全文获取类型
收费全文 | 1110篇 |
免费 | 70篇 |
专业分类
林业 | 94篇 |
农学 | 36篇 |
321篇 | |
综合类 | 27篇 |
农作物 | 88篇 |
水产渔业 | 128篇 |
畜牧兽医 | 374篇 |
园艺 | 22篇 |
植物保护 | 90篇 |
出版年
2024年 | 1篇 |
2023年 | 15篇 |
2022年 | 12篇 |
2021年 | 50篇 |
2020年 | 49篇 |
2019年 | 52篇 |
2018年 | 49篇 |
2017年 | 53篇 |
2016年 | 57篇 |
2015年 | 35篇 |
2014年 | 50篇 |
2013年 | 58篇 |
2012年 | 109篇 |
2011年 | 98篇 |
2010年 | 57篇 |
2009年 | 44篇 |
2008年 | 73篇 |
2007年 | 70篇 |
2006年 | 55篇 |
2005年 | 44篇 |
2004年 | 32篇 |
2003年 | 35篇 |
2002年 | 34篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1983年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有1180条查询结果,搜索用时 31 毫秒
101.
Blanco PG Tórtora M Rodríguez R Arias DO Gobello C 《Veterinary journal (London, England : 1997)》2011,190(1):154-159
The aim of this study was to describe changes in cardiac morphology, systolic function and some peripheral hemodynamic parameters during normal pregnancy in dogs. Twenty healthy bitches, 10 pregnant (PG) and 10 non-pregnant controls (CG), were evaluated every 10 days using echocardiography from day 0 of the estrus cycle to parturition or to day 65 for the PG and CG groups, respectively. Systolic blood pressure (SBP) and uterine artery resistance index (RI) were also assessed. Throughout the study, the shortening fraction and cardiac output increased up to 30% vs. 5% (P<0.01) and 45% vs. 2% (P<0.01) in the PG and CG groups, respectively. In contrast, SBP and RI diminished up to 20% vs. 1% (P<0.01) and 29% vs. 0% (P<0.01) in the PG and CG groups, respectively. In conclusion, a decrease in afterload, an increase in cardiac output and cardiac hypertrophy appear to be the result of the hemodynamic modifications occurring during pregnancy in dogs. 相似文献
102.
BACKGROUND: The tomato leafminer (Tuta absoluta Povolny) has rapidly colonised the whole Mediterranean and South‐Atlantic coasts of Spain, and it has become a key problem in both outdoor and greenhouse crops. New control methods compatible with biological control are required, and mating disruption appears to be a perfect method in current agriculture, as it is an environmentally friendly and residue‐free technique. IPM packages tested have included the use of pheromones to detect populations, but there has not been much previous research on mating disruption of T. absoluta. In this work, pheromone doses varying from 10 to 40 g ha?1, emitted at a constant rate over 4 months, were tested in greenhouses with different levels of containment in order to evaluate the efficacy of mating disruption on T. absoluta. RESULTS: Trials on containment level revealed that the flight of T. absoluta was satisfactorily disrupted with an initial pheromone dose of 30 g ha?1, and levels of damage did not significantly differ from those in reference plots with insecticide treatments. Later efficacy trials confirmed previous experiences, and release studies showed that control of damage and flight disruption were taking place when releasing at least 85 mg pheromone per ha per day. CONCLUSION: Effective control using pheromone application against T. absoluta can be achieved, in greenhouses with high containment levels, for 4 months, with initial doses of 30 g ha?1. Further research must be conducted in order to evaluate the prospect of outdoor application of mating disruption systems. Copyright © 2011 Society of Chemical Industry 相似文献
103.
Vallejo F Tomas-Barberan F Garcia-Viguera C 《Journal of agricultural and food chemistry》2003,51(10):3029-3034
Total aliphatic and indole glucosinolates, phenolic compounds (flavonoids and hydroxycinnamoyl derivatives), and vitamin C contents were evaluated in freshly harvested broccoli (Brassica oleracea L., var. italica, cv. Marathon) inflorescences. These were film-wrapped and stored for 7 days at 1 degrees C to simulate a maximum period of commercial transport and distribution. After cold storage, inflorescences were kept for 3 days at 15 degrees C to simulate a retail sale period. For wrapping, low-density polyethylene (LDPE) of 11 microm thickness was used. Gas composition was about 17% O(2) and 2% CO(2) during cold storage and about 16% O(2) and 3-4% CO(2) during shelf life within packages. The predominant glucosinolates were 4-methylsulfinylbutyl-glucosinolate (glucoraphanin), 3-indolylmethyl-glucosinolate (glucobrassicin), and 1-methoxy-3-indolylmethyl-glucosinolate (neoglucobrassicin). The predominant hydroxycinnamoyl derivatives were identified as 1,2,2'-trisinapoylgentiobiose, 1,2-diferuloylgentiobiose, 1,2'-disinapoyl-2-feruloylgentiobiose, and 3-O-caffeoyl-quinic (neochlorogenic acid). Results showed major losses at the end of both periods, in comparison with broccoli at harvest. Thus, the respective losses, at the end of cold storage and retail periods, were 71-80% of total glucosinolates, 62-59% of total flavonoids, 51-44% of sinapic acid derivatives, and 73-74% caffeoyl-quinic acid derivatives. Slight differences in all compound concentrations between storage and retail sale periods were detected. Distribution and retail periods had minimal effects on vitamin C. Weight loss was monitored at the end of both periods. 相似文献
104.
Racchi M Daglia M Lanni C Papetti A Govoni S Gazzani G 《Journal of agricultural and food chemistry》2002,50(5):1272-1277
The antiradical activity of water-soluble components contained in mushrooms (Psalliota campestris), onions (Allium cepa), white cabbage (Brassica oleracea var. alba), and yellow bell peppers (Capsicum annuum) against hydroxyl radicals was tested in a chemical and biological system. The vegetable juices were obtained by centrifugation of a vegetable homogenate processed at 2 degrees C or heated at 102 degrees C. The chemical system consisted of a buffered reaction mixture composed of Fe(III)-EDTA, 2-deoxy-D-ribose, ascorbic acid, and H(2)O(2) generating the hydroxyl radical. The antiradical activity was expressed as an inhibition of deoxyribose degradation. The biological system consisted of IMR32 neuroblastoma cells exposed to H(2)O(2) in the presence or absence of the vegetable juices. Cells were pretreated for either 24 h or 1 h with the vegetable juices, and reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was used as a cell viability assay. All vegetable juices inhibited the degradation of deoxyribose and increased the viability of H(2)O(2) treated cells. Raw mushroom juice proved to be the most active in both cases. Boiling significantly affected the activity of mushroom juice, but did not change significantly the effect on onions and yellow bell peppers, and partially increased the activity of white cabbage juice. Mushroom antiradical activity was also confirmed by a cytofluorimetric analysis. 相似文献
105.
Martínez-Villaluenga C Frias J Gulewicz K Vidal-Valverde C 《Journal of agricultural and food chemistry》2004,52(23):6920-6922
Improvement of a previously described method of purification of alpha-galactosides, members of the raffinose family of oligosaccharides (RFOs), has been developed for lupins. The considerable amount of sucrose present in the RFO preparations obtained by the previous method has been removed by modifying the purification stage on diatomaceous earth and charcoal. The present method allows for the preparation of high-purity RFOs containing approximately 99.4% of RFOs in the form of a white fine powder, which provides new perspectives for the production of pure alpha-galactoside preparations for their use as prebiotics in functional foods. 相似文献
106.
Roura E Andrés-Lacueva C Jáuregui O Badia E Estruch R Izquierdo-Pulido M Lamuela-Raventós RM 《Journal of agricultural and food chemistry》2005,53(16):6190-6194
A rapid liquid chromatography electrospray ionization tandem mass spectrometry with negative ion detection method was developed and validated to determine cocoa flavonoid metabolites in human plasma and urine after the intake of a standard portion of a cocoa beverage. A chromatographic run time of only 9 min provided clear separation of all metabolites and internal standards. Samples were analyzed in a product-ion scan of m/z 289, 369, and 465 to identify the metabolites and in multiple reaction monitoring acquisition mode to quantify (-)-epicatechin ((-)-Ec) (289/ 245), (-)-epicatechin-glucuronide ((-)-EcG) (465/289), and (-)-epicatechin-sulfate ((-)-EcS) (369/289). One (-)-Ec-G and three (-)-Ec-S were identified and confirmed in urine as the major metabolites, and one (-)-Ec-G was the only metabolite present in plasma volunteers (n = 5) at a mean concentration of 625.7 +/- 198.3 nmol/L at 2 h after consumption of a cocoa beverage containing 54.4 mg of (-)-Ec. 相似文献
107.
Faleiro L Miguel G Gomes S Costa L Venâncio F Teixeira A Figueiredo AC Barroso JG Pedro LG 《Journal of agricultural and food chemistry》2005,53(21):8162-8168
Antilisterial activities of Thymbra capitata and Origanum vulgare essential oils were tested against 41 strains of Listeria monocytogenes. The oil of T. capitata was mainly constituted by one component, carvacrol (79%), whereas for O. vulgare three components constituted 70% of the oil, namely, thymol (33%), gamma-terpinene (26%), and p-cymene (11%). T. capitata essential oil had a significantly higher antilisterial activity in comparison to O. vulgare oil and chloramphenicol. No significant differences in L. monocytogenes susceptibilities to the essential oils tested were registered. The minimum inhibitory concentration values of T. capitata essential oil and of carvacrol were quite similar, ranging between 0.05 and 0.2 microL/mL. Antioxidant activity was also tested, the essential oil of T. capitata showing significantly higher antioxidant activity than that of O. vulgare. Use of T. capitata and O. vulgare essential oils can constitute a powerful tool in the control of L. monocytogenes in food and other industries. 相似文献
108.
Abad A Agulló C Cuñat AC Jiménez R Vilanova C 《Journal of agricultural and food chemistry》2004,52(15):4675-4683
Seventeen phenyl-fluorinated analogues of thidiazuron [N-phenyl-N'-(1,2,3-thiadiazol-5-yl)urea, TDZ] have been prepared and characterized. The effects of each fluorinated urea on growth and quality of kiwifruits (Actinidia deliciosa) were evaluated by comparison with untreated (control) and TDZ-treated fruits. The results obtained showed a clear dependence of the growth-promoting activity of these fluorinated ureas on the pattern and degree of fluorine substitution in the phenyl ring. The most effective for promoting fruit growth was N-(2,3,5,6-tetrafluorophenyl)-N'-(1',2',3'-thiadiazol-5'-yl)urea at 25 ppm (at harvest, treated fruits were 58% heavier than untreated ones) followed by N-(3,5-difluorophenyl)-N'-(1',2',3'-thiadiazol-5'-yl)urea at 10 ppm (50%). Comparatively, TDZ-treated fruits were 31% (10 ppm) and 38% (25 ppm) heavier than untreated ones. The results also indicate that the effects of the more active phenyl-fluorinated ureas on some standard quality parameters of fruits, for example, percent of fruit dry matter content, soluble solids contents, total titratable acids, shape, and internal structure, are similar to those of TDZ. Quantitative structure-activity relationships have been derived for the fruit growth promoting activity of the phenyl-fluorinated analogues of TDZ. 相似文献
109.
110.
Tovar L Salafranca J Sánchez C Nerín C 《Journal of agricultural and food chemistry》2005,53(13):5270-5275
Both specific and overall migration tests have been applied to new experimental food packaging-active plastic films with antioxidant properties, including in its composition a natural rosemary extract. Determination of volatile and semivolatile compounds migrating from plastic to the four established simulants showed that both specific and overall migration was very low. The results obtained gave values 20 times lower than the established limits in the worst case. So, from the point of view of health risk, the new active packaging can be considered as safe. Analytical procedure used provided the necessary information about the migration behavior, with good analytical characteristics and detection limits in the sub mug kg(-1) range. Besides, no significant difference was found between laboratory and factory-made samples, which is an important issue for industrial production, the next step in the development of the new antioxidant active film. 相似文献