全文获取类型
收费全文 | 338篇 |
免费 | 25篇 |
专业分类
林业 | 26篇 |
农学 | 20篇 |
基础科学 | 2篇 |
66篇 | |
综合类 | 21篇 |
农作物 | 23篇 |
水产渔业 | 50篇 |
畜牧兽医 | 134篇 |
园艺 | 2篇 |
植物保护 | 19篇 |
出版年
2023年 | 6篇 |
2022年 | 7篇 |
2021年 | 18篇 |
2020年 | 13篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 16篇 |
2016年 | 12篇 |
2015年 | 14篇 |
2014年 | 23篇 |
2013年 | 19篇 |
2012年 | 28篇 |
2011年 | 33篇 |
2010年 | 9篇 |
2009年 | 22篇 |
2008年 | 21篇 |
2007年 | 22篇 |
2006年 | 21篇 |
2005年 | 15篇 |
2004年 | 8篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1977年 | 2篇 |
排序方式: 共有363条查询结果,搜索用时 15 毫秒
271.
Benito-de-la-Víbora J Lascelles BD García-Fernández P Freire M de Segura IA 《Veterinary anaesthesia and analgesia》2008,35(6):501-510
Objective The hypothesis was that Visual Analog Scale (VAS) scores would be lower, and mechanical wound thresholds (MWT) higher, in cats receiving tolfenamic acid compared to those receiving placebo in the postoperative period following elective ovariohysterectomy. Animals Sixty‐nine client‐owned cats. Methods A prospective, randomized, blinded and placebo‐controlled study was performed in cats which underwent ovariohysterectomy following preoperative tolfenamic acid, meloxicam, or placebo. A second dose of the same analgesic was administered 24 hours postoperatively. Assessments were made 1‐hour before induction and 1, 2, 4, 6, 22, and 25 hours postoperatively. Pain was assessed by a blinded observer using Numerical Rating (NRS) and VAS scales. The MWT were measured using a force‐measuring device. Group comparison was performed by using one‐way anova and chi‐squared test for qualitative and quantitative data, respectively, and a mixed model for repeated measurements (p < 0.05). Results Sixty‐five cats were included in the study. There were no differences between groups at baseline. There was a treatment effect on the NRS scores at 6, 22 and 25 hours. The meloxicam group was less painful than controls at 6 and 22 hours; both treatment groups were less painful than controls at 25 hours. There were no differences between groups in VAS for pain or sedation. The number of animals receiving rescue analgesia did not differ between groups. There was a treatment effect on MWT; thresholds in both treatment groups were significantly higher than that observed in controls at all time points. Conclusions Preoperative tolfenamic acid or meloxicam reduced wound sensitivity following ovariohysterectomy in the cat. Clinical relevance Tolfenamic acid and meloxicam administered preoperatively provided a similar analgesic effect in the postoperative period lasting 24 hours. Mechanical thresholds may be a better way of evaluating postoperative analgesia provided by nonsteroidal anti‐inflammatory drugs in cats. 相似文献
272.
Pain mechanisms and their implication for the management of pain in farm and companion animals 总被引:1,自引:0,他引:1
Viñuela-Fernández I Jones E Welsh EM Fleetwood-Walker SM 《Veterinary journal (London, England : 1997)》2007,174(2):227-239
Over the last two decades there has been a dramatic increase in the literature relating to the mechanisms and management of pain in domestic animals. Understanding the mechanisms of pain is crucial for its effective management. This review highlights the current understanding of the neurophysiology of nociception and the plastic changes involved in chronic pain states. Additionally, we describe a range of novel molecules and pathways that offer opportunities for the development of mechanism-based analgesic therapies. Pain management in animals is limited by pain assessment which remains highly subjective, with clinicians relying on indirect measures of pain, using rating scales and (less frequently) quantifiable physiological and behavioural parameters. The need for a systematic approach which would assess different pain components is well justified. Species-specific issues on pain assessment and management in mammalian companion and farm animals are addressed in the later part of this review. 相似文献
273.
Balcázar JL de Blas I Ruiz-Zarzuela I Vendrell D Gironés O Muzquiz JL 《Comparative immunology, microbiology and infectious diseases》2007,30(2):111-118
The aim of this study was to identify lactic acid bacteria (LAB) using polymerase chain reaction (PCR) amplification of variable regions of the 16S rRNA gene. Thirteen LAB strains were isolated from the intestinal microbiota of healthy salmonids. A approximately 500-bp region of the highly conserved 16S rRNA gene was PCR-amplified and following this, a portion of the amplicon (272-bp) including the V1 and V2 variable regions was sequenced. The sequence containing both the V1 and V2 region provided strong evidence for the identification of LAB. The LAB strains were identified as Carnobacterium maltaromaticum, Lactobacillus curvatus, Lactobacillus sakei, Lactobacillus plantarum, Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis, and Leuconostoc mesenteroides. The method described was found to be a very simple, rapid, specific, and low-cost tool for the identification of unknown strains of LAB. 相似文献
274.
Diéguez FJ Arnaiz I Sanjuán ML Vilar MJ López M Yus E 《Preventive veterinary medicine》2007,82(3-4):321-326
Prior to establishing a control and prevention program for Johne's disease in cattle in Galicia (northwest Spain), a survey was conducted to estimate the prevalence of the disease. For this survey, 61,069 animals of at least 1-year of age from 2735 randomly selected herds were bled and samples analyzed with a commercial ELISA. The estimated true individual-level prevalences – assuming the manufacturer's reported test sensitivity of 48.5% and specificity of 98.9% – were 3.02% in dairy cattle, 1.03% in beef cattle and 2.83% in animals from farms with both dairy and beef cattle. True herd prevalences (with herds declared positive if one or more animals tested positive) were 10.69% for dairy herds, 0% for beef herds and 2.71% for mixed herds. When herds were declared positive if at least two animals tested positive, true herd prevalences were 14.75% for dairy herds, 1.47% for beef herds and 12.01% for mixed herds. Assuming a higher specificity of 99.4%, true individual-level prevalences increased to 4.03% in dairy herds, 2.07% in beef herds and 3.84% in mixed herds. Herd prevalences were 27.77%/18.79%, 2.78%/2.40% and 5.70%/12.24% (using the one/two-animal cut-offs) in dairy, beef and mixed herds, respectively. In conclusion, these results seem to indicate that a small percentage of cows and a rather high percentage of dairy herds in this region are MAP-seropositive. 相似文献
275.
A comprehensive phylogeny of beetles reveals the evolutionary origins of a superradiation 总被引:1,自引:0,他引:1
Hunt T Bergsten J Levkanicova Z Papadopoulou A John OS Wild R Hammond PM Ahrens D Balke M Caterino MS Gómez-Zurita J Ribera I Barraclough TG Bocakova M Bocak L Vogler AP 《Science (New York, N.Y.)》2007,318(5858):1913-1916
Beetles represent almost one-fourth of all described species, and knowledge about their relationships and evolution adds to our understanding of biodiversity. We performed a comprehensive phylogenetic analysis of Coleoptera inferred from three genes and nearly 1900 species, representing more than 80% of the world's recognized beetle families. We defined basal relationships in the Polyphaga supergroup, which contains over 300,000 species, and established five families as the earliest branching lineages. By dating the phylogeny, we found that the success of beetles is explained neither by exceptional net diversification rates nor by a predominant role of herbivory and the Cretaceous rise of angiosperms. Instead, the pre-Cretaceous origin of more than 100 present-day lineages suggests that beetle species richness is due to high survival of lineages and sustained diversification in a variety of niches. 相似文献
276.
Enrico Francia Alessandro Tondelli Fulvia Rizza Franz W. Badeck Orazio Li Destri Nicosia Taner Akar Stefania Grando Adnan Al-Yassin Abdelkader Benbelkacem William T.B. Thomas Fred van Eeuwijk Ignacio Romagosa A. Michele Stanca Nicola Pecchioni 《Field Crops Research》2011
Barley grain yield in rainfed Mediterranean regions can be largely influenced by terminal drought events. In this study the ecophysiological performance of the ‘Nure’ (winter) × ‘Tremois’ (spring) barley mapping population (118 Doubled Haploids, DHs) was evaluated in a multi-environment trial of eighteen site–year combinations across the Mediterranean Basin during two consecutive harvest years (2004 and 2005). Mean grain yield of sites ranged from 0.07 to 5.43 t ha−1, clearly dependent upon both the total water input (rainfall plus irrigation) and the water stress index (WSI) accumulated during the growing season. All DHs were characterized for possessing molecular marker alleles tagging four genes that regulate barley cycle, i.e. Vrn-H1, Vrn-H2, Ppd-H2 and Eam6. Grain yield differences were initially interpreted in terms of mean differences between genotypes (G), environments (E), and for each combination of genotype and environment (GE) through a “full interaction” ANOVA model. Variance components estimates clearly showed the greater importance of GE over G, although both were much lower than E. Alternative linear and bilinear models of increasing complexity were used to describe GE. A linear model fitting allelic variation at the four genes explained genotype main effect and genotype × environment interaction much better than growth habit itself. Adaptation was primarily driven by the allelic constitution at three out of the four segregating major genes, i.e. Vrn-H1, Ppd-H2 and Eam6. In fact, the three genes together explained 47.2% of G and 26.3% of GE sum of squares. Grain yield performance was more determined by the number of grains per unit area than by the grain weight (phenotypic correlation across all genotypic values: r = 0.948 and 0.559, respectively). The inter-relationships among a series of characters defining grain yield and its components were also explored as a function of the length of the different barley developmental phases, i.e. vegetative, reproductive, and grain filling stages. In most environments, the best performing (adapted) genotypes were those with faster development until early occurrence of anthesis. This confirmed the crucial role of the period defining the number of grains per unit area in grain yield determination under Mediterranean environments. 相似文献
277.
de la Luz Cádiz-Gurrea María Fernández de las Nieves Ignacio Aguilera Saez Luis Manuel Fernández-Arroyo Salvador Legeai-Mallet Laurence Bouaziz Mohamed Segura-Carretero Antonio 《Plant foods for human nutrition (Dordrecht, Netherlands)》2019,74(1):40-46
Plant Foods for Human Nutrition - Plants, including most food and feed plants, produce a broad range of bioactive chemical compounds. Among these compounds, polyphenols are reported to provide... 相似文献
278.
QTL mapping for tolerance of anaerobic germination from IR64 and the aus landrace Nanhi using SNP genotyping 总被引:1,自引:0,他引:1
Miriam D. Baltazar John Carlos I. Ignacio Michael J. Thomson Abdelbagi M. Ismail Merlyn S. Mendioro Endang M. Septiningsih 《Euphytica》2014,197(2):251-260
Direct seeding is becoming more popular mainly due to its labor-saving nature. However, flooding during germination caused by unleveled fields and unpredicted heavy rain can prevent crop establishment. On the other hand, flooding just after sowing protects the seeds from rats and birds and is also a viable means of weed control. Thus, the development of varieties able to tolerate flooding during germination, referred to as anaerobic germination (AG), is essential. A study was conducted to identify QTLs associated with tolerance of flooding during germination from an F2:3 mapping population derived from the cross of IR64 and the tolerant aus landrace Nanhi. Phenotyping was performed by counting the rate of seedling survival of 300 lines under the stress. Selective genotyping was employed by genotyping the 48 most tolerant and 48 most susceptible lines using a 384-plex SNP Indica/Indica set on the Illumina BeadXpress Reader, resulting in 234 polymorphic markers for the study. A major QTL for AG derived from Nanhi, named qAG7, was detected on chromosome 7 with an LOD of 13.93 and 22.3 % of the phenotypic variance explained. A second QTL of smaller effect, qAG11, was also derived from Nanhi, while one QTL with an increased effect from IR64 was detected on chromosome 2 (qAG2.1). The QTLs detected in this study can be used to further elucidate the mechanisms underlying AG tolerance in rice, and can also be used in marker-assisted selection and QTL pyramiding to provide higher AG tolerance to enable improved crop establishment in direct-seeded systems. 相似文献
279.
280.
Anabel Elisa Rodríguez Alicia Couto Ignacio Echaide Leonhard Schnittger Monica Florin-Christensen 《Veterinary parasitology》2010,167(2-4):227-235
Autonomous glycosylphosphatidylinositol (GPI) molecules (also protein-free GPIs or free GPIs) have been reported to be particularly abundant in some parasitic protozoa and mediate strong immunomodulatory effects on the host immune system. In the work at hand we have investigated the existence of free GPIs in Babesia bovis. Comparative thin layer chromatographic analysis of the protein-free glycolipid fraction of in vitro cultured B. bovis merozoites and erythrocyte membranes demonstrated the presence of an abundant parasite-specific band. Its chemical analysis revealed a GPI species containing a chain of two mannose residues, N-glucosamine and non-acylated inositol. The lipid moiety linked to inositol was diacylglycerol. The total fatty acid composition showed predominantly long-carbon chain molecules (12% of C22:0 and 45% of C24:0). The potential of B. bovis to assemble the presented free GPI species was verified by the existence of seven genes in its genome that putatively encode the following GPI biosynthetic enzymes: PI N-acetyl-GlcN-transferase (PIG-A and GPI-1), N-acetyl-GlcN-PI-de-N-acetylase (PIG-L), acyltransferase (PIG-W), dolichyl-phosphate mannosyl transferase (DPM-1), GPI mannosyltransferase I (PIG-M), and GPI mannosyltransferase II (PIG-V). GPI biosynthesis is vital for the intraerythrocytic parasite stage as mannosamine, an inhibitor of GPI biosynthesis, impaired in vitro growth of B. bovis merozoites. Absence of the vast majority of N-glycan metabolism encoding genes in the B. bovis genome underscores that the growth inhibitory effect of mannosamine is attributable to its interference with GPI biosynthesis and not with assembly of N-linked oligosaccharides, as has been described for higher eukaryotes. Elucidation of the structure and biosynthesis of GPI may allow to facilitate the development of future immune interventions against bovine babesiosis. 相似文献