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   713篇
  免费   58篇
  国内免费   3篇
耳鼻咽喉   18篇
儿科学   19篇
妇产科学   7篇
基础医学   73篇
口腔科学   7篇
临床医学   69篇
内科学   178篇
皮肤病学   6篇
神经病学   33篇
特种医学   39篇
外科学   152篇
综合类   14篇
预防医学   36篇
眼科学   30篇
药学   47篇
中国医学   3篇
肿瘤学   43篇
  2023年   11篇
  2022年   22篇
  2021年   31篇
  2020年   36篇
  2019年   45篇
  2018年   37篇
  2017年   20篇
  2016年   18篇
  2015年   36篇
  2014年   33篇
  2013年   33篇
  2012年   64篇
  2011年   59篇
  2010年   51篇
  2009年   37篇
  2008年   40篇
  2007年   48篇
  2006年   37篇
  2005年   18篇
  2004年   24篇
  2003年   33篇
  2002年   16篇
  2001年   1篇
  2000年   4篇
  1999年   5篇
  1998年   6篇
  1997年   2篇
  1995年   1篇
  1992年   3篇
  1980年   2篇
  1973年   1篇
排序方式: 共有774条查询结果,搜索用时 15 毫秒
101.

Background

Seizures after cardiac surgery are a serious complication. The antifibrinolytic agent tranexamic acid (TA), which has known proconvulsant properties, may be associated with postoperative seizures. We sought to determine the association between TA and other risk factors for seizures after cardiac surgery.

Methods and results

We analyzed a database of consecutive cardiac surgery patients (April 2003 to December 2009) using multivariable logistic regression analysis to assess for seizure risk factors. Seizures occurred in 56 of 5,958 patients (0.94%). TA use was associated with an increased risk of seizures (odds ratio 7.4, 95% confidence interval 2.8?C19.3; P??20; preoperative cardiac arrest; preoperative neurological disease; open chamber surgery; cardiopulmonary bypass time?>?150?min; and previous cardiac surgery. Seizures occurred at a median of 5.3 hr (interquartile range 2.4?C15.1 hr) after the end of surgery. In all, 58.1% were grand mal, 14.5% were associated with a stroke, and 58.1% recurred in hospital. Altogether, 48.3% of the patients were able to discontinue anticonvulsant medications prior to discharge. Compared to the non-seizure group, seizure patients had an increased rate of postoperative neurological complications, defined as delirium and/or stroke (3.2% vs 19.6%, P?vs 4.7?days, P?<?0.001), and increased ICU mortality (1.4 % vs 9.7 %, P?=?0.001).

Conclusions

Our data suggest that multiple risk factors, including TA, are associated with seizures after cardiac surgery. Thus, the TA dose may be a readily modifiable risk factor for postoperative seizures.  相似文献   
102.
103.
Fast and reliable data acquisition is a major requirement for successful and useful biological electron paramagnetic resonance imaging (EPRI) experiments. Even a technologically advanced and professionally supervised EPRI system can exhibit instabilities initiated by perturbations such as animal motion, microphonics, and temperature changes. As a result, part of an acquired data set may become corrupted with excessive noise and distortions, which in turn may degrade the quality of the reconstructed image. In this work an automated scheme to monitor the system performance and stability over the course of an experiment is demonstrated. This method ensures that the quality of the acquired data is maintained during the experiment. For this purpose, four parameters including noise content and integration of each acquired projection are quantified and measured against those of the zero-gradient (ZG) projection, which is set as a quality benchmark. Projections with parameter values that differ substantially from the expected values are identified as damaged and consequently are reacquired. Therefore, the proposed technique not only effectively monitors the quality of acquisition, it also saves a substantial amount of acquisition time because it eliminates the necessity of repeating the entire experiment in cases in which only a small fraction of the data are corrupted.  相似文献   
104.
Pulmonary endothelial pavement patterns.   总被引:1,自引:0,他引:1       下载免费PDF全文
G Kibria  D Heath  P Smith    R Biggar 《Thorax》1980,35(3):186-191
The appearance of the endothelial pavement pattern was studied in the pulmonary trunk, pulmonary veins, aorta, and inferior vena cava of the rat by means of silver staining of the cell borders. The endothelial cell in each of the four blood vessels was found to have its own distinctive shape, fusiform and pointed in the direction of blood flow in the case of the aorta and larger and more rectangular in the pulmonary trunk and pulmonary veins. Detailed quantitation of the dimensions and surface area of the endothelial cells in each blood vessel was carried out by a photographic technique. Pulmonary hypertension was induced in one group of rats by feeding them on Crotalaria spectabilis seeds. The endothelial pavement pattern in their pulmonary trunks became disrupted with many of the cells assuming a fusiform shape reminiscent of aortic endothelium. Many small, new endothelial cells formed in the pulmonary trunk suggesting division of cells to line the enlarging blood vessels. In contrast the endothelial cells of the inferior vena cava merely increased in size to cope with the dilatation of this vein.  相似文献   
105.
106.
Burki T  Hamid R  Duffy P  Ransley P  Wilcox D  Mushtaq I 《The Journal of urology》2006,176(3):1138-41; discussion 1141-2
PURPOSE: The aim of this study was to determine whether redo bladder neck reconstruction is effective in achieving continence after a failed bladder neck reconstruction procedure. MATERIALS AND METHODS: We retrospectively reviewed the hospital records of patients with bladder exstrophy who had undergone redo bladder neck reconstruction. There were 30 patients in the study, including 20 boys and 10 girls. Mean patient age at redo bladder neck reconstruction was 9.3 years (range 3.2 to 15.5). The patients were divided into 3 groups on the basis of the preoperative pattern of incontinence--incomplete wetters, complete wetters and those on continuous suprapubic drainage. Of the patients 15 already had undergone bladder augmentation, 12 had undergone a Mitrofanoff procedure and 12 had been treated with bulking agents injected in the bladder neck in an attempt to achieve continence. Four patients had undergone more than 1 bladder neck procedure. The patients were investigated with a combination of noninvasive urodynamics, cystoscopy, cystogram and ultrasound. All patients underwent Mitchell's modification of Young-Dees-Leadbetter bladder neck reconstruction. Additional procedures performed included augmentation cystoplasty and Mitrofanoff formation. RESULTS: Mean followup was 6.9 years (range 1.2 to 15.5). Postoperatively 28 patients were using clean intermittent catheterization to empty the bladder (5 per urethra, 23 via Mitrofanoff). Two patients remained on continuous suprapubic catheter drainage. A total of 18 patients (60%) were dry postoperatively (80% of girls and 50% of boys). Among dry patients only 3 were performing clean intermittent catheterization per urethra and 15 via a Mitrofanoff channel. No patient was able to void per urethra without the need for clean intermittent catheterization. The 2 patients on continuous suprapubic catheter drainage continued to remain so. At night only 50% of the patients were dry (5 on free drainage, 4 on clean intermittent catheterization, 6 not on any drainage). Those patients who did not respond satisfactorily to redo bladder neck reconstruction underwent subsequent additional procedures, which included injection of bulking agents (3 patients), insertion of an artificial urinary sphincter (1), Mitrofanoff formation (2) and bladder augmentation plus Mitrofanoff channel (1). Postoperative complications included difficulty with clean intermittent catheterization (8 patients), perivesical leak (1), recurrent epididymo-orchitis (1), upper urinary tract dilatation (2) and incisional hernia (1). Bladder neck closure was being considered in 5 patients. CONCLUSIONS: In our experience redo bladder neck reconstruction cannot achieve continence with volitional voiding per urethra. Although redo bladder neck reconstruction can render a significant number of patients dry, it is only effective if performed in conjunction with augmentation. Failure of the initial bladder neck reconstruction may be a reflection of a bladder that is of inadequate capacity and/or compliance. Therefore, bladder augmentation should be considered in all patients requiring redo bladder neck reconstruction. Bladder neck closure may be a better alternative to redo bladder neck reconstruction.  相似文献   
107.
108.
The gallbladder specimens of patients who underwent cholecystectomy for symptomatic gallstones between 2003 and 2005 were evaluated for the presence of Intestinal Metaplasia. (IM) and its risk factors. IM was positive in 39% of 293 patients tested, and in the comparative analysis of 114 metaplasia positive versus 179 negative patients, a high risk was found in patients who were 60 years or older [adjusted odds ratio (aOR) = 3.0, 95% confidence interval (CI): 1.5, 6.2]. Other factors with aOR greater than 1 were moderate to excessive use of chilies (1.8) and ethnic origin of North India (1.7). Screening method has yet to be devised for early detection of gallbladder cancer by identifying metaplastic lesions early in life. We believe that large geographic variation and lifestyle environmental factors associated with the development of gallbladder metaplasia and cancer mortality are concealed in our study that needs to be further explored.  相似文献   
109.
Orbital cellulitis due to presumed gas-producing organisms has been associated with poor visual prognosis. We report successful visual recovery in a 14-year-old boy with orbital cellulitis and gas in the orbit on CT scan. The patient was treated with intravenous antibiotics and prompt orbital decompression. Pus from the sinus aspirate and orbital drain grew H. influenzae and Gram-negative bacilli. Repeat orbital surgery with drainage of residual abscess was performed and the patient made a complete recovery.  相似文献   
110.

Objective

To investigate the bioactivities of crude n-hexane, ethyl acetate and methanol extracts of aerial part of Boerhavia diffusa Linn. (B. diffusa) and its phytochemical analysis.

Methods

The identification of phytoconstituents and assay of antioxidant, thrombolytic, cytotoxic, antimicrobial activities were conducted using specific standard in vitro procedures.

Results

The results showed that the plant extracts were a rich source of phytoconstituents. Methanol extract showed higher antioxidant, thrombolytic activity and less cytotoxic activity than those of n-hexane and ethyl acetate extracts of B. diffusa. Among the bioactivities, antioxidant activity was the most notable compared to the positive control and thus could be a potential rich source of natural antioxidant. In case of antimicrobial screening, crude extracts of the plant showed remarkable antibacterial activity against tested microorganisms. All the extracts showed significant inhibitory activity against Candida albicuns, at a concentration of 1000 µg/disc.

Conclusions

The present findings suggest that, the plant widely available in Bangladesh, could be a prominent source of medicinally important natural compounds.  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