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   22298篇
  免费   2063篇
  国内免费   1197篇
耳鼻咽喉   8篇
儿科学   156篇
妇产科学   16篇
基础医学   1671篇
口腔科学   33篇
临床医学   1897篇
内科学   4448篇
皮肤病学   25篇
神经病学   515篇
特种医学   472篇
外国民族医学   41篇
外科学   2926篇
综合类   4703篇
现状与发展   1篇
预防医学   617篇
眼科学   11篇
药学   1809篇
  26篇
中国医学   1252篇
肿瘤学   4931篇
  2024年   49篇
  2023年   345篇
  2022年   617篇
  2021年   916篇
  2020年   803篇
  2019年   665篇
  2018年   597篇
  2017年   763篇
  2016年   907篇
  2015年   899篇
  2014年   1354篇
  2013年   1546篇
  2012年   1282篇
  2011年   1365篇
  2010年   1047篇
  2009年   973篇
  2008年   1047篇
  2007年   1245篇
  2006年   976篇
  2005年   964篇
  2004年   782篇
  2003年   642篇
  2002年   617篇
  2001年   632篇
  2000年   592篇
  1999年   464篇
  1998年   426篇
  1997年   353篇
  1996年   343篇
  1995年   362篇
  1994年   326篇
  1993年   242篇
  1992年   202篇
  1991年   207篇
  1990年   177篇
  1989年   149篇
  1988年   143篇
  1987年   98篇
  1986年   53篇
  1985年   58篇
  1984年   67篇
  1983年   42篇
  1982年   43篇
  1981年   32篇
  1980年   34篇
  1979年   27篇
  1978年   16篇
  1977年   20篇
  1976年   17篇
  1975年   10篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
991.
目的探讨胃癌组织中沉默信息调节因子1(SIRT-1)和血管内皮生长因子(VEGF)的表达及临床意义。方法选取2016年6月至2018年6月本院胃癌患者120例,均接受胃癌手术切除术。采用免疫组化检测胃癌组织及其癌旁正常组织中SIRT-1、VEGF的表达。结果胃癌组织SIRT-1、VEGF表达阳性率明显高于癌旁正常组织,差异有统计学意义(P<0.05);胃癌组织SIRT-1、VEGF的表达与TNM分期、浸润深度、浆膜受侵、淋巴结转移有关(P<0.05),与性别、年龄、肿瘤位置、分化程度、肿瘤直径无关(P>0.05);胃癌组织SIRT-1与VEGF表达呈正相关(P<0.05)。结论胃癌组织中SIRT-1、VEGF呈高表达状态,且与胃癌的发生发展有关,可能共同促进了胃癌的生长、侵袭、转移等生物学行为。  相似文献   
992.
目的探究转化生长因子-β1(TGF-β1)对胃癌细胞增殖、凋亡及miR-302a和AKT通路的影响.方法在含有TGF-β1(0、1、5、10 ng/ml)的培养基培养胃癌细胞系BGC-823,MTT法检测细胞增殖情况;平板克隆形成实验检测细胞克隆形成数量;Hoechst33258染色观察细胞形态;流式细胞术检测细胞凋亡以及周期阻滞情况;实时荧光定量PCR(qRT-PCR)检测细胞miR-302a表达;蛋白印迹(WB)法检测p-PI3K、AKT、p-AKT蛋白表达情况.结果与Control组相比,TGF-β1处理组细胞增殖抑制率、细胞凋亡率升高,细胞克隆数量降低,且随着TGF-β1浓度的增加,细胞增殖抑制率、细胞凋亡率逐渐升高,细胞克隆数量逐渐降低(P<0.05).与Control组相比,TGF-β1处理组G1期细胞比例显著增加,G2期细胞比例显著降低,且随着TGF-β1浓度的增加,G1期细胞比例逐渐增加,G2期细胞比例逐渐降低(P<0.05).与Control组相比,TGF-β1处理组miR-302a表达升高,p-PI3K、p-AKT蛋白表达水平均显著降低,且随着TGF-β1浓度的增加,miR-302a表达逐渐升高,p-PI3K、p-AKT蛋白表达逐渐降低(P<0.05).结论TGF-β1可能通过上调miR-302a表达、抑制AKT通路,使细胞G1期阻滞,从而抑制胃癌细胞增殖,促进其凋亡.  相似文献   
993.

Background

Ethno-botanical information shows that Eremomastax speciosa is used in the traditional management of various stomach complaints including gastro-duodenal ulcers.

Materials and Methods

In this study, we tested the cytoprotective potential of the whole plant methanol extract (100–200 mg/kg, p.o), against HCl/ethanol, absolute ethanol, cold/restraint stress rats, and pylorus legated rats pre-treated with indomethacin. The effects of the extract on gastric lesion inhibition, the volume of gastric juice, gastric pH, gastric acid output, mucus production and gastric peptic activity were recorded. Oxidative stress parameters were measured in blood and gastric tissue samples obtained from the animals in all the models tested.

Results

The extract significantly (p<0.05), reduced the formation of cold/restraint ulcers by (31–60%, inhibition), completely inhibited (100%) the formation of lesions induced by HCl/ethanol at the highest dose, but was less effective against absolute ethanol (22–46% inhibition). The extract (200 mg/kg), significantly reduced lesion formation (P<0.01), gastric acidity (P<0.01), and volume of gastric secretions (P<0.05), in the indomethacin/pylorus ligation model, and did not affect the activity of pepsin in gastric juice. Blood concentrations of antioxidant enzymes (catalase, SOD and GSH), increased significantly and MDA concentrations decreased in all models tested.

Conclusion

Cytoprotection by E. speciosa methanol extract was attributed to its ability to reduce acid secretion, and to enhance mucosal defence and in vivo antioxidant status.  相似文献   
994.

Background

Allicin is the main active constituent of Allium sativum L., which is characterized by broad antibacterial spectrum (MarkosN et al., 2008; Chen et al., 2008); it also has apparent inhibitory effects on a variety of tumors. The Objective of the paper is to study the inhibitory effect of allicin on human gastric cancer cell line SGC-7901.

Materials and Methods

MTT assay and flow cytometry technique were applied to determine the inhibition rate of allicin on human gastric cancer cell line SGC-7901. The results shows that different concentrations of allicin apparently inhibited the gastric cancer SGC7901 cells, cell growth inhibition rates in the experimental groups showed an upward trend with increased allicin concentration, which were concentration-dependent.

Results

Flow cytometry results found that the cell cycle was arrested in the G2/M phase. Allicin has an apparent inhibitory effect on proliferation of gastric cancer cells, and can induce their apoptosis.

Conclusion

Compared with other chemotherapeutic drugs, allicin''s anti-tumor effect is better; and toxic and side effects are relatively small.  相似文献   
995.

Background

Gastric cancer (GC) is a progressive process initiated by Helicobacter pylori-induced inflammation. Initial recognition of H. pylori involves Toll-like receptors (TLRs), central molecules in the host inflammatory response. Here, we investigated the association between novel polymorphisms in genes involved in the TLR signalling pathway, including TLR2, TLR4, LBP, MD-2, CD14 and TIRAP, and risk of H. pylori infection and related GC.

Methods

A case-control study comprising 310 ethnic Chinese individuals (87 non-cardia GC cases and 223 controls with functional dyspepsia) was conducted. Twenty-five polymorphisms were detected by MALDI-TOF mass spectrometry, PCR, PCR–RFLP and real-time PCR.

Results

Seven polymorphisms showed significant associations with GC (TLR4 rs11536889, TLR4 rs10759931, TLR4 rs1927911, TLR4 rs10116253, TLR4 rs10759932, TLR4 rs2149356 and CD14 −260 C/T). In multivariate analyses, TLR4 rs11536889 remained a risk factor for GC (OR: 3.58, 95% CI: 1.20–10.65). TLR4 rs10759932 decreased the risk of H. pylori infection (OR: 0.59, 95% CI: 0.41–0.86). Statistical analyses assessing the joint effect of H. pylori infection and the selected polymorphisms revealed strong associations with GC (TLR2, TLR4, MD-2, LBP and TIRAP polymorphisms).

Conclusions

Novel polymorphisms in TLR2, TLR4, MD-2, LBP, CD14 and TIRAP, genes encoding important molecules of the TLR signalling pathway, showed clear associations with H. pylori-related GC in Chinese.  相似文献   
996.
Gender differences in terms of mortality among many solid organ malignancies have been proved by epidemiological data. Estrogen has been suspected to cast a protective effect against cancer because of the lower mortality of gastric cancer in females and the benefits of hormone replacement therapy (HRT) in gastric cancer. Hence, it suggests that 17β-estradiol (E2) may affect the behavior of cancer cells. One of the key features of cancer-related mortality is metastasis. Accumulating evidences suggest that human bone marrow mesenchymal stem cells (HBMMSCs) and its secreted CCL-5 have a role in enhancing the metastatic potential of breast cancer cells. However, it is not clear whether E2 would affect HBMMSCs-induced mobility in gastric cancer cells. In this report, we show that CCL-5 secreted by HBMMSCs enhanced mobility in human AGS gastric cancer cells via activation of Src/Cas/Paxillin signaling pathway. Treatment with specific neutralizing antibody of CCL-5 significantly inhibited HBMMSCs-enhanced mobility in human AGS gastric cancer cells. We further observe that 17β-estradiol suppressed HBMMSCs-enhanced mobility by down-regulating CCL5-Src/Cas/paxillin signaling pathway in AGS cells. Collectively, these results suggest that 17β-estradiol treatment significantly inhibits HBMMSCS-induced mobility in human AGS gastric cancer cells.  相似文献   
997.
目的:应用变性高效液相色谱技术(denaturing—performanceliquidchromatography,DHPLC)高通量的实验平台,探讨晚期胃癌患者细胞色素P450代谢酶CYP3A4基因的多态性与患者接受多线化疗、化疗周期数及不良反应的相关性。方法:福建省肿瘤医院住院的接受含紫杉醇和/或奥沙利铂联合姑息化疗晚期胃癌患者外周血53份,进行全血DNA分离、提取,经PCR,DHPLC分析筛查以及DNA测序鉴定基因型,观察并评价患者接受多线化疗、化疗周期数及不良反应与CYP3A4多态性的相关性。结果:53例进展期胃癌患者CYP3A4经DHPLC筛查,单峰者f野生型)32例,双峰者(突变型)21例。测序结果显示双峰者CYP3A4第10号外显子上27位c的缺失突变。单峰组接受一线治疗15例,二线治疗10例,二线以上治疗8例,其中3例为三线以上治疗;平均化疗周期数为8.2周期,中位总生存时问为13.0个月(95%CI:7.092~18.908个月)。双峰组接受一线治疗10例,二线治疗8例,二线以上治疗3例,平均化疗8.7周期,中位总生存时间为14.0个月(95%CI:7.555~20.445个月)。两组中位总生存时间比较差异无统计学意义(P=0.326)。野生型组较突变型组不良反应发生率低,在3~4级毒副作用方面较为明显,结论:CYP3A4突变型者第10号外显子上第27位C缺失;该基因多态性与化疗不良反应相关,尚不能作为疗效的预测指标。  相似文献   
998.
目的 检测中国人群胃癌组织中PIK3 CA基因突变频率及热点突变模式,探讨PIK3 CA基因突变的临床意义.方法 应用荧光PCR法筛查胃癌PIK3 CA基因突变阳性病例,Sanger DNA测序法检测PIK3CA基因热点突变模式;统计分析PIK3 CA基因突变与胃癌临床病理特征之间的关系.结果 400例肿瘤标本中检测出PIK3 CA基因突变率为7.5% (30/400),突变位点主要集中在第9外显子(E542K,E545K)和第20外显子(H1047R,H1047L);且PIK3 CA基因突变与肿瘤预后相关(P<0.05),而与肿瘤大小、组织学分级、淋巴结状态、患者年龄等因素无关.结论 中国人群胃癌组织中PIK3CA基因突变具独特的突变频率与突变模式;PIK3 CA基因突变对于胃癌预后判断及基因靶向治疗具潜在临床价值.  相似文献   
999.
目前,腹腔镜技术因其优点越来越受到临床医师的重视,具有创伤小、恢复快、术后生活质量高等优点,其应用范围随也逐渐扩大。经多年的临床实践证明其在胃癌患者中的应用效果良好,本文就腹腔镜技术在胃癌的诊断、应用及研究进展等作一综述。  相似文献   
1000.
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