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   1485篇
  免费   95篇
  国内免费   12篇
耳鼻咽喉   13篇
儿科学   40篇
妇产科学   26篇
基础医学   107篇
口腔科学   100篇
临床医学   144篇
内科学   373篇
皮肤病学   27篇
神经病学   103篇
特种医学   72篇
外科学   328篇
综合类   32篇
预防医学   51篇
眼科学   26篇
药学   65篇
中国医学   5篇
肿瘤学   80篇
  2024年   2篇
  2023年   24篇
  2022年   73篇
  2021年   98篇
  2020年   57篇
  2019年   81篇
  2018年   97篇
  2017年   60篇
  2016年   72篇
  2015年   71篇
  2014年   87篇
  2013年   98篇
  2012年   135篇
  2011年   121篇
  2010年   64篇
  2009年   57篇
  2008年   84篇
  2007年   76篇
  2006年   61篇
  2005年   47篇
  2004年   28篇
  2003年   28篇
  2002年   29篇
  2001年   6篇
  2000年   5篇
  1999年   5篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1995年   2篇
  1992年   2篇
  1991年   5篇
  1990年   1篇
  1989年   3篇
  1988年   4篇
  1987年   2篇
  1985年   1篇
  1979年   1篇
排序方式: 共有1592条查询结果,搜索用时 15 毫秒
101.
Background  The management of symptomatic or incidentally discovered common bile duct (CBD) stones is still controversial. Of patients undergoing elective cholecystectomy for symptomatic cholelithiasis, 5–15% will also harbor CBD stones, and those with symptoms suggestive of choledocholithiasis will have an even higher incidence. Options for treatment include preoperative endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy (ERCP/ES) followed by laparoscopic cholecystectomy, laparoscopic cholecystectomy with intraoperative cholangiogram (LC/IOC), followed by either laparoscopic common bile duct exploration (LCBDE) or placement of a common bile duct double-lumen catheter with postoperative management. The purpose of this analysis was to determine the optimal management of such patients. Methods  A decision analysis was performed to analyze the management of patients with suspected common bile duct stones. The basic choice was between preoperative ERCP/ES followed by LC, LC/IOC followed by LCBDE, or common duct double-lumen catheter (Fitzgibbons tube) placement with either expectant management or postoperative ERCP/ES. Data on morbidity and mortality was obtained from the literature. Sensitivity analysis was done varying the incidence of positive CBD stones on IOC with associated morbidity and mortality. Results  One-stage management of symptomatic CBD stones with LC/LCBDE is associated with less morbidity and mortality (7% and 0.19%) than two-stage management utilizing preoperative ERCP/ES (13.5% and 0.5%). Sensitivity analysis shows that there is an increase in morbidity and mortality for LC/LCBDE as the incidence of positive IOC increases but are still less than two-stage management even with a 100% positive IOC (9.4%, 0.5%). If a double-lumen catheter is to be used for positive IOC, the morbidity would be higher than two-stage management only if the positive IOC incidence is more than 65% but still with no mortality. Conclusion  LCBDE has lower morbidity and mortality rates compared to preoperative ERCP/ES in the management of patients with suspected CBD stones even if the chance of CBD stones reaches 100%. Using a common duct double-lumen catheter may be considered if LCBDE is not feasible and the chance of CBD stone is less than 65%. Presented in part at the 49th Annual Meeting of the Society for Surgery of the Alimentary Tract [Poster Session], San Diego, CA, May 17–21, 2008  相似文献   
102.
High-risk human papillomavirus (HPV) E6 and E7 oncoproteins are essential factors for HPV-induced carcinogenesis, and for the maintenance of the consequent neoplastic growth. Cellular transformation is achieved by complex interaction of these oncogenes with several cellular factors of cell cycle regulation including p53, Rb, cyclin-CDK complexes, p21 and p27. Both persistent infection with high-risk HPV genotypes and immune dysregulation are associated with increased risk of HPV-induced squamous cell carcinoma.  相似文献   
103.
104.
Purpose. To compare clinical advantages and hemodynamic and respiratory changes during one lung-collapsed ventilation (OLCV) using a double-lumen tube (DLT) or a single-lumen tube (SLT) with intrathoracic CO2 insufflation, in patients undergoing thoracic sympathectomy (TS) under general anesthesia. Methods. One hundred and twenty-five patients (94 men and 31 women) undergoing TS for the treatment of palmar hyperhidrosis (PH) were randomly allocated to two groups: group A (68 patients; age, 29 ± 6 years) in whom DLT was used, and group B (57 patients; age, 32 ± 3 years) in whom SLT with intrathoracic CO2 insufflation at a rate of 0.5–1 l·min−1 and sustained intrathoracic pressure at 6 mmHg insufflation were used. Anesthesia was maintained with 1 minimum alveolar concentration (MAC) isoflurane in 50% nitrous oxide in oxygen with incremental doses of sufentanil and atracurium when required. Arterial blood gases were measured in 10 patients in group B. Hemodynamic and respiratory parameters were obtained perioperatively. Results. There were no significant differences in hemodynamic and respiratory parameters between the two groups during the study phases, except for the arterial oxygen saturation (SpO2). The times required for anesthesia and surgery were significantly shorter in the SLT group than in the DLT group. SpO2 during OLCV was 95 ± 1% with DLT and 98 ± 1% with SLT, with a significant difference. Three patients had an SpO2 of less than 90% in the recovery room, where the chest tube position was readjusted, with no further sequelae. Conclusion. General anesthesia with SLT and intrathoracic CO2 insufflation provides optimal operating conditions, adequate oxygenation, and perfect hemodynamic stability during TS. Received: November 28, 2000 / Accepted: August 8, 2001  相似文献   
105.
BACKGROUND: TTP is a rare haematological disease consisting of thrombocytopenia, haemolytic anaemia, fever, neurological symptoms and renal failure. PATIENT: A 63-year-old female patient presented to our clinic with bilateral progressive loss of visual acuity accompanied by metamorphopsia. Ophthalmoscopy revealed pigmentepithelial choroidal atrophy secondary to the occlusion of chorioidal vessels and disseminated intraretinal and diffuse vitreal haemorrhage. Fluorescein angiography showed an obvious hyperfluorescence in the areas of choroidal atrophy as well as perivascular leakage. The patient had a history of TTP, as diagnosed by internal medicine. CONCLUSION: Vascular damage in TTP is due to disseminated hyalin clots of fibrin platelets which aggregate in the small capillaries, caused by a disorder of the endothelium-thrombocyte interaction. When evaluating patients with occlusion areas of the choriocapillaris, Moschcowitz's disease should be taken into consideration even in elderly patients.  相似文献   
106.
Acne treatment with a 1,450 nm wavelength laser and cryogen spray cooling   总被引:8,自引:0,他引:8  
BACKGROUND AND OBJECTIVES: A laser with a wavelength in the mid-IR range targeting the depth in skin where sebaceous glands are located in combination with cryogen spray cooling was evaluated for treatment of acne. In this non-ablative treatment, the laser energy heats the dermal volume encompassing sebaceous glands whereas the cold cryogen spray preserves the epidermis from thermal damage. STUDY DESIGN/MATERIALS AND METHODS: Monte Carlo simulations and heat transfer calculations were performed to optimize the heating and cooling parameters. A variety of heating and cooling parameters were tested in an in vivo rabbit ear study to evaluate the histological effect of the device on sebaceous glands and skin. Similar experiments were performed on ex vivo human skin. A clinical study for the treatment of acne on backs of human males was also conducted. RESULTS: Monte Carlo simulations and heat transfer calculations resulted in a thermal damage profile that showed epidermal preservation and peak damage in the upper dermis where sebaceous glands are located. Ex vivo human skin histology confirmed the damage profile qualitatively. In vivo rabbit ear histology studies indicated short-term thermal alteration of sebaceous glands with epidermal preservation. In the human clinical study on the back, a statistically significant reduction in lesion count on the treated side compared to the control side was seen (p < 0.001). Side effects were transient and few. CONCLUSIONS: The studies reported here demonstrate the feasibility of treating acne using a photothermal approach with a mid-IR laser and cryogen cooling.  相似文献   
107.
108.
Serum leptin and cholesterol levels in patients with bipolar disorder   总被引:1,自引:0,他引:1  
Low cholesterol levels have been reported in patients with manic episodes. Leptin seems to be strongly associated with lipid metabolism. In the present study, therefore, serum total cholesterol and leptin levels were compared in 16 patients with manic episodes, 16 with bipolar I disorder in full remission and 16 healthy controls. The serum total cholesterol and leptin levels were measured and Young Mania Rating (YMRS) and Hamilton Depression Rating Scales (HAM-D) were administered for each subject. Both the patients with manic episodes and the patients with bipolar I disorder in full remission had markedly low serum cholesterol and leptin levels compared with controls, though the difference was more obvious in patients with manic episodes. In addition, there were negative correlations between YMRS scores and serum cholesterol or leptin levels in the patients with manic episodes. Our results suggest that the patients with manic episodes and those with bipolar I disorder in full remission seem to be associated with decreased serum cholesterol and leptin levels.  相似文献   
109.
To examine the importance of free radicals in the pathogenesis of obsessive-compulsive disorder (OCD), we aimed to evaluate whether malondialdehyde (MDA), a product of lipid peroxidation, and antioxidant enzyme [superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT)] activity levels were associated with OCD. The patients were divided into two subgroups according to whether DSM-IV major depressive disorder (MDD) was accompanied (OCD + MDD) or not (OCD - MDD). The MDA and antioxidant enzyme levels both in patients and controls were determined. SOD activity levels were significantly higher in the OCD + MDD group compared with the control and the OCD - MDD group. Although the OCD - MDD group had slightly higher SOD activity levels as compared with the controls, the difference was not statistically significant. GSH-Px activity levels were statistically significantly higher in both groups compared with controls. Likewise, there was a significant difference in GSH-Px activity levels between the OCD + MDD and OCD - MDD group. CAT activity levels were slightly higher in the OCD + MDD group compared with the OCD - MDD and control group. MDA levels in both groups were significantly higher than in controls. In addition, the difference in MDA levels between both groups was statistically significant. In conclusion, our results suggest that OCD is associated with free radicals and that it may be a heterogeneous subtype including some biological indications of anxiety and affective disorders. More comprehensive and detailed studies are needed to decipher the exact role of free radicals in OCD.  相似文献   
110.
Sinus Valsalva aneurysm rupture (SVAR) is a rare cardiac abnormality that requires surgical correction when diagnosed. Previously, cardiac catheterization and angiography were thought to be necessary for its diagnosis. We present two pediatric cases of SVAR with subarterial ventricular septal defect (VSD) diagnosed noninvasively by echocardiography; surgical findings confirmed the diagnosis. In both of our cases the origin of SVAR was the right coronary sinus. The first case was ruptured into the right ventricular cavity; the second was ruptured into the right ventricular outflow tract. Continuous murmurs heard during follow-up of children with VSD must alert the physician to this pathology. Combined two-dimensional, Doppler and color-Doppler echocardiography is an accurate, noninvasive method for diagnosis of SVAR.  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