全文获取类型
收费全文 | 415篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
林业 | 25篇 |
农学 | 4篇 |
基础科学 | 1篇 |
120篇 | |
综合类 | 17篇 |
农作物 | 36篇 |
水产渔业 | 15篇 |
畜牧兽医 | 183篇 |
园艺 | 10篇 |
植物保护 | 19篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 17篇 |
2020年 | 12篇 |
2019年 | 28篇 |
2018年 | 18篇 |
2017年 | 12篇 |
2016年 | 17篇 |
2015年 | 13篇 |
2014年 | 17篇 |
2013年 | 24篇 |
2012年 | 32篇 |
2011年 | 35篇 |
2010年 | 14篇 |
2009年 | 14篇 |
2008年 | 31篇 |
2007年 | 24篇 |
2006年 | 23篇 |
2005年 | 20篇 |
2004年 | 26篇 |
2003年 | 15篇 |
2002年 | 15篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1996年 | 1篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有430条查询结果,搜索用时 687 毫秒
131.
Sarah M Weber Eric T Hostnik Wm Tod Drost Alessandra N Hamlin Marc A Ledesma Lauren Timperman Ashley C. Hechler Lynette K Cole 《Veterinary radiology & ultrasound》2020,61(4):444-452
Chiari‐like malformation (CM) and syringomyelia (SM) are common illnesses that can cause debilitating neuropathic pain in Cavalier King Charles spaniels (CKCS). The current imaging modality to screen CKCS for CM/SM is MRI of the brain and cervical spine. Magnetic resonance imaging provides good soft tissue detail and contrast of the cerebellum and cervical spinal cord. Computed tomography (CT) is another cross‐sectional imaging technique that facilitates brain and neck evaluation; however, soft tissue resolution does not match that of MRI. Computed tomography benefits include identification of concurrent craniocervical junction anomalies (atlantooccipital overlap) and shorter imaging/anesthesia times with the ability to use only sedation. The aim of this retrospective, method comparison study is to assess the utility of multidetector CT for screening CM and SM in CKCS as compared to high‐field MRI. Three groups of observers with different levels of experience graded CM and SM based on the British Veterinary Association/Kennel Club CM/SM classification criteria. Thirty CKCS underwent multidetector CT and 3 Tesla MRI studies. Computed tomography and MRI studies were reviewed at different timepoints to minimize bias. Computed tomography has lower Cohen's Kappa agreement for each observer group compared to MRI. The intraclass correlation coefficient averaging CM and SM for all groups was excellent using MRI, while CT was poor for SM and moderate for cerebellar herniation. Greater observer experience resulted in a higher agreement for CT and MRI. Magnetic resonance imaging should remain the standard for screening of CM and SM as CT can result in misclassification and greater disagreement. 相似文献
132.
Eliene Matos Silva Natoniel Franklin de Melo Alessandra Monteiro Salviano Mendes Francisco Pinheiro de Araújo Leonor Costa Maia 《Journal of plant nutrition》2015,38(3):431-442
The Caatinga is a unique biome that encompasses nearly 11% of Brazil's territory and contains diverse vegetation composed of trees and bushes that have been scarcely studied from the economic perspective. In this context, Passiflora setacea may constitute a strategic alternative for agriculture because it produces fruit that has commercial potential and is tolerant to some diseases. Some species of Passiflora show more robust growth when associated with arbuscular mycorrhizal fungi (AMF) and are dependent on mycorrhization. In this study, the response of P. setacea to phosphate (P) fertilization and mycorrhization with Claroideoglomus etunicatum was evaluated. The experimental design included eight replicates of four randomized treatments: non-inoculated plants (NI), plants fertilized with phosphorus (P), mycorrhized plants (AMF), and plants that were both fertilized and mycorrhized (P+AMF). The plant height, leaf number, leaf area, fresh biomass (FB), and dry biomass (DB) of the shoots and roots, nutrient content, mycorrhizal colonization (MC), and the number of glomerospores (NG) in the rhizosphere were evaluated. The MC and the NG were reduced by phosphate fertilization. The development of the mycorrhized plants was significantly better than the NI and P treated plants for all of the variables tested. Inoculation with C. etunicatum promoted the growth of P. setacea seedlings even in the absence of phosphate fertilization, reducing production costs and strengthening the potential of P. setacea as a viable agricultural alternative for the semiarid region. 相似文献
133.
Reddy KD Rao BV Babu GS Kumar BR Braca A Vassallo A De Tommasi N Rao GV Rao AV 《Fitoterapia》2011,82(7):1039-1043
Phytochemical investigation of Caralluma adscendens var. gracilis and Caralluma pauciflora (Asclepiadaceae) whole plant extracts allowed to isolate one pregnane glycoside and two pregnanes characterized as 12β,20-O-dibenzoyl-5α,6-dihydrosarcostin β-oleandropyranosyl-(1→4)-β-cymaropyranosyl-(1→4)-β-digitoxypyranosyl-(1→4)-β-cymaropyranosyl-(1→4)-β-cymaropyranoside (1), 12β-O-benzoyl-3β,11α,14β,20R-pentahydroxy-pregn-5-ene (2), and 11α-O-benzoyl-3β,12β,14β,20R-pentahydroxy-pregn-5-ene (3), respectively. Their structural characterization was obtained on the basis of extensive NMR spectral studies. Three known pregnane glycosides along with lupeol and β-sitosterol were also isolated and characterized. 相似文献
134.
Phytochemical investigation of Helleborus niger L. (Ranunculaceae) leaf methanol extract allowed to isolate a phenolic glucoside derivative and two flavonoid glycosides characterized as phenyllactic acid 2-O-β-d-glucopyranoside (1), quercetin 3-O-2-(E-caffeoyl)-α-l-arabinopyranosyl-(1 → 2)-β-d-glucopyranoside-7-O-β-d-glucopyranoside (2), and kaempferol 3-O-α-l-arabinopyranosyl-(1 → 2)-β-d-galactopyranoside-7-O-β-d-glucopyranoside (3), respectively. Compounds 1 and 2 were isolated for the first time and their structural characterization was obtained on the basis of extensive NMR spectral studies. 相似文献
135.
Alessandra Marti Xiaoxue Qiu Tonya C. Schoenfuss Koushik Seetharaman 《Cereal Chemistry》2015,92(5):434-440
Intermediate wheatgrass (IWG) (Thinopyrum intermedium) is a perennial grass with desirable agronomic traits and positive effects on the environment. It has high fiber and protein contents, which increase the interest in using IWG for human consumption. In this study, IWG flour was blended with refined wheat at four IWG‐to‐wheat ratios (0:100, 50:50, 75:25, and 100:0). Samples were analyzed for proximate composition, microstructure features, pasting properties (Micro Visco‐Amylo‐Graph device), protein solubility, and total and accessible thiols. Gluten aggregation properties (GlutoPeak tester) and mixing profile (Farinograph‐AT device) were also evaluated. IWG flour enrichment increased the pasting temperature and decreased the peak viscosity of blended flours. IWG proteins exhibited higher solubility than wheat, with a high amount of accessible and total thiols. The GlutoPeak tester highlighted the ability of IWG proteins to aggregate and generate torque. Higher IWG flour enrichment resulted in faster gluten aggregation with lower peak torque, suggesting weakening of wheat gluten strength. Finally, the addition of IWG to refined wheat flour resulted in a decrease in dough development time and an increase in consistency, likely because of the higher levels of fiber in IWG. The 50% IWG flour enrichment represents a good compromise between nutritional improvement and maintenance of the pasting properties, protein characteristics, and gluten aggregation kinetics. 相似文献
136.
Effects of rootstock on the composition of bergamot (Citrus bergamia Risso et Poiteau) essential oil
Verzera A Trozzi A Gazea F Cicciarello G Cotroneo A 《Journal of agricultural and food chemistry》2003,51(1):206-210
This paper reports the composition of bergamot oils obtained from plants grafted on the following rootstocks: sour orange, Carrizo citrange, trifoliate orange, Alemow, Volkamerian lemon, and Troyer citrange. The aim of this study is to evaluate the possibility of using rootstocks other than sour orange, checking their effect on the composition of the essential oil. Results are reported for analysis of 203 bergamot oils during the years 1997-1998, 1998-1999, and 1999-2000. The oils were analyzed by HRGC and HRGC/MS; 78 components were identified, and the results were in agreement with those reported in the literature for the Calabrian bergamot oils obtained from industry. Because of the quality of their essential oils, Alemow and Volkamerian lemon can be considered as substitutes for sour orange rootstocks. 相似文献
137.
Ilaria Marotti Alessandra Bonetti Maurizio Minelli Pietro Catizone Giovenni Dinelli 《Genetic Resources and Crop Evolution》2007,54(1):175-188
Randomly amplified polymorphic DNA (RAPD), inter-simple sequence repeat (ISSR) and a semi-random PCR system were used to analyze
the genetic diversity of 16 Italian common bean landraces and their relationship to four commercial cultivars. Of the primers
tested, 8 ISSR, 6 RAPD and 7 semi-random primers produced polymorphic and reproducible DNA fragments. A higher proportion
of polymorphic bands were observed using ISSR (85%) and semi-random (90%) primers than RAPD (69%) method. The combination
of any two semi-random markers allowed the identification of all 20 bean genotypes. In contrast ISSR (except for primer (CAC)3GC) and RAPD markers appeared to be less informative as more than two markers were necessary to achieve the same diagnostic
level. Moreover, 7 ISSR, 2 RAPD and 8 semi-random exclusive bands were identified as putative population-specific markers.
Semi-random and ISSR derived dendrograms showed similar tendencies in terms of genetic relatedness, whereas clustering of
genotypes within groups was not similar when compared with the RAPD technique. Despite the different ability to resolve genetic
variation among the investigated landraces, two major clusters with less than 60% (ISSR) and 40% (RAPD and semi-random) genetic
similarity were formed with all three marker systems. The two groups were correlated with the phaseolin patterns and seed
size of the landraces. The analysis showed that the cultivar ȁ8Lingua di Fuocoȁ9 and most of the landraces (13 out of 16)
collected in Italy belong to the Andean gene pool, whereas only the three populations from Pratomagno belong to the Middle
American gene pool. 相似文献
138.
139.
140.
Sousa LA Pires HB Soares SF Ferri PH Ribas P Lima EM Furlong J Bittencourt VR Perinotto WM Borges LM 《Veterinary parasitology》2011,175(3-4):320-324
The use of a concentrate emulsion of Melia azedarach green fruits and a suspension of the fungus Beauveria bassiana was evaluated in the control of Rhipicephalus microplus on artificially infested cattle. The evaluation was conducted following the protocol established by the Brazilian Agriculture Ministry. Five groups of 4 or 5 animals were allocated to one of the following treatments: emulsion concentrate of M. azedarach at 0.25% (T AZED 0.25%), emulsion concentrate of M. azedarach at 0.5% (T AZED 0.5%), B. bassiana at 2.4 × 10(8) conidia (T BASS), association of the concentrate of M. azedarach at 0.25% with B. bassiana at 2.4 × 10(8) conidia (T AZED 0.25%+BASS), and control (untreated). The association of the two compounds provided better results than any one isolated treatment, indicating compatibility or perhaps a synergy between M. azedarach and B. bassiana. This treatment resulted in fewer engorged females (129 ± 70) than in the control group (233 ± 82), showing high performance against all developmental stages of the tick. Results revealed an apparent synergistic effect of M. azedarach and B. bassiana in the control of R. microplus that should be further investigated. 相似文献