首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   125篇
  免费   11篇
  国内免费   2篇
林业   12篇
农学   8篇
基础科学   1篇
  13篇
综合类   7篇
农作物   4篇
水产渔业   7篇
畜牧兽医   81篇
园艺   4篇
植物保护   1篇
  2022年   2篇
  2021年   1篇
  2020年   3篇
  2018年   2篇
  2017年   5篇
  2016年   7篇
  2015年   6篇
  2014年   3篇
  2013年   11篇
  2012年   9篇
  2011年   7篇
  2010年   4篇
  2009年   3篇
  2008年   10篇
  2007年   5篇
  2006年   12篇
  2005年   7篇
  2004年   15篇
  2003年   9篇
  2002年   10篇
  2001年   4篇
  1998年   1篇
  1997年   1篇
  1974年   1篇
排序方式: 共有138条查询结果,搜索用时 31 毫秒
51.
Two taurine breeds, Japanese Black and Holstein, established from geographically distant origins and selected for different uses, beef and dairy, were extensively genotyped using a genome‐wide single nucleotide polymorphism (SNP) chip with more than 1000 animals of each breed. The genetic structure was examined by principal component analysis, in which the first principal component clearly separated the two breeds and explained more than 15% of the variance. Highly differentiated SNPs were detected throughout the genome, some of which were clustered within small regions on BTA4 (79.2–79.7 Mb, Btau4.0) and BTA26 (22.2–23.6 Mb). A breed assignment test was developed using 18 highly differentiated SNPs to distinguish Japanese Black from F1 (Japanese Black × Holstein) and Holstein. The error rate that an F1 or Holstein animal is misjudged as Japanese Black was expected to be < 0.8%, while the error rate that a Japanese Black animal is misjudged as F1 or Holstein was expected to be < 0.001%. This test provides a reliable and powerful method to detect breed label falsification in retail beef.  相似文献   
52.
The water chemistry of 51 headwater streams was studied in the Tanzawa Mountains, western fringe of Southern Kanto Plain, Japan. The relationships to soil N processes and catchment topography were also evaluated using a geographic information system with fine-scale map data. The average concentration of total dissolved N was 0.74 mg-N L−1, of which 95% consisted of NO3 -N. Stream N concentrations were not different among bedrock geologies and among vegetations of the catchments. Stream NO3 -N marginally correlated to soil nitrification. Stream NO3 -N also tended to be high in areas with steep and south-facing slopes. These results imply that N transport from Tanzawa forest ecosystems is related to hydrological and biological processes associated with catchment topography. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   
53.
More than 200,000 tons of scallop shells are disposed annually alone in Japan. Nanoparticles derived from scallop shells have the potential to adsorb gaseous formaldehyde; therefore, such discarded shells have now been tested as additive filler in plywood adhesive by mixing high specific surface area, urea-modified shell nanoparticles with a resorcinol–formaldehyde resin. With this procedure, it was found that the emission of formaldehyde from the resulting plywood could be substantially reduced. The urea-modified scallop shell nanoparticles were prepared by two different methods: (1) a dry method where the shells were treated by planetary ball-grinding under ambient conditions—a completely dried powder was obtained after addition of the surface-modifying urea solution; (2) a moist method by treating dry ground shell particles in a wet grinding process with the urea solution, followed by centrifugation to obtain a paste. The specific surface area of the nanoparticles obtained by both treatments was 42 ± 3 m2/g. Measurement of the subsequent formaldehyde emission showed that the addition of the modified scallop shell nanoparticles substantially reduced the formaldehyde emission from plywood. The reduction of the specific mass uptake of urea depends on the nanoparticles which especially was the case when resins containing nanoparticles processed by the moist method were used.  相似文献   
54.
Bitter gourd ( Momordica charantia L.) is a popular tropical vegetable in Asian countries. Previously it was shown that bitter gourd placenta extract suppressed lipopolysaccharide (LPS)-induced TNFalpha production in RAW 264.7 macrophage-like cells. Here it is shown that the butanol-soluble fraction of bitter gourd placenta extract strongly suppresses LPS-induced TNFalpha production in RAW 264.7 cells. Gene expression analysis using a fibrous DNA microarray showed that the bitter gourd butanol fraction suppressed expression of various LPS-induced inflammatory genes, such as those for TNF, IL1alpha, IL1beta, G1p2, and Ccl5. The butanol fraction significantly suppressed NFkappaB DNA binding activity and phosphorylation of p38, JNK, and ERK MAPKs. Components in the active fraction from bitter gourd were identified as 1-alpha-linolenoyl-lysophosphatidylcholine (LPC), 2-alpha-linolenoyl-LPC, 1-lynoleoyl-LPC, and 2-linoleoyl-LPC. Purified 1-alpha-linolenoyl-LPC and 1-linoleoyl-LPC suppressed the LPS-induced TNFalpha production of RAW 264.7 cells at a concentration of 10 microg/mL.  相似文献   
55.
Suppressive effects of neocarrabiose 4-O-sulfate on the thermal and freeze denaturation of myosin subfragment-1 (S-1) and on myofibrils were investigated. The compound strongly suppressed the thermal denaturation of S-1. Its suppressive effect was greater than that of sorbitol and similar to that of maltose. However, it tended to accelerate the denaturation of myofibrils, suggesting a loss of protection by F-actin upon its addition. The compound suppressed the freeze denaturation of myofibrils and S-1. The effect was similar to that of sorbitol or maltose, and completely different from that of Na-sulfate. The compound solubilized myofibrils at concentrations similar to KCl. Therefore, it was concluded that neocarrabiose 4-O-sulfate behaved as an ionic salt in the thermal treatment process, whereas it behaved as a sugar in the frozen storage process.  相似文献   
56.
OBJECTIVE: Adequate fruit and vegetable intake has been suggested to protect against colorectal cancer. However, several recent prospective studies have reported no association. We therefore examined the association between fruit and vegetable intakes and the risk of colorectal cancer in a prospective cohort study in Japan. DESIGN: Between June and August 1990, 47 605 Japanese men and women completed a self-administered questionnaire, including a food-frequency questionnaire. We divided the subjects into quartiles based on their self-reported fruit and vegetable consumption. There were 165 colon cancer and 110 rectal cancer incidences identified during 7 years of follow-up, to the end of December 1997. We used Cox proportional hazards models to estimate the relative risk (RR) of developing colorectal cancer according to the level of fruit and vegetable consumption, applying adjustments for potential confounders. RESULTS: No statistically significant association was observed between fruit and vegetable consumption and the risk of colorectal cancer. The multivariate RR of colon cancer in the highest quartile of fruit and vegetable intake compared with the lowest was 1.13 (95% confidence interval (CI) 0.73-1.75), the RR for vegetables alone was 1.24 (95% CI 0.79-1.95) and that for fruit alone was 1.45 (95% CI 0.85-2.47). The corresponding multivariate RRs for rectal cancer were 1.12 (95% CI 0.67-1.89), 1.14 (95% CI 0.67-1.93) and 1.41 (95% CI 0.73-2.73). CONCLUSIONS: We found no association between the consumption of fruit and vegetables and the risk of colorectal cancer among the Japanese population.  相似文献   
57.
拖拉机沿曲线路径的跟踪控制   总被引:6,自引:2,他引:6  
近年关于农业用车轮型移动机器人的研究很多,但主要集中在直线行走方面。该研究进行了沿给定的曲线路径跟踪控制的研究。首先由给定的曲线路径生成四元状态空间,其次在利用预见控制求得车辆的未来值和目标值的基础上,利用最优控制理论设计跟踪控制器。最后在牧草地上对正弦路径和圆形路径进行了跟踪实验。试验结果为:车辆以1.5 m/s的速度行驶时,在很小转弯半径时最大误差可控制在35 cm以内。  相似文献   
58.
Bordetella bronchiseptica (B. bronchiseptica) is associated with respiratory tract infections in laboratory animals. In our laboratory animal facility, B. bronchiseptica was isolated from 21 of 27 apparently healthy rabbits obtained from a breeding farm contaminated with B. bronchiseptica. Restriction fragment length polymorphism (RFLP) analysis showed that the flagellin genotype of isolates from the laboratory animal facility and breeding farm was type A, which is seen relatively frequently in rabbits in Europe. To examine its pathogenicity, guinea pigs, rats, and mice were inoculated intranasally with a representative strain isolated in the laboratory animal facility. Following inoculation of 107 colony forming unit (cfu), severe inflammation was observed in the lungs of guinea pig and mice, although the inflammation was less severe in rats. The strain was recovered from the trachea and lungs of these species after inoculation with lower dose such as 103 or 104 cfu. These results suggest that the isolated strain causes respiratory tract infection in guinea pigs, rats, and mice, and that its pathogenicity higher in mice than in rats. This study extends our knowledge of interpreting the microbiologic status of laboratory animals, which will contribute to the development of reliable and reproducible animal experiments.  相似文献   
59.
We previously reported that synthetic peptides, RLYLRIGRR-NH2 (peptide A) and RLRLRIGRR-NH2 (peptide B), derived from the beetle Allomyrina dichotoma defensin, showed antimicrobial activity against both Gram-positive and negative bacteria and suppressed lipopolysaccharide (LPS)-induced tumor necrosis factor-alpha (TNF-alpha) mRNA expression in a murine macrophage cell line. In this study, inhibitory effects of these peptides in LPS-induced mouse peritoneal macrophage activation were investigated. The supplement of peptide A to macrophages cultured with LPS resulted in a significant decrease in nitric oxide and TNF-alpha production. Furthermore, NF-kappaB activation was also blocked by addition of peptide A. These results indicated that peptide A blocked macrophage activation induced by LPS.  相似文献   
60.
A species of sucking louse, Neohaematopinus callosciuri, was found for the first time in Japan. The species was found on an invasive species of squirrel, Pallas squirrel, Callosciurus erythraeus, in the Kamakura district, Kanagawa Prefecture, Japan. A total of 52 lice were obtained from 22 of 104 squirrels captured. The lice were about three times more prevalent in male squirrels than in females and were detected most frequently in the winter. As N. callosciuri has never been reported on wild animals in Japan, this species probably was introduced into Japan along with their host, Pallas squirrels.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号