全文获取类型
收费全文 | 163篇 |
免费 | 14篇 |
专业分类
林业 | 16篇 |
农学 | 10篇 |
49篇 | |
综合类 | 21篇 |
农作物 | 8篇 |
水产渔业 | 15篇 |
畜牧兽医 | 46篇 |
园艺 | 7篇 |
植物保护 | 5篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 7篇 |
2020年 | 3篇 |
2019年 | 11篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 5篇 |
2013年 | 13篇 |
2012年 | 10篇 |
2011年 | 19篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 17篇 |
2007年 | 12篇 |
2006年 | 3篇 |
2005年 | 6篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1992年 | 1篇 |
1986年 | 1篇 |
1981年 | 2篇 |
排序方式: 共有177条查询结果,搜索用时 15 毫秒
91.
Although curvature of biological surfaces has been considered from mathematical and biophysical perspectives, its molecular and developmental basis is unclear. We have studied the cin mutant of Antirrhinum, which has crinkly rather than flat leaves. Leaves of cin display excess growth in marginal regions, resulting in a gradual introduction of negative curvature during development. This reflects a change in the shape and the progression of a cell-cycle arrest front moving from the leaf tip toward the base. CIN encodes a TCP protein and is expressed downstream of the arrest front. We propose that CIN promotes zero curvature (flatness) by making cells more sensitive to an arrest signal, particularly in marginal regions. 相似文献
92.
Shrub biomass estimation in the semiarid Chaco forest: a contribution to the quantification of an underrated carbon stock 总被引:1,自引:0,他引:1
Georgina Conti Lucas Enrico Fernando Casanoves Sandra Díaz 《Annals of Forest Science》2013,70(5):515-524
Context
The quantification of biomass of woody plants is at the basis of calculations of forest biomass and carbon stocks. Although there are well-developed allometric models for trees, they do not apply well to shrubs, and shrub-specific allometric models are scarce. There is therefore a need for a standardized methodology to quantify biomass and carbon stocks in open forests and woodlands.Aims
To develop species-specific biomass estimation models for common shrubs, as well as a multispecies shrub model, for the subtropical semiarid Chaco forest of central Argentina.Methods
Eight shrub species (Acacia aroma, Acacia gilliesii, Aloysia gratissima, Capparis atamisquea, Celtis ehrenbergiana, Larrea divaricata, Mimozyganthus carinatus, and Moya spinosa) were selected, and, on average, 30 individuals per species were harvested. Their total individual dry biomass was related with morphometric variables using regression analysis.Results
Crown area as well as crown-shaped variables proved to be the variables with the best performance for both species-specific and multispecies shrub models. These allometric variables are thus recommended for standardized shrub biomass assessments.Conclusion
By accounting for the shrub component of the vegetation, our models provide a way to improve the quantification of biomass and carbon in semiarid open forest and woodlands. 相似文献93.
Giovanni Di Matteo Paolo De Angelis Enrico Brugnoli Paolo Cherubini Giuseppe Scarascia-Mugnozza 《Annals of Forest Science》2010,67(5):510-510
94.
Amara Evangeline Unigwe Enrico Doria Patrick Adebola Abe. S Gerrano Michael Pillay 《Journal of Crop Improvement》2018,32(2):208-224
Bambara groundnut is a leguminous crop that originated in West Africa. It is a drought-tolerant crop and has the potential to provide improved food and nutritional security in the dry areas of Africa. However, the plant contains anti-nutritional factors that affect its food value chain. The objective of this study was to assess the content of four major anti-nutritional factors in 30 bambara groundnut accessions in South Africa. The seeds of the bambara groundnut landraces were ground to make a fine powder and assessed for condensed tannins (CTs), phytic acid phosphate (PAP), polyphenol, and trypsin inhibitor content. Each assay was done in triplicate. The content of the four anti-nutritional compounds varied widely among the bambara groundnut accessions. The mean values for CTs ranged between 0.2 and 6.2 mg/g of prodephinidin equivalent, whereas that of the PAP was between 1.4 and 4.9 mg/g. A low mean polyphenol content of 0.4 mg/g of GA (gallic acid) equivalent was observed among the accessions. The level of trypsin inhibitor ranged from 5.3 to 73.4 TI/mg. With the exception of CTs and trypsin inhibitor, no significant correlation was observed among the four anti-nutritional factors assessed in this study. Generally, higher levels of anti-nutrients were observed in this study compared with certain studies reported earlier. 相似文献
95.
COMPUTED TOMOGRAPHIC FEATURES OF INCISOR PSEUDO‐ODONTOMAS IN PRAIRIE DOGS (CYNOMYS LUDOVICIANUS) 下载免费PDF全文
Igor Pelizzone Francesco Di Ianni Antonella Volta Giacomo Gnudi Sabrina Manfredi Mara Bertocchi Enrico Parmigiani 《Veterinary radiology & ultrasound》2017,58(3):273-283
Maxillary incisor pseudo‐odontomas are common in pet prairie dogs and can cause progressive respiratory obstruction, while mandibular pseudo‐odontomas are rarely clinically significant. The aim of this retrospective cross‐sectional study was to describe CT features of maxillary and mandibular incisor pseudo‐odontomas vs. normal incisors in a group of pet prairie dogs. All pet prairie dogs with head CT scans acquired during the period of 2013–2015 were included. A veterinary radiologist who was aware of final diagnosis reviewed CT scans and recorded qualitative features of affected and normal incisors. Mean density values for the pulp cavity and palatal and buccal dentin were also recorded. A total of 16 prairie dogs were sampled (12 normal maxillary incisors, 20 confirmed maxillary incisor pseudo‐odontomas, 20 normal mandibular incisors, 12 presumed mandibular incisor pseudo‐odontomas). Maxillary incisors with confirmed pseudo‐odontomas had a significantly hyperattenuating pulp and dentin in the reserve crown and apical zone, when compared to normal maxillary incisors. Pseudo‐odontomas appeared as enlargements of the apical zone with a globular/multilobular hyperattenuating mass formation haphazardly arranged, encroaching on midline and growing caudally and ventrally. Presumed mandibular incisor pseudo‐odontomas had similar CT characteristics. In 60% of prairie dogs with maxillary incisor pseudo‐odontomas, the hard palate was deformed and the mass bulged into the oral cavity causing loss of the palatine bone. The common nasal meatus was partially or totally obliterated in 81.8% of prairie dogs with maxillary pseudo‐odontomas. Findings supported the use of CT for characterizing extent of involvement and surgical planning in prairie dogs with pseudo‐odontomas. 相似文献
96.
97.
Gianni Cortecci Tiziano Boschetti Enrico Dinelli Roberto Cabella 《Water, air, and soil pollution》2008,192(1-4):85-103
The geochemical characteristics of rills draining pyrite-chalcopyrite tailings impoundments and of bordering streams were investigated at the ophiolite-hosted Libiola and Vigonzano abandoned massive sulphide mines, northern Apennines Italy. Water samples were analysed for major and trace chemical composition, hydrogen and oxygen isotope composition, and sulphur isotope composition of aqueous sulphate. Sulphur isotope composition was determined also for some samples of ore sulphides. At Libiola, the newly acquired chemical results on waters corroborate those from previous investigations, thus providing additional support to existing geochemical models in terms of metal distribution, solid phases precipitation, reaction path modelling and mixing reaction paths, and environmental problems. At Vigonzano, the chemical characteristics of waters are similar to those at Libiola. In both localities, solution-secondary phase equilibria estimated using an updated thermodynamic dataset account for mineralogy in the field, including poorly crystalline phases like jurbanite and hydrowoodwardite. The hydrogen and oxygen isotope composition of waters at Libiola and Vigonzano agrees with their meteoric origin. Acid to neutral mine waters do not show any significant isotope shift with respect to the initial water, in spite of the oxidation of even large amounts of pyrite/chalcopyrite ore. The sulphur isotope composition of aqueous sulphate in mine rills at Libiola (δ 34S?=?5.6 to 8.5‰; mean 6.5‰) matches that of massive sulphide ore (δ 34S?=??0.5 to 6.7‰; mean 5.8‰), in keeping with the supergenic origin of the sulphate and related isotope effects in the sulphide oxidation process. Sulphate in mine waters at Vigonzano displays lower δ 34S values in the range 0.6 to 1.5‰. The δ 34S signature of massive ore specimens is within the range reported for most volcanic-hosted massive sulphide deposits, including Cyprus-type deposits. 相似文献
98.
Venneria E Fanasca S Monastra G Finotti E Ambra R Azzini E Durazzo A Foddai MS Maiani G 《Journal of agricultural and food chemistry》2008,56(19):9206-9214
The genetic modification in fruit and vegetables could lead to changes in metabolic pathways and, therefore, to the variation of the molecular pattern, with particular attention to antioxidant compounds not well-described in the literature. The aim of the present study was to compare the quality composition of transgenic wheat ( Triticum durum L.), corn ( Zea mays L.), and tomato ( Lycopersicum esculentum Mill.) to the nontransgenic control with a similar genetic background. In the first experiment, Ofanto wheat cultivar containing the tobacco rab1 gene and nontransgenic Ofanto were used. The second experiment compared two transgenic lines of corn containing Bacillus thuringiensis "Cry toxin" gene (PR33P67 and Pegaso Bt) to their nontransgenic forms. The third experiment was conducted on transgenic tomato ( Lycopersicum esculentum Mill.) containing the Agrobacterium rhizogenes rolD gene and its nontransgenic control (cv. Tondino). Conventional and genetically modified crops were compared in terms of fatty acids content, unsaponifiable fraction of antioxidants, total phenols, polyphenols, carotenoids, vitamin C, total antioxidant activity, and mineral composition. No significant differences were observed for qualitative traits analyzed in wheat and corn samples. In tomato samples, the total antioxidant activity (TAA), measured by FRAP assay, and the naringenin content showed a lower value in genetically modified organism (GMO) samples (0.35 mmol of Fe (2+) 100 g (-1) and 2.82 mg 100 g (-1), respectively), in comparison to its nontransgenic control (0.41 mmol of Fe (2+) 100 g (-1) and 4.17 mg 100 g (-1), respectively). On the basis of the principle of substantial equivalence, as articulated by the World Health Organization, the Organization for Economic Cooperation and Development, and the United Nations Food and Agriculture Organization, these data support the conclusion that GM events are nutritionally similar to conventional varieties of wheat, corn, and tomato on the market today. 相似文献
99.
Buscaroli Enrico Sciubba Luigi Falsone Gloria Cavani Luciano Brecchia Matteo Argese Emanuele Marzadori Claudio Pourrut Bertrand Braschi Ilaria 《Journal of Soils and Sediments》2019,19(7):3098-3107
Journal of Soils and Sediments - Canal dredging and shaping produce considerable amounts of sediments whose reuse on- and off-site depends on their pollution level. This study explores the... 相似文献
100.
Massimo Saccomani Piergiorgio Stevanato Daniele Trebbi J. Mitchell McGrath Enrico Biancardi 《Euphytica》2009,169(1):19-29
Beta vulgaris genetic resources are essential for broadening genetic base of sugar beet and developing cultivars adapted to adverse environmental
conditions. Wild beets (sea beets, B. vulgaris spp. maritima and their naturalized introgressions with cultivated beets known as ruderal beets) harbor substantial genetic diversity that
could be useful for beet improvement. Here, we compared molecular and morpho-physiological traits of wild beets collected
on the Adriatic coast of Italy with sugar beet using eight primer-pairs amplifying 194 polymorphic fragments and four root
traits (glucose and fructose content in the root tip, root elongation rate, number of the of root tips, total root length
and its distribution among diameters ranges). Genetic diversity was higher in the sea beet accession, which may be due to
the highly variable selection pressures that occur in heterogeneous ecological niches, compared with the ruderal and cultivated
beets. Sea and sugar beet accessions showed contrasting root patterns in response to sulfate deprivation: sugar beet showed
an increase of reducing sugars in the root tips and higher root elongation rate, and the sea beet accession showed an increase
in root tip number, total root length and fine root length (average diameter < 0.5 mm). The ruderal beet showed intermediary
responses to sea and sugar beet accessions. AFLP and morpho-physiological cluster analyzes showed sea, ruderal and cultivated
beets to be genetically distinct groups. The results of this study indicate variability in response to sulfate deprivation
is present in undomesticated beets that could be deployed for sugar beet improvement. 相似文献