全文获取类型
收费全文 | 172521篇 |
免费 | 9413篇 |
国内免费 | 1971篇 |
专业分类
林业 | 7884篇 |
农学 | 6795篇 |
基础科学 | 2053篇 |
22263篇 | |
综合类 | 31614篇 |
农作物 | 7442篇 |
水产渔业 | 8632篇 |
畜牧兽医 | 82679篇 |
园艺 | 3029篇 |
植物保护 | 11514篇 |
出版年
2021年 | 1777篇 |
2020年 | 1950篇 |
2019年 | 2156篇 |
2018年 | 2814篇 |
2017年 | 3386篇 |
2016年 | 3003篇 |
2015年 | 2743篇 |
2014年 | 3429篇 |
2013年 | 7381篇 |
2012年 | 6047篇 |
2011年 | 7158篇 |
2010年 | 5068篇 |
2009年 | 5095篇 |
2008年 | 6935篇 |
2007年 | 6530篇 |
2006年 | 5992篇 |
2005年 | 5515篇 |
2004年 | 4987篇 |
2003年 | 5035篇 |
2002年 | 4705篇 |
2001年 | 5427篇 |
2000年 | 5325篇 |
1999年 | 4161篇 |
1998年 | 1831篇 |
1997年 | 1756篇 |
1996年 | 1572篇 |
1995年 | 1827篇 |
1994年 | 1637篇 |
1993年 | 1474篇 |
1992年 | 3051篇 |
1991年 | 3280篇 |
1990年 | 3065篇 |
1989年 | 3151篇 |
1988年 | 2837篇 |
1987年 | 2780篇 |
1986年 | 2891篇 |
1985年 | 2735篇 |
1984年 | 2205篇 |
1983年 | 1970篇 |
1979年 | 2137篇 |
1978年 | 1731篇 |
1977年 | 1414篇 |
1976年 | 1465篇 |
1975年 | 1556篇 |
1974年 | 1832篇 |
1973年 | 1855篇 |
1972年 | 1752篇 |
1971年 | 1552篇 |
1970年 | 1523篇 |
1969年 | 1573篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
91.
92.
Individual antigens of goats 总被引:1,自引:0,他引:1
93.
T M Frye S N Williams T W Graham 《Veterinary Clinics of North America: Food Animal Practice》1991,7(1):217-275
Deficiencies of vitamins A, D, K, E and thiamin can cause severe limitations in beef production. In particular, vitamin A and E can be common causes of lost profit, secondary to limitations of reproductive and growth potential. Prolonged dry periods will reduce available A and E in pasture forage, as can ensiling and prolonged storage of harvested feedstuffs. Polioencephalomalacia is a thiamin responsive disorder, associated with high concentrate feeding and lush pastures. Antimetabolites, such as amprolium, will cause thiamine deficiency when fed in excess. Recent information has shown improved performance with supplemental beta carotene and niacin. The positive responses in reproductive performance, noted with cattle fed supplemental beta carotene, was independent of vitamin A. Supplementation of vitamins above National Research Council recommendations can be justified. However, proper evaluation of feed and animal status, and documentation of a response to supplementation is necessary before diagnosing deficiencies of specific nutrients. 相似文献
94.
N Saito H Yamanaka S Nagasawa 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1991,53(1):1-4
The activity of rat liver glutathione-insulin transhydrogenase (GIT) was measured by HPLC. The degradation of fluorescein isothiocyanate-I (FITC-I)-labeled insulin is separated into several peaks, which are bound different amount of FITC-I. We selected mono-fluorescein-thiocarbamylated insulin to estimate the decrease of insulin content and it became possible to assay GIT activity. This novel method was time-saving and simple, and this system could utilize instead of previous method. 相似文献
95.
96.
L A Janssens 《Veterinary surgery : VS》1991,20(4):274-278
Seven foci of pain (trigger points) were identified in the triceps brachii, infraspinatus, adductor-pectineus, peroneus longus, gluteus medius, ileocostorum lumborum, and quadriceps femoris muscles in 48 lame dogs. The dogs had been lame for 1 day to 150 weeks (mean, 24 weeks). Thirty-one dogs had been treated unsuccessfully with corticosteroids, nonsteroidal anti-inflammatory drugs, analgesics, or acupuncture. Palpating the trigger points induced severe pain. Treatment consisted of weekly stimulation of the trigger points by needling or injection of a local anesthetic. The mean treatment period was 2.8 weeks. Excellent results and complete recovery were observed in 34 dogs (60%). 相似文献
97.
98.
AM Mwanza A Madej H Kindahl N Lundeheim & S Einarsson 《Reproduction in domestic animals》2001,36(3-4):157-161
The effects of lipopolysaccharide ( Escherichia coli , O55:B5), administered 18 h after ovulation in the second oestrus after weaning on the hormonal profiles in 14 Swedish cross-bred (Landrace × Yorkshire) multiparous sows were studied. The endotoxin group (E-group) sows were administered with 300 ng/kg of lipopolysaccharide (LPS) whereas the control group (C-group) sows were administered 5 ml of saline intravenously via an indwelling jugular cannula. Blood samples for hormonal analyses were collected from all sows until slaughter. In the E-group, progesterone, cortisol and prostaglandin F2α metabolite levels increased significantly (p < 0.05) following LPS compared with the C-group. It can be concluded from this study that apart from elevating cortisol and prostaglandin F2α metabolite, LPS also elevates progesterone levels. 相似文献
99.
100.
C. P. Verschueren P. J. Selman J. J. M. de Vijlder J. A. Mol 《Domestic animal endocrinology》1991,8(4):509-519
Canine thyroglobulin (cTg) has been isolated and purified. It has similar electrophoretic patterns as Tg from other mammalian species. The main fraction had a MW of 660,000, whereas also fractions of a MW of approximately 1,300,000 (dimer) and 330,000 (subunit) were present. The iodine content was 0.8 to 1.0 % (w/w). cTg did not cross-react with antibodies against human Tg to a degree that would allow the use of a radioimmunoassay for human Tg for the determination of cTg in serum or plasma. Therefore a polyclonal antiserum was raised against cTg and a homologous radioimmunoassay was developed, which was sensitive (0.4 μg/l) and specific (cross-reactivity in cTg assay of human Tg, goat Tg, T4, T3, and DIT < 0.01 %).
Plasma Tg levels in normal dogs of both sexes and aged 3–15 years amounted to 192 ± 73 μg/l (mean ± SD, n=30). There was no relation between plasma Tg and T4 levels. 相似文献