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   3972篇
  免费   428篇
  国内免费   7篇
耳鼻咽喉   31篇
儿科学   103篇
妇产科学   121篇
基础医学   485篇
口腔科学   109篇
临床医学   392篇
内科学   627篇
皮肤病学   197篇
神经病学   391篇
特种医学   271篇
外国民族医学   1篇
外科学   522篇
综合类   154篇
一般理论   21篇
预防医学   330篇
眼科学   128篇
药学   346篇
中国医学   13篇
肿瘤学   165篇
  2021年   50篇
  2020年   51篇
  2019年   71篇
  2018年   64篇
  2017年   46篇
  2016年   57篇
  2015年   63篇
  2014年   98篇
  2013年   107篇
  2012年   177篇
  2011年   156篇
  2010年   97篇
  2009年   101篇
  2008年   152篇
  2007年   166篇
  2006年   171篇
  2005年   152篇
  2004年   168篇
  2003年   145篇
  2002年   124篇
  2001年   121篇
  2000年   126篇
  1999年   109篇
  1998年   41篇
  1997年   38篇
  1996年   50篇
  1995年   53篇
  1994年   49篇
  1993年   43篇
  1992年   94篇
  1991年   96篇
  1990年   103篇
  1989年   92篇
  1988年   76篇
  1987年   80篇
  1986年   92篇
  1985年   85篇
  1984年   69篇
  1983年   63篇
  1982年   50篇
  1981年   39篇
  1980年   45篇
  1979年   46篇
  1978年   47篇
  1977年   46篇
  1973年   33篇
  1971年   40篇
  1970年   33篇
  1969年   39篇
  1967年   30篇
排序方式: 共有4407条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
Sunnybrook Health Science Centre is an adult regional trauma unit serving metropolitan Toronto and environs. We undertook a nvo-year retrospective review of patients admitted to our institution with blunt thoracic trauma. Three hundred and thirty-three patients with blunt trauma and an injury severity score (ISS) greater than 17 required emergency surgery. Of these, 208 had blunt thoracic injuries while 125 did not have chest injuries. Both groups were similar with respect to age but patients with thoracic trauma had a greater ISS. (P < 0.05) and greater intraoperative mortality (P < 0.01). The aetiology of the intraoperative deaths with one exception was exsanguination. Emergency thoracotomy or sternotomy indicated a poor prognosis with a mortality rate of 80%. The most common intraoperative problem was an elevated airway pressure. Awake intubation was undertaken in 77.5% of patients requiring anaesthesia and surgery because of the potentially compromised airways and difficult intubations due to the nature of the associated injuries. Finally, 74% of patients undergoing urgent surgery required mechanical postoperative ventilation. The presence of blunt chest trauma should be considered a marker of the severity of injury sustained by the patient.  相似文献   
65.
BACKGROUND AND PURPOSE: Stroke patients in western countries frequently have coronary artery disease (CAD). In black Africans, CAD has been reported as being rare in both stroke patients and the general population. In this study, an attempt has been made to determine the prevalence of CAD in a black South African stroke population. METHODS: The prevalence of CAD was determined by indicators identified through a series of 5 observational studies in black patients diagnosed with stroke. CAD indicators included (1) bedside diagnosis in 741 patients; (2) resting ECG in 555 consecutively admitted patients; (3) a combination of clinical examination, cardiac ultrasound, radionuclide scintigraphy, and multigated blood pool studies in 102 consecutively admitted patients; (4) thallium scintigraphy in 60 patients; and (5) necropsy in 23 patients. RESULTS: On bedside questioning, only 0.7% complained of previous angina. There was no history given of myocardial infarction (MI), but documentation of this was found in the clinical notes of 0.7% of the patients. In the resting ECG study, evidence of myocardial ischemia was present in 14.6% and MI in 2.1%. In the combined study, cardiac ischemia was documented on ECG in 12.7% of patients and evidence of previous MI in 5.8%. Cardiac scintigraphic studies revealed changes of myocardial ischemia in 31.7% and MI in 13.3% of the 60 patients studied. Four (17.4%) of 23 patients in the necropsy study had histological evidence of previous MI, and 50% of all patients had evidence of >50% atherosclerotic stenosis in 1, 2, or 3 coronary arteries. CONCLUSIONS: The prevalence of CAD in black African stroke patients is significantly higher than has been documented in the general nonstroke black population as well as in stroke patients. Black stroke patients may have a risk for CAD similar to that of their white counterparts.  相似文献   
66.
The alpha-synuclein (alpha SN) protein is thought to play a central role in the pathogenesis of neurodegenerative diseases where it aggregates to form intracellular inclusions. We have used Western blotting to examine the expression levels and solubility of alpha SN in brain homogenates from dementia with Lewy bodies (DLB), Parkinson's disease (PD), Alzheimer's disease (AD), and normal controls using samples from the parahippocampus/transentorhinal cortex. Compared to controls, DLB brains accumulate significantly greater amounts of sodium dodecyl sulfate (SDS)-soluble and SDS-insoluble alpha SN but levels of TBS-soluble alpha SN did not change. Levels of synaptophysin, a marker of synaptic integrity, were significantly lower in DLB cases than in normal aged controls regardless of whether concurrent changes of AD were present. This limbic synaptic dysfunction may contribute to cognitive impairment in DLB. Whether aggregated alpha SN is a cause or effect of the disease process in DLB and PD remains to be determined, but the presence of aggregated alpha SN is consistent with a pathogenesis similar to that associated with aggregates of Abeta amyloid in AD.  相似文献   
67.
68.
Longitudinal studies of osteoporosis in older persons may underestimate bone loss because of a lack of follow-up measurements on subjects too frail to return. The authors addressed this possible bias as part of the population-based Framingham Study; in 1996-1997, they used quantitative ultrasound to assess the bone status of elderly subjects regardless of their ability to return to the clinic. Broadband ultrasound attenuation (BUA) and speed of sound of the calcaneus (heel) were measured in 433 subjects at the Framingham, Massachusetts, clinic and in 167 subjects at their homes or nursing homes. All ultrasound parameters were measured with intramachine coefficients of variation of <6.0%. The mean BUA for those subjects evaluated at the clinic was higher than for those measured at home (9.2% higher for men, p = 0.081; 8.6% higher for women, p = 0.034). After adjustment for age and weight, the differences in BUA were no longer significant. Among the elderly subjects participating in this longitudinal cohort study, those who were unable to return for follow-up were older, weighed less, and had a lower BUA than those who did return, suggesting that longitudinal studies of changes in bone mass with aging may underestimate the true population values.  相似文献   
69.
Osteochondritis dissecans of the patellofemoral joint   总被引:1,自引:0,他引:1  
Osteochondritis dissecans of the patellofemoral joint is an uncommon condition that may be the cause of anterior knee pain or crepitus. We present the clinical features of 37 patients with osteochondritis dissecans lesions of the patellofemoral joint (24 on the patella, 13 on the trochlear groove), including two patients with medial trochlear groove lesions, which have not, to our knowledge, been previously reported. The osteochondral lesions involved the convex articular surfaces. The median age of patients when first examined was 15 years, and 54% of patients had open epiphyses. These lesions were more common in male patients than in female patients (four-to-one ratio). Osteochondritis dissecans of the patellofemoral joint can be overlooked unless quality radiographs are viewed with care and, at arthroscopy, both the patella and trochlear groove are assessed. Treatment depends on the symptoms, site, and nature of the lesion and the patient's age. Nonoperative management includes patellar taping and vastus medialis obliquus muscle exercises. Operative intervention is indicated for patients with mechanical symptoms and includes arthroscopy, consisting of chondroplasty and removal of loose bodies, and lateral retinacular release. In this study treatment generally improved the symptoms, but patients with articular cartilage loss had persistent patellofemoral crepitus and discomfort.  相似文献   
70.
To date qualitative studies of IgA in the cerebrospinal fluid in neurological disease, particularly multiple sclerosis, have been few and given mixed results. The aim of this study was to identify local synthesis of IgA by detection of clonal IgA bands, in a large cohort of patients with a variety of neurological disorders, using polyacrylamide gel electrophoresis, transfer of protein to nitrocellulose membranes and specific staining. Of 2,097 sequentially analysed patients with suspected neurological disease 54 (2.6%) had locally synthesised IgA; most notably, IgA was present in 39 of 291 (13%) patients with suspected multiple sclerosis. The latter group also had a significant excess of light-chain production, particularly free kappa, when compared to multiple sclerosis patients without local synthesis of IgA. Locally synthesised IgA was also demonstrated in inflammatory, infectious and autoimmune diseases of the central nervous system. This qualitative technique is simple and suitable for routine analysis of cerebrospinal fluid, and further qualitative studies of IgA may be useful in investigating the pathophysiology of certain neurological disorders.  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