全文获取类型
收费全文 | 867篇 |
免费 | 88篇 |
专业分类
林业 | 70篇 |
农学 | 13篇 |
基础科学 | 1篇 |
104篇 | |
综合类 | 125篇 |
农作物 | 24篇 |
水产渔业 | 43篇 |
畜牧兽医 | 523篇 |
园艺 | 16篇 |
植物保护 | 36篇 |
出版年
2023年 | 14篇 |
2022年 | 8篇 |
2021年 | 23篇 |
2020年 | 52篇 |
2019年 | 39篇 |
2018年 | 33篇 |
2017年 | 29篇 |
2016年 | 27篇 |
2015年 | 22篇 |
2014年 | 32篇 |
2013年 | 28篇 |
2012年 | 52篇 |
2011年 | 63篇 |
2010年 | 30篇 |
2009年 | 27篇 |
2008年 | 56篇 |
2007年 | 53篇 |
2006年 | 53篇 |
2005年 | 44篇 |
2004年 | 36篇 |
2003年 | 39篇 |
2002年 | 45篇 |
2001年 | 14篇 |
2000年 | 7篇 |
1999年 | 17篇 |
1998年 | 5篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1979年 | 4篇 |
1972年 | 2篇 |
1967年 | 3篇 |
1929年 | 2篇 |
1917年 | 3篇 |
1914年 | 2篇 |
1906年 | 2篇 |
1905年 | 2篇 |
1904年 | 2篇 |
1903年 | 3篇 |
1901年 | 4篇 |
1900年 | 2篇 |
1899年 | 2篇 |
排序方式: 共有955条查询结果,搜索用时 991 毫秒
1.
Polarised light biomicroscopy was used to examine the normal pre-corneal tear film in 21 eyes of 12 pekingese dogs. The purpose of the study was to examine the influence of excessive exophthalmos on the pre-corneal tear film in the dog. The majority of the animals were found to have high levels of ocular surface contamination by particulate material and plaques of viscous mucus. Other abnormalities included surface lipid with an abnormal granular (three dogs) or 'curdled' (two dogs) appearance; excessive thinning of the lipid layer of the tear film; and the presence of dark globular structures in two dogs, which were presumed to be abnormal meibomian lipid. Break up of the tear film was observed in one dog. Grossly, a thread of viscous mucus was frequently observed along the margin of the lower eyelid. It is postulated that this thread forms because of the excessively exophthalmic conformation of the breed, which prevents the normal access of effete mucus and entrapped debris to the lower conjunctival fornix. The combination of the above factors in the pekingese is suggested as the mechanism whereby the tear film has a reduced stability, thus enhancing the risk from factors more usually considered to initiate corneal ulceration in the breed. The possible adverse effects of lid splitting for the mass removal of distichiae in exophthalmic dogs is discussed. 相似文献
2.
Michelle S Schulte Agnes E Rupley 《Veterinary Clinics of North America: Exotic Animal Practice》2004,7(2):315-50, vi-vii
Birds are becoming more popular as pets, and the need for veterinary professionals to learn more about these pets is crucial. This article introduces the veterinary staff to basic information required to provide high-quality care to avian patients. High-quality nutrition for a variety of species and ages is included in this article. The importance of proper husbandry and intellectual stimulation with toys is also discussed. Special emphasis is placed on instructions for clients when making appointments, as well as recognizing signs of illness for both clients and veterinary staff. Capture, restraint, and sample collection are an important part of this article, as well as medication administration, anesthesia, supportive care, preventive care and grooming. A variety of aspects concerning the care of the avian patient are covered for the benefit of the client and veterinary technician. 相似文献
3.
4.
In vitro evaluation of a simulated pneumoperitoneum environment using carbon dioxide on canine transitional cell carcinoma 下载免费PDF全文
5.
6.
7.
8.
Kelsey T. Young Kevin K. Lahmers Holly S. Sellers David E. Stallknecht Rebecca L. Poulson Jerry T. Saliki Stephen Mark Tompkins Ian Padykula Chris Siepker Elizabeth W. Howerth Michelle Todd James B. Stanton 《Journal of veterinary diagnostic investigation》2021,33(2):202
RNA viruses rapidly mutate, which can result in increased virulence, increased escape from vaccine protection, and false-negative detection results. Targeted detection methods have a limited ability to detect unknown viruses and often provide insufficient data to detect coinfections or identify antigenic variants. Random, deep sequencing is a method that can more fully detect and characterize RNA viruses and is often coupled with molecular techniques or culture methods for viral enrichment. We tested viral culture coupled with third-generation sequencing for the ability to detect and characterize RNA viruses. Cultures of bovine viral diarrhea virus, canine distemper virus (CDV), epizootic hemorrhagic disease virus, infectious bronchitis virus, 2 influenza A viruses, and porcine respiratory and reproductive syndrome virus were sequenced on the MinION platform using a random, reverse primer in a strand-switching reaction, coupled with PCR-based barcoding. Reads were taxonomically classified and used for reference-based sequence building using a stock personal computer. This method accurately detected and identified complete coding sequence genomes with a minimum of 20× coverage depth for all 7 viruses, including a sample containing 2 viruses. Each lineage-typing region had at least 26× coverage depth for all viruses. Furthermore, analyzing the CDV sample through a pipeline devoid of CDV reference sequences modeled the ability of this protocol to detect unknown viruses. Our results show the ability of this technique to detect and characterize dsRNA, negative- and positive-sense ssRNA, and nonsegmented and segmented RNA viruses. 相似文献
9.
Rhinoceros populations in Africa are under severe threat as a result of surging poaching rates and risk-mitigation strategies are continuously adapted in an attempt to ensure the survival of the species. This study compared faecal glucocorticoid metabolite (fGCM) levels of two age classes of limited free-ranging female white rhinos with fGCM levels of adult free-ranging female white rhinos. Subsequently, fGCM alterations in the limited free-ranging animals were monitored following routine dehorning as a measure of the animals’ short-term physiological stress response. Baseline fGCM levels differed significantly between tested groups, with both free-ranging and limited free-ranging adult animals showing significantly higher fGCM levels compared with limited free-ranging juvenile females. In contrast, baseline fGCM levels did not differ significantly between limited free-ranging and free-ranging adult individuals. Routine dehorning procedures resulted in a short-term stress response expressed by a significant increase in fGCM levels 48 h post-dehorning, with stress steroid levels returning to pre-dehorning concentrations 72 h after the procedure. 相似文献
10.