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   3831篇
  免费   414篇
  国内免费   3篇
耳鼻咽喉   31篇
儿科学   97篇
妇产科学   117篇
基础医学   473篇
口腔科学   106篇
临床医学   379篇
内科学   574篇
皮肤病学   195篇
神经病学   391篇
特种医学   220篇
外国民族医学   1篇
外科学   520篇
综合类   151篇
一般理论   21篇
预防医学   327篇
眼科学   127篇
药学   343篇
中国医学   13篇
肿瘤学   162篇
  2021年   48篇
  2020年   50篇
  2019年   70篇
  2018年   64篇
  2017年   45篇
  2016年   57篇
  2015年   61篇
  2014年   95篇
  2013年   106篇
  2012年   173篇
  2011年   156篇
  2010年   95篇
  2009年   98篇
  2008年   150篇
  2007年   161篇
  2006年   170篇
  2005年   151篇
  2004年   168篇
  2003年   145篇
  2002年   124篇
  2001年   120篇
  2000年   126篇
  1999年   106篇
  1998年   34篇
  1997年   26篇
  1996年   40篇
  1995年   43篇
  1994年   30篇
  1993年   39篇
  1992年   93篇
  1991年   94篇
  1990年   101篇
  1989年   83篇
  1988年   71篇
  1987年   77篇
  1986年   84篇
  1985年   82篇
  1984年   67篇
  1983年   62篇
  1982年   46篇
  1981年   35篇
  1980年   38篇
  1979年   44篇
  1978年   43篇
  1977年   42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4248条查询结果,搜索用时 0 毫秒
41.
42.
A 67-year-old woman with lymphoma presented with a neuromyopathy following "laetrile" (amygdalin) treatment. She had significant elevation of blood and urinary thiocyanate and cyanide levels. Sural nerve biopsy specimen revealed a mixed pattern of demyelination and axonal degeneration, the latter being prominent. Gastrocnemius muscle biopsy specimen showed histochemically a mixed pattern of denervation and myopathy with Type II atrophy. It is concluded that cyanide toxicity secondary to laetrile therapy and nutritional deficiency caused the neuromyopathy, as the changes in peripheral nerve are similar to changes described in ataxic polyneuropathy occurring in Nigeria attributed to high cyanide content in the diet and nutritional deficiency. Although this patient received vincristine initially, the development of the neuromyopathy had no temporal relationship to its administration. The clinical profile, as well as peripheral nerve and muscle changes were not similar to either vincristine neuromyopathy or neuromyopathy due to paraneoplastic manifestation of lymphoma. Clinical improvement following discontinuation of "laetrile" by the patient further supports the toxic etiologic results for the neuromyopathy in this patient.  相似文献   
43.
44.
45.
46.
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   
47.
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   
48.
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   
49.
50.
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   
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