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   11222篇
  免费   1203篇
  国内免费   782篇
耳鼻咽喉   80篇
儿科学   100篇
妇产科学   148篇
基础医学   1370篇
口腔科学   223篇
临床医学   1572篇
内科学   1649篇
皮肤病学   83篇
神经病学   655篇
特种医学   479篇
外国民族医学   7篇
外科学   1063篇
综合类   2001篇
现状与发展   3篇
一般理论   1篇
预防医学   742篇
眼科学   294篇
药学   1214篇
  22篇
中国医学   708篇
肿瘤学   793篇
  2024年   39篇
  2023年   189篇
  2022年   532篇
  2021年   632篇
  2020年   512篇
  2019年   423篇
  2018年   455篇
  2017年   436篇
  2016年   356篇
  2015年   557篇
  2014年   636篇
  2013年   507篇
  2012年   822篇
  2011年   898篇
  2010年   550篇
  2009年   440篇
  2008年   544篇
  2007年   566篇
  2006年   550篇
  2005年   584篇
  2004年   387篇
  2003年   315篇
  2002年   307篇
  2001年   248篇
  2000年   257篇
  1999年   307篇
  1998年   169篇
  1997年   169篇
  1996年   127篇
  1995年   98篇
  1994年   110篇
  1993年   44篇
  1992年   73篇
  1991年   73篇
  1990年   73篇
  1989年   58篇
  1988年   36篇
  1987年   27篇
  1986年   33篇
  1985年   30篇
  1984年   12篇
  1983年   7篇
  1982年   7篇
  1981年   7篇
  1979年   4篇
  1942年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
lsoflavonoids, formononetin, 9,10-dimethoxypterocarpan 3-O-beta-D-glucoside, ononin, calycosin 7-O-glc and calycosin, were isolated from the roots of Astragalus mongholicus Bunge (Leguminosae). The neuroprotective roles and direct antioxidant effects of these isoflavonoids were investigated by using PC12 cell model and DPPH (1,1-diphenyl-2-picrylhydrazyl) assay. Formononetin, ononin and calycosin were found inhibiting glutamate-induced cell injury, with an estimated 50% effective concentration (EC50) of 0.027 microg/ml, 0.047 microg/ml and 0.031 microg/ml, respectively. Pretreatment with them increased the activities of antioxidant enzymes, including superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and prevented the release of lactate dehydrogenase (LDH) in glutamate-injured PC12 cells. On the other hand, calycosin 7-O-glc and calycosin showed more scavenging activity to DPPH radicals than formononetin in the cell-free system. The inconsistency between the neuroprotective capabilities of isoflavonoids and their directly scavenging activity to DPPH radicals indicated that formononetin, ononin and calycosin probably depended on increasing endogenous antioxidant and stabilizing the cells' membrane structures to inhibit the cell damage induced by glutamate.  相似文献   
43.
目的:了解山东中医药大学附属医院近年来引进的博士研究生的发展现状。方法:采用调查问卷的方法对医院近年来引进且入院满1年的博士研究生进行调查,统计其入院后的科研产出及工作状况,通过内容分析法分析其工作以来遇到的问题及困惑。结果:缺少科研支持、职能部门管理不到位、科室管理不够科学等是造成博士研究生发展困惑的因素,医院在高层次人才培养意识、高层次人才培养机制、高层次人才科研支持力度、对引入的外校高层次人才的人文关怀与心理疏导方面存在不足。结论:医院应增强高层人才培养的意识、健全人才培养的机制、强化人才培养与梯队建设方案的落实监督、为高层次人才提供科研支持、增强对引进高层次人才的人文关怀与心理疏导等,改变高层次人才发展环境。  相似文献   
44.
We aimed to evaluate the prospective association of vitamin B5 with all‐cause mortality and explore its potential modifiers in Chinese adults with hypertension. A nested, case‐control study was conducted in the China Stroke Primary Prevention Trial, including 505 deaths of all causes and 505 matched controls. The median follow‐up duration was 4.5 years. The primary outcome measure in this investigation was all‐cause mortality, which encompassed deaths for any reason. The mean plasma vitamin B5 concentration for cases (43.7 ng/mL) was higher than that in controls (40.9 ng/mL) (p = .001). When vitamin B5 was further assessed as quintiles, compared with the reference group (Q1: < 33.0 ng/mL), the risk of all‐cause mortality increased by 29% (OR = 1.29, 95% CI: 0.83‐2.01) in Q2, 22% (OR = 1.22, 95% CI: 0.77‐1.94) in Q3, 62% (OR = 1.62, 95% CI: 1.00‐2.62) in Q4, and 77% (OR = 1.77, 95% CI: 1.06‐2.95) in Q5. The trend test was significant (p = .022). When Q4‐Q5 were combined, a significant 41% increment (OR = 1.41, 95% CI: 1.03‐1.95) in all‐cause death risk was found compared with Q1‐Q3. The adverse effects were more pronounced in those with normal folate levels (p‐interaction = .019) and older people (p‐interaction = .037). This study suggests that higher baseline levels of plasma vitamin B5 are a risk factor for all‐cause mortality among Chinese patients with hypertension, especially among older adults and those with adequate folate levels. The findings, if confirmed, may inform novel clinical and nutritional guidelines and interventions to optimize vitamin B5 levels.  相似文献   
45.
目的:比较关节镜辅助复位内固定(ARIF)和切开复位内固定(ORIF)治疗胫骨平台骨折的疗效。方法:回顾性分析2016年1月至2018年8月华中科技大学附属协和医院骨科收治的75例胫骨平台骨折患者的资料。男58例,女17例;年龄20~54岁,平均47岁。左侧42例,右侧33例。骨折根据Schatzker分型:Ⅰ型23例...  相似文献   
46.
This study aimed to describe the distribution of water-arsenic (As) valence states and its relationship to areas with endemic arsenism in the Datong basin. Drinking water samples of patients with endemic arsenism and a control group were examined using hydride generation atomic fluorescence spectrometry (HG-AFS). We analyzed the data using SPSS10.0 for Windows. The As(III)/As ratio was 52.1% in the water sample, exceeding the national standard of 0.05 mg/L. The As(III)/As ratio significantly varied among the different stages in the disease-state groups, and with the control group (χ 2 = 22.4, P<0.01). The As(III)/As(V) ratio significantly varied in the four groups (χ 2 = 26.19, P<0.01), with a tendency to increase along with the seriousness of the disease state. The most common type of drinking water arsenic valence state was As(III) in the endemic disease-areas. Endemic arsenism was positively correlated with As(III). This led us to conclude that the fraction of each water-arsenic valence state should be studied when determining the arsenic content of drinking water. Translated from Chinese Journal of Endemiology, 2006, 25(1): 64–66 [译自: 中国地方病学杂志]  相似文献   
47.
目的 通过对甘肃省部分非综合征型聋患者进行聋病易感基因筛查,从分子水平了解其遗传病因及特点.方法 采集甘肃省375例非综合征型聋患者的外周静脉血5~10 ml,提取基因组DNA,运用SNPscan技术检测GJB2基因2个外显子36个突变位点、SLC26A4基因21个外显子77个突变位点和mtDNA12SrRNA A1555G及C1494T突变.结果 375例非综合征型聋患者中,23例携带mtDNA12SrRNA A1555G均质性突变(6.13%, 23/375),2例携带mtDNA12SrRNA C1494T均质性突变(0.53%, 2/375);检出GJB2基因突变致聋者42例(11.20%, 42/375),其中纯合突变31例(8.27%, 31/375)、复合杂合突变11例(2.93%, 11/375),GJB2基因单杂合突变携带者25例(6.67%,25/375),c.235delC为最常见的突变类型,等位基因频率为8.80%(66/750);检出SLC26A4基因突变致聋者29例(7.73%, 29/375),其中纯合突变17例(4.53%, 17/375)、复合杂合突变12例(3.20%, 12/375),SLC26A4基因单杂合突变携带者14例(3.73%,14/375),c.919-2A>G和c.2168A>G为其最主要的突变类型,等位基因频率分别为5.20%(39/750)和2.0%(15/750).结论 甘肃省部分非综合征型聋患者mt DNA12SrRNA A1555G突变检出率明显高于全国水平(2.83%,57/2016),而GJB2、SLC26A4基因突变检出率与全国水平相近;三个常见聋病易感基因筛查可为25.60%的本组耳聋患者提供明确的分子病因学诊断.  相似文献   
48.
目的 观察贴壁法分离提取大鼠乳鼠骨髓间充质干细胞(mesenchymal stem cells,MSCs)并进行体外扩增培养的可行性并探讨其生物学特性,为进一步实验研究作基础.方法 实验2008-01/06于南昌大学第一附属医院泌尿外科研究所完成.贴壁法分离培养SD大鼠乳鼠MSCs,经CD29、CD34、CD44、CD45鉴定MSCs,并绘制不同代数细胞生长曲线和贴壁率曲线分析其生物学特性.结果 ①原代细胞生长潜伏期略长,孵育24 h后小部分圆形单核细胞开始贴壁,48 h可见巢状克隆集落形成,贴壁细胞呈多形性,贴壁3d后增殖加快,9d后基本融合.②生长曲线及贴壁率曲线提示第2至第6代细胞接种存活率基本相同,生长曲线基本一致,而第7代以后细胞的生长速度渐缓,贴壁时间延长,细胞接种存活率也明显降低,并出现衰化现象.③免疫组化鉴定结果 显示CD29、CD44表达基本阳性,而CD34、CD45表达阴性.结论 贴壁法比较容易分离培养MSCs,为组织工程的应用提供了足够的种子来源,MSCs有一定的增殖能力但并不是无限的,而是随传代扩增逐渐衰化,因此了解和掌握MSCs的生物学特性为进一步研究应用打下基础.  相似文献   
49.
Duan P  Cheng J  Lin M  Cai LL  Hu Z  Jin SX  Hu MP 《中华妇产科杂志》2008,43(4):272-275
OBJECTIVE: To study intermediate and long term efficacy of uterine arterial embolization (UAE) with sodium alginate microspheres (KMG) at diameters 500-00 microm in treatment of diffuse adenomyosis. METHODS: Totally 40 patients with standard diffuse adenomyosis were enrolled and treated with UAE. KMG at diameters 500-700 microm for vascular embolization were used to embolize the arteries. The degree of dysmenorrhea, amount of menorrhea and uterine volume, as well as the level of serum CA125, follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2) were investigated before and after UAE. RESULTS: The follow up rates were 100% (40/40), 100% (40/40), 80% (32/40), 68% (27/40), 58% (23/40) after uterine arterial UAE 12, 24, 36, 48 and 60 months respectively. The early, intermediate and long-term effective rates were 90% (36/40), 88% (28/32), 83% (19/23). The degree of dysmenorrhea, the amount of menorrhea and the uterine volume, as well as serum CA125 all decreased significantly 3 months after UAE at varying degrees (P < 0.05). Compared with other follow-up time, the degree of dysmenorrhea and the amount of menorrhea declined to their lowest point at 6 month after UAE (P < 0.01). Paralleled with the decrease of volume of uterine, serum CA125 also decreased significantly and reached the lowest level 12 months later compared with other follow-up times (P < 0.01). Even at the 12th month after UAE serum CA125 was not normal and FSH, LH and E2 did not change all the times after UAE, (P > 0.05). No recurrence was found during the 60 months after UAE. CONCLUSION: KMG used in UAE at diameters 500-700 microm has good intermediate and long term effectiveness in treatment of diffuse adenomyosis with no side effects.  相似文献   
50.
Acutelunginjury(Al.I)whichoccursasacomplicationofacutehemorrhagicnecroticpancreatitis(AHNP)becomesahotprobleminhepatobiliarysurgery.Previousstudiesindicatedthattheaccumulationofpolymorphonuclearneutrophils(PMNs)inthelungsplaysakeyroleinthedamagesofpulmonaryparenchymalcellsandinterstitialedemainAHNPLlj.However,themechanismofPMNaccumulationinthelungsisnotclearlyknown.ThisstudywascarriedoutonaratmodelofAHNPcomplicatedwithAl-I,TheauthorsintendedtoclarifytherelationshipofPMNaccumulationi…  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