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   80篇
  免费   4篇
林业   5篇
农学   2篇
  23篇
综合类   3篇
农作物   6篇
水产渔业   2篇
畜牧兽医   35篇
园艺   4篇
植物保护   4篇
  2021年   2篇
  2020年   2篇
  2019年   1篇
  2018年   2篇
  2017年   3篇
  2016年   2篇
  2015年   3篇
  2014年   1篇
  2013年   7篇
  2012年   5篇
  2011年   6篇
  2010年   5篇
  2009年   8篇
  2008年   5篇
  2007年   8篇
  2006年   2篇
  2005年   8篇
  2004年   7篇
  2003年   3篇
  2002年   2篇
  1991年   2篇
排序方式: 共有84条查询结果,搜索用时 625 毫秒
61.
The importance of honey has been recently increased because of its nutrient and therapeutic effects, but the adulteration of honey in terms of botanical origin has increased, too. The floral origin of honeys is usually determined using melisso-palynological analysis and organoleptic characteristics, but the application of these techniques requires some expertise. A number of papers have confirmed the possibility of characterizing honey samples by selected chemical parameters. In this study high-resolution nuclear magnetic resonance (HR-NMR) and multivariate statistical analysis methods were used to identify and classify honeys of five different floral sources. The 71 honey samples (robinia, chestnut, citrus, eucalyptus, polyfloral) were analyzed by HR-NMR using both 1H NMR and heteronuclear multiple bond correlation spectroscopy (HMBC). Spectral data were analyzed by application of unsupervised and supervised pattern recognition and multivariate statistical techniques such as principal component analysis (PCA) and general discriminant analysis (GDA). The use of 1H-(13)C HMBC coupled with appropriate statistical analysis seems to be an efficient technique for the classification of honeys.  相似文献   
62.
Colletotrichum gloeosporioides is the causal agent of Camellia oleifera anthracnose, mainly infecting fruits and leaves. The fungus secretes degrading enzymes to destroy the cuticle of aerial plant parts and help infect the host successfully. To validate whether a cutinase gene (CglCUT1) was required for cutinase activity and pathogenicity of C. gloeosporioides, the CglCUT1 gene was cloned and analyzed. The characterization of CglCUT1 predicted protein suggests that the cloned DNA encoded a cutinase in C. gloeosporioides affecting C. oleifera. The CglCUT1 showed a high homology to those from C. gloeosporioides causing papaya anthracnose and C. capsici causing pepper anthracnose, as well as those of other ascomycetes. The whole CglCUT1 gene was knocked-out and the knockout mutant (?CglCUT39) was subsequently complemented using Agrobacterium tumefaciens mediated transformation. The knockout transformants exhibited significant decreases in cutinase activity and virulence compared with the wild-type strain. The complemented transformants of the disrupted transformant ?CglCUT39 showed a significant increase in cutinase activity and virulence compared with the disrupted transformant ?CglCUT39. This study suggests that the CglCUT1 gene has a positive effect on fungal virulence of the hemibiotrophic C. gloeosporioides on C. oleifera.  相似文献   
63.

Background

Since 1999, field evidence of transplacental infection by porcine circovirus type 2 (PCV2) and reproductive failure has been reported in pigs. The objective of this study was to evaluate the clinical and pathological consequences of PCV2 infection in conventional PCV2-seropositive gilts by insemination with PCV2b-spiked semen.

Results

Six PCV2 seropositive gilts were inseminated with PCV2b-supplemented semen (infected) and three animals with semen and cell culture medium (controls). Only three out of the six infected animals were pregnant by ultrasonography on day 29 after insemination, while two out of the three controls were pregnant. One control gilt aborted on day 23 after insemination but not due to PVC2. Viraemia was demonstrated in four out of six infected and in one control gilt that became infected with PCV2a. Anti-PCV2 antibody titres showed dynamic variations in the infected group throughout the study. Among infected gilts, the animal with the lowest anti-PCV2 titre (1/100) at the beginning of the experiment and another that reached a similar low value during the experiment showed evident seroconversion over time and had also PCV2 positive foetuses. One placenta displayed mild focal necrosis of the chorionic epithelium positively stained by immunohistochemistry for PCV2 antigen.

Conclusions

PCV2-seropositive gilts can be infected with PCV2 after intrauterine exposure and low maternal antibody titre may increase the probability of a foetal infection.  相似文献   
64.
Canine erythrocytes were loaded with the antineoplastic drug doxorubicin and then treated with 0.16% glutaraldehyde. This procedure has been previously shown to slow down the efflux of doxorubicin from erythrocytes and to result in the selective targeting of the carrier erythrocytes to liver. Three dogs were treated each with 2 different schedules of IV bolus administration of doxorubicin (0.4 mg/kg of body weight): free drug and doxorubicin encapsulated in glutaraldehyde-treated erythrocytes. The 2 treatments yielded consistent differences in the plasma pharmacokinetic properties of doxorubicin and of its only metabolite, doxorubicinol. A triphasic exponential decay of doxorubicin plasma concentrations was observed on injection of the free drug. Conversely, in the case of erythrocyte-encapsulated doxorubicin, 4 phases of plasma concentrations of doxorubicinol were found. The plasma concentrations of doxorubicinol, after a steady increase during the first hour, followed patterns of decay comparable to those of the parent drug. On the basis of the kinetic variables calculated with the 2 administration schedules, area under curve concentrations of plasma doxorubicin were 136 micrograms.h/L (free infusion) and 734 micrograms.h/L (erythrocyte-encapsulated drug). Significant alterations of hematologic and hematochemical factors were not observed in the 3 dogs during and after the 2 treatments. On the basis of our findings, doxorubicin-loaded and glutaraldehyde-treated erythrocytes may potentially be used in the treatment of systemic and hepatic tumors in dogs.  相似文献   
65.
66.
Coccidiosis of chickens is one of the commonest and economically most important parasitic diseases of poultry worldwide. Given the limitations of traditional approaches, molecular tools have been developed for the specific diagnosis of coccidiosis. Recently, a polymerase chain reaction (PCR)-based capillary electrophoresis (CE) method, employing genetic markers in the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA, was established for both analytical and diagnostic purposes. The application of this method to investigate the epidemiology of coccidiosis and genetic structures of Eimeria populations on commercial chicken establishments has discovered genetic variants of Eimeria (i.e., new operational taxonomic units OTU-X, OTU-Y and OTU-Z) which were (based on CE analysis) distinct from those of species of Eimeria identified previously in chickens in Australia. The present characterization of these OTUs, based on their ITS-2 sequences and phylogenetic analyses of selected sequence data, provides first evidence to support that OTU-X represents a population variant of Eimeria maxima, and that OTU-Y and OTU-Z represent cryptic species of Eimeria. Further biological and genetic studies are needed to rigorously test these proposals and establish the specific status of these OTUs and their importance as pathogens in chickens. An understanding of the epidemiology of these population variants or cryptic species in Australia is central to designing and implementing effective vaccination and control strategies.  相似文献   
67.
68.
Ghrelin is involved in many biological processes, ranging from appetite regulation and the release of growth hormone to the regulation of gastrointestinal motility and secretion processes. Ghrelin expression is not homogenously distributed throughout the gastrointestinal tract; expression is species-specific and can also depend on the animal age. This study was performed to investigate ghrelin immunolocalization in the gastrointestinal tract of pigs at different ages: 1 day (birth), 28 days (weaning), 2 months, 4 months, and 7 months (pre-puberty). Tissue samples were collected along the entire gastrointestinal tract and were examined by immunohistochemistry and double-immunofluorescence. Histometry was performed by counting the number of endocrine ghrelin immunopositive cells in the gastrointestinal mucosa. Ghrelin was found to be present along the swine alimentary canal from the stomach to the caecum. In all regions of the alimentary canal of the animals studied, ghrelin-immunoreactive (IR) cells co-localized with chromogranin-A and were therefore identified as endocrine cells. In the gastric fundus, ghrelin-immunoreactivity was partially detected in co-localization with H-K-adenosine triphosphatase and pepsinogen. Ghrelin-IR endocrine cells were abundant in the oxyntic mucosa but less present in the small intestine and rare in the large intestine. The cell density of the ghrelin-IR endocrine cells was lowest in the oxyntic mucosa of 1-day-old pigs. We can conclude that gastric ghrelin expression is not related merely to age but could also potentially be influenced by food intake.  相似文献   
69.
An EDTA‐anticoagulated blood sample collected from a 1.5‐year‐old, intact male, English Bulldog was submitted for a CBC. The CBC data and blood smear evaluation revealed borderline high hematocrit (54%, reference interval 37–55%), inappropriate rubricytosis, moderate leukopenia due to both mature neutropenia and lymphopenia, and mild thrombocytopenia. Numerous leukocytes showed evidence of karyolysis, pyknosis, and karyorhexis, and apoptotic bodies were frequent in the background. Many neutrophils had botryoid nuclei characterized by increased numbers of nuclear segments radially arranged with spoke‐like, delicate chromatin filaments connecting the segments centrally. The finding of botryoid nuclei and inappropriate rubricytosis was indicative of severe hyperthermia, such as heatstroke. The dog had been exercised a long time during conditions of high temperature and humidity until he collapsed. The dog was diagnosed with severe heatstroke, hypovolemic shock, disseminated intravascular coagulation, and multiorgan dysfunction syndrome. Despite aggressive treatment, the patient died of cardiopulmonary arrest. Botryoid nuclei are frequent in people with heatstroke. In the authors' experience, botryoid nuclei are seen commonly in dogs with heatstroke, but they have never been reported in veterinary medicine. The presence of petechiation with only mild thrombocytopenia and inappropriate rubricytosis also is suggestive of heatstroke and manifests ongoing life‐threatening vascular derangement.  相似文献   
70.
Hydrophobic polypyrrole-coated fabrics with improved electrical conductivity were produced embedding oleic acid as counter-ion. Hydrophobisation of polypyrrole was carried out by means of an ion exchange process after deposition of polypyrrole on cotton fabrics. The fabrics coated with oleic acid-doped polypyrrole showed contact angle of 111°, drop absorption time of 7 minutes and high water repellence, while electrical conductivity increased of ~2 times and heat generation improved, too. Moreover, oleic acid demonstrated a great stability as counter-ion in polypyrrole matrix being present also after washing.  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