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   177篇
  免费   21篇
  国内免费   14篇
耳鼻咽喉   1篇
儿科学   2篇
妇产科学   1篇
基础医学   34篇
口腔科学   3篇
临床医学   12篇
内科学   37篇
皮肤病学   5篇
神经病学   10篇
特种医学   7篇
外科学   22篇
综合类   20篇
预防医学   7篇
眼科学   1篇
药学   20篇
中国医学   1篇
肿瘤学   29篇
  2023年   1篇
  2022年   8篇
  2021年   16篇
  2020年   14篇
  2019年   27篇
  2018年   10篇
  2017年   7篇
  2016年   10篇
  2015年   8篇
  2014年   9篇
  2013年   8篇
  2012年   3篇
  2011年   6篇
  2010年   5篇
  2009年   9篇
  2008年   7篇
  2007年   3篇
  2006年   5篇
  2005年   1篇
  2004年   1篇
  2003年   1篇
  2002年   1篇
  2000年   1篇
  1999年   1篇
  1998年   2篇
  1996年   1篇
  1995年   1篇
  1991年   2篇
  1987年   1篇
  1985年   3篇
  1984年   8篇
  1983年   4篇
  1982年   5篇
  1981年   3篇
  1980年   5篇
  1979年   5篇
  1978年   3篇
  1977年   1篇
  1976年   4篇
  1975年   1篇
  1974年   1篇
排序方式: 共有212条查询结果,搜索用时 15 毫秒
1.
A 15-fold increase in the prevalence of ankylosing spondylitis in a group of 223 men with permanent cardiac pacemakers has recently been demonstrated. In this study of the same patient group, the prevalence of other related rheumatic syndromes was investigated by clinical examination and HLA typing. The clinical picture and electrocardiographic features of all patients with HLA B27-associated rheumatic disease (seronegative spondarthritis) were analyzed. Altogether 28 patients, 12.6 percent (95 percent confidence limits: 8.2 to 17.0 percent), fulfilled inclusion criteria for seronegative spondarthritides; 15 had ankylosing spondylitis. The seronegative spondarthritides previously had been diagnosed in less than 50 percent of the patients. Twenty-two (85 percent) of the 26 HLA-typed patients were B27-positive, implying a very strong association with this genetically determined cell surface protein. Patients with severe bradyarrhythmias associated with the seronegative spondarthritides were thus found to constitute a large proportion of the 223 men with permanent pacemakers. A high frequency of aortic regurgitation and all kinds of bradyarrhythmias were found. Twenty patients had complete heart block--in a majority, occurring intermittently, but otherwise without distinguishing features.  相似文献   
2.
Background: Gout is an inflammatory disease in which genetic factors play a role. ABCG2 is a urate transporter, and the Q141K and Q126X variants of ABCG2 have been associated with a risk of developing gout, though previous studies of these associations have been inconsistent. Therefore, we conducted a meta-analysis to explore the relationship between these genetic variants and gout. Methods: We examined 8 electronic literature databases. In total, 9 eligible articles on the associations between the Q141K (rs2231142) and Q126X (rs72552713) variants and gout risk, including 11 case-control studies were selected. We used odds ratios (OR) and 95% confidence intervals (CI) to assess the strength of these relationships in dominant, recessive, and co-dominant models. Results: This study included 6652 participants (2499 gout patients and 4153 controls). The Q141K variant was found to significantly increase the risk of gout in Asians (dominant model: OR=2.64, 95% CI=2.04-3.43, P=0.02 for heterogeneity; recessive model: OR=3.19, 95% CI=2.56-3.97, P=0.28 for heterogeneity; co-dominant model: OR=1.37, 95% CI=1.18-1.59, P=0.09 for heterogeneity) and other populations (dominant model: OR=1.85, 95% CI=1.20-2.85, P<0.0001 for heterogeneity; recessive model: OR=3.78, 95% CI=2.28-6.27, P=0.19 for heterogeneity; co-dominant model: OR=1.48, 95% CI=1.26-1.74, P=0.19 for heterogeneity). The Q126X variant also significantly increased the risk of gout in Asians (dominant model: OR=3.87, 95% CI=2.07-7.24, P=0.06 for heterogeneity). Conclusions: These results suggest associations between the rs2231142 and rs72552713 ABCG2 gene polymorphisms and gout risk, which led to unfavorable outcomes. However, studies with larger sample sizes and homogeneous populations should be performed to confirm these results.  相似文献   
3.
 目的:研究血清miR-141在前列腺癌中的表达及临床意义。方法:采用实时荧光定量PCR检测75例前列腺癌和52例良性前列腺增生(BPH)患者,以及40例健康对照血清miR-141的相对表达水平。结果:前列腺癌血清miR-141的表达量较BPH和健康对照增高,差异有统计学意义(P<0.01)。但miR-141在BPH组和对照组中的表达差异无统计学意义(P>0.05)。ROC曲线显示miR-141能够较好地区分前列腺癌与BPH(或健康对照),曲线下面积分别为0.785(95%CI∶0.689~0.823)和0.801(95%CI∶0.723~0.868)。血清miR-141表达与Gleason积分、临床分期和骨转移相关(均P<0.05),随着临床分期的增加,miR-141的表达水平增加;但miR-141表达量与患者年龄、肿瘤复发和血清前列腺特异性抗原水平无关(均P>0.05)。结论: 循环miR-141可作为非侵入性诊断前列腺癌并且判断其预后的分子标志物。  相似文献   
4.
5.
Alpinumisoflavone (AIF) as a principal active ingredient of traditional Chinese herb Derris eriocarpa exerts a broad spectrum of anticancer activities against solid tumors. However, little is known about the effect of AIF on papillary thyroid cancer (PTC). Objectives of this study are to investigate the effect of AIF on cell growth, apoptosis, and metastasis of PTC cells and uncover its underlying mechanisms. Results showed that AIF treatment notably suppressed cell viability, migration, invasion, and epithelial–mesenchymal transition (EMT) process, as well as induced apoptotic cell death. In addition, microarray analysis results revealed that miR-141-3p level was dramatically elevated upon AIF insulation, suggesting that miR-141-3p may mediate the suppressive role of AIF against PTC. Moreover, miR-141-3p knockdown effectively reversed the effects of AIF on cell growth, migration, invasion, and EMT, while promoted PTC cell apoptosis escape. Furthermore, in vivo findings also confirmed that the antigrowth and antimetastasis activities of AIF were, at least partly, mediated by upregulation of miR-141-3p. Overall, AIF could serve as a potential anticancer compound for PTC treatment. Anat Rec, 2019. © 2019 American Association for Anatomy Anat Rec, 303:1842–1850, 2020. © 2019 American Association for Anatomy  相似文献   
6.
The mutations in the presenilin 2 (PSEN2) gene as causes of early-onset familial Alzheimer's disease (AD) have never been reported in Asia. We conducted a phenotype and pedigree study by performing neuropathological examination and target region sequencing in a family of 3 generations. Six members in this family developed dementia in their fifth decade and died in their sixth decade. The proband was diagnosed clinically with AD, which was confirmed by an autopsy. Target region sequencing showed a novel missense mutation at codon 141 (N141Y) of the PSEN2 gene that predicts an Asparagine-to-Tyrosine substitution in the affected individuals. The result was validated by Sanger sequencing in 7 family members (2 affected and 5 unaffected). The mutation was absent in the 5 clinically unaffected relatives and 188 control subjects. No influence of the APOE genotype was observed. We are the first to demonstrate a novel PSEN2 N141Y mutation in a Chinese Han family with early-onset AD.  相似文献   
7.
目的:研究microRNA-141(miR-141)表达的调控对人前列腺癌细胞系DU145细胞增殖、周期、凋亡、侵袭和迁移等恶性生物学行为的影响及其作用机制。方法:利用脂质体Lipofectamine2000将miR-141 mimics(miR-141 up组)和miR-141 inhibi‐tiors(miR-141 down 组)分别转染至人前列腺癌DU145细胞中,同时设置未转染组(Control组)和miRNA无义序列转染组(NC组)。qPCR检测转染前后各组DU145细胞中miR-141表达变化,MTT方法检测各组DU145细胞的增殖活力和对顺铂(DDP)作用敏感性变化,流式细胞术检测各组DU145细胞周期和顺铂作用下凋亡率变化,Transwell方法检测各组细胞侵袭和迁移能力的变化,Western blotting检测各组细胞中VEGF、EGFR蛋白表达量变化。结果:与Control组和NC组相比,miR-141 down组DU145细胞中miRNA-141表达水平下降为(0.18±0.08),其细胞增殖活力显著下降而对DDP敏感性显著上升、细胞周期被阻滞于G0+G1期而细胞凋亡率显著上升至(46.67±5.86)%、细胞侵袭率和迁移率分别显著下降至(44.34±8.32)%和(57.73±6.19)%、VEGF和EGFR相对表达量分别下降至(0.47±0.06)和(0.36±0.06)(上述各指标分别P<0.05或P<0.01)。miR-141 up组DU145细胞中miR‐NA-141表达水平上升为(4.23±0.53),其细胞增殖活力显著上升而对DDP敏感性显著下降、细胞周期提前进入S和G2期而细胞凋亡率显著下降至(18.77±4.24)%、细胞侵袭率和迁移率分别显著上升至(89.94±6.34)%和(94.44±5.84)%、VEGF和EGFR相对表达量分别上升至(0.89±0.07)和(0.73±0.06)(上述各指标分别P<0.05或P<0.01)。结论:miR-141在前列腺癌DU145细胞中发挥促癌因子作用,其下调表达能够显著抑制DU145细胞增殖活力、周期、侵袭与迁移,而促进对DDP的敏感性和细胞凋亡,其机制可能与其抑制VEGF和EGFR蛋白表达有关。  相似文献   
8.
It has been reported that two single nucleotide polymorphisms (SNP) Taq1A and -141C Ins/Del in the DRD2 gene may be associated with susceptibility to schizophrenia. Due to inconclusive and mixed results, a meta-analysis was conducted to further clarify the relationship between the two SNP and schizophrenia susceptibility. A systematic literature search for the association of these two SNP with schizophrenia susceptibility was conducted using PubMed, ScienceDirect, Chinese Biomedical Literature Database, and Chinese National Knowledge Infrastructure. Odds ratios (OR) with 95% confidence intervals (CI) were used to assess the strength of the associations reported. A total of 5558 schizophrenic patients and 6792 healthy controls from 31 articles were included in this study. Evidence regarding the association between -141C Ins/Del polymorphism and schizophrenia was found in the allele frequency comparison (Ins versus Del: OR 1.29, 95% CI 1.06–1.57; p = 0.01, Praw = 0.1, PFalse Discovery Rate = 0.023). In ethnic subgroup analysis, the result revealed that the 141C Ins/Del polymorphism was associated with schizophrenia in all genetic models in Asians, but not in Caucasians. For Taq1A polymorphism, a significant association was found in the allele frequency (A1 versus A2: OR 0.71, 95% CI 0.52–0.98, p = 0.03). Stratification by ethnicity indicated an association between the Taq1A polymorphism and schizophrenia in Asians, but not Caucasians. The present study suggests that the -141C Ins/Del polymorphism carries a significantly increased risk of schizophrenia, while the Taq1A polymorphism carries a significantly decreased risk of schizophrenia susceptibility in Asians.  相似文献   
9.
Resistance to HIV protease inhibitors   总被引:4,自引:0,他引:4  
J. H. CONDRA 《Haemophilia》1998,4(4):610-615
Summary. Resistance to the HIV-1 protease inhibitor indinavir involves the accumulation of multiple amino acid substitutions in the viral protease. A minimum of 11 amino acid positions have been identified as potential contributors to phenotypic resistance. Three or more amino acid substitutions in the protease are required before resistance becomes measurable (≥four-fold). Further losses in susceptibility follow the stepwise accumulation of additional amino acid substitutions, indicating that antiviral activity (selective pressure) is maintained despite the appearance of multiple amino acid substitutions in the viral protease. Importantly, the sequential nature of these changes indicates that the effects of these substitutions are additive, and that the evolution of resistance is driven by viral replication. This result has significant implications for therapy. It predicts that viral variants resistant to indinavir are unlikely to pre-exist in protease inhibitor-naive patients, and further, that high-level resistance can only develop if the virus is allowed to replicate in the presence of the drug. The use of indinavir in combination with other antiretroviral agents has been demonstrated to dramatically reduce the incidence of resistance mutations, suggesting that with maximal suppression of viral replication, long-term control of HIV-1 infection may be achievable. Thus, the goal of therapy must be to never to allow the virus to replicate. This can be best accomplished by initiating therapy with a maximally suppressive regimen, to reduce viral replication as much as possible, and by imposing a high genetic barrier to resistance. Previous use of other protease inhibitors or inadequate adherence to therapy may compromise the long-term benefit of indinavir by allowing the virus to gain a foothold through the development of resistance. An understanding of these issues will be critical in realizing the full potential of this potent new drug for the control of HIV-1 infection.  相似文献   
10.
Numerous publications address the skin sensitizing potential of the short chain alkanolamines triethanolamine (TEA), diethanolamine (DEA), monoethanolamine (MEA), which are not skin sensitizing according to animal studies. Regarding TEA, we analysed patch test data of 85 098 patients who had been tested with TEA 2.5% petrolatum by Information Network of Departments of Dermatology (IVDK) to identify particular exposures possibly associated with an elevated risk of sensitization. Altogether, 323 patients (0.4%) tested positive. The profile of patch test reactions indicates a slightly irritant potential rather than a true allergic response in many cases. Although used widely, no exposure associated with an increased risk of TEA sensitization was identified. Therefore, the risk of sensitization to TEA seems to be very low. MEA and DEA were patch tested in a much more aimed fashion in 9602 and 8791 patients, respectively when prevalence of contact allergy was 3.8% and 1.8%. MEA is the prominent allergen in metalworkers with exposure to water‐based metalworking fluids (wbMWFs); DEA is probably used in cutting fluids less frequently nowadays. Chronic damage to the skin barrier resulting from wbMWF, the alkalinity of ethanolamines (increasing from TEA to MEA), and other cofactors may contribute to a notable sensitization risk.  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