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   229篇
  免费   16篇
耳鼻咽喉   9篇
儿科学   38篇
妇产科学   9篇
基础医学   50篇
临床医学   9篇
内科学   48篇
皮肤病学   4篇
神经病学   8篇
特种医学   1篇
外科学   22篇
综合类   2篇
预防医学   14篇
药学   13篇
肿瘤学   18篇
  2024年   1篇
  2023年   1篇
  2022年   2篇
  2021年   4篇
  2018年   3篇
  2016年   3篇
  2015年   2篇
  2014年   2篇
  2013年   5篇
  2012年   6篇
  2011年   6篇
  2010年   4篇
  2009年   8篇
  2008年   11篇
  2007年   16篇
  2006年   19篇
  2005年   17篇
  2004年   11篇
  2003年   13篇
  2002年   16篇
  2001年   16篇
  2000年   12篇
  1999年   11篇
  1998年   2篇
  1997年   4篇
  1996年   3篇
  1995年   3篇
  1994年   4篇
  1993年   1篇
  1992年   3篇
  1991年   4篇
  1990年   2篇
  1989年   3篇
  1988年   2篇
  1987年   2篇
  1986年   4篇
  1985年   2篇
  1984年   2篇
  1983年   1篇
  1979年   2篇
  1978年   1篇
  1975年   3篇
  1974年   1篇
  1971年   1篇
  1969年   2篇
  1968年   3篇
  1967年   1篇
排序方式: 共有245条查询结果,搜索用时 31 毫秒
101.
One hundred and seventy-three Streptococcus pneumoniae strains isolated from surveillance studies conducted in daycare centres were studied. The mefE, erm and tet(M) genes were detected in 16.2, 45.1 and 47.4% of isolates respectively. Agreement between PCR results and antibiotic susceptibility patterns was 100%. Macrolide resistance was due to the presence of erm in 73.6% of strains and to the presence of mefE in the remaining 26.4%. All tetracycline resistant strains carried the tet(M) gene. erm was associated with tet(M) in 98.7% of strains, whereas no isolate carrying mefE carried tet(M). A significant association was found between mefE and serogroup 6 (P < 0.0005) and between erm and tet(M) and serogroup 19 (P < 0.00001).  相似文献   
102.
103.
Summary The consequences at the cardiac level of adriamycin treatment alone or in association with the cardiac glycoside beta-methyldigoxin, were evaluated with reference to the PEP/LVET ratio, heart rate, and minimum blood pressure. The variation usually seen in the PEP/LVET ratio when adriamycin is administered alone was not observed when pretreatment with beta-methyldigoxin was also given. A similar situation is found with variations in blood pressure and heart rate. From a pharmacokinetic point of view, this treatment scheme does not seem to affect the general behavior of the antibiotic.  相似文献   
104.
Six new galactoglycerolipid analogs, in which one or two 4-methylpentanoyl or trans-2-butenoyl groups are linked to the 2-O-beta-D-galactosylglycerol skeleton, were tested for their anti-tumor-promoting activity using a short-term in vitro assay for Epstein-Barr virus early antigen (EBV-EA) activation. All these compounds were more active than their linear or saturated reference compounds in inhibiting the EBV activation promoted by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA), the diester 1-O-(4-methylpentanoyl)-2-O-[6-O-(4-methylpentanoyl)-beta-D-galactopyranosyl]-sn-glycerol resulting the most active glycoglycerolipid analog till now tested. Four compounds (three butenoates and one 4-methylpentanoate), when tested in the in vivo two-stage carcinogenesis test, exhibited also inhibitory effects on mouse skin tumor promotion.  相似文献   
105.
Summary Skin biopsies from patients with pseudoxanthoma elasticum (PXE) were studied by electron microscopy either before or after selective digestions with collagenase, elastase, trypsin, hyaluronidase, chondroitinase AC and ABC, with the aim of identifying an eventual organic component associated with mineralization within the elastin fibers and the chemical nature of the enormous aggregates of filaments very often associated with, but distinct from mineralized elastin fibers. The results obtained, on both embedded thin sections and fresh tissue fragments, showed that (1) elastin fibers, whether mineralized or not, were sensitive only to elastase, and they did not contain significant amounts of materials different from elastin that could be accounted for by ion precipitation; (2) the aggregates of microfilaments in strict connection with altered elastin fibers were mostly sensitive to elastase and hyaluronidase, were partially removed by trypsin and chondroitinase, and were not modified by collagenase, which seems to indicate that the microfilaments consist mainly of abnormally aggregated elastin molecules together with low sulfated proteoglycans. It may be concluded that PXE is a complex genetic disorder of the connective tissue, and that mineralization of elastin is only one of the alterations of the extracellular matrix.  相似文献   
106.
BACKGROUND: In head and neck squamous cell carcinoma, distinguishing second primary tumours and recurrences may help to orient clinical decisions concerning therapy. PATIENTS AND METHODS: A panel of eight microsatellite markers was used to analyse the loss of heterozygosity and genomic instability in a selected group of 32 patients experiencing a recurrence after having undergone surgery for oral or oropharyngeal carcinoma, in order to establish the clonality and origin of the recurrence. RESULTS: Twenty-three patients showed genetic changes in primary and/or relapsing tumour DNA: clonally-related patterns were detected in six cases, whereas the different patterns between paired tumours indicated the presence of a second primary tumour in 17 cases. None of the markers was informative in nine cases. CONCLUSION: Our observations suggest that only a small proportion of patients have primary and secondary tumours developing from a single contiguous altered field (thus indicating a common clonal origin), whereas the metachronous tumour arises in unrelated fields in the majority of cases.  相似文献   
107.
Connective tissue shows peculiar and complex age-related modifications, which can be, at least in part, responsible for altered functions and increased susceptibility to diseases. Food restriction has long been known to prolong life in rodents, having antiaging effects on a variety of physiologic and pathologic processes. Therefore, the aorta has been investigated in rats fed normal or hypocaloric diet, from weaning to senescence. Compared with controls, caloric-restricted animals showed less pronounced age-dependent alterations such as elastic fiber degradation, collagen accumulation and cellular modifications. Immunocytochemical analyses revealed that elastic fibers were positively labelled for biglycan, decorin, ApoB100 (LDL), ApoA1 (HDL) and elastase and that the intensity of the reactions was time- and diet-dependent. With age, the major changes affecting aortic elastic fibers were increased positivity for decorin, LDL and elastase. Compared with age-matched normal fed rats, caloric restricted animals revealed lower content of LDL, decorin and elastase and higher positivity for HDL. These data suggest that a caloric restricted diet might influence the aging process of the arterial wall in rats, delaying the appearance of age-related degenerative features, such as structural alterations of cells and matrix and modified interactions of elastin with cells and with other extracellular matrix molecules.  相似文献   
108.
We report our experience with Chromogenic in Situ Hybridization (CISH) for the evaluation of HER2 amplification on 55 cases of formalin-fixed, paraffin-embedded invasive breast carcinomas of different histology. All the results were corrected for chromosome 17 aneusomy and compared with immunohistochemistry (IHC); a subset of cases was compared to FISH. Thirty-one of 32 cases in which FISH and CISH were performed yielded the same results. CISH and IHC showed a good concordance in the 0/1+ and 3+ category, while a poor agreement with weakly protein overexpression was confirmed. Chromosome 17 analysis was necessary in cases with a low number of HER2 gene copies. CISH is a useful tool to evaluate breast cancer HER2 status that can be easily implemented in a laboratory of surgical pathology.  相似文献   
109.
GITR (glucocorticoid-induced TNFR family related gene) is a member of the TNFR superfamily (TNFRSF) that is expressed in different cell types, including T lymphocytes. Because of a high homology in its cytoplasmic region with other known costimulatory members of the TNFRSF, we investigated whether GITR played a costimulatory role in T lymphocyte subpopulations. Our results show that the proliferation response of CD8+ and CD4+ peripheral T cell subpopulations was potentiated when a GITR costimulus was added to an anti-CD3 stimulus. Furthermore, expression of the main activation-induced receptor (IL-2Ralpha) and production of IL-2 and IFN-gamma were increased more with a GITR costimulus than with anti-CD3 alone. GITR stimulation also enhanced anti-CD3-induced ERK phosphorylation, suggesting that GITR is involved in MAPK-pathway activation. Interestingly, CD4+CD25+ regulatory T cell (Treg cell) proliferation was triggered by the GITR costimulus; Treg cell proliferation was paralleled by the loss of the anergic phenotype and suppressor activity. Nevertheless, unstimulated GITR(-/-) CD4+CD25+ and GITR(+/+) CD4+CD25+ cells were equally able to exert suppressor activity on CD4+CD25- responder cells. These results indicate a novel function for GITR as costimulatory molecule of T cell subsets.  相似文献   
110.
The phenotype of cytosolic Low Molecular Weight Protein Tyrosine Phosphatase (cLMWPTP or ACP1), an enzyme involved in signal transduction of insulin, PDGF and T-cell receptors, has been determined in 71 patients with Crohn's Disease (CD: 37 males and 34 females), 49 patients with Ulcerative Colitis (UC: 27 males and 22 females) and 358 consecutive newborns (194 males and 164 females). cLMWPTP phenotypes showing a high concentration of F isoforms are associated with CD in females and with UC in males. Since PTPases counteract the effects of protein tyrosines kinases, a high concentration of F isoform of cLMWPTP may influence the mucosal response to pathogenic factors, increasing susceptibility to CD in females and to UC in males.  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