全文获取类型
收费全文 | 926篇 |
免费 | 61篇 |
专业分类
林业 | 76篇 |
农学 | 19篇 |
基础科学 | 10篇 |
180篇 | |
综合类 | 117篇 |
农作物 | 26篇 |
水产渔业 | 95篇 |
畜牧兽医 | 367篇 |
园艺 | 17篇 |
植物保护 | 80篇 |
出版年
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 13篇 |
2020年 | 13篇 |
2019年 | 20篇 |
2018年 | 14篇 |
2017年 | 15篇 |
2016年 | 34篇 |
2015年 | 23篇 |
2014年 | 25篇 |
2013年 | 50篇 |
2012年 | 47篇 |
2011年 | 68篇 |
2010年 | 40篇 |
2009年 | 30篇 |
2008年 | 57篇 |
2007年 | 55篇 |
2006年 | 60篇 |
2005年 | 64篇 |
2004年 | 44篇 |
2003年 | 58篇 |
2002年 | 49篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 15篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1967年 | 3篇 |
1959年 | 5篇 |
1958年 | 2篇 |
排序方式: 共有987条查询结果,搜索用时 312 毫秒
31.
Ben C Maddison John Spiropoulos Christopher M Vickery Richard Lockey Jonathan P Owen Keith Bishop Claire A Baker Kevin C Gough 《Veterinary research》2015,46(1)
Ovine scrapie can be transmitted via environmental reservoirs. A pool of ovine scrapie isolates were incubated on soil for one day or thirteen months and eluted prion was used to challenge tg338 mice transgenic for ovine PrP. After one-day incubation on soil, two PrPSc phenotypes were present: G338 or Apl338ii. Thirteen months later some divergent PrPSc phenotypes were seen: a mixture of Apl338ii with either G338 or P338, and a completely novel PrPSc deposition, designated Cag338. The data show that prolonged ageing of scrapie prions within an environmental matrix may result in changes in the dominant PrPSc biological/biochemical properties. 相似文献
32.
Clinical,histopathological and immunohistochemical characterization of a novel equine ocular disorder: heterochromic iridocyclitis with secondary keratitis in adult horses 下载免费PDF全文
33.
Tom MISSELBROOK Zhaohai BAI Zejiang CAI Weidong CAO Alison CARSWELL Nicholas COWAN Zhenling CUI David CHADWICK Bridget EMMETT Keith GOULDING Rui JIANG Davey JONES Xiaotang JU Hongbin LIU Yuelai LU Lin MA David POWLSON Robert M. REES Ute SKIBA Pete SMITH Roger SYLVESTER-BRADLEY John WILLIAMS Lianhai WU Minggang XU Wen XU Fusuo ZHANG Junling ZHANG Jianbin ZHOU Xuejun LIU 《农业科学与工程前沿(英文版)》2022,9(3):475
34.
- 1. The coastal waters surrounding Britain and Ireland became warmer during the 20th century and, according to the UK Climate Impact Programme 2002 scenarios of change and other sources, average annual seawater temperatures may rise a further 2°C or more by the 2050s. This warming is part of a global rise in sea‐ and air‐surface temperatures that will cause changes in the distribution and abundance of species.
- 2. Initially, there will not be a wholesale movement northwards of southern species or retreat northwards of northern species, because many additional factors will influence the responses of the different organisms. Such factors include the hydrodynamic characteristics of water masses, the presence of hydrographical and geographical barriers to spread and the life history characteristics (reproductive mode, dispersal capability and longevity) of species. Survey data over the past century show how organisms react to changes of the order of 0.5°C, and in the last two decades, when sea temperatures have risen by as much as 1°C, there have been significant local changes in the distribution of intertidal organisms. These past changes provide a clue to more extensive changes expected in the future if global warming develops as predicted.
- 3. Where species affected by climate change are dominant or key structural or functional species in biotopes, there may be a change in the extent and distribution of those biotopes. Some, dominated by predominantly northern species such as the horse mussel Modiolus modiolus, may decline and reduce their value as rich habitats for marine life. Others, characterized by southern species, for example the sea fan Eunicella verrucosa and the alcyonacean Alcyonium glomeratum, may increase in extent.
- 4. Using information on the life history characteristics of species, their present distribution and other factors, a key supported by a decision tree has been constructed to identify ‘types’ of organism according to their likely response to temperature rise. Conspicuous and easily identified rocky substratum species are good candidates to track change. Using the key, many species are shown as likely to increase their range northwards significantly. In contrast, fewer will decline in abundance and extent in the north. If, as anticipated, global warming continues, then species with distributions already accurately mapped, or being mapped at present, will provide baseline data to test forecasts.
35.
36.
37.
38.
Nicole L. Vollmer Patricia E. Rosel Keith D. Mullin Lori H. Schwacke Lance P. Garrison Brian C. Balmer Kevin Barry Anthony Martinez Brian M. Quigley Carrie Sinclair Todd R. Speakman Jesse Wicker Lynsey Wilcox Eric S. Zolman 《水产资源保护:海洋与淡水生态系统》2021,31(10):2951-2966
- Population structure of highly mobile marine organisms can be complex and difficult to study, but it is important to understand how populations partition themselves within their environment for accurate assessment of both natural and anthropogenic impacts and successful management. The 2010 Deepwater Horizon oil spill negatively impacted common bottlenose dolphins (Tursiops truncatus) within Mississippi Sound and the surrounding north central Gulf of Mexico (GOMx); however, little was known about their underlying population structure in these waters. Thus, it was unclear how many demographically independent populations were affected by the spill.
- Common bottlenose dolphin samples were collected throughout inshore waters of Mississippi Sound and coastal waters of the north-central GOMx. Mitochondrial DNA control region sequence data and 19 nuclear microsatellite loci were analysed to determine how many populations are present and characterize their range throughout these waters.
- Bayesian clustering and migration analyses identified two genetically distinct and demographically independent populations: one predominantly inhabiting Mississippi Sound and adjacent coastal waters, and a second population extending generally from offshore of Mobile Bay, Alabama, east along the Florida Panhandle. Neither of these populations align with the currently delineated management stocks previously used to estimate impacts from the oil spill on common bottlenose dolphins in this portion of the GOMx.
- These results suggest that revisions may be necessary so that management stocks accurately represent the demographically independent populations present in these waters. Furthermore, better comprehension of underlying population structure will enhance impact assessments on common bottlenose dolphins and provide more appropriate baseline data to support future restoration and conservation objectives.
39.
Keith L Bailey Michael J Kinsel Kathy A Connell 《Journal of veterinary diagnostic investigation》2003,15(5):454-456
Multiple cutaneous masses developed in the perineum of a 14-year-old Saddlebred stallion over a period of approximately 5 years. Clinically, the masses ranged in size from 3- to 9-mm diameter and were not ulcerated, painful, or pruritic. Three of the masses were surgically excised and submitted for microscopic evaluation. The masses were dome shaped to nodular, located in the superficial dermis, and composed of haphazardly arranged bundles of plump spindle-shaped cells. The tumor cells immunoreacted with monoclonal antibodies directed against desmin, muscle-specific actin, and smooth muscle actin, confirming a smooth muscle origin. Multiple cutaneous leiomyomas have not been reported previously in horses. 相似文献
40.
John M Kreeger Alison Templer Susan E Tumquist Keith L Bailey Philip J Johnson David A Wilson 《Journal of veterinary diagnostic investigation》2002,14(4):322-325
Paranasal meningioma was diagnosed in a 5-year-old Appaloosa gelding. The mass occupied the right maxillary, frontal, and sphenopalatine sinuses but did not invade the calvarium. The diagnosis was based on histologic evaluation, positive immunohistochemical staining for vimentin and cytokeratin, and ultrastructural features including the presence of interdigitating spindle cells with numerous desmosomes. 相似文献