全文获取类型
收费全文 | 3484篇 |
免费 | 133篇 |
国内免费 | 4篇 |
专业分类
林业 | 215篇 |
农学 | 103篇 |
基础科学 | 22篇 |
629篇 | |
综合类 | 492篇 |
农作物 | 177篇 |
水产渔业 | 286篇 |
畜牧兽医 | 1384篇 |
园艺 | 105篇 |
植物保护 | 208篇 |
出版年
2023年 | 21篇 |
2022年 | 22篇 |
2021年 | 63篇 |
2020年 | 64篇 |
2019年 | 71篇 |
2018年 | 64篇 |
2017年 | 70篇 |
2016年 | 85篇 |
2015年 | 48篇 |
2014年 | 86篇 |
2013年 | 129篇 |
2012年 | 150篇 |
2011年 | 237篇 |
2010年 | 108篇 |
2009年 | 99篇 |
2008年 | 190篇 |
2007年 | 213篇 |
2006年 | 223篇 |
2005年 | 209篇 |
2004年 | 209篇 |
2003年 | 198篇 |
2002年 | 191篇 |
2001年 | 42篇 |
2000年 | 41篇 |
1999年 | 41篇 |
1998年 | 53篇 |
1997年 | 53篇 |
1996年 | 48篇 |
1995年 | 38篇 |
1994年 | 36篇 |
1993年 | 30篇 |
1992年 | 34篇 |
1991年 | 33篇 |
1990年 | 37篇 |
1989年 | 31篇 |
1988年 | 22篇 |
1987年 | 22篇 |
1986年 | 17篇 |
1985年 | 29篇 |
1984年 | 19篇 |
1983年 | 25篇 |
1982年 | 23篇 |
1981年 | 21篇 |
1980年 | 19篇 |
1978年 | 18篇 |
1977年 | 12篇 |
1975年 | 16篇 |
1974年 | 16篇 |
1967年 | 8篇 |
1966年 | 7篇 |
排序方式: 共有3621条查询结果,搜索用时 15 毫秒
21.
22.
Bryan M. Waldridge Allison J. Stewart Debra C. Taylor William J. Saville 《Journal of Equine Veterinary Science》2011,31(12):700-702
Aeromonas species have been isolated from the feces of diarrheic adult horses and foals. However, Aeromonas species have also been isolated from the feces of approximately 5% of clinically normal adult horses outside the United States. The objectives of this study were to determine whether Aeromonas species can be shed in the feces of nondiarrheic adult horses and identify any effects of season of year, transportation, and hospitalization on possible fecal shedding of Aeromonas species. Feces were cultured for Aeromonas and Salmonella species from 138 nondiarrheic adult horses examined in the hospital and by field services for complaints other than gastrointestinal disease. Fecal Aeromonas and Salmonella species were isolated from 6.5% and 2.2% of nondiarrheic horses, respectively. All Aeromonas isolates were identified as A caviae. There were no apparent effects on time of year, hospitalization, or transport on isolation of Aeromonas species from feces. Isolation of Aeromonas species from diarrheic horses in the absence of other possible enteric pathogens indicates intestinal disease as a result of Aeromonas infection, but Aeromonas species can also occur as copathogens with Salmonella infections. 相似文献
23.
植酸酶是一种功能强大的酶,能够使无法消化利用的饲料释放出大量的养分。
但当植酸酶使用不当时,那些养分将不能被释放出和/或被动物机体所获取。如果那样,植酸酶的投入成本和价值就将被浪费了。 相似文献
24.
Shanon M. Zabolotzky Karen M. Vernau Philip H. Kass William Vernau 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2010,39(1):90-95
Background: Myelin‐like material in canine cerebrospinal fluid (CSF) specimens has been attributed to demyelinating or myelomalacic conditions. In our experience, myelin‐like material is observed frequently, especially in lumbar samples, and in a variety of disease conditions. Objectives: The objective of this study was to determine if there are associations between the presence of myelin‐like material and CSF collection site, body weight, underlying disease, and patient outcome. Methods: Wright–Giemsa‐stained cytocentrifuged specimens of CSF from the cerebellomedullary cistern (n=51) and lumbar cistern (n=47) of 98 dogs with neurologic disease were evaluated retrospectively for the presence and amount of extracellular myelin‐like material. Results were compared based on collection site, body weight, type of neurologic disease, and outcome. Results: Myelin‐like material was observed in 20/98 (20%) samples and was more frequently observed in lumbar (17/47, 36%) than cerebellomedullary samples (3/51, 6%) (P=.0028). Samples from dogs <10 kg were more likely to contain myelin (14/36, 39%) compared with dogs ≥10 kg (5/60, 8%) (P=.0052). Larger amounts of myelin‐like material were observed in CSF from dogs with intervertebral disk disease compared with other diseases (P=.045). No association was found between myelin‐like material and outcome. Conclusion: The association of extracellular myelin‐like material in canine CSF samples with sampling site and body weight suggests it is more often an artifact of collection technique and anatomy rather than the result of neurologic disease. Myelin‐like material in CSF is not associated with a poorer prognosis. 相似文献
25.
26.
Regina Campbell-Malone Susan G Barco Pierre-Yves Daoust Amy R Knowlton William A McLellan David S Rotstein Michael J Moore 《Journal of zoo and wildlife medicine》2008,39(1):37-55
Vessel-whale collision events represented the ultimate cause of death for 21 (52.5%) of the 40 North Atlantic right whales (Eubalaena glacialis) necropsied between 1970 and December 2006. Injuries seen in vessel-struck whales fall into two distinct categories: 1) sharp trauma, often resulting from contact with the propeller, and 2) blunt trauma, presumably resulting from contact with a vessel's hull. This study analyzes four trauma cases that resulted from vessel-whale collisions, which together provide a framework for a more critical understanding of lethal blunt and sharp trauma resulting from vessel collisions with right whales. In case no. 1, contact with a propeller resulted in three deep lacerations. The animal survived acute trauma only to succumb nearly 14 years later when the lesions reopened and became infected. In case no. 2, anecdotal reports linked the laceration of large arteries of the peduncle and histologic evidence of perimortem trauma at a bone fracture site to vessel-whale collision trauma. Case no. 3 had a laceration of the oral rete and a fracture of the rostrum. Both of the areas displayed histologic evidence of perimortem blunt trauma. Finally, in case no. 4, an antemortem mandibular fracture, two additional skull fractures, and widespread hemorrhage were consistent with severe blunt trauma. Evidence from each case, including the timing of trauma relative to the time of death and identifying characteristics of both trauma types, are presented. Before this study, no detailed comparative analysis of trauma pathology that resulted from lethal interactions between vessels and right whales had been conducted. This study demonstrates the importance of detailed gross and histologic examination in determining the significance and timing of traumatic events. This work represents a new paradigm for the differential diagnosis of lethal sharp and blunt trauma in right whales hit by ships and will enhance the present understanding of the impact of anthropogenic mortality on this critically endangered species. 相似文献
27.
28.
Lascelles BD Thomson MJ Dernell WS Straw RC Lafferty M Withrow SJ 《Journal of the American Animal Hospital Association》2003,39(3):294-305
This paper describes in detail a combined dorsal and intraoral approach for maxillectomy for tumors involving tissues more caudal to the third premolar. The only intraoperative complication was that of blood loss, with six out of 20 dogs requiring a single unit of blood. Histopathologically clean margins were obtained in 14 of the 20 cases, with a recurrence rate of 50% in these dogs and a median time to recurrence of 24 months. This represents an improvement in outcome over previously reported studies, and the authors postulate this is due to the better exposure and access to the area afforded by the combined approach over the standard intraoral approach. 相似文献
29.
30.