguyen Nguyen Xuan Bui Viet Linh Nguyen Van Khanh Nguyen Kazuhiro Kikuchi Hiep Thi Nguyen Hong Thi Nguyen Hoang Thinh Nguyen Quyen Van Dong Hoang Ha Chu Ngo Thi Kim Cuc Tamas Somfai 《Animal Science Journal》2020,91(1)
The Vietnamese Ban pig is a precious genetic resource that needs to be preserved. In vitro embryo production from in vitro matured (IVM) oocytes is an important tool for the utilization of cryopreserved porcine sperm. The aim of this study was to compare two media for the IVM of Ban pig oocytes. Immature oocytes were subjected to IVM either in a non‐defined (TCM‐199 + pig follicular fluid) or in a defined base medium (POM + epidermal growth factor). At the end of IVM, the oocytes were in vitro fertilized (IVF) with frozen Ban sperm. Ten hours after IVF, the oocytes were either subjected to orcein staining to check fertilization and maturation status or cultured in vitro for 7 days. There was no difference between the two IVM media in terms of percentages of oocyte maturation and blastocyst production. However, the percentage of male pronuclear formation after IVF and the total cell numbers in blastocysts were higher with the defined system. Zygotes obtained by the two IVM systems survived vitrification at similar rates. In conclusion, the two IVM systems were both effective for the production of Ban pig embryos; however, better embryo quality was achieved with the defined one. 相似文献
76.
Nguyen Thi Thuy Man Dorny Pierre Lebailly Philippe Le Thi Minh Chau Nguyen Thi Thu Huyen Dermauw Veronique 《Tropical animal health and production》2020,52(6):2799-2808
Tropical Animal Health and Production - In Vietnam, pork is the most commonly consumed type of meat, and the demand is expected to rise even further. Nevertheless, food safety is a major concern,... 相似文献
77.
Olesya I. Zhuravleva Alexandr S. Antonov Vo Thi Dieu Trang Mikhail V. Pivkin Yuliya V. Khudyakova Vladimir A. Denisenko Roman S. Popov Natalya Y. Kim Ekaterina A. Yurchenko Andrey V. Gerasimenko Anatoly A. Udovenko Gunhild von Amsberg Sergey A. Dyshlovoy Shamil S. Afiyatullov 《Marine drugs》2021,19(1)
Seven new deoxyisoaustamide derivatives (1–7) together with known compounds (8–10) were isolated from the coral-derived fungus Penicillium dimorphosporum KMM 4689. Their structures were established using spectroscopic methods, X-ray diffraction analysis and by comparison with related known compounds. The absolute configurations of some alkaloids were determined based on CD and NOESY data as well as biogenetic considerations. The cytotoxic and neuroprotective activities of some of the isolated compounds were examined and structure-activity relationships were pointed out. New deoxyisoaustamides 4–6 at concentration of 1 µM revealed a statistical increase of PQ(paraquat)-treated Neuro-2a cell viability by 30–39%. 相似文献
78.
Context
The effects of agricultural intensification on service-providing communities remain poorly studied in perennial cropping systems. However, such systems differ greatly from annual cropping systems in terms of spatio-temporal dynamics and levels of disturbance. Identifying how land use changes at different scales affect communities and ecosystem services in those habitats is of major importance.Objectives
Our objectives were to examine the effects of local and landscape agricultural intensification on ground beetle community structure and weed seed predation services.Methods
We examined the effects of local vegetation management and landscape context on ground beetle community structure and weed seed predation in 20 vineyards of southwestern France in 2013 and 2014. Vineyards were selected along a landscape complexity gradient and experienced different management of local vegetation.Results
The activity-density of ground beetles decreased with increasing landscape complexity while species richness and evenness remained unchanged. Phytophagous and macropterous species dominated ground beetle communities. Seed predation was positively related to the activity-density of one species, Harpalus dimidiatus, and was not affected by local management or landscape context. We found that within-year temporal diversity in ground beetle assemblages increased with landscape complexity.Conclusions
Our study shows that increasing the proportion of semi-natural habitats in vineyard landscapes enhances the temporal diversity of ground beetles. However, we also found that measures targeting specific species delivering biological control services are a reasonable strategy if we are to maximize natural pest control services such as weed seed regulation to support crop production and reduce agrochemical use.79.
Dung Viet Pham Munehide Ishiguro Ha Thu Thi Tran Tsutomu Sato 《Soil Science and Plant Nutrition》2013,59(3):356-366
AbstractSoil dispersion induces soil erosion and colloidal leaching. Nutrients are lost at the same time and this causes water contamination. Phosphate is an essential element for living organisms. Because phosphate influences soil dispersion and it is an important limited resource, this influence must be evaluated well in order to diminish negative effects on soil structure. In this paper, we firstly evaluated the influence of phosphate sorption on soil dispersion by calculating repulsive potential energy between soil particles. Ferralsol, which is a typical soil in rainy tropical regions, was used as the material. The dispersion-flocculation phenomena were investigated with absorbance of soil suspension under different pH, phosphate adsorption and electrolyte concentration in an Na-NO3-PO4 system. The repulsive potential energy was calculated based on the diffuse double layer theory and the measured zeta potential. We indicated that the measured absorbance increased with the increase of the repulsive potential energy. The repulsive potential energy increased with increasing phosphate sorption up to about 5 to 20 mmol kg?1 at all pH, and it induced the soil dispersion, because phosphate sorption increased the negative charge of the soil. After its peak, it decreased with increasing phosphate sorption because the electrolyte concentration increased and the electrolyte screened the electric field near the soil surface. The repulsive potential energy also increased with increasing pH because of the increase of the negative charge of the soil. Even at low pH, after a certain amount of phosphate sorption, the soil dispersed due to the increase of repulsive potential energy, although the soil flocculated before phosphate application. Because the soil dispersion causes soil and phosphorus loss, the influence of soil pH and phosphate sorption on the soil dispersion should be considered for good soil management. 相似文献
80.
Kil Eui-Joon Ho Phuong Thi Fadhila Chairina Lal Aamir Vo Thuy Thi Bich Kim Mikyeong Lee Sukchan 《植物病害和植物保护杂志》2021,128(4):1091-1099
Journal of Plant Diseases and Protection - Plum pox virus (PPV) is a plant virus (genus Potyvirus, family Potyviridae) infecting stone fruit trees. Since the first report from Bulgaria in 1917, PPV... 相似文献