全文获取类型
收费全文 | 114篇 |
免费 | 7篇 |
专业分类
林业 | 4篇 |
农学 | 4篇 |
基础科学 | 1篇 |
28篇 | |
综合类 | 10篇 |
农作物 | 4篇 |
水产渔业 | 8篇 |
畜牧兽医 | 46篇 |
园艺 | 2篇 |
植物保护 | 14篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 12篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 9篇 |
2012年 | 6篇 |
2011年 | 13篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 11篇 |
2007年 | 10篇 |
2006年 | 5篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 1篇 |
1995年 | 1篇 |
1984年 | 1篇 |
1981年 | 2篇 |
1964年 | 1篇 |
排序方式: 共有121条查询结果,搜索用时 13 毫秒
91.
Marta Simone Mendonça Freitas Pedro Henrique Monnerat Ivo José Curcino Vieira 《Journal of plant nutrition》2013,36(10):1844-1854
ABSTRACT A greenhouse experiment was performed to evaluate macronutrients and boron deficiencies on vitexin bioproduction by sweet passion fruit leaves. Sand irrigated with nutrient solution was used as substrate in a complete randomized design, with eight treatments: 1) complete, 2) nitrogen-deficient(-N), 3) phosphorus-deficient(-P), 4) potassium-deficient(-K), 5) calcium-deficient(-Ca), 6) magnesium-deficient(-Mg), 7) sulfur-deficient(-S), and 8) boron-deficient(-B). After thirty days, the fourth fully expanded leaves were harvested. Under deficiency treatments, leaf dry matter concentrations of N, P, K, Ca, Mg, S, and B were 52, 53, 62, 76, 69, 31, and 80% lower than in complete treatment, respectively. Nitrogen, P, and K deficiency increased vitexin leaf concentration by 46, 16, and 18%, although Ca and B deficiencies decreased vitexin concentration by 22 and 33%, respectively, when compared to complete treatment. Magnesium and S deficiencies had no significant effect on vitexin concentration. In complete treatment, the concentration of nutrients and vitexin, in leaf dry matter were: 43.4 g kg? 1 of N, 2.47 g kg? 1 of P, 27.4 g kg? 1 of K, 15.6 g kg? 1 of Ca, 3.8 g kg? 1 of Mg, 5.28 g kg? 1 of S, 64 mg kg? 1 of B, and 5.57 mg kg? 1 of vitexin. 相似文献
92.
Silva KR Raimundo IM Gimenez IF Alves OL 《Journal of agricultural and food chemistry》2006,54(23):8697-8701
A method for the determination of free and total sulfur dioxide in wines, based on the use of an optical sensor that employs a dichlorobis(diphenylphosphino)methane dipalladium I complex [Pd(2)(dppm)(2)Cl(2)] immobilized in a PVC membrane plasticized with o-nitrophenyloctylether (o-NPOE) is described. A sensing membrane [4.2% Pd(2)(dppm)(2)Cl(2), 20.8% PVC, and 75% o-NPOE] was adapted to the tip of a bifurcated optical fiber bundle to perform reflectance measurements at 550 nm. The detection system consisted of two cells (40 mL), which hold the sample solution (plus reagents) and the optical sensor, respectively. For the determination of free SO(2), a wine sample was mixed with H(2)SO(4) solution in the sample cell, into which N(2) was bubbled, providing mixing of the solutions and conducting the SO(2) formed toward the detection cell. For determination of total SO(2), a KOH solution was mixed with the wine in the sample cell. Afterward, an H(2)SO(4) solution was added to the cell, and then N(2) was bubbled to conclude the measurement. Linear responses up to 50 and 150 mg L(-1) were obtained for free and total SO(2), with detection limits of 0.37 and 0.70 mg L(-1), respectively. The repeatability of the method was evaluated by carrying out 10 measurements using a single wine sample, providing relative standard deviation values of 2.2 and 2.5% for free and total SO(2), respectively. The sensing membrane prepared from 10 muL of the cocktail solution lasted for 80 measurements, whereas those prepared from 200 muL can be used for 250 measurements. The method was applied to free and total SO(2) determination in wines, and the results did not show significant difference from those obtained with the Ripper reference method at a confidence level of 95%. 相似文献
93.
Rodinei F. Pegoraro Ivo R. Silva Roberto F. Novais Eduardo S. Mendona Victor Hugo Alvarez Flancer N. Nunes Frederico M. Fonseca Thomas J. Smyth 《植物养料与土壤学杂志》2005,168(3):334-340
Low‐molecular‐weight organic acids with one or more carboxylic groups are ubiquitous. In soils, they can originate from leaching of plants, litter decomposition, plant‐roots exudation, and microbial activity. Their presence in the soil may favor the formation of soluble organo‐metallic complexes that improve the transport of Zn, Cu, Fe, and Mn to plant‐root surfaces via diffusion. The current study sought to determine if some of the organic acids (OA) in soils and a cover‐crop residue influence the diffusive flux (DF) of Zn, Cu, Mn, and Fe. Two OA were added to two Oxisols (Typic Haplustox): a clayey Dark Red Latosol (DRL) and a sandy‐loam Red Yellow Latosol (RYL). Acetic and citric acid were added to achieve concentrations of 0, 250, 500, 1000, and 2000 mmol (m3 soil)–1. The effect of adding plant material (pearl millet) on the soil DF of the cationic micronutrients was also determined. Soil diffusive flux was evaluated by incubating positively charged and negatively charged exchange‐resin membranes with the soil in PVC diffusion chambers for 15 d. Desorption of Zn, Cu, Fe, Mn, and OA from the resins was performed with 0.5 mol l–1 HCl. The results demonstrated that the DF of the cationic micronutrients increased with the addition of organic acid. The DF of Zn and Mn occurred mostly towards the cationic resin, whereas the diffusive flux of Cu and Fe occurred mostly towards the anionic resin. Apparently, the dissolution of oxides and/or complexation of micronutrients adsorbed to the solid phase or in the soil solution contributed to the obtained results. Citric acid was more efficient than acetic acid in maintaining a larger DF value for Zn, Cu, and Fe. The addition of millet plant material to the soil increased the DF in the following order: Mn > Cu > Fe > Zn; Mn moved towards the cationic resin, and the other micronutrients moved towards the anionic resin. These findings suggest that organic compounds play an important role in the short‐distance transport of cationic micronutrients in highly weathered soils. 相似文献
94.
A new tetramic acid glycoside, aurantoside K, was isolated from a marine sponge belonging to the genus Melophlus. The structure of the compound was elucidated on the basis of spectroscopic analysis (1H NMR, 1H-1H COSY, HSQC, and HMBC, as well as high-resolution ESILCMS). Aurantoside K did not show any significant activity in antimalarial, antibacterial, or HCT-116 cytotoxicity assays, but exhibited a wide spectrum of antifungal activity against wild type Candida albicans, amphotericin-resistant C. albicans, Cryptococcus neoformans, Aspergillus niger, Penicillium sp., Rhizopus sporangia and Sordaria sp. 相似文献
95.
Tomáš Grygar Ivo Světlík Lenka Lisá Leona Koptíková Aleš Bajer David S. Wray Vojtěch Ettler Martin Mihaljevič Tereza Nováková Magdaléna Koubová Jan Novák Zdeněk Máčka Mirek Smetana 《CATENA》2010
The floodplain of the Morava River in Strá?nické Pomoraví, south-east Moravia, Czech Republic contains a very valuable record of regional environmental change, which goes back to several thousand years. Its interpretation has been limited by poor stratigraphic correlation and dating of the sediments. We present a geochemical solution to this challenge. We studied 8 outcrops of floodplain deposits from 4 localities along a 6 km long part of the current meander belt of the Morava River in Strá?nické Pomoraví using geochemical proxy analyses, magnetic susceptibility measurements, 14C dating of wood remnants, and sediment micromorphology. The proxy methods are based on elemental analysis (EDXRF) and analysis of the cation exchange capacity of clay minerals; granulometric analyses provided the basis for lithological and facies assignment of the sediments. Our geochemical and mineralogical interpretations have further been tested by microstratigraphically studying the optical properties of the fine fraction. Horizons older than about 3 centuries were 14C dated using wood remnants and the age of deposits from the last century was determined on the base of several proxies reflecting their industrial contamination by heavy metals and magnetic particles. The mean depositional rate over the period from about 1000 to about 1900 AD ranged from 0.2 to 0.6 mm y− 1, depending on the sedimentary facies. The coeval lithological change in the majority of the studied sections indicated a change of the meander belt structure at between ~ 1200 AD and ~ 1600 AD probably as a consequence of changes of channel structure. The alluvial deposition in the 20th century was strongly affected by the river regulation. 相似文献
96.
Ivo Baur Léa Tabin McLoyd Banda Daniel Chiumia Markus Lips 《Tropical animal health and production》2017,49(2):251-258
Milk production in Malawi is stagnating while steadily increasing in neighboring countries. We performed a literature review to identify factors negatively affecting milk production in Malawi and propose potential solutions to overcome the particular constraints. We structured the analysis along the value chain with three major components: upstream providers, on-farm production, and downstream providers. It is shown that the literature strongly focuses on on-farm constraints and most prominently on animal health, breed choice, and milk yield. The literature research did not reveal any reasons specific to Malawi that would hinder an increase in milk production as experienced in neighboring countries. We suggest a focus on crossbreeds accompanied by local breeding programs, which would reduce dependence on imported semen and strengthen the currently unreliable artificial insemination services. In addition, crossbreeds may be better suited than pure breeds for current feeding practices and climate conditions and thus come close to reaching their genetic potential. We conclude that cost advantages of crossbreeds clearly compensate for the lower revenues compared with exotic breeds such as Holstein-Friesian or Jersey. 相似文献
97.
GUO Kai-jun LIU Feng-hua LU Lin Biagini Davide Lazzaroni Carla Zoccarato Ivo 《中国农业科学(英文版)》2010,9(5):721-728
The aims of the study were to evaluate productive performances and environmental impact of double-muscled Piemontese culled cows. In two trials, 39 Piemontese culled cows aged from 46 to 176 mon were fattened using diets commonly applied in farm conditions. The animals were weighed at the beginning and end of the trials. Concentrate and hay intake were recorded daily. After slaughtering, meat, fat and bone yields were recorded and dressing percentage was calculated. The backward linear regression model was employed for statistical analysis. Results showed average body weight (ABW) of cows as (556.97± 55.99) kg and relatively low dry matter intake (DMI) [(9.17± 0.35) kg d^-1] during the fattening period. The ratio between DMI and ABW, i.e., ratio between intake and weight (RIW), (1.66±0.18)% was negatively influenced by initial body weight (IBW) and duration of finishing period (D), but age had no effect on RIW. Average daily gain (ADG) was relatively low [(0.55 ±0.21) kg d^-1, and was negatively correlated with IBW and D, which implied that lower IBW and shorter D could have higher ADG and vice versa. The dressing percentage (DP) was (59.80± 1.83)% and the carcass red meat yield (MY) was (75.17±3.10)%. Nevertheless, N efficiency was very low [(4.35 ± 1.76)%], which must be considered in relation to environmental protection so both animal requirements and a well balanced diet need more attention. In conclusion when Piemontese cows will be culled and fattened, IBW and D should be considered carefully in order to get a reasonable ADG and N efficiency to guarantee productive benefits and environmental protection at the same time. 相似文献
98.
99.
Stepanova H Pavlova B Stromerova N Ondrackova P Stejskal K Slana I Zdrahal Z Pavlik I Faldyna M 《Veterinary microbiology》2012,159(3-4):343-350
Mycobacterium avium subsp. avium (MAA) and Mycobacterium avium subsp. hominissuis (MAH) are the most common mycobacterial species isolated from granulomatous lesions in swine in countries with controlled bovine tuberculosis. This study is focused on the immunological aspect of MAA and MAH infection in pigs. We detected induction of humoral and cell-mediated immunity in experimentally infected pigs. Specific antibodies were analyzed in serum by ELISA and the IFN-γ release assay was used for evaluation of cell-mediated immunity. While MAA induced a significant increase of both types of immune responses, MAH-infected pigs had an unvarying level of specific antibodies and showed low cell-mediated immunity with high individual variability. The subsequent in vitro experiment confirmed the lower immunogenicity of the MAH strain in comparison to MAA. MAH-infected porcine monocyte-derived macrophages showed a weaker induction of pro-inflammatory mediators in comparison to MAA, which included mRNA for IL-1β, TNF-α, IL-23p19, IL-18 and chemokines CCL-3, CCL-5, CXCL-8 and CXCL-10. Additionally, qualitative proteomic analysis revealed 28 proteins exclusively in MAA and 7 proteins unique to MAH. In conclusion, closely related M. avium subspecies MAA and MAH showed different capacities to stimulate the porcine immune system. From a diagnostic point of view, the IFN-γ release assay showed higher sensitivity than the detection of specific antibodies by ELISA and seems to be an effective tool for discrimination of MAA-infected pigs. In the case of MAH infection, the IFN-γ release assay could fail because of the low immunogenic capacity of the MAH strain. 相似文献