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   4494篇
  免费   428篇
  国内免费   33篇
耳鼻咽喉   65篇
儿科学   125篇
妇产科学   181篇
基础医学   453篇
口腔科学   173篇
临床医学   341篇
内科学   1046篇
皮肤病学   203篇
神经病学   205篇
特种医学   218篇
外国民族医学   6篇
外科学   735篇
综合类   82篇
一般理论   1篇
预防医学   302篇
眼科学   94篇
药学   417篇
中国医学   25篇
肿瘤学   283篇
  2023年   25篇
  2022年   143篇
  2021年   214篇
  2020年   133篇
  2019年   213篇
  2018年   253篇
  2017年   201篇
  2016年   206篇
  2015年   212篇
  2014年   256篇
  2013年   283篇
  2012年   344篇
  2011年   387篇
  2010年   243篇
  2009年   202篇
  2008年   197篇
  2007年   193篇
  2006年   156篇
  2005年   172篇
  2004年   152篇
  2003年   108篇
  2002年   104篇
  2001年   25篇
  2000年   27篇
  1999年   37篇
  1998年   20篇
  1997年   20篇
  1996年   26篇
  1995年   15篇
  1994年   15篇
  1993年   12篇
  1992年   35篇
  1991年   14篇
  1990年   20篇
  1989年   9篇
  1988年   21篇
  1987年   22篇
  1986年   14篇
  1985年   23篇
  1984年   11篇
  1982年   13篇
  1980年   12篇
  1979年   18篇
  1978年   10篇
  1976年   10篇
  1971年   12篇
  1970年   10篇
  1969年   9篇
  1968年   8篇
  1967年   12篇
排序方式: 共有4955条查询结果,搜索用时 15 毫秒
61.
BACKGROUND: Crohn's disease, an inflammatory bowel disease in humans, has a suspected aetiology of Mycobacterium avium subsp. Paratuberculosis. AIMS: To evaluate the role of rifabutin and clarithromycin anti-Mycobacterium avium subsp. Paratuberculosis treatment in Crohn's disease patients using an open clinical trial. METHODS:. A total of 36 patients with acute presentations of Crohn's disease, whose sera tested positive against p35 and p36 antigens (two recombinant proteins of Mycobacterium avium subsp. Paratuberculosis), were selected for treatment with rifabutin and macrolide antibiotic therapy Rifabutin and macrolide antibiotic therapy medications included 250 mg 1 po bid clarithromycin and 150 mg 1 po bid Ri-fabutin accompanied with a probiotic. Crohn's disease patients' response to rifabutin and macrolide antibiotic therapy was monitored over a period ranging from 4 to 17 months. RESULTS: Seven patients (19.4%) withdrew from the study since they were unable to tolerate medications. Of the remaining 29 patients, 21 (58.3%) reached a sustained state of improvement, traditionally defined as a decrease of 70 points between their entrance and exit Crohn's disease activity index scores together with the absence of the need of all other Crohn's medications, such as immunosuppressants and corticosteroids. Three Crohn's disease patients [8. 3%) noticed significant improvements, but required other Crohn's medications, concurrently with rifabutin and macrolide antibiotic therapy, to achieve and sustain improvement. Only 5 Crohn's disease patients (13.8%) were non-responders, noticing no marked improvement while on rifabutin and macrolide antibiotic therapy. CONCLUSION: The data add further evidence to support the role of rifabutin and macrolide antibiotic therapy in the treatment of Crohn's disease specifically in those patients with evidence of Mycobacterium avium subsp. Paratuberculosis infection. A large multi-centre clinical trial is needed to further explore these findings.  相似文献   
62.
Membranous glomerulonephritis (MGN) is the main cause of nephrotic syndrome in adults and is usually idiopathic. We report a case of nephrotic MGN associated with a myelodysplastic syndrome (MDS) in a 43 year old man. The initial treatment consisted of oral corticosteroids (1 mg/kg/day). Within 3 months proteinuria decreased from 22.4 g/day to 3.96 g/day and the blood cell count was normalized. Renal biopsy disclosed type I MGN. Ponticelli's protocol was started with a favorable effect: negative proteinuria, normal blood cell count and normal bone marrow cellularity. The association between MGN and MDS is quite rate. The possible links between the two conditions are reviewed.  相似文献   
63.
OBJECTIVES: We sought to highlight the clinical, morphologic, and pathogenetic features in patients with a cleft mitral valve (MV). BACKGROUND: Few studies have addressed the morphologic features of cleft MV and the outcome of these patients. The pathogenetic features, including the developmental relation to an atrioventricular (AV) septal defect, remain unclear. METHODS: We reviewed the patients with cleft MV that were diagnosed by echocardiography since 1980. Patients with an AV canal, ventriculo-arterial discordance, and hypoplastic ventricles were excluded. RESULTS: Twenty-two patients were identified at a median age of 0.5 years (range 0 to 10.6). In three patients, no chordal attachments of the cleft to the ventricular septum were seen. Ten patients had significant mitral regurgitation (MR), and three had subaortic obstruction by the cleft. Associated cardiac lesions and extracardiac features were present in 13 and 10 patients, respectively. During the median follow-up period of 1.5 years (range 0 to 11.8), two patients died of extracardiac causes, and one neonate died of severe subaortic obstruction. Surgical repair was performed in 10 patients at a median age of 5.2 years (range 1.3 to 10.6). Multivariate analysis showed no predictors for MV surgery. One patient was re-operated for mitral stenosis associated with aortic valve stenosis. Follow-up echocardiography demonstrated moderate MR in two unoperated patients and moderate MV stenosis in two operated patients. CONCLUSIONS: A cleft of the MV comprises a wide spectrum. Important morphologic differences exist with an AV septal defect, although the two lesions may be pathogenetically related. Surgical repair always seems possible. Long-term echocardiographic follow-up is warranted.  相似文献   
64.
A series of new fluoroquinolone conjugates 8a–g and 9a–f were synthesized via benzotriazole‐mediated synthetic approach with good yield and purity. Some of the synthesized analogs exhibited significant antibacterial properties against Escherichia coli and Staphylococcus aureus with potency higher than that of the parent drugs through in vitro standard bioassay procedure (conjugates 8c and 8d reveal antimicrobial properties with potency 1.9, 61.9, 20.7 and 2.4, 37.1, 8.3 folds relative to the parent antibiotic 6 against E. coli, S. aureus, and Enterococcus faecalis, respectively). The observed experimental data were supported by enzymatic DNA gyrase inhibitory property. Developed BMLR‐QSAR model validates the observed experimental data and recognizes the parameters responsible for the enhanced antibacterial properties.  相似文献   
65.
66.
Natural use of language involves at least two individuals. Some studies have focused on the interaction between senders in communicative situations and how the knowledge about the speaker can bias language comprehension. However, the mere effect of a face as a social context on language processing remains unknown. In the present study, we used event-related potentials to investigate the semantic and morphosyntactic processing of speech in the presence of a photographic portrait of the speaker. In Experiment 1, we show that the N400, a component related to semantic comprehension, increased its amplitude when processed within this minimal social context compared to a scrambled face control condition. Hence, the semantic neural processing of speech is sensitive to the concomitant perception of a picture of the speaker’s face, even if irrelevant to the content of the sentences. Moreover, a late posterior negativity effect was found to the presentation of the speaker’s face compared to control stimuli. In contrast, in Experiment 2, we found that morphosyntactic processing, as reflected in left anterior negativity and P600 effects, is not notably affected by the presence of the speaker’s portrait. Overall, the present findings suggest that the mere presence of the speaker’s image seems to trigger a minimal communicative context, increasing processing resources for language comprehension at the semantic level.  相似文献   
67.
68.
ObjectivesTo compare the effect of various degrees of decalcification after orthodontic treatment (white spot lesions) on orthodontists'', general dentists'', and laypersons'' ratings of smile esthetics.Materials and MethodsEight photographs representing incrementally altered tooth decalcification lesions of maxillary anterior teeth ranging from mild to severe were shown randomly to the study participants. Photographs were rated by a matched sample of orthodontists (N = 42), general dentists (N = 52), and laypeople (N = 58). A visual analogue scale (VAS) was used to assess perceptions of smile esthetics.ResultsThe three groups of raters could distinguish between different decalcification levels. Raters gave more negative scores as the decalcification level increased.ConclusionsThe three groups of raters were able to distinguish between various degrees of decalcification lesions. General dentists were the most critical of all groups when rating decalcification lesions.  相似文献   
69.
A simple, cost-effective and green mucilage-capped silver nanoparticles (Mucilage-AgNPs) modified glassy carbon electrode (GC) composite was constructed for efficient and facile electrochemical oxidation of glucose for the first time. Mucilage-AgNPs were synthesized through the direct chemical reduction of Ag+ by mucilage extracted from Opuntia ficus-indica. Mucilage-AgNPs were identified and characterized using ultraviolet-visible spectroscopy, transmission electron microscopy and square wave voltammetry. Modification of the GC with AgNPs was carried out via a transfer-sticking technique with an immobilization time of 1 h. The Mucilage-AgNPs/GC composite was studied as a possible anode for glucose oxidation in a biofuel cell. The composite resulted in glucose oxidation with a current density and power density of 85.7 μA cm−2 and 25.7 μW cm−2, respectively. Glucose sensing using the Mucilage-AgNPs/GC composite was achieved successfully via two pathways: glucose oxidation and AgNP inhibition. The glucose oxidation-based sensor showed a lower detection limit of 0.01 mM and a linear range of 0.01 to 2.2 mM. The AgNPs inhibition-based sensor provides an indirect determination pathway of glucose with a detection limit of 0.1 mM and a linear range of 0.1 to 1.9 mM. AgNP inhibition is a novel pathway that could be used for determining a large number of organic and inorganic molecules. Overall, the Mucilage-AgNPs/GC is considered a pioneering composite for glucose sensing and fuel cell applications.

A simple, cost-effective and green mucilage-capped silver nanoparticles (Mucilage-AgNPs) modified glassy carbon electrode (GC) composite was constructed for efficient and facile electrochemical oxidation of glucose for the first time.  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