全文获取类型
收费全文 | 207篇 |
免费 | 23篇 |
专业分类
林业 | 11篇 |
农学 | 5篇 |
14篇 | |
综合类 | 10篇 |
农作物 | 3篇 |
水产渔业 | 21篇 |
畜牧兽医 | 157篇 |
园艺 | 3篇 |
植物保护 | 6篇 |
出版年
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 2篇 |
2012年 | 6篇 |
2011年 | 3篇 |
2010年 | 5篇 |
2009年 | 7篇 |
2008年 | 8篇 |
2007年 | 3篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 6篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 11篇 |
1974年 | 12篇 |
1973年 | 6篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1968年 | 1篇 |
1967年 | 5篇 |
1966年 | 1篇 |
1910年 | 2篇 |
排序方式: 共有230条查询结果,搜索用时 46 毫秒
71.
72.
73.
Y. M. Abouzeed H. Hariharan C. Poppe F. S. B. Kibenge 《Comparative immunology, microbiology and infectious diseases》2000,23(4)
Non-typhoid Salmonella serovars remain a potential threat to human health, and beef cattle and broiler chickens are possible sources of these organisms on Prince Edward Island (PEI). In this study, the ceca of beef cattle belonging to fasted and non-fasted groups, and broiler chickens were examined for Salmonella at the time of slaughter. The characteristics of the isolates, including antimicrobial resistance patterns and virulence genes, were studied along with the isolates obtained from cases of human salmonellosis on PEI during the study period (1996–97). The prevalence of Salmonella in beef cattle was 4.6% (11/240). The rate was significantly higher in fasted cattle (7.46%), than in non-fasted cattle (0.94%). The prevalence rate in chickens was 32.5% (39/120). In beef cattle, Salmonella typhimurium phage type (PT) or definitive type (DT) 104 which was resistant to ampicillin, chloramphenicol, streptomycin, sulfisoxazole and tetracycline, was the most predominant type (64%). In chickens, S. heidelberg, with resistance to gentamicin, streptomycin and sulfisoxazole, predominated. Of 26 isolates from humans, the most common serovar was S. typhimurium, including a multidrug-resistant strain of DT104. Examination by PCR revealed presence of the virulence gene invA in all serovars, and the spvC gene in all S. typhimurium isolates, of both beef cattle and human origin. Among the other serovars the latter gene was found in 7 human isolates, but in none of the chicken or beef isolates. All but 3 of the spvC-positive isolates possessed a 90 kilobasepair (kbp) plasmid suggesting that the 3 isolates had the spvC gene on their chromosome. These findings were confirmed by plasmid DNA isolation using 3 different protocols and by sequence analysis of the spvC-PCR product. 相似文献
74.
Long-distance free-space distribution of quantum entanglement 总被引:1,自引:0,他引:1
Aspelmeyer M Böhm HR Gyatso T Jennewein T Kaltenbaek R Lindenthal M Molina-Terriza G Poppe A Resch K Taraba M Ursin R Walther P Zeilinger A 《Science (New York, N.Y.)》2003,301(5633):621-623
We demonstrate the distribution of quantum entanglement via optical free-space links to independent receivers separated by 600 m, with no line of sight between each other. A Bell inequality between those receivers is violated by more than four standard deviations, confirming the quality of the entanglement. This outdoor experiment represents a step toward satellite-based distributed quantum entanglement. 相似文献
75.
76.
Shrinkage factors applied to the additive main effects and multiplicative interaction (AMMI) models improve prediction of
cultivar responses in multi-environment trials (MET). Estimates of shrinkage factors based on the eigenvalue partition (EVP)
method may get a further improvement in the predictions of cell means. Objectives of this work were: (1) to compare the EVP-based
shrinkage method with unshrunken AMMI, best linear unbiased predictor (BLUP) and other shrunken method (herein named CCC),
when they were applied to five maize MET and simulation data; (2) to assess by cross validation the equation which estimates
the standard error of predicted means (SEPM) based on the EVP theory; (3) to estimate the genotype × environment interaction
(GEI) variance components after applying the EVP shrinkage method to the five maize MET. Empirical data of five maize MET
and simulation data were used for cross validation of the methods using the root mean square predictive difference (RMSPD)
criterion. The RMSPD of the shrunken EVP predicted cell means was generally smaller than those of the other methods, suggesting
that the EVP method was generally better predictor than the other methods. The truncated AMMI was the worst among the four
methods studied. The EVP-based equation, which predicts the SEPM, was a good predictor as determined by the RMSPD cross validation
criterion, with the advantage that it does not need one replication for validation. Estimates of mean squares, and GEI and
error variances associated with the GEI effects were smaller for the shrunken EVP predicted effects than for the original
data.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
77.
A dynamic, partially stochastic mathematical model describing the reproductive performance of a sow herd is presented. The model stimulates a herd that averages 17.27 sow days/pig produced, with a mean of 9.06 pigs weaned/litter and 2.327 litters produced/sow each year. Several alternative options are simulated. Of these, the ones that increase the litter size at weaning appear most beneficial in terms of both biological and economic efficiencies. 相似文献
78.
A national survey to estimate the prevalence of Salmonella species among Canadian registered commercial turkey flocks.
下载免费PDF全文
![点击此处可从《Canadian journal of veterinary research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
R J Irwin C Poppe S Messier G G Finley J Oggel 《Canadian journal of veterinary research》1994,58(4):263-267
In 1990-1991, a national survey was conducted to estimate the prevalence of Salmonella species among Canadian commercial turkey flocks. Two hundred and seventy flocks were randomly selected across Canada. The proportion sampled from each province was selected according to each province's share of the national turkey market. Samples, consisting of 12 pooled litter and four pooled dust samples, were used to determine the Salmonella status of the environment of each flock. Additionally, a one kilogram sample of feed was taken from each flock premise. Salmonella was recovered from environmental samples in 234/270 (86.7%) of flocks and from feed samples in 26/266 (9.8%) of flocks. Forty-eight different Salmonella serovars were isolated from flock environmental samples. The most prevalent serovars were S. anatum, S. hadar, S. agona, S. heidelberg and S. saintpaul which were isolated from 53/270 (19.6%), 49/270 (18.1%), 49/270 (18.1%), 42/270 (15.6%) and 34/270 (12.6%) flocks, respectively. 相似文献
79.
Oral administration of ascorbic acid to horses 总被引:1,自引:0,他引:1
The effects of oral administration of high doses of ascorbic acid on plasma concentrations were investigated in both experimental Thoroughbred horses and those within racing stables. A single oral dose (20 g) did not result in any increase in plasma concentrations. However, daily administration of either 4.5 g or 20 g doses resulted in significant increases in plasma concentrations. Monthly variations in plasma ascorbate concentrations were found in both supplemented (20 g daily) and unsupplemented stables. It is concluded that oral supplementation with ascorbic acid is a satisfactory route to increase plasma and tissue concentrations. 相似文献
80.
Indocyanine green clearance and ammonia tolerance in partially hepatectomized and hepatic devascularized, anesthetized dogs 总被引:2,自引:0,他引:2
K W Prasse D E Bjorling R A Holmes L M Cornelius 《American journal of veterinary research》1983,44(12):2320-2323
Indocyanine green clearance and ammonia tolerance were measured in anesthetized dogs with 60% hepatectomy, 40% hepatectomy, portacaval shunt, and hepatic artery ligation. With a dose of 0.5 mg of indocyanine green/kg of body weight, plasma clearance of the dye was significantly (P less than 0.001) delayed only in dogs with 60% hepatectomy. Ammonia tolerance was abnormal in dogs in this group, because after they were given a gastric challenge load of an ammonium salt, they had a 5-fold increase in plasma ammonia concentration, compared with a 2.5-fold increase in the control group. Before challenge loading, base-line plasma ammonia concentration was significantly (P less than 0.05) increased within 5 minutes after surgical preparation of the portacaval shunt. After challenge loading the stomach with an ammonium salt, dogs with portacaval shunt had increased plasma ammonia concentration, but the amount was not significantly different from postchallenge-loading values in control dogs. Dogs with 40% hepatectomy and with hepatic artery ligation could not be differentiated from control dogs by indocyanine green clearance or by ammonia tolerance testing. Abnormal tolerance to a challenge gastric load of an ammonium salt or delayed clearance of indocyanine green may indicate marked loss of functional hepatic mass, but normal tolerance or normal dye clearance may not exclude liver disease or dysfunction. Seemingly, base-line plasma ammonia concentration was a sensitive indicator of abnormal portal circulation.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献