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   1789篇
  免费   231篇
  国内免费   246篇
耳鼻咽喉   4篇
儿科学   8篇
妇产科学   8篇
基础医学   117篇
口腔科学   44篇
临床医学   106篇
内科学   126篇
皮肤病学   18篇
神经病学   37篇
特种医学   184篇
外国民族医学   1篇
外科学   102篇
综合类   362篇
预防医学   161篇
眼科学   10篇
药学   264篇
  1篇
中国医学   560篇
肿瘤学   153篇
  2024年   2篇
  2023年   20篇
  2022年   38篇
  2021年   78篇
  2020年   64篇
  2019年   55篇
  2018年   53篇
  2017年   84篇
  2016年   105篇
  2015年   81篇
  2014年   146篇
  2013年   191篇
  2012年   174篇
  2011年   179篇
  2010年   130篇
  2009年   116篇
  2008年   117篇
  2007年   111篇
  2006年   91篇
  2005年   85篇
  2004年   55篇
  2003年   48篇
  2002年   52篇
  2001年   33篇
  2000年   24篇
  1999年   11篇
  1998年   9篇
  1997年   15篇
  1996年   14篇
  1995年   9篇
  1994年   9篇
  1993年   9篇
  1992年   10篇
  1991年   8篇
  1990年   5篇
  1989年   8篇
  1988年   3篇
  1987年   8篇
  1986年   2篇
  1985年   8篇
  1984年   3篇
  1983年   2篇
  1979年   1篇
排序方式: 共有2266条查询结果,搜索用时 31 毫秒
1.
《Vaccine》2022,40(26):3490-3494
The current WHO Recommendations to assure the quality, safety and efficacy of live attenuated yellow fever vaccines were adopted in 2010. This document recommends that vaccine virus master and working seed lots should be tested for viscerotropism, immunogenicity and neurovirulence in monkeys. A vaccine manufacturer has reported, recently, discrepancies on the clinical scoring of monkeys during assessment of working seed lots and suggested aligning neurotropism assessment of yellow fever vaccines virus seed lots with that of neurovirulence testing of polio vaccines virus seed lots. In this approach, clinical signs are recorded but do not form part of the assessment or pass/fail criteria. At its 71st meeting in August 2020, the ECBS agreed to establish a drafting group and to consult with manufacturers and other stakeholders on the proposed amendment. Then a survey had been conducted to seek opinions of stakeholders on the neurotropism testing and revision of current WHO Recommendations for yellow fever vaccines. It was recognized from the answers of the survey that the test for neurovirulence in monkeys presents several technical challenges which could be addressed in the amended version of the Recommendations.On 18–19 March 2021, a virtual WHO working group meeting was held to discuss a proposed draft of the amended text with participants of yellow fever vaccine manufacturers and relevant regulators. Overall, there was a consensus among manufacturers and regulators that clinical evaluation provides important information and should be retained as part of the neurotropism test. However, there was also agreement that the test is somewhat subjective, and that analysis can be difficult. It was recognized that there was potential for improvement in both test execution and analysis to increase harmonization between manufacturers. Alternative tests to the non-human primates neurovirulence test would be useful but it was agreed that none seem to be sufficiently developed at present. Based on these working group discussions, it was proposed that the appendix on neurotropism test to be further revised by the WHO drafting group and submitted to ECBS for review and adoption.Issues other than neurotropism test were discussed in the meeting as well. There were a number of points identified during the meeting, such as new platform of production, animal models, deep sequencing, international standards, that are outside the current recommendations that are worthy of further discussion. Therefore, it is recommended that there would be a future meeting with various stakeholders to discuss the potential revision of the whole Recommendations for yellow fever vaccines in order to meet the current needs.  相似文献   
2.
The present study deals with the evaluation of antiaging potential of carrot seed oil-based cosmetic emulsions. Briefly, cosmetic emulsions composed of carrot seed oil in varying proportions (2, 4, and 6% w/v) were prepared using the hydrophile–lipophile balance (HLB) technique. Coconut oil, nonionic surfactants (Tween 80 and Span 80), and xanthan gum were used as the oil phase, emulgent, and emulsion stabilizer, respectively. The formed emulsions were evaluated for various physical, chemical, and biochemical parameters such as the zeta potential, globule size measurement, antioxidant activity, sun protection factor (SPF), skin irritation, and biochemical studies. The zeta potential values ranged from ?43.2 to ?48.3, indicating good stability. The polydispersity index (PDI) of various emulsion formulations ranged from 0.353 to 0.816. 1,1-Diphenyl-2-picrylhydrazyl- (DPPH) and nitric oxide-free radical scavenging activity showed the antioxidant potential of the prepared carrot seed oil emulsions. The highest SPF value (6.92) was shown by F3 having 6%w/v carrot seed oil. Histopathological data and biochemical analysis (ascorbic acid (ASC) and total protein content) suggest that these cosmetic emulsions have sufficient potential to be used as potential skin rejuvenating preparations.  相似文献   
3.
郭雨凡  任淑珍  李敏  谢燕 《中草药》2020,51(20):5137-5147
目的制备含功能性油的水飞蓟宾超饱和自纳米乳(SLB-S-SNEDDS),并对其进行表征及体外评价研究,以提高难溶性药物水飞蓟宾的生物利用度。方法铁氢化钾还原力与1,1-二苯基-2-苦肼基(DPPH)自由基清除实验筛选功能性油脂;伪三元相图考察乳化剂乳化能力;测定粒径、多分散指数(PDI)、Zeta电位等考察混合油相比例与载药量;相容性与溶出度实验筛选促过饱和物质并考察其质量浓度;从外观、粒径分布、自乳化效率、形态学等方面表征SLB-S-SNEDDS,并进行溶出度、抗氧化能力、细胞毒性等体外评价。结果所得SLB-S-SNEDDS处方为(1)小麦胚芽油/Capryol 90-Cremophor ELP-Transcutol HP与(2)沙棘籽油/Capryol 90-Cremophor ELP-Transcutol HP,1 g基质(包含0.043 g小麦胚芽油或沙棘籽油、0.387 g Capryol 90、0.380 g Cremophor ELP、0.190 g Transcutol HP),水飞蓟宾的添加量为各组分平衡溶解度之和的20%,Soluplus的添加量为上述总质量的0.1%。小麦胚芽油、沙棘籽油体系分别为淡黄色、亮黄色透明状均一液体,2种体系自乳化分散后均呈近球形白色扁平乳滴,粒径约为50 nm,乳化时间均为65 s。与药物原料及SLB-SNEDDS相比,SLB-S-SNEDDS中水飞蓟宾的累积溶出率8h内均维持在85%~110%,表明该体系能够显著提高药物的溶出度。SLB-S-SNEDDS与铁氰化钾反应后的吸光度(A值0.452~0.782,0.488~0.765)以及DPPH自由基清除率(39.09%~96.02%,30.54%~89.20%)均高于相应质量浓度下水飞蓟宾原料的A值与清除率(0.411~0.760,22.89%~63.21%),表明2种处方体系均能提高水飞蓟宾的抗氧化能力。细胞毒性实验结果显示,在5、10μmol/L药物浓度下,水飞蓟宾原料组、水飞蓟宾S-SNEDDS组及其相应的空白S-SNEDDS组细胞生存率均90%,说明SLB-S-SNEDDS及其所用辅料对人克隆结肠腺癌细胞(Caco-2)毒性较小、安全性较好。结论制备的含功能性油SLB-S-SNEDDS在提高水飞蓟宾累积溶出率的同时,增强了其抗氧化能力,为将超饱和自纳米乳(S-SNEDDS)用于改善难溶性药物水溶性及其生物活性提供有益参考。  相似文献   
4.
目的:研究植物-土壤反馈对刺五加幼苗根、茎、叶次生代谢产物的影响。方法:通过温室盆栽试验,分别对未种植过刺五加的土壤(1组),连续3年种植刺五加的土壤(2组)和多年种植刺五加的土壤(3组),分别种植刺五加1年生幼苗,并对其根、茎、叶的次生代谢产物进行分析。结果:L-苯丙氨酸,原儿茶酸,刺五加苷B,绿原酸,咖啡酸,刺五加苷E,异嗪皮啶,芦丁,金丝桃苷,槲皮素在多年生长刺五加土壤种植,对刺五加幼苗叶和根均有显著性差异,但在茎中绿原酸和刺五加苷E无显著性差异。其中刺五加苷E,异嗪皮啶,芦丁和金丝桃苷在多年生刺五加土壤种植的幼苗叶中未检出。在刺五加幼苗的根中,多数次生代谢产物呈现正反馈;在刺五加幼苗的茎中,咖啡酸,刺五加苷E,金丝桃苷,槲皮素呈现负反馈;在刺五加幼苗的叶中多数次生代谢产物呈现正反馈。结论:植物和土壤在刺五加幼苗生长过程不同部位呈现出不同的反馈情况,整体而言,未种植过刺五加的土壤对刺五加幼苗的次生代谢产物更具优势。研究结果为阐述植物-土壤反馈对刺五加的影响提供研究基础,并为人工栽培刺五加提供了理论依据和技术支持。  相似文献   
5.
目的:研究甘草种子、种苗质量分级标准,为甘草药材规范化生产奠定基础。方法:以全国主产区所流通的甘草种子、种苗为样本,通过收集种子的发芽率、净度、含水量、千粒质量,种苗的根长、芦头直径和百株质量等指标信息,采用K-均值聚类分析法、标准差法、平均值法并结合生产实践对甘草种子、种苗进行分级,并开展田间栽培比较试验,对等级划分的合理性进行验证。结果:甘草种子质量等级划分为3个等级,各级甘草种子的千粒质量不低于8 g,含水量不低于10%,一级种子:发芽率≥90%,净度≥90%;二级种子:90%>发芽率≥85%,90%>净度≥85%;三级种子:85%>发芽率≥80%,85%>净度≥80%。甘草种苗质量等级划分为3个等级,一级种苗:根长≥45 cm,芦头直径≥0.8 cm,1.3 kg≤百株质量<0.8 kg;二级种苗:45 cm>根长≥35 cm,0.8 cm>芦头直径≥0.6 cm,0.8 kg≤百株质量<0.4 kg;三级种苗:35 cm>根长≥25 cm,0.6 cm>芦头直径≥0.4 cm,0.4 kg≤百株质量≤0.2 kg。结论:经验证,甘草种子、种苗质量等级划分合理,便于生产实践应用。  相似文献   
6.
目的探讨生大黄贴敷神阙穴配合莱菔子热熨,预防经皮肾镜钬激光碎石术后患者腹胀便秘的效果。方法选取2015年1月—2019年12月收治的行经皮肾镜钬激光碎石术后患者100例,随机分为试验组50例,对照组50例;在临床护理方法相同的基础上试验组采用生大黄加75%酒精调贴敷神阙穴配合莱菔子热熨。结果2组患者腹胀便秘发生率比较差异有统计学意义(P<0.05),试验组发生腹胀便秘发生率明显低于对照组。结论生大黄贴敷神阙穴配合莱菔子热熨有效地预防经皮肾镜钬激光碎石术后患者腹胀、便秘,促进患者康复。  相似文献   
7.
Helicobacter pylori is a major risk factor for gastritis, gastric ulcers and gastric cancer. Traditional therapy with proton pump inhibitor and antibiotics is regarded as optimal for H. pylori eradication whereas, the eradication rate is unsatisfactory. Studies have reported that cranberry may inhibit H. pylori adhesion to the human gastric mucus but lack of other berry extracts have been evaluated in clinical study. Thus, a 9-week add-on randomised controlled trial was conducted to explore the impact of blueberry and grape seed extract (BGE) combinations traditional therapy for H. pylori eradication. In results, we found that there was no significant difference of eradication rate between the berry extract group and placebo group in the intention-to-treat analysis and in the per-protocol analysis (94.64% versus 84.62%, p?=?0.085). Diarrhoea, constipation and epigastric pain were observed increasing during ingestion of the berry extract in some cases. In conclusion, this study indicated that no significant difference existed between the BGE extract group and placebo group in eradication rate under triple therapy.  相似文献   
8.
IntroductionMagseed is an alternative method of localising non-palpable breast lesions that has addressed many of the limitations of wire guided localisation (WGL). It consists of a paramagnetic seed that can be visualised on mammography and ultrasound. Intraoperative localisation of the seed is achieved with the use of the Sentimag probe. The aim of this study was to prospectively compare localisation in patients undergoing wide local excision (WLE) for non-palpable lesions between Magseed and WGL.MethodsWe prospectively collected data on all patients undergoing image-guided WLE between October 2017 and September 2018 in two academic breast units with a planned accrual of 100 consecutive patients undergoing Magseed localisation. Data was also collected on a cohort of 100 consecutive patients undergoing WGL in the same time period.ResultsDemographic and disease characteristics were well balanced between the two groups. 4/104 patients were converted preoperatively from Magseed to WGL (2 misplaced Magseeds; 2 undetected Magseeds). Intraoperative identification and excision of the localised lesion was successful in all patients as confirmed with specimen radiography. Overall no significant differences were observed in the proportion of patients requiring re-excision between the two groups (Magseed 16% vs. WGL 14% p = 0.692). Specimens size by weight and volume was similar for both groups (Magseed 39.6 g vs. WGL 44.5 g p = 0.206 and 90.1 cm3 for Magseed vs. 95.6 cm3 for WGL p = 0.579).ConclusionsIn our series Magseed localisation proved to be as reliable and effective as WGL in terms of lesion identification, excision with tumour free margins and specimen weight.  相似文献   
9.
The aim of this systematic review and meta‐analysis was to analyze the effects of grape seed extract (GSE) on glycemic control and serum lipoproteins, inflammation and body weight. Two independent authors systematically searched online databases including EMBASE, Scopus, PubMed, Cochrane Library, and Web of Science from inception until May 30, 2019. Cochrane Collaboration risk of bias tool was applied to assess the methodological quality of included trials. The heterogeneity among the included studies was assessed using Cochrane's Q test and I‐square (I2) statistic. Data were pooled using a random‐effects model and weighted mean difference (WMD) was considered as the overall effect size. Fifty trials were included in this meta‐analysis. Pooling effect sizes from studies demonstrated a significant decrease in fasting plasma glucose (FPG) (WMD): ?2.01; 95% confidence interval (CI): ?3.14, ?0.86), total cholesterol (TC; WMD: ?6.03; 95% CI: ?9.71, ?2.35), low‐density lipoprotein (LDL) cholesterol (WMD: ?4.97; 95% CI: ?8.37, ?1.57), triglycerides (WMD: ?6.55; 95% CI: ?9.28, ?3.83), and C‐reactive protein (CRP) concentrations (WMD: ?0.81; 95% CI: ?1.25, ?0.38) following GSE therapy. Grape seed did not influence HbA1c, HDL cholesterol levels, and anthropometric measurements. This meta‐analysis demonstrated that GSE intake significantly reduced FPG, TC, LDL cholesterol, triglycerides, and CRP levels.  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