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   3641篇
  免费   209篇
  国内免费   109篇
耳鼻咽喉   6篇
儿科学   61篇
妇产科学   52篇
基础医学   405篇
口腔科学   38篇
临床医学   266篇
内科学   702篇
皮肤病学   42篇
神经病学   208篇
特种医学   19篇
外国民族医学   1篇
外科学   210篇
综合类   353篇
预防医学   209篇
眼科学   74篇
药学   930篇
  1篇
中国医学   132篇
肿瘤学   250篇
  2023年   20篇
  2022年   32篇
  2021年   67篇
  2020年   67篇
  2019年   70篇
  2018年   59篇
  2017年   84篇
  2016年   107篇
  2015年   92篇
  2014年   196篇
  2013年   313篇
  2012年   228篇
  2011年   239篇
  2010年   195篇
  2009年   183篇
  2008年   228篇
  2007年   206篇
  2006年   205篇
  2005年   165篇
  2004年   158篇
  2003年   146篇
  2002年   94篇
  2001年   82篇
  2000年   59篇
  1999年   60篇
  1998年   51篇
  1997年   48篇
  1996年   38篇
  1995年   39篇
  1994年   34篇
  1993年   53篇
  1992年   27篇
  1991年   33篇
  1990年   40篇
  1989年   30篇
  1988年   27篇
  1987年   25篇
  1986年   17篇
  1985年   32篇
  1984年   25篇
  1983年   19篇
  1982年   13篇
  1981年   9篇
  1980年   9篇
  1979年   9篇
  1978年   9篇
  1977年   7篇
  1976年   6篇
  1975年   4篇
排序方式: 共有3959条查询结果,搜索用时 15 毫秒
1.
目的探讨血浆硫氧还蛋白还原酶(TR)在肺癌化疗疗效监测中的价值。方法将482例肺癌患者依据化疗疗效分为治疗未获益组(211例)和治疗获益组(271例),检测所有患者TR、癌胚抗原(CEA)、鳞状上皮细胞癌抗原(SCC-Ag)、细胞角蛋白19片段(CYFRA 21-1)、神经元特异性烯醇化酶(NSE)及胃泌素释放肽前体(ProGRP)水平。采用受试者工作特征(ROC)曲线评估各项指标单项及联合检测判断化疗疗效的价值。结果治疗未获益组TR、CEA及NSE水平均高于治疗获益组(P<0.05),2个组之间SCC-Ag、CYFRA21-1及ProGRP水平差异均无统计学意义(P>0.05)。治疗未获益组TR阳性率为56.40%,显著高于治疗获益组(13.16%)(P<0.05)。ROC曲线分析结果显示,TR、CEA、CYFRA 21-1、SCCAg、NSE及ProGRP单项检测判断肺癌化疗疗效的曲线下面积(AUC)分别为0.759、0.667、0.579、0.530、0.619、0.544。将各项指标进行组合,TR+CEA、TR+CEA+CYFRA21-1、TR+CEA+CYFRA21-1+NSE及TR+CEA+CYFRA 21-1+NSE+ProGRP联合检测判断肺癌化疗疗效的AUC分别为0.757、0.749、0.752和0.788。TR与CEA、NSE、SCC-Ag、CYFRA 21-1及ProGRP均无相关性(r值分别为0.05、0.02、-0.15、0.05、0.10,P>0.05)。结论TR或可作为更有效的肺癌疗效监测的生物标志物。  相似文献   
2.
3.
目的:探讨人吡咯啉-5-羧酸还原酶1(PYCR1)对胃癌细胞AGS增殖和侵袭的影响。方法:人胃癌细胞AGS转染敲减和过表达PYCR1的质粒,设置3种敲减序列,qRT-PCR和Western Blot检测PYCR1 mRNA和蛋白表达以验证敲减效率,并以敲减效率最好的进行后续实验,AGS细胞分为si-NC组、si-PYCR1组、pcDNA组、PYCR1组,采用CCK8检测各组不同时间点细胞活力,采用伤口愈合实验检测各组迁移能力,采用Transwell实验检测各组迁移和侵袭能力。结果:qRT-PCR和Western Blot检测结果发现,三种敲减序列PYCR1 mRNA和PYCR1蛋白均低于si-NC组,过表达PYCR1组PYCR1 mRNA和PYCR1蛋白高于pcDNA组,差异均有统计学意义(P<0.05)。CCK8检测各组细胞增殖活力,结果发现,si-PYCR1组48 h、72 h和96 h细胞活力显著低于si-NC组相同时间点,而PYCR1组48 h、72 h和96 h细胞活力高于pcDNA组,差异均有统计学意义(P<0.05)。伤口愈合实验检测各组细胞迁移能力,以48 h/0 h划痕宽度进行定量分析,结果发现,si-PYCR1组48 h/0 h划痕宽度高于si-NC组,PYCR1组48 h/0 h划痕宽度低于pcDNA组,差异均有统计学意义(P<0.05)。Transwell实验检测各组细胞迁移和侵袭能力,以迁移和侵袭细胞数进行定量分析,结果发现,si-PYCR1组迁移和侵袭细胞数少于si-NC组,PYCR1组迁移和侵袭细胞数多于pcDNA组,差异均有统计学意义(P<0.05)。结论:PYCR1可以促进胃癌细胞增殖、迁移及侵袭,可能是胃癌发病机制的关键分子和治疗的新靶点。  相似文献   
4.
Background:Numbers of studies have reported that the expression of aldo-keto reductase family 1 member B10 (AKR1B10) is abnormal in digestive system cancers, and could be used as a prognostic biomarker. However, the results are argued. Therefore, we conduct a meta-analysis to comprehensively evaluate the prognostic value of high AKR1B10 expression for overall survival (OS), disease specific survival (DSS), and disease-free survival/recurrence-free survival (DFS/PFS) in digestive system cancers.Methods:Hazard ratios (HRs) with its 95% confidence intervals (CIs) were calculated to assess the prognostic value of AKR1B10 by using the random effects model. The STATA version 12.0 software were used to perform all the analyses.Results:Eleven articles including 1428 patients involved in this meta-analysis. The pooled analysis suggested that high AKR1B10 expression was not associated with OS (HR: 1.18; 95% CI: 0.69–2.00) and DFS/PFS (HR: 1.08, 95% CI: 0.67–1.76) in digestive system cancers. However, Further analysis revealed that high AKR1B10 expression indicated poor OS in oral squamous cell carcinomas (OSCC) (HR: 2.92, 95% CI: 1.86–4.58) and favorable DSS in hepatocellular carcinoma (HCC) (HR: 0.71, 95% CI: 0.52–0.97).Conclusions:The prognostic value of high AKR1B10 expression varied in different types of digestive system cancers. Further studies exploring the prognostic role of AKR1B10 in digestive system cancers are needed.  相似文献   
5.
Background:Infertility affects childbearing age couples all over the world. One of the important reasons for infertility is genetic factors. Our study evaluated the association between methylenetetrahydrofolate reductase (MTHFR) and azoospermia.Methods:Multiple databases like MEDLINE, EMBASE, Cochrane library, and China journal full-text database were used to search for relevant studies, and full-text articles involved in the evaluation of MTHFR and azoospermia. The results were evaluated using STATA 12.0. Heterogeneity analysis, sensitivity analysis, and bias analysis were also performed on the data.Results:Thirteen related studies eventually met the inclusion criteria. Significant association between C677T polymorphism and azoospermia (relative risk [RR] = 0.94 [0.90, 0.99], I2 = 60.9%, P = .002), and between A1298C polymorphism and azoospermia (RR = 0.98 [0.94, 1.02], I2 = 56.3%, P = .011) was observed. Meanwhile, in subgroup analysis, Caucasians had higher risk than Mongolians in association between MTHFR and azoospermia.Conclusion:There was association between MTHFR polymorphism and azoospermia. Caucasian populations had higher risk than Mongolian populations in association between MTHFR and azoospermia.  相似文献   
6.
目的调查惠州地区人群中亚甲基四氢叶酸还原酶(MTHFR)基因C677T位点多态性的分布特征,为个体化指导育龄妇女增补叶酸及有效地降低新生儿出生缺陷风险提供科学依据。方法收集2017年6月至2019年12月在产前诊断中心门诊就诊的育龄妇女、妊娠期夫妇的外周血样本765例。采用PCR-荧光探针法检测MTHFR基因C677T位点的多态性,并与其他地区或种族人群的数据相比较。结果检出MTHFR基因C677T位点分布特征为CC野生型占54.12%(414例)、CT杂合突变型占38.43%(294例)和TT纯合突变型占7.45%(57例),三种基因型分布比值约为7:5:1。根据年龄以30岁为分界点,将基因型和等位基因分为两组,两年龄组均以野生型为主,依次为杂合突变型和纯合突变型。结论惠州地区MTHFR基因C677T位点的分布特征与其他地区存在差异,具有该地区与种族的特异性。叶酸代谢能力与个体基因型相关,该基因多态性的检测能够科学有效地指导叶酸的补充和监测。  相似文献   
7.
Statins inhibit 3-hydroxy-3-methylglutaryl-CoA reductase, the rate-limiting enzyme of the mevalonate pathway, and are widely used as an effective and safe approach handle hypercholesterolemia. The mevalonate pathway is a vital metabolic pathway that uses acetyl-CoA to generate isoprenoids and sterols that are crucial to tumor growth and progression. Multiple studies have indicated that statins improve patient prognosis in various carcinomas. Basic research on the mechanisms underlying the antitumor effects of statins is underway. The development of new anti-cancer drugs is progressing, but increasing medical costs from drug development have become a major obstacle. Readily available, inexpensive and well-tolerated drugs like statins have not yet been successfully repurposed for cancer treatment. Identifying the cancer patients that may benefit from statins is key to improved patient treatment. This review summarizes recent advances in statin research in cancer and suggests important considerations for the clinical use of statins to improve outcomes for cancer patients.  相似文献   
8.
Objective To investigate the molecular mechanisms of the adverse effects of exposure to sulfamonomethoxin(SMM) in pregnancy on the neurobehavioral development of male offspring. Methods Pregnant mice were randomly divided into four groups: control‐(normal saline), low‐ [10 mg/(kg.day)], middle‐ [50 mg/(kg.day)], and high‐dose [200 mg/(kg.day)] groups, which received SMM by gavage daily during gestational days 1‐18. We measured the levels of short‐chain fatty acids(SCFAs) in feces from dams and male pups. Furthermore, we analyzed the mR NA and protein levels of genes involved in the mammalian target of rapamycin(m TOR) pathway in the hippocampus of male pups by RT‐PCR or Western blotting. Results Fecal SCFA concentrations were significantly decreased in dams. Moreover, the production of individual fecal SCFAs was unbalanced, with a tendency for an increased level of total fecal SCFAs in male pups on postnatal day(PND) 22 and 56. Furthermore, the phosphatidylinositol 3‐kinase(PI3 k)/protein kinase B(AKT)/mTOR or mT OR/ribosomal protein S6 kinase 1(S6 K1)/4 EBP1 signaling pathway was continuously upregulated until PND 56 in male offspring. In addition, the expression of Sepiapterin Reductase(SPR), a potential target of m TOR, was inhibited. Conclusion In utero exposure to SMM, persistent upregulation of the hippocampal mTOR pathway related to dysfunction of the gut(SCFA)‐brain axis may contribute to cognitive deficits in male offspring.  相似文献   
9.
目的 调查佛山市体检人群叶酸代谢障碍关键酶基因5,10-亚甲基四氢叶酸还原酶(MTHFR)C677T位点基因多态性分布情况。方法 以佛山市182位女性和120位男性为研究对象,均为汉族人群,检测其MTHFR C677T基因位点多态性,分析性别、地域与基因多态性分布特征的关系。结果 调查的302例佛山市汉族人群MTHFR C677T位点CC、CT、TT基因型所占比例分别为62.6%、31.8%、5.6%,等位基因C、T所占比例分别为78.5%、21.5%。佛山市汉族男性与汉族女性MTHFR C677T位点多态性分布情况差异无统计学意义(P>0.05)。佛山市汉族人群与已有数据报道的武汉、西安、长治、青岛、北京、乌鲁木齐等地的汉族人群的MTHFR C677T位点基因型、等位基因的分布情况差异均有统计学意义(P<0.05)。佛山市汉族人群与回族、蒙族、维吾尔族、苗族MTHFR C677T位点基因型、等位基因的分布情况差异有统计学意义(P<0.05),与布依族差异无统计学意义(P>0.05)。结论 佛山市汉族人群MTHFR C677T位点多态性分布情况与其他地区、其他民族有显著差异,在实施个性化日常保健措施时可将遗传因素纳入考虑。  相似文献   
10.
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