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   1513篇
  免费   46篇
耳鼻咽喉   40篇
儿科学   74篇
妇产科学   77篇
基础医学   164篇
口腔科学   36篇
临床医学   93篇
内科学   359篇
皮肤病学   74篇
神经病学   116篇
特种医学   23篇
外科学   192篇
综合类   8篇
预防医学   71篇
眼科学   45篇
药学   87篇
中国医学   1篇
肿瘤学   99篇
  2019年   1篇
  2015年   3篇
  2014年   9篇
  2013年   3篇
  2012年   108篇
  2011年   129篇
  2010年   35篇
  2009年   36篇
  2008年   194篇
  2007年   203篇
  2006年   163篇
  2005年   152篇
  2004年   153篇
  2003年   157篇
  2002年   97篇
  2001年   7篇
  2000年   7篇
  1999年   13篇
  1998年   10篇
  1997年   13篇
  1996年   9篇
  1995年   5篇
  1994年   5篇
  1993年   7篇
  1992年   4篇
  1991年   6篇
  1990年   1篇
  1989年   2篇
  1987年   1篇
  1986年   1篇
  1984年   1篇
  1983年   3篇
  1982年   1篇
  1981年   3篇
  1980年   1篇
  1979年   2篇
  1977年   2篇
  1976年   1篇
  1973年   2篇
  1972年   6篇
  1971年   3篇
排序方式: 共有1559条查询结果,搜索用时 0 毫秒
41.
42.
Knowledge about vitamin D has greatly improved during the last few years. Vitamin D cannot any more be considered as exclusively necessary to prevent ricket/osteomalacia. Its role in the prevention of some osteoporotic fractures in the elderly (in association with calcium nutrition) is now well demonstrated and many epidemiologic and laboratory data argue for a role in the prevention of several diseases or anomalies (cancer, auto-immune diseases, cardiovascular events, sarcopenia...). A few intervention studies confirming some of these effects also exist. Vitamin D status can easily be assessed by measuring serum 25 hydroxy vitamin D (25OHD) level. However, many experts have claimed that the population-based reference values for 25OHD are too low and that the cut-off value below which vitamin D insufficiency can be present is somewhere between 20 and 40 ng/mL with a clear tendency to target values above 30 ng/mL (75 nmol/L). The main consequences are that vitamin D insufficiency is highly frequent whereas the currently recommended supplementation doses are not sufficient.  相似文献   
43.
Depression is a core symptom of methamphetamine (METH) withdrawal during the first several weeks of abstinence. However, the precise mechanisms underlying METH withdrawal symptoms remain unknown. Brain-derived neurotrophic factor (BDNF) and its specific receptor, tropomyosin-related kinase (TrkB), have a role the in pathophysiology of depression. In this study, we examined the role of BDNF–TrkB signaling in different brain regions of male mice with METH withdrawal symptoms. Repeated METH (3 mg kg−1 per day for 5 days) administration to mice caused a long-lasting depression-like behavior including anhedonia. Western blot analysis showed that BDNF levels in the nucleus accumbens (NAc) of METH-treated mice were significantly higher than those of control mice whereas BDNF levels in other regions, including the prefrontal cortex and hippocampus, were not altered. METH-induced depression-like behavior, behavioral sensitization and dendritic changes in the NAc shell were improved by subsequent subchronic administration of TrkB antagonist ANA-12 (0.5 mg kg−1 per day for 14 days), but not TrkB agonist 7,8-dihydroxyflavone (10 mg kg−1 per day for 14 days). In vivo microdialysis showed that METH (1 mg kg−1)-induced dopamine release in NAc shell of METH-treated mice was attenuated after subsequent subchronic ANA-12 administration. Interestingly, a single bilateral infusion of ANA-12 into the NAc shell, but not NAc core, showed a rapid and long-lasting therapeutic effect. However, ketamine and paroxetine had no effect. These findings suggest that increased BDNF–TrkB signaling in the NAc shell has an important role in the behavioral abnormalities after withdrawal from repeated METH administration, and that TrkB antagonists are potential therapeutic drugs for withdrawal symptoms in METH abusers.  相似文献   
44.
Familial inflammatory inclusion body myositis   总被引:1,自引:0,他引:1       下载免费PDF全文
OBJECTIVE: To compare familial inflammatory inclusion body myositis (IBM) with hereditary inclusion body myopathies and sporadic IBM. PATIENTS AND METHODS: Clinical, biological, MRI, and histological data were analysed in two siblings with inflammatory IBM and compared with those of patients with sporadic and hereditary IBM. RESULTS: Both patients had a clinical phenotype of sporadic IBM, which differs from hereditary myopathies because of late age of onset--respectively 65 and 66 years, and different pattern of muscular involvement--asymmetric, mainly distal but also involving quadriceps. MRI showed selective fatty infiltration and oedema in the extensor compartment of thigh muscles. The diagnosis of IBM was confirmed by muscle biopsy, showing muscle fibres containing numerous rimmed vacuoles, a characteristic shared by all types of IBM. In contrast with hereditary IBM, histological analysis also showed inflammatory mononuclear infiltrate invading non-necrotic fibres, ragged red and oxidase c negative fibres, and positive Congo red staining. Moreover, HLA class II typing disclosed DR beta 1 0301 haplotype, which is significantly related to sporadic but not to hereditary IBM. With steroid treatment and monthly intravenous immunoglobulins, the disease was stabilised in both patients at protracted follow up. CONCLUSION: Sporadic and familial inflammatory IBM share the same clinical, biological, MRI, and histological features.  相似文献   
45.
Pregnancy is widely authorized in systemic lupus erythematosus (SLE). Fertility is similar in SLE and in the general population although the age of menarche seems higher. Some cases of sterility might be attributed to SLE because of autoimmune ovaritis or antiphospholipid antibodies (aPL). These antibodies might lead to endothelial activation and thrombosis by influencing homeostasis, complement activation, inhibition of protein C and annexin V. They might have a deleterious effect on embryonic implantation by adhesion to the trophoblast, inhibition of invasion and placentation and decreased hCG production. The most important part of sterility seems secondary to the use of cyclophosphamide and might be prevented by acetate leuprolide administration. Maternal morbidity seems correlated to SLE activity (controlled by pregnancy planning), hypertension, preeclampsia, Hemolysis, Elevated Liver Enzymes, Low Platelets (HELLP) syndrome, therapy and aPL. Hydroxychloroquine (HCQ) should be maintained throughout pregnancy. Aspirin is prescribed alone in patients with asymptomatic aPL and in addition to heparin if there is a history of thrombosis or fetal loss with aspirin. Fetal and neonatal morbidity correlate with prematurity, adverse effects or maternal steroid therapy and maternal anti-SSA antibodies with 1 to 2% risk of congenital atrioventricular block. Abnormal obstetrical echography-doppler examination is the best predictor of pregnancy outcome. Abnormal ombilical artery flow on the second trimester echodoppler examination and history of thrombophlebitis predict fetal or neonatal death. Abnormal uterine notch on the second trimester echodoppler examination predicts adverse pregnancy outcome. Except for the preventive therapy of congenital atrioventricular block, modalities of SLE pregnancy monitoring and therapy are now well established.  相似文献   
46.
Park JC  Lee SM  Kim JC  Yun JH  Cho KS  Im GI  Kim BS  Kim CS 《Oral diseases》2012,18(6):537-547
Oral Diseases (2012) 18, 537–547 Objective: The human periodontal ligament stem cells (hPDLSCs) and human alveolar bone–derived stromal cells (hABCs) seem to be closely involved in the maintenance of alveolar bone in an anatomically indirect manner; however, there is little study on this matter. Therefore, the effect of hPDLSCs on the osteoclastogenic, osteogenic, and adipogenic differentiation of hABCs was evaluated, focusing on the humoral factors released by hPDLSCs. Materials and methods: Human periodontal ligament stem cells and hABCs were isolated and characterized. hPDLSCs were indirectly cocultured to observe the in vitro effect of humoral factors released from hPDLSCs on the osteoclastogenic, osteogenic, and adipogenic differentiation of hABCs. Human gingival fibroblasts (hGFs) were utilized as positive control. Results: Isolated cells demonstrated the presence of stem cells within. Indirect coculture of hPDLSCs greatly inhibited osteoclastogenesis by hABCs. Osteogenesis/adipogenesis of hABCs was also inhibited by indirect coculture with hPDLSC. The magnitude of regulatory effect from hPDLSCs was significantly greater than that of hGFs. Conclusions: Humoral factors released from hPDLSCs seemed to modulate the differentiation of hABCs, and the osteoclastogenic, osteogenic, and adipogenic differentiation of hABCs was all inhibited, suggesting the potential role of hPDLSCs in the maintenance of the alveolar bone.  相似文献   
47.

Introduction

N-methyl-D-aspartate receptor antibody (anti-NMDA-r AB) encephalitis has been recently identified. We report two cases illustrating the clinical features, response to immunomodulatory treatment and involvement of B-lymphocytes that characterizes this disorder.

Case reports

These patients illustrated the classic clinical features of anti-NMDA-r AB encephalitis including occurrence in young female, presence of severe neurological and psychiatric manifestations with confusion, seizures, mutism, hypovigilence and involuntary movements, and inflammatory cerebrospinal fluid. Both patients improved after immunotherapy. In case 1, the encephalitis was associated with an ovarian teratoma containing neuronal elements. In case 2, there was no tumor identified. A brain biopsy showed prominent perivascular B-cells infiltrates with some T-cells distributed in the brain parenchyma.

Conclusion

Anti-NMDA-r AB encephalitis is certainly not rare and needs to be promptly recognized and treated. An associated neoplasia is inconstant and the pathophysiology involves humoral immunity.  相似文献   
48.
The aims of this study were to describe the clinical, biological and radiological features of community-acquired (CA) Legionnaires' disease (LD) and identify the predictors of mortality in hospitalised patients. Demographic data, risk factors, clinical and biological features, medical management, complications, and outcome from 540 hospitalised patients with confirmed CA LD were prospectively recorded. 8.1% of patients (44 out of 540) died. The predictors of survival after Kaplan-Meier analysis were male sex (p = 0.01), age <60 yrs (p = 0.02), general symptoms (p = 0.006), intensive care unit (ICU) stay (p<0.001), and class II-III Pneumonia Severity Index score (p = 0.004). Six predictors of death were identified by multivariate analysis: age (per 10-yr increment) (relative hazard (RH) 1.50, 95% CI 1.21-1.87), female sex (RH 2.00, 95% CI 1.08-3.69), ICU admission (RH 3.31, 95% CI 1.67-6.56), renal failure (RH 2.73, 95% CI 1.42-5.27), corticosteroid therapy (RH 2.54, 95% CI 1.04-6.20) and C-reactive protein (CRP) >500 mg · L(-1) (RH 2.14, 95% CI 1.02-4.48). Appropriate antibiotic therapy was prescribed for 70.8% (292 out of 412) of patients after admission and for 99.8% (537 out of 538) of patients after diagnosis confirmation. In conclusion, female sex, age, ICU stay, renal failure, corticosteroid treatment and increased level of CRP are significant risk factors for mortality in CA LD.  相似文献   
49.
The improvement of respiratory symptoms for emphysematous patients by surgery is a concept that has evolved over time. Initially used for giant bullae, this surgery was then applied to patients with diffuse microbullous emphysema. The physiological and pathological concepts underlying these surgical procedures are the same in both cases: improve respiratory performance by reducing the high intrapleural pressure. The functional benefit of lung volume reduction surgery (LVRS) in the severe diffuse emphysema has been validated by the National Emphysema Treatment Trial (NETT) and the later studies which allowed to identify prognostic factors. The quality of the clinical, morphological and functional data made it possible to develop recommendations now widely used in current practice. Surgery for giant bullae occurring on little or moderately emphysematous lung is often a simpler approach but also requires specialised support to optimize its results.  相似文献   
50.
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