全文获取类型
收费全文 | 144993篇 |
免费 | 8219篇 |
国内免费 | 89篇 |
专业分类
林业 | 6309篇 |
农学 | 4611篇 |
基础科学 | 997篇 |
18141篇 | |
综合类 | 24108篇 |
农作物 | 5456篇 |
水产渔业 | 7512篇 |
畜牧兽医 | 74955篇 |
园艺 | 1736篇 |
植物保护 | 9476篇 |
出版年
2018年 | 2147篇 |
2017年 | 2401篇 |
2016年 | 2240篇 |
2015年 | 1896篇 |
2014年 | 2329篇 |
2013年 | 5572篇 |
2012年 | 4182篇 |
2011年 | 5012篇 |
2010年 | 3274篇 |
2009年 | 3303篇 |
2008年 | 4929篇 |
2007年 | 4601篇 |
2006年 | 4457篇 |
2005年 | 4084篇 |
2004年 | 4055篇 |
2003年 | 4054篇 |
2002年 | 3764篇 |
2001年 | 4595篇 |
2000年 | 4619篇 |
1999年 | 3629篇 |
1998年 | 1576篇 |
1997年 | 1501篇 |
1996年 | 1455篇 |
1995年 | 1670篇 |
1994年 | 1577篇 |
1993年 | 1467篇 |
1992年 | 3077篇 |
1991年 | 3191篇 |
1990年 | 3180篇 |
1989年 | 3101篇 |
1988年 | 2963篇 |
1987年 | 2922篇 |
1986年 | 2980篇 |
1985年 | 2892篇 |
1984年 | 2368篇 |
1983年 | 2084篇 |
1982年 | 1380篇 |
1979年 | 2154篇 |
1978年 | 1768篇 |
1977年 | 1563篇 |
1976年 | 1496篇 |
1975年 | 1567篇 |
1974年 | 1890篇 |
1973年 | 1974篇 |
1972年 | 1873篇 |
1971年 | 1745篇 |
1970年 | 1679篇 |
1969年 | 1592篇 |
1968年 | 1300篇 |
1967年 | 1411篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
D. Desmecht A. Linden H. Amory T. Art P. Lekeux 《Veterinary research communications》1996,20(4):371-379
Fifty-eight healthy horses were studied during five sporting events of various intensities and durations, namely show-jumping (n=6), cross-country in a three-day event (n=30), trotting races (n=7), galloping reces (n=7) and endurance rides (n=8). Venous blood samples were collected at rest and immediately after exercise and analysed for plasma cortisol (CORT) and lactate (LA) levels. The experimental procedure was the same throughout the investigation so as to permit a reliable comparison between the five types of exercise. The type of event significantly affected both the resting (p0.05) and the postexercise (p0.01) plasma CORT. The degree of exercise-induced hypercortisolaemia was related to both the intensity and the duration of exercise for all five sporting events, but the endurance ride induced the most and show-jumping the least serious post-exercise CORT changes. LA production was much more closely related to the intensity of the exercise than was CORT. It is concluded that simultaneous measurements of plasma CORT and LA levels may be useful to discriminate between different types of exercise, adjust training programmes, and improve our comprehension of the physiology of sport horses at exercise.Abbreviations CORT
cortisol
- E/R
exercise to rest ratio
- EDTA
ethylenediaminetetraacetic acid
- HR
heart rate
- LA
lactate 相似文献
992.
993.
994.
Clery D 《Science (New York, N.Y.)》1994,264(5163):1271-1273
995.
Clery D 《Science (New York, N.Y.)》1994,264(5163):1268-1270
996.
997.
998.
Amelinckx S Zhang XB Bernaerts D Zhang XF Ivanov V Nagy JB 《Science (New York, N.Y.)》1994,265(5172):635-639
The concept of a spatial-velocity hodograph is introduced to describe quantitatively the extrusion of a carbon tubule from a catalytic particle. The conditions under which a continuous tubular surface can be generated are discussed in terms of this hodograph, the shape of which determines the geometry of the initial nanotube. The model is consistent with all observed tubular shapes and explains why the formation process induces stresses that may lead to "spontaneous" plastic deformation of the tubule. This result is due to the violation of the continuity condition, that is, to the mismatch between the extrusion velocity by the catalytic particle, required to generate a continuous tubular surface, and the rate of carbon deposition. 相似文献
999.
Manipulation of the Avian Genome. Edited by R. J. Etches & A. M. V. Gibbins, 1993. 322 pp., illustrated in colour. Boca Raton, FL, CRG Press. ISBN 0–8493–4216–3.
Proceedings of the 8th European Symposium on Poultry Nutrition. Edited by The Organizing Committee, 1992. 373 pp. Milan, Italy. World's Poultry Science Association. 相似文献
1000.