全文获取类型
收费全文 | 438篇 |
免费 | 23篇 |
专业分类
林业 | 37篇 |
农学 | 18篇 |
基础科学 | 1篇 |
157篇 | |
综合类 | 43篇 |
农作物 | 14篇 |
水产渔业 | 47篇 |
畜牧兽医 | 110篇 |
园艺 | 2篇 |
植物保护 | 32篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 17篇 |
2019年 | 10篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 9篇 |
2014年 | 5篇 |
2013年 | 39篇 |
2012年 | 15篇 |
2011年 | 33篇 |
2010年 | 14篇 |
2009年 | 13篇 |
2008年 | 23篇 |
2007年 | 31篇 |
2006年 | 22篇 |
2005年 | 29篇 |
2004年 | 24篇 |
2003年 | 19篇 |
2002年 | 24篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1998年 | 3篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1975年 | 3篇 |
1974年 | 5篇 |
1972年 | 2篇 |
1970年 | 4篇 |
1967年 | 4篇 |
1966年 | 2篇 |
1963年 | 2篇 |
1955年 | 2篇 |
1935年 | 1篇 |
1933年 | 1篇 |
1929年 | 1篇 |
1922年 | 1篇 |
排序方式: 共有461条查询结果,搜索用时 31 毫秒
71.
A benchtop baking method has been developed to predict the contribution of gluten functionality to overall flour performance for chemically leavened crackers. To identify a diagnostic cracker formula, the effects of leavening system (sodium bicarbonate, monocalcium phosphate, and ammonium bicarbonate), sugar concentration (%S), and total solvent (TS) on cracker‐baking performance were explored. From preliminary experiments to establish a production procedure, 10 min of dough‐mixing time, a cord‐weave baking mesh, and a 500°F oven temperature were selected. For the leavening system, increasing ammonium bicarbonate (ABC) level at constant sodium bicarbonate (soda) and monocalcium phosphate (MCP) levels resulted in increased cracker height. For the diagnostic formula, 1.25 g of soda, 1.25 g of MCP, and 1.25 g of ABC were selected, based on 100 g of flour. As the sugar concentration in the cracker formula, at constant total solvent (38 TS), decreased to <20%, the resulting cracker dough became softer, and the baked cracker exhibited an increased blistering tendency because of a too‐high formula water level. In contrast, a cracker dough formulated with >40% sugar concentration was too crumbly to handle and sheet. As the total solvent in the cracker formula increased at constant sugar concentration (≈23.7%S), the resulting dough became softer. A dough with 34 TS was too crumbly to handle, while doughs with 42 and 46 TS were too soft to handle and resulted in blistering. Therefore, 38 TS and 23.7%S were identified for the diagnostic formula. Crackers baked with a hard wheat flour, a soft wheat flour, and blends validated the utility of the developed method. 相似文献
72.
Jean‐Marie Séquaris Gregorio Guisado Maria Magarinos Carlos Moreno Peter Burauel Hans‐Dieter Narres Harry Vereecken 《植物养料与土壤学杂志》2010,173(5):699-705
According to recent conceptual models, the organic carbon (OC) of soils can be divided into OC fractions of increasing stability from labile free OC to resistant OC associated with the soil mineral phase. In this study, we present a method for quantifying two OC fractions based on soil aggregate–size fractionation and the N2 gas–adsorption method. For this purpose, we analyzed soil material of the plow layer of a Haplic Chernozem subjected to different fertilizer treatments (no fertilizer, mineral fertilizer, mineral and organic fertilizer). The total organic‐C concentration (TOC) and the clay content of the different size fractions were determined as well as the specific surface area (SSAmineral) and the sample pore volume after thermal oxidation (OC‐free). The TOC of the different soil‐aggregate fractions was linearly related to SSAmineral. Clay‐associated OC and nonassociated OC fractions of the different soil samples were quantified using two methods based on the OC surface loading at the clay fraction. The application of organic fertilizer increased the amount of nonassociated OC but hardly affected the concentration of clay‐associated OC. This finding agrees with previous studies on C dynamics in soils and indicates a finite capacity of soil materials to sequester OC. Even without any addition of organic fertilizer, the mineral phase of the analyzed soil material appears to be C‐saturated. 相似文献
73.
R. P. Oliver K. Rybak M. Shankar R. Loughman N. Harry P. S. Solomon 《Plant pathology》2008,57(3):527-532
Measuring disease resistance accurately and reproducibly is a key requirement for the introgression of partial resistance genes into breeding lines. Here, a qPCR protocol is used to measure fungal biomass, using the wheat- Stagonospora nodorum pathosystem as a model. Seven cultivars of differing reported resistance levels were used. Fungal biomass taken at 220°C thermal days after inoculation accurately predicts the final grain weight loss. It is concluded that a test based on qPCR methods is specific, quantitative, rapid and objective. Such tests could provide useful and economic tools in the development of robustly resistant crop cultivars. 相似文献
74.
Zhi-Qiang Chen Karl Lundén Bo Karlsson Ingrid Vos Åke Olson Sven-Olof Lundqvist Jan Stenlid Harry X. Wu María Rosario García Gil Malin Elfstrand 《European Journal of Forest Research》2018,137(4):517-525
Infections with Heterobasidion parviporum devalue the Norway spruce timber as the decayed wood does not meet the necessary quality requirements for sawing. To evaluate the incorporation of disease resistance in the Norway spruce breeding strategy, an inoculation experiment with H. parviporum on 2-year-old progenies of 466 open-pollinated families was conducted under greenhouse (nursery) conditions. Lesion length in the phloem (LL), fungal growth in sapwood (FG) and growth (D) were measured on an average of 10 seedlings for each family. The genetic variation and genetic correlations between both LL, FG and growth in the nursery trial and wood quality traits measured previously from 21-year old trees in two progeny trials, including solid-wood quality traits (wood density, and modulus of elasticity) and fiber properties traits (radial fiber width, tangential fiber width, fiber wall thickness, fiber coarseness, microfibril angle and fiber length). For both LL and FG, large coefficients of phenotypic variation (>?26%) and genetic variation (>?46%) were detected. Heritabilities of LL and FG were 0.33 and 0.42, respectively. We found no significant correlations between wood quality traits and growth in the field progeny trials with neither LL nor FG in the nursery trial. Our data suggest that the genetic gains may reach 41 and 52% from mass selection by LL and FG, respectively. Early selection for resistance to H. parviporum based on assessments of fungal spread in the sapwood in nursery material, FG, will not adversely affect growth and wood quality traits in late-age performance. 相似文献
75.
Winfried Schröder Stefan Nickel Simon Schönrock Roman Schmalfuß Werner Wosniok Michaela Meyer Harry Harmens Marina V. Frontasyeva Renate Alber Julia Aleksiayenak Lambe Barandovski Oleg Blum Alejo Carballeira Maria Dam Helena Danielsson Ludwig De Temmermann Anatoly M. Dunaev Barbara Godzik Katrin Hoydal Zvonka Jeran Gunilla Pihl Karlsson Pranvera Lazo Sebastien Leblond Jussi Lindroos Siiri Liiv Sigurður H. Magnússon Blanka Mankovska Encarnación Núñez-Olivera Juha Piispanen Jarmo Poikolainen Ion V. Popescu Flora Qarri Jesus Miguel Santamaria Mitja Skudnik Zdravko Špirić Trajce Stafilov Eiliv Steinnes Claudia Stihi Ivan Suchara Lotti Thöni Hilde Thelle Uggerud Harald G. Zechmeister 《Annals of Forest Science》2017,74(2):31
Key message
Moss surveys provide spatially dense data on environmental concentrations of heavy metals and nitrogen which, together with other biomonitoring and modelling data, can be used for indicating deposition to terrestrial ecosystems and related effects across time and areas of different spatial extension.Context
For enhancing the spatial resolution of measuring and mapping atmospheric deposition by technical devices and by modelling, moss is used complementarily as bio-monitor.Aims
This paper investigated whether nitrogen and heavy metal concentrations derived by biomonitoring of atmospheric deposition are statistically meaningful in terms of compliance with minimum sample size across several spatial levels (objective 1), whether this is also true in terms of geostatistical criteria such as spatial auto-correlation and, by this, estimated values for unsampled locations (objective 2) and whether moss indicates atmospheric deposition in a similar way as modelled deposition, tree foliage and natural surface soil at the European and country level, and whether they indicate site-specific variance due to canopy drip (objective 3).Methods
Data from modelling and biomonitoring atmospheric deposition were statistically analysed by means of minimum sample size calculation, by geostatistics as well as by bivariate correlation analyses and by multivariate correlation analyses using the Classification and Regression Tree approach and the Random Forests method.Results
It was found that the compliance of measurements with the minimum sample size varies by spatial scale and element measured. For unsampled locations, estimation could be derived. Statistically significant correlations between concentrations of heavy metals and nitrogen in moss and modelled atmospheric deposition, and concentrations in leaves, needles and soil were found. Significant influence of canopy drip on nitrogen concentration in moss was proven.Conclusion
Moss surveys should complement modelled atmospheric deposition data as well as other biomonitoring approaches and offer a great potential for various terrestrial monitoring programmes dealing with exposure and effects.76.
Ma H Forssell P Kylli P Lampi AM Buchert J Boer H Partanen R 《Journal of agricultural and food chemistry》2012,60(24):6223-6229
Sodium caseinate was modified by transglutaminase catalyzed cross-linking reaction prior to the emulsification process in order to study the effect of cross-linking on the oxidative stability of protein stabilized emulsions. The extent of the cross-linking catalyzed by different dosages of transglutaminase was investigated by following the ammonia production during the reaction and using SDS-PAGE gel. O/W emulsions prepared with the cross-linked and non-cross-linked sodium caseinates were stored for 30 days under the same conditions. Peroxide value measurement, oxygen consumption measurement, and headspace gas chromatography analysis were used to study the oxidative stability of the emulsions. The emulsion made of the cross-linked sodium caseinate showed an improved oxidative stability with reduced formation of fatty acid hydroperoxides and volatiles and a longer period of low rate oxygen consumption. The improving effect of transglutaminase catalyzed cross-linking could be most likely attributed to the enhanced physical stability of the interfacial protein layer against competitive adsorption by oil oxidation products. 相似文献
77.
Atmospheric pollution is known to induce corrosion effects on various materials. For Greece, stone deterioration could emerge severe costs in the case of damaging cultural monuments. This work aims to investigate the corrosion process on materials of archaeological importance (marble, limestone, and sandstone) in the Greater Athens Area (GAA) by using sophisticated geoanalytical methods together with dose?Cresponse functions for selected materials, in order to derive corrosion maps for GAA in the period 2000?C2009. Also, a corrosion trend analysis is performed, which can be a very helpful tool for the prediction of potential risks to monuments of cultural heritage due to atmospheric pollution. The corrosion effects on the selected materials are generally weak. Nevertheless, increasing corrosion trends are found in the eastern regions of GAA for all sheltered materials and in the northern parts of GAA for unsheltered marble. The technique is finally applied to 12 locations in GAA, which include some of the most important archaeological monuments of Athens, and provides comprehensive results for the estimation of the impact of atmospheric corrosion on the structural materials of these archaeological sites. 相似文献
78.
Ma H Forssell P Partanen R Buchert J Boer H 《Journal of agricultural and food chemistry》2011,59(24):13246-13253
Whey protein isolate was modified by ethylene diamine in order to shift its isoelectric point to an alkaline pH. The extent of the modification was studied using SDS-PAGE and MALDI-TOF mass spectrometry. The modified whey proteins were used as an emulsifier to stabilize oil-in-water emulsions at acidic and neutral pH ranges, and their emulsifying properties were compared with that of the unmodified whey proteins and with the previously studied ethylene diamine modified sodium caseinate. The emulsifying activity of the modified whey proteins was similar to that of the unmodified ones, but the stability of an emulsion at pH 5 was significantly improved after the modification. Charge and coverage of droplet surface and the displacement of the interfacial proteins by surfactant Tween 20 were further studied as a function of pH. As compared with the unmodified whey proteins, the modified ones were proven to cover the interface more efficiently with extensive surface charge at pH 5, although the interfacial layer was less resistant to the surfactant displacement. 相似文献
79.
Narváez-Cuenca CE Kuijpers TF Vincken JP de Waard P Gruppen H 《Journal of agricultural and food chemistry》2011,59(18):10247-10255
The effect of sodium hydrogen sulfite (S), used as antibrowning agent, on the phenolic profile of potato extracts was investigated. This extract was compared to one obtained in the presence of ascorbic acid (A). In the presence of A, two major compounds were obtained, 5-O-caffeoylquinic acid (5-CQA) and 4-O-caffeoyl quinic acid. With S, their 2'-sulfo-adducts were found instead, the structures of which were confirmed by nuclear magnetic resonance spectroscopy and mass spectrometry. Also, for minor caffeoyl derivatives and quercetin glycosides, the corresponding sulfo-adducts were observed. Feruloyl and sinapoyl derivatives were not chemically affected by the presence of S. Polyphenol oxidase (PPO) was thought to be responsible for the formation of the sulfo-adducts. This was confirmed by preparing 2'-sulfo-5-O-caffeoyl quinic acid in a model system using 5-CQA, sodium hydrogen sulfite, and PPO. This sulfo-adduct exhibited a small bathochromic shift (λmax 329 nm) as compared to 5-CQA (λmax 325 nm) and a strong hypochromic shift with an extinction coefficient of 9357±395 M(-1) cm(-1) as compared to 18494±196 M(-1) cm(-1), respectively. The results suggest that whenever S is used as an antibrowning agent, the O-quinone formed with PPO reacts with S to produce sulfo-O-diphenol, which does not participate in browning reactions. 相似文献
80.
The course of the Maillard reaction between α-lactalbumin and various mono- and oligosaccharides in the solid state was studied using UPLC-ESI-TOF-MS. Individual reaction products were monitored for their degree of substitution per protein molecule (DSP). The Maillard reaction rate depended on the saccharide type and decreased when the saccharide size increased. Conjugation with charged saccharides was hindered when a specific average DSP was reached, probably resulting from electrostatic repulsion. The DSP varied between 0 and 15, and the standard deviation of the average DSP, which is a measure for product dispersity, increased to 1.9. Similar experiments were performed with a dipeptide. Relative reaction rates in these experiments were 1 for glucose, 0.28 for maltose, and 0.16 for maltotriose. Comparison of the results obtained using α-lactalbumin and the dipeptide made clear that the Maillard reaction rate is determined by a number of factors, including saccharide reactivity and lysine accessibility. 相似文献