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   117篇
  免费   12篇
  国内免费   32篇
  2023年   3篇
  2022年   6篇
  2021年   4篇
  2020年   4篇
  2019年   3篇
  2018年   1篇
  2017年   4篇
  2016年   3篇
  2015年   4篇
  2014年   6篇
  2013年   3篇
  2012年   12篇
  2011年   16篇
  2010年   8篇
  2009年   6篇
  2008年   7篇
  2007年   6篇
  2006年   3篇
  2005年   6篇
  2004年   4篇
  2003年   3篇
  2002年   7篇
  2000年   1篇
  1999年   6篇
  1998年   2篇
  1994年   2篇
  1993年   2篇
  1990年   2篇
  1989年   2篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1982年   3篇
  1981年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1966年   1篇
  1958年   2篇
  1957年   2篇
  1956年   1篇
  1954年   2篇
  1953年   1篇
  1952年   2篇
  1950年   1篇
  1930年   2篇
排序方式: 共有161条查询结果,搜索用时 15 毫秒
111.
目的:探讨甲状腺功能亢进(甲亢)、甲状腺功能减低(甲低)与肝纤维化指标的关系及其可能的机制。方法:采用放射免疫分析法(R1A)检测57例甲亢患者、43例甲低患者、39例甲亢治疗后甲状腺激素正常者和50例健康成人的血清Ⅳ型胶原(1V-C)、Ⅲ型前胶原(PCⅢ)、透明质酸(HA)、层粘连蛋白(LN)、T3、T4、FT3、FT4、TSH、TGA、TMA含量。结果:甲亢患者组血清中1V-C、PCⅢ含量比正常对照组及甲低患者组显著性增高(P〈0.05);治疗后甲状腺激素下降,1V-C、PCⅢ含量也随之下降(与治疗前比较P〈0.01);HA、LN在四组中无显著性差异(P〉0.05),在甲亢治疗前后无显著性差异(P〉0.05)。各项肝纤维化指标与TGA、TMA的阳性率无关。结论:甲亢患者可有不同程度的肝功能损害,血清中甲状腺激素水平增高时,1V-C、PCⅢ水平也增高,在用1V-C、PCⅢ判断肝纤维化时应注意有无甲状腺疾病特别是甲亢。未发现HA、LN含量与甲状腺激素水平的关系。  相似文献   
112.
Variation at five polymorphic microsatellite loci was used to investigate genetic diversity and differentiation of two tetraploid Canarian endemics, Bencomia exstipulata and B. caudata. Data were analysed and are discussed in terms of tetrasomic (autotetraploid) and disomic (allotetraploid) inheritance. In both cases, genetic diversity values were similar to those described in other tetraploid plant species. High genetic differentiation between the only two described natural populations of B. exstipulata was detected (FST = 0.411). Bayesian cluster analysis revealed a geographical structure with distinct genetic groups from each island. High genetic differentiation and low genetic diversity of the B. exstipulata population from Tenerife suggest a recent population bottleneck, perhaps caused by the most recent major volcanic eruption, for this natural locality. This may be heightened by possible inbreeding depression and the monoecy of these species. Polymorphic microsatellite loci were also tested across all species in the Bencomia alliance. These reliably amplified the target sequence, suggesting a high degree of conservation of the sequences flanking the microsatellites. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 429–441.  相似文献   
113.
We report here the new ‘creodont’ Lahimia selloumi gen. et sp. nov. from the late Palaeocene of the Ouled Abdoun Basin (Morocco) as the oldest known Hyaenodontidae with Tinerhodon from the Ouarzazate Basin (Morocco). By contrast to Tinerhodon, Lahimia is unexpectedly derived. Most of its specializations, such as the shortening of the anterior dentition (e.g. loss of P1) and the talonid reduction and simplification, are strikingly shared with Boualitomus from the Ypresian of the Ouled Abdoun Basin, and are distinctive from other hyaenodontids, including ‘proviverrines’. They are interpreted as synapomorphies evidencing a precociously specialized early African hyaenodontid lineage. Although Lahimia and Boualitomus remain known only by the lower dentition, their relationships with Koholia are suggested by comparison of their molar occlusal pattern. Lahimia and Boualitomus are referred to the Koholiinae, which is representative of an old African endemic lineage, as initially recognized. This remarkable lineage is characterized by synapomorphies of Lahimia and Boualitomus, and also by a shared original prevallum/postvallid shearing. The discovery of Lahimia provides direct evidence for the antiquity of the African evolution of the Hyaenodontidae. This is in agreement with an African origin of the Hyaenodontidae, and with the probable diphyletism of the ‘Creodonta’. Lahimia and the Koholiinae, as well as the diversity of the first Laurasian hyaenodontid lineages, emphasize our poor knowledge of the striking early African hyaenodontid radiation.  相似文献   
114.
以烈香杜鹃嫩茎为外植体,应用均匀设计法筛选其最适合的嫩茎基部直接再生芽苗和生根培养基。结果表明,最适合烈香杜鹃嫩茎基部直接再生芽苗的诱导培养基为DR+2.30mg·L-1 TDZ+0.05mg·L-1 IAA+1.80mg·L-1 KT,诱导率为99.6%;生根培养基为1/2DR+0.07mg·L-1 IAA+0.02mg·L-1NAA,生根率达99.7%以上。以再生植株茎节为材料进行快速繁殖,在35d的培养周期内,每段增殖倍数平均达5以上。  相似文献   
115.
目的 电压门控钠通道(voltage-gated sodium channels,VGSCs)表达于胶质瘤U251细胞,并影响U251细胞的增殖、侵袭和凋亡.富含半胱氨酸的颊腺蛋白(cysteine-rich buccal gland protein,CRBGP)是一种从日本七鳃鳗颊腺中分离出来的VGSCs阻断剂.本文...  相似文献   
116.
目的:探讨18F-FDG PET显像和131I-全身扫描(131I-WBS)SPECT显像对分化型甲状腺癌(DTC)术后转移灶的临床诊断价值。方法:对57例外科术后拟行131I治疗的DTC患者行18F-FDG PET全身显像和131I-WBS扫描,观察和记录在糖代谢和碘代谢中DTC转移灶的定位及数量变化,并同时测定甲状腺球蛋白(Tg),促甲状腺激素释放激素(TSH)等实验室检查项目。结果:57例DTC患者18F-FDG PET显像发现真阳性20例、假阳性3例、真阴性31例、假阴性3例,其灵敏度为87.0%,特异性为91.2%。而131I-WBS扫描发现真阳性13例、假阳性2例、真阴性34例、假阴性8例,其灵敏度为61.9%,特异性为94.4%。PET显像和131I-WBS扫描共检出阳性病灶73个,其中淋巴结32个,肺5个,纵隔6个,骨26个,其他部位4个。PET显像发现43个阳性病灶(58.9%),而131I-WBS检出30个(41.1%)。当Tg水平〉10μg/L时,随着Tg在血清含量的增高,两种显像方法的对DTC转移灶的阳性检出率亦随之升高。结论:两种检查对DTC术后转移灶的监测和131I的治疗具有良好的互补性,18F-FDG PET显像在Tg阳性和131I-WBS阴性的患者的转移灶检出上更具有优势,有重要的临床指导意义。  相似文献   
117.
猪CFL2b 基因cDNA克隆初步分析   总被引:5,自引:1,他引:4  
利用基因表达谱芯片分析法筛选出与大白猪高肌肉产量-肌纤维形成有关的CFL2b基因.参考人和小鼠CFL2b基因序列,采用SMART-RACE技术结合EST序列拼接技术,从猪骨骼肌肌肉中首次克隆了猪CFL2b的全长cDNA序列(GenBank登录号EU561660,EU561661),Northern杂交检测CFL2b基因 mRNA.结果表明,猪CFL2b基因含有2个转录本,长转录本3 012 bp,短转录本1 466 bp .CFL2b基因在多种真核生物中都有表达,且编码区序列非常保守,开放式读码框501 bp编码了166个氨基酸的蛋白质.氨基酸序列分析表明,猪CFL2基因与人和小鼠氨基酸同源性分别为100%和99.1%.核苷酸序列相似性分别为88.1%和74.9%.  相似文献   
118.
119.
The presence of anti-alpha-fodrin autoantibodies has been reported to be a highly specific and sensitive test for the diagnosis of Sj?gren's syndrome (SjS). We looked (in Nijmegen) for anti-alpha-fodrin, anti-Ro60, and anti-La autoantibodies in a cohort of 51 patients with rheumatic diseases (primary SjS [21], secondary SjS 6, rheumatoid arthritis [RA] 12, systemic lupus erythematosus [SLE] 6, and scleroderma 6) and in 28 healthy subjects, using ELISA, immunoblotting, and immunoprecipitation. The same samples were analyzed with an alternative anti-alpha-fodrin ELISA in Hanover. The Nijmegen ELISA of the sera from primary SjS showed sensitivities of 43% and 48% for IgA- and IgG-type anti-alpha-fodrin antibodies, respectively. The Hanover ELISA showed sensitivities of 38% and 10% for IgA- and IgG-type anti-alpha-fodrin antibodies, respectively. The ELISAs for alpha-fodrin showed six (Nijmegen) and four (Hanover) anti-alpha-fodrin-positive RA sera. IgA and IgG anti-fodrin antibodies were also present in four patients with secondary SjS. The sensitivities of Ro60 and La-antibodies in the Nijmegen ELISA were 67% and 62%, respectively. Unlike anti-alpha-fodrin antibodies, all anti-Ro60 and anti-La positive sera could be confirmed by immunoblotting or RNA immunoprecipitation. Thus, anti-Ro and anti-La autoantibodies were more sensitive than anti-alpha-fodrin autoantibodies in ELISA and were more frequently confirmed by other techniques. Anti-La antibodies appear to be more disease-specific than anti-alpha-fodrin antibodies, which are also found in RA sera. Therefore, the measurement of anti-alpha-fodrin autoantibodies does not add much to the diagnosis of Sj?gren's syndrome.  相似文献   
120.
A mechanically transmissible virus with isometric particles c. 32 nm in diameter, was isolated from infected watermelons and sweet melons in the People's Democratic Republic of Yemen. Purified virus preparations contained two major sedimenting components with sedimentation coefficients of 61S and 117S. In isopycn ic centrifugation in CsCl the particles formed a single band of buoyant density 1.39 g cm-3. Preparations of virus particles comprised of a single polypeptide of mol. wt c. 22 000 and ssRNA of mol. wt 2.1 × 106. The virus was serologically related to three of six subgroups of tymoviruses tested. The name melon rugose mosaic virus is proposed for this newly described virus.  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