全文获取类型
收费全文 | 449篇 |
免费 | 41篇 |
专业分类
林业 | 26篇 |
农学 | 7篇 |
基础科学 | 3篇 |
70篇 | |
综合类 | 38篇 |
农作物 | 22篇 |
水产渔业 | 38篇 |
畜牧兽医 | 254篇 |
园艺 | 8篇 |
植物保护 | 24篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 13篇 |
2021年 | 20篇 |
2020年 | 16篇 |
2019年 | 22篇 |
2018年 | 26篇 |
2017年 | 18篇 |
2016年 | 15篇 |
2015年 | 12篇 |
2014年 | 20篇 |
2013年 | 26篇 |
2012年 | 32篇 |
2011年 | 32篇 |
2010年 | 20篇 |
2009年 | 15篇 |
2008年 | 26篇 |
2007年 | 31篇 |
2006年 | 21篇 |
2005年 | 26篇 |
2004年 | 24篇 |
2003年 | 23篇 |
2002年 | 10篇 |
2001年 | 11篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1984年 | 2篇 |
1981年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有490条查询结果,搜索用时 15 毫秒
81.
Marco L. Margiocco DMV MS Jamie Warren DVM Michele Borgarelli DMV PhD Butch Kukanich DVM PhD 《Journal of Veterinary Cardiology》2009,11(1):31-39
Objectives
Congenital and acquired cardiac disorders are frequently diagnosed in small breed dogs and cats. In order to appropriately dose cardiovascular drugs for small patients, fractions of commercially available tablets must be prescribed. The aims of this study were to evaluate weight and content uniformity and 30-day chemical stability in halves and quarters of 11 drug formulations commonly prescribed to treat cardiovascular disorders in small breed dogs and cats.Animals, materials and methods
Fifteen tablets from 11 drug formulations were obtained within the same lot. Tablets were split by a single operator using a commercially available pill splitter. Whole tablets, halves and quarters were weighed and stored in plastic containers. High-pressure liquid chromatography or liquid chromatography with mass spectrometry were utilized to determine drug content and repeated 30 days later to estimate chemical stability.Results
Statistically significant weight variability, content non-uniformity and chemical degradation were found for some formulations. Digoxin showed a significant degradation that should be considered in clinical practice.Conclusions
It appears that pill splitting is overall a relatively reliable practice; however tablets should not be split ahead of time but only immediately prior to intended usage. 相似文献82.
Pedunculate oak forests (Quercus robur L.) in the Ticino Regional Park, Italy, are declining as a result of insect attacks, summer droughts and air pollution. The assessment and monitoring of forest condition can provide a basis for managing and conserving forest ecosystems and thereby avoid loss of valuable natural resources. Currently, most forest assessments are limited to ground-based visual evaluations that are local and subjective. It is therefore difficult to compare data collected by different crews or to define reliable trends over years. We examined vegetation variables that can be quantitatively estimated by remote observations and, thus, are suitable for objective monitoring over extended forested areas. We found that total chlorophyll (Chl) concentration is the most suitable variable for assessing pedunculate oak decline. It is highly correlated with visual assessments of discoloration. Furthermore, Chl concentration can be accurately estimated from leaf optical properties, making it feasible to map Chl concentration at the canopy level from satellite and airborne remote observations. 相似文献
83.
Annual survival probabilities of juvenile loggerhead sea turtles indicate high anthropogenic impact on Mediterranean populations
下载免费PDF全文
![点击此处可从《水产资源保护:海洋与淡水生态系统》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Paolo Casale Daniela Freggi Giovanni Furii Carola Vallini Pasquale Salvemini Michele Deflorio Giovanni Totaro Stefano Raimondi Caterina Fortuna Brendan J. Godley 《水产资源保护:海洋与淡水生态系统》2015,25(5):690-700
- 相似文献
84.
Synthesis,theoretical studies,and effect on the photosynthetic electron transport of trifluoromethyl arylamides
下载免费PDF全文
![点击此处可从《Pest management science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
85.
Jose V. Moris Giorgio Vacchiano Simone Ravetto Enri Michele Lonati Renzo Motta Davide Ascoli 《New Forests》2017,48(5):663-683
European larch is a dominant species in the subalpine belt of the western Alps. Despite recent increases in wildfire activity in this region, fire ecology of European larch is poorly understood compared to other larch species around the world. This study aims to assess whether European larch forests are resilient to fires, and to find out the factors that drive such resilience. We assessed the recovery of larch forests along a gradient of fire severity (low, moderate, high) based on the abundance and dominance of post-fire larch regeneration. We established 200 plots distributed among burned larch forests in nine wildfires that occurred between 1973 and 2007 in the western Alps. We included variables regarding topography, climate, fire severity, fire legacies, ground cover, grazing intensity, and time since fire. To evaluate potential drivers of larch recruitment, we applied generalized linear mixed models (GLMM) and random forests (RF). Larch regeneration was much more abundant and dominant in the moderate- and high-severity fire classes than in the low-severity class. More than half of the plots in the moderate- and high-severity classes were classified as resilient, i.e., post-fire larch regeneration was enough to recover a larch stand. GLMM and RF produced complementary results: fire severity and legacies, such as snags, canopy cover and distance to seed source, were crucial factors explaining post-fire larch recruitment. This study shows that fire has a positive effect on larch regeneration, and we conclude that European larch forests are highly resilient to mixed-severity fires in the western Alps. 相似文献
86.
Aeroz™ (9,10-anthraquinone (AQ)), a chemical rice seed treatment that effectively deters birds from depredating newly planted fields, could be an important management tool that enables rice producers to plant earlier in the season and increase yields. This bird repellent, while non-lethal to birds, has unknown toxicity to crayfish that often are closely integrated with rice production in southern regions of the USA. This study was conducted to assess if AQ, the active ingredient in Aeroz™, could be acutely toxic to the red swamp crayfish Procambarus clarkii (Girard), the crayfish species most often associated with rice cultivation, via seed ingestion and/or through their contact with chemical in pond water. Mortality data from a 96 h feeding study indicate that AQ-treated (1.76% by wt) rice seed was not acutely toxic to juvenile (∼3 mo.) crayfish through the ingestion exposure route. In addition, a 96 h aquatic acute toxicity test showed that the LC50 of AQ in juvenile crayfish is >85 μg L−1 and above the water solubility limit of AQ. These results indicate that very minimal, if any, acute toxicity would be observed in juvenile crayfish if exposed to AQ via ingestion or dissolved or suspended in the water column. 相似文献
87.
Mulching and/or topsoil incorporation of plant residues from green manure legumes can increase cropping system sustainability, and can supply and retain nutrients. Two field experiments were conducted in Italy over the period of 2006–2007, to investigate the effect of faba bean grown in a temperate environment to fruit morphology, quality and chemical composition of the subsequent melon (Cucumis melo L.) crop. Flowering faba bean plants were managed as mulch on the melon plant rows and cut and incorporated into the soil, in comparison with cultivated soil (control) and black plastic mulch. 相似文献
88.
89.
Bommarito DA Lattimer JC Selting KA Henry CJ Cohen M Johnson GC 《Journal of the American Animal Hospital Association》2011,47(6):e188-e194
A 12 yr old castrated male Yorkshire terrier was presented with a history of an inoperable pheochromocytoma. Physical examination revealed a large, midabdominal mass. Neurologic examination was normal at presentation. An abdominal computed tomography scan revealed a 215 cm(3) mass in the region of the right kidney. Forty-eight hours after IV injection of 370 megabecquerels (MBq, equivalent to10 millicuries [mCi]) of metaiodobenzylguanidine labeled with radioactive iodine ([(131)I]MIBG), standard planar scintigraphy was performed. A diffuse area of moderate uptake was noted in the midabdominal region. The dog experienced stable disease for 1.5 mo after injection based on a follow-up computed tomography (CT) scan; however, 5 mo after injection, repeat CT imaging revealed progression of the tumor, and a second IV injection of 370 MBq (10 mCi) of [(131)I]MIBG was administered. The dog died 3 wk after the second injection as a result of gastrointestinal blood loss that was believed to be caused by compression-induced bowel ischemia by the mass. A full necropsy was not performed, but the mass was removed for histologic evaluation, which confirmed the diagnosis of pheochromocytoma. This report is the first to document the treatment of canine pheochromocytoma using [(131)I]MIBG. 相似文献
90.
Berlanda M Zotti A Brandazza G Poser H Calò P Bernardini M 《The Canadian veterinary journal. La revue veterinaire canadienne》2011,52(12):1334-1338
Magnetic resonance and computed tomography features of 4 cases of canine congenital vertebral anomalies (CVAs) are discussed. Two of the cases represent unusual presentations for such anomalies that commonly affect screw-tail or toy breeds. Moreover, the combination of CVAs and a congenital peritoneo-pericardial diaphragmatic hernia has never before been imaged. 相似文献