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   518篇
  免费   29篇
  国内免费   22篇
耳鼻咽喉   1篇
儿科学   54篇
基础医学   63篇
口腔科学   13篇
临床医学   82篇
内科学   112篇
皮肤病学   13篇
神经病学   30篇
特种医学   108篇
外科学   27篇
综合类   7篇
预防医学   18篇
药学   29篇
肿瘤学   12篇
  2021年   2篇
  2019年   5篇
  2018年   3篇
  2017年   3篇
  2016年   4篇
  2015年   5篇
  2014年   10篇
  2013年   21篇
  2012年   9篇
  2011年   16篇
  2010年   25篇
  2009年   16篇
  2008年   12篇
  2007年   29篇
  2006年   11篇
  2005年   13篇
  2004年   4篇
  2003年   6篇
  2002年   5篇
  2001年   8篇
  2000年   7篇
  1999年   14篇
  1998年   40篇
  1997年   42篇
  1996年   36篇
  1995年   17篇
  1994年   25篇
  1993年   16篇
  1992年   14篇
  1991年   8篇
  1990年   9篇
  1989年   10篇
  1988年   27篇
  1987年   11篇
  1986年   8篇
  1985年   7篇
  1984年   10篇
  1983年   8篇
  1982年   14篇
  1981年   9篇
  1980年   6篇
  1978年   3篇
  1977年   5篇
  1976年   4篇
  1975年   2篇
  1954年   2篇
  1952年   1篇
  1948年   1篇
  1947年   1篇
  1943年   1篇
排序方式: 共有569条查询结果,搜索用时 15 毫秒
51.
福建省高校贫困大学生心理健康水平与人格特征   总被引:1,自引:0,他引:1  
目的:了解贫困生的心理健康现状和人格特征。方法:于2005-09/11随机抽取福州大学、福建师范大学、福建农林大学、福建中医学院、闽江学院2002-2004级学生2400名。男1478名,女922名,平均(20±1)岁。根据2004-11-04福建省福州市政府办公厅正式下发的《福州市人民政府关于提高城区城镇及农村居民最低生活保障标准的通知》中的规定,即城镇多人户每人每个月210元、单人户230元;农村多人户每人每月155元、单人户175元,本文把家庭人均月收入较少,有一定数额债务,只能缴纳部分学杂费,基本生活费接近于当地居民最低生活保障线(如上规定,本文以230元为基准)的学生定为“贫困生”。采用精神症状自评量表和16种人格因素问卷对高校贫困生的心理健康和人格特征进行调查。结果:发放问卷2400份,收回有效问卷2111份。其中贫困生539份。①贫困生精神症状自评量表的躯体化、强迫、人际敏感、抑郁、焦虑、敌对、恐怖、偏执、精神病性、其他、总症状指数得分均高于非贫困生(贫困生:1.61±0.56,2.02±0.64,1.92±0.63,1.71±0.56,1.65±0.58,1.73±0.68,1.57±0.62,1.81±0.65,1.67±0.54,1.76±0.63,1.74±0.49;非贫困生:1.48±0.45,1.89±0.56,1.79±0.57,1.61±0.51,1.54±0.50,1.61±0.56,1.44±0.49,1.66±0.54,1.54±0.46,1.61±0.53,1.62±0.41,P<0.01)。男女贫困生之间各因子分差异均不显著(P>0.05)。②福建省高校贫困大学生的心理问题检出率为24.5%,其中轻度心理问题(2≤因子分<3)为22.6%;中度心理问题(3≤因子分<4)为1.7%;重度心理问题(4≤因子分<5)为0.2%。心理问题以强迫、人际敏感、偏执、忧郁、敌对、焦虑等心理问题最为突出。③16种人格因素问卷中,贫困生乐群性、聪慧性、兴奋性、敏感性、怀疑性上得分低于非贫困生,有恒性、忧虑性、独立性得分高于非贫困生(贫困生:5.20±1.77,4.70±1.93,5.49±1.87,6.46±1.79,4.29±1.71,4.60±1.63,6.64±1.82,5.07±1.82;非贫困生:5.39±1.74,4.95±1.99,5.82±1.91,6.66±1.75,4.55±1.77,4.36±1.69,6.43±1.94,4.89±1.77,P<0.05~0.01)。④影响贫困生心理健康水平的主要人格因素按其影响作用从大到小有怀疑性、忧虑性、稳定性、兴奋性、自律性。结论:福建省高校贫困大学生的心理健康状况令人担忧,其人格特征对心理健康水平有重要影响。  相似文献   
52.
目的:探讨体外诱导骨髓间充质干细胞向胰岛素分泌细胞分化的可能性,并观察其动态变化。方法:实验于2005-09/2007-03在山东大学齐鲁医院完成。①标本来源:骨髓标本15例来自山东大学齐鲁医院成人骨髓检查结果正常者,均签署捐献同意书。②实验方法:无菌条件下取骨髓2.0~5.0mL,采用percoll分离液和贴壁法获得纯化的成人骨髓间充质干细胞。③实验评估:流式细胞仪行细胞表面抗原检测,在适当的条件下诱导其分化为成骨细胞和脂肪细胞。采用两步法向胰岛素分泌细胞诱导,观察其在碱性成纤维细胞生长因子、活化素A、胰岛素样生长因子、尼克酰胺等因子刺激下向胰岛素分泌细胞分化的动态变化。双硫踪染色鉴定胰岛样细胞团,酶联免疫吸附试验检测细胞分泌胰岛素的情况,RT-PCR检测胰岛细胞特异基因的表达。结果:①骨髓间充质干细胞的生长特性及免疫表型:分离培养获得的贴壁细胞,呈形态均一的梭形,流式细胞仪检测CD34、CD45表达阴性,CD29、CD44表达阳性。②向成骨细胞和脂肪细胞的诱导分化:此类细胞经茜素红染色、油红O染色均呈阳性,可诱导分化为成骨细胞和脂肪细胞。③向胰岛素分泌细胞的诱导分化:第1步诱导后出现细胞簇,双硫腙染色不着色,胰岛素分泌量少,仅检测到PDX-1基因的表达,证实其为胰岛前体细胞。第2步诱导后细胞簇数目逐渐上升,至诱导14d大部分细胞簇经双硫腙染色都呈红色。④诱导后培养上清中胰岛素含量:诱导第3,7,14,21天的胰岛素分泌量分别为(15.3±4.9),(34.1±5.6),(40.4±5.3),(39.8±5.1)mU/L。⑤胰岛细胞特异基因的表达:诱导7d仅检测到PDX-1基因的表达,insulin1、insulin2和Glut2基因均不表达。诱导14,21d检测到insulin2、PDX-1基因表达,insulin1基因弱表达,Glut2基因不表达。结论:体外分离、纯化得到的骨髓间充质干细胞诱导7d可分化出胰岛前体细胞,不具功能性;诱导14d后可成功地分化出成熟的具有功能性的胰岛素分泌细胞。  相似文献   
53.
54.
目的:探讨乳腺癌组织中核呼吸因子-1(NRF-1)蛋白表达与乳腺癌发生、发展及临床病理特征的关系。方法:采用免疫组化EnVision二步法,对211例乳腺癌组织和50例乳腺良性病变组织中NRF-1蛋白表达进行检测。结果:NRF-1蛋白表达定位于细胞核,着色呈棕黄色,乳腺癌中阳性表达(82.7%)低于乳腺良性病变组织阳性表达(100%),χ2=100.288,P=0.000;高分化乳腺癌NRF-1阳性率明显高于中、低分化乳腺癌(χ2=16.242,P=0.001;χ2=72.802,P=0.000),中分化乳腺癌也明显高于低分化乳腺癌,χ2=30.190,P=0.000。乳腺癌淋巴结转移患者NRF-1蛋白阳性表达率明显低于未转移者,χ2=12.025,P=0.007;TNM分期中I期NRF-1蛋白阳性表达率明显高于Ⅱ、Ⅲ期,χ2=12.025,P=0.007。结论:NRF-1蛋白的表达可能与乳腺癌的发生发展密切相关,可作为乳腺癌患者疾病进展监控和预后观测的指标,具有临床应用价值。  相似文献   
55.
Strand L, Jenkins A, Grude N, Allum A‐G, Mykland H‐C, Nowrouzian FL, Kristiansen B‐E. Emergence of fluoroquinolone‐resistant clonal group A: clonal analysis of Norwegian and Russian E. coli isolates. APMIS 2010; 118: 571–77. We describe a study of urinary tract and intestinal isolates of Escherichia coli from Norway and Russia using automated ribotyping, single nucleotide polymorphism analysis for clonal group A (CgA) supplemented with phylogrouping, virulence gene profiling and resistance profiling. CgA comprised 19% of the Norwegian UTI isolates from 2001. Two highly multiresistant fluoroquinolone‐resistant CgA isolates were found. Ribotypes clustered into four major and six minor groups (ribogroups). Fluoroquinolone‐resistant isolates and phylogroups A and B1 were associated with ribogroup RA. Ribogroup RB predominated among Russian UTI isolates and was predominantly phylogroup A and depleted in P‐fimbriae. Ribogroup RC predominated among Norwegian UTI isolates and was rich in virulence factors (S‐fimbriae, haemagglutinin and haemolysin) and predominantly phylogroup B2 and D. Ribogroup RG was associated with CgA and predominantly phylogroup D. Ribogroups RD, RE and RF had too few members for statistical analysis. The correlation between ribotype and phylogenetic group was not as strong as reported in other studies.  相似文献   
56.
白花丹参化学成分的研究   总被引:30,自引:0,他引:30  
从白花丹参(Salvia miltiorrhiza f.alba)中分离出14个二萜醌类化合物,其中2个为新化合物,由光谱分析推定为1,2,15,16-四氢丹参醌(Ⅰ)和丹参醛(Ⅱ);另一个化合物Ⅲ与R0-090680的结构相同。化合物Ⅰ和Ⅲ对淋巴白血病细胞P388均有较强的抑制作用。  相似文献   
57.
OBJECTIVE: To determine nosocomial transmission of respiratory syncytial virus (RSV) in Canadian pediatric hospitals, outcomes associated with nosocomial disease, and infection control practices. DESIGN: A prospective cohort study in the 1992 to 1994 winter respiratory seasons. SETTING: Nine Canadian pediatric university-affiliated hospitals. PARTICIPANTS: Hospitalized children with symptoms of lower respiratory tract infection (at least one of cough, wheezing, dyspnea, tachypnea, and apnea) and RSV antigen identified in a nasopharyngeal aspirate. RESULTS: Of 1516 children, 91 (6%) had nosocomial RSV (NRSV), defined as symptoms of lower respiratory tract infection and RSV antigen beginning >72 hours after admission. The nosocomial ratio (NRSV/[com-munity-acquired RSV {CARSV})] + NRSV) varied by site from 2.8% to 13%. The median length of stay attributable to RSV for community-acquired illness was 5 days, but 10 days for nosocomial illness. Four children with NRSV (4. 4%) died within 2 weeks of infection, compared with 6 (0.42%) with CARSV (relative risk = 10.4, 95% confidence interval: 3.0, 36.4). All sites isolated RSV-positive patients in single rooms or cohorted them. In a multivariate model, no particular isolation policy was associated with decreased nosocomial ratio, but gowning to enter the room was associated with increased risk of RSV transmission (incidence rate ratio 2.81; confidence interval: 1.65, 4.77). CONCLUSIONS: RSV transmission risk in Canadian pediatric hospitals is generally low. Although use of barrier methods varies, all sites cohort or isolate RSV-positive patients in single rooms. Children with risk factors for severe disease who acquire infection nosocomially have prolonged stays and excess mortality.  相似文献   
58.
59.
Histopathology is a major diagnostic tool in dermatology, particularly in psoriasiform diseases. Morphological studies showed that the initial event in psoriatic lesions is perivascular infiltrate, followed by dilatation of superficial papillary vessels. Proliferation of keratinocytes and neutrophil exocytosis are secondary events. Fully developed psoriasis has a very characteristic pattern, which includes elongation of rete ridges leading to regular acanthosis, oedema of the papillary dermis associated with tortuous dilated vessels, thinning of suprapapillar area, decreased thickness of granular layer, and exocytosis of neutrophils in the spinous layer (Kogoj's pustule) or in the cornified parakeratotic layer (Munro microabscesses). Pustular psoriasis is characterized by large or confluent intra‐epidermal multilocular pustules. Whatever the clinical variant of psoriasis, common morphological signs suggest that it is basically a unique pathological process, with many possible presentations according to various factors such as age, size and localization of lesions, or therapy. Similar microscopic elementary lesions indicate that Hallopeau's acrodermatitis continua, Reiter's disease and geographical tongue are variants of psoriasis. Because of the many faces of the disease, psoriasis can resemble many other squamous or pustular disorders. Differential diagnosis by microscopic analysis is based on pattern analysis, PAS (Periodic Acid Schiff) staining to rule out fungal infection, and immunohistochemistry to characterize lymphocytic infiltrate. Psoriasis is one of the most common inflammatory skin diseases. In its characteristic presentation, psoriasis comprises well‐circumscribed red scaly papules and plaques. In this form, the disease is generally easy to identify, especially when the elbows, knees and scalp are affected. Nevertheless, the term ‘psoriasis’ includes more clinical variants than any other inflammatory dermatosis: psoriasis vulgaris vs. pustular, localized vs. generalized, topographic variants, mucous membranes involvement, hair and nail lesions. Although some of these conditions might be extremely different from psoriasis vulgaris, common pathological findings can be identified in all of them. Microscopic analysis of psoriatic lesions may therefore help clinicians to make the diagnosis and to understand that, whatever the clinical presentation, signs and symptoms are mainly due to a unique pathological process.  相似文献   
60.
Ultrasound (US) enhanced with microbubble contrast agents may transiently disrupt the blood-brain barrier (BBB) with minimal damage, providing a technique for noninvasive, localized drug-delivery deep within the brain. The mechanism and temporal profile of disruption are not understood, owing to the limitations of imaging modalities used previously. In this study, we monitored US-induced BBB disruption with multiphoton microscopy, providing high-resolution temporal and spatial information about the permeabilization mechanism and immediate effects of US exposure. Anesthetized C57 mice were prepared with a craniotomy and injected intravenously with fluorescent dyes to permit visualization of the vasculature and BBB integrity. The animals were imaged through a cranial window while exposed to low-intensity US (f=1.029 MHz, power=0.2 W) with a coincident intravenous injection of Optison (a microbubble contrast agent). We observed arteriolar vasoconstriction on US exposure that disrupted blood flow and lasted up to 5 mins; BBB disruption occurred via two characteristically distinct processes-perivascular fluorescence gradually increased (over minutes) along the length of the affected vessel without apparent rupture of the vessel wall or rapidly (seconds) increased in select, focal regions. These data corroborated previous studies suggesting increased endothelial transcytosis and breached tight junctions and demonstrated vasoconstriction, which might alter BBB permeability by modifying cerebral blood flow.  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