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   235211篇
  免费   6388篇
  国内免费   570篇
耳鼻咽喉   3361篇
儿科学   10180篇
妇产科学   6576篇
基础医学   29916篇
口腔科学   6899篇
临床医学   17885篇
内科学   42426篇
皮肤病学   5677篇
神经病学   14011篇
特种医学   11807篇
外国民族医学   97篇
外科学   35559篇
综合类   2416篇
一般理论   21篇
预防医学   18359篇
眼科学   5708篇
药学   17658篇
  2篇
中国医学   480篇
肿瘤学   13131篇
  2021年   1469篇
  2020年   1103篇
  2019年   1171篇
  2018年   4961篇
  2017年   4894篇
  2016年   4548篇
  2015年   6228篇
  2014年   6329篇
  2013年   5690篇
  2012年   13010篇
  2011年   7847篇
  2010年   4097篇
  2009年   5353篇
  2008年   4207篇
  2007年   4994篇
  2006年   5098篇
  2005年   12906篇
  2004年   14277篇
  2003年   9612篇
  2002年   4646篇
  2001年   5161篇
  2000年   2444篇
  1999年   6430篇
  1992年   7237篇
  1991年   7460篇
  1990年   7720篇
  1989年   7296篇
  1988年   6784篇
  1987年   6507篇
  1986年   6212篇
  1985年   5475篇
  1984年   3781篇
  1983年   3045篇
  1982年   1075篇
  1980年   915篇
  1979年   3938篇
  1978年   2439篇
  1977年   1878篇
  1976年   1628篇
  1975年   2544篇
  1974年   3164篇
  1973年   2810篇
  1972年   2811篇
  1971年   2807篇
  1970年   2615篇
  1969年   2488篇
  1968年   2289篇
  1967年   2184篇
  1966年   1926篇
  1965年   1139篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Background: The current disadvantages (high cost, toxicity, resistance) of chemotherapy for gastric cancer opted people for alternative therapy from natural source. Curcumin (natural product) possess multiple biological activities but low bio-availability limits their uses as therapeutic. The Nano-formulation of curcumin increased the bioavailability and productivity of anti-cancer and anti-bacterial properties. The present study was initiated to determine the anti-cancer and anti-bacterial effect of Nano curcumin against gastric cancer and H. pylori. Methods: Curcumin loaded PLGA nanoparticles (CUR-NPs) was prepared by single emulsion solvent evaporation method. The MIC were determined using agar dilution method to find the anti-H. Pylori activity of Nano curcumin. The cytotoxicity of Nano curcumin was evaluated by MTT assay and the apoptotic effect (cell cycle arrest and morphology change) was shown by PI staining and microscopy. Results: The MIC of nanocurcumin and curcumin for all four H. pylori strains were 8 µg/ml and 16 µg/ml respectively. The inhibition rate of gastric cancer cells after treatment with curcumin was increased from 6% to 67% for 24h, from 8% to 75% for 48h, from 10% to 83% for 72h. In case of nanocurcumin, the inhibition rate increased from 7% to 69% for 24h, 11% to 87% for 48h and 16% to 97% for 72h. The IC50 of curcumin and Nano-curcumin were 24.20 µM and 18.78 µM respectively for 72 h. The population of cells in sub-G0 population increased from 4.1% in the control group to 24.5% and 57.8% when treated with curcumin and nanocurcumin respectively. After 72h of treatment with nanocurcumin, the apoptotic cells population increased as compared to native curcumin treated cells. Conclusion: The Nano curcumin might be used as a potential therapeutics against gastric cancer and H. Pylori. There is need of further in vivo study in order to validate CUR-NPs activity.  相似文献   
3.
Objective: The objective of this study was to determine the efficacy of curcumin in combination with  intralesional dexamethasone with hyaluronidase in the treatment of oral submucous fibrosis (OSF). Methods: This randomized, double blind, parallel design, clinical trial was conducted at B.P. Koirala Institute of Health Sciences, Nepal. Thirty-four patients with clinically diagnosed OSF were randomized into two groups (17 participants in each) with baseline treatment of intralesional dexamethasone with hyaluronidase for 6 weeks for the both. Curcumin (2gm/day) was provided to Group A (Test) and Group B (Control) received placebo. Interincisal mouth opening, tongue protrusion, cheek flexibility and visual analogue scale (VAS) scoring of burning sensation of oral mucosa was recorded at baseline, 6, 8 and 12 weeks follow-up and independent t-test was used to compare the improvements in two groups. Results: On comparing the 6 weeks and baseline values, in Group A and B the mean difference in mouth opening was 8.82±1.33 mm and 5.53±1.17 mm respectively (p<0.001), in cheek flexibility was 2.94±1.02 mm and 1.94±1.24 mm respectively (p=0.02) and in tongue protrusion was 6.23±1.48 and 3.65±1.37 mm respectively (p<0.001). The findings were consistent in the 8 weeks follow-up. In 12 weeks follow-up, on comparing with the baseline values, in Group A and B, the mean difference in mouth opening was 8.71±1.16 mm and 5.35±1.22 mm respectively (<0.001), ), in cheek flexibility was 2.81±1.01 mm and 1.76±1.35 mm respectively (p=0.02) and in tongue protrusion was 6.06±1.48 and 3.35±1.50 mm respectively (p<0.001). Both the arms showed 100% improvement in burning sensation in 6, 8 and 12 weeks follow-up. Conclusion: Curcumin in combination with intralesional dexamethasone with hyaluronidase is efficacious in the treatment of OSF.  相似文献   
4.
5.
Knox  Joseph A.  Kumar  Vishal  Conrad  Miles B.  Nanavati  Sujal  Moore  Teri  Wilson  Mark 《Emergency radiology》2022,29(3):605-609
Emergency Radiology - Access to multi-detector computed tomography (MDCT) scanning for interventional procedures can prove to be logistically challenging as resources are often in different areas...  相似文献   
6.
7.
The aim of this safety study in mice was to determine in vivo toxicity and biodistribution potential of a single and multiple doses of L-glutamic acid-g-p(HEMA) polymeric nanoparticles as a drug delivery system. The single dose did not cause any lethal effect, and its acute oral LD50 was >2.000 mg/kg body weight (bw). Multiple doses (25, 50, or 100 mg/kg bw) given over 28 days resulted in no significant differences in body and relative organ weights compared to control. These results are supported by biochemical and histological findings. Moreover, nanoparticle exposure did not result in statistically significant differences in micronucleus counts in bone marrow cells compared to control. Nanoparticle distribution was time-dependent, and they reached the organs and even bone marrow by hour 6, as established by ex vivo imaging with the IVIS® spectrum imaging system. In conclusion, L-glutamic acid-g-p(HEMA) polymeric nanoparticles appear biocompatible and have a potential use as a drug delivery system.KEY WORDS: biocompatibility, blood biochemistry, genotoxicity, histology, in vivo toxicity, micronucleus test, polymers  相似文献   
8.
Virtual reality is a form of high-fidelity simulation that may be used to enhance the quality of medical education. We created a bespoke virtual reality trainer software using high resolution motion capture and ultrasound imagery to teach cognitive-motor needling skills necessary for the performance of ultrasound-guided regional anaesthesia. The primary objective of this study was to determine the construct validity between novice and experienced regional anaesthetists. Secondary objectives were: to create learning curves for needling performance; compare the virtual environment immersion with other high-fidelity virtual reality software; and compare cognitive task loads imposed by the virtual trainer compared with real-life medical procedures. We recruited 21 novice and 15 experienced participants, each of whom performed 40 needling attempts on four different virtual nerve targets. Performance scores for each attempt were calculated based on measured metrics (needle angulation, withdrawals, time taken) and compared between the groups. The degree of virtual reality immersion was measured using the Presence Questionnaire, and cognitive burden was measured using the NASA-Task Load Index. Scores by experienced participants were significantly higher than novices (p = 0.002) and for each nerve target (84% vs. 77%, p = 0.002; 86% vs. 79%, p = 0.003; 87% vs. 81%, p = 0.002; 87% vs. 80%, p = 0.003). Log–log transformed learning curves demonstrated individual variability in performance over time. The virtual reality trainer was rated as being comparably immersive to other high-fidelity virtual reality software in the realism, possibility to act and quality of interface subscales (all p > 0.06) but not in the possibility to examine and self-performance subscales (all p < 0.009). The virtual reality trainer created workloads similar to those reported in real-life procedural medicine (p = 0.53). This study achieved initial validation of our new virtual reality trainer and allows progression to a planned definitive trial that will compare the effectiveness of virtual reality training on real-life regional anaesthesia performance.  相似文献   
9.
Microbial co-infections are another primary concern in patients with coronavirus disease 2019 (COVID-19), yet it is an untouched area among researchers. Preliminary data and systematic reviews only show the type of pathogens responsible for that, but its pathophysiology is still unknown. Studies show that these microbial co-infections are hospital-acquired/nosocomial infections, and patients admitted to intensive care units with invasive mechanical ventilation are highly susceptible to it. Patients with COVID-19 had elevated inflammatory cytokines and a weakened cell-mediated immune response, with lower CD4+ T and CD8+ T cell counts, indicating vulnerability to various co-infections. Despite this, there are only a few studies that recommend the management of co-infections.  相似文献   
10.
ABSTRACT

Background

The link of acute pancreatitis (AP) with Incretin based therapies (IBTs) in type 2 diabetes has existed since United States Food and Drug Administration alert in 2010. This issue still remains unresolved due to conflicting results among studies.  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