全文获取类型
收费全文 | 6274篇 |
免费 | 323篇 |
国内免费 | 4篇 |
专业分类
林业 | 450篇 |
农学 | 196篇 |
基础科学 | 37篇 |
1184篇 | |
综合类 | 964篇 |
农作物 | 254篇 |
水产渔业 | 373篇 |
畜牧兽医 | 2513篇 |
园艺 | 207篇 |
植物保护 | 423篇 |
出版年
2023年 | 42篇 |
2022年 | 64篇 |
2021年 | 103篇 |
2020年 | 163篇 |
2019年 | 168篇 |
2018年 | 162篇 |
2017年 | 151篇 |
2016年 | 158篇 |
2015年 | 130篇 |
2014年 | 162篇 |
2013年 | 295篇 |
2012年 | 369篇 |
2011年 | 455篇 |
2010年 | 261篇 |
2009年 | 192篇 |
2008年 | 371篇 |
2007年 | 363篇 |
2006年 | 333篇 |
2005年 | 316篇 |
2004年 | 306篇 |
2003年 | 305篇 |
2002年 | 292篇 |
2001年 | 71篇 |
2000年 | 73篇 |
1999年 | 87篇 |
1998年 | 62篇 |
1997年 | 57篇 |
1996年 | 59篇 |
1995年 | 43篇 |
1994年 | 56篇 |
1993年 | 51篇 |
1992年 | 42篇 |
1991年 | 50篇 |
1990年 | 48篇 |
1989年 | 43篇 |
1988年 | 39篇 |
1987年 | 40篇 |
1986年 | 54篇 |
1985年 | 33篇 |
1984年 | 44篇 |
1983年 | 35篇 |
1982年 | 36篇 |
1981年 | 27篇 |
1980年 | 20篇 |
1979年 | 23篇 |
1978年 | 27篇 |
1977年 | 26篇 |
1975年 | 20篇 |
1973年 | 24篇 |
1972年 | 20篇 |
排序方式: 共有6601条查询结果,搜索用时 31 毫秒
41.
42.
43.
44.
45.
Thomas R. De Ridder Justine E. Campbell Cheryl Burke‐Schwarz David Clegg Emily L. Elliot Samuel Geller Wendy Kozak Stephen T. Pittenger Jennifer B. Pruitt Jocelyn Riehl Julie White Melissa L. Wiest Chad M. Johannes John Morton Pamela D. Jones Peter F. Schmidt Victoria Gordon Paul Reddell 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2021,35(1):415-429
46.
In this study the starch digestion rates in broiler chickens from 18 samples of 5 commonly used feed grains (sorghum, wheat, maize, barley, triticale) were determined. The methodology to determine starch digestion rates in poultry is detailed herein. Starch digestion rates were not significantly different (P = 0.128) across the 18 feed grains, which reflects the wide variations that were observed within a given feedstuff. Nevertheless, starch digestion rates in broiler chickens offered wheat-based diets were significantly more rapid by 56.0% (0.117 versus 0.075 min−1; P = 0.012) than their sorghum-based counterparts on the basis of a pair-wise comparison. In descending order, the following starch digestion rates were observed: wheat (0.117 min−1), barley (0.104 min−1), triticale (0.093 min−1), maize (0.086 min−1), sorghum (0.075 min−1). The implications of these findings are discussed as they almost certainly have implications for poultry nutrition and the development of reduced crude protein diets for broiler chickens. 相似文献
47.
CORRELATIONS AMONG ULTRASONOGRAPHIC MEASUREMENTS OF OPTIC NERVE SHEATH DIAMETER,AGE, AND BODY WEIGHT IN CLINICALLY NORMAL HORSES
下载免费PDF全文
![点击此处可从《Veterinary radiology & ultrasound》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Stacy D. Cooley Peter V. Scrivani Margret S. Thompson Nita L. Irby Thomas J. Divers Hollis N. Erb 《Veterinary radiology & ultrasound》2016,57(1):49-57
Early diagnosis of high intracranial pressure (ICP) is critical for minimizing progressive brain injury due to reduced cerebral perfusion. In people, detecting enlargement of the optic nerve sheath diameter (ONSD) by transpalpebral ultrasonography has been found to be an accurate test for high ICP. Aims of this prospective, observational, cross‐sectional study were to test hypotheses that (1) ultrasonographic measurement of ONSD would be repeatable in horses, (2) have acceptable interobserver agreement, and (3) would be correlated with age and body weight. The sample population included 48 horses without clinical signs of high ICP and with varying ages and body weights. Two observers independently performed ONSD measurements in both eyes. All measurements ranged from 2.6 to 6.5 mm. The mean difference of repeated measures within observers was ≤0.1 mm and the coefficients of variation ranged from 5.0% to 8.8%. The mean difference of measures between observers was ≤0.2 mm. After correcting for performing multiple tests, no significant rank correlation (all r < 0.4 [absolute value]) was detected between ONSD and age or body weight. However, we observed smaller ONSD in foals versus adults (all P ≤ 0.002). In the foals, all observed measures of rostrocaudal and dorsoventral ONSD were <5 mm. In the adults, all observed measures of rostrocaudal and dorsoventral ONSD were ≤6.5 mm. Findings indicated that ultrasonographic ONSD measurement is a feasible test for use in horses of varying ages and sizes. Further investigation of this ultrasonographic measure as a clinical test for horse with suspected high ICP is warranted. 相似文献
48.
49.
50.