浅谈钢筋混凝土框架结构设计

结合钢筋混凝土结构的应用特点、从混凝土结构中框架结构在地震作用下的结构体系到构造要求,阐明在设计混凝土结构时,不但要满足受力计算要求,更要注意抗震要求。     

苦瓜劈接嫁接夹固定嫁接技术

苦瓜是我国主要蔬菜经济作物之一,采用优良砧木进行劈接嫁接夹固定法嫁接,是实现高产优质的重要途径。该文就苦瓜砧木和接穗的选择、育苗、嫁接和嫁接后的管理进行了介绍,以为苦瓜嫁接育苗提供参考。     

农用地分等与定级估价研究--以呼和浩特市清水河县为例

在认识清水河县自然、社会经济条件的基础上,对清水河县农用地质量特别是耕地质量进行评定,探讨农用地分等与定级估价计算模型及方法,为加强农用土地资源管理与土地资产管理打下良好基础。     

莴笋根部促生菌筛选与促生特性测定

为获得莴笋(Lactuca sativa)根部优良促生菌株,为后续研制微生物接种剂(菌肥)提供优良菌种,以莴笋根系为对象,利用选择性培养基分离、筛选莴笋根系溶解有机溶磷、无机溶磷细菌和固氮细菌,测定其溶磷能力、固氮能力、分泌植物生长激素能力以及对植物病原菌的拮抗能力;对性能优良的菌株进行16S rDNA分子生物学鉴定。研究表明:莴笋根部分离到25株溶磷菌株,其溶解无机磷能力为60.83～290.66μg·mL~(-1)(菌株PGBA2溶磷量最高,为290.66μg·mL~(-1)),溶解有机磷的能力普遍较低,为8.12～71.87μg·mL~(-1);分离出固氮菌株20株,固氮酶活性为8.37～371.54 nmol·h~(-1)·mL~(-1)(GNB6固氮酶活性最强,为371.54 nmol·h~(-1)·mL~(-1));分离筛选分泌植物生长激素(IAA)菌株14株,分泌量为0.78～5.29μg·mL~(-1)(MGBD1分泌IAA的能力最强,为5.29μg·mL~(-1));菌株MGNB4、MGBC3、PGBA2对黄瓜枯萎病(Fusarium oxysporum)有抑菌作用,抑菌率达到50%以上。对9株优良PGPR菌株进行分子生物学鉴定,菌株MGBC2、MGBC3、PGBA2为醋酸钙不动杆菌(Acinetobacter calcoaceticus),菌株MGNB3、MGNB4为华夏氏肠杆菌(Enterobacter huaxiensis),菌株MGBD1为铜绿假单胞菌(Pseudomonas brassicacearum),菌株GND5为枯草芽孢杆菌(Bacillus subtilis),菌株GNA6为气泡微细菌(Microbacterium aerolatum),菌株GNB6为放射型根瘤菌(Rhizobium radiobacter)。     

人工林杉木压缩整形过程中的定形工艺

以蒸汽压力、时间及定形结束时蒸汽卸压速度为参数,对杉木压缩整形工艺的定形进行了试验.结果表明:1)整形过程中定形的蒸汽压力、定形时间对杉木定形后的体积压缩恢复率影响显著,而定形完成后的蒸汽卸压速度无显著影响;2)定形的蒸汽压力、定形时间的各个水平之间的定形效果差异极显著,理想的定形效果是在0.8 MPa的饱和蒸汽压下持续40 min.     

森林制氧固碳功能与效益计算的探讨

论述了森林制氧固碳功能，并以黑龙江省森工林区为例，求算出该林区森林每年的制氧和碳汇量与生态效益，指出提高森林生态功能的经营途径。     

Genetic Variation in Alfalfa, Sweet Clover and Fenugreek for the Activity of Symbiosis with Rhizobium meliloti

The aim of this work was to examine variation for activity of symbiosis with Rhizobium meliloti in alfalfa, sweet clover and fenugreek. Seed specimens were obtained from the collection of the All-Union Research Institute for Plant Breeding and Rhizobium strains from the All-Union Research Institute for Agricultural Microbiology, both in Leningrad. Sterile methods of vegetative culture were employed. Statistical analysis of data on inter- and intracultivar variation allow one to suppose that in alfalfa and sweet clover, nitrogenase activity and symbiotic efficiency (ability of plants to increase biomass after inoculation) are controlled by different groups of genes. The latter symbiotic property is more strictly controlled by host genotype than the former. Fenugreek appeared to be more variable in its capacity for symbiosis than alfalfa and sweet clover. Differences between genotyyes in symbiotic activity correlate with division into subspecies and are inherited in self-fertile progeny of fenugreek plants. Differences between R. meliloti strains for the efficiency of symbiosis with heterogceic natural fenugreek population are expressed to a lesser degree than with plants of more homogenic cultivar populations.     

Analysis of host genotype x rhizobial strain interaction in N2 fixation

Summary A method of analyzing host genotype x rhizobial strain interaction for N₂ fixation potential, based on the principle of structural relationship analysis, is proposed. When this interaction is significant, selecting genotypes for high N₂ fixation potential is incorrect, because the N₂ fixation efficiency is dependent on the rhizobial strain used. Under such circumstances, grouping genotypes based on average fixing ability (AFA), a linear response to the effectiveness of rhizobial strain, and specific fixing ability (SFA), deviation from the linear response in terms of the magnitude of the error variance, is useful before initiating a breeding program for enhanced N₂ fixation. Host genotype x strain interaction effect is partitioned into two components, and two parameters are derived which estimate AFA and SFA. N₂ fixation data from 3 mungbean genotypes and 6 rhizobial strains are used to illustrate this method.     

马尾松壮苗培育技术试验初报

通过控制播种时间、定苗时间和苗木保留密度可以有效地控制马尾松大田苗的抽梢，以达到培育壮苗、提高单位面积合格苗产量的目的。龙岩地区马尾松大田苗播种时间可选择在３月５—３０日之间，定苗时间可选择在７月中、下旬，苗木保留密度，苗圃土壤条件较好的可控制在２７０—３００株／ｍ２，苗圃土壤条件较差的可控制在３１５—３４０株／ｍ２左右。     

Litter production and nutrient cycling in coffee (Coffea arabica) or cacao (Theobroma cacao) plantations with shade trees

The relative importance of N fixation, organic material inputs and nutrient inputs in litterfall, as justifications for including shade trees in plantations of coffee or cacao, is discussed. According to existing data, N fixation by leguminous shade trees does not exceed 60 kg.N/ha/a. However, these trees contribute 5,000–10,000 kg. organic material/ha/a.Comparisons are made between the leguminous shade tree Erythrina poeppigiana and the non-leguminous timber tree Cordia alliodora. The former, when pruned 2 or 3 times/a., can return to the litter layer the same amount of nutrients that are applied to coffee plantations via inorganic fertilizers, even at the highest recommended rates for Costa Rica of 270 kg.N, 60 kg.P, 150 kg.K/ha/a. The annual nutrient return in this litterfall represents 90–100 percent of the nutrient store in above-ground biomass of E. poeppigiana, and hence the consequences of competition with the crop should not be a serious limitation. In the case of C. alliodora, which is not pruned, nutrient storage in the tree stems, especially of K, is a potential limiting factor to both crop and tree productivity.It is concluded that, in fertilized plantations of cacao and coffee, litter productivity is a more important shade tree characteristic than N fixation.An early version of this review was presented at the CATIE-IUFRO meeting Los Arboles de Uso Multiple en Sistemas Agroforestales, June 1985, Turrialba, Costa Rica.