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   190645篇
  免费   18787篇
  国内免费   7196篇
耳鼻咽喉   1189篇
儿科学   4491篇
妇产科学   2679篇
基础医学   36443篇
口腔科学   3714篇
临床医学   11976篇
内科学   32175篇
皮肤病学   3236篇
神经病学   15722篇
特种医学   3681篇
外国民族医学   57篇
外科学   13973篇
综合类   23707篇
现状与发展   30篇
预防医学   8351篇
眼科学   2239篇
药学   25623篇
  20篇
中国医学   6703篇
肿瘤学   20619篇
  2024年   155篇
  2023年   2860篇
  2022年   3726篇
  2021年   7155篇
  2020年   6693篇
  2019年   7722篇
  2018年   7318篇
  2017年   7215篇
  2016年   7057篇
  2015年   8460篇
  2014年   11845篇
  2013年   13231篇
  2012年   12170篇
  2011年   14421篇
  2010年   12260篇
  2009年   11630篇
  2008年   11035篇
  2007年   9835篇
  2006年   8904篇
  2005年   7587篇
  2004年   6643篇
  2003年   5643篇
  2002年   4362篇
  2001年   3716篇
  2000年   3051篇
  1999年   2636篇
  1998年   2011篇
  1997年   1897篇
  1996年   1568篇
  1995年   1581篇
  1994年   1380篇
  1993年   1163篇
  1992年   965篇
  1991年   867篇
  1990年   714篇
  1989年   599篇
  1988年   513篇
  1987年   415篇
  1986年   422篇
  1985年   796篇
  1984年   820篇
  1983年   574篇
  1982年   644篇
  1981年   508篇
  1980年   418篇
  1979年   365篇
  1978年   280篇
  1977年   221篇
  1976年   206篇
  1975年   142篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
《Drug discovery today》2022,27(1):223-233
Approaches based on animal and two-dimensional (2D) cell culture models cannot ensure reliable results in modeling novel pathogens or in drug testing in the short term; therefore, there is rising interest in platforms such as organoids. To develop a toolbox that can be used successfully to overcome current issues in modeling various infections, it is essential to provide a framework of recent achievements in applying organoids. Organoids have been used to study viruses, bacteria, and protists that cause, for example, respiratory, gastrointestinal, and liver diseases. Their future as models of infection will be associated with improvements in system complexity, including abilities to model tissue structure, a dynamic microenvironment, and coinfection.Teaser.Organoids are a flexible tool for modelling viral, bacterial and protist infections. They can provide fast and reliable information on the biology of pathogens and in drug screening, and thus have become essential in combatting emerging infectious diseases.  相似文献   
63.
Ochratoxin A (OTA) is a mycotoxin that mainly causes nephrotoxicity. The single nephrotoxicity of OTA exposure on glomeruli or renal tubule had been well documented, however, the comparison toxicity between it is still unclear. Here, C57BL/6 mice and two types of nephrocyte were treated with concentration-gradient OTA to explore its differentiation nephrotoxicity. Results showed that OTA induced nephrotoxicity in vivo and in vitro, manifested as the deteriorative kidney function in mice and the cut-down cell viability in nephrocyte. Besides, results of murine kidney pathological section and IC50 of two types nephrocyte indicated that OTA-induced toxicity in renal tubule was higher than its in glomeruli. In addition, OTA exposure induced autophagy signaling differentiation expression. It revealed that autophagy was implicated in OTA-induced differential nephrotoxicity in glomeruli and renal tubule. Altogether, we proved that OTA induces a differentiation nephrotoxicity in glomeruli and renal tubule, and it is related to autophagy differential regulation.  相似文献   
64.
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   
65.
66.
IntroductionDating the exact or estimated time of trauma is an important issue facing forensic medicine. Several clinical and radiological methods were used to achieve this purpose. In the recent study, we aimed to track the changes in the signal intensity of the extra-axial brain hematoma using magnetic resonance imaging (MRI) conventional sequences as well as diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC).Materials and methodsConsidering inclusion and exclusion criteria, all patients with blunt head trauma were involved. After proper management., stabilization, and resuscitation, the participants were assessed using conventional sequences of MRI and DWI twenty-four hours, forty-eight hours, and three weeks after the injury. Temporal changes of signal intensity were compared by Wilcoxon ranged test.ResultsSixteen patients sustaining blunt head trauma were included in this study. The study showed that during the time, diffusion restriction could be seen in an extraaxial hematoma. At the first 24 hours, the signal of hematoma was void in 87.5% of DWI and 100% of ADC. On the second day, they were hypo-signal in 75% of DWI and 100% 0f ADCs, and after three weeks, 100% of cases were hyper-signal in DWI and hypo-signal ADCs.ConclusionThis preliminary study has shown that the DWI can be used to detect and track the extra-axial hematoma. The signal intensity was void during the first twentyfour hours, although it became hypo-signal after 48 hours. Of note, the diffusion restriction is noted after three weeks.  相似文献   
67.
68.
目的 探讨滋肾育胎丸加减方预防抗磷脂抗体(ACA)阳性者不良妊娠结局的效果及机制研究。方法 选取2016年2月至2019年2月我院收治的89例ACA阳性,先兆性流产或有习惯性流产(RSA)史患者,将采用西医治疗的40例作为对照组,将采用西医联合滋肾育胎丸加减方治疗的49例作为观察组,比较两组中医证候疗效、中医证候积分、ACA-IgA、ACA-IgM、ACA-IgG、凝血指标[血小板聚集功能(PAF)、活化蛋白C(PC)、抗凝血酶(AT)、纤溶酶原激活抑制物-1(PAI-1)]、Th1/Th2细胞因子[干扰素γ(IFN-γ)、白介素-2(IL-2)、白介素-4(IL-4)、白介素-10(IL-10)]、妊娠结局、安全性。结果 治疗2周后检测ACA,观察组2例未降低,对照组11例未降低,观察组未降低患者占比低于对照组(P<0.05);观察组总有效率100.00%高于对照组85.00%(P<0.05);观察组治疗4周、7周后中医证候积分低于对照组(P<0.05);观察组治疗4周、7周后ACA-IgA、ACA-IgM、ACA-IgG低于对照组(P<0.05);观察组治疗4周、7周后PAF、PAI-1低于对照组,PC、AT高于对照组(P<0.05);观察组治疗4周、7周后IFN-γ、IL-2低于对照组,IL-4、IL-10高于对照组(P<0.05);观察组活产率95.92%高于对照组80.00%(P<0.05);组间不良反应总发生率比较,差异无统计学意义(P>0.05)。结论 动态监测ACA对滋肾育胎丸加减方精准应用具有指导意义,指导滋肾育胎丸加减方通过调理脏腑、气血、经络功能,改善先兆性流产或有RSA史患者临床症状及凝血因子指标,降低ACA水平,并可改善患者免疫耐受功能,提高胎儿活产率,且安全性高。  相似文献   
69.
ObjectiveTo investigate the blood levels of adipokines in obese patients with endometrial cancer who have and have not undergone omentectomy.MethodsBetween September 2017 and September 2019, the study recruited 54 patients with endometrial cancer. Measurements were taken of blood levels of human leptin, perilipin-1, adiponectin, adipolin, resistin, visfatin, and estrone preoperatively and postoperatively before adjuvant therapy or at the end of one month. The serum samples were separated by centrifugation for 10 mins at 3,000 revolutions/min, then stored at ?80 °C until assay.ResultsIn this prospective study, a total of 54 endometrial cancer patients were analyzed in two separate groups according to the omentectomy status. Comprehensive staging surgery with omentectomy and without omentectomy was performed in 26 patients and 28 patients, respectively. The age, body mass index, body fat index, waist circumference, and skin thickness values of the patients with and without omentectomy were found to be similar. No statistically significant difference was determined between the patients with and without omentectomy in respect of the blood level of the adipokines measured preoperatively. A strong statistically significant correlation was determined between the pre and postoperative levels of Human Leptin (p = 0.002), perilipin-1(p = 0.001), adipolin (p < 0.001), adiponectin (p < 0.001), resistin (p = 0.001), visfatin (p < 0.001), and estrone (p = 0.004) (r = ?0.43, ?0.47, 0.75, 0.84, ?0.47, - 0.58, ?0.41, respectively)ConclusionsOmentectomy affected the postoperative blood levels of adipokines in obese patients with endometrial cancer. As omentectomy may have some positive effects on metabolism in these patients, it may be considered during endometrial cancer surgery due to the possible positive metabolic effects.  相似文献   
70.
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