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   1608篇
  免费   94篇
  国内免费   57篇
耳鼻咽喉   26篇
儿科学   38篇
妇产科学   18篇
基础医学   171篇
口腔科学   46篇
临床医学   166篇
内科学   446篇
皮肤病学   34篇
神经病学   48篇
特种医学   101篇
外科学   221篇
综合类   55篇
一般理论   1篇
预防医学   98篇
眼科学   49篇
药学   126篇
中国医学   29篇
肿瘤学   86篇
  2023年   9篇
  2022年   29篇
  2021年   44篇
  2020年   29篇
  2019年   64篇
  2018年   48篇
  2017年   36篇
  2016年   42篇
  2015年   34篇
  2014年   53篇
  2013年   85篇
  2012年   95篇
  2011年   124篇
  2010年   60篇
  2009年   51篇
  2008年   71篇
  2007年   104篇
  2006年   57篇
  2005年   63篇
  2004年   59篇
  2003年   47篇
  2002年   40篇
  2001年   32篇
  2000年   33篇
  1999年   34篇
  1998年   33篇
  1997年   32篇
  1996年   18篇
  1995年   27篇
  1994年   20篇
  1993年   18篇
  1992年   14篇
  1991年   20篇
  1990年   11篇
  1989年   25篇
  1988年   23篇
  1987年   16篇
  1986年   23篇
  1985年   16篇
  1984年   13篇
  1983年   6篇
  1982年   9篇
  1981年   7篇
  1979年   14篇
  1977年   9篇
  1976年   9篇
  1975年   9篇
  1974年   8篇
  1969年   5篇
  1968年   6篇
排序方式: 共有1759条查询结果,搜索用时 10 毫秒
991.
992.
993.
Is there a "Barrett's iceberg?"   总被引:2,自引:0,他引:2  
Shaheen N 《Gastroenterology》2002,123(2):636-639
  相似文献   
994.
995.
BACKGROUND: We recently reported links between frequent paracetamol (acetaminophen) use and wheezing and asthma in adults and children, but data are lacking on possible effects of prenatal exposure on wheezing in early childhood. METHODS: In the population based Avon Longitudinal Study of Parents and Children (ALSPAC) women were asked twice during pregnancy (at 18-20 weeks and 32 weeks) about their usage of paracetamol and aspirin. Six months after birth, and at yearly intervals thereafter, mothers were asked about wheezing and eczema symptoms in their child. The effects of paracetamol and aspirin use in pregnancy on the risk in the offspring of wheezing at 30-42 months (n=9,400) and eczema at 18-30 months (n=10,216) and on their risk of different wheezing patterns (defined by presence or absence of wheezing at <6 months and at 30-42 months) were examined. RESULTS: Paracetamol was taken frequently (most days/daily) by only 1% of women. After controlling for potential confounders, frequent paracetamol use in late pregnancy (20-32 weeks), but not in early pregnancy (<18-20 weeks), was associated with an increased risk of wheezing in the offspring at 30-42 months (adjusted odds ratio (OR) compared with no use 2.10 (95% CI 1.30 to 3.41); p=0.003), particularly if wheezing started before 6 months (OR 2.34 (95% CI 1.24 to 4.40); p=0.008). Assuming a causal relation, only about 1% of wheezing at 30-42 months was attributable to this exposure. Frequent paracetamol use in pregnancy was not associated with an increased risk of eczema. Frequent aspirin use in pregnancy was associated with an increased risk of wheezing only at <6 months. CONCLUSIONS: Frequent use of paracetamol in late pregnancy may increase the risk of wheezing in the offspring, although such an effect could explain only about 1% of the population prevalence of wheezing in early childhood.  相似文献   
996.
Two new triterpenoids, 22,23-dihydronimocinol (1) and desfurano-6alpha-hydroxyazadiradione (2), were isolated from a methanolic extract of the fresh leaves of Azadirachta indica (neem) along with a known meliacin, 7alpha-senecioyl-(7-deacetyl)-23-O-methylnimocinolide. The structures of 1 and 2 were elucidated through spectral and chemical studies. Compounds 1 and 2 showed mortality for fourth instar larvae of the mosquito (Anopheles stephensi), with LC(50) values of 60 and 43 ppm, respectively.  相似文献   
997.
The developing world is facing a real pandemic of renal and cardiovascular disease. With the decrease of infectious disease morbidity and mortality, and the exposure to more westernized life style, signs of increasing renal and cardiovascular disease is particularly shown in the tremendous rise in type 2 diabetes and its sequelae. A group of doctors and scientists from all over the world have convened in Bellagio to halt this dramatic disease change and burden to the developing countries. They came to the conclusion that screening and treatment should clearly focus on cost-beneficial strategies, among which blood pressure and urinary albumin measurement, as well as effective and affordable treatment strategies to lower blood pressure and albuminuria, are essential.  相似文献   
998.
This was a prospective analytical study done from October'99 through December 2000 to observe the clinical profile of epilepsy in children with cerebral palsy. Sixty epileptic children with cerebral palsy were studied and their results were compared with the results of epilepsy in 30 developmentally normal children. Ages of all children studied were 1-15 years. Majority were below five years of age and male out numbered female. Spastic quadriplegia (60%) was the commonest type of cerebral palsy. Generalized tonic-clonic seizure (66%) was the commonest seizure type in both groups. Second most common type of seizure was partial (13%) and myoclonic (29%) in developmentally normal and cerebral palsy children respectively. Mental retardation (63%) and speech delay (58%) were the two common associated problems in cerebral palsy patients. Ventriculomegaly (55%) was the commonest computed tomographic findings in cerebral palsy patients. In electro encephalography generalized epileptiform activity was the commonest finding in both groups. Clinical pattern is different in many ways when epilepsy is associated with cerebral palsy.  相似文献   
999.
OBJECTIVE: To determine the feasibility of open simple prostatectomy with early vascular control in the treatment of benign prostate hyperplasia (BPH), and thus reduce blood loss. PATIENTS AND METHODS: Thirty-seven patients were reviewed from 1991 to 2002; 34 had a Millin's and three a Freyer's prostatectomy performed by one surgeon, with early vascular control. RESULTS: The mean operative duration was 1.3 h and the mean blood loss 841 mL, with a mean decrease in haemoglobin level of 22 g/L. Six (16%) of the patients received a blood transfusion. The mean weight of the prostate removed was 97.8 g; the duration of catheterization and the hospital stay after surgery were 6.21 and 11.7 days, respectively. There was one (3%) death and one case of pulmonary embolism. Three patients (8%) developed stress incontinence. Two failed to void after surgery and one developed acute retention 3 years later. Five patients developed recurrent obstructive symptoms. CONCLUSION: Open simple prostatectomy with early vascular control reduces the amount of blood loss, rendering it a safe option for treating BPH.  相似文献   
1000.
Non-Hodgkin's lymphoma (NHL) belongs to a group of lymphoid neoplasms that is diverse in manner of presentation, response to therapy and prognosis. Usually the oral manifestations of NHL are secondary to a more widespread involvement throughout the body. Though primary intraoral lesions in NHL are uncommon, it is important to be aware of them, since intraoral manifestations are the presenting symptom in these patients. A 55 year old woman presented with a swelling in the maxillary right alveolus and buccal vestibule. There were no palpable lymph nodes. A CT scan revealed a mass on the labial aspect of the right maxilla with no involvement of the maxillary sinus. Incisional biopsy of the lesion showed a dense lymphocytic infiltrate with formation of variably sized lymphoid follicles. The infiltrate showed a mixed neoplastic lymphocyte composition which was suggestive of follicular mixed type of malignant B cell primary extranodal lymphoma. The patient was treated with chemotherapy followed by radiation.  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