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   451386篇
  免费   31974篇
  国内免费   7083篇
耳鼻咽喉   6064篇
儿科学   9123篇
妇产科学   10837篇
基础医学   62096篇
口腔科学   13064篇
临床医学   38114篇
内科学   88404篇
皮肤病学   9885篇
神经病学   30710篇
特种医学   17698篇
外国民族医学   103篇
外科学   68033篇
综合类   21746篇
现状与发展   29篇
一般理论   71篇
预防医学   22324篇
眼科学   11650篇
药学   39201篇
  66篇
中国医学   6054篇
肿瘤学   35171篇
  2021年   5327篇
  2020年   4056篇
  2019年   4924篇
  2018年   6886篇
  2017年   5696篇
  2016年   5933篇
  2015年   7651篇
  2014年   10189篇
  2013年   11821篇
  2012年   16514篇
  2011年   17095篇
  2010年   10754篇
  2009年   9747篇
  2008年   14302篇
  2007年   14866篇
  2006年   14572篇
  2005年   13099篇
  2004年   11665篇
  2003年   11387篇
  2002年   10566篇
  2001年   29773篇
  2000年   29993篇
  1999年   24734篇
  1998年   5741篇
  1997年   4763篇
  1996年   4244篇
  1995年   3999篇
  1994年   3606篇
  1993年   3168篇
  1992年   16360篇
  1991年   15112篇
  1990年   14381篇
  1989年   14155篇
  1988年   12715篇
  1987年   12198篇
  1986年   11210篇
  1985年   10391篇
  1984年   6949篇
  1983年   5625篇
  1982年   2742篇
  1979年   5489篇
  1978年   3350篇
  1977年   2965篇
  1975年   2643篇
  1974年   3066篇
  1973年   2873篇
  1972年   2832篇
  1971年   2773篇
  1970年   2511篇
  1969年   2544篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
目的 观察具有益气化痰活血作用的冠心康对人单核/巨噬细胞株THP-1细胞PERK-eIF2α信号通路及相关活化转录因子(ATF)和C/EBP同源转录因子(CHOP)的影响,探究冠心康对胆固醇在巨噬细胞内质网中的代谢稳态调节及作为“脂毒”流出后异常沉积的相关作用。方法 采用100 ng·mL-1 PMA及80 μg·mL-1氧化低密度脂蛋白诱导THP-1细胞株,构建巨噬细胞模型,并随机分为模型组、冠心康组、辛伐他汀组、正常组。分别采用10%小牛血清及含药血清干预模型细胞72 h后收集细胞。HE染色观察巨噬细胞病理形态变化,同时进行胆固醇及脂滴含量测定。分别采用Real-time PCR及Western blot法检测各组细胞PERK、eIF2α、ATF、CHOP mRNA及蛋白的表达。结果 HE染色观察到模型组细胞内呈现较多红色脂滴,经胆固醇含量测定,明显高于正常组,脂滴含量测定与前者一致(P<0.01)。模型组细胞ATF、CHOP基因表达水平均显著升高(P<0.01)。与模型组比较,冠心康组和辛伐他汀组细胞ATF、CHOP基因表达水平均显著降低(P<0.01)。PERK磷酸化以及CHOP蛋白表达水平在冠心康和辛伐他汀干预组表现为显著下调,与模型组比较,差异具有统计学意义(P<0.05)。结论 冠心康可能通过调控PERK-eIF2α-CHOP通路相关基因及蛋白,减少泡沫细胞形成,从而减轻内质网应激,维持细胞内胆固醇稳态,减少细胞内胆固醇沉积。  相似文献   
3.
Whether the underlying mutations are homozygous, heterozygous, or co-inherited with other hemoglobinopathies, sickle cell disease is known to afflict the kidneys, leading to the clinical entity known as sickle cell nephropathy (SCN). Although common, SCN remains diagnostically elusive. Conventional studies performed in the context of renal disorders often fail to detect early stage SCN. This makes the quest for early diagnosis and treatment more challenging, and it increases the burden of chronic kidney disease-related morbidity among patients. Novel diagnostic tools have been employed to overcome this limitation. In this study, we discuss various biomarkers of SCN, including those employed in clinical practice and others recently identified in experimental settings, such as markers of vascular injury, endothelial dysfunction, tubulo-glomerular damage, and oxidative stress. These include kidney injury molecule-1, monocyte chemoattractant protein-1, N-acetyl-B-D-glucosaminidase, ceruloplasmin, orosomucoid, nephrin, and cation channels, among others. Furthermore, we explore the potential of novel biomarkers for refining diagnostic and therapeutic approaches and describe some obstacles that still need to be overcome. We highlight the importance of a collaborative approach to standardize the use of promising new biomarkers. Finally, we outline the limitations of conventional markers of renal damage as extensions of the pathogenic process occurring at the level of the organ and its functional subunits, with a discussion of the expected pattern of clinical and biochemical progression among patients with SCN.  相似文献   
4.
摘要:目的:探讨超声造影(CEUS)定量分析对常规超声联合CEUS定性诊断误诊为恶性的甲状腺结节与甲状腺乳头状癌的鉴别诊断价值。方法:选取2018年7月至2021年11月在我院超声科行甲状腺常规超声及CEUS检查,术前联合超声诊断为恶性(C-TIRADS≥4b 或 CEUS 表现为低增强和快速消退任一征像)而病理为良性的35位患者共35个结节为研究组;选择同期联合超声诊断与病理一致的甲状腺乳头状癌患者47例做为对照组。分析常规超声及CEUS特征,并将结节整体、中央部、边缘部及邻近正常甲状腺实质作为感兴趣区分别绘制时间-强度曲线(TIC)进行定量分析,比较两组结节各定量参数之间的差异。结果:研究组整体相对上升时间(△RT)以0.45为截断值,诊断恶性结节的敏感度为97.9%,特异度为85.7%,受试者工作(ROC)曲线下面积为0.96;研究组中央区△RT以0.55为截断值,诊断恶性结节的敏感度为95.7%,特异度为82.9%,ROC曲线下面积为0.87;研究组边缘区△RT以0.25为截断值,诊断恶性结节的敏感度为89.4%,特异度为77.1%,ROC曲线下面积为0.89。结论:CEUS定量分析在常规超声联合CEUS定性误诊甲状腺结节的诊断中具有一定的鉴别诊断价值。  相似文献   
5.
6.
The use of radiation for primary liver cancers has historically been limited because of the risk of radiation-induced liver disease. Treatment fields have become more conformal because of several technical advances, and this has allowed for dose escalation. Stereotactic body radiation therapy (SBRT), also known as stereotactic ablative radiotherapy, is now able to safely treat liver tumors to ablative doses while sparing functional liver parenchyma by using highly conformal therapy. Several retrospective and small prospective studies have examined the use of SBRT for liver cancers; however, there is a lack of well-powered randomized studies to definitively guide management in these settings. Recent advances in systemic therapy for primary liver cancers have improved outcomes; however, the optimal selection criteria for SBRT as a local therapy remain unclear among other liver-directed options such as radiofrequency ablation, transarterial chemoembolization, and radioembolization.  相似文献   
7.
8.
Peng  L. Q.  Wu  X. X.  Chen  G.  Cai  H. Z.  Tang  Y. P.  Chen  Q. Y.  Chen  X. Y. 《Bulletin of experimental biology and medicine》2022,173(3):335-340
Bulletin of Experimental Biology and Medicine - This study aimed to explore the effects of Wenyang Zhenshuai granules (WZG) on the morphology of cardiomyocytes, cell viability, and the expression...  相似文献   
9.
10.
Post-induction hypotension is common and associated with postoperative complications. We hypothesised that pneumatic leg compression reduces post-induction hypotension in elderly patients undergoing robot-assisted laparoscopic prostatectomy. In this double-blind randomised study, patients were allocated randomly to the pneumatic leg compression group (n = 50) or control (n = 50). In the intervention group, pneumatic leg compression was initiated before induction of anaesthesia. In the control group, pneumatic leg compression was initiated 20 min after anaesthesia induction. The primary outcome was the incidence of post-induction hypotension in these groups. Post-induction hypotension was defined as systolic blood pressure < 90 mmHg during the first 20 min after induction. Haemodynamic variables and area under the curve of post-induction systolic blood pressure over time were assessed. Complications associated with pneumatic leg compression were recorded, including: peripheral neuropathy; compartment syndrome; extensive bullae beneath the leg sleeves; and pulmonary thromboembolism. The incidence of post-induction hypotension decreased in the pneumatic leg compression group compared with that in the control group; 5 (10%) vs. 29 (58%), respectively, p < 0.001. In the pneumatic leg compression group, the lowest systolic, diastolic and mean blood pressures 20 min after induction of anaesthesia were significantly greater than the control group. Pneumatic leg compression resulted in an increased area under the curve of systolic blood pressure in the first 20 min after induction, p = 0.001. There were no pneumatic leg compression-related complications. Pneumatic leg compression reduced post-induction hypotension in elderly patients undergoing robot-assisted laparoscopic prostatectomy, suggesting that it is an effective and safe intervention to prevent post-induction hypotension among elderly patients undergoing general anaesthesia.  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