全文获取类型
收费全文 | 2101篇 |
免费 | 160篇 |
国内免费 | 243篇 |
专业分类
林业 | 161篇 |
农学 | 55篇 |
基础科学 | 52篇 |
325篇 | |
综合类 | 816篇 |
农作物 | 21篇 |
水产渔业 | 45篇 |
畜牧兽医 | 912篇 |
园艺 | 73篇 |
植物保护 | 44篇 |
出版年
2024年 | 9篇 |
2023年 | 100篇 |
2022年 | 120篇 |
2021年 | 112篇 |
2020年 | 116篇 |
2019年 | 116篇 |
2018年 | 75篇 |
2017年 | 79篇 |
2016年 | 100篇 |
2015年 | 68篇 |
2014年 | 139篇 |
2013年 | 188篇 |
2012年 | 226篇 |
2011年 | 197篇 |
2010年 | 151篇 |
2009年 | 158篇 |
2008年 | 91篇 |
2007年 | 84篇 |
2006年 | 89篇 |
2005年 | 80篇 |
2004年 | 61篇 |
2003年 | 41篇 |
2002年 | 16篇 |
2001年 | 17篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 16篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 1篇 |
排序方式: 共有2504条查询结果,搜索用时 15 毫秒
71.
72.
兽药行业的现状与发展展望 总被引:5,自引:3,他引:2
从生产能力、企业数量、新药研发评审等总结了国内外兽药行业的现状,并对国内兽药生产企业的研发工作提出了展望。 相似文献
73.
Marion Florin Elina Rusanen† Michael Haessig‡ Marianne Richter Bernhard M. Spiess 《Veterinary ophthalmology》2009,12(6):350-356
Objective To document the clinical presentation, diagnostics, treatment, and clinical outcome of rabbits with dacryocystitis.
Materials and methods This retrospective study included 28 rabbits diagnosed with dacryocystitis. Available records of clinical and ophthalmological examinations, bacteriological samplings, diagnostic imaging, and treatment were reviewed. A telephone survey of the owners was conducted to evaluate recovery and recurrences.
Results The mean age of the 28 rabbits presenting with ocular discharge from the nasolacrimal duct was 4.4 years. In 25 rabbits (89%), dacryocystitis was a unilateral finding. No underlying cause could be determined in 10 animals (35%). Dental malocclusion was observed in 14 rabbits (50%) and rhinitis in two animals (7%), with one animal showing both symptoms (4%). One rabbit (4%) presented with panophthalmitis. Most animals (96%) received topical antibiotic treatment. If necessary, additional topical (acetylcysteine, vitamin A ointment, nonsteroidals) or systemic treatment (antibiotics, nonsteroidals, paramunity inducer, and glucocorticoids) was provided. The mean duration of therapy was 5.8 weeks. The nasolacrimal duct was flushed in 27 of 31 affected eyes (87%). Dentistry was performed in 80% of the animals suffering from malocclusion. Regarding the clinical outcome, 12 animals (43%) showed complete recovery, eight rabbits (28%) were euthanized, three (11%) died due to unrelated causes, and three (11%) were lost to follow-up. Two rabbits (7%) continue to display signs of dacryocystitis and are being treated symptomatically by the owners.
Conclusions This study reports the clinical presentation, treatment, and outcome of dacryocystitis in rabbits and outlines the importance of examination of the oral cavity, diagnostic imaging, and bacteriologic sampling. 相似文献
Materials and methods This retrospective study included 28 rabbits diagnosed with dacryocystitis. Available records of clinical and ophthalmological examinations, bacteriological samplings, diagnostic imaging, and treatment were reviewed. A telephone survey of the owners was conducted to evaluate recovery and recurrences.
Results The mean age of the 28 rabbits presenting with ocular discharge from the nasolacrimal duct was 4.4 years. In 25 rabbits (89%), dacryocystitis was a unilateral finding. No underlying cause could be determined in 10 animals (35%). Dental malocclusion was observed in 14 rabbits (50%) and rhinitis in two animals (7%), with one animal showing both symptoms (4%). One rabbit (4%) presented with panophthalmitis. Most animals (96%) received topical antibiotic treatment. If necessary, additional topical (acetylcysteine, vitamin A ointment, nonsteroidals) or systemic treatment (antibiotics, nonsteroidals, paramunity inducer, and glucocorticoids) was provided. The mean duration of therapy was 5.8 weeks. The nasolacrimal duct was flushed in 27 of 31 affected eyes (87%). Dentistry was performed in 80% of the animals suffering from malocclusion. Regarding the clinical outcome, 12 animals (43%) showed complete recovery, eight rabbits (28%) were euthanized, three (11%) died due to unrelated causes, and three (11%) were lost to follow-up. Two rabbits (7%) continue to display signs of dacryocystitis and are being treated symptomatically by the owners.
Conclusions This study reports the clinical presentation, treatment, and outcome of dacryocystitis in rabbits and outlines the importance of examination of the oral cavity, diagnostic imaging, and bacteriologic sampling. 相似文献
74.
兽医药理学实验是一门实践性很强的实验课程,其教学效果直接影响该专业整体教学质量的高低。在药理学实验教学中,从丰富教学内容,提高教学质量;改善教学方法,提高授课水平;增加实践机会,提高实践技能三个方面对兽医药理学实验教学进行改革,为培养实用型兽医专业人才提供保证。 相似文献
75.
76.
77.
Sibylle K. Hassler Beate Zimmermann Michiel van BreugelJefferson S. Hall Helmut Elsenbeer 《Forest Ecology and Management》2011,261(10):1634-1642
Landscapes in the humid tropics are undergoing a continuous change in land use. Deforestation is still taking its toll on forested areas, but at the same time more and more secondary forests emerge where formerly agricultural lands and pastures are being abandoned. Regarding soil hydrology, the extent to which secondary succession can recover soil hydrological properties disturbed by antecedent deforestation and pasture use is yet poorly understood. We investigated the effect of secondary succession on saturated hydraulic conductivity (Ks) at two soil depths (0-6 and 6-12 cm) using a space-for-time approach in a landscape mosaic in central Panama. The following four land-use classes were studied: pasture (P), secondary forest of 5-8 years of age (SF5), secondary forest of 12-15 years of age (SF12) and secondary forest of more than 100 years of age (SF100), each replicated altogether four times in different micro-catchments across the study region. The hydrological implications of differences in Ks in response to land-use change with land use, especially regarding overland flow generation, were assessed via comparisons with rainfall intensities.Recovery of Ks could be detected in the 0-6 cm depth after 12 years of secondary succession: P and SF5 held similar Ks values, but differed significantly (α = 0.05) from SF12 and SF100 which in turn were indistinguishable. Variability within the land cover classes was large but, due to sufficient replication in the study, Ks recovery could be detected nonetheless. Ks in the 6-12 cm depth did not show any differences between the land cover classes; only Ks of the uppermost soil layer was affected by land-use changes. Overland flow - as inferred from comparisons of Ks with rainfall intensities - is more likely on P and SF5 sites compared to SF12 and SF100 for the upper sample depth; however, generally low values at the 6-12 cm depth are likely to impede vertical percolation during high rainfall intensities regardless of land use.We conclude that Ks can recover from pasture use under secondary succession up to pre-pasture levels, but the process may take more than 8 years. In order to gain comprehensive understanding of Ks change with land use and its hydrological implications, more studies with detailed land-use histories and combined measurements of Ks, overland flow, precipitation and throughfall are essential. 相似文献
78.
饲料业产值提升和总体规模的发展壮大,对我国乡村振兴和农民脱贫攻坚意义重大。当前我国饲料企业的电商模式主要包括B2B、B2C和O2O等。但大多数饲料企业本身规模较小,技术相对落后,对电商营销的投入也十分有限,严重制约了电商模式的创新发展。为此,本文在大数据和云计算框架下提出一种基于云服务的饲料产品电商模式,以网络层、传输层、服务层和应用层等为基础架构,将云端信息服务与饲料产业链深度融合,在为饲料企业提供海量客户信息的同时,也提升和改善了饲料企业原有的销售模式、售后服务水平和物流效率。
[关键词] 乡村振兴|电商|云服务|产业链 相似文献
79.
Test data generated by ~60 accredited member laboratories of the American Association of Veterinary Laboratory Diagnosticians (AAVLD) is of exceptional quality. These data are captured by 1 of 13 laboratory information management systems (LIMSs) developed specifically for veterinary diagnostic laboratories (VDLs). Beginning ~2000, the National Animal Health Laboratory Network (NAHLN) developed an electronic messaging system for LIMS to automatically send standardized data streams for 14 select agents to a national repository. This messaging enables the U.S. Department of Agriculture to track and respond to high-consequence animal disease outbreaks such as highly pathogenic avian influenza. Because of the lack of standardized data collection in the LIMSs used at VDLs, there is, to date, no means of summarizing VDL large data streams for multi-state and national animal health studies or for providing near-real-time tracking for hundreds of other important animal diseases in the United States that are detected routinely by VDLs. Further, VDLs are the only state and federal resources that can provide early detection and identification of endemic and emerging zoonotic diseases. Zoonotic diseases are estimated to be responsible for 2.5 billion cases of human illness and 2.7 million deaths worldwide every year. The economic and health impact of the SARS-CoV-2 pandemic is self-evident. We review here the history and progress of data management in VDLs and discuss ways of seizing unexplored opportunities to advance data leveraging to better serve animal health, public health, and One Health. 相似文献
80.
王小江 《畜牧兽医科学(电子版)》2021,(4):136-137
在畜禽饲养管理过程中使用违禁药物或滥用药物,使用饲料添加剂或超量用药,不遵守休药期规定等均可引起畜产品兽药残留。同时饲养环境遭到污染也能致使药物残留,并且我国关于食品安全的法律法规不健全、监管力度不够等,致使畜产品中药物残留问题更加严重。人体摄入存在药物残留的食品后,不仅会引起急性、慢性或蓄积性中毒,还会致使机体细菌产生耐药性,甚至污染整个生活环境等。 相似文献