全文获取类型
收费全文 | 86篇 |
免费 | 7篇 |
专业分类
林业 | 17篇 |
农学 | 7篇 |
10篇 | |
综合类 | 12篇 |
农作物 | 3篇 |
水产渔业 | 7篇 |
畜牧兽医 | 37篇 |
出版年
2022年 | 1篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 3篇 |
2012年 | 5篇 |
2011年 | 2篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 4篇 |
2007年 | 4篇 |
2006年 | 1篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1970年 | 2篇 |
1968年 | 5篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1965年 | 1篇 |
1955年 | 1篇 |
1931年 | 1篇 |
1929年 | 1篇 |
1926年 | 1篇 |
排序方式: 共有93条查询结果,搜索用时 15 毫秒
1.
Nagel TJ 《Science (New York, N.Y.)》1978,201(4360):985-993
2.
C Bogni M Segura J Giraudo A Giraudo A Calzolari R Nagel 《Canadian journal of veterinary research》1998,62(4):293-298
An avirulent mutant, designated RC122, was derived from Staphylococcus aureus bovine mastitis strain RC108 after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis. Mutant RC122, which was isolated on the basis of reduced colony size, showed diminished virulence in mice (LD50 of RC122: 3.1 x 10(10) cfu vs LD50 of RC108: 2.3 x 10(7) cfu). Mutant RC122 grew more slowly than its parental strain and showed decreased production of several exoproteins, such as alpha- and beta-hemolysin, DNAse and coagulase. The production of its capsule was induced only under in vivo growth conditions. Clearance studies performed in the mouse kidney revealed that the kinetics of disappearance of the mutant was similar to that of its parental strain. Protection experiments carried out by intraperitoneal administration in mice showed that mutant RC122 conferred a good degree of protection from challenge with homologous and heterologous strains. 相似文献
3.
4.
5.
In the bottlenose dolphin Tursiops truncatus, a massive retial complex is interposed between the systemic and cerebral circulations at the cervicothoracic level. Pressure measurements in the retial efferent arteries supplying the brain revealed relatively nonpulsatile pressure profiles. These measurements in the anesthetized dolphin demonstrate the pressure-damping effect of the retia mirabile. 相似文献
6.
7.
8.
Gap disturbances and regeneration patterns in a Bosnian old-growth forest: a multispectral remote sensing and ground-based approach 总被引:1,自引:0,他引:1
Matteo Garbarino Enrico Borgogno Mondino Emanuele Lingua Thomas A. Nagel Vojislav Duki? Zoran Govedar Renzo Motta 《Annals of Forest Science》2012,69(5):617-625
Objectives
We examined canopy gap structure and regeneration patterns at the landscape scale using a combination of remote sensing and field-based surveys.Methods
The study was carried out in the forest reserve of Lom, an old-growth Fagus-Abies-Picea forest located within the Dinaric Alps in the north-western part of Bosnia and Herzegovina. A high-resolution (1-m panchromatic and 4-m multispectral) Kompsat-2 satellite image was orthorectified and classified through an unsupervised pixel-based classification using an artificial neural network method.Results
This approach allowed the identification of 650 canopy gaps, ranging in size from 32 to 1,776?m2. Only 20 intermediate to large gaps (>250?m2) were identified, and they were mainly present near the perimeter of the reserve. The origin of these large openings was associated with past human-caused disturbances or topographic conditions. The species composition of regeneration within large, human-caused gaps differed markedly from small gaps and non-gap sites in the core area of the reserve. Shade-intolerant species dominated the seedling and sapling layers in large openings. The landscape approach employed in this study confirmed the hypothesis that small gaps predominate at Lom, especially within the core area of the reserve. 相似文献9.
Kurt Nagel M. Abdul Mottaleb Jonathan Wistrom Michael Bellamy 《Communications in Soil Science and Plant Analysis》2019,50(8):987-1002
Biochar, a carbon-rich by-product of biomass pyrolysis, is widely recognized as a potential ingredient for soil amendment, fertility, and carbon sequestration owing to its favorable physicochemical properties. The objective of this study was to investigate the chemical and physical properties of biochars produced through pyrolysis at 450°C from agricultural residues available in Northwest Missouri, namely hardwood (HW), corn stover (CR), miscanthus (MS), and horse manure (HM). These properties were assessed through the analysis of pyrolysis yield, pH, volatile matter, fixed carbon, ash and carbon (C), hydrogen (H), sulfur (S), nitrogen (N) contents, trace metal concentrations, surface morphology, surface functional groups, bulk density, and water holding capacity. The biochars derived from HW, MS and CR materials showed high volatile-matter (33–42%), high fixed carbon contents (42–47%), very low ash contents (6–15%), and low bulk density (0.14–0.28 g cm?3) as compared to that of HM. A wide range of trace elements was observed in biochar samples with significant differences in concentrations. In addition, CR, HW and MS biochars displayed a disordered graphitic-like structure with well-developed pores and surface areas of 23, 70 and 90 m2/g respectively, and high water-holding capacity up to 750%, indicating their potential application as a soil amendment. 相似文献
10.
Sirisakulwat S Nagel A Sruamsiri P Carle R Neidhart S 《Journal of agricultural and food chemistry》2008,56(22):10727-10738
Pectins, recovered from the peels of four mango ( Mangifera indica L.) cultivars by mimicking industrial techniques, were evaluated in terms of yield, composition, macromolecular properties, and technofunctional quality. Freeze-dried peels of mature-green fruits, after major mesocarp softening, and at full ripeness were extracted using hot acid. The pectins were precipitated in propan-2-ol and their crude yields quantified as alcohol-insoluble substance. Like apple pomace, the dried peels provided hardly acetylated (DAc < 6.3%) rapid-set to ultrarapid-set high-methoxyl pectins at starch-adjusted yields of 11-21 g/100 g. However, despite similar high molecular weight fractions and galacturonic acid/rhamnose ratios, their average molecular weight was markedly reduced by a characteristic, almost monodisperse fraction of 16000-19000. Expanded galactans, indicated by galactose/rhamnose ratios of 15-24 mol/mol, probably represented arabinogalactan side-chain fragments withstanding hot-acid extraction at pH 1.5 and 2.0, as implied by arabinose/galactose ratios of 8-15 and 33-56 mol/100 mol, respectively. Limited galacturonic acid contents made the mango peel pectins less valuable than commercial apple pectins with regard to gelling capacity and thickening properties. Whereas starch and matrix glycan fragments almost completely degraded during ripening, depolymerization of pectins and galactans was insignificant. Technofunctional properties, modulated by extraction at different pH values, were ascribed to structural differences influencing macromolecular entanglements. 相似文献