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   58篇
  免费   4篇
  2022年   1篇
  2021年   4篇
  2017年   1篇
  2015年   3篇
  2014年   1篇
  2013年   1篇
  2012年   3篇
  2010年   2篇
  2009年   5篇
  2008年   2篇
  2007年   3篇
  2006年   5篇
  2005年   3篇
  2003年   1篇
  2000年   2篇
  1999年   2篇
  1998年   6篇
  1997年   2篇
  1995年   2篇
  1993年   1篇
  1991年   1篇
  1984年   1篇
  1982年   1篇
  1981年   3篇
  1979年   1篇
  1978年   2篇
  1968年   1篇
  1966年   1篇
  1965年   1篇
排序方式: 共有62条查询结果,搜索用时 15 毫秒
1.
Reconstructions of the human-African great ape phylogeny by using mitochondrial DNA (mtDNA) have been subject to considerable debate. One confounding factor may be the lack of data on intraspecific variation. To test this hypothesis, we examined the effect of intraspecific mtDNA diversity on the phylogenetic reconstruction of another Plio- Pleistocene radiation of higher primates, the fascicularis group of macaque (Macaca) monkey species. Fifteen endonucleases were used to identify 10 haplotypes of 40-47 restriction sites in M. mulatta, which were compared with similar data for the other members of this species group. Interpopulational, intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of divergence time and branching order incorporating this variation were substantially different from those based on single representatives of each species. We conclude that intraspecific mtDNA diversity is substantial in at least some primate species. Consequently, without prior information on the extent of genetic diversity within a particular species, intraspecific variation must be assessed and accounted for when reconstructing primate phylogenies. Further, we question the reliability of hominoid mtDNA phylogenies, based as they are on one or a few representatives of each species, in an already depauperate superfamily of primates.   相似文献   
2.
A case of gastrointestinal torsion with dilatation in a farm-raised channel catfish (Ictalurus punctatus) was examined at the Thad Cochran National Warmwater Aquaculture Center (Stoneville, Mississippi, USA). The affected fish was a gravid female broodfish, which displayed pale gills and a markedly distended abdomen. Internal examination revealed that the gastrointestinal tract and ovaries were rotated around each other four times in a counterclockwise direction as viewed in right lateral recumbency. The catfish had a markedly distended gastrointestinal tract, pale liver, hypoplastic spleen, hypoplastic swim bladder, and high volume of ascitic fluid. Blood analysis indicated multiple abnormalities, including severe anemia and metabolic acidosis. The etiology of the torsion was uncertain; however, the presence of a hypoplastic swim bladder most likely allowed for increased movement of the gastrointestinal tract and ovaries. When examining cases of abdominal distention in fish, gastrointestinal torsion can be considered among the differential diagnoses.  相似文献   
3.
One of the diseases of veterinary and public health importance affecting the Kafue lechwe (Kobus leche kafuensis) on the Kafue flats is brucellosis, for which only scant information is available. During the 2003 (October), 2004 (December), and 2008 (July-December) hunting seasons in the Kafue flats, we conducted a study to determine the seroprevalence of Brucella spp. in the Kafue lechwe and to evaluate serologic tests for detection of Brucella spp. antibodies in lechwe. The Rose Bengal Test (RBT), competitive enzyme-linked immunosorbent assay (cELISA), and fluorescence polarization assay (FPA) were used. A total of 121 Kafue lechwe were hunted for disease investigations in 2003, 2004, and 2008 in the Kafue Flat Game Management Area. Of these, 21.6%, (95% confidence interval [CI]: 14.2-29.1%) had detectable antibodies to Brucella spp. The Kafue lechwe in Lochnivar National Park had higher antibody results than those in Blue Lagoon National Park (odds ratio=3.0; 95% CI: 0.94-9.4). Infection levels were similar in females (21.6%) and males (21.7%). Results were similar among RBT, FPA, cELISA tests, suggesting that these could effectively be used in diagnosing brucellosis in the Kafue lechwe. Our study demonstrates the presence of Brucella infections in the Kafue lechwe in two national parks located in the Kafue flats and further highlights the suitability of serologic assays for testing the Kafue lechwe. Because the Kafue lechwe is the most hunted wildlife species in Zambia, hunters need to be informed of the public health risk of Brucella spp. infection.  相似文献   
4.
Streptococcus agalactiae is a major piscine pathogen that causes significant morbidity and mortality among numerous species of freshwater, estuarine and marine fishes. Considering the economic importance of fishes susceptible to S. agalactiae throughout the world, an efficacious S. agalactiae vaccine was developed using an extracellular product (ECP) fraction and formalin-killed whole cells of S. agalactiae. A vaccine study was conducted by intraperitoneal (i.p.) injection in Nile tilapia Oreochromis niloticus in order to determine the duration of protection and its correlation to antibodies specific for this pathogen. After 47, 90 or 180 d post-vaccination (DPV), the fish were i.p. challenged with approximately 2.0 x 10(4) S. agalactiae colony-forming units (CFU) fish(-1) to determine the duration of protective immunity. The percent survival in control fish i.p.-injected with sterile TSB was 16,16, and 4% on 47, 90 and 180 DPV, respectively, while the percent survival for the vaccinated fish was 67, 62 and 49%, respectively. The specific mean antibody concentration of the vaccinated fish was significantly higher than that of the control fish, with significant correlation between the ELISA optical density (OD) and protection. These results indicate that the specific antibody has a correlation with protection following immunization with the S. agalactiae vaccine and that the vaccine can confer protection against S. agalactiae up to 180 DPV.  相似文献   
5.
The post-challenge immune and histopathologic responses of hybrid striped bass vaccinated with a DNA vaccine encoding the Mycobacterium marinum Ag85A gene and subsequently challenged with M. marinum were investigated. Juvenile hybrid striped bass Morone saxatilis x M. chrysops were injected intramuscularly with 25 or 50 microg DNA plasmid and developed significant specific protective responses to live bacterial challenge 120 d post-vaccination. Both vaccine groups demonstrated increased survival, reduced splenic bacterial counts, and reduced granuloma formation compared to the control groups 14 d after challenge with approximately 8 x 10(5) cfu M. marinum g(-1) fish body wt. The vaccine groups also developed more rapidly and significantly increased antibody and lymphoproliferative responses post-challenge compared to control groups, and these post-challenge immune responses appear to be vital against M. marinum infection in vaccinated hybrid striped bass. No significant differences in immune responses were recognized between the 25 and 50 microg vaccination groups, and these groups eventually experienced mortalities, splenic bacterial counts, and granuloma formation 28 d post-challenge comparable to those of the control groups at 14 d post-challenge. Therefore, vaccination of hybrid striped bass with a DNA vaccine encoding the M. marinum Ag85A gene provided significant but limited duration of protection against an acute high-dose M. marinum challenge.  相似文献   
6.

Background  

A variety of approaches to understanding protein structure and function require production of recombinant protein. Mammalian based expression systems have advantages over bacterial systems for certain classes of protein but can be slower and more laborious. Thus the availability of a simple system for production and rapid screening of constructs or conditions for mammalian expression would be of great benefit. To this end we have coupled an efficient recombinant protein production system based on transient transfection in HEK-293 EBNA1 (HEK-293E) suspension cells with a dot blot method allowing pre-screening of proteins expressed in cells in a high throughput manner.  相似文献   
7.

Study design

A prospective treatment study with a new brace was conducted Objective. To evaluate radiological and subjective clinical results after one year conservative brace treatment with pressure onto lordosis at the thoracolumbar joint in children with scoliosis and kyphosis.

Summary of background data

Conservative brace treatment of adolescent scoliosis is not proven to be effective in terms of lasting correction. Conservative treatment in kyphotic deformities may lead to satisfactory correction. None of the brace or casting techniques is based on sagittal forces only applied at the thoracolumbar spine (TLI= thoracolumbar lordotic intervention). Previously we showed in patients with scoliosis after forced lordosis at the thoracolumbar spine a radiological instantaneous reduction in both coronal curves of double major scoliosis.

Methods

A consecutive series of 91 children with adolescent scoliosis and kyphosis were treated with a modified symmetric 30 degrees Boston brace to ensure only forced lordosis at the thoracolumbar spine. Scoliosis was defined with a Cobb angle of at least one of the curves [greater than or equal to] 25 degrees and kyphosis with or without a curve <25 degrees in the coronal plane. Standing radiographs were made i) at start, ii) in brace at beginning and iii) after one year treatment without brace.

Results

Before treatment start ??in brace?? radiographs showed a strong reduction of the Cobb angles in different curves in kyphosis and scoliosis groups (sagittal n = 5 all p < 0.001, pelvic obliquity p < 0.001). After one year of brace treatment in scoliosis and kyphosis group the measurements on radiographs made without brace revealed an improvement in 3 Cobb angles each.

Conclusion

Conservative treatment using thoracolumbar lordotic intervention in scoliotic and kyphotic deformities in adolescence demonstrates a marked improvement after one year also in clinical and postural criteria. An effect not obtained with current brace techniques.  相似文献   
8.
The ITS sequences of Acropora spp. are the shortest so far identified in any metazoan and are among the shortest seen in eukaryotes; ITS1 was 70-80 bases, and ITS2 was 100-112 bases. The ITS sequences were also highly variable, but base composition and secondary structure prediction indicate that divergent sequence variants are unlikely to be pseudogenes. The pattern of variation was unusual in several other respects: (1) two distinct ITS2 types were detected in both A. hyacinthus and A. cytherea, species known to hybridize in vitro with high success rates, and a putative intermediate ITS2 form was also detected in A. cytherea; (2) A. valida was found to contain highly (29%) diverged ITS1 variants; and (3) A. longicyathus contained two distinct 5.8S rDNA types. These data are consistent with a reticulate evolutionary history for the genus Acropora.   相似文献   
9.
10.
There is a need for safe medications that can effectively support recovery by treating symptoms of protracted abstinence that may precipitate relapse in alcoholics, e.g. craving and disturbances in sleep and mood. This proof-of-concept study reports on the effectiveness of gabapentin 1200 mg for attenuating these symptoms in a non-treatment-seeking sample of cue-reactive, alcohol-dependent individuals. Subjects were 33 paid volunteers with current Diagnostic and Statistical Manual of Mental Disorders-IV alcohol dependence and a strength of craving rating 1 SD or greater for alcohol than water cues. Subjects were randomly assigned to gabapentin or placebo for 1 week and then participated in a within-subjects trial where each was exposed to standardized sets of pleasant, neutral and unpleasant visual stimuli followed by alcohol or water cues. Gabapentin was associated with significantly greater reductions than placebo on several measures of subjective craving for alcohol as well as for affectively evoked craving. Gabapentin was also associated with significant improvement on several measures of sleep quality. Side effects were minimal, and gabapentin effects were not found to resemble any major classes of abused drugs. Results suggest that gabapentin may be effective for treating the protracted abstinence phase in alcohol dependence and that a randomized clinical trial would be an appropriate next step. The study also suggests the value of cue-reactivity studies as proof-of-concept screens for potential antirelapse drugs.  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