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   21087篇
  免费   1276篇
  国内免费   141篇
耳鼻咽喉   171篇
儿科学   516篇
妇产科学   394篇
基础医学   2445篇
口腔科学   805篇
临床医学   2029篇
内科学   4414篇
皮肤病学   421篇
神经病学   1299篇
特种医学   477篇
外国民族医学   5篇
外科学   2871篇
综合类   654篇
一般理论   15篇
预防医学   1802篇
眼科学   838篇
药学   1921篇
中国医学   227篇
肿瘤学   1200篇
  2024年   32篇
  2023年   283篇
  2022年   760篇
  2021年   1191篇
  2020年   790篇
  2019年   926篇
  2018年   1097篇
  2017年   772篇
  2016年   835篇
  2015年   849篇
  2014年   1118篇
  2013年   1325篇
  2012年   1847篇
  2011年   1864篇
  2010年   1117篇
  2009年   845篇
  2008年   1236篇
  2007年   1112篇
  2006年   954篇
  2005年   815篇
  2004年   659篇
  2003年   556篇
  2002年   468篇
  2001年   110篇
  2000年   119篇
  1999年   111篇
  1998年   75篇
  1997年   57篇
  1996年   58篇
  1995年   39篇
  1994年   29篇
  1993年   34篇
  1992年   34篇
  1991年   30篇
  1990年   24篇
  1989年   34篇
  1988年   27篇
  1987年   17篇
  1986年   22篇
  1985年   17篇
  1984年   26篇
  1983年   21篇
  1982年   17篇
  1981年   11篇
  1980年   13篇
  1979年   15篇
  1978年   12篇
  1976年   14篇
  1974年   11篇
  1973年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Despite the controversy of airway responsiveness to beta2-agonist drugs in asthma, in a previous study we showed increased responsiveness of asthmatic airways to isoprenaline. Therefore, in the present study of airway sensitivity to other beta2-agonists, salbutamol and its relationship to histamine responsiveness was reexamined. The threshold bronchodilator concentrations of inhaled salbutamol required for a 20% increase in forced expiratory flow in 1 sec (FEV1), (PC20) was measured in 20 normal and 19 asthmatic adults. Airway responsiveness to histamine, as the concentration that caused a 20% decrease in FEV1, was also measured in 11 normal and 12 asthmatic subjects; and the correlation between PC20 salbutamol and PC20 histamine was evaluated. Sensitivity to salbutamol was greater in asthmatics (PC20 = 7.24 mg/L) than in non-asthmatics (PC20 = 124.25 mg/L, p < 0.001). Airway responsiveness to histamine in asthmatics (PC20 = 0.18 g/L) was also significantly greater than in normal subjects (PC20 = 19.46 g/L, p < 0.001). There was a significant correlation between PC20 salbutamol and histamine (Rs = 0.6052, p < 0.005). Maximum response to both salbutamol and histamine and slope of concentration-response curves of both agents were significantly greater in patients with asthma than in normal subjects (p < 0.001 and p < 0.005 for maximum response and slope, respectively). The increased sensitivity of asthmatics to inhaled salbutamol suggests that they also may be more sensitive to their endogenous adrenaline, which may thus dilate and stabilize their airways.  相似文献   
22.
Duane retraction syndrome has been reported in association with structural abnormalities of the eye, including epibulbar dermoid, keratoconus, iris dysplasia, heterochromia iridis, persistent fetal vasculature, cataract, choroidal coloboma, microphthalmia, and optic nerve dysplasia. A novel association, that of bilateral Duane syndrome with bilateral aniridia, is the subject of this report.  相似文献   
23.

Background  

Different interventions can reduce the burden of the chronic low back pain. One example is the use of a 'Back School Programme'. This is a brief therapy that uses a health education method to empower participants through a procedure of assessment, education and skill development. This study aimed to evaluate to what extent the programme could improve quality of life in those who suffer from the condition.  相似文献   
24.
Long-term clinical and functional outcomes for patients undergoing foot and ankle amputations are not well documented. We attempted to document long-term outcomes for patients who required lower extremity amputations as a result of wounds suffered during wartime. For this study, 27 Iranian soldiers who had wounds requiring amputation of the foot and ankle were selected for follow-up. The participants' wartime medical records were reviewed, a clinical examination was performed, and each participant completed a questionnaire. Postamputation follow-up averaged 17.5 years. The most prevalent (66.6%) cause of injury was a land mine. The prevalences of different clinical symptoms reported by the amputees at the time of the last follow-up were as follows: 11 (40.7%) with phantom sensation, 6 (22.2%) with phantom pain, 12 (44.4%) with stump pain, 12 (44.4%) with back pain, 9 (33.3%) with contralateral knee pain, and 4 (14.8%) with ipsilateral knee pain; 20 (74%) reported treatment for psychological conditions. In regard to social conditions, 13 (48.1) were currently employed, or had been employed, for a number of years after the amputation; 26 (96%) had children, and all of the patients were married. The results of this observational study indicate that individuals have significant long-term pain and discomfort after war-related lower extremity amputation. Although all 27 (100%) of the amputees were able to maintain satisfactory family functioning, only 13 (48.1%) of the study participants were able to remain productively employed after undergoing amputation, and 20 (74%) reported long-term psychological problems in addition to their physical pain.  相似文献   
25.
Genetically modified mice offer a wide range of possibilities in preclinical drug discovery, e.g. for use in target identification, target validation and disease model generation. However, genomic modification and alteration in gene expression may cause unpredicted phenotypic alterations in the organism other than the intended ones. The aim of this study was to determine the importance of establishing the phenotype of transgenic and knockout mice models for use in pharmaceutical research.

A total number of 51 mouse models (transgenic and knockout) produced at AstraZeneca during a 4 year period were subjected to a thorough phenotyping package covering clinical as well as morphological aspects. Phenotype abnormalities were recorded in 36 (70.6%) of the mouse models. The majority of findings were considered to be minor in magnitude. Histopathological changes related to the genotype of the animals were observed in 33% of the mouse models, underlining the importance of pathology in the phenotyping program.  相似文献   

26.
The clinical patterns and predictors of cytomegalovirus (CMV) disease in kidney and/or pancreas transplant patients on ganciclovir (1.0 g po t.i.d.) or valganciclovir (450 mg po q.d.) prophylaxis were studied. This is a retrospective analysis of 129 transplant recipients. Median follow up was 12 months (range, 6-18 months). The overall incidence of CMV disease at 1-year post-transplant was 14% (4% tissue-invasive, 10% noninvasive). Seventeen of 18 patients were diagnosed with CMV after completion of 3 months' prophylaxis (median 8 weeks, range, 2-28 weeks). Induction treatment with thymoglobulin, and Donor +/Recipient - CMV status were the strongest predictors for the development of CMV disease. Cytomegalovirus incidence was not different between patients treated with ganciclovir or valganciclovir (15 vs. 17%, respectively). Valganciclovir (450 mg q.d.) is as effective as oral ganciclovir in CMV prophylaxis. High-risk individuals might require higher doses or longer duration of valganciclovir treatment.  相似文献   
27.
BACKGROUND: We hypothesized that major co-morbidities affect survival and complications after gastric bypass. METHODS: A total of 1465 patients undergoing laparoscopic and open gastric bypass between 1995 and 2002 were studied. Patients with a body mass index >or= 35 kg/m(2) and major co-morbidities (group 1, n = 1045) were compared with patients with a body mass index >or= 40 kg/m(2) with minor/no co-morbidities (group 2, n = 420). RESULTS: Group 1 patients were older (43 versus 36 years, P < 0.001) and had a greater BMI (53 versus 50 kg/m(2), P < 0.001). Early postoperative complications were greater in group 1 than in group 2 and included leaks (4.1% versus 1.2%, P < 0.0032) and wound infections (3.9% versus 1.4%, P < 0.0133). Procedure-related mortality in the series was 1.7%. Mortality was 10-fold greater in group 1 (2.3% versus 0.2%, P < 0.0032). The incidence of small bowel obstruction, incisional hernia, and pulmonary embolism was similar in the two groups. Excess weight loss was significantly greater in group 2 (68% versus 62%, P < 0.001) at 1 year. Resolution of group 1 co-morbidities was great, including hypertension in 62%, diabetes in 75%, venous stasis disease in 96%, and pseudotumor cerebri in 98%. CONCLUSION: Outcomes analysis of obesity surgery requires risk stratification. The very low mortality rates in published studies are likely explained by surgical treatment of low-risk patients with minor co-morbidities, such as those seen in group 2. However, despite the increased perioperative risk, the group 1 patients (with major co-morbidities) demonstrated dramatic resolution of their co-morbid conditions, justifying the decision to go forward with surgery. The data support a radical change in treatment philosophy in which morbidly obese individuals should be offered bariatric surgery before major co-morbid conditions develop as a strategy to decrease the operative risk.  相似文献   
28.
Cystic echinococcosis in Central Saudi Arabia: A 5-year experience.   总被引:1,自引:0,他引:1  
Background/aims: In this series of patients we aim to describe aspects of presentation, diagnosis and management of patients suffering from Echinococcosis in an endemic region. Methods: This is an observational study done at Riyadh Medical Complex, Saudi Arabia from 1999 to 2004. All adult patients admitted with the primary or incidental diagnosis of echinococcosis were included. These patients were followed up for 6 months. Data relating to patients' demographic characteristics, mode and duration of presentation, investigations, complications and treatment offered was collected. This data was then analyzed using SPSS 11.0. Result: 117 patients with a mean age of 40.9+/-20.7 years were admitted, male to female ratio being 1.7:1. 114 (97.4%) originated from Middle East which is an endemic area. Pain right upper quadrant (RUQ), followed by cough were the commonest symptoms. Nine patients presented with jaundice +/- choleangitis: 3 patients had intrabiliary rupture of the hydatid cyst, while 6 had extrinsic compression. Six patients had infected cyst. Fourteen patients had intrabronchial rupture diagnosed on bronchoscopy. Twenty five (21.4%) patients presented with recurrent disease. The Haemagglutination Inhibition test gave a sensitivity of 78.6. All cysts were visualized using USG, CXR and CT scan. Endocystectomy was the most frequent procedure. Post op 8 patients had biliary leakage and 3 had bronchopleural fistula a majority of whom settled conservatively while two required ERCP and one patient with bronchopleural fistula required surgery. Fifteen patients had infection related complications. During our follow up period no recurrences were recorded. All patients undergoing surgery also received medical treatment. Twenty five patients (21.4%) were unable to undergo operative treatment due to multiple reasons. They were medically treated. Conclusion: Cystic Echinococcosis is a disease of the middle aged. Ultrasonogram combined with a serological assay is the best diagnostic tool available for abdominal echinococcosis allowing diagnosis and staging, while chest X ray is the best screen for the pulmonary disease. The recommended treatment is endocystectomy with antihelmenthic therapy. But the problem of early detection of echinococcosis in endemic areas needs attention by workers as this approach can potentially prevent the devastating complications due to this disease.  相似文献   
29.
OBJECTIVE: The wisdom of surgery facing multiple and multi-focal ribs fractures (flail segment) remains controversial. By the present retrospective study, we sought to determine the advisability of surgery as well as the anatomical and biomechanical features of flail segment leading to secondary dislocation. METHOD: From 1970 to 2000, 127 patients underwent flail segment osteosynthesis. Clinical charts, operative reports and imaging data were reviewed retrospectively. Rib osteosynthesis was carried out with Judet staple and Kirschner wires until 1980, since then it has been undertaken with sliding-staples-struts. Postoperative chest X-ray was carried out to classify the flail segments into anterolateral and posterolateral types according to the location of anterior and posterior rib fractures. Each type was then divided into three subgroups of primary parietal, secondary parietal and retreat indications that were inferred retrospectively from final indications of rib osteosynthesis. RESULTS: The mean age of patients (ranging in age from 20 to 84 years) was 56+/-14.4 years with a male predominance (108/19). Seventy percent of flail segments was considered as posterolateral. The mean number of rib fractures per patient was 6+/-0.35. Rib osteosynthesis was undertaken with sliding-staples-struts in 70% of patients. The overall hospital mortality was 16%; it was subsequently reduced to 8% since sliding-staples-struts were used. The mean duration of ventilation was reduced from 5.8+/-0.76 days to 2.98+/-0.83 days with sliding-staples-struts. Seventy-seven percent of patients with posterolateral flail segment and primary parietal indication were extubated within the first 48 h postoperatively, whereas 46% of patients from other subgroups required ventilation for more than 5 days. Similarly, 83% of patients of the former subgroup returned to full previous level of activity compared with a rate of 52% for the latter subgroups. The flail segments were dislocated superoposteriorly for both anterolateral and posterolateral types, evoking the action of anterior serratus muscle. CONCLUSIONS: The anterolateral and posterolateral flail segments are rendered susceptible to secondary dislocation through a complex set of factors, of which the action of anterior serratus muscle is obvious. Restoration of parietal mechanics by early surgical reduction/fixation is a reliable therapeutic option in selected patients and offers encouraging results.  相似文献   
30.
BACKGROUND: Hemangioma is the most common tumor of infancy. Although it has a basically benign nature and usually spontaneously regresses, a small percentage (5%) have complications that need treatment. Many different therapeutic modalities can be used in this tumor. OBJECTIVE: To investigate the effect of a new method of treatment (intralesional bleomycin injection) in complicated hemangiomas. MATERIALS AND METHODS: In the Department of Radiation Oncology at Nemazee Hospital in Shiraz, Iran, from April 1992 to October 1998, 32 patients with complicated hemangioma were treated with four to six courses of direct injection of bleomycin into the lesion. RESULTS: After a minimum follow-up of 6 years, there was 70 to 100% regression in 18 patients, 50 to 70% in 7 cases, and less than 50% reduction in 7 patients. CONCLUSION: Intralesional injection of bleomycin is an easy, safe, and effective therapeutic modality in complicated cutaneous hemangiomas.  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