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   3252233篇
  免费   231057篇
  国内免费   8421篇
耳鼻咽喉   44806篇
儿科学   107898篇
妇产科学   90276篇
基础医学   458261篇
口腔科学   89574篇
临床医学   296092篇
内科学   633167篇
皮肤病学   78023篇
神经病学   263522篇
特种医学   125653篇
外国民族医学   918篇
外科学   485949篇
综合类   65417篇
现状与发展   6篇
一般理论   1175篇
预防医学   245897篇
眼科学   73689篇
药学   243344篇
  13篇
中国医学   7089篇
肿瘤学   180942篇
  2019年   25493篇
  2018年   36025篇
  2017年   27887篇
  2016年   32220篇
  2015年   36161篇
  2014年   49639篇
  2013年   74245篇
  2012年   99049篇
  2011年   104720篇
  2010年   63005篇
  2009年   60176篇
  2008年   97600篇
  2007年   103839篇
  2006年   105704篇
  2005年   101322篇
  2004年   97355篇
  2003年   93916篇
  2002年   90685篇
  2001年   159348篇
  2000年   163401篇
  1999年   137517篇
  1998年   38864篇
  1997年   34494篇
  1996年   34689篇
  1995年   33513篇
  1994年   30534篇
  1993年   28642篇
  1992年   106380篇
  1991年   102419篇
  1990年   99590篇
  1989年   96348篇
  1988年   88010篇
  1987年   86001篇
  1986年   80895篇
  1985年   76973篇
  1984年   57116篇
  1983年   48134篇
  1982年   28291篇
  1981年   25074篇
  1979年   50565篇
  1978年   35263篇
  1977年   30597篇
  1976年   27779篇
  1975年   30124篇
  1974年   35366篇
  1973年   33749篇
  1972年   31863篇
  1971年   29629篇
  1970年   27242篇
  1969年   26231篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Herniography has been used for 25 years in the diagnosis of occult herniation but has not gained widespread acceptance in the UK, despite studies confirming its high sensitivity and specificity for occult hernias and an excellent record of safety and patient acceptability. The traditional approach in the UK to suspected occult groin herniation has been surgical exploration. This study examined the use of herniography in a single district general hospital to assess its impact in limiting unnecessary groin explorations and allowing discharge of patients without hernias. The case notes of 90 successive patients referred for herniography by the department of general surgery in a single UK district general hospital over an 18-month period were reviewed. Eighty-seven completed examinations were analysed in which 23 hernias were diagnosed in 20 patients. Thirteen patients have undergone hernia repair with resolution of symptoms. There were no false positive examinations, although two inguinal hernias were incorrectly diagnosed radiologically as femoral hernias; there were two false negative examinations where additional hernias were found at laparoscopic repair. There were no reported complications. Twenty-four patients were discharged directly from the surgical clinic after a negative herniogram. Thirty patients were referred to other specialities. No patient had undergone groin exploration after a negative herniogram. Herniography is a useful tool in assessing obscure groin pain and potential occult herniation. It can reliably rule out the presence of a hernia and avoid the need for surgical exploration. Many patients with a negative herniogram can be reassured and discharged, whilst others may be referred on to other specialities safe in the knowledge that an occult hernia has been excluded.  相似文献   
962.
Implantation of parathyroid carcinoma along fine needle aspiration track   总被引:1,自引:0,他引:1  
Introduction Fine needle aspiration cytology is not a commonly employed diagnostic modality in the diagnosis of parathyroid tumors.Case report A 28 year old lady being followed-up for 5 years after en bloc resection of a parathyroid carcinoma presented with a nodule in the lower neck, away from the parathyroidectomy scar. The 1 cm isolated nodule was located in the muscular and subcutaneous plane and corresponded to the needle track of FNA performed on a neck nodule before the parathyroidectomy. On evaluation, she had mild hypercalcemia and high normal serum parathyroid hormone levels. FNAC and histology including immunohistochemistry for Chromogranin A after local excision of the nodule confirmed the nodule to be a recurrent parathyroid carcinoma along the needle track.Discussion To the best of the authors’ knowledge, this is only the second case of needle track implantation after FNA in parathyroid carcinoma reported to date. This case highlights the risk of engraftment of parathyroid tissue after FNA and cautions against the use of FNA as a preoperative diagnostic modality for the evaluation of parathyroid lesions.Drs. Agarwal and Dhingra have contributed equally, as joint first authors.  相似文献   
963.
Introduction The associations between vitamin D receptor (VDR) Bsm I and Fok I genotypes, parity, and risk of osteoporotic hip fracture were evaluated in a statewide population-based case-control study in Utah.Methods Women age 50–89 years with hip fracture (n=882) were ascertained via surveillance of 18 Utah hospitals from 1997 to 2001. Age-matched controls were randomly selected (n=897). Participants were interviewed in their homes, and blood samples were collected for genotyping.Results In logistic regression analyses that controlled for multiple confounders, Bsm I VDR genotype but not Fok I genotype was associated with risk of osteoporotic hip fracture (OR bb vs. BB genotype: 0.68; 95% CI: 0.50, 0.95). In similar analyses, no overall association was observed between parity status and risk of osteoporotic hip fracture. However, the effect of VDR genotype was modified by parity status. Among nulliparous women (n=140), Bsm I genotype was not associated with risk of hip fracture (OR bb vs. BB: 0.82; 95% CI: 0.28, 2.4); among primiparous women (n=133), bb genotype was associated with increased risk of hip fracture (OR bb vs. BB: 3.30; 95% CI: 0.96, 11.29); among multiparous women (n=1,400), bb genotype was associated with decreased risk of hip fracture (OR bb vs. BB: 0.59; 95% CI: 0.42, 0.84).Conclusion VDR Bsm I genotype was associated with risk of hip fracture in Utah women, and this effect was modified by parity status. Hormonal or lifestyle factors related to parity may underlie this interaction.  相似文献   
964.
Poor results after surgery for bronchioloalveolar carcinoma.   总被引:2,自引:0,他引:2  
BACKGROUND: Bronchioloalveolar carcinoma (BAC) is suggested to be less aggressive than other types of lung cancer. To assess the option of treatment modification, actual outcome data were studied and compared with results for other types of lung cancer. METHOD: Retrospective analysis of all consecutive patients who underwent resection for stage I lung cancer in our hospital. For 18 BAC cases, histological specimens were re-evaluated and in three cases diagnosis was revised. RESULTS: In the period 1989 through 2000, 15 patients with BAC and 260 patients with other tumour types underwent surgery in our hospital. Five-year survival rates were 24 and 53%, respectively, (p = 0.01). CONCLUSIONS: Given the poor results after standard surgery, parenchyma-sparing operations do not seem justified in patients with invasive BAC.  相似文献   
965.
灾难的时代错误:灾害医学的过去、现在和将来(一)   总被引:1,自引:0,他引:1  
灾难,特别是地震、火山、洪水以及与战争有关的事件如饥饿和流行性传染病,是人类有记录的经历的一部分。从意大利庞贝的火山爆发,到约翰斯顿的洪水、第二次世界大战和黑色瘟疫,到西班牙流感,都发生了灾难,这不会被传说和历史书籍长期忘却。不过,在20世纪中叶以前,那些灾难的发生相对较少,且相距时间较长。从20世纪中叶以来,灾难的本质发生了变化。从恐怖分子使用“新技术”,到与气候有关的导致亿万美元经济损失的事件,表明这个世界正在发生变化。仅仅在最近的50~60年间,造成多种多样的伤亡事件,其危险性和频率的增加引人注目,并且注定要在接…  相似文献   
966.
967.
968.
969.
The aim of the present study was to explore differences in the clinical expression, clinical diagnoses and management of airway diseases in a primary-care setting. Patients aged >or=35 yrs who had ever smoked were enrolled when they presented for any reason to one of eight rural primary-care practices. Respiratory symptom questionnaires and spirometry were administered. In total, 1,034 patients had acceptable and reproducible spirometry, of whom 550 (53%) were males and 484 (47%) were females. Males smoked more than females (41.2 versus 29.2 pack-yrs) respectively, and were more likely to have a pre-bronchodilator forced expiratory volume in one second/forced vital capacity <0.70 at 22.4 versus 11.8%, respectively. However, more females than males reported breathlessness (51.0 versus 42.8%, respectively), a prior diagnosis compatible with airflow obstruction and taking respiratory medications (23.4 versus 14.9%, respectively). In conclusion, the current results suggest that females are more likely than males to report breathlessness and be prescribed respiratory medications independent of differences in the severity of airflow obstruction.  相似文献   
970.
There are no data available combining transbronchial needle aspiration (TBNA) of mediastinal lymph nodes and positron emission tomography (PET) in the staging of nonsmall cell lung cancer (NSCLC). The aim of the current study was to determine if these two methods can enhance the negative predictive value of the individual modality alone, for a specific lymph node station, and if this integrated approach can reduce the number of mediastinoscopies. A total of 113 patients with enlarged mediastinal lymph nodes (> or = 1 cm), who underwent both TBNA and PET scanning, were included. In 51 patients, histopathology, confirmed by surgical lymph node dissection, was compared with PET results and TBNA. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy to detect malignant lymphadenopathy was 68 (13/19), 89 (119/134), 46 (13/28), 95 (119/125) and 86% (132/152) for PET, respectively; 54% (6/11), 100 (53/53), 100 (6/6), 91 (53/58) and 92% (59/64), respectively for TBNA; and 100 (11/11), 94 (50/53), 79 (11/14), 100 (50/50) and 95 (61/64) for combined TBNA and PET, respectively. Combination of transbronchial needle aspiration and positron emission tomography has the potential to allow adequate mediastinal staging of nonsmall cell lung cancer with enlarged lymph nodes in most patients without the need for mediastinoscopy.  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