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   986篇
  免费   38篇
  国内免费   6篇
耳鼻咽喉   1篇
儿科学   37篇
妇产科学   32篇
基础医学   84篇
口腔科学   17篇
临床医学   151篇
内科学   174篇
皮肤病学   28篇
神经病学   30篇
特种医学   152篇
外科学   97篇
综合类   52篇
预防医学   74篇
眼科学   16篇
药学   28篇
  1篇
中国医学   2篇
肿瘤学   54篇
  2023年   2篇
  2022年   2篇
  2021年   15篇
  2020年   5篇
  2019年   10篇
  2018年   15篇
  2017年   6篇
  2016年   9篇
  2015年   36篇
  2014年   62篇
  2013年   36篇
  2012年   42篇
  2011年   65篇
  2010年   34篇
  2009年   44篇
  2008年   57篇
  2007年   62篇
  2006年   72篇
  2005年   46篇
  2004年   43篇
  2003年   44篇
  2002年   36篇
  2001年   17篇
  2000年   13篇
  1999年   12篇
  1998年   18篇
  1997年   17篇
  1996年   22篇
  1995年   21篇
  1994年   29篇
  1993年   13篇
  1992年   3篇
  1991年   4篇
  1989年   12篇
  1988年   9篇
  1987年   6篇
  1986年   9篇
  1985年   22篇
  1984年   7篇
  1983年   7篇
  1982年   3篇
  1981年   10篇
  1980年   8篇
  1979年   2篇
  1978年   6篇
  1977年   7篇
  1976年   3篇
  1974年   2篇
  1969年   1篇
  1957年   1篇
排序方式: 共有1030条查询结果,搜索用时 15 毫秒
71.
According to current concepts, two processes are responsible for the maintenance of body equilibrium: shifts of the reference point caused by changes in the posture and stabilization of oscillations of the center of mass relative to this point. Exact changes in these processes occurring at various forms of locomotor disorders remain unclear. We proposed an original mathematical method allowing separate evaluation of these two processes responsible for the maintenance of body equilibrium.  相似文献   
72.
OBJECTIVE: To determine the within-host population dynamics of Campylobacter jejuni and Escherichia coli in chickens during and after treatment with fluoroquinolones. MATERIALS AND METHODS: Total and resistant faecal counts were determined from cloacal swabs during and after treatment with enrofloxacin. Chickens were housed individually to avoid confounding as a result of interaction between animals, and to be able to focus solely on the within-host dynamics. To determine the molecular basis of resistance, a number of isolates were checked for mutations in gyrA. RESULTS: Treatment with enrofloxacin at doses routinely prescribed (50 ppm) rapidly reduced the faecal counts of E. coli below the detection limit and did not induce resistance. In C. jejuni, on the other hand, treatment with enrofloxacin quickly selected for high frequencies of fluoroquinolone-resistant strains. In all phenotypically resistant isolates, resistance was traced to mutations in the gyrA gene. CONCLUSIONS: (1) A licensed dosage (50 ppm) of enrofloxacin in drinking water of chickens is effective (i.e. markedly reduced faecal counts) and is safe on a short time scale in E. coli (i.e. did not rapidly select for resistance), but is neither safe nor effective in C. jejuni. (2) The rapid emergence of resistance to quinolones in C. jejuni does not necessarily result from horizontal transmission of resistant strains among chickens, but could solely be the result of de novo selection of resistance in individual chickens.  相似文献   
73.
74.
BACKGROUND: Corticosteroids are routinely used in patients with pulmonary fibrosis. The timing for initiation of treatment is likely to be crucial for corticosteroids to exert an antifibrotic effect. Experimental studies in animals have examined the effect of corticosteroid treatment starting before or at the time of lung injury. However, this is not representative of the human condition as treatment only begins after disease has been established. We examined the effect of a short course corticosteroid treatment starting 3 days after bleomycin induced lung injury on the development of pulmonary fibrosis. METHODS: Bleomycin (1.5 mg/kg) was instilled intratracheally into rats to induce pulmonary fibrosis. The effect of a 3-day course of dexamethasone (0.5 mg/kg) initiated 3 days after bleomycin induced lung injury on cell proliferation and collagen deposition was examined by analysing bronchoalveolar lavage (BAL) fluid and lung tissue. RESULTS: Treating bleomycin exposed animals after injury with dexamethasone for 3 days inhibited lung collagen deposition compared with animals exposed to bleomycin without dexamethasone treatment (15.2 (2.2) mg collagen/lung v 22.5 (2.1) mg/lung; p<0.05). Dexamethasone treatment reduced pulmonary parenchymal cell proliferation in bleomycin exposed rats but did not influence BAL fluid mitogenic activity for lung fibroblasts or alter the BAL fluid levels of the fibrogenic mediators transforming growth factor-beta(1), platelet derived growth factor-AB, and thrombin. CONCLUSIONS: A 3 day course of dexamethasone treatment initiated 3 days after bleomycin induced lung injury reduces lung cell proliferation and collagen deposition by mechanisms other than through reduction of transforming growth factor-beta(1), platelet derived growth factor-AB, and thrombin levels in BAL fluid. We propose that an early short course treatment with dexamethasone may be useful in inhibiting pulmonary fibrosis.  相似文献   
75.
Bladder-sphincter dysfunction in myelomeningocele   总被引:5,自引:0,他引:5  
 Pediatric urodynamics taught us that detrusor-sphincter dyssynergia creates a bladder outlet obstruction in about 50% of any population of children with myelomeningocele. This functional obstruction causes renal damage due to obstructive uropathy, exactly the same way as a congenital anatomical urethral obstruction does. Pediatric urodynamics also taught us that in children with myelomeningocele pelvic floor activity and detrusor activity can be abnormal (hyperactive or inactive) completely independent from each other. These insights have changed the management of myelomeningocele. Children with overactivity of the pelvic floor can be singled out at infant age, and started on clean intermittent catherization, to prevent obstructive uropathy and preserve renal function. Children with detrusor overactivity can be singled out too at very early age, and treated with anticholinergics, to prevent irreversible structural damage to the detrusor and preserve normal bladder capacity and compliance. Received: 20 July 1999 / Accepted: 24 January 2001  相似文献   
76.
OBJECTIVE: To determine to what extent the higher impact of treatment for sexually transmitted diseases (STD) on HIV incidence in Mwanza, Tanzania than in Rakai and Masaka, Uganda might be explained by baseline differences between the trial populations. DESIGN: A re-analysis of baseline data from the three trial populations comparing demography, sexual risk behaviour and HIV/STD epidemiology. METHODS: Data were compared after age-standardization and adjustments for sample selection where necessary. STD rates were also adjusted for the sensitivities and specificities of the diagnostic techniques used. RESULTS: Demographic patterns were similar across populations, apart from effects of AIDS on fertility and mortality (including widowhood) in Uganda. Higher sexual risk behaviours, including younger age of sexual debut, higher numbers of recent partners and lower frequency of condom use, were apparent in Mwanza compared to Masaka and Rakai. High-titre serological syphilis, gonorrhoea, chlamydia infection and trichomoniasis were all more prevalent in Mwanza, except for chlamydia infection in males. There was little difference between sites in the seroprevalence of Herpes simplex virus type-2. Age patterns in the prevalence of short-duration STD and current risk behaviours were similar across sites but all-titre serological syphilis was more prevalent among older participants in Rakai and Masaka than Mwanza. CONCLUSIONS: Differences between trial populations included higher reported risk behaviour and higher rates of curable STD in Mwanza compared to Rakai and Masaka. These differences probably relate to previous reductions in risk behaviour in Uganda and may explain, at least in part, the contrasting results of these trials.  相似文献   
77.
Endomyocardial biopsy was attempted in 18 children aged 5 months to 15 years with 82% success. Biopsies obtained from 15 children were examined by light and electron microscope making positive morphological diagnoses in 3 cases. The biopsy findings were actively helpful in 7 other cases, which contrasts with experience in adult biopsy series. This is a low risk procedure which does not add to the hazards of cardiac catheterization in children.  相似文献   
78.
Two neonates with arrhythmias and the long QT syndrome are described. The arrhythmias were detected in utero and both infants were apparently well after birth. The first infant, although well, had a bradycardia for the first 9 days of life. A normal heart rate was documented at 10 days but a prolonged QT interval was not appreciated on the ECG. He was discharged from hospital but died suddenly and unexpectedly 3 days later. A post-mortem examination failed to find a cause for his death which therefore fell into the category of the sudden infant death syndrome (SIDS). A retrospective analysis of the perinatal electrocardiogram showed a probable junctional rhythm with 2:1 conduction to the ventricle; the QT interval was prolonged at 0.52 seconds (QTC = 0.63). The second infant had a QT interval of 0.52 seconds (QTC = 0.54) and frequent ventricular premature beats on a 24-hour electrocardiogram. She was treated with propranolol and remains well 2 years later. Sudden infant death has often been described in the siblings of children with the long QT syndrome and one other report described a case of SIDS which was said to have had a prolonged QT interval on the perinatal ECG. This report, however, provides unquestionable evidence, in one case, of an association between the long QT syndrome and SIDS.  相似文献   
79.
High-field surface coil magnetic resonance (MR) images were obtained of 12 ankles: two from healthy volunteers, seven from patients, and three from fresh cadavers. The cadaver ankles were sectioned in the coronal, sagittal, and axial planes for direct comparison with the MR images. Plain film confirmation of pathologic conditions was obtained in all patients, and five underwent arthroscopy or surgery, or both. MR imaging provided excellent delineation of ligaments and cartilaginous structures in all cases.  相似文献   
80.
Management of cerebral ischemia due to Takayasu''''s arteritis   总被引:2,自引:0,他引:2  
Aortoarteritis ,alsocalledTakayasu’sarteritis ,isachronicidiopathicinflammatorydiseasethataffectslargeandmediumsizearteries Clinicalfeaturesreflectlimbororganischemiaresultingfromstenosistoobliterationofinvolvedarteries Thisdisease ,describedbyTakayasuin…  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