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131.
132.
乡村生态旅游是以乡村景观与乡村风情为主要吸引物的旅游活动,对于我国社会主义新农村建设,对于解决＂三农＂问题,是一个重要的切入点。而乡村生态旅游对于解决乡村发展中的环境问题,对于乡村旅游的可持续发展具有积极作用。本文阐述了乡村生态旅游的定义,分析了成都市周边乡村生态旅游类型、特点及功能,重点围绕乡村生态旅游发展的现状和存在问题,结合成都市创建世界田园城市,有针对性地提出了成都市周边乡村生态旅游开发的主要措施和建议。 相似文献
133.
本文报导23种广东常见阔叶树材的耐磨性试验结果,并对耐磨性与木材密度、硬度的关系及木材耐磨性各向异性问题作了讨论。 相似文献
134.
Dong Yuku Zhao Chunrui Northeast Forestry University 《林业研究》1991,2(1):83-90
In this paper,the physical and mechanical properties of important Chinese woodswere studied by using the methods of variable analysis, regression analysis,correlation analysis,principle component analysis and so on systematically.The results showed synthetical characteristicof the physical and mechanical properties of Chinese woods.Some opinions of former authors wererevised and some new laws were discovered.That is helpful to study of the physical and mechanicalproperties of woods. 相似文献
135.
分析海南热带植物园品牌塑造与推广的可行性与必要性,并提出建设热带植物王国,打造科技旅游精品,促进海南国际旅游岛建设等品牌建设的发展对策。 相似文献
136.
采用方差分析比较5种甲醛浓度[分别为Ⅰ (CK)、Ⅱ、Ⅲ、Ⅳ、Ⅴ]对虎尾兰、吊兰、袖珍椰子、白鹤芋、常春藤细胞质膜相对透性和光合特性的影响.结果显示,质膜透性随着甲醛浓度增加而提高,Ⅱ处理对5种植物质膜相对透性影响不显著,Ⅲ处理对吊兰质膜相对透性影响不显著而对其他4种植物质膜相对透性影响极显著,Ⅳ、Ⅴ处理对5种植物质膜相对透性影响极显著;Ⅱ处理提高植物的净光合速率(Pn)、除常春藤外其他4种植物的蒸腾速率(Tr)、气孔导度(Gs)和胞间CO2浓度(Ci),降低气孔限制值(Ls),植株生长良好,无受毒害症状;Ⅲ处理提高Ci,提高除了常春藤外其他4种植物的Pn、Tr和Gs,降低Ls,降低虎尾兰、吊兰、袖珍椰子的水分利用效率(WuE),虎尾兰、袖珍椰子、白鹤芋、常春藤植株长势一般,有轻微的受毒害症状,吊兰长势良好,无受毒害症状;Ⅳ、Ⅴ处理导致Pn下降,造成袖珍椰子、白鹤芋、常春藤的Tr和白鹤芋、常春藤的Gs下降.Ⅴ处理还引起虎尾兰、吊兰、白鹤芋的Ci下降和Ls提高,植株长势较差,有明显的受毒害症状.结果表明,虎尾兰、吊兰、袖珍椰子、白鹤芋、常春藤对甲醛的耐受力即阈值分别为1.335～2.367、2.370～5.150、1.374～2.523、1.326～2.287、1.354～2.482 mg/m3. 相似文献
137.
A significant effect of year on maize nutritive value has been reported in many studies; however, the direct effect of year on both nutritive values and fermentation traits of maize silage has not been directly investigated. During a 7‐year period (2006–2012), we investigated the following variables of 597 maize silages commercially produced in bunker silos on farms in the Czech Republic: dry‐matter content (DM), crude protein (CP), starch, amylase‐treated neutral detergent fibre (aNDF), acid detergent fibre (ADF) and net energy lactation (NEL), as well as fermentation traits such as pH, contents of lactic acid (LA), acetic acid (AA), butyric acid (BA) and the ratio between LA and volatile fatty acids. The effect of year and DM explained 16 and 30% of the variability in nutritive and fermentation traits respectively. Although a common silage DM content was used for each year, the climatic effect of year significantly changed almost all tested variables, but particularly aNDF, ADF, starch, AA and BA. The year contribution to trait variability effect was as much as two times higher for fermentation traits (12·6%) as for nutritive value (6·1%). Temperature–precipitation relationships associated with achieved maize yield were considered as factors explaining the year effect. Temperature and precipitation averaged over the full vegetation period had low relevance to nutritive and fermentation traits. This study reveals the importance of year‐to‐year variation in silage nutritive value and fermentation, which could be useful for understanding the contribution of year to these changes in both field experiments and national assessments. 相似文献
138.
139.
140.
Haoliang Chen Lulu Lin Minghui Xie Guangling Zhang Weihua Su 《Journal of insect science (Online)》2015,15(1)
Holotrichia oblita Faldermann (Coleoptera: Scarabaeidae) is a major pest both in field crops and forests because the larvae could eat the roots of most crops in the field, and the adults damage the leaves of trees and field crops. In this study, we focused on the effects of temperature on H. oblita reproductive parameters. The results indicated H. oblita female adults at 25°C could lay more eggs (84.0 eggs per female) and have the shortest preoviposition period (19.1 d), the greatest oviposition rate (2.8 eggs per female per 3 d), and largest percentage of life span spent in oviposition (59.5%). The longevity and the time to 50% egg laying decreased with increasing temperature, and female longevity was always longer than male longevity. The preoviposition and postoviposition period decreased with increasing temperature from 15 to 25°C and then increased when the temperature increased from 25 to 30°C. These results show that 25°C is the optimal temperature for reproduction of H. oblita. 相似文献