全文获取类型
收费全文 | 112554篇 |
免费 | 6070篇 |
国内免费 | 66篇 |
专业分类
林业 | 5541篇 |
农学 | 3791篇 |
基础科学 | 657篇 |
13475篇 | |
综合类 | 20123篇 |
农作物 | 4270篇 |
水产渔业 | 5529篇 |
畜牧兽医 | 56673篇 |
园艺 | 1369篇 |
植物保护 | 7262篇 |
出版年
2018年 | 1592篇 |
2017年 | 1711篇 |
2016年 | 1594篇 |
2015年 | 1403篇 |
2014年 | 1718篇 |
2013年 | 4084篇 |
2012年 | 3204篇 |
2011年 | 3762篇 |
2010年 | 2546篇 |
2009年 | 2646篇 |
2008年 | 3867篇 |
2007年 | 3612篇 |
2006年 | 3515篇 |
2005年 | 3228篇 |
2004年 | 3264篇 |
2003年 | 3196篇 |
2002年 | 3033篇 |
2001年 | 3531篇 |
2000年 | 3529篇 |
1999年 | 2851篇 |
1998年 | 1257篇 |
1997年 | 1179篇 |
1996年 | 1153篇 |
1995年 | 1288篇 |
1994年 | 1227篇 |
1993年 | 1150篇 |
1992年 | 2262篇 |
1991年 | 2269篇 |
1990年 | 2353篇 |
1989年 | 2245篇 |
1988年 | 2155篇 |
1987年 | 2062篇 |
1986年 | 2102篇 |
1985年 | 2076篇 |
1984年 | 1725篇 |
1983年 | 1565篇 |
1982年 | 988篇 |
1979年 | 1548篇 |
1978年 | 1253篇 |
1977年 | 1108篇 |
1976年 | 1077篇 |
1975年 | 1154篇 |
1974年 | 1374篇 |
1973年 | 1350篇 |
1972年 | 1389篇 |
1971年 | 1350篇 |
1970年 | 1257篇 |
1969年 | 1266篇 |
1967年 | 1098篇 |
1966年 | 990篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Twenty-four red deer hinds with their calves were released on to a newly established pure red clover sward and, 2 days later, red staining of the tail, perineum and hocks was observed. This was presumed to be of urinary origin. Observation of micturition showed that when urine was passed, it was a normal straw colour but it turned scarlet-red about 1 hour after exposure to air. Midstream urine remained the normal colour when held under a pure nitrogen atmosphere immediately after micturition, but it turned red when held in air in the dark, suggesting that the colour change was due to an oxidative rather than a photosensitive reaction. All deer grazing red clover were affected but this did not occur in deer grazing ryegrass/white clover swards. No adverse effects were observed in the deer grazing the red clover, and calf growth was significantly higher than on ryegrass/white clover, suggesting that the red urine had no effect on health or productivity. Blood and urine analyses showed no signs of haemolysis, haematuria or haemoglobinuria. Preliminary chemical analyses suggest that the compounds involved are not those found in the urine of sheep grazing oestrogenic clover. The nature of the compounds have yet to be determined. 相似文献
992.
A. Das S. Katole M. Choubey S. P. Gupta M. Saini V. Kumar D. Swarup 《Journal of animal physiology and animal nutrition》2013,97(1):80-90
A feeding trial was conducted to know the level of concentrates in the diet of Antelope cervicapra at which diet digestibility and mineral utilization were optimum. Fifteen blackbucks (25–33 kg BW) were distributed into three groups of five each. Fresh oat (Avena sativa) and berseem (Trifolium alexandrinum) fodders were offered ad libitum to all the animals. In addition, animals in groups II and III received concentrate mixture at the rate of 0.5 and 1% of BW, whereas animals in group I received no concentrates. As the level of concentrates increased, consumption of fodder decreased resulting in decreased consumption of neutral detergent fibre (NDFom), acid detergent fibre (ADFom), hemicellulose and cellulose. However, overall total dry matter (DM) and organic matter (OM) intake was not significantly different between the groups. Digestibility of DM, OM and gross energy (GE) increased while that of NDFom and ADFom decreased with increased level of concentrates in the diet. Intake of P, Zn, Cu and Mn increased with increased level of concentrate supplementation; however, consumption of Ca and Fe followed the reverse trend. Absorption of P and Zn increased with increased level of concentrate supplementation. Serum concentration of Zn increased when concentrate was supplemented at the rate of 0.5% BW beyond which there was no further improvement. Increasing the level of concentrates in the diet was resulted in increased serum glucose and cholesterol levels. Forage‐only diet was inadequate in supply of energy, P and zinc. Supplementation of concentrates at the rate of 0.5% BW was able to meet the requirement of these nutrients. Supplementation at the rate of 1% BW supplied energy and P in excess of requirement. It was concluded that the feeding of concentrates to the captive blackbuck fed forage‐based diets should be restricted to 0.5% of BW. 相似文献
993.
994.
This report describes the successful management of a pregnant 14‐year‐old seven‐eighths Thoroughbred mare with an ovarian granulosa cell tumour. The mare initially presented with unilateral ovarian enlargement whilst being managed for artificial insemination, demonstrating normal ovarian function with ovulation from the contralateral ovary leading to conception. The mare subsequently re‐presented with stallion‐like behaviour at 3.5 months gestation and ovarian suppression was evident. The mare maintained her pregnancy and delivered a live colt foal at term. Ovariectomy was performed 3 months post foaling and the mare regained cyclic activity 9 months post surgery. The mare then conceived and became pregnant once more. The diagnostic and therapeutic challenges during pregnancy are discussed. 相似文献
995.
996.
Lipomatosis is an uncommon cause of colic. This case report details the pre‐ and intraoperative findings of a 9‐year‐old gelding, presented with acute abdominal pain. Exploratory laparotomy revealed a massive fatty infiltrate involving an extensive portion of the base and mid‐body of the caecum. To the authors' knowledge, this is the first report of an infiltrative lipomatous lesion of the equine caecum. 相似文献
997.
998.
999.
1000.
Our objective was to assess the association of managerial practices, general hygiene and Salmonella infection in Senegalese broiler flocks. Seventy broilers farms were studied from January 2000 to December 2001 around Dakar. A questionnaire was submitted to the farmers and samples of fresh broiler droppings were taken. A 28.6% of the flocks were infected by Salmonella (mainly Hadar and Brancaster serovars). Salmonella infection of the previous flock (OR=6.82) and of day-old chicks (OR=3.73), frequent poultry farmers’ visits (OR=5.38) and keeping sick birds inside the farm (OR=5.32) increased the risk of Salmonella infection. But, using antibiotics on day-old chicks (OR=0.17) and a detergent for cleaning (OR=0.16) decreased the risk. 相似文献