全文获取类型
收费全文 | 853篇 |
免费 | 52篇 |
国内免费 | 1篇 |
专业分类
林业 | 140篇 |
农学 | 64篇 |
基础科学 | 4篇 |
79篇 | |
综合类 | 111篇 |
农作物 | 17篇 |
水产渔业 | 32篇 |
畜牧兽医 | 419篇 |
园艺 | 14篇 |
植物保护 | 26篇 |
出版年
2021年 | 9篇 |
2020年 | 6篇 |
2019年 | 11篇 |
2018年 | 16篇 |
2017年 | 20篇 |
2016年 | 17篇 |
2015年 | 21篇 |
2014年 | 20篇 |
2013年 | 30篇 |
2012年 | 37篇 |
2011年 | 33篇 |
2010年 | 15篇 |
2009年 | 28篇 |
2008年 | 34篇 |
2007年 | 29篇 |
2006年 | 25篇 |
2005年 | 25篇 |
2004年 | 19篇 |
2003年 | 30篇 |
2002年 | 24篇 |
2001年 | 27篇 |
2000年 | 27篇 |
1999年 | 14篇 |
1998年 | 12篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1994年 | 9篇 |
1992年 | 14篇 |
1991年 | 14篇 |
1990年 | 12篇 |
1989年 | 22篇 |
1988年 | 19篇 |
1987年 | 11篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1977年 | 14篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 6篇 |
1972年 | 9篇 |
1971年 | 8篇 |
1969年 | 8篇 |
1967年 | 8篇 |
1966年 | 14篇 |
1924年 | 5篇 |
1921年 | 9篇 |
排序方式: 共有906条查询结果,搜索用时 0 毫秒
901.
902.
1000 random serum samples of pet dogs were examined in the serum tube agglutination test for antibodies to Brucella canis. Agglutinating antibodies to Br. canis antigen were detected in 18 cases in a serum dilution of 1 : 50, in 29 cases in a serum dilution of 1 : 100, in 13 cases in a serum dilution of 1 : 200 and in a serum dilution 1 : 400. But the positive results of the agglutination tests were confirmed by complement fixation, agargel-precipitation and indirect immunofluorescence only in 2 cases (0,2%) with titers of 1 :200 and 1 :400. These serological findings indicate that in the Federal Republic of Germany Br. canis infections are rarely in pet dogs as compared with dogs (Beagles) held in research kennels. 相似文献
903.
R Kasimanickam M Asay S Schroeder V Kasimanickam JM Gay JP Kastelic JB Hall WD Whittier 《Reproduction in domestic animals》2014,49(6):1063-1067
Profitability of a beef operation is determined by the proportion of cows attaining pregnancy early in the breeding season and those that are pregnant at the end of breeding season. Many factors, including temperament, contribute to those reproductive parameters. The objective of this study was to evaluate effects of temperament on reproductive performance of beef cows. In Experiment 1, Angus and Angus‐cross beef cows (n = 1546) from eight locations were assigned a body condition score (BCS; 1 = emaciated; 9 = obese) and chute exit and gait score (1 = slow exit, walk; calm temperament; 2 = jump, trot or run; excitable temperament). Cows were grouped with bulls (1 : 25 to 1 : 30; with satisfactory breeding potential and free of venereal disease) for an 85‐day breeding season. Pregnancy status and stage of gestation were determined (transrectal palpation) 35 days after the end of the breeding season. Controlling for BCS (p < 0.01) and handling facility (p < 0.0001) and handling facility by temperament score interaction (p < 0.001), breeding season pregnancy rate was lower in excited versus calm cows [88.6% (798/901) vs 94.1% (607/645); p < 0.001]. Cows with an excitable temperament took 24 more days to become pregnant compared to calm cows (median days to pregnancy, 35 vs 59 days; p < 0.0001). In Experiment 2, Angus and Angus‐cross beef cows (n = 1407) from 8 locations were assigned scores for body condition and chute exit and gait (as described in Experiment 1) and assigned to bulls (breeding sound and free of venereal disease; 1 : 25 to 1 : 30) for 85 days. Pregnancy status was determined by transrectal palpation at 2 and 6 months after the onset of the breeding season. Controlling for BCS (p < 0.05), pregnancy loss was higher in excited versus calm cows [5.5% (36/651) vs 3.2% (20/623), p < 0.0001]. In conclusion, beef cows with an excitable temperament had significantly lower reproductive performance than calmer cows. The modified two‐point chute exit–gait scoring method was repeatable and identified cattle with an excitable temperament. 相似文献
904.
Journal of Plant Diseases and Protection - In a survey of Botrytis populations in Northern Germany in 2012-2014, an average of 67.7% and 73.8% of isolates from strawberry and raspberry fields... 相似文献
905.
Pampusch MS White ME Hathaway MR Baxa TJ Chung KY Parr SL Johnson BJ Weber WJ Dayton WR 《Journal of animal science》2008,86(12):3418-3423
906.
Weber ER Helps CR Foster AP Perry AC Gruffydd-Jones TJ Hall L Harbour DA Duffus WP 《Veterinary immunology and immunopathology》2000,76(3-4):299-308
A feline splenic cDNA library was screened with a (32)P-labelled cDNA probe encoding the canine IgE epsilon heavy chain subunit. A cDNA sequence of 1614 nucleotides encoding the complete feline IgE heavy chain, as well as a portion of a variable region, was identified. A search of the GenBank database revealed an identity of 82% at the nucleotide level and 76% at the amino acid level between the feline epsilon heavy chain sequence and the canine homologue. In a separate study, feline genomic DNA, isolated from whole feline embryo cells, was subjected to PCR amplification using primers based on known partial genomic DNA sequences for the feline C epsilon gene. Following removal of an intron from the 683 bp PCR product, the coding sequence yielded an ORF of 506 bp. The DNA sequence of this PCR clone differed by a single nucleotide from the cDNA clone. This difference is silent, and therefore the proteins encoded by the two sequences are identical over the regions cloned and sequenced. Phylogenetic analysis of the constant regions of nine immunoglobulin epsilon genes revealed that the feline cDNA is most similar to the canine homologue. 相似文献