黄山松人工林球果生物量的测定

采取平均木法实测不同立地条件的 10年生黄山松球果生物量 ,阐明黄山松球果生物量与立地条件以及测树因子之间的相互关系。 10年生黄山松山脊球果生物量最高平均每株 0 5 8kg ,而山坡最低为 0 4kg。应用树高和胸径分别推导出预测黄山松球果生物量的回归方程。     

天然次生白桦林凋落物的分解及其生态效应

1988～1990年间以长白山支脉张广才岭帽儿山老爷岭生态站天然次生白桦林为研究对象,对林分凋落物的积累,组成与分解进行了定位观察研究。结果表明,38年生白桦林凋落物的现存量为13.644t/ha,其中叶为10.49t/ha,枝为2.58t/ha,树皮、种实、动物尸体及粪便等仅为0.57t/ha,年凋落盈为3.38t/ha,年分解量为0.633t/ha,年分解率为18.7％。     

白蜡虫优良种虫及种群性比组成的研究

白蜡虫(Ericerus pela Chavannes)是我国特产资源昆虫,国内产区很多。实验表明各产区繁育白蜡虫的产量与质量差异显著,其中以金沙江下游云、贵、川三省相接壤的白蜡虫产区,繁育的白蜡虫产卵数量多、雄卵比率高、产蜡时间长、产蜡量多,同时蜡虫的产量高,是我国白蜡虫的优良种虫。     

杨树不同无性系根系生长的比较

通过对20个杨树无性系的根系生长进行的比较及聚类分析研究,结果表明：20个杨树无性系不定根总长度和数量均具有较大的差异,其中,中驻1号不定根总长度最长,达到35.6 m,其次是 NL351、T26和中驻6号,最小的为109,仅为15.4 m。数量最大的也是中驻1号,共65根;中驻6号、W07和 I107次之;最小的为 W03和109,均为24根。基部直径在2 cm 以下的不定根占不定根总数量的60%~80%;聚类分析将20个杨树无性系分成6类。     

发达国家牛结核病根除计划的法律要点分析

完善有效的法规体系,是美、欧、澳根除牛结核病等动物疫病的基础保障。其要点主要包括：健全法律制度,强化财政支持,减少利益方抵触行为;规范检测方法,对屠宰牛进行全部检疫;对阳性牛实施严格追溯制度,并分类实施标识制度;建立病牛扑杀的基本标准,选择性采取扑杀措施;推行区域化管理制度,建立差异性市场准入标准;实施野生动物隔离及监测制度,防止野生动物向家养动物传播疫情;强化利益方的宣传教育,营建群防群控氛围。这些策略和措施,对我国健全结核病防治策略具有一定借鉴意义。     

The effects of replacement of whole‐plant corn with oat and common vetch on the fermentation quality,chemical composition and aerobic stability of total mixed ration silage in Tibet

The objective of this experiment was to evaluate the effects of replacement of whole‐plant corn with oat and common vetch on the fermentation quality, chemical composition and aerobic stability of total mixed ration (TMR) silage in Tibet. Four TMR that varied in the forage sources on dry matter basis were used: (i) 52% whole‐plant corn (Control); (ii) 43% oat + 12% common vetch (OC3.6); (iii) 38% oat + 18% common vetch (OC2.2); and (iv) 33% oat + 23% common vetch (OC1.5). Silos were opened on day 45 and then subjected to an aerobic stability test for 12 days. The results showed that all silages were well preserved with low pH and NH₃‐N, and high lactic acid and V‐scores. With the increasing proportion of common vetch, crude protein, ether extract increased (P < 0.05), and neutral detergent fiber and acid detergent fiber decreased (P < 0.05). Under aerobic conditions, treated silages were more stable than the control silage as indicated by lower (P < 0.05) pH and yeast population. It was concluded that replacement of whole‐plant corn with oat and common vetch had no unfavorable effects on the fermentation quality and improved crude protein content and aerobic stability of TMR silage. OC2.2 silage was the best among three treated TMR silages.     

Synthesis, insecticidal activity, and QSAR of novel nitromethylene neonicotinoids with tetrahydropyridine fixed cis configuration and exo-ring ether modification

To keep the nitro group in the cis position, a series of nitromethylene neonicotinoids containing a tetrahydropyridine ring with exo-ring ether modifications were designed and synthesized. All of the compounds were characterized and confirmed by 1H NMR, high-resolution mass spectroscopy, elemental analysis, and IR. The bioassay tests showed that some of them exhibited good insecticidal activities against pea aphids. On the basis of 10 nitromethylene derivatives, the quantitative structure-bioactivity relationship (QSAR) was analyzed and established. The results suggested that AlogP98 and Dipole_Mopac might be the important parameters related with biological activities.     

Development of an enzyme-linked immunosorbent assay for the detection of pentachloronitrobenzene residues in environmental samples

A competitive enzyme-linked immunosorbent assay (ELISA) for pentachloronitrobenzene (PCNB), a fungicide and chemical intermediate, was developed using a polyclonal antiserum produced against a hapten-protein conjugate of pentachlorophenoxypropionic acid-bovine serum albumin (BSA). An indirect competitive ELISA of PCNB showed an IC50 of 37 ng/mL and a limit of detection (LOD) of 7 ng/mL. The ELISA can tolerate up to 10% (v/v) methanol, 5% (v/v) acetonitrile, or 5% (v/v) acetone without significant fluctuation of Amax and IC50. The assay sensitivity showed little change in a range of pH from 6 to 8 and concentrations of 0.05-0.2 M NaCl in the assay buffer. Very low cross-reactivities were observed for some structurally related compounds except for hexachlorobenzene (12%). The average recoveries of PCNB from fortified well water, river water, and soil samples were in ranges of 88-94, 80-91, and 70-81%, respectively. The correlations between the gas chromatographic and ELISA results were excellent (r 2 >or= 0.97, slopes from 0.86 to 1.10) for those fortified samples. The ELISA is a good alternative tool for monitoring PCNB residues in environmental samples.     

百里香酚对鱼源耐药性维氏气单胞菌的体外抑菌效果及其机制研究

为探究百里香酚对鱼源耐药性维氏气单胞菌(Aeromonas veronii)的抑菌效果和作用机制,从患病黄颡鱼(Pelteobagrus fulvidraco)体内分离得到一株维氏气单胞菌,药敏试验结果显示,其对氟苯尼考、环丙沙星和恩诺沙星耐药。通过测定最低抑菌浓度(MIC)、最低杀菌浓度(MBC)和生长曲线来评价百里香酚对耐药性维氏气单胞菌的抑菌活性;通过测定百里香酚对其细胞膜通透性、可溶性蛋白、乳酸脱氢酶活性和DNA的影响,结合电镜观察细菌超微结构的变化研究其作用机制。结果显示,百里香酚对耐药性维氏气单胞菌的抑菌效果明显,MIC为256 μg·mL^-1,MBC为512 μg·mL^-1。经512 μg·mL^-1的百里香酚作用1 h后,维氏气单胞菌液电导率极显著(P<0.01)上升,DNA外渗量迅速上升至(115.6±0.5)mg·L^-1。经512 μg·mL^-1的百里香酚作用后,维氏气单胞菌的可溶性蛋白明显变少,细菌乳酸脱氢酶活性在2、4、6、8 h分别极显著(P<0.01)降低了(32.8±0.7)%、(46.2±0.3)%、(46.1±1.6)%、(60.0±1.0)%,DAPI(4',6-二脒基-2-苯基吲哚)染色的荧光强度和密度降低,电镜下可见菌体表面溶解塌陷,皱缩变形,细胞壁和细胞膜分离,细胞质丢失,内部空化。上述结果表明,百里香酚对维氏气单胞菌具有较强的抗菌活性,主要通过增加细胞膜通透性导致胞内物质流失造成细菌死亡。百里香酚可以作为治疗耐药性维氏气单胞菌感染的备选药物进行研究。