全文获取类型
收费全文 | 30302篇 |
免费 | 1298篇 |
国内免费 | 8篇 |
专业分类
林业 | 1072篇 |
农学 | 893篇 |
基础科学 | 174篇 |
4569篇 | |
综合类 | 3980篇 |
农作物 | 1167篇 |
水产渔业 | 1146篇 |
畜牧兽医 | 16492篇 |
园艺 | 336篇 |
植物保护 | 1779篇 |
出版年
2021年 | 224篇 |
2020年 | 265篇 |
2019年 | 332篇 |
2018年 | 602篇 |
2017年 | 665篇 |
2016年 | 566篇 |
2015年 | 364篇 |
2014年 | 552篇 |
2013年 | 1665篇 |
2012年 | 865篇 |
2011年 | 1117篇 |
2010年 | 809篇 |
2009年 | 762篇 |
2008年 | 1080篇 |
2007年 | 1055篇 |
2006年 | 891篇 |
2005年 | 713篇 |
2004年 | 722篇 |
2003年 | 662篇 |
2002年 | 584篇 |
2001年 | 744篇 |
2000年 | 743篇 |
1999年 | 544篇 |
1998年 | 244篇 |
1997年 | 227篇 |
1995年 | 269篇 |
1992年 | 400篇 |
1991年 | 416篇 |
1990年 | 432篇 |
1989年 | 441篇 |
1988年 | 344篇 |
1987年 | 353篇 |
1986年 | 383篇 |
1985年 | 342篇 |
1984年 | 331篇 |
1983年 | 303篇 |
1979年 | 481篇 |
1978年 | 328篇 |
1977年 | 370篇 |
1976年 | 468篇 |
1975年 | 485篇 |
1974年 | 523篇 |
1973年 | 480篇 |
1972年 | 438篇 |
1971年 | 354篇 |
1970年 | 373篇 |
1969年 | 434篇 |
1968年 | 441篇 |
1967年 | 446篇 |
1966年 | 438篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Trent AM Bailey JV 《The Canadian veterinary journal. La revue veterinaire canadienne》1985,26(1):16-19
A three year old Charolais bull was examined because of anorexia and depression of five days duration and progressive abdominal distention. Intestinal obstruction was diagnosed. A right flank celiotomy allowed diagnosis and correction of a herniated jejunoileal loop through the right lateral ligament of the bladder. An annular constriction located in mid-ileum was by-passed by ileocecal side-to-side anastomosis. The bull's appetite and fecal production returned to normal within 72 hours of surgery. Ten months following discharge the bull was reported to be well. 相似文献
92.
93.
The lungs of 334 pigs were obtained from two slaughter plants in Minnesota and examined in detail. Macroscopic and microscopic evaluation, direct fluorescence for Mycoplasma hyopneumoniae and bacterial culture were done on all of them and a subsample of 50 were selected for virus culture. Mycoplasma hyopneumoniae, Pasteurella multocida and Haemophilus spp. were detected in 24.0%, 34.1% and 27.0% of the lungs, commonly in conjunction with each other. One isolate of Haemophilus pleuropneumoniae serotype 2 was detected and this represents the first report of its presence in the United States. No virus was detected in any of the lungs. Lungs with both M. hyopneumoniae and Pasteurella multocida had the greatest amount of macroscopic pneumonia (9.8% of the lung). Lungs with M. hyopneumoniae or P. multocida alone had 4.9% and 5.2% of the lung involved with pneumonia respectively. Lungs with Haemophilus sp. Taxon "minor group" had 3.8% of the lung involved which was not significantly different from lungs with none of these organisms being detected (1.6%). There was a positive correlation between the extent of M. hyopneumoniae infection, as scored by FAT and the amount of macroscopic pneumonia present (r = 0.46; P less than 0.001). Likewise, there was a positive correlation between the estimated concentration of P. multocida present, as scored by the relative number of colonies on blood agar and the amount of macroscopic pneumonia present (r = 0.60; P less than 0.001). Microscopically, the amount of lymphoreticular proliferation, polymorphonuclear cells and alveolar macrophages were evaluated.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
94.
95.
96.
97.
Hirsch VM McLaughlin BG Parent J 《The Canadian veterinary journal. La revue veterinaire canadienne》1983,24(10):301-304
Lymphosarcoma in a six year old male Doberman pinscher was accompanied by hypercalcemia, generalized osteolysis and renal calcification. Tumor involvement of bone marrow was extensive. The possible pathogenesis of hypercalcemia was thought to be the result of a locally active bone-resorbing factor secreted by the tumor cells. 相似文献
98.
99.
1. The effect of feeding the detergent, sodium lauryl sulphate at concentrations up to 10 g/kg diet on egg‐shell quality was examined in laying hens at 24, 36 and 48 weeks of age.
2. Lauryl sulphate at 2.5 g/kg or more in the diet significantly increased shell breaking strength, shell thickness and shell weight at 24 and 36 weeks. In 48‐week‐old hens only shell breaking strength was increased significantly. Egg production and egg weight were not affected significantly by lauryl sulphate.
3. Lauryl sulphate might increase these measures of quality by increasing shell deposition and/or shell elasticity. 相似文献
100.