用迭代法分析计算机床静压轴承-主轴系统的静态性能

本文参照文献[1] 的基本路线思路,构造了静压轴承--主轴系统的迭代计算方法。并联系机床中非常普遍的弹性两支承外伸轴系,以一台 MB1520型高速外圆磨床为例,考虑到该主轴系统径向轴承及推力轴承综合作用,用迭代法分析计算了该主轴部件的静态性能,一般情况下只需迭代1～3次,就可获得满意的结果。该方法计算效率高,占用计算机内存小,能在袖珍计算机上运算,为普及对机床主轴系统的静、动态特性研究及优化设计,提供了行之有效的方法。     

论毛竹丰产林基地建设

论述了福建省龙岩市发展毛竹丰产林基地的自然优势,以及毛竹丰产林基地的形式与标准,改造现有低产毛竹林的措施,并根据不同的经营目的,论述了材用毛竹林、笋竹两用毛竹林、手工纸用毛竹林的丰产培育措施,毛竹丰产林基地的科学管理,包括机构建立,资料档案建立,竹林结构调整和病虫害防治等。     

优质高产抗病新品种新陆早18号及高产栽培技术

着重介绍新陆早18号的品种特性、产量性状、纤维品质及抗逆性,并主要阐述新陆早18号的高产栽培技术。     

Land Cover Type and Fire in Portugal: Do Fires Burn Land Cover Selectively?

The purpose of this study is to investigate if, or under what conditions, fires select given land cover types for burning. If fires burn unselectively then the land cover composition (the proportional area of various land cover types) of individual fires should approximate the land cover composition available in their neighborhood. In this study we test this hypothesis by performing statistical analyses of a data set consisting of paired vectors with the proportions of land cover types present in burned areas and in their respective surroundings. The statistical methods employed (a permutation technique and the C_max statistic) are commonly used in resource selection studies where data is subject to a unit-sum constraint. The results of the analysis of 506 fires that burned in Portugal in 1991 indicate that fires are selective, with small fires exhibiting stronger land cover preferences than large fires. According to the results of a multiple comparison analysis performed for small fires, there is a marked preference for shrubland followed by other forest cover types, while agriculture is clearly avoided. A similar analysis is performed to test if fire selectivity is related to the ecological region where it occurs. The results obtained in this study contribute to the discussion on the relative importance of fuels as a drivers of fire spread.     

Comparison of 3 techniques for ureteroneocystostomy in cats

OBJECTIVE: To compare 3 techniques for ureteroneocystostomy in cats. STUDY DESIGN: Experimental surgical study. ANIMALS: Fifteen adult cats. METHODS: Cats (15) had ureteroneocystostomy with ureteronephrectomy of the contralateral kidney: 5 cats had an intravesical mucosal apposition technique (modified Leadbetter-Politano; intravesical-MA group), 5 cats had extravesical ureteroneocystostomy (modified Lich Gregoir) using a simple continuous suture pattern (extravesical-SC group) and 5 cats had an extravesical technique using a simple interrupted suture pattern (extravesical-SI group). Renal function was evaluated by measuring serum creatinine concentration. Ultrasonographic assessment of the kidney and ureteroneocystostomy site was performed the day after surgery, twice weekly for 3 weeks and once weekly for the remainder of the study. Cats were euthanatized 50 days after surgery. The kidney and ureter removed at surgery, the remaining kidney, ureter, ureteroneocystostomy site, and bladder were examined histologically. RESULTS: Two extravesical-SC cats were euthanatized because of azotemia and uroabdomen, and 1 died acutely at day 4 for unknown reasons. In the intravesical-MA and extravesical-SI cats, the serum creatinine concentration increased after surgery, peaking at a mean (+/-SD) of 9.4+/-2.4 mg/dL and 4.9+/-3.3 mg/dL on day 3, and decreasing to 3.4+/-5.7 mg/dL and 1.5+/-0.4 mg/dL on day 7, respectively. The extravesical-SI technique was associated with consistently lower serum creatinine concentrations for the first week after surgery compared with the other techniques. The mean serum creatinine concentration was within the reference range in cats in the intravesical-MA and extravesical-SI groups by days 10 and 5, respectively. Renal pelvic dilatation occurred in all cats but resolved more rapidly in cats after extravesical techniques. There was no significant difference in serum creatinine concentrations or renal pelvic dilation between the intravesical-MA and extravesical-SI techniques. Bladder mass height at the anastomosis site was significantly larger and persisted for longer with intravesical-MA technique. CONCLUSION: An extravesical-SI technique is seemingly the choice for ureteroneocystostomy in cats with undilated ureters. Renal pelvic dilation on ultrasound examination should be expected after ureteroneocystostomy in cats. CLINICAL RELEVANCE: An extravesical ureteroneocystostomy technique using a simple interrupted pattern for anastomosis should be considered in cats undergoing renal transplantation.     

宁夏沙地葡萄栽培配套技术应用研究

在宁夏沙地葡萄栽培中采用以根区挖沟换土的土壤改良技术,节水滴灌技术,以抗寒防冻为目的的建园和栽培技术,以生产绿色食品为标准的规范化树体管理技术等一整套新技术,使宁夏沙地葡萄生产达到了优质丰产的水平,经济效益显著.     

Three cases of prolapse of the nictitans gland in cats

We report three cases of adult cats showing a prolapse of the gland of the third eyelid. Three different breeds were affected: Burmese, Persian and Domestic Short-haired. In all cases, the disorder occurred spontaneously, without any other ocular sign. Surgical replacement of the gland was performed using the Morgan pocket technique. Good esthetic results were obtained, and no recurrence occurred.     

槐豆木虱若虫空间分布型及抽样技术研究

应用6种分布型指数法分析判定了槐豆木虱[Cyamophila willieti(Wu)]若虫在国槐(Sophora japonicaLinnaeus)上的空间分布型,利用Taylor(1961)幂法则和Iwao(1971)回归方程分析聚集原因,结果表明,槐豆木虱若虫在国槐上呈聚集分布,公共kc值为5.159 0,且符合负二项分布;其种群聚集原因是由昆虫本身行为习性所致。在此基础上,采用Iwao的方法确定了槐豆木虱若虫的田间理论抽样数和序贯抽样表。     

大螟蔗田枯心苗的空间分布型及抽样技术研究

为了确定大螟蔗田枯心苗的空间分布型与抽样技术,采用聚集度指标法、Iwao回归分析法和Taylor幂法则分析了甘蔗枯心苗的空间分布型,根据Iwao的理论抽样数模型确定了蔗田枯心苗的最适理论抽样数。甘蔗枯心苗的空间分布呈聚集分布,基本成分是个体群,个体间相互吸引,个体群在蔗田呈聚集分布。聚集程度随密度的升高而增加,聚集原因可能是由于甘蔗自身特性和大螟为害等环境因子作用或其中一个原因引起的。5种抽样方法均可用于蔗田抽样调查。用Iwao的理论抽样数模型计算出蔗田枯心苗的理论抽样数模型为:D=0.1时,n=230.470 0/m+0.980 0,D=0.2时,n=57.617 5/m+0.245 0,D=0.3时,n=25.607 8/m+0.108(m为枯心苗平均密度)。本文为开展大螟测报和防治提供了理论依据。     

林木害虫监测技术的研究进展

随着国际间贸易的频繁,外来林木害虫传入我国的风险加大,评估外来林木害虫扩散趋势和速度,建立有效的外来林木害虫监测系统显得尤为迫切。本文结合本课题组有关林木害虫诱集已取得的成果,综述了近年来国内外对外来林木害虫诱集监测技术的研究进展,并就建立适合我国的外来林木害虫监测体系提出建议。