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   201596篇
  免费   55834篇
  国内免费   9489篇
耳鼻咽喉   2710篇
儿科学   5718篇
妇产科学   2296篇
基础医学   30567篇
口腔科学   7318篇
临床医学   29376篇
内科学   40546篇
皮肤病学   8687篇
神经病学   19489篇
特种医学   6968篇
外国民族医学   82篇
外科学   25950篇
综合类   21628篇
现状与发展   39篇
一般理论   45篇
预防医学   13078篇
眼科学   5365篇
药学   19616篇
  129篇
中国医学   9091篇
肿瘤学   18221篇
  2024年   437篇
  2023年   1992篇
  2022年   4898篇
  2021年   8188篇
  2020年   10045篇
  2019年   15021篇
  2018年   14566篇
  2017年   15440篇
  2016年   15921篇
  2015年   17914篇
  2014年   19066篇
  2013年   18847篇
  2012年   14258篇
  2011年   14846篇
  2010年   15745篇
  2009年   10813篇
  2008年   9128篇
  2007年   7655篇
  2006年   7653篇
  2005年   6946篇
  2004年   5010篇
  2003年   4705篇
  2002年   4091篇
  2001年   3669篇
  2000年   3469篇
  1999年   3244篇
  1998年   1867篇
  1997年   1791篇
  1996年   1394篇
  1995年   1356篇
  1994年   1124篇
  1993年   699篇
  1992年   860篇
  1991年   722篇
  1990年   651篇
  1989年   557篇
  1988年   521篇
  1987年   409篇
  1986年   335篇
  1985年   283篇
  1984年   165篇
  1983年   117篇
  1982年   63篇
  1981年   66篇
  1980年   39篇
  1979年   82篇
  1978年   33篇
  1974年   29篇
  1973年   22篇
  1968年   18篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
11.
目的  探讨Hsa-miR-4282在肝癌细胞系SMMC-7721中的表达及其对细胞生长的影响。方法 采用实时荧光定量PCR法检测Hsa-miR-4282在人正常肝上皮细胞系HL-7702和人肝癌细胞系MHCC97-H、SMMC-7721,以及 20例肝癌组织及其相应癌旁组织中的表达。采用瞬时转染法将Hsa-miR-4282 mimics(上调组)和Hsa-miR-4282 inhibitor(下调组)分别转染肝癌SMMC-7721细胞,上调组和下调组分别设置相应阴性对照组。转染后采用MTT法检测细胞增殖能力,平板克隆形成实验检测细胞克隆形成能力,流式细胞仪检测细胞凋亡能力。结果 Hsa-miR-4282在肝癌组织、肝癌细胞MHCC97-H及肝癌细胞SMMC-7721中的表达均低于癌旁组织及正常肝细胞HL-7702(P<0.05)。MTT实验结果显示,Hsa-miR-4282上调后肝癌SMMC-7721细胞的OD值低于其阴性对照组,而下调后OD值高于其阴性对照组 (P<0.05)。平板克隆形成实验显示,下调组的细胞克隆数高于其阴性对照组[(240±7) 个 vs (191±10) 个,P=0.005)],而上调组细胞克隆数低于基阴性对照组[(146±10) 个 vs (193±12) 个,P=0.013)]。流式细胞仪检测结果显示,Hsa-miR-4282上调组细胞凋亡率较其阴性对照组升高[(23.89±1.89)% vs(16.6±1.14)%,P=0.009)],下调组细胞凋亡率较期阴性对照组降低[(14.98±0.46)% vs (17.79±0.73)%,P=0.010]。结论 Hsa-miR-4282上调可抑制肝癌SMMC-7721细胞增殖,促进细胞凋亡,可能与肝癌的发病机制有关。  相似文献   
12.
Metformin, a drug for type 2 diabetes mellitus, has shown therapeutic effects for various cancers. However, it had no beneficial effects on the survival rate of human malignant mesothelioma (HMM) patients. The present study was performed to elucidate the underlying mechanism of metformin resistance in HMM cells. Glucose‐starved HMM cells had enhanced resistance to metformin, demonstrated by decreased apoptosis and autophagy and increased cell survival. These cells showed abnormalities in mitochondria, such as decreased ATP synthesis, morphological elongation, altered mitochondrial permeability transition pore and hyperpolarization of mitochondrial membrane potential (MMP). Intriguingly, Mdr1 was significantly upregulated in mitochondria but not in cell membrane. The upregulated mitochondrial Mdr1 was reversed by treatment with carbonyl cyanide m‐chlorophenyl hydrazone, an MMP depolarization inducer. Furthermore, apoptosis and autophagy were increased in multidrug resistance protein 1 knockout HMM cells cultured under glucose starvation with metformin treatment. The data suggest that mitochondrial Mdr1 plays a critical role in the chemoresistance to metformin in HMM cells, which could be a potential target for improving its therapeutic efficacy.  相似文献   
13.
目的:探讨血化瘀方联合针灸治疗对脑梗后遗症患者脑血管血液流变动力学及神经功能的影响。方法:选取2016年1月至2017年1月沈阳市第二中医医院收治脑梗后遗症患者120例作为研究对象,对照组61例患者接受针灸治疗;观察组59例患者接受活血化瘀方联合针灸治疗。2组连续治疗30 d。比较2组患者脑血流流变学指标、神经功能评分、中医证候积分、临床疗效。结果:治疗前2组患者脑部平均血流速度、左侧椎动脉血流量、右侧椎动脉血流量、基底动脉血流量比较,差异无统计学意义(P 0. 05)。治疗后观察组患者脑部平均血流速度、左侧椎动脉血流量、右侧椎动脉血流量、基底动脉血流量大于对照组(P 0. 05)。治疗前2组患者NIHSS评分、MMSE评分比较,差异无统计学意义(P 0. 05)。治疗后观察组患者NIHSS评分显著低于对照组,MMSE评分高于对照组(P 0. 05)。治疗前2组患者头晕目眩、语言謇涩、半身不遂、患侧麻木、舌苔白腻证候评分比较,差异无统计学意义(P 0. 05)。治疗后研究患者头晕目眩、语言謇涩、半身不遂、患侧麻木、舌苔白腻证候评分显著低于对照组(P 0. 05)。2组患者临床疗效比较,差异有统计学意义(Z=-5. 626,P=0. 000)。结论:活血化瘀方联合针灸能改善脑梗后遗症患者脑血管血液流变动力学指标,保护神经功能。  相似文献   
14.
15.
We report a case of benign lymphoplasmacytic plaque (LPP) in a child. These asymptomatic erythematous papulonodular lesions are an emerging clinicopathological entity. Herein, we describe a previously unreported site for LPP lesions, namely, the volar wrist and the distal ipsilateral palm.  相似文献   
16.
17.
18.
It is well recognized that the world population is ageing rapidly. Therefore, it is important to understand ageing processes at the cellular and molecular levels to predict the onset of age‐related diseases and prevent them. Recent research has focused on the identification of ageing biomarkers, including those associated with the properties of the Golgi apparatus. In this context, Golgi‐mediated glycosylation of proteins has been well characterized. Additionally, other studies show that the secretion of many compounds, including pro‐inflammatory cytokines and extracellular matrix–degrading enzymes, is modified during ageing, resulting in physical and functional skin degradation. Since the Golgi apparatus is a central organelle of the secretory pathway, we investigated its structural organization in senescent primary human dermal fibroblasts using confocal and electron microscopy. In addition, we monitored the expression of Golgi‐related genes in the same cells. Our data showed a marked alteration in the Golgi morphology during replicative senescence. In contrast to its small and compact structure in non‐senescent cells, the Golgi apparatus exhibited a large and expanded morphology in senescent fibroblasts. Our data also demonstrated that the expression of many genes related to Golgi structural integrity and function was significantly modified in senescent cells, suggesting a relationship between Golgi apparatus function and ageing.  相似文献   
19.
Radiodermatitis is one of the commonest side effects of radiotherapy. They are usually assessed by semi‐quantitative clinical scores, which are not validated and may be subject to inter‐observer variability. A few previous studies suggested that high‐frequency ultrasonography (HF‐USG) is useful in the assessment of the acute phase of radiation dermatitis in breast cancer patients. (a) To monitor skin changes by HF‐USG during the course of radiotherapy due to head and neck cancers, and (b) to determine whether there is any connection between skin sonograms and the skin scoring criteria. This prospective, observational study includes patients diagnosed with head and neck cancers, treated with radiotherapy or concomitant chemoradiation. The final analysis includes six patients. In every patient, the HF‐USG as well as dermatological assessment (target lesion score—TLS and CACE v. 4.0) were performed 4×: before, in the middle, day after, and 3 months after radiotherapy. There were significant differences between non‐irradiated skin thickness and thickness of skin with clinically obvious radiodermatitis (TLS grade 1‐4; P < .0001), as well as between irradiated, unchanged skin thickness (TLS grade 0) and thickness of skin with clinically obvious radiodermatitis (TLS grade 1‐4; P = .0002). There was no significant difference between non‐irradiated and irradiated, unchanged skin thickness (TLS grade 0; P = .9318). In four patients, we demonstrated subepidermal low echogenic band (SLEB). HF‐USG can be useful tool to noninvasive and objective assessment of skin changes during radiotherapy.  相似文献   
20.
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