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   124篇
  免费   6篇
  2023年   2篇
  2020年   1篇
  2019年   3篇
  2018年   1篇
  2017年   3篇
  2016年   1篇
  2015年   5篇
  2014年   3篇
  2013年   6篇
  2012年   14篇
  2011年   13篇
  2010年   12篇
  2009年   7篇
  2008年   10篇
  2007年   9篇
  2006年   6篇
  2005年   4篇
  2004年   10篇
  2003年   11篇
  2002年   3篇
  2000年   1篇
  1995年   3篇
  1992年   1篇
  1976年   1篇
排序方式: 共有130条查询结果,搜索用时 15 毫秒
41.
The aim of this study is to determine the word frequency for all thirty letters of the Croatian alphabet and to collect normative data for the letter fluency task in Croatian speakers. Ninety two healthy participants were given each of the Croatian letters, and asked to generate as many words as possible in 60 seconds for each letter Results suggested that participants generated most frequently words starting with the letters as follows: "K", "P", "S" and "M".  相似文献   
42.
An efficient one-pot method for the synthesis of novel 9a,11-bridged 15-membered 9a-aza-9-deoxo-9a-homoerythromycin A and its 6-O-methyl analogue has been developed. The novel bicyclic azalide scaffold is characterized by an N′-substituted-2-imino-1,3-oxazolidine moiety bound to a macrolactone ring between positions 9a and 11. Removal of the cladinose sugar from the starting compounds allows easy preparation of a small series of such bicyclic 3-keto and 3,6-hemiketal azalide derivatives. A mechanism for the formation of N′-substituted-2-imino-1,3-oxazolidines is discussed. Antibacterial properties of the prepared compounds were evaluated.  相似文献   
43.
We tested the suitability of the fly transposon Minos, a member of the Tc1/mariner superfamily, for insertional mutagenesis in the mouse germ line. We generated a transgenic mouse line expressing Minos transposase in growing oocytes and another carrying a tandem array of nonautonomous transposons. The frequency of transposition in the progeny derived from oocytes carrying both transgenes is 8.2%. Analysis of the new integration sites shows a high frequency of transpositions to a different chromosome. Thus Minos transposition could be an effective system for insertional mutagenesis and functional genomic analysis in the mouse.  相似文献   
44.
Genome-wide association studies (GWAS) have identified many common variants associated with complex traits in human populations. Thus far, most reported variants have relatively small effects and explain only a small proportion of phenotypic variance, leading to the issues of ‘missing’ heritability and its explanation. Using height as an example, we examined two possible sources of missing heritability: first, variants with smaller effects whose associations with height failed to reach genome-wide significance and second, allelic heterogeneity due to the effects of multiple variants at a single locus. Using a novel analytical approach we examined allelic heterogeneity of height-associated loci selected from SNPs of different significance levels based on the summary data of the GIANT (stage 1) studies. In a sample of 1,304 individuals collected from an island population of the Adriatic coast of Croatia, we assessed the extent of height variance explained by incorporating the effects of less significant height loci and multiple effective SNPs at the same loci. Our results indicate that approximately half of the 118 loci that achieved stringent genome-wide significance (p-value<5×10−8) showed evidence of allelic heterogeneity. Additionally, including less significant loci (i.e., p-value<5×10−4) and accounting for effects of allelic heterogeneity substantially improved the variance explained in height.  相似文献   
45.
The most common histological variants of papillary thyroid carcinoma (PTC), classical (CPTC) and follicular (FPTC), have different diagnostic features, molecular biology, and prognosis. Matrix metalloproteinase-9 (MMP-9) endopeptidase which degrades the components of the extracellular matrix is essential in the invasive growth and metastasizing of malignant tumors. The serum copper (Cu)/zinc (Zn) ratios are sensitive diagnostic and prognostic indicators in oncology since Cu- and Zn-dependent enzymes play important roles in the genesis and the progression of tumors. The aim of this study was to examine the expressions of MMP-9 in tissues of CPTC and FPTC, as well as to determine the Cu/Zn ratios in the same samples. MMP-9 was determined immunohistochemically, and the concentrations of copper and zinc in thyroid tissue were determined by means of flame atomic absorption spectrometry. The results obtained revealed significantly higher expressions of MMP-9 in CPTC in comparison with FPTC, as well as higher Cu/Zn ratios in CPTC than in FPTC. Thus, determining MMP-9 activities and the Cu/Zn ratios could improve the accuracy of the standard histopathological diagnosis of these two types of PTC.  相似文献   
46.
This work presents a study of the effect of foliar and root application of low concentrations (0.1?C10 ??M) of potassium naphthenate on the antioxidative status of cucumber (Cucumis sativus L.), assessed for both local and systemic organs. Changes in the contents of proline and glutathione indicate that the treatment of plants with potassium naphthenate can be characterized as a mild abiotic stress. The antioxidative system of cucumber plants is sensitive to such treatment, since organs directly exposed to the chemical showed a decrease in total antioxidant activities and an increase in peroxidation. In the organs that were not directly treated, an increase in the total antioxidative activity was observed only at the lowest naphthenate concentration while at higher concentrations this activity tended to decrease. As far as the activities of antioxidant enzymes (guaiacol peroxidase, superoxide dismutase, catalase) are concerned, the responses observed differed between enzymes for a given treatment, but showed similar trends within treated local and untreated systemic organs.  相似文献   
47.
The oxidative stress and antioxidant systems in soybean leaves and roots infected with plant pathogen Aspergillus niger were studied following treatment with different concentrations of cholic acid. Several oxidative stress parameters were analyzed: production of superoxide (O2 ·−) and hydroxyl radicals (·OH), lipid peroxidation (LP), and superoxide dismutase (SOD; EC 1.15.1.1) activity, as well as the content of reduced glutathione (GSH). Results showed that inoculation with A. niger led to the increase of O2 ·− production and GSH quantities in leaves and ·OH in roots. The highest activity of SOD occured in infected plants treated with cholic acid in concentrations of 40 and 60 mg L−1 which ultimately led to a decrease in O2 ·− production. Inoculation with Aspergillus in combination with elevated cholic acid concentrations also increased ·OH production which is correlated with increased LP. These results may support the idea of using cholic acid as an elicitor to trigger hypersensitive response in plant cells. Use of cholic acid may also actively contribute to soybean plants defense response against pathogen attack.  相似文献   
48.

Background  

Contagious bovine pleuropneumonia (CBPP) is a mycoplasmal disease caused by Mycoplasma mycoides subsp. mycoides SC (MmmSC). Since the disease is a serious problem that can affect cattle production in parts of Africa, there is a need for an effective and economical vaccine. Identifying which of the causative agent's proteins trigger potentially protective immune responses is an important step towards developing a subunit vaccine. Accordingly, the purpose of this study was to determine whether phage display combined with bioinformatics could be used to narrow the search for genes that code for potentially immunogenic proteins of MmmSC. Since the production of IgG2 and IgA are associated with a Th1 cellular immune response which is implicated in protection against CBPP, antigens which elicit these immunoglobulin subclasses may be useful in developing a subunit vaccine.  相似文献   
49.
One hundred and thirty-one patients on long-term hemodialysis were examined for the presence of clinical symptoms and signs, and for the effects of dialytic age, age and sex on uremic neuropathy. According to dialysis age, the patients were divided into three subgroups: low dialysis age, < 5 years of dialysis (n = 58); intermediate dialysis age, 5-10 years of hemodialysis (n = 39); and high dialysis age, > 10 years of dialysis (n = 34). Two patient subgroups were differentiated according to mean age of 53.2 years: younger (n = 57) and older (n = 74). Clinical grading of uremic neuropathy was based on Nielsen's criteria. The most common symptoms were restless legs syndrome (47%) and cramps (51%). Sensory symptoms were less common in patients on long-term hemodialysis, most common of them being paresthesia (29%) and burning feet syndrome (28%). Abnormal Achilles reflex (53%) and impaired vibration sense (59%) were the most common clinical signs. Clinically manifested uremic neuropathy was present in more than 80% of all study patients, i.e. mild in 41%, and moderate to severe forms of uremic neuropathy according to Nielsen's criteria in 39%. There was no evident effect of dialytic age and sex on the clinical course of uremic neuropathy, however, there was a clear impact of age. It is concluded that long-term hemodialysis does not influence the clinical course of uremic neuropathy unlike evident deterioration of electroneurophysiologic findings.  相似文献   
50.
Context: Genotoxicity assays are widely employed in human biomonitoring studies to assess genetic damage inflicted by genotoxic agents.

Objective: Evaluation of micronuclei (MN) as a screening marker of occupational ionizing radiation (IR) exposure.

Materials and methods: Using micronucleus test, peripheral blood lymphocytes (PBL) of 402 control and exposed subjects were screened for genetic damage.

Results: The mean frequencies of micronucleus test parameters were significantly higher in exposed persons. Increase of micronucleus yield with duration of exposure (DOE) by 0.303MN/year was revealed.

Discussion and conclusion: The obtained data encourage us to consider MN as valuable markers for preventive medical screening of occupationally exposed groups.  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