全文获取类型
收费全文 | 4029篇 |
免费 | 213篇 |
国内免费 | 2篇 |
专业分类
林业 | 285篇 |
农学 | 150篇 |
基础科学 | 14篇 |
1073篇 | |
综合类 | 196篇 |
农作物 | 322篇 |
水产渔业 | 442篇 |
畜牧兽医 | 1372篇 |
园艺 | 85篇 |
植物保护 | 305篇 |
出版年
2024年 | 2篇 |
2023年 | 37篇 |
2022年 | 74篇 |
2021年 | 170篇 |
2020年 | 162篇 |
2019年 | 205篇 |
2018年 | 158篇 |
2017年 | 169篇 |
2016年 | 157篇 |
2015年 | 125篇 |
2014年 | 184篇 |
2013年 | 274篇 |
2012年 | 331篇 |
2011年 | 318篇 |
2010年 | 185篇 |
2009年 | 166篇 |
2008年 | 271篇 |
2007年 | 284篇 |
2006年 | 187篇 |
2005年 | 159篇 |
2004年 | 133篇 |
2003年 | 131篇 |
2002年 | 132篇 |
2001年 | 22篇 |
2000年 | 19篇 |
1999年 | 19篇 |
1998年 | 14篇 |
1997年 | 13篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1980年 | 3篇 |
1977年 | 3篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1969年 | 3篇 |
1966年 | 4篇 |
1955年 | 2篇 |
排序方式: 共有4244条查询结果,搜索用时 15 毫秒
961.
Cocoa-enriched diet enhances antioxidant enzyme activity and modulates lymphocyte composition in thymus from young rats 总被引:3,自引:0,他引:3
Ramiro-Puig E Urpí-Sardà M Pérez-Cano FJ Franch A Castellote C Andrés-Lacueva C Izquierdo-Pulido M Castell M 《Journal of agricultural and food chemistry》2007,55(16):6431-6438
Cocoa is a rich source of flavonoids, mainly (-)-epicatechin, (+)-catechin, and procyanidins. This article reports the effect of continuous cocoa intake on antioxidant capacity in plasma and tissues, including lymphoid organs and liver, from young rats. Weaned Wistar rats received natural cocoa (4% or 10% food intake) for three weeks, corresponding to their infancy. Flavonoid absorption was confirmed through the quantification of epicatechin metabolites in urine. Total antioxidant capacity (TAC) and the activity of antioxidant enzymes, superoxide dismutase (SOD) and catalase, were examined. Cocoa intake enhanced TAC in all tissues especially in thymus. Moreover, thymus SOD and catalase activities were also dose-dependently increased by cocoa. It was also analyzed whether the enhanced antioxidant system in thymus could influence its cellular composition. An increase in the percentage of thymocytes in advanced development stage was found. In summary, cocoa diet enhances thymus antioxidant defenses and influences thymocyte differentiation. 相似文献
962.
Orfanos P Naska A Trichopoulos D Slimani N Ferrari P van Bakel M Deharveng G Overvad K Tjønneland A Halkjaer J Santucci de Magistris M Tumino R Pala V Sacerdote C Masala G Skeie G Engeset D Lund E Jakszyn P Barricarte A Chirlaque MD Martinez-Garcia C Amiano P Quirós JR Bingham S Welch A Spencer EA Key TJ Rohrmann S Linseisen J Ray J Boeing H Peeters PH Bueno-de-Mesquita HB Ocke M Johansson I Johansson G Berglund G Manjer J Boutron-Ruault MC Touvier M Clavel-Chapelon F Trichopoulou A 《Public health nutrition》2007,10(12):1515-1525
963.
Veiga TA Silva SC Francisco AC Filho ER Vieira PC Fernandes JB Silva MF Müller MW Lotina-Hennsen B 《Journal of agricultural and food chemistry》2007,55(10):4217-4221
Four natural products were isolated from the fungus Botryosphaeria rhodina, and their effects on photosynthesis were tested. Only lasiodiplodin (1) inhibited ATP synthesis and electron flow from water to methylviologen; therefore, it acts as a Hill reaction inhibitor in freshly lysed spinach thylakoids. Photosystem I and II and partial reactions as well as ATPase were measured in the presence of 1. Three new different sites of 1 interaction and inhibition were found: one at CF1, the second in the water-splitting enzyme, and the third at the electron-transfer path between P680 and QA; these targets are different from that of the synthetic herbicides present. Electron transport chain inhibition by 1 was corroborated by fluorescence induction kinetics studies. 相似文献
964.
Sarpietro MG Spatafora C Tringali C Micieli D Castelli F 《Journal of agricultural and food chemistry》2007,55(9):3720-3728
The interaction of resveratrol (trans-3,5,4'-trihydroxystilbene) and two of its derivatives (3,5,4'-tri-O-methylresveratrol and 3,5,4'-tri-O-triacetylresveratrol) with biomembrane models, represented by dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles (MLV), has been studied by differential scanning calorimetry (DSC). The analysis of MLV prepared in the presence of increasing molar fraction of such compounds has been carried out to reveal their maximum interaction with biomembrane models. The results from these studies have been compared with kinetic experiments results, in order to detect the entity and rate of compound absorption by the biomembrane models. The findings indicate that the compounds affected the thermotropic properties of DMPC MLV by suppressing the pretransition peak and broadening the DMPC main phase transition calorimetric peak and shifting it to lower temperatures. The order of effectiveness found was resveratrol > trimethylresveratrol > triacetylresveratrol. The kinetic experiments reveal that in an aqueous medium the absorption of resveratrol by the biomembranes models is allowed, whereas the absorption of its derivatives is hindered; in contrast when a lipophilic medium is employed, all three compounds are easily absorbed. 相似文献
965.
Affinity purification of copper-chelating peptides from sunflower protein hydrolysates 总被引:1,自引:0,他引:1
Megías C Pedroche J Yust MM Girón-Calle J Alaiz M Millan F Vioque J 《Journal of agricultural and food chemistry》2007,55(16):6509-6514
Copper-chelating peptides were purified from sunflower protein hydrolysates by affinity chromatography using immobilized copper. A variety of protein hydrolysates were obtained by incubation with the proteases Alcalase and Flavourzyme for different periods of time. Chelating activity was indirectly determined by measuring the inhibitory effect of hydrolysates on the oxidation of beta-carotene by copper. Copper-binding peptides purified from the two hydrolysates that inhibited oxidation by copper the most contained 25.4 and 42.0% histidine and inhibited beta-carotene oxidation 8 and 3 times more than the original hydrolysates, which had 2.4 and 2.6% histidine, respectively. Thus, histidine content is not the only factor involved in antioxidant activity, and probably other factors such as peptide size and amino acid sequence are also important. This work shows that affinity chromatography can be used for the purification of copper-chelating peptides and probably other metals of nutritional interest such as calcium, iron, and zinc. In addition to their antioxidant potential, chelating peptides are of nutritional interest because they increase bioavailability of minerals. 相似文献
966.
Almenar E Auras R Wharton P Rubino M Harte B 《Journal of agricultural and food chemistry》2007,55(17):7205-7212
Many naturally occurring plant volatiles are known to have antifungal properties. However, they have limited use because they diffuse rapidly in air. In this in vitro study, acetaldehyde was chosen as a prototype volatile in order to study the controlled release of antifungal volatiles from cyclodextrins (CD). The major postharvest pathogens Alternaria alternata, Botrytis cinerea, and Colletotrichum acutatum were exposed to the pure volatile for 7 days at 23 degrees C. Acetaldehyde was most effective against A. alternata, followed by C. acutatum, and B. cinerea, with 0.12, 0.56, and 1.72 microL/L in air being required to inhibit fungal growth, respectively, according to the bioassay developed. Second, the effectiveness of the new beta-CD-acetaldehyde release system was evaluated against A. alternata for 7 days at 23 degrees C. Sufficient volatile was released from 0.7 g of beta-CD-acetaldehyde to prevent fungal growth in vitro. 相似文献
967.
Cabedo N López-Gresa MP Primo J Ciavatta ML González-Mas MC 《Journal of agricultural and food chemistry》2007,55(17):6977-6983
Bioassay-guided fractionation of the organic extract derived from the terrestrial fungus Penicillium coalescens led to the isolation of the known mycotoxin (-)-botryodiplodin (1) and eight new structurally related analogues (2-9). The structures of the novel compounds were determined by MS and NMR studies, including 1D and 2D NMR. A likely biogenetic pathway from the aldehydic open form of 1 (C7 unit, U1) is proposed for these metabolites. Among all the isolated metabolites, only (-)-1 showed antifungal, antibacterial, and insecticidal activity. This latter activity appears to be a new property attributed to (-)-1. 相似文献
968.
Methven L Tsoukka M Oruna-Concha MJ Parker JK Mottram DS 《Journal of agricultural and food chemistry》2007,55(4):1427-1436
Volatile and nonvolatile compounds, which could contribute to flavor, were analyzed in salmon. One hundred twenty-three volatile compounds were identified in the headspace of two different samples of cooked salmon, including lipid-derived volatiles, Maillard-derived volatiles, sulfur volatiles, Strecker aldehydes, nitrogen heterocyclic compounds, terpenes, and trimethylamine. Significant differences between samples were found for 104 of the volatiles. Although the levels of free cysteine and methionine were low in the salmon, sulfur volatiles were formed in the cooked fish, demonstrating that there were sufficient sulfur amino acids present for their formation. Notable differences in sulfur compounds between the samples suggested that small changes in sulfur amino acids could be responsible. When this hypothesis was tested, salmon heated with cysteine had increased levels of many thiophenes, thiazoles, alicyclic sulfides, and nitrogen heterocycles. With the addition of methionine, levels of dimethyl sulfides, two alicyclic sulfides, pyrazines, some unsaturated aldehydes, and alcohols and 2-furanmethanethiol increased. The largest difference found among the nonvolatile (low molecular weight water-soluble) compounds was in inosine monophosphate. 相似文献
969.
Berti C Roncoroni L Falini ML Caramanico R Dolfini E Bardella MT Elli L Terrani C Forlani F 《Journal of agricultural and food chemistry》2007,55(6):2482-2488
The effects of chemical (acid-heating treatment) and enzymatic (microbial transglutaminase, TGase) modification (deamidation) of gluten proteins on their physicochemical and celiac disease-related properties were studied. Ammonia release, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and sample solubility analyses were employed to check the extent of gluten modification. Among different treatments achieved, the acid-heating treatment performed at 90 degrees C for 3 h induced gluten deamidation, paralleling an increase of gluten solubility without relevant proteolysis. Changes in the immunoreactivity of celiac IgA anti-gliadin antibodies (AGAs) to modified gluten proteins were detected by using a competitive indirect enzyme-linked immunosorbent assay method. Chemical deamidation by acid-heating treatment of gluten lowered IgA-AGA immunoreactivity. IgA-AGA immunoreactivity to gliadins was increased when they were submitted to TGase-catalyzed deamidation. The acid-heating treatment of gluten reduced its cytotoxic activity on human colon adenocarcinoma LoVo cell line. These results showed that chemical deamidation of gluten may be envisaged as a way to lower the potential risk for celiac people due to widespread use of gluten as a food additive. 相似文献
970.
Gentile C Tesoriere L Butera D Fazzari M Monastero M Allegra M Livrea MA 《Journal of agricultural and food chemistry》2007,55(3):643-648
Pistacia vera L. is the only species of Pistacia genus producing edible nuts. This paper investigates the antioxidant potential of a Sicilian variety of pistachio nut by chemical as well as biological assays and measured antioxidant vitamins and a number of antioxidant polyphenols in either the hydrophilic and/or the lipophilic nut extract. In accordance with the majority of foods, the total antioxidant activity, measured as a TAA test, was much higher (50-fold) in the hydrophilic than in the lipophilic extract. Substantial amounts of total phenols were measured. The hydrophilic extract inhibited dose-dependently both the metal-dependent and -independent lipid oxidation of bovine liver microsomes, and the Cu+2-induced oxidation of human low-density lipoprotein (LDL). Peroxyl radical-scavenging as well as chelating activity of nut components may be suggested to explain the observed inhibition patterns. Among tocopherols, gamma-tocopherol was the only vitamin E isomer found in the lipophilic extract that did not contain any carotenoid. Vitamin C was found only in a modest amount. The hydrophilic extract was a source of polyphenol compounds among which trans-resveratrol, proanthocyanidins, and a remarkable amount of the isoflavones daidzein and genistein, 3.68 and 3.40 mg per 100 g of edible nut, respectively, were evaluated. With the exception of isoflavones that appeared unmodified, the amounts of other bioactive molecules were remarkably reduced in the pistachio nut after roasting, and the total antioxidant activity decreased by about 60%. Collectively, our findings provide evidence that the Sicilian pistachio nut may be considered for its bioactive components and can effectively contribute to a healthy status. 相似文献