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61.
Zhen-Ming Ge Seppo Kellomäki Heli Peltola Xiao Zhou Kai-Yun Wang Hannu Väisänen 《Annals of Forest Science》2011,68(2):371-383
• Introduction
Based on previous studies, it is assumed that the growth of Norway spruce (Picea abies) in southern Finland (61°N) may decrease under the changing climate due to the increasing soil water deficit, without management. 相似文献62.
基于冠层光谱植被指数的冬小麦作物系数估算 总被引:2,自引:1,他引:1
目前针对局地气候条件下某一作物类型的作物系数及其年际变化已开展了较多分析,但适于区域尺度运用的作物系数估算方法的研究还比较缺乏,这是将FAO 56作物系数法成功应用于区域作物实际蒸散量估算的关键环节。该文基于2008-2009和2009-2010年度2个冬小麦生长季的大田试验数据,研究了作物系数(Kc)、基本作物系数(Kcb)与8种常用冠层光谱植被指数(VIs)的相关关系以及水分和氮素胁迫对其的影响,分析了基于VIs估算作物Kc、Kcb的可行性,并对其估算精度进行了验证。结果表明,高氮水平下Kcb较大而土壤蒸发系数(Ke)较小,低氮水平下Kcb较小而Ke较大,不同施氮水平下Kc无明显规律性差异。冬小麦Kc与VIs相关性较弱(决定系数R2=0.094~0.150,p<0.01,n=195),而Kcb与VIs则具有很强的相关性(决定系数R2=0.511~0.685, p<0.01,n=195);施氮水平不影响 Kcb-VIs 关系,而不足以使冠层光谱出现明显表征的水分胁迫可使 Kcb-VIs相关关系减弱。利用VIs估算的冬小麦实际生长条件下的Kcb值与FAO 56确定的Kcb值均具有很好的线性回归关系(R2=0.765~0.864,n=150),其中增强型植被指数(EVI)的估算精度最好。但在不足以使冠层光谱出现明显表征的水分胁迫条件下,利用该法可能会产生较大误差,还需要结合其他途径获取的水分胁迫信息来准确确定。 相似文献
63.
Heli K Hyyti?inen Sari H M?ls? Jouni T Junnila Outi M Laitinen-Vapaavuori Anna K Hielm-Bj?rkman 《Acta veterinaria Scandinavica》2013,55(1):29
Background
Various physiotherapeutic evaluation methods are used to assess the functionality of dogs with stifle problems. Neither validity nor sensitivity of these methods has been investigated. This study aimed to determine the most valid and sensitive physiotherapeutic evaluation methods for assessing functional capacity in hind limbs of dogs with stifle problems and to serve as a basis for developing an indexed test for these dogs. A group of 43 dogs with unilateral surgically treated cranial cruciate ligament deficiency and osteoarthritic findings was used to test different physiotherapeutic evaluation methods. Twenty-one healthy dogs served as the control group and were used to determine normal variation in static weight bearing and range of motion.The protocol consisted of 14 different evaluation methods: visual evaluation of lameness, visual evaluation of diagonal movement, visual evaluation of functional active range of motion and difference in thrust of hind limbs via functional tests (sit-to-move and lie-to-move), movement in stairs, evaluation of hind limb muscle atrophy, manual evaluation of hind limb static weight bearing, quantitative measurement of static weight bearing of hind limbs with bathroom scales, and passive range of motion of hind limb stifle (flexion and extension) and tarsal (flexion and extension) joints using a universal goniometer. The results were compared with those from an orthopaedic examination, force plate analysis, radiographic evaluation, and a conclusive assessment. Congruity of the methods was assessed with a combination of three statistical approaches (Fisher’s exact test and two differently calculated proportions of agreeing observations), and the components were ranked from best to worst. Sensitivities of all of the physiotherapeutic evaluation methods against each standard were calculated.Results
Evaluation of asymmetry in a sitting and lying position, assessment of muscle atrophy, manual and measured static weight bearing, and measurement of stifle passive range of motion were the most valid and sensitive physiotherapeutic evaluation methods.Conclusions
Ranking of the various physiotherapeutic evaluation methods was accomplished. Several of these methods can be considered valid and sensitive when examining the functionality of dogs with stifle problems. 相似文献64.
叶面喷施KH2PO4对密植幼龄骏枣光合特性日变化的影响 总被引:1,自引:1,他引:0
以新疆密植枣园幼龄骏枣为试验材料,采用单因素随机区组试验设计,开展了在开花坐果期叶面喷施不同浓度KH2PO4对叶片叶绿素含量及光合特性的影响研究。结果表明:叶面喷施钾肥能够显著提高骏枣叶片叶绿素a、叶绿素b和总叶绿素含量以及净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr),但不同的供钾水平并不改变骏枣各项光合气体交换参数的日变化规律。骏枣开花坐果期叶片Pn日变化曲线呈单峰型,无明显的“午休”现象,骏枣叶片净光合速率下降的主要原因在一天中表现不同,上午14:00之前主要是气孔因素,中午14:00以后主要是非气孔因素,而叶面喷施钾肥能够提高骏枣叶片的非气孔因素的作用,而降低气孔限制作用。Gs和Tr日变化均呈“M”型,两者的日变化趋势表现较好的协同性,适宜浓度的钾肥有助于提高骏枣叶片气孔导度Gs应对变化剧烈的气象条件的缓冲能力。同时,叶面施钾也促进了骏枣叶片Pn与气孔限制值(Ls)的相关性以及Pn与(潜在水分利用率)WUEi的相关性,降低了Pn与WUE(瞬时水分利用率)的相关性。本试验范围内,适宜KH2PO4叶面肥浓度为0.6%。 相似文献
65.
在盆栽试验条件下,以巴西香蕉幼苗为试材,设置7个水平土壤含水量处理,分别为100%~91%、90%~81%、80%~71%、70%~61%、60%~51%、50%~41%和40%~0,测定叶片相对含水量、组织含水量、自由水、束缚水含量、质膜透性和根系活力。研究结果表明,随着水分胁迫的加剧,叶片相对含水量、组织含水量、自由水含量和根系活力均随土壤相对含水量的下降而减少;而水分饱和亏缺、束缚水含量和质膜透性则随土壤相对含水量的下降而升高。综合不同处理下巴西香蕉幼苗水分状况、质膜透性和根系活力可知,香蕉幼苗生长最适宜的土壤水分含量是田间持水量的71%~80%。 相似文献
66.
城郊水库消涨带既要具有水源保护功能又要满足生态景观要求。在深圳市水源保护林建设专题研究的基础上,结合消涨带植物筛选试验成果,初步提出库区消涨带植被重建的技术体系。在正常水位线往下3 m内栽植乔木和草被,正常水位线往下3-6 m内栽植草被,同时结合生物排水沟、生态袋反坡梯地及反坡鱼鳞坑等辅助工程措施,可为水库消涨带生态重建提供途径。 相似文献
67.
Many forest-dwelling species are dependent on deadwood. Sources of deadwood include competition- and senescence-related mortality of trees, and various damages. This study described a methodology for predicting the effect of wind damage on the amount of deadwood and suitability of the forest for saproxylic species. The methodology was used in a forested boreal landscape of 360 ha to analyze the effects of wind damage on the habitat quality for 27 groups of saproxylic species differing in their requirements for the species, size and decay stage of deadwood objects. A reference plan maximized net present value (MaxNPV) while others either minimized or maximized height differences between adjacent stands. Maximization of height differences resulted in high amount of wind damage and deadwood while minimizing height differences minimized wind damage and the amount of damage-related deadwood. The fourth plan maximized the average habitat suitability index (HSI) of the 27 groups of saproxylic species. The plans were compiled with and without even-flow harvesting constraints for three 10-year periods. Maximization of height differences between adjacent stands resulted in higher HSI values than obtained in the MaxNPV plan or in the plan than minimized height differences between adjacent stands. The average HSI of shade-demanding species correlated negatively with the amount of harvested timber. No strong correlations were found for light-demanding and indifferent species. 相似文献
68.
Kari HELIVAARA 《中国林学(英文版)》2009,11(1):55-60
Taking the communities of the sample sites in Aershan of Inner Mongolia as an investigation object, the indices affecting plant diversity were studied. The investigation was carried out in three different forest types (natural forests, plantations and regenerated forests after fire). Results show that 95 plant species belonging to 19 families and 50 genera were identified in total. Of these species, nine were arbors, six were shrubs and the other 80 were herbs. We found some differences in the dominant species of different layers in three forest types. Natural forests had the largest importance value for the total number of species, followed by plantations and regenerated forests after fire. Plantations and natural forests had a similar change in richness indices. The largest value of richness indices was obtained in natural forests, while the lowest value was in regenerated forests after fire. Three diversity indices (Simpson’s, Shannon-Wiener and Pielou’s indices) indicate a similar trend in all sample plots. With an increase in elevation, values of diversity indices first increased and then decreased. In different forest types, similarity between natural forests was largest, while similarity between the regenerated forests and plantations was lowest. 相似文献
69.
Ane Zubizarreta Gerendiain Heli Peltola Pertti Pulkkinen Seppo Kellomäki 《Annals of Forest Science》2009,66(8):806-806
70.
本试验测定了两个马铃薯品种在4 ℃和10 ℃低温贮藏条件下块茎的呼吸强度和蔗糖、还原糖的含量。 N D860 2 品种在4 ℃和10 ℃条件下, 还原糖含量变化差异不大, 而 Norchip 品种在4 ℃下还原糖含量远远高于10 ℃的处理。两个品种块茎中蔗糖含量甚微。呼吸强度与还原糖含量的变化的相关性不明显。结果表明, 两个品种在低温条件下糖代谢机理不同。 相似文献