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   5877篇
  免费   758篇
  国内免费   459篇
耳鼻咽喉   55篇
儿科学   117篇
妇产科学   95篇
基础医学   632篇
口腔科学   133篇
临床医学   839篇
内科学   885篇
皮肤病学   66篇
神经病学   394篇
特种医学   294篇
外国民族医学   3篇
外科学   650篇
综合类   857篇
预防医学   375篇
眼科学   157篇
药学   612篇
  9篇
中国医学   508篇
肿瘤学   413篇
  2024年   3篇
  2023年   99篇
  2022年   192篇
  2021年   312篇
  2020年   298篇
  2019年   225篇
  2018年   237篇
  2017年   240篇
  2016年   210篇
  2015年   331篇
  2014年   380篇
  2013年   293篇
  2012年   403篇
  2011年   421篇
  2010年   316篇
  2009年   235篇
  2008年   271篇
  2007年   334篇
  2006年   282篇
  2005年   278篇
  2004年   208篇
  2003年   196篇
  2002年   180篇
  2001年   145篇
  2000年   148篇
  1999年   130篇
  1998年   96篇
  1997年   100篇
  1996年   91篇
  1995年   60篇
  1994年   79篇
  1993年   32篇
  1992年   33篇
  1991年   33篇
  1990年   37篇
  1989年   29篇
  1988年   25篇
  1987年   18篇
  1986年   19篇
  1985年   16篇
  1984年   10篇
  1983年   2篇
  1982年   7篇
  1981年   4篇
  1980年   2篇
  1979年   7篇
  1978年   4篇
  1977年   13篇
  1976年   3篇
  1957年   1篇
排序方式: 共有7094条查询结果,搜索用时 125 毫秒
1.
2.
This study explores the feasibility of using diffusion kurtosis imaging (DKI) in the pelvic floor region and assesses the water diffusivity of the pubovisceral muscle. Twenty-seven healthy young nulliparous females underwent DKI at 3.0 T that included 15 gradient directions and three b values (0, 750, and 1500 s/mm2). The diffusion tensor and diffusion kurtosis metrics values of the pubovisceral muscle were measured after image processing. Two independent sample t-tests, a paired-samples t-test, and a nonparametric hypothesis test were performed as appropriate to compare the differences among different metrics. Twenty-six subjects (mean ± standard deviation age, 25 ± 2 years) were successfully analyzed by measuring the diffusion tensor and diffusion kurtosis metrics of the bilateral pubovisceral muscles. The metrics included mean kurtosis, axial kurtosis, radial kurtosis, fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. We found no statistically significant differences for these measurement values between the left and right pubovisceral muscles (p = 0.271–0.931). However, radial kurtosis was greater than axial kurtosis in both pubovisceral muscles (p < 0.001) and axial diffusivity was lower than radial diffusivity in both pubovisceral muscles (p < 0.001). We deem the application of DKI technology to the pelvic floor region to be feasible.  相似文献   
3.
Cyanidin-3-glucoside (C3G) is a well-known natural anthocyanin with antioxidant and anti-inflammatory properties. In this study, we explored the role and action mechanism of C3G in high glucose (HG)-induced damage of human nucleus pulposus cells (HNPCs). Cell viability was assessed by CCK-8 assay. TUNEL assay was performed for detecting apoptotic rate. Western blot was performed to determine the expression levels of cl-caspase-3, caspase-3, Bax, Bim, collagen II, aggrecan, MMP-3, MMP-13, and ADAMTS5. Reactive oxygen species (ROS) generation was analyzed using DCFH-DA staining. The Nrf2 was knocked down or overexpressed in HNPCs through transfection with si-Nrf2 or pcDNA3.0-Nrf2. C3G treatment (12.5, 25, and 50 μM) improved cell viability of HNPCs under HG condition. HG-induced cell apoptosis of HNPCs was attenuated by C3G with decreased apoptotic rate and relative levels of cl-caspase-3/caspase-3, Bax, and Bim. C3G treatment caused significant increase in expression levels of collagen II and aggrecan and decrease in the relative levels of MMP-3, MMP-13, and ADAMTS5. After treatment with C3G, ROS generation in HNPCs was markedly reduced. Treatment with N-acetylcysteine (NAC) reversed HG-induced cell apoptosis and extracellular matrix (ECM) degradation. C3G treatment induced the expression of Nrf2 and HO-1 in HG-induced HNPCs. Moreover, knockdown of Nrf2 reversed the inhibitory effect of C3G on ROS production. Summarily, C3G exerted a protective effect on ROS-mediated cellular damage in HNPCs under HG condition, which was attributed to the induction of the Nrf2/HO-1 signaling pathway.  相似文献   
4.
魏靖  尚海涛  程文 《现代肿瘤医学》2020,(16):2821-2826
目的:探讨原发部位分别位于左、右半结肠的结肠癌肝转移患者行超声引导下肝转移瘤射频消融术后的生存差异及预后影响因素分析。方法:回顾性分析2010年1月至2015年12月于我科行射频消融治疗的结肠癌肝转移患者100例,其中左半结肠癌62例,右半结肠癌38例,分析原发部位不同的结肠癌肝转移患者在进行超声引导下射频消融治疗后的生存情况。结果:左半结肠癌肝转移患者射频消融术后1、3、5年总体生存率及中位生存期均高于右半结肠癌肝转移患者(88.71% vs 73.68%、62.90% vs 30.02%、49.72% vs 26.33%、55个月 vs 23个月),且二者生存曲线差异具有统计学意义(P<0.05)。经Log-rank检验及COX多因素分析,左、右半结肠癌肝转移患者射频消融治疗术后的生存情况存在差异。此外,原发灶淋巴结转移情况、患者术前CA199水平及原发灶分化程度是患者射频消融治疗术后生存情况的影响因素。结论:左半结肠癌肝转移患者射频消融术后整体生存率明显高于右半结肠癌肝转移患者,左半结肠癌与右半结肠癌肝转移患者在射频消融治疗术后生存状况存在明显差异。  相似文献   
5.
长链非编码RNA(LncRNA)是一种长度超过200个核苷酸的内源RNA。大量研究表明,LncRNA可参与多种生物过程,如转录激活和干扰、细胞分化、增殖、迁移、侵袭和凋亡。近年来许多研究表明LncRNA在人类癌症中作为致癌基因或肿瘤抑制基因发挥着重要作用。大量新研究表明LncRNA肌动蛋白丝相关蛋白1反义RNA1(AFAP1-AS1)参与了多种恶性肿瘤的发生发展。已证实AFAP1-AS1的失调表达与肿瘤发生和肿瘤进展相关;AFAP1-AS1可能成为肿瘤诊断和肿瘤治疗靶点的新型潜在分子生物标志物。在本篇综述中,我们总结了现阶段关于AFAP1-AS1在人类肿瘤发生和发展过程中的生物学功能和分子机制的研究问题。  相似文献   
6.
With the application of magnetic resonance imaging (MRI)-guided photon therapy, the concept of combining real-time MRI guidance with proton therapy, namely, MRI-guided proton therapy (MRPT), has attracted widespread attention. It is expected that MRPT canmitigate the uncertaintiesduring the treatment of proton therapy to make full use of the physical advantages of protons. However, multiple electromagnetic interactions between proton therapy and MRI-guided systems may lead to mutual interference between the two systems. This article review the research progress on the MRPT system, aiming to provide certain reference for the design of MRPT system.  相似文献   
7.
MicroRNA-200a (miR-200a) is frequently downregulated in most cancer types and plays an important role in carcinogenesis and cancer progression. In this study, we determined that miR-200a was downregulated in hepatocellular carcinoma (HCC) tissues and cell lines, consistent with the results of our previous study. Because a previous study suggested that downregulation of miR-200a is correlated with HCC metastasis, we aimed to elucidate the mechanism underlying the role of miR-200a in metastasis in HCC. Here we observed that overexpression of miR-200a resulted in suppression of HCC metastatic ability, including HCC cell migration, invasion, and metastasis, in vitro and in vivo. Furthermore, bioinformatics and luciferase reporter assays indicated that GAB1 is a direct target of miR-200a. Inhibition of GAB1 resulted in substantially decreased cell invasion and migration similar to that observed with overexpression of miR-200a in HCC cell lines, whereas restoration of GAB1 partially rescued the inhibitory effects of miR-200a. Taken together, these data provide novel information for comprehending the tumor-suppressive role of miR-200a in HCC pathogenesis through inhibition of GAB1 translation.  相似文献   
8.
9.
目的了解慢性心力衰竭患者限钠饮食执行现状并分析其相关因素。方法采用中文版限钠饮食问卷对182例住院慢性心力衰竭患者进行问卷调查。结果 173例(95.05%)慢性心力衰竭患者有低盐饮食医嘱,仅23例(12.64%)得到医护人员具体盐摄入量(5~6 g/d)的指导;17例(9.83%)总是严格遵循规定的低盐饮食,89例(51.45%)多数时候严格遵循;86例(49.71%)认为遵循规定的低盐饮食非常容易及容易;48例(27.75%)认为遵循低盐饮食对管理心脏状况很有帮助。限钠饮食问卷态度维度得分为(3.90±0.52)分,主观规范得分为(4.43±0.55)分,知觉行为控制得分为(3.01±1.13)分。单因素方差分析结果显示,不同文化程度患者的限钠饮食态度维度得分比较,差异有统计学意义(P0.05),不同性别患者的知觉行为控制维度得分比较,差异有统计学意义(P0.01)。结论慢性心力衰竭患者限钠饮食执行不佳,尤其是在知觉行为控制方面。医护人员应重视对慢性心力衰竭患者执行限钠饮食阻碍因素的评估和干预,以提高患者限钠饮食依从性。  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