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961.
桂西北秃杉人工林土壤肥力变化的研究   总被引:2,自引:0,他引:2       下载免费PDF全文
采用时空互换法,于广西南丹县山口林场选取不同林龄(9、14、20 a)的秃杉人工林作为研究对象,对其土壤物理性质、化学性质和生物化学性质(土壤酶活性)进行研究。结果表明:不同林分年龄土壤性质存在一定的差异,8、14、20 a秃杉人工林表层土壤(0 20 cm)土壤密度分别为0.978、0.914、0.890 g·cm-3,总孔隙度分别为63.10%、65.53 %、66.40%,土壤最大持水量分别为64.55%、71.70%、74.58%。随着林龄的增长,土壤各化学和生物化学指标的变化不尽相同,但林分年龄到20年生时,多数土壤养分和酶活性指标都有所升高,土壤肥力状况得到提高。  相似文献   
962.
在泰山发现自然生长的全株叶片沿叶脉银白或金黄色的柘树,经嫁接和组织培养的子代植株或再生芽均保持原有形态特性,其为柘树属一新品种(变种)。  相似文献   
963.
根据实地测定和前人研究成果,分析了施放生物定时水后土壤含水率、土壤水分蒸发、土壤水分渗漏及植物水分吸收关系,推导出造林植物需补充水量的公式,为生物定时水的造林应用提供理论依据。  相似文献   
964.
A total of 360 bark-to-bark-through-pith wood strips were sampled at breast height from 180 trees in 30 open-pollinated families from two rotation-aged genetic trials to study inheritance, age-age genetic correlation, and early selection efficiency for wood quality traits in radiata pine. Wood strips were evaluated by SilviScan® and annual pattern and genetic parameters for growth, wood density, microfibril angle (MFA), and stiffness (modulus of elasticity: MOE) for early to rotation ages were estimated. Annual ring growth was the largest between ages 2–5 years from pith, and decreased linearly to ages 9–10. Annual growth was similar and consistent at later ages. Wood density was the lowest near the pith, increased steadily to age 11–15 years, then was relatively stable after these ages. MFA was highest (35°) near the pith and reduced to about 10° at age 10–15 years. MFA was almost unchanged at later ages. MOE increased from about 2.5 GPa near the pith to about 20 GPa at ages 11–15 years. MOE was relatively unchanged at later ages. Wood density and MOE were inversely related to MFA. Heritability increased from zero near the pith and stabilised at ages 4 or 5 for all four growth and wood quality traits (DBH, density, MFA and MOE). Across age classes, heritability was the highest for area-weighted density and MFA, lowest for DBH, and intermediate for MOE. Age-age genetic correlations were high for the four traits studied. The genetic correlation reached 0.8 after age 7 for most traits. Early selection for density, MFA and MOE were very effective. Selection at age 7–8 has similar effectiveness as selection conducted at rotation age for MFA and MOE and at least 80% effective for wood density.  相似文献   
965.
本文以征用占用林地为例,列举出补偿应包括的主要内容,林地补偿与区域区位、补偿基数、补偿倍数等几个关键因素之间的关系等,提出了增加林地补偿合理性的一些思路。  相似文献   
966.
According to fixed-position data for 1985–2003 from nine runoff plots of Caijiachuan watershed which lies in Jixian County of Shanxi Province in Loess area, this paper studied the relationship between vegetation and runoff and sediment production in sloping lands in detail, which helps to provide scientific basis for vegetation re-construction and studies on environmental transformation of water and sediment in watersheds of Loess area. Although, many study results testify that forest vegetation has an important function in soil and water conservation and cutting runoff, the effect of vegetation on runoff and sediment transmission is complicated, and this needs to be studied in depth. The results of the paper showed the following. Firstly, the natural secondary forest performs better function of soil and water conservation than artificial Robinia pseudoacacia forest, and runoff and sediment produced in the former in individual rainfall were 65%–82% and 23%–92% of those produced in the latter. At the same time, better correlative relationship between runoff and sediment production and rainfall and rainfall intensity were testified by multiple regression, but the correlation decreased gradually with the increase of canopy density of forest. Secondly, the difference of runoff and sediment production in several land use types was very distinct, and the amount of runoff and sediment produced from Ostryopsis davidiana forest and natural secondary forest were the least, and runoff and sediment produced from in artificial Robinia pseudoacacia forest and Pinus tabulaeformis forest were 5-fold as much as those from O. davidiana forest. Besides, runoff and sediment produced in mixed planting of apple trees and crops were 16.14-fold and 2.96-fold than those of O. davidiana forest, respectively, but the amount decreased obviously after high-standard soil preparation in the case of the former. Thirdly, based on gray cognate analyses of factors affecting runoff and sediment production in sloping land, the factors of stand canopy density and herb and litter biomass were the most significant ones, whose gray incidence degree exceeded 0.6. Therefore, mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation re-construction of Loess area, which will help to increase coverage and litter thickness in order to cut down the runoff and sediment dramatically in sloping land. __________ Translated from Chinese Journal of Applied Ecology, 2005, 16(9): 1,613–1,617 [译自: 应用生态学报, 2005, 16(9): 1,613–1,617]  相似文献   
967.
国外国有林管理体制与产权变革及对我国的启示   总被引:11,自引:3,他引:11       下载免费PDF全文
简要分析了欧美市场经济国家国有林的管理体制及其改革动向,然后重点对原苏联东欧等经济转轨国家的国有林管理体制改革及其经验教训进行了分析。在此基础上,分析了其对我国国有林管理的启示与政策含义。  相似文献   
968.
尾叶桉、深山含笑、红锥苗接种内生菌根菌试验   总被引:4,自引:0,他引:4  
将从荔枝分离的AM菌根菌接种于尾叶桉组培苗,深山含笑和红锥种子苗,结果表明,AM菌根菌剂对供试的3种幼苗有明显的增效作用,对林业具有实际应用与开发价值。但其增效作用有差异,尾叶桉呈现逐渐增长的趋势,而深山含笑和红锥增长率达到最大后呈现缓慢下降的趋势。  相似文献   
969.
桉属树种与种源、家系比较试验   总被引:4,自引:2,他引:4       下载免费PDF全文
以9个桉属树种,其中8个种泊来自原产地,7个家系和7个杂种后代来自国内次生资源进行混合比较,5年生评价结果表明:树种、种源、家系呈极显著差异;尾叶桉及其两个种源、尾巨桉杂交种细叶桉的13544种源适合本试验区戒严和格短轮伐期经营,可获得适应性和生长指标平均值超过平均水平35%的选择效应。其中最优为14534号尾叶桉种源,5年生单株材积0.050.61m^3/株(89.03m^3/hm^2)。种子采  相似文献   
970.
通过1980~1987年秋季在大连老铁山、山东省长岛县大黑山岛及青岛浮山的观察研究,确认猛禽的迁徙与气候、天气有着密切的关系。猛禽迁徙通常选择在风力三级(14 km/h)以上西北风或南风的有利天气条件下顺风或侧顺风迁徒。这种大气环流形势在天气图上的反映是地面冷锋过境后当天或次日。冷锋过境前的天气特征是偏南风或西南风,气温升高,冷锋过境后风向转为西或西北风,同时气温下降,气压升高,风速加大。5~6级西北风(30~40 km/h)天气会出现猛禽大规模迁徙过境。故在猛禽的研究中,可根据这种天气变化模式进行猛禽迁徙的预报。  相似文献   
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