全文获取类型
收费全文 | 550篇 |
免费 | 40篇 |
国内免费 | 63篇 |
专业分类
林业 | 12篇 |
农学 | 21篇 |
基础科学 | 3篇 |
40篇 | |
综合类 | 243篇 |
农作物 | 23篇 |
水产渔业 | 29篇 |
畜牧兽医 | 248篇 |
园艺 | 6篇 |
植物保护 | 28篇 |
出版年
2024年 | 2篇 |
2023年 | 17篇 |
2022年 | 39篇 |
2021年 | 49篇 |
2020年 | 40篇 |
2019年 | 27篇 |
2018年 | 21篇 |
2017年 | 28篇 |
2016年 | 18篇 |
2015年 | 21篇 |
2014年 | 34篇 |
2013年 | 24篇 |
2012年 | 43篇 |
2011年 | 37篇 |
2010年 | 24篇 |
2009年 | 27篇 |
2008年 | 25篇 |
2007年 | 29篇 |
2006年 | 25篇 |
2005年 | 21篇 |
2004年 | 24篇 |
2003年 | 11篇 |
2002年 | 9篇 |
2001年 | 12篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1998年 | 2篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有653条查询结果,搜索用时 15 毫秒
131.
Determination of the intramammary dose of benzylpenicillin required to maintain an adequate concentration in the milk to inhibit Gram‐positive bacteria in the clinically normal udder for 24 hr
下载免费PDF全文
![点击此处可从《Journal of veterinary pharmacology and therapeutics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Elke Abbeloos Satu Pyörälä Päivi Rajala‐Schultz Vesa Myllys 《Journal of veterinary pharmacology and therapeutics》2018,41(5):691-698
The aim of this study was to determine the intramammary dose of benzylpenicillin required to maintain a concentration in the milk above the MIC for the Gram‐positive bacteria that cause mastitis. The product used in this study was a commercially available procaine benzylpenicillin in an oily suspension with micronized particles. Three dose levels were used: 200,000, 300,000, and 600,000 IU. Concentrations of benzylpenicillin in cow milk and plasma were determined after a single intramammary dose was administered into one quarter of each of the five cows in each treatment group. Samples were analyzed using an HPLC‐MS/MS method, which was validated during the study. Concentrations in the milk were well above the MIC for the target pathogens for all doses tested. There was a linear dose‐dependent increase in the mean AUCs of benzylpenicillin concentrations in plasma and milk. At the first milking, 12 hr after dosing, there was a significant difference between the mean milk benzylpenicillin concentrations in cows treated with a dose of 600,000 IU, and those treated with 200,000 or 300,000 IU. Although this study shows a linear relationship between the dose of procaine benzylpenicillin administered and the concentration in the milk in the healthy udder, it would be useful to conduct studies on cows with mastitis to define the optimum dose and duration of intramammary treatment with benzylpenicillin. 相似文献
132.
采用超高效液相色谱串联高分辨四极杆飞行时间质谱法(UPLC-Q-TOP-MS)结合大环内酯类抗生素数据库,建立快速筛查鉴别猪血浆中常见大环内酯类抗生素的方法。猪血浆经甲醇提取,通过UPLC-Q-TOP-MS正离子模式全扫描分析,采用Agilent Extend-C18色谱柱(50×2.1 mm,1.8μm)分离,以乙腈-2 mmol/L乙酸铵水溶液(含0.1%甲酸)为流动相梯度洗脱,流速0.4 m L/min,柱温40℃,得到猪血浆中大环内酯类抗生素准分子离子峰精确质量数、主要碎片峰的精确质量数和保留时间后,结合大环内酯类抗生素数据库筛查,实现猪血浆中大环内酯类抗生素的快速定性识别。所建数据库包含26种常见猪血浆中大环内酯类抗生素的准分子离子峰精确质量数、主要碎片峰的精确质量数和保留时间,其中13种常见大环内酯类抗生素的检测限在1.00~8.00ng/g范围内。该方法分离度高、检测灵敏,可以作为快速筛查鉴别猪血浆中大环内酯类抗生素的有效方法。 相似文献
133.
Gut microbes limit growth in house sparrow nestlings (Passer domesticus) but not through limitations in digestive capacity
下载免费PDF全文
![点击此处可从《Integrative zoology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Kevin D. KOHL Antonio BRUN Seth R. BORDENSTEIN Enrique CAVIEDES‐VIDAL William H. KARASOV 《Integrative zoology》2018,13(2):139-151
Recent research often lauds the services and beneficial effects of host‐associated microbes on animals. However, hosting these microbes may come at a cost. For example, germ‐free and antibiotic‐treated birds generally grow faster than their conventional counterparts. In the wild, juvenile body size is correlated with survival, so hosting a microbiota may incur a fitness cost. Avian altricial nestlings represent an interesting study system in which to investigate these interactions, given that they exhibit the fastest growth rates among vertebrates, and growth is limited by their digestive capacity. We investigated whether reduction and restructuring of the microbiota by antibiotic treatment would: (i) increase growth and food conversion efficiency in nestling house sparrows (Passer domesticus); (ii) alter aspects of gut anatomy or function (particularly activities of digestive carbohydrases and their regulation in response to dietary change); and (iii) whether there were correlations between relative abundances of microbial taxa, digestive function and nestling growth. Antibiotic treatment significantly increased growth and food conversion efficiency in nestlings. Antibiotics did not alter aspects of gut anatomy that we considered but depressed intestinal maltase activity. There were no significant correlations between abundances of microbial taxa and aspects of host physiology. Overall, we conclude that microbial‐induced growth limitation in developing birds is not driven by interactions with digestive capacity. Rather, decreased energetic and material costs of immune function or beneficial effects from microbes enriched under antibiotic treatment may underlie these effects. Understanding the costs and tradeoffs of hosting gut microbial communities represents an avenue of future research. 相似文献
134.
135.
Alan W Duttlinger Ruth E Centeno Martinez Betty R McConn Kouassi R Kpodo Donald C Lay Jr Brian T Richert Timothy A Johnson Jay S Johnson 《Journal of animal science》2021,99(6)
Previous research demonstrates that supplementing 0.20% l-glutamine (GLN) in the diets of newly weaned and transported pigs improves growth rate to a similar extent as providing dietary antibiotics (AB). However, research comparing the effects of GLN vs. AB on intestinal physiology and the microbiome is limited. Therefore, the study objective was to compare the effects of supplementing nursery diets with GLN, AB, or no dietary antibiotics (NA) on intestinal physiology and the microbiome of pigs in a production environment following weaning and transport. Mixed-sex piglets (N = 480; 5.62 ± 0.06 kg body weight [BW]) were weaned (18.4 ± 0.2 d of age) and transported for 12 h in central Indiana, for two replicates, during the summer of 2016 and the spring of 2017. Pens were blocked by BW and allotted to one of the three dietary treatments (n = 10 pens/dietary treatment/replicate [8 pigs/pen]): AB (chlortetracycline [441 ppm] + tiamulin [38.6 ppm]), GLN (0.20% as-fed), or NA fed for 14 d. From day 14 to 34, pigs were fed common AB-free diets in two phases. On day 33, villus height:crypt depth tended to be increased (P = 0.07; 7.0%) in GLN and AB pigs vs. NA pigs. On day 33, glucagon-like peptide 2 (GLP-2) mRNA abundance was decreased (P = 0.01; 50.3%) in GLN and NA pigs vs. AB pigs. Crypt depth was increased overall on day 33 (P = 0.01; 16.2%) during the spring replicate compared with the summer replicate. Villus height:crypt depth was reduced (P = 0.01; 9.6%) during the spring replicate compared with the summer replicate on day 33. On day 13, tumor necrosis factor-alpha and occludin mRNA abundance was increased (P ≤ 0.04; 45.9% and 106.5%, respectively) and zonula occludens-1 mRNA abundance tended to be greater (P = 0.10; 19.2%) in the spring replicate compared with the summer replicate. In addition, AB pigs had increased (P = 0.01; 101.3%) GLP-2 mRNA abundance compared with GLN and NA pigs. Microbiome analysis indicated that on day 13, dietary treatment altered the microbiota community structure (P = 0.03). Specifically, the AB pigs tended to be distinct from both the NA and GLN pigs (P = 0.08), and Lactobacillus was increased nearly 2-fold in AB compared with NA pigs (q = 0.04) and GLN pigs (q = 0.22). In conclusion, GLN supplementation tended to improve some morphological markers of intestinal health similarly to AB pigs, while the microbiome composition in GLN pigs was more similar to NA pigs than AB pigs. 相似文献
136.
137.
138.
Merchant ME Leger N Jerkins E Mills K Pallansch MB Paulman RL Ptak RG 《Veterinary immunology and immunopathology》2006,110(3-4):221-228
Leukocytes were isolated from whole blood of wild alligators by differential sedimentation. The leukocytes were disrupted in 5% AcOH and the crude extracts processed by ultrafiltration. The extracts were subjected to solvent exchange (0.1% AcOH) and the fraction that contained macromolecules between 1 and 10 kDa were subjected to further analyses. The acid extracts of the alligator leukocytes exhibited substantial antimycotic activities against six of eight species of Candida yeast tested. In addition, the alligator leukocyte extracts were effective as antimicrobial agents against 10 of 12 bacterial species, and displayed moderate activity against two enveloped viruses (human immunodeficiency virus-1 and herpes simplex virus-1HF). Kinetic analyses revealed that the antimycotic effects of the leukocyte extract occurred rapidly, with 64% fungal growth inhibition within 3 min of exposure. The molecule(s) responsible for the antimicrobial activities were sensitive to proteases, heat-stable, acid soluble, and in the 1–10 kDa range. These data suggest that alligator leukocytes express cationic peptides that are responsible for their antimicrobial properties. 相似文献
139.
通过对甘肃省平凉市畜牧业发展的现状、存在问题、中草药饲料添加剂发展历史和优势、发展中草药饲料添加剂的前景4个方面的阐述,旨在让平凉市的动物养殖人员更加了解中草药这种纯天然的饲料添加剂,并将其应用于生产实践中,为平凉市的畜牧业健康发展提供绿色饲料产品。 相似文献
140.
Prasannan Geetha Preena Arathi Dharmaratnam Vattiringal Jayadradhan Rejish Kumar Thangaraj Raja Swaminathan 《Aquaculture Research》2021,52(1):237-248
For the sustainable farming of tilapia, proper maintenance of their health and adequate treatment for infections at appropriate time are inevitable. The indiscriminate use of antibiotics in aquaculture, as a part of treatment and as growth promoters, accelerates antimicrobial resistance (AMR) among the fish pathogens. In the present study, we have isolated diverse aeromonads from Nile tilapia and studied their antibiogram and plasmid profiling. Aeromonas hydrophila, Aeromonas veronii, Aeromonas sobria, Aeromonas dhakensis, Aeromonas caviae, Aeromonas jandaei and Aeromonas aquatica were isolated from infected tilapia (n = 150), and their Shannon wiener diversity index was calculated as 1.926. A. veronii was found to be the most multiple antibiotic‐resistant pathogen with the MAR index of 0.46, and A. aquatica was noticed as the least resistant isolate. The minimum inhibitory concentration of resistant antibiotics was shown as >256 mcg/ml for most of the isolates. The virulent genes such as aerolysin and hemolysin were identified in all the isolates except A. aquatica. The detection of class 1 integrons, plasmid profiling and plasmid curing studies confirmed that AMR exhibited by most of the Aeromonas species is of plasmid mediated. This challenges the risk of wide spread of AMR among the pathogens and subsequent treatment of the infection. 相似文献