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101.
海南省两种人工林林下物种多样性与土壤水分物理性质的关系 总被引:3,自引:0,他引:3
通过测定和比较分析海南桉树人工林和橡胶人工林的林下植物多样性、土壤水分物理特性以及林下物种多样性与土壤水分物理性质的关系,结果表明:(1)桉树林下植物种类共有22种,分属14科20属,橡胶林下植物种类共有25种,分属15科22属。(2)两种森林的土壤容重总体表现为表层小于底层,表土层中桉树林的土壤容重均大于橡胶林,而中下层的土壤容重是前者小于后者;土壤总孔隙度均随深度增加呈减小趋势,在表土层中,橡胶林土壤总孔隙度大于桉树人工林,而在底土层中两种林型接近;橡胶林的毛管孔隙度随土层增加呈递减趋势,桉树林是先减小后增加;在表土层,两种林型的土壤非毛管孔隙度表现为橡胶林大于桉树林,在底土层两种林型基本一致。两种森林的土壤毛管持水量、最大持水量、土壤田间持水量、土壤排水能力均为:橡胶林大于桉树林。(3)与橡胶林相比,桉树林植物多样性与土壤物理特性相关性较小,而负相关程度较高;土壤毛管孔隙度、排水能力对桉树林下物种多样性起促进作用,而非毛管孔隙度、田间持水量起抑制作用;橡胶林物种多样性与毛管孔隙度及非毛管孔隙度呈正相关,与最大持水量、田间持水量及排水能力呈负相关。因此,橡胶林下物种多样性、土壤水分物理特性均优于桉树林,控制两种人工林林下物种多样性大小的土壤水分因子是不同的。 相似文献
102.
用不同浓度的新型植物生长调节剂p3s处理橡胶苗,研究其对橡胶苗生长发育的影响以及对抗性相关酶的活性调节,并通过接菌试验检验p3s对橡胶苗抗病性的作用。结果显示,p3s显著优化了株高、茎粗、叶片面积、叶蓬距等生长指标,用6.0 mg/L p3s喷药,效果最佳。对药剂处理过的叶片过氧化物酶(POD)、多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)活性进行测定,与对照相比,4.5 mg/L p3s处理的POD活性显著提高;6.0 mg/L p3s处理的PPO和PAL活性显著提高;最优浓度6.0 mg/L p3s处理后,叶片POD、PPO和PAL活性能在一定时间内保持较高水平;且6.0 mg/L p3s处理显著提高了橡胶苗对炭疽病的抗病能力。表明p3s能促进橡胶苗的生长发育,并有效提高其抗逆性和抗病性,且药效持续时间长。 相似文献
103.
在84m2区域内对橡胶园土壤按0.5 m×1 m网格进行取样(n=168),对5种土壤肥力指标进行地统计学分析.结果表明:全氮、有效磷、速效钾、有机质和pH值的半方差函数均可用指数模型描述,其各自变程分别为1.44、1.65、3.36、1.20和1.74m,均表现出强空间自相关关系.从土壤肥力指标的空间分布特征来看,全氮、有效磷、有机质呈现出明显的“肥岛”效应,其中全氮“肥岛”面积最大,影响距离最远;有效磷的“肥岛”面积最小,与周围浓度成倍数递减,成同心圆结构;有机质的空间分布特征介于二者之间;速效钾斑块面积分布比较均匀,与土壤母质类型有关. 相似文献
104.
海南热带砖红壤有机组分对植胶与橡胶连作的响应 总被引:1,自引:1,他引:0
以海南天然次生热带雨林、第1代胶园和第2代胶园林下花岗岩母质发育的砖红壤为研究对象,研究随着天然次生林开垦为第1代胶园,并更新为第2代胶园以后,土壤有机组分的变化规律以及在土层的迁移。结果表明:在0~20 cm土层,天然次生林土壤有机碳及各有机组分碳含量均显著高于第1代胶园和第2代胶园,第1代胶园土壤有机碳、颗粒有机碳、胡敏酸和黑炭碳含量显著高于第2代胶园土壤,第2代胶园土壤富啡酸和土壤球囊霉素相关蛋白碳含量呈下降趋势,但与第1代胶园土壤差异不显著;在20~40 cm土层,天然次生林和第1代胶园土壤有机碳及各有机组分碳含量差异均不显著,天然次生林土壤有机碳、颗粒有机碳、胡敏酸和黑炭碳含量显著高于第2代胶园土壤,第1代胶园土壤颗粒有机碳和胡敏酸碳含量显著高于第2代胶园土壤,其他各有机组分碳含量差异不显著。随着植胶和橡胶连作,土壤有机质和各有机组分含量大幅度降低,但不同有机组分含量降低幅度不同。同时植胶和橡胶连作会影响各有机组分在表层和亚表层的分配,天然次生林土壤有明显的表聚性,胶园土壤有机质和各有机组分含量在表层和亚表层差异不显著。 相似文献
105.
C.R. Benedict Rachel Goss M.A. Foster Paul J. Greer 《Industrial Crops and Products》2009,30(3):403-406
In this paper we have examined rubber particle formation in cortical parenchyma cells of guayule (Parthenium argentatum Gray) plants exposed to the low temperature of the fall and winter of the Chihuahuan Desert that stimulates rubber formation.Plants were transplanted to field plots in May in Ft. Stockton, TX. In September most of the cortical parenchyma in cross-sections 3 cm from the stem tips and from the base of the stems were mature, containing a central vacuole, tonoplast and a parietal cytosol with chloroplasts, mitochondria, peroxisomes and a few rubber particles. In 8-month-old plants examined in January many of the cortical parenchyma cells 3 cm from the stem tip were immature and completely filled with cytosol containing a high population of rubber particles. At this stage of development there was a thickened secondary cell wall but no central vacuole, tonoplast or parietal cytosol and all the rubber particles were formed in the central cytosol. In the cortical parenchyma in early stages of central vacuole development, by the coalescing of microvacuoles, the rubber particles were located in the developing central vacuole and in the cytosol being appressed toward the cell wall. In 8-month-old plants in January, the cortical parenchyma at the base of the stems was more mature than cells near the stem tips. These cells showed a later stage of development of a central vacuole from microvacuole fusing and contained a high population of mixed sizes of rubber particles and a thin layer of parietal cytosol containing chloroplasts, mitochondria and rubber particles with a partly developed tonoplast. There was clear evidence of the fusion of small rubber particles with other rubber particles that may represent a mechanism for the growth of rubber particles. 相似文献
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109.
The Upland Settlement Project of Bangladesh as a Means of Reducing Land Degradation and Improving Rural Livelihoods 总被引:1,自引:1,他引:0
Because of illegal logging, increased population pressure and intensified shifting cultivation, forest coverage of the Chittagong
Hill Tracts (CHT) has decreased drastically resulting in land degradation. Many development projects have been implemented
to combat forest loss and land degradation and also to improve the livelihoods of the hill people. This paper reports an empirical
study of the Upland Settlement Project (USP) of Bangladesh which was undertaken to prevent land degradation and enhance the
standard of living of the people. Planters were found to have given up shifting cultivation and adopted soil conserving agroforestry
practices, and forest coverage has been increased in the project village. Interacting with project staff members, government
officials and NGOs assisted planters in diversifying livelihood strategies thereby reducing dependency on project resources.
Rich planters, utilizing their own capacity, expanded their income sources successfully. Poor planters still remain wage labourers
because they do not have sufficient finance and networks to invest in productive ventures. Planters’ participation in project
activities and the information flow between them and project staff were found to be minimal. Suggestions are made for the
continuity of project functions, which involve greater participation of planters in rubber management functions, improved
information flow, resolution of land tenure and greater equality in distribution of rubber revenue.
相似文献
Tapan Kumar NathEmail: |
110.