全文获取类型
收费全文 | 578篇 |
免费 | 35篇 |
专业分类
林业 | 93篇 |
农学 | 19篇 |
基础科学 | 6篇 |
117篇 | |
综合类 | 66篇 |
农作物 | 36篇 |
水产渔业 | 35篇 |
畜牧兽医 | 166篇 |
园艺 | 29篇 |
植物保护 | 46篇 |
出版年
2024年 | 1篇 |
2023年 | 12篇 |
2022年 | 21篇 |
2021年 | 30篇 |
2020年 | 26篇 |
2019年 | 12篇 |
2018年 | 23篇 |
2017年 | 25篇 |
2016年 | 15篇 |
2015年 | 27篇 |
2014年 | 32篇 |
2013年 | 34篇 |
2012年 | 44篇 |
2011年 | 59篇 |
2010年 | 22篇 |
2009年 | 18篇 |
2008年 | 38篇 |
2007年 | 27篇 |
2006年 | 27篇 |
2005年 | 29篇 |
2004年 | 28篇 |
2003年 | 15篇 |
2002年 | 19篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1980年 | 1篇 |
1959年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有613条查询结果,搜索用时 15 毫秒
131.
Guillaume Lenoir Loïc Flatres-Grall Nicolas C Friggens Ingrid David 《Journal of animal science》2022,100(5)
The objective was to determine operational proxies for robustness based on data collected routinely on farm that allow phenotyping of these traits in fattening pigs, and to estimate their genetic parameters. A total of 7,256 pigs, from two Piétrain paternal lines (Pie and Pie NN), were tested at the AXIOM boar testing station (Azay-sur-Indre, France) from 2019 to 2021. During the fattening period (from 75 to 150 d of age), individual performance indicators were recorded (growth, backfat, loin depth, feed intake, and feed conversion ratio [FCR]) together with indicators such as insufficient growth, observable defect, symptoms of diseases, and antibiotic and anti-inflammatory injections. These indicators were combined into three categorical robustness scores: R1, R2, and R3. Genetic parameters were estimated using an animal linear model. The robustness score R2 (selectable or not selectable animal) that combined information from status at testing and mortality had the highest heritability estimates of 0.08 ± 0.03 for Pie NN line and a value of 0.09 ± 0.02 for Pie line, compared with traits R1 and R3. The score R3 that combines information from the score R2 with antibiotic and anti-inflammatory injections presented slightly lower heritability estimates (0.05 ± 0.02 to 0.07 ± 0.03). Genetic correlations between R2 and R3 were high and favorable (0.93 ± 0.04 to 0.95 ± 0.03) and R2 and R3 can be considered identical with regard to the confidence interval. These two robustness scores were also highly and favorably genetically correlated with initial body weight and average daily gain, and unfavorably correlated with daily feed intake (ranging from 0.73 ± 0.06 to 0.90 ± 0.08). Estimates of genetic correlations of R2 and R3 with backfat depth and raw FCR (not standardized between starting and finishing weights) were moderate and unfavorable (0.20 ± 0.13 to 0.46 ± 0.20). A part of these genetic correlations, that are of low precision due to the number of data available, have to be confirmed on larger datasets. The results showed the interest of using routine phenotypes collected on farm to build simple robustness indicators that can be applied in breeding. 相似文献
132.
Paraphoma chlamydocopiosa sp. nov. and Paraphoma pye sp. nov., two new species associated with leaf and crown infection of pyrethrum 下载免费PDF全文
A. Moslemi P. K. Ades P. W. Crous T. Groom J. B. Scott M. E. Nicolas P. W. J. Taylor 《Plant pathology》2018,67(1):124-135
Two new pathogens of pyrethrum, described as Paraphoma chlamydocopiosa and Paraphoma pye, isolated from necrotic leaf lesions on pyrethrum plants in northern Tasmania, Australia, were identified using morphological characters, phylogenetic analysis of the internal transcribed spacer (ITS), elongation factor 1‐α (EF1‐α) and β‐tubulin (TUB) genes, and pathogenicity bioassays. Bootstrap support in the combined and individual gene region phylogenetic trees supported the two species that were significantly different from the closely related P. chrysanthemicola and P. vinacea. Morphological characteristics also supported the two new species, with conidia of P. chlamydocopiosa being considerably longer and wider than either P. chrysanthemicola or P. vinacea, and P. pye being distinct in forming bilocular pycnidia. Glasshouse pathogenicity tests based on root dip inoculation resulted in P. chlamydocopiosa and P. pye infecting the crown and upper root tissues of pyrethrum plants, and significant reduction in biomass 2 months after inoculation. Both of these Paraphoma species caused leaf lesions during in vitro and in vivo bioassays 2 weeks after foliar spray inoculation. Although P. chlamydocopiosa and P. pye were shown to be crown rot pathogens, they were also commonly isolated from leaves of diseased plants in pyrethrum fields of northern Tasmania. 相似文献
133.
Nomie De San Nicolas Aromal Asokan Rafael D. Rosa Sbastien N. Voisin Marie-Agns Travers Gustavo Rocha Luc Dantan Yann Dorant Guillaume Mitta Bruno Petton Guillaume M. Charrire Jean-Michel Escoubas Viviane Boulo Juliette Pouzadoux Herv Meudal Karine Loth Vincent Aucagne Agns F. Delmas Philippe Bulet Caroline Montagnani Delphine Destoumieux-Garzn 《Marine drugs》2022,20(12)
Big defensins are two-domain antimicrobial peptides (AMPs) that have highly diversified in mollusks. Cg-BigDefs are expressed by immune cells in the oyster Crassostrea gigas, and their expression is dampened during the Pacific Oyster Mortality Syndrome (POMS), which evolves toward fatal bacteremia. We evaluated whether Cg-BigDefs contribute to the control of oyster-associated microbial communities. Two Cg-BigDefs that are representative of molecular diversity within the peptide family, namely Cg-BigDef1 and Cg-BigDef5, were characterized by gene cloning and synthesized by solid-phase peptide synthesis and native chemical ligation. Synthetic peptides were tested for antibacterial activity against a collection of culturable bacteria belonging to the oyster microbiota, characterized by 16S sequencing and MALDI Biotyping. We first tested the potential of Cg-BigDefs to control the oyster microbiota by injecting synthetic Cg-BigDef1 into oyster tissues and analyzing microbiota dynamics over 24 h by 16S metabarcoding. Cg-BigDef1 induced a significant shift in oyster microbiota β-diversity after 6 h and 24 h, prompting us to investigate antimicrobial activities in vitro against members of the oyster microbiota. Both Cg-BigDef1 and Cg-BigDef5 were active at a high salt concentration (400 mM NaCl) and showed broad spectra of activity against bacteria associated with C. gigas pathologies. Antimicrobial specificity was observed for both molecules at an intra- and inter-genera level. Remarkably, antimicrobial spectra of Cg-BigDef1 and Cg-BigDef5 were complementary, and peptides acted synergistically. Overall, we found that primary sequence diversification of Cg-BigDefs has generated specificity and synergy and extended the spectrum of activity of this peptide family. 相似文献
134.
The near infrared reflectance spectroscopy (NIRS) method was used in the present study to compare earthworm-made soil aggregates to aggregates found in the surrounding bulk soil. After initially assessing the daily cast production of Metaphire posthuma, boxes with soil incubated with M. posthuma and control soils were subjected to wetting in order to reorganize the soil structure. After two months of incubation, soil aggregates produced by earthworms (casts and burrows), soil aggregates that were appeared to be unaffected by earthworms (bulk soil without visible trace of earthworm bioturbation from the earthworm treatment) and soil aggregates that were entirely unaffected by earthworms (control – no earthworm – treatment) were sampled and their chemical signatures analyzed by NIRS. The production of below-ground and surface casts reached 14.9 g soil g worm?1 d?1 and 1.4 g soil g worm?1 d?1, respectively. Soil aggregates from the control soils had a significantly different NIRS signature from those sampled from boxes with earthworms. However, within the earthworm incubation boxes the NIRS signature was similar between cast and burrow aggregates and soil aggregates from the surrounding bulk soil. We conclude that the high cast production by M. posthuma and the regular reorganization of the soil structure by water flow in and through the soil lead to a relatively homogenous soil structure. Given these results, we question the relevance of considering the bulk soil that has no visible activity of earthworm activity as a control to determine the effect of earthworms on soil functioning. 相似文献
135.
Sylvain Poggi Julien Papaïx Claire Lavigne Frédérique Angevin Florence Le Ber Nicolas Parisey Benoît Ricci Fabrice Vinatier Julie Wohlfahrt 《Landscape Ecology》2018,33(10):1679-1690
Context
Agroecosystems produce food and many other services that are crucial for human well-being. Given the scales at which the processes underlying these services take place, agricultural landscapes appear as appropriate spatial units for their evaluation and management. The design of sustainable agricultural landscapes that value these services has thus become a pressing issue but faces major challenges stemming from the diversity of processes, their interactions and the number of scales at stake. Agricultural landscape modelling can provide a key contribution to this design but must still overcome several difficulties to offer reliable tools for decision makers.Objectives
Our study aimed at shedding light on the main scientific and technical difficulties that make the building of landscape models that may efficiently inform decision-makers a complex task, as well as translating them in terms of challenges that can be further investigated and discussed.Methods
We examine current issues and challenges and indicate future research needs to overcome the scientific and technical obstacles in the development of useful agricultural landscape models.Results
We highlight research perspectives to better couple landscape patterns and process models and account for feedbacks, integrate the decisions of multiple stakeholders, consider the spatial and temporal heterogeneity of data and processes, explore alternative landscape organisations and assess multiobjective performance.Conclusion
Coping with the issues and challenges discussed in this paper should improve our understanding of agroecosystems and give rise to new hypotheses, thereby informing future research.136.
Lysosomal glycosphingolipid recognition by NKT cells 总被引:2,自引:0,他引:2
Zhou D Mattner J Cantu C Schrantz N Yin N Gao Y Sagiv Y Hudspeth K Wu YP Yamashita T Teneberg S Wang D Proia RL Levery SB Savage PB Teyton L Bendelac A 《Science (New York, N.Y.)》2004,306(5702):1786-1789
NKT cells represent a distinct lineage of T cells that coexpress a conserved alphabeta T cell receptor (TCR) and natural killer (NK) receptors. Although the TCR of NKT cells is characteristically autoreactive to CD1d, a lipid-presenting molecule, endogenous ligands for these cells have not been identified. We show that a lysosomal glycosphingolipid of previously unknown function, isoglobotrihexosylceramide (iGb3), is recognized both by mouse and human NKT cells. Impaired generation of lysosomal iGb3 in mice lacking beta-hexosaminidase b results in severe NKT cell deficiency, suggesting that this lipid also mediates development of NKT cells in the mouse. We suggest that expression of iGb3 in peripheral tissues may be involved in controlling NKT cell responses to infections and malignancy and in autoimmunity. 相似文献
137.
Sandeep Raj Karna Paul Chambers Craig B. Johnson Preet Singh Lauren A. Stewart Nicolas Lopez-Villalobos Kavitha Kongara 《Journal of veterinary pharmacology and therapeutics》2020,43(6):538-546
This study was conducted to compare the efficacy of combinations of morphine, dexmedetomidine and maropitant in preventing the changes in electroencephalographic (EEG) indices of nociception in anaesthetized dogs subjected to a noxious electrical stimulus. In a crossover study, eight healthy adult dogs were randomly allocated to four groups: Mor: morphine 0.6 mg/kg; Dex + Mor: morphine 0.3 mg/kg + dexmedetomidine 5 μg/kg; Maro + Mor: morphine 0.3 mg/kg + maropitant 1 mg/kg; and Dex + Maro + Mor: morphine 0.2 mg/kg + dexmedetomidine 3 μg/kg + maropitant 0.7 mg/kg. Following intramuscular administration of test drugs in a minimal anaesthesia model, a supramaximal electrical stimulus (50 V at 50 Hz for 2 s) was applied and the EEG data were recorded. There were significant increases (p < .05) in the poststimulus median frequency (F50) only in groups Mor and Maro + Mor. Dex + Mor group had a significantly lower change in F50 and F95 compared to all other treatment groups. There was no correlation of the changes in EEG frequencies with blood plasma concentration of the drugs during and after noxious stimulation. Combination of dexmedetomidine and morphine was most effective in abolishing the changes in EEG indices in response to a noxious stimulus indicating a supra-additive interaction between these two drugs. 相似文献
138.
139.
Chemical speciation of mercury (Hg) in a wide variety of combustion flue gas matrices has been determined using the mercury speciation adsorption (MESA) method. The MESA sampling system for gas phase Hg species employs a series of heated, solid phase adsorbent traps. Flue gas oxidized Hg species (Hg(II) and MMHg) are adsorbed by a potassium chloride (KCl) impregnated soda lime sorbent. Elemental Hg (Hg0) is collected by an iodated carbon sorbent after passing through the KCl/soda lime sorbent. Total Hg (Hgt) is determined by summation of species. In the laboratory, cold vapor atomic fluorescence spectroscopy (CVAFS) is used for detection of Hg collected on the solid sorbents, after appropriate sample digestion and preparation. The MESA method has been evaluated for species stability, matrix effects, breakthrough, artifacts and precision. Based on eight duplicate samples a mean precision of 6.8% 11% and 4.5% (relative percent difference) has been calculated for Hg0, Hg(II) and Hgt respectively. Intercomparison of the MESA method with other methods shows very good agreement for Hgt. Mass balance calculations at 5 sites range from 75 to 140%, with a mean of 97±25%. Overall mean speciation results from 19 separate determinations suggest that Hg(II) has a 1 sigma range of 40 to 94% in coal combustion flue gas at, the inlet to pollution control devices. 相似文献
140.
Larvicidal and residual activity of imidazolium salts against Aedes aegypti (Diptera: Culicidae) 下载免费PDF全文
Emanuelle Goellner Ademir Tramontini Schmitt Júlia Lacerda Couto Nicolas Drumm Müller Harry Luiz Pilz‐Junior Henri Stephan Schrekker Carlos Eugenio Silva Onilda Santos da Silva 《Pest management science》2018,74(4):1013-1019