全文获取类型
收费全文 | 1324篇 |
免费 | 80篇 |
国内免费 | 33篇 |
专业分类
林业 | 41篇 |
农学 | 31篇 |
基础科学 | 12篇 |
154篇 | |
综合类 | 250篇 |
农作物 | 142篇 |
水产渔业 | 46篇 |
畜牧兽医 | 696篇 |
园艺 | 25篇 |
植物保护 | 40篇 |
出版年
2023年 | 17篇 |
2022年 | 14篇 |
2021年 | 27篇 |
2020年 | 23篇 |
2019年 | 51篇 |
2018年 | 25篇 |
2017年 | 43篇 |
2016年 | 24篇 |
2015年 | 29篇 |
2014年 | 50篇 |
2013年 | 58篇 |
2012年 | 71篇 |
2011年 | 65篇 |
2010年 | 57篇 |
2009年 | 47篇 |
2008年 | 74篇 |
2007年 | 60篇 |
2006年 | 58篇 |
2005年 | 57篇 |
2004年 | 36篇 |
2003年 | 30篇 |
2002年 | 33篇 |
2001年 | 39篇 |
2000年 | 38篇 |
1999年 | 29篇 |
1998年 | 15篇 |
1997年 | 9篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1992年 | 17篇 |
1991年 | 15篇 |
1990年 | 22篇 |
1989年 | 20篇 |
1988年 | 15篇 |
1986年 | 10篇 |
1985年 | 14篇 |
1984年 | 11篇 |
1983年 | 14篇 |
1982年 | 6篇 |
1980年 | 9篇 |
1979年 | 13篇 |
1978年 | 7篇 |
1975年 | 7篇 |
1974年 | 7篇 |
1973年 | 11篇 |
1972年 | 6篇 |
1971年 | 12篇 |
1970年 | 13篇 |
1968年 | 8篇 |
1966年 | 8篇 |
排序方式: 共有1437条查询结果,搜索用时 31 毫秒
61.
62.
从一个经典的动态不完全信息信号博弈模型的视角分析当前中国股票市场解禁的非流通股股东与现存普通流通股东的博弈行为,结果表明:当前针对大小非减持的信息披露机制有其积极意义;同时我国股票市场会发生一些重大变化.特别是价值发现功能和经济睛雨表的功能将逐步增强. 相似文献
63.
64.
Kendal E Harr Kathryn Allison Robert K Bonde David Murphy John W Harvey 《Journal of zoo and wildlife medicine》2008,39(2):180-187
Muscle injury is common in Florida manatees (Trichechus manatus latirostris). Plasma aspartate aminotransferase (AST) is frequently used to assess muscular damage in capture myopathy and traumatic injury. Therefore, accurate measurement of AST and alanine aminotransferase (ALT) is important in managed, free-ranging animals, as well as in those rehabilitating from injury. Activities of these enzymes, however, are usually not increased in manatees with either acute or chronic muscle damage, despite marked increases in plasma creatine kinase activity. It is hypothesized that this absence of response is due to apoenzymes in the blood not detected by commonly used veterinary assays. Addition of coenzyme pyridoxal-5-phosphate (P5P or vitamin B6) should, therefore, result in higher measured enzyme activities. The objective of this study was to determine the most accurate, precise, and diagnostically useful method for aminotransferase measurement in manatees that can be used in veterinary practices and diagnostic laboratories. Additionally, appropriate collection and storage techniques were assessed. The use of an optimized commercial wet chemical assay with 100 micromol P5P resulted in a positive bias of measured enzyme activities in a healthy population of animals. However, AST and ALT were still much lower than that typically observed in domestic animals and should not be used alone in the assessment of capture myopathy and muscular trauma. Additionally, the dry chemistry analyzer, typically used in clinics, reported significantly higher and less precise AST and ALT activities with poor correlation to those measured with wet chemical methods found in diagnostic laboratories. Therefore, these results cannot be clinically compared. Overall, the optimized wet chemical method was the most precise and diagnostically useful measurement of aminotransferase in samples. Additionally, there was a statistically significant difference between paired serum and plasma measurement, indicating that separate reference intervals should be established for serum and plasma. Finally, storage of these enzymes at -70 degrees C for 1 mo resulted in up to a 25% decrease in enzymatic activity in manatee plasma. 相似文献
65.
66.
西藏野生动物资源及其监测体系的探讨 总被引:1,自引:0,他引:1
结合西藏2000年野生动物资源监测调查,对监测调查结果进行了分析与评价,在此基础上,对建立西藏野生动物资源监测体系进行了探讨。 相似文献
67.
Summary Several factors which influence the treatment of timber products with vapour phase preservatives such as borate esters are considered. Gas flow rate through the substrate was found to be a significant factor limiting both preservative penetration and its rate of deposition. A theoretical model of the treatment process was developed and tested experimentally to determine the influence of several factors on the retention and distribution of boric acid. Gas flow into the timber product was influenced by permeability, pressure gradient and substrate moisture content. The implications of the findings are considered with regard to the treatment of wood and wood products with gaseous reagents.The authors wish to thank the following for their financial support and interest in this research programme — Rentokil Ltd, Rhone-Poulenc/Manchem Ltd, Forestry Commission, UK and Ireland Particleboard Association (now Panel Products Association), Norbord Highland plc (formerly Highland Forest Products plc), IMPEL 相似文献
68.
69.
Surgical correction of gastro‐oesophageal intussusception with bilateral incisional gastropexy in three dogs
下载免费PDF全文
![点击此处可从《The Journal of small animal practice》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Three dogs presented for evaluation of acute onset tachypnoea and dyspnoea following episodes of vomiting and/or regurgitation. Thoracic radiographs were suggestive of a gastro‐oesophageal intussusception in all three dogs; one dog also showed evidence of aspiration pneumonia. All three dogs underwent surgical correction with a bilateral incisional gastropexy. All dogs recovered from anaesthesia uneventfully and were discharged from the hospital 3 days after presentation. Persistent megaoesophagus was evident in all three dogs, and they are being chronically managed with a strict feeding regime and pro‐motility agents. 相似文献
70.