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   8791篇
  免费   545篇
  国内免费   57篇
耳鼻咽喉   61篇
儿科学   201篇
妇产科学   122篇
基础医学   828篇
口腔科学   173篇
临床医学   786篇
内科学   2257篇
皮肤病学   80篇
神经病学   1185篇
特种医学   290篇
外科学   1576篇
综合类   21篇
一般理论   1篇
预防医学   361篇
眼科学   209篇
药学   462篇
中国医学   13篇
肿瘤学   767篇
  2024年   9篇
  2023年   124篇
  2022年   208篇
  2021年   396篇
  2020年   230篇
  2019年   303篇
  2018年   313篇
  2017年   237篇
  2016年   272篇
  2015年   285篇
  2014年   412篇
  2013年   497篇
  2012年   766篇
  2011年   713篇
  2010年   364篇
  2009年   364篇
  2008年   545篇
  2007年   530篇
  2006年   547篇
  2005年   451篇
  2004年   410篇
  2003年   360篇
  2002年   310篇
  2001年   63篇
  2000年   53篇
  1999年   62篇
  1998年   41篇
  1997年   39篇
  1996年   47篇
  1995年   28篇
  1994年   34篇
  1993年   30篇
  1992年   40篇
  1991年   39篇
  1990年   21篇
  1989年   35篇
  1988年   19篇
  1987年   15篇
  1986年   20篇
  1985年   17篇
  1984年   27篇
  1983年   17篇
  1982年   13篇
  1981年   17篇
  1980年   8篇
  1979年   12篇
  1977年   5篇
  1975年   5篇
  1974年   10篇
  1973年   5篇
排序方式: 共有9393条查询结果,搜索用时 15 毫秒
81.

Background

Sentinel lymph node biopsy (SLNB) allows for staging of the axillary node status in early-stage breast cancer (BC) patients and avoiding complete axillary lymph node dissection (ALND) when the sentinel lymph node (SLN) is proven to be free of disease. In a previous randomized trial we compared SLNB followed by ALND (ALND arm) with SLNB followed by ALND only if the SLN presented metastasis (SLNB arm). At a mid-term of ≈ 6 years median follow-up, the two strategies appeared to ensure similar survival and locoregional control. We have revised these previous findings and update the results following a 15-year observation period.

Methods

Patients were randomly assigned to either the ALND or SLNB arm. The main endpoints were event-free survival (EFS), overall survival (OS), and axillary disease recurrence. EFS and OS were assessed using Kaplan–Meier analysis and the log-rank test.

Results

The ALND and SLNB arms included 115 and 110 patients, respectively. At 14.3 years median follow-up, 39 primary BC-related recurrences occurred, 22 (19 %) of which occurred in the ALND arm and 17 (16 %) occurred in the SLNB arm (p = 0.519). No axillary relapse developed in the SLNB arm, while two were observed in the ALND arm. OS (82.0 vs. 78.8 %) and EFS (72.8 vs. 72.9 %) were not statistically different between the ALND and SLNB arms (p = 0.502 and 0.953, respectively).

Conclusions

SLNB is a safe and efficacious component of the surgical treatment of early-stage BC patients. In the long-term, SLNB is equivalent to ALND in terms of locoregional nodal disease control and survival in this subset of patients.
  相似文献   
82.
Background  Viscosupplementation, with hyaluronan derivates injected into the intra-space of osteoarthritic joints, is now widely used for the treatment of knee osteoarthritis. This study evaluates the results in terms of pain and disability of intra-articular injections of hyaluronan derivates into the ankle joint in patients suffering from grade II primary or secondary osteoarthritis of the ankle. Methods  Twenty-one patients with a painful ankle and radiographic evidence of grade II osteoarthritis had three weekly intra-articular injections of 2 ml of hylan G-F 20 (10 mg/ml) into the ankle joint. The primary clinical outcome measurement was the ankle osteoarthritis score (AOS) at the baseline, and at 6, 12 and 18 months. Results  Significant improvement of the AOS from baseline was seen after 6 months (p=0.0001). This improvement was maintained over time with no further changes at 12- and 18-month follow-ups. Regarding pain, the AOS improved over time from the baseline to the 18-month follow up and became statistically significant at the 12- and 18-month follow-ups (p<0.05).  相似文献   
83.
84.
Laparoscopic Heller myotomy (LHM) has become the standard treatment option for achalasia. The incidence of esophageal perforation reported is about 5%–10%. Robotically assisted Heller myotomy (RAHM) is emerging as a safe alternative to LHM. Data comparing the two approaches are scant. The aim of this study was to compare RAHM with LHM in terms of efficacy and safety for treatment of achalasia. A total of 121 patients underwent surgical treatment of achalasia at three institutions. A retrospective review of prospectively collected perioperative data was performed. Patients were divided into two groups: group A (RAHM), 59 patients, and group B (LHM), 62 patients. All the operations were completed using minimally invasive techniques. There were 63 women and 58 men, with a mean age of 45 ±19 years (14–82 years). Fifty-one percent of patients in group A and 95% of patients in group B reported weight loss. Duration of symptoms was equal for both groups. Dysphagia was the main complaint in both groups (P = NS). There was no difference in preoperative endoscopic treatment in both groups (44% versus 27%, P = NS). Operative time was significantly shorter for LHM in the first half of the experience (141 ± 49 versus 122 ± 44 minutes, P < .05). However, in the last 30 cases there was no difference in operative time between the groups (P = NS). Intraoperative complications (esophageal perforation) were more frequent in group B (16% versus 0%). The incidence of postoperative heartburn did not differ by group. There were no deaths. At 18 and 22 months, 92% and 90% of patients had relief of their dysphagia. This study suggests that RAHM is safer than LHM, because it decreases the incidence of esophageal perforation to 0%, even in patients who had previous treatment. At short-term follow-up, relief of dysphagia was equally achieved in both groups. Presented at the Forty-Sixth Annual Meeting of The Society for Surgery of the Alimentary Tract, Chicago, Illinois, May 14–18, 2005 (oral presentation). This study was supported in part by a grant provided by Intuitive Surgical, Inc. and Ethicon Endo-Surgery, Inc.  相似文献   
85.
BACKGROUND CONTEXT: Computerized frameless stereotactic image-guidance has been used in recent years to improve the accuracy and safety of pedicle screw placement during spine surgery. Because the possibility of intervertebral motion exists, and because the patient is usually in a different position when preoperative imaging is performed compared with the operative position, it has been suggested that the imaging model of the complete lumbar spine and the surgically exposed lumbar spine may be significantly discordant. Consequently, current protocols suggest registering each spinal level (single-level registration) separately before pedicle screw placement at that level, a time-consuming process. PURPOSE: To assess the accuracy of single-time multilevel registration for multilevel pedicle screw placement during image-guided, computer-assisted spine surgery, in the setting of degenerative disorders of the lumbar spine. STUDY DESIGN/SETTING: This is a prospective clinical and radiological study of 45 patients with degenerative disorders of the lumbar spine who underwent instrumented fusion with the use of single-time multilevel registration computer-assisted, image-guided tomography. The accuracy of the pedicle screws placement was confirmed on the basis of a protocol that included intraoperative spontaneous electromyographic (EMG) recordings, direct pedicle visualization, and computer tomography (CT) scans when clinically indicated during the follow-up period. PATIENT SAMPLE: Forty-five consecutive patients who fulfilled the criteria of computer-assisted, image-guided tomography pedicle screw placement for degenerative lumbar spine disease without overt instability. OUTCOME MEASURES: The principal outcome measure was the accuracy of pedicle screw placement with single-time multilevel registration for multilevel pedicle screw placement during image-guided, computer-assisted spine surgery; postoperative CT performed for clinical indications during the follow-up course was used for the assessment of pedicle screw placement. METHODS: Patients were assessed clinically before and after the operation. Data from 45 consecutive cases of image-guided, computer-assisted lumbar spinal fusion were statistically analyzed to determine the relationship between the number of levels registered during single-time registry and the mean registration error (MRE). Intraoperative spontaneous EMG, direct visualization, and postoperative CT scans were used to assess the accuracy of pedicle screw insertion. RESULTS: None of the patients involved in this study experienced clinical sequelae of improper pedicle screw placement. MREs after surface mapping and after point merge were small (less than 1.00 mm and less than 3.00 mm, respectively). During the intraoperative assessment of the pedicle screws placement, no significant spontaneous EMG activity was recorded and the pedicular walls were found intact in direct visualization. The postoperative CT scans showed in 10 patients accurate placement in 55 of the 57 pedicle screws with expansion of the medial wall in two screws. CONCLUSIONS: Single-time, multilevel registration may decrease operative time relative to repeated, single-level registrations, without compromising the increased accuracy of pedicle screw placement afforded by this technique in the setting of degenerative disorders of the lumbar spine. Despite the advantages in computer-guided image surgery, cautious application in the individual patient is recommended until more comprehensive data can be gathered in specific degenerative pathology with overt instability; thus the knowledge of the anatomy remains crucial.  相似文献   
86.
New immunosuppressive agents and regimens should be evaluated specifically in living donor liver transplant patients due to potential clinical and pharmacokinetic differences between deceased donor and living donor transplant recipients. The analysis presented here is the first direct comparison of clinical outcomes using cyclosporine microemulsion (CsA-ME) with monitoring of blood concentration at 2 hours postdose (C2) and tacrolimus-based immunosuppression in living donor liver transplantation. The analysis was conducted on the data provided by the 39 recipients of a living donor transplant out of the 495 patients enrolled in a 6-month, randomized, prospective, multicenter, open-label study (LIS2T). Patients were randomized to CsA-ME (C2 monitoring) or tacrolimus (monitoring of predose trough drug blood level [C0)]) and were administered corticosteroids with or without azathioprine. Twenty-three living-donor patients received CsA-ME and 16 received tacrolimus. By month 6, 9% of patients receiving CsA-ME and 19% of those receiving tacrolimus had lost their graft or died (not significant [NS]). Nine episodes of biopsy-proven acute rejection were reported: 4 in the CsA-ME group (17%) and 5 in the tacrolimus cohort (31%, NS). There were no significant differences in any safety parameter between groups. The most frequently reported serious adverse events were infections, which occurred in 14 patients in the CsA-ME group (61%) and 13 patients in the tacrolimus arm (81%, NS). Twelve patients in the CsA-ME arm (52%) and 5 in the tacrolimus arm (31%, NS) discontinued the study prematurely. In conclusion, CsA-ME C2 monitoring or tacrolimus both offer effective protection against rejection in living donor liver transplants while maintaining a good safety profile.  相似文献   
87.
Target organs express antigens directly recognized by antigen-specific T cells, thereby precipitating rejection. When early T-cell activation is inhibited, there is a low risk of rejection. We sought to determine the predictive values of serial posttransplant blood cyclosporine trough (C(0)) concentrations to minimize the risk for a first rejection episode compared with 2-hour postdose (C(2)) drug concentrations. The final aim of the study was to identify a concentration range for the best predictive pharmacokinetic parameter that should be targeted to reduce the risk of rejection. This possibility was explored in 334 de novo kidney transplant recipients who participated in the prospective, multicenter Mycophenolate Steroid-Sparing Trial. Among measurements performed during the first 6 months postsurgery, cyclosporine C(0) levels measured early after transplantation were the strongest predictor of acute graft rejection. Levels within 300 to 440 ng/mL were associated with the lowest risk of rejection, while patients with levels lower than 300 ng/mL showed a more than double risk. Cyclosporine trough values predicted allograft rejection with an accuracy of 74%, while C(2) levels had no predictive value. These findings underline the need to target cyclosporine therapy early posttransplant to modulate T-cell activation.  相似文献   
88.
All patients undergoing heart surgery experience a certain amount of nonspecific myocardial injury documented by the release of cardiac biomarkers and associated with poor outcome. We investigated the role of unipolar radiofrequency ablation of atrial fibrillation on the release of cardiac biomarkers in 71 patients undergoing mitral valve surgery and concomitant left atrial ablation case-matched with 71 patients undergoing isolated mitral surgery. The study was powered to detect a 3 ng/mL difference. There was no difference between the 2 groups in terms of cardiac troponin I (10 +/- 5.3 versus 12 + 10.4 ng/mL; P = 0.7) or creatine kinase-MB (50 +/- 21.8 versus 57 +/- 62.0 ng/mL; P = 0.5) release. Postoperative peak cardiac troponin I levels had univariate associations with the duration of cardiopulmonary bypass (P = 0.002) and aortic cross-clamping (P = 0.001) and with the surgical technique (15 +/- 12 ng/mL for mitral valve replacement versus 9 +/- 4.8 for mitral valve repair; P = 0.0007) at univariate analysis. Mitral valve replacement was the only independent predictor of postoperative peak release of cardiac troponin I identified with multivariate analysis (P = 0.005). Radiofrequency ablation of atrial fibrillation does not significantly increase cardiac biomarker release compared with isolated mitral surgery; mitral valve repair is associated with less release of cardiac biomarkers compared with mitral valve replacement.  相似文献   
89.
90.

Introduction

Pirfenidone was the first antifibrotic drug approved in Argentina for idiopathic pulmonary fibrosis (IPF). Outcomes in real life may differ from the results of clinical trials. The primary endpoint was to study the tolerance of pirfenidone in real life. Secondary endpoints were to analyze effectiveness and reasons for discontinuation.

Materials and methods

Retrospective observational study conducted in four specialized centers in Argentina. We analyzed the medical records of patients with IPF who received pirfenidone between June 2013 and September 2016. Adverse events (AE) and the variables that could influence these results were analyzed. Forced vital capacity (FVC%) parameters were also compared between the pre-pirfenidone and post-pirfenidone periods.

Results

Fifty patients were included, 38 (76%) men, with mean age (SD) 67.8 (8.36) years. Mean (SD) exposure to pirfenidone was 645.68 (428.19) days, with a mean daily dose (SD) of 2064.56 mg (301.49). Nineteen AEs in 15 patients (30%) were reported: nausea (14%), asthenia (10%) and skin rash (8%). A total of 18 patients (36%) interrupted treatment, only 1 definitively. The most frequent reason for discontinuation was failure of suppliers to provide the drug (9 subjects; 18%). We compared the evolution of FVC% between the pre-pirfenidone and post-pirfenidone periods, and found a mean (SD) FVC% decline of 4.03% (7.63) pre-pirfenidone and 2.64% (7.1) post-pirfenidone (P=.534).

Conclusions

In our study, pirfenidone was well tolerated and associated with a reduction in FVC decline, although without reaching statistical significance.  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