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171.
Elizabeth Álvarez Lederson Gañán Alberto Rojas-Triviño Juan F. Mejía Germán A. Llano Alonso González 《European journal of plant pathology / European Foundation for Plant Pathology》2014,139(2):319-332
Anthracnose, caused by Colletotrichum species is a highly limiting disease for the production of the tropical fruit tree crop, soursop (Annona muricata L.). In this study, 83 single-spore isolates of Colletotrichum were obtained from diseased soursoup tissues and subjected to a species complex-specific PCR assay. The isolates were identified as C. gloeosporioides sensu lato (n?=?60), C. boninense s. lat. (n?=?22), or C. acutatum s. lat. (n?=?1). A subset of 21 selected isolates was identified to species level by means of a multi-locus phylogenetic analysis using sequences from the ITS region and partial sequences of the actin, β-tubulin-2, glyceraldehyde-3-phosphate dehydrogenase, and chitin synthase-1 genes. The multi-locus phylogenetic analysis resolved C. theobromicola, C. tropicale, C. siamense, and C. gloeosporioides sensu stricto in the C. gloeosporioides complex; C. karstii and one undetermined species in the C. boninense complex; as well as one undetermined species in the C. acutatum complex. Significant differences in anthracnose severity were observed between Colletotrichum species when tested for pathogenicity on attached twigs of soursop cv. Elita. Colletotrichum theobromicola and C. tropicale were associated with high and intermediate virulence, respectively, whereas the remaining species were associated with low virulence. 相似文献
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主要研究了西藏野生油菜,特别是野生白菜型油菜和野生芥菜型油菜单株粒重的种质资源。通过对采集来的西藏野生白菜型油菜和野生芥菜型油菜株粒重种质资源的研究与鉴定发现:在西藏野生油菜种质资源中,野生白菜型油菜存在着株粒重低级到株粒重高级的2个等级;而在西藏野生芥菜型油菜种质资源中,存在着株粒重低级到株粒重高级的3个等级,其中野生芥菜型油菜种质资源株粒重较高的材料所占的比例明显强于野生白菜型油菜。并且通过大田鉴定从中分离出一些优质的西藏野生油菜种质资源,如:野白13(9 g/株)、野芥6(13.4 g/株)、野芥24(11.6 g/株)、野芥25(17.7 g/株)、野芥29(11.0 g/株)、特别是野芥15(27.1 g/株)和野芥26(20.4 g/株)等单株粒重高的优良种质资源。 相似文献
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藏西北高寒牧区气候特征及草地退化原因分析 总被引:4,自引:1,他引:3
本文利用藏西北高寒牧区9个气象站1971~2005年共35年的观测资料以及现代气候统计方法,分析了该区域与牧草长势相关的温度、降水、蒸发量等气象因子气候变化特征。分析表明,近35年来,藏西北高寒牧区平均温度、降水量的变化趋势为逐年增加,蒸发量逐年减小;各季节的变化与年变化趋势大致相同;藏西北高寒牧区两大区域,阿里地区的北部和那曲地区的气候特征存在明显差异;从牧草生长最重要的热量和水分条件来看,阿里牧区的气候变化特征朝着干热方向发展,对牧草的生长有不利影响,而那曲牧区气候变化特征为暖湿型,有利于牧草生长。然而,通过对整个藏西北高寒牧区牧草的研究表明,无论是阿里地区还是那曲地区,牧草都呈现出了退化趋势,导致草地退化的主要因素,除自然天气气候因素外,人类活动不可忽视。 相似文献
176.
Noubar J Bostanian John M Hardman Howard A Thistlewood Gaétan Racette 《Pest management science》2010,66(11):1263-1267
BACKGROUND: Neoseiulus fallacis (Garman) is a key predator of tetranychid mites in integrated pest management (IPM) programs across Canada. This study identified compounds that would be recommended for tier‐II field evaluations in an IPM program. RESULTS: The overall egg mortality caused by the six insecticides was negligible as it extended from 0 to 12.1%. Imidacloprid was classified as toxic to adults. The label rate was 7.73‐fold the LC50. Thiamethoxam was classified as moderately toxic to adults, and its label rate was 2.87‐fold the LC50. Acetamiprid and spinosad were classified as marginally toxic, and their label rates were respectively 0.99‐ and 0.45‐fold the LC50 for adults. Thiacloprid and methoxyfenozide were virtually innocuous to adults. CONCLUSION: Methoxyfenozide was totally harmless to all stages of N. fallacis, and it would be included in IPM programs immediately. Acetamiprid, spinosad and thiacloprid had varying degrees of mild toxicity to at least one growth stage of the predator. Therefore, they were recommended for tier‐II field testing according to their label claims. Imidacloprid and thiamethoxam were toxic to moderately toxic to adults and had significant adverse effects on fecundity. Therefore, they would be field evaluated only if alternatives were unavailable. Copyright 2010 Crown in the right of Canada. Published by JohnWiley & Sons, Ltd 相似文献
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藏东南生态旅游资源的分类与旅游业可持续发展战略探讨 总被引:2,自引:0,他引:2
在藏东南生态旅游资源的实地调查的基础上,采用创新型生态旅游资源分类系统,对藏东南生态旅游资源进行了分类和定性评价。藏东南生态旅游资源丰度大,品位高,民风民俗优势突出,生态旅游资源组合度好。在已查明的419个生态旅游资源单体中,藏东南生态旅游资源类型囊括了生态旅游资源分类系统3大类、8类的27小类,具有多样性、垄断性、宗教性、民族性、原始性特征。丰富的生态旅游资源吸引着众多的国内外游客,蕴藏着极大的开发利用价值,为藏东南生态旅游业可持续发展提供了坚实的物质基础。 相似文献
180.
Roques JA Abbink W Chereau G Fourneyron A Spanings T Burggraaf D van de Bos R van de Vis H Flik G 《Fish physiology and biochemistry》2012,38(4):1019-1028
Consumer awareness of the need to improve fish welfare is increasing. Electrostunning is a clean and potentially efficient procedure more and more used to provoke loss of consciousness prior to killing or slaughtering (reviewed by Van de Vis et al. in Aquac Res 34:211-220, 2003). Little is known how (powerful) electrical stimuli, which do not stun immediately, are perceived by fish. We investigated responses of hand-held Mozambique tilapia (Oreochromis mossambicus) to a standardized electric shock applied to the tailfin. The handling with the resulting unavoidable acute stress response was carefully controlled for. Fish responses were analyzed up to 24 h following the shock. Electric shock resulted in slightly higher levels in plasma cortisol, lactate, ionic levels, and osmolality, than handling alone. Plasma glucose had significantly increased 6 h after shock compared to handling, indicative of enhanced adrenergic activity. Mucus release from the gills, branchial Na?/K? ATPase activity, and chloride cell migration and proliferation, parameters that will change with strong adrenergic activation, were not affected. Decreased swimming activity and delay in resumption of chafing behavior indicated a stronger and differential response toward the electric shock. Responses to handling lasted shorter compared to those to an electric shock. The differential and stronger responses to the electric shock suggest that fish perceived the shock potentially as painful. 相似文献