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81.
Soil salinity is becoming an increasingly serious constraint to plant growth in many parts of the world;this is particularly common in semi-arid and arid zones. This study was conducted to evaluate the... 相似文献
82.
《Southern Forests》2013,75(3-4):175-180
Ganoderma root rot is the most serious disease affecting commercially planted Acacia mangium in plantations in Indonesia. Numerous Ganoderma spp. have been recorded from diseased trees of this species and to a lesser extent Eucalyptus, causing confusion regarding the primary cause of the disease. In this study, a large collection of Ganoderma isolates were obtained from the roots of A. mangium showing early signs of root rot in disease centres in South Sumatra plantations. Isolates were also collected from Eucalyptus roots at Lake Toba in North Sumatra showing similar symptoms as well as from sporocarps connected to these samples. Phylogenetic analyses showed that a single Ganoderma sp., identified as G. philippii, is the major causal agent of Ganoderma root rot on A. mangium. Results from this study also showed that the isolates obtained for Eucalyptus trees in North Sumatra belong to G. philippii. Isolates from roots and connected fruiting bodies together with the morphology of the fruiting structures confirmed this identification. Symptoms associated with this pathogen are obvious and it should not be confused with other diseases. Other Ganoderma spp. found in disease centres are considered to be of minor importance and management strategies for root rot should be focused on G. philippii. 相似文献
83.
利用MaxEnt模型评估黑木相思在中国引种的潜在适生区,探讨影响其适生区分布的主要生态因子,并对适生区范围和类型进行划分,旨在为该树种在中国的引种区划提供依据。采用ENMeval数据包优化的MaxEnt模型,基于14个环境变量和159条黑木相思分布点,以我国95°-125°E、17°-38°N区域为模型投射空间范围,评估黑木相思的潜在适生地理分布;通过Spearman相关分析、方差膨胀因子(VIF)分析和刀切法检验,筛选出制约其潜在分布的主导环境因子。经ENMeval优化,当特征组合FC=QHP,调控倍频RM=6时,AUC值为0.965,模型准确度极高。刀切法检验表明:最干月降雨量(40.1%)、月平均昼夜温差(26.9%)、年降水量(15.6%)、年均温(6.6%)、最冷月最低温(3.2%)和表层土壤酸碱度(2.8%)是影响黑木相思地理分布的重要生态因子,累计贡献率达95.2%。结果表明,黑木相思在中国适生区分为高(55.835 4×104 km2)、中... 相似文献
84.
不同剂量稀土对金雨金合欢幼苗生长的影响 总被引:2,自引:0,他引:2
为明确稀土对金雨金合欢幼苗生长的影响,采用8种不同剂量的稀土对金雨金合幼苗进行根施。结果表明:1)金雨金合欢幼苗施入稀土后,7~10d起幼苗形态出现不同的变化,比对照出现相同反应提早5~6d;2)90d的各项测定生长指标分析表明,每株施入0.05~1.00g剂量稀土,对幼苗生长具有较好的促进作用,其幼苗高、地径净增长,全苗鲜、干重量,叶片总面积,根系总长度、根系表面积和根尖数量总体上呈有规律的增长趋势,均显著高于对照(P<0.05),以施入剂量0.25g·株-1处理表现最好,其苗木出圃率达到100%,与对照相比,苗高、地径净增长了204.0%和102.0%,叶片总面积、根系总长度、根系表面积和根尖数量分别增长了976%、339%、405%和187%,全苗鲜、干重量,提高了61.5%和133.3%;3)当施入剂量超过2.00g·株-1时,苗木生长开始受抑,出现"毒害"反应,其各项生长指标下降,部分苗木死亡,并随剂量增大,生长受抑程度加剧,生长指标下降速度增大,幼苗死亡数量增多。表明低浓度的稀土溶液根施,对金雨金合欢幼苗生长具有促进作用,高浓度则抑制了其生长,甚至会导致死亡。 相似文献
85.
为丰富桂东地区速生树种多样性以及为生态敏感地区桉树改造提供新的树种,2017年5月在桂东地区试种黑木相思17号无性系20hm^2,分别在造林后第8个月和14个月调查试验林不同海拔、坡向、坡位的林分生长情况,试验结果表明:黑木相思17号无性系在桂东地区造林成活率85%以上,造林后第8个月成活率、地径和树高分别为92%,3.1cm和2.3m,造林第14个月地径、胸径和树高分别为7.4cm,5.8cm和5.0m;黑木相思造林后8-14个月,上坡生长表现优于下坡,海拔200m生长表现优于海拔320m。说明黑木相思17号无性系适合在桂东地区生长,避开谷底和山脚等光照不足地块、及时抚育是黑木相思在桂东地区造林成功的关键。 相似文献
86.
Motubatse MR Ng'ambi JW Norris D Malatje MM 《Tropical animal health and production》2008,40(3):229-238
In a first of two experiments, twenty yearling male Pedi goats weighing 21.3 ± 0.5 kg live weight were used in a 37-day study
in a 2 (levels of PEG 4000) × 2 (levels of Acacia) Factorial arrangement in a Completely Randomised Design to determine the
effect of the level of Acacia nilotica leaf meal supplementation plus 23 g polyethylene glycol 4000 on diet intake and digestibility, and growth rate of Pedi goats
fed ad libitum Buffalo grass hay. Acacia nilotica leaf meal contained high amounts of total phenolics (2.04 % DM) and low amounts of condensed tannins; both extracted (0.37
% DM) and unextracted (1.83 % DM). Supplementation with PEG 4000 increased (P < 0.05) crude protein intake as the level of
Acacia nilotica leaf meal increased from 80 to 120 g. Similarly, treatment with PEG 4000 improved (P < 0.05) DM, OM and CP digestibilities
when compared to 80 g Acacia nilotica leaf meal. Supplementation with PEG 4000 resulted in an increase (P < 0.05) in blood urea concentrations. Polyethylene glycol
4000 has the potential to improve the feeding value of A. nilotica leaf meal and can, therefore, be used in the feeding systems for ruminant animals. The second experiment determined the effect
of A. nilotica leaf meal supplementation on in vitro digestibility of the diets similar to the actual ratios of the first experiment. Level of A. nilotica leaf meal supplementation plus 23 g PEG 4000 supplementation improved (P < 0.05) in vitro DM, OM and CP digestibilities where 120 g A. nilotica leaf meal was supplemented. Similarly, 23 g PEG 4000 supplementation also improved (P < 0.05) in vitro CP digestibility where 80 g A. nilotica leaf meal was supplemented. In vivo DM and OM digestibilities were best predicted from in vitro DM and OM digestibilities while in vivo CP was explained by in vitro OM and CP digestibilities. It is, therefore, concluded that in vitro DM and OM digestibilities have good capacity to predict in vivo DM and OM digestibilities while OM and CP digestibilities have good capacity to predict in vivo CP digestibility. 相似文献
87.
桉树与厚荚相思混交林的生物量及对土壤影响研究 总被引:11,自引:0,他引:11
对雷州林业局营造桉树与厚荚相思混交林进行生物量测定及对土壤影响的分析结果表明:尾叶桉与厚荚相思混交林6年生地上部分群体生物量比尾叶桉纯林多36.6%以上,单株叶量,细根行间混交的尾叶桉分别比纯林的尾叶桉多38.4%,82.8%,带状混交的尾叶桉比纯林的尾叶桉分别多19.5%,4.7%,林分叶量带状混交林比纯林大4.9倍。4年生时混交林凋落物干重比纯林多31%以上。混交林0-39cm土层有机质,全氮 相似文献
88.
Ceratocystis albofundus is a recently described pathogen infectingAcacia mearnsii in South Africa, and it causes a disease known as Ceratocystis wilt. Symptoms of the disease include die-back, gummosis and
wilting of infected trees. In order to select trees tolerant to this fungus, susceptibility tests were conducted on trees
representing fourteen families ofA. mearnsii. A virulent isolate ofC. albofundus was selected and inoculated into the stems of twelve-month-old plants in a plantation. Lesion lengths, in the bark, and disease
development were assessed after 6 weeks. All fourteen families ofA. mearnsii were susceptible to infection byC. albofundus. Considerable variation was, however, noticed between individual trees within the same family and the incorporation of disease
tolerant trees into breeding programmes is proposed. 相似文献
89.
黑荆树巨尾桉混交造林与效益分析 总被引:3,自引:0,他引:3
设计了以黑荆树与巨尾桉混交的3个模式、黑荆树纯林、巨尾桉纯林共5个处理进行试验。经过一个轮伐期6a的观测研究,结果表明以黑荆树4巨尾桉1的混交比例作株间混交的模式最为理想,6年生林分总蓄积量达72.1m3·hm-2,其中巨尾桉46.1m3·hm-2,黑荆树26.0m3·hm-2,投入产出比为1∶3.4。 相似文献
90.