全文获取类型
收费全文 | 157篇 |
免费 | 6篇 |
专业分类
林业 | 15篇 |
农学 | 1篇 |
基础科学 | 2篇 |
31篇 | |
综合类 | 11篇 |
农作物 | 12篇 |
水产渔业 | 6篇 |
畜牧兽医 | 77篇 |
园艺 | 3篇 |
植物保护 | 5篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 11篇 |
2012年 | 12篇 |
2011年 | 22篇 |
2010年 | 13篇 |
2009年 | 7篇 |
2008年 | 5篇 |
2007年 | 8篇 |
2006年 | 9篇 |
2005年 | 11篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2002年 | 7篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有163条查询结果,搜索用时 15 毫秒
71.
Nanoparticles (NPs) are gaining increasing attention for potential application in medicine; consequently, studying their interaction with cells is of central importance. We found that both ligand arrangement and composition on gold nanoparticles play a crucial role in their cellular internalization. In our previous investigation, we showed that 66-34OT nanoparticles coated with stripe-like domains of hydrophobic (octanethiol, OT, 34%) and hydrophilic (11-mercaptoundecane sulfonate, MUS, 66%) ligands permeated through the cellular lipid bilayer via passive diffusion, in addition to endo-/pino-cytosis. Here, we show an analysis of NP internalization by DC2.4, 3T3, and HeLa cells at two temperatures and multiple time points. We study four NPs that differ in their surface structures and ligand compositions and report on their cellular internalization by intracellular fluorescence quantification. Using confocal laser scanning microscopy we have found that all three cell types internalize the 66-34OT NPs more than particles coated only with MUS, or particles coated with a very similar coating but lacking any detectable ligand shell structure, or 'striped' particles but with a different composition (34-66OT) at multiple data points. 相似文献
72.
73.
74.
Tania E. Perez Katrina L. Mealey Neal S. Burke Tamara L. Grubb Michael H. Court Stephen A. Greene 《Veterinary anaesthesia and analgesia》2017,44(2):370-374
Objective
Variants in the MC1R gene have been associated with red hair color and sensitivity to pain in humans. The study objective was to determine if a relationship exists between MC1R genotype and physiological thermal or mechanical nociceptive thresholds in Labrador Retriever dogs.Study design
Prospective experimental study.Animals
Thirty-four Labrador Retriever dogs were included in the study following public requests for volunteers. Owner consent was obtained and owners verified that their dog was apparently not experiencing pain and had not been treated for pain during the previous 14 days. The study was approved by the Institutional Animal Care and Use Committee.Methods
Nociceptive thresholds were determined from a mean of three thermal and five mechanical replications using commercially available algometers. Each dog was genotyped for the previously described MC1R variant (R306ter). Data were analyzed using one-way anova with post hoc comparisons using Tukey’s test (p < 0.05).Results
Thirteen dogs were homozygous wild-type (WT/WT), nine were heterozygous (WT/R306ter), and eight were homozygous variant (R306ter/R306ter) genotype. Four dogs could not be genotyped. A significant difference (p = 0.04) in mechanical nociceptive thresholds was identified between dogs with the WT/WT genotype (12.1 ± 2.1 N) and those with the WT/R306ter genotype (9.2 ± 2.4 N).Conclusion
A difference in mechanical, but not thermal, nociceptive threshold was observed between wild-type and heterozygous MC1R variants. Differences in nociceptive thresholds between homozygous R306ter variants and other genotypes for MC1R were not observed.Clinical relevance
Compared with the wild-type MC1R genotype, nociceptive sensitivity to mechanical force in dogs with a single variant R306ter allele may be greater. However, in contrast to the reported association between homozygous MC1R variants (associated with red hair color) and nociception in humans, we found no evidence of a similar relationship in dogs with the homozygous variant genotype. 相似文献75.
76.
Effect of hydrochloric acid,pepsin, or taurocholate on bioelectric properties of gastric squamous mucosa in horses 总被引:1,自引:0,他引:1
OBJECTIVE: To determine the effect of pH with or without pepsin or taurocholic acid on the bioelectric properties of gastric squamous mucosa in horses. SAMPLE POPULATION: Gastric tissues obtained from 16 adult horses that did not have evidence of gastric disease. PROCEDURE: Bioelectric properties of squamous mucosa were determined, using modified Ussing chambers. Tissues then were exposed to mucosal pepsin (1 mg/ml) or taurocholic acid (2.5 mM) under neutral (pH 74) or acidic (pH 1.7) conditions. RESULTS: Exposure of mucosal sheets to an acidic pH resulted in an immediate and sustained decrease in transmembrane potential difference and calculated tissue resistance. Pepsin or taurocholic acid did not significantly affect bioelectric variables when added to a mucosal bath solution of pH 7.4. A synergistic effect between pepsin or taurocholic acid and mucosal acidification was not detected. CONCLUSIONS AND CLINICAL RELEVANCE: Mucosal acidification with or without pepsin or taurocholic acid resulted in reduced tissue resistance. These data support the contention that squamous erosions or ulcers in horses are mediated, in part, by prolonged exposure of gastric squamous mucosa to luminal acid. 相似文献
77.
An approximately 5‐month‐old American Staffordshire terrier was presented with a history of recurrent peritoneal effusion. Abdominal radiographs and ultrasound showed a loculated effusion in the ventral abdomen with dorsal displacement of abdominal organs, hepatomegaly and rounding of liver and splenic margins. Computed tomography demonstrated centrally located gastrointestinal segments surrounded by a thin soft tissue band and a thickened peritoneal lining. At necropsy a fibrous membrane continuous with liver and splenic capsules encapsulated all abdominal organs. Microscopically the abdominal wall and fibrous capsule consisted of an irregular thick layer of hypocellular connective tissue. The final diagnosis was sclerosing encapsulating peritonitis. 相似文献
78.
Chronic toxicity of unresolved complex mixtures (UCM) of hydrocarbons in marine sediments 总被引:1,自引:4,他引:1
Alan Scarlett Tamara S. Galloway Steven J. Rowland 《Journal of Soils and Sediments》2007,7(4):200-206
Background, Aim and Scope Unresolved complex mixtures (UCM) of hydrocarbons, containing many thousands of compounds which cannot be resolved by conventional
gas chromatography (GC), are common contaminants of sediments but little is known of their potential to affect sediment-dwelling
organisms. Evidence exists for reduced health status in mussels, arising from aqueous exposure to aromatic UCM components
acting through a narcotic mode of action. However, UCM contaminants in sediments may not be sufficiently bioavailable to elicit
toxic effects. The aim of our study was therefore to measure the sublethal effects of chronic exposure to model UCM-dominated
oils at environmentally realistic concentrations and compare this to effects produced by a UCM containing weathered crude
oil. A further aim was to determine which, if any, fractions of the oils were responsible for any observed toxicity.
Materials and Methods Whole oils were spiked into estuarine sediment to give nominal concentrations of 500 μg g−1 dry weight. Juveniles of the estuarine amphipod Corophium volutator were exposed to the contaminated sediment for 35 days and their survival, growth rate and reproductive success quantified.
Using an effect-directed fractionation approach, the oils were fractionated into aliphatic and two aromatic fractions by open
column chromatography and their toxicity assessed by further chronic exposures using juvenile C. volutator.
Results The growth rates of amphipods were reduced following exposure to the oils although this was only statistically significant
for the weathered oil; reproductive success was reduced by all oil exposures. Sediment spiked with UCM fractions also caused
reduced growth and reproduction but no particular fraction was found to be responsible for the observed toxicity. Survivorship
was not affected by any oil or fraction.
Discussion The study showed that chronic exposure to sediments contaminated by UCM-dominated oils could have population level effects
on amphipods. The observed effects could not be explained by hydrocarbons resolved by conventional GC and effects were similar
for both UCM-dominated and weathered oils. All of the fractions appeared to contribute to the observed effects; this is in
contrast to previous research which had shown that an aliphatic UCM did not cause adverse effects in mussels.
Conclusions To our knowledge, this is the first study to demonstrate population-level effects arising from exposure to sediments contaminated
by realistic environmental concentrations of UCM hydrocarbons. The results are consistent with many compounds, at very low
individual concentrations, contributing towards the overall observed toxicity.
Recommendations Risk assessments of contaminated sediments should take into account the contribution towards the potential for toxic effects
from UCM hydrocarbons. Studies into sediment contamination should report both aliphatic and aromatic UCM concentrations to
aid risk assessments.
ESS-Submission Editor: Henner Hollert (hollert@uni-heidelberg.de)
This paper has been developed from a presentation at SETAC Europe 16th Annual Meeting 2006 held at the The Hague, The Netherlands. 相似文献
79.
80.
Tamara Grubb Anna Edner Jan HM Frendin Pia Funkquist Anneli Rydén Görel Nyman 《Veterinary anaesthesia and analgesia》2013,40(6):e9-e18
ObjectiveTo assess oxygenation, ventilation‐perfusion (V/Q) matching and plasma endothelin (ET‐1) concentrations in healthy horses recovering from isoflurane anaesthesia administered with or without pulse‐delivered inhaled nitric oxide (iNO).Study DesignProspective experimental trial.AnimalsHealthy adult Standardbred horses.MethodsHorses were anaesthetized with isoflurane in oxygen and placed in lateral recumbency. Six control (C group) horses were anaesthetized without iNO delivery and six horses received pulse‐delivered iNO (NO group). After 2.5 hours of anaesthesia isoflurane and iNO were abruptly discontinued, inhaled oxygen was reduced from 100% to approximately 30%, and the horses were moved to the recovery stall. At intervals during a 30‐minute period following the discontinuation of anaesthesia, arterial and mixed venous blood gas values, shunt fraction (Qs/Qt), plasma ET‐1 concentration, pulse rate and respiratory rate were measured or calculated. Repeated measures anova and a Bonferroni post hoc test was used to analyze data with significance set at p <0.05.ResultsAt all time points in the recovery period, NO horses maintained better arterial oxygenation (oxygen partial pressure: NO 13.2 ± 2.7–11.1 ± 2.7 versus C 6.7 ± 1.1–7.1 ± 1.1 kPa) and better V/Q matching (Qs/Qt NO 0.23 ± 0.05–0.14 ± 0.06 versus C 0.48 ± 0.03–0.32 ± 0.08%) than C horses. Mixed venous oxygenation was higher in NO for 25 minutes following the discontinuation of anaesthesia (NO 6.3 ± 0.2–4.5 ± 0.07 versus C 4.7 ± 0.6–3.7 ± 0.3 kPa). In both groups of horses arterial oxygenation remained fairly stable; venous oxygenation declined over this time period in the NO group but still remained higher than venous oxygen in the C group. ET‐1 concentrations were higher at most time points in C than NO. Changes in other parameters were either minor or absent.Conclusions and Clinical RelevanceDelivery of iNO to healthy horses during anaesthesia results in better arterial and venous oxygenation and V/Q matching (as determined by lower Qs/Qt) and lower ET‐1 concentrations throughout a 30‐minute anaesthetic recovery period. 相似文献