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   79篇
  免费   2篇
林业   5篇
农学   9篇
  18篇
综合类   6篇
农作物   8篇
水产渔业   4篇
畜牧兽医   23篇
园艺   1篇
植物保护   7篇
  2023年   4篇
  2022年   6篇
  2021年   6篇
  2020年   5篇
  2019年   2篇
  2018年   4篇
  2017年   6篇
  2016年   5篇
  2015年   3篇
  2014年   1篇
  2013年   6篇
  2012年   8篇
  2011年   8篇
  2010年   2篇
  2009年   1篇
  2008年   3篇
  2007年   2篇
  2006年   6篇
  2003年   2篇
  2002年   1篇
排序方式: 共有81条查询结果,搜索用时 15 毫秒
61.
A potentially diagnostic 18S rDNA (ribosomal DNA) gene was amplified reliably from red-listed ethnomedicinal species of Myristica and its wild and related genera. Individuals from nine species of Myristicaceae were utilized for the study. The sequences ranged from 1,767 to 1,794 nucleotide (nt) in length. The GC content (%) varied from 52.77 to 51.04. The frequencies (%) of nt were A (23.31), T (23.82), C (24.48) and G (28.39). The alignment of all sequences produced 195/1,516 variable sites and 1,257/1,516 conserved sites. Total numbers of single nucleotide polymorphism (SNP) sites found in the alignment were 146/1,516. Knema andamanica (Warb.) W.J. de Wilde was the most distinct that included 18 variable regions and 15 InDel with 27 SNP sites, specific to this species. The identified regions from nine species of Myristica and its wild and closely related genera were deposited in the GenBank Database (Accession numbers JN228257-JN228265). Comparison of morphological identifications and phylogenetic analysis indicated that the specimens were correctly assigned on the basis of a short stretch of 18S rDNA (~1,600 bp) making this a potentially useful marker for the rapid molecular assignment of an unknown related species also. Significant sequence homology ranging from 72 to 99 % was observed on comparison with 18S rDNA genes of other plants in the public domain. A comparison of intraspecific data information of nine 18S with that of 73 matK and 86 rbcL sequences from GenBank revealed that polymorphism, divergence and conservation is higher in 18S locus for Myristicaceae. Hence these markers may be utilized for phylogenetic analysis, evaluation of species richness during ecological surveys or for environmental assessments. These molecular markers are especially important due to the fact that the species studied are mostly vulnerable and red-listed with limited availability in endangered ecological niches.  相似文献   
62.
Probiotics renowned as valuable microbes serve as a potential alternative to control diseases in aquaculture and are considered as an efficient and environment‐friendly approach to reduce the use of antibiotics. The present study aims at the isolation of putative probiotic bacteria from the intestinal tract of different fish species from the Doaba region of Punjab, India. In this study, isolated bacterial strains were characterized based on their morphological, biochemical and molecular characterization by 16S rRNA gene sequencing, followed by in vitro evaluation of different selection parameters described in FAO/WHO guidelines. A total of 169 different bacterial strains were isolated from the gastrointestinal tract of 52 different fish species. After in vitro evaluation, out of 169 bacterial strains only five bacteria (S3, S7, BDK2', BDK7 and BDK9) identified as Enterococcus and Bacillus species showed antagonistic activity against the fish pathogen Pseudomonas aeruginosa (MTCC 4 673). These isolates were screened based on their response towards bile tolerance, pH tolerance, adhesion and drug susceptibility to different antibiotic discs. And, the in vivo results indicated improved growth and survival against the infection (P. aeruginosa) after oral administration of the probiotics. The observations of in vitro and in vivo evaluation indicate that these isolated probiotic strains serve as effective probiotics and can be used as a novel and safe treatment to cure current issues in aquaculture.  相似文献   
63.
The dichloromethane (MKD) and ethyl acetate (MKE) extracts of Murraya koenigii leaves significantly reduced the body weight gain, plasma total cholesterol (TC) and triglyceride (TG) levels significantly when given orally at a dose of 300 mg/kg/day to the high fat diet (HFD) induced obese rats for 2 weeks. The observed antiobesity and antihyperlipidemic activities of these extract are correlated with the carbazole alkaloids present in them. Mahanimbine (1) when given orally (30 mg/kg/day) also significantly lowered the body weight gain as well as plasma TC and TG levels. These findings demonstrate the excellent pharmacological potential of mahanimbine to prevent obesity.  相似文献   
64.
The US seafood sector is susceptible to shocks, both because of the seasonal nature of many of its domestic fisheries and its global position as a top importer and exporter of seafood. However, many data sets that could inform science and policy during an emerging event do not exist or are only released months or years later. Here, we synthesize multiple data sources from across the seafood supply chain, including unconventional real‐time data sets, to show the relative initial responses and indicators of recovery during the COVID‐19 pandemic. We synthesized news articles from January to September 2020 that reported effects of COVID‐19 on the US seafood sector, including processor closures, shortened fishing seasons and loss of revenue. Concerning production and distribution, we assessed past and present landings and trade data and found substantial declines in fresh seafood catches (?40%), imports (?37%) and exports (?43%) relative to the previous year, while frozen seafood products were generally less affected. Google search trends and seafood market foot traffic data suggest consumer demand for seafood from restaurants dropped by upwards of 70% during lockdowns, with recovery varying by state. However, these declines were partially offset by an increase (270%) in delivery and takeout service searches. Our synthesis of open‐access data sets and media reports shows widespread, but heterogeneous, ramifications of COVID‐19 across the seafood sector, implying that policymakers should focus support on states and sub‐sectors most affected by the pandemic: fishery‐dependent communities, processors, and fisheries and aquaculture that focus on fresh products.  相似文献   
65.
To determine the prevalence of Cryptosporidium spp. and other zoonotic enteric parasites in a sample of domestic dogs and cats in the Niagara region, Ontario, 5 of 26 clinics invited by mail survey reported their parasitological findings over 24 months. Stool samples collected by 1 clinic over 68 days were investigated for parasites by using several techniques (fecal concentration, acid-fast staining, and a Cryptosporidium immunoassay). The 5 clinics that provided data indicated Toxocara spp. as the most frequent finding. Parasitological study of 111 stool samples showed a high overall positivity rate in samples from both dogs (40%) and cats (36.6%). Cryptosporidium spp. antigen was detected in 7.4% and 7.3%, Toxocara spp. in 14.2% and 12.2%, and Giardia spp. 7.1% and 2.4% of dog and cat samples, respectively. The high prevalence of zoonotic parasites in the Niagara region is important, and increased awareness of their potential threat to human health is necessary. Additionally, further research into the zoonotic capacity of Cryptosporidium spp. and Giardia spp. is necessary.  相似文献   
66.
67.
A novel Salmonella Enteritidis (SE) vaccine candidate strain, JOL919 was constructed by deleting the lon and cpxR genes from a wild-type SE using an allelic exchange method. The study was carried out to evaluate the strain as a vaccine candidate against salmonellosis. The strain showed the enhanced macrophage invasion, early bacterial clearance and higher immune responses as compared to the other mutants, JOL917 (Δlon) and JOL918 (ΔcpxR), and the wild type. In further analysis, the chickens immunized with JOL919 showed a significant increase in plasma IgG and intestinal secretory IgA levels, which was an indication of robust humoral and mucosal immune responses induced by the candidate. The lymphocyte proliferation response and CD45(+)CD3(+) T cells, associated with an activation of T helper and cytotoxic cells, were also significantly increased in the immunized group, which indicated that the candidate also induced cellular immune responses. The immune cell influx into caecal tissues analyzed by immunohistochemistry showed that CD8(+) T cells were predominated in the immunized group, suggesting that the candidate can clear the invaded pathogen in the intestines by a more direct way involving cytotoxic activity. By the examination of the protection efficacy measured by observations of gross lesions in the organs and bacterial recovery, the candidate can provide an efficient protection upon virulent challenge.  相似文献   
68.
The study was conducted to establish the ultrasonographic features of the healthy and impacted omasum in cows and buffaloes. Scanning was done using a 3.5 MHz microconvex transducer. In healthy buffaloes, the omasum could be scanned at the eighth to ninth intercostal space as a round or oval structure having thick echogenic wall with echogenic leaves. Gradual slow movements of omasal leaves could also be seen in real-time B-mode. The omasum appeared to be very clear, large, and close to the transducer at the start of the omasal contraction, and as the contraction progressed the omasum retracted away from the transducer and became very small. In healthy cows the omasum was seen as a crescent-shaped structure with an echogenic wall. The contents of the omasum or omasal leaves could not be visualized. Omasal contractility was not as prominent as in buffaloes. In buffaloes, the impacted omasum appeared amotile, the omasal leaves were not visible, and the omasum as a whole gave a prominent distal acoustic shadow. In cows, the impaction could be diagnosed based on amotile omasum covering a large area on the right side. Ultrasonography was found to be helpful in subjective assessment of omasal impaction but could not aid in diagnosing the severity of impaction.  相似文献   
69.
There are sporadic reports on urban forests in Indian cities. Nagpur is one of the greenest cities of India with 18 per cent of its area under forests and plantations, 17 per cent under cultivation and 2 per cent under water bodies. The present study showed that natural vegetation of the city is very well diversified with a representation of 59 per cent vegetation including 124 trees species belonging to 38 families as compared with the overall district vegetation statistics. Air quality in the city is relatively better with lower SO2 (6 μg/m3), NO2 (18 μg/m3) and Respirable Suspended Particulate Matters (RSPM, 53 μg/m3) as against National Ambient Air Quality Standards (2009) for cities in India of 80, 80 and 100 μg/m3, respectively. It was also noted that the diversity in natural forests which are being protected is greater than the plantations undertaken by the civic authorities and private sector efforts. The study thus demonstrated the positive relationship of the city with diversified vegetation cover for cleaner environment. The analysis is expected to guide formulation of strategies for maintaining green space in the city.  相似文献   
70.
Escherichia coli heat-labile enterotoxin B subunit (LTB) protein is a potent mucosal adjuvant. In this study, the effect of an attenuated Salmonella secreting LTB protein as an adjuvant strain (JOL1228) for a live Salmonella Enteritidis (SE) vaccine candidate (JOL919) was evaluated. In a single immunization experiment, chickens immunized with a mixture of JOL919 (5 parts) and JOL1228 (1 part) showed enhanced mucosal and cellular immune responses and efficient protection against salmonellosis as compared to those unimmunized control chickens. In further analysis, chickens were primed at one day of age and were boosted at the fifth week of age to prolong immune responses and to maximize the protection efficacy against salmonellosis. The immunized groups B (prime and booster with JOL919), C (prime with JOL919-JOL1228 mixture and booster with JOL919), and D (prime and booster with JOL919-JOL1228 mixture) showed significantly higher humoral and cellular immune responses as compared to those in the unimmunized control group A. In addition, immunized groups C and D showed fewer gross lesions in the liver and spleen and a lower number of SE-positive organs, with the lowest bacterial counts in the SE challenge strain as compared to the control group. These results indicate that SE vaccination with the LTB strain can have an adjuvant effect on the vaccine candidate by enhancing immune responses, and that a prime-boost strategy with the addition of the adjuvant strain can efficiently protect birds against salmonellosis.  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