武夷山丝栗栲天然林群落的生物量及其分配规律

采用标准木法(乔木层)及样方收获法(灌木层、草本层),研究了武夷山自然保护区丝栗栲天然林的生物量及其分配规律。结果表明:森林总生物量为312.082 t/hm2,其中树干为172.968 t/hm2(55.42%),枝为40.677 t/hm2(13.04%),叶为10.199 t/hm2(3.27%),根为67.485 t/hm2(21.62%),生物量绝大部分积累于乔木层(78.99%)。群落各组成树种中丝栗栲占显著优势,浙江润楠、黄瑞木、树参、虎皮楠等为群落重要伴生树种,制约和影响着群落的结构和生境。     

抚育改造是森林生态系统经营的关键性措施

该文阐述了森林生态系统经营的概念及其目标,抚育改造在森林生态系统经营的地位与作用,并提出抚育采伐与主伐的融合、抚育与改造的结合是森林生态系统经营体系的发展趋势.中国正在实施天然林保护工程与解决人工林地力衰退问题,急需搞好森林的抚育改造.通过对国内外的实践进行分析,作者认为:林业的可持续发展依赖于森林资源的持续,森林资源的持续依赖于森林的科学经营.森林生态系统经营将是21世纪森林经营模式的最佳选择,而抚育改造则是森林生态系统经营的关键性措施.      

育肥期肉猪日粮添加糖萜素的效果研究

选用82日龄29.76±0.52 kg体重育肥猪57头,随机分为2组,试验组27头和对照组30头,每组设3个重复,试验组日粮中添加糖萜素,对照组日粮中添加抗生素及砷制剂,试验期78 d,研究糖萜素对肉猪肥育期的影响.试验结果表明:与对照组相比较,试验组日增重降低7.46%(P＜0.05)、饲料转化率提高(P＞0.05)、腹泻率提高1.77%(P＞0.05),综合经济效益显著.     

高压直流接地极对埋地管道的干扰监测及影响规律

为了掌握高压直流输电工程接地极对埋地管道杂散电流干扰的影响规律,在17个高压直流输电工程接地极附近的12条管道上安装了电位远程监测系统,对管道电位进行长时间连续监测.通过管道电位变化分析接地极的干扰频次和干扰时间,以及管道受干扰程度、影响范围.监测结果显示:通过对管道电位长时间连续监测能够准确判断出接地极对管道的干扰影...     

Antiplatelet and Antithrombotic Effects of Isaridin E Isolated from the Marine-Derived Fungus via Downregulating the PI3K/Akt Signaling Pathway

Isaridin E, a cyclodepsipeptide isolated from the marine-derived fungus Amphichorda felina (syn. Beauveria felina) SYSU-MS7908, has been demonstrated to possess anti-inflammatory and insecticidal activities. Here, we first found that isaridin E concentration-dependently inhibited ADP-induced platelet aggregation, activation, and secretion in vitro, but did not affect collagen- or thrombin-induced platelet aggregation. Furthermore, isaridin E dose-dependently reduced thrombosis formation in an FeCl₃-induced mouse carotid model without increasing the bleeding time. Mechanistically, isaridin E significantly decreased the ADP-mediated phosphorylation of PI3K and Akt. In conclusion, these results suggest that isaridin E exerts potent antithrombotic effects in vivo without increasing the risk of bleeding, which may be due to its important role in inhibiting ADP-induced platelet activation, secretion and aggregation via the PI3K/Akt pathways.     

Saccharobisindole,Neoasterric Methyl Ester,and 7-Chloro-4(1H)-quinolone: Three New Compounds Isolated from the Marine Bacterium Saccharomonospora sp.

Analysis of the chemical components from the culture broth of the marine bacterium Saccharomonospora sp. CNQ-490 has yielded three novel compounds: saccharobisindole (1), neoasterric methyl ester (2), and 7-chloro-4(1H)-quinolone (3), in addition to acremonidine E (4), pinselin (5), penicitrinon A (6), and penicitrinon E (7). The chemical structures of the three novel compounds were elucidated by the interpretation of 1D, 2D nuclear magnetic resonance (NMR), and high-resolution mass spectrometry (HRMS) data. Compound 2 generated weak inhibition activity against Bacillus subtilis KCTC2441 and Staphylococcus aureus KCTC1927 at concentrations of 32 μg/mL and 64 μg/mL, respectively, whereas compounds 1 and 3 did not have any observable effects. In addition, compound 2 displayed weak anti-quorum sensing (QS) effects against S. aureus KCTC1927 and Micrococcus luteus SCO560.     

辣木内生真菌的分离及其抗菌活性物质的初步研究

从辣木中分离得到1株内生真菌ly14,其发酵液对金黄色葡萄球菌、绿脓杆菌和掷孢酵母有很强的抗菌作用．该菌发酵液中的抗菌物质对温度、pH及紫外线照射有较强的稳定性;ly14代谢物的理化特性表明,抗菌物质为极性酸性化合物,其紫外可见吸收光谱在276nm处出现了一个较为明显的吸收峰．     

长沙黑麋峰冬季鸟类资源调查及多样性分析

通过对黑麋峰森林公园鸟类资源的初步调查,共鉴定鸟类28种,隶属于5个目,15个科,25个属。公园内的Shannon-Wiener指数为0.864 6,均匀度指数为0.597 5。同时,用G-F指数对该地区鸟类的科与属的多样性指数进行了分析,得出G指数为1.374 5,F指数为1.586 2,G-F指数为0.133 5。与湖南其它几个地区的鸟类多样性相比,黑麋峰的鸟类多样性较低,并进一步分析了其鸟类多样性低的原因。     

昆虫病原真菌在害虫防治中对天敌生物的影响研究进展

昆虫病原真菌是一类重要的微生物杀虫剂,广泛应用于农林害虫的生物防治。由于寄主范围广和主动侵染的特点,昆虫病原真菌在侵染、致死靶标害虫的同时,对包括天敌昆虫在内的非靶标节肢动物等会产生潜在的致病或亚致死风险。本文总结了昆虫病原真菌在害虫防治中的研究进展及对天敌生物的影响,并展望了昆虫病原真菌作为极具潜力的生物农药与天敌生物联合防治害虫的未来发展方向。     

控制小菜蛾的赤眼蜂田间种群保护与增殖研究

通过建立十字花科蔬菜间作甜玉米、黑光灯诱虫育蜂笼这2种田间保护增殖措施,探讨了玉米螟赤眼蜂Trichogramma ostriniae、拟澳洲赤眼蜂T.confusum以及卷蛾分索赤眼蜂Trichogranunatoidea baarae对小菜蛾Plutella xylonella种群数量控制的作用．结果表明：十字花科蔬菜地间作甜玉米使得玉米螟赤眼蜂对小菜蛾卵寄生率有明显的提高,为4．62％～11．47％;黑光灯诱虫育蜂笼的设立对田间小菜蛾卵寄生蜂的种群数量起到了良好的增殖作用,自2002年4月初到6月底,诱集小菜蛾产卵127300粒,培育卷蛾分索赤眼蜂10万多头．在育蜂笼设立初期,笼内小菜蛾卵的寄生率为87．34％,距笼5m之外其寄生率急剧下降,其有效扩散范围不超过20m．2个月后的调查表明,赤眼蜂可逐步扩散到离育蜂笼30m处,各调查点之间寄生率的差距逐渐缩小,在距笼25m范围内,小菜蛾卵的寄生率维持在50％以上,有效地抑制了小菜蛾种群数量的增长．