全文获取类型
收费全文 | 84028篇 |
免费 | 3000篇 |
国内免费 | 45篇 |
专业分类
林业 | 6551篇 |
农学 | 3161篇 |
基础科学 | 610篇 |
10563篇 | |
综合类 | 16558篇 |
农作物 | 4769篇 |
水产渔业 | 4427篇 |
畜牧兽医 | 33039篇 |
园艺 | 1752篇 |
植物保护 | 5643篇 |
出版年
2018年 | 3672篇 |
2017年 | 3714篇 |
2016年 | 1898篇 |
2015年 | 584篇 |
2014年 | 608篇 |
2013年 | 1939篇 |
2012年 | 2210篇 |
2011年 | 4103篇 |
2010年 | 3590篇 |
2009年 | 2759篇 |
2008年 | 3227篇 |
2007年 | 3675篇 |
2006年 | 1470篇 |
2005年 | 1566篇 |
2004年 | 1492篇 |
2003年 | 1645篇 |
2002年 | 1482篇 |
2001年 | 1514篇 |
2000年 | 1541篇 |
1999年 | 1215篇 |
1995年 | 607篇 |
1994年 | 581篇 |
1993年 | 585篇 |
1992年 | 1352篇 |
1991年 | 1402篇 |
1990年 | 1457篇 |
1989年 | 1509篇 |
1988年 | 1424篇 |
1987年 | 1358篇 |
1986年 | 1403篇 |
1985年 | 1376篇 |
1984年 | 1153篇 |
1983年 | 1009篇 |
1982年 | 722篇 |
1981年 | 689篇 |
1980年 | 645篇 |
1979年 | 1128篇 |
1978年 | 916篇 |
1977年 | 836篇 |
1976年 | 770篇 |
1975年 | 863篇 |
1974年 | 1129篇 |
1973年 | 1066篇 |
1972年 | 1132篇 |
1971年 | 1082篇 |
1970年 | 1023篇 |
1969年 | 878篇 |
1968年 | 730篇 |
1967年 | 851篇 |
1966年 | 693篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
211.
In this paper, a case of otitis media with effusion (‘glue ear’) is described in a Cavalier King Charles spaniel. Its presentation, diagnosis and surgical management by the insertion of a trans-tympanic ventilation tube (grommet) is discussed. 相似文献
212.
213.
214.
Alteration of nitrogen metabolism by alpha-ketoglutarate administration in growing lambs fed high nonprotein nitrogen-containing diets 总被引:1,自引:0,他引:1
Two completely randomized design experiments were conducted, using either 10, 38-kg (Exp. 1) or 10, 26-kg (Exp. 2) Hampshire x Western wether lambs, to study the effects of alpha-ketoglutarate (AKG) administration on N metabolism. Lambs were fed 890 and 885 g DM/d in Exp. 1 and 2, respectively, of corn-cottonseed hull basal diets with urea added to attain CP levels of 10.6 and 10.5% in Exp. 1 and 2, respectively. Experiments consisted of 10 d of adaptation followed by 7 d of infusion and excreta collection. Lambs were infused continuously either i.v. (Exp. 1) or abomasally (Exp. 2) with control solutions (CON) or solutions containing 41.3 g AKG/d (AKG). In Exp. 1, fecal and urinary N excretion and N retention were not affected (P greater than .10) by treatment. Compared to CON in Exp. 2, AKG infusion increased (P less than .10) fecal N output (6.6 vs 5.9 g N/d) but did not affect (P greater than .10) the amount of N retained (4.4 vs 3.5 g N/d). Compared to CON, AKG increased (P less than .10) urinary NH3 N excretion in Exp. 1. Serum urea N was lower (P greater than .10) for AKG than for CON in Exp. 1 but was not affected (P greater than .10) by treatment in Exp. 2. In Exp. 1, AKG appeared to reduce activities of several serum enzymes that function in amino N metabolism. In Exp. 1, compared to CON, AKG decreased (P less than .10) aspartate but increased (P less than .10) asparagine in serum.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
215.
G. C. W. England W. Edward Allen D. J. Porter 《The Journal of small animal practice》1989,30(8):441-443
A two-year-old dog was presented with no scrotal testes. There was no history of castration but at laparotomy no testes were found. To confirm that the dog was truly anorchid a human chorionic gonadotrophin stimulation test was performed. This was then validated in normal entire and castrated dogs. 相似文献
216.
217.
Scripture EW 《Science (New York, N.Y.)》1899,9(234):878-880
218.
219.
Castle WA 《Science (New York, N.Y.)》1938,87(2267):531-534
220.
Davis WM 《Science (New York, N.Y.)》1884,3(69):654-657