全文获取类型
收费全文 | 233篇 |
免费 | 11篇 |
专业分类
林业 | 5篇 |
农学 | 5篇 |
91篇 | |
综合类 | 19篇 |
农作物 | 16篇 |
水产渔业 | 9篇 |
畜牧兽医 | 67篇 |
园艺 | 6篇 |
植物保护 | 26篇 |
出版年
2022年 | 3篇 |
2021年 | 8篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 13篇 |
2015年 | 9篇 |
2014年 | 12篇 |
2013年 | 9篇 |
2012年 | 19篇 |
2011年 | 16篇 |
2010年 | 11篇 |
2009年 | 8篇 |
2008年 | 13篇 |
2007年 | 15篇 |
2006年 | 11篇 |
2005年 | 16篇 |
2004年 | 12篇 |
2003年 | 13篇 |
2002年 | 14篇 |
1996年 | 1篇 |
1992年 | 3篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1986年 | 2篇 |
1983年 | 1篇 |
排序方式: 共有244条查询结果,搜索用时 12 毫秒
11.
Utilization of the genetic resources of wild species to create a nontransgenic high flavonoid tomato
Willits MG Kramer CM Prata RT De Luca V Potter BG Steffens JC Graser G 《Journal of agricultural and food chemistry》2005,53(4):1231-1236
Flavonoids represent a large and important group of plant natural products that are ubiquitous in the plant kingdom. Epidemiological studies have shown the health benefits of a diet high in flavonoids. However, the dietary intake of flavonoids in most western populations is limited, creating a need to find alternative food sources for these polyphenolic secondary metabolites. The domestication of many of our cultivated food crops has resulted in alterations in the biosynthetic pathways of many essential micronutrients and vitamins through inadvertent counterselection against nutritional traits in favor of agronomic ones. Flavonoids are nearly absent from fruits of cultivated tomato (Lycopersicon esculentum Mill.), a major vegetable in human diets. Previous attempts to restore the flavonoid pathway in tomato fruits have been limited to transgenic strategies, suggesting that the problem was intractable through traditional methods. Here, we describe for the first time a nontransgenic metabolic engineering approach to developing a high flavonoid tomato using a wild tomato species (Lycopersicon pennelliiv. puberulum) and demonstrate the opportunities for restoring functional pathways using the genetic resources of wild species, resulting in production of healthier foods. 相似文献
12.
Bicanic D Swarts J Luterotti S Helander P Fogliano V Anese M 《Journal of agricultural and food chemistry》2005,53(9):3295-3299
This study reports on the first use of the "optothermistor" as a novel, precise, fast, and low-cost detector of lycopene in a wide range of commercially available processed-tomato products. The quantitative performance of the new device was evaluated by comparing data obtained to that acquired by conventional methods, namely, absorption spectrophotometry and high-performance liquid chromatography (HPLC); the linear correlation was high (R = 0.98). The variation of data obtained with the optothermistor in a series of consecutive measurements performed with the same loading of the sample was better than 1%. However, the repeatability (RSD 0.5-9.0%, n = 3-5) achieved with the optothermistor by independent analyses (multiple loading) is comparable to that of HPLC and spectrophotometry. Results of the studies performed on the 19 products derived from tomatoes demonstrated that the optothermistor is suitable for selective, accurate, precise, and simple determination of lycopene (range = 7-75 mg/100 g of product weight) without the need for a sample pretreatment step. The estimated sensitivity of the present optothermistor is 2 mg of lycopene/100 g of product. 相似文献
13.
Dugo G La Pera L Lo Turco V Mavrogeni E Alfa M 《Journal of agricultural and food chemistry》2003,51(13):3722-3725
The aim of this work was to determine the selenium content in nut samples by cathodic stripping potentiometry. Dry-powdered nuts were digested by HNO(3) and dissolved with concentrated hydrochloric acid. To avoid the interference of natural oxygen, the potentiometric determination of selenium was carried out in an electrolyte solution consisting of 2 M CaCl(2) and 4 M HCl. The analysis was executed applying an electrolysis potential of -150 mV for 60 s and a constant current of -30 microA. Under these conditions, detection limits lower than 1.0 ng g(-)(1) were obtained for selenium analysis in nuts. The relative standard deviation of these measurements (expressed as rsd %) ranged from 0.44 to 0.88% while recoveries ranged from 90.2 to 95.3%. The results obtained with the proposed method were compared with those obtained via hydride vapor generation atomic absorption spectroscopy, a common method for determining selenium. The results of the two methods agreed within 5% for almond, hazelnut, and pistachio samples. The mean concentrations of selenium determined in Sicilian samples of almond, hazelnut, and pistachio were 531 +/- 1, 865 +/- 1, and 893 +/- 4 microg/kg, respectively. 相似文献
14.
Cengiz Gokbulut Hande Sultan Yalinkilinc Dilek Aksit Vincenzo Veneziano 《Canadian journal of veterinary research》2014,78(4):316-320
Since there is no registered anthelmintic drug available for use in goats, extra-label use of drugs is a common practice in most countries. The aim of the present study was to compare the pharmacokinetic disposition of levamisole (LVM)-oxyclozanide (OXZ) combination in sheep and goats following per os administration. Goats (n = 8) and sheep (n = 8) 12- to 16-months-old were used for this study. The animals received tablet formulation of LVM and OXZ combination orally at a dose of 7.5 mg/kg and 15 mg/kg body weight, respectively. Blood samples were collected by jugular vein at different times between 5 min and 120 h after drug administrations. The plasma concentrations of LVM and OXZ were analyzed by HPLC following liquid-liquid phase extraction procedures. The plasma concentrations and systemic availabilities of both LVM and OXZ in goats were lower and the plasma persistence of LVM was shorter compared with those observed in sheep. Terminal half-lives (t1/2λz) of both molecules are shorter in goats compared with those in sheep. Goats treated with LVM-OXZ combination at the recommended dose for sheep may result in a reduced efficacy, because of under-dosing, which may increase the risk of drug resistance in parasites. Increased or repeated dose could be a strategy to provide higher plasma concentration and thus to improve the efficacy against the target parasites in goats compared with sheep. However, some adverse reactions may occur since LVM has relatively very narrow therapeutic index due to its nicotine-like structure and effect. 相似文献
15.
Franco Bettarini Pietro Massardo Paolo Piccardi Vincenzo Caprioli 《Pest management science》1986,17(5):465-472
A new class of compounds derived from hydroquinone ethers showed high and predominantly ovicidal activity against the two-spotted spider mite, Tetranychus urticae Koch. The sequence of compounds synthesised and the factors which appeared to have contributed most to the discovery of these promising acaricides are presented. 相似文献
16.
Giuseppina Chianese Ernesto Fattorusso Masteria Yunovilsa Putra Barbara Calcinai Giorgio Bavestrello Aniello Schiano Moriello Luciano De Petrocellis Vincenzo Di Marzo Orazio Taglialatela-Scafati 《Marine drugs》2012,10(11):2435-2447
Leucettamols, bifunctionalized sphingoid-like compounds obtained from a marine sponge Leucetta sp., act as non-electrophilic activators of the TRPA1 channel and potent inhibitors of the icilin-mediated activation of the TRPM8 channel, while they are inactive on CB1, CB2 and TRPV1 receptors. Leucettamols represent the first compounds of marine origin to target TRPA1 and the first class of natural products to inhibit TRPM8 channels. The preparation of a small series of semi-synthetic derivatives revealed interesting details on the structure-activity relationships within this new chemotype of simple acyclic TRP modulators. 相似文献
17.
Kaouane N Porte Y Vallée M Brayda-Bruno L Mons N Calandreau L Marighetto A Piazza PV Desmedt A 《Science (New York, N.Y.)》2012,335(6075):1510-1513
Posttraumatic stress disorder (PTSD) is characterized by a hypermnesia of the trauma and by a memory impairment that decreases the ability to restrict fear to the appropriate context. Infusion of glucocorticoids in the hippocampus after fear conditioning induces PTSD-like memory impairments and an altered pattern of neural activation in the hippocampal-amygdalar circuit. Mice become unable to identify the context as the correct predictor of the threat and show fear responses to a discrete cue not predicting the threat in normal conditions. These data demonstrate PTSD-like memory impairments in rodents and identify a potential pathophysiological mechanism of this condition. 相似文献
18.
Massimo Iovino Mirko Castellini Vincenzo Bagarello Giuseppe Giordano 《Land Degradation \u0026amp; Development》2016,27(2):200-210
Both capacitive indicators derived from the water retention curve and dynamic measurements of the flow‐weighted mean pore radius, R0, were used to assess the soil physical quality of two agricultural areas (cropland and olive orchard) and two natural areas (grassland and managed woodlot plantation) potentially subject to soil degradation. The overall idea of the study was to investigate whether a dynamic indicator quantitatively derived from hydraulic conductivity measurements could be used to supplement the traditionally applied capacitive indicators retrieved from water retention measurements. According to the available criteria, only the surface layer of the cropland site showed optimal soil physical quality. In the grassland and woodlot sites, the physical quality was deteriorated also as a consequence of compaction because of grazing. Overall, the physical quality was better in tilled than nontilled soils. The optimal soil in terms of capacitive indicators had hydraulic conductivity close to saturation that was intermediate among the different land uses, and it remained 1·3–1·9 times higher than that observed in the natural sites even when the largest pores emptied. A depth effect on R0 was observed only when larger macropores were activated. It was suggested that water transmission parameters are more affected by changes in large pore domain. The plant available water content and Dexter's S‐index showed inverse statistically significant regressions with R0. The empirical relationships were physically convincing given that, at increasing R0, the contribution of macropores increases, water is transmitted faster below the root zone and the soil's ability to store water is reduced. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
19.
Borrelli RC Visconti A Mennella C Anese M Fogliano V 《Journal of agricultural and food chemistry》2002,50(22):6527-6533
Melanoidins, the brown polymers formed through Maillard reaction during coffee roasting, constitute up to 25% of the coffee beverages' dry matter. In this study chemical characterization of melanoidins obtained from light-, medium-, and dark-roasted coffee beans, manufactured from the same starting material, was performed. Melanoidins were separated by gel filtration chromatography and studied by MALDI-TOF mass spectrometry. Results showed that the amount of melanoidins present in the brews increased as the intensity of the thermal treatment increased, while their molecular weight decreased. The antioxidant activity of melanoidins isolated from the different brews was studied by using different methodologies. Melanoidins antiradical activity determined by ABTS(*)(+) and DMPD(*)(+) assays decreased as the intensity of roasting increased, but the ability to prevent linoleic acid peroxidation was higher in the dark-roasted samples. Data suggest that melanoidins must be carefully considered when the relevance of coffee intake in human health is studied. 相似文献
20.
Vincenzo Montesano Donatella Negro Giulio Sarli Giuseppina Logozzo Pierluigi Spagnoletti Zeuli 《Genetic Resources and Crop Evolution》2012,59(5):701-716
A collecting expedition has been carried out in the inland areas of the Basilicata Region, South Italy. Each of the 14 selected municipalities was subdivided in three strata based on the geographical distribution of population and orography: 1. city boundaries, 2. group of country houses, 3. isolated farm houses. Five sites were selected within each stratum/town for a total of 185 sites. In 101 sites crop species germplasm was collected and the farmer-maintainers were interviewed. Altogether 350 accessions were collected, the most common species were Capsicum annuum, Lycopersicon esculentum and Phaseolus vulgaris. A significant number of landraces are still preserved on farm, mostly in isolated farm houses (average age of farmers: 60?years) adopting traditional farming systems but a number of young farmers were also present. Perspectives for on farm conservation and management are discussed and public economic support for “farmer-maintainers” proposed. 相似文献