全文获取类型
收费全文 | 27316篇 |
免费 | 1525篇 |
国内免费 | 1579篇 |
专业分类
林业 | 2691篇 |
农学 | 2544篇 |
基础科学 | 1244篇 |
5400篇 | |
综合类 | 5457篇 |
农作物 | 1547篇 |
水产渔业 | 1854篇 |
畜牧兽医 | 6850篇 |
园艺 | 803篇 |
植物保护 | 2030篇 |
出版年
2024年 | 99篇 |
2023年 | 314篇 |
2022年 | 705篇 |
2021年 | 972篇 |
2020年 | 956篇 |
2019年 | 878篇 |
2018年 | 984篇 |
2017年 | 1142篇 |
2016年 | 1026篇 |
2015年 | 1074篇 |
2014年 | 1137篇 |
2013年 | 1429篇 |
2012年 | 1778篇 |
2011年 | 1881篇 |
2010年 | 1369篇 |
2009年 | 1318篇 |
2008年 | 1498篇 |
2007年 | 1442篇 |
2006年 | 1233篇 |
2005年 | 1193篇 |
2004年 | 808篇 |
2003年 | 682篇 |
2002年 | 628篇 |
2001年 | 523篇 |
2000年 | 604篇 |
1999年 | 677篇 |
1998年 | 446篇 |
1997年 | 396篇 |
1996年 | 365篇 |
1995年 | 304篇 |
1994年 | 328篇 |
1993年 | 275篇 |
1992年 | 275篇 |
1991年 | 236篇 |
1990年 | 216篇 |
1989年 | 201篇 |
1988年 | 132篇 |
1987年 | 119篇 |
1986年 | 88篇 |
1985年 | 78篇 |
1984年 | 61篇 |
1983年 | 59篇 |
1982年 | 40篇 |
1980年 | 30篇 |
1979年 | 43篇 |
1978年 | 35篇 |
1977年 | 36篇 |
1974年 | 30篇 |
1973年 | 48篇 |
1972年 | 36篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Alexander de Oliveira El-Warrak Mouhamed Rouma Audrey Amoroso Soren R. Boysen Younés Chorfi 《The Canadian veterinary journal. La revue veterinaire canadienne》2012,53(12):1285-1288
This study compared vitamin A, vitamin E, selenium (Se), and L-lactate in blood and synovial fluid in 2 groups of 6 dogs; a control group (without OA) and an osteoarthritic group with spontaneous cranial cruciate ligament rupture and OA. Concentrations of vitamin E were significantly higher in serum than in synovial fluid in both OA (P = 0.006) and control (P = 0.0008) groups. Vitamin E concentration in synovial fluid was significantly higher in the OA group than in the control group (P = 0.009). Concentrations of Se were significantly higher in serum than in synovial fluid in both OA (P = 0.003) and control (P = 0.0006) groups. There were no significant differences in levels of Se, vitamin A, and L-lactate between the 2 groups. This is the first study to show an increased concentration of vitamin E in the synovial fluid of dogs with OA compared with dogs that did not have OA. 相似文献
52.
ABSTRACT: Foot-and-mouth disease virus (FMVD), one of the most contagious viruses of cloven-hoofed animals, may cause a prolonged, asymptomatic but persistent infection in ruminants, named the "carrier state". However, it remains an open question whether this carrier state occurs in pigs. Here we present quantitative analyses of the duration of FMDV RNA and infectivity in lymphoid and epithelial tissues in experimentally infected pigs with FMDV C-S8c1. The data indicated that although FMDV RNA remained in blood until day 14 post-infection (pi), viremia was cleared by day 7 pi. However, all tissues tested were positive for FMDV until day 14-17 pi. Interestingly, the specific infectivity of FMDV in these tissues was in some cases even higher than the FMDV C-S8c1. We therefore propose that a "pseudopersistent state" may occur in pigs in which virus replicates in lymphoid tissues for a prolonged period of time, thereby representing a potential source of virus. 相似文献
53.
54.
By the radiographic examination of pet and wild birds, veterinary clinicians may relatively easily obtain additional information that can be used routinely in their everyday diagnostic and therapeutic work. The first part of the present review summarizes the basic technical conditions of radiological examinations, analyses the radiographic features of healthy birds, and describes the procedure and radiological indications of contrast radiography. 相似文献
55.
Michal Vla?ín Robert Luká? Zuzana Kauerová Pavel Kohout Josef Ma?ek Eli?ka Bartheldyová ?těpán Koudelka Zina Korvasová Jana Plocková Nikola Hronová Jaroslav Turánek 《Canadian journal of veterinary research》2014,78(2):133-139
Specific contrast ultrasound is widely applied in diagnostic procedures on humans but remains underused in veterinary medicine. The objective of this study was to evaluate the use of microbubble-based contrast for rapid ultrasonographic diagnosis of thrombosis in small animals, using male New Zealand white rabbits (average weight about 3.5 kg) as a model. It was hypothesized that the use of microbubble-based contrast agents will result in a faster and more precise diagnosis in our model of thrombosis. A pro-coagulant environment had been previously established by combining endothelial denudation and external vessel wall damage. Visualization of thrombi was achieved by application of contrast microbubbles [sterically stabilized, phospholipid-based microbubbles filled with sulfur hexafluoride (SF6) gas] and ultrasonography. As a result, rapid and clear diagnosis of thrombi in aorta abdominalis was achieved within 10 to 30 s (mean: 17.3 s) by applying microbubbles as an ultrasound contrast medium. In the control group, diagnosis was not possible or took 90 to 180 s. Therefore, sterically stabilized microbubbles were found to be a suitable contrast agent for the rapid diagnosis of thrombi in an experimental model in rabbits. This contrast agent could be of practical importance in small animal practice for rapid diagnosis of thrombosis. 相似文献
56.
本文在阐述国外重大动物疫病防治数字化监控与预警体系规划研究的概况,国内应用研究现状及对策的同时,指出动物疫病预警研究是公共卫生应急及城市预警应急系统的重要组成部分。风险预警是风险分析的重要内容,风险分析是WTO等协定的构成部分,是技术性贸易措施的重要内容之一,是WTO各成员方检验检疫决策的主要技术支持。风险分析可保持检验检疫的正当技术壁垒作用,充分发挥检验检疫的保护功能,能强化检验检疫贸易的促进作用。针对重大动物疫病严重影响中国畜禽生产产业发展,由于疫病控制不及时,造成重大经济损失。同时,也影响中国畜禽(生猪、牛、禽)活体和胴体出口。为此,研究重大动物疫病风险评估及预警体系的框架构建,形成风险评估及预警决策模型;以及采用基于GIS的数字化监控系统,将流行病学数据库、地理图形、非空间应用模型和空间应用模型有机地结合,实现图形和数据资源共享。系统可及时跟踪疾病的蔓延,通过动物疫病流行病学图分析,可提出适宜的防治措施,达到重大动物疫病的预警预报目的。借鉴国外成功经验,提出适合国情的风险预警的研究内容,指出GIS系统与风险分析在预警体系中应用的注意点,为开展风险评估工作提供更多的素材,奠定风险管理基础。 相似文献
57.
Hjulsager CK Grau-Roma L Sibila M Enøe C Larsen L Segalés J 《Veterinary microbiology》2009,133(1-2):172-178
Several real-time PCR assays for quantification of PCV2 DNA (qPCR) have been described in the literature, and different in-house assays are being used by laboratories around the world. A general threshold of 10(7) copies of PCV2 per millilitre serum for postweaning multisystemic wasting syndrome (PMWS) diagnosis has been suggested. However, neither inter-laboratory nor inter-assay comparisons have been published so far. In the present study, two different qPCR probe assays used routinely in two laboratories were compared on DNA extracted from serum, nasal and rectal swabs. Results showed a significant linear association between the assays (p<0.0001), and a systematic difference of 1.4 log10 copies of PCV2 per millilitre of sample (p<0.0001). This difference indicated that the assay from laboratory 1 yielded a higher output than the one from laboratory 2. Results also showed that there was no linear association between the amount of PCV2 DNA and the amount of total DNA, neither in nasal (p=0.86) nor in rectal (p=0.78) swabs, suggesting that normalizing of PCV2 DNA load in swab samples to total DNA concentration is not suitable. The present exploratory study highlights the need for the performance of ring trials on qPCV2 protocols between laboratories. Meanwhile, the proposed thresholds for PMWS diagnosis should only be considered reliable for each particular laboratory and each particular assay. 相似文献
58.
González Canga A Sahagún Prieto AM José Diez Liébana M Martínez NF Vega MS Vieitez JJ 《Veterinary journal (London, England : 1997)》2009,179(1):25-37
The pharmacokinetic properties of drugs are closely related to their pharmacological efficacy. The kinetics of ivermectin are characterised, in general terms, by a slow absorption process, a broad distribution in the organism, low metabolism, and slow excretion. The kinetics vary according to the route of administration, formulation, animal species, body condition, age, and physiological status, all of which contribute to differences in drug efficacy. Characterisation of ivermectin kinetics can be used to predict and optimise the value of the parasiticide effects and to design programmes for parasite control. This article reviews the pharmacokinetics of ivermectin in several domestic animal species. 相似文献
59.
60.
Martínez J Segura P García D Aduriz G Ibabe JC Peris B Corpa JM 《Veterinary journal (London, England : 1997)》2006,172(2):382-385
A seven-year-old female Indian python (Python molurus) weighing about 35kg was euthanased after several clinical episodes of stomatitis, pneumonia, ophthalmitis and dystocia over a period of four years. The animal had been maintained in a terrarium in a circus truck at an adequate temperature. During shows, however, the snake was considered to be exposed to stressful conditions for several hours at a time at low temperatures and with noise and bright lights. A post-mortem examination indicated ulcerative stomatitis, osteomyelitis, severe pneumonia and numerous granulomata and multifocal necrosis in stomach and spleen. Corynebacterium macginleyi was isolated in pure culture from the ulcerative stomatitis, and mixed with Stenotrophomonas maltophilia from the lungs and spleen. The findings indicated that the snake had died from a septicaemic process caused by C. macginleyi, probably originating from the stomatitis. The role of S. maltophilia as a secondary agent is discussed. The stress of the circus show and poor husbandry may have predisposed the animal to infection and septicaemia. This is the first report of C. macginleyi causing disease in a snake. 相似文献