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   3124篇
  免费   290篇
  国内免费   90篇
耳鼻咽喉   35篇
儿科学   38篇
妇产科学   33篇
基础医学   361篇
口腔科学   39篇
临床医学   311篇
内科学   548篇
皮肤病学   88篇
神经病学   237篇
特种医学   37篇
外科学   372篇
综合类   343篇
预防医学   467篇
眼科学   22篇
药学   207篇
中国医学   247篇
肿瘤学   119篇
  2024年   5篇
  2023年   40篇
  2022年   63篇
  2021年   111篇
  2020年   130篇
  2019年   125篇
  2018年   136篇
  2017年   115篇
  2016年   92篇
  2015年   102篇
  2014年   197篇
  2013年   244篇
  2012年   160篇
  2011年   214篇
  2010年   172篇
  2009年   186篇
  2008年   169篇
  2007年   189篇
  2006年   134篇
  2005年   168篇
  2004年   110篇
  2003年   80篇
  2002年   69篇
  2001年   84篇
  2000年   58篇
  1999年   53篇
  1998年   34篇
  1997年   22篇
  1996年   23篇
  1995年   37篇
  1994年   19篇
  1993年   12篇
  1992年   10篇
  1991年   6篇
  1990年   3篇
  1989年   5篇
  1986年   4篇
  1985年   13篇
  1984年   13篇
  1983年   7篇
  1982年   12篇
  1981年   16篇
  1980年   11篇
  1979年   12篇
  1978年   6篇
  1977年   6篇
  1976年   8篇
  1975年   3篇
  1974年   7篇
  1973年   3篇
排序方式: 共有3504条查询结果,搜索用时 15 毫秒
1.
2.
《Brain stimulation》2022,15(2):337-351
BackgroundAbnormalities in frontoparietal network (FPN) were observed in many neuropsychiatric diseases including substance use disorders. A growing number of studies are using dual-site-tACS with frontoparietal synchronization to engage this network. However, a computational pathway to inform and optimize parameter space for frontoparietal synchronization is still lacking. In this case study, in a group of participants with methamphetamine use disorders, we proposed a computational pathway to extract optimal electrode montage while accounting for stimulation intensity using structural and functional MRI.MethodsSixty methamphetamine users completed an fMRI drug cue-reactivity task. Four main steps were taken to define electrode montage and adjust stimulation intensity using 4x1 high-definition (HD) electrodes for a dual-site-tACS; (1) Frontal seed was defined based on the maximum electric fields (EF) predicted by simulation of HD montage over DLPFC (F3/F4 in EEG 10–10), (2) frontal seed-to-whole brain context-dependent correlation was calculated to determine connected regions to frontal seeds, (3) center of connected cluster in parietal cortex was selected as a location for placing the second set of HD electrodes to shape the informed montage, (4) individualized head models were used to determine optimal stimulation intensity considering underlying brain structure. The informed montage was compared to montages with large electrodes and classic frontoparietal HD montages (F3-P3/F4-P4) in terms of tACS-induced EF and ROI-to-ROI task-based/resting-state connectivity.ResultsCompared to the large electrodes, HD frontoparietal montages allow for a finer control of the spatial peak fields in the main nodes of the FPN at the cost of lower maximum EF (large-pad/HD: max EF[V/m] = 0.37/0.11, number of cortical sub-regions that EF exceeds 50% of the max = 77/13). For defining stimulation targets based on EF patterns, using group-level head models compared to a single standard head model results in comparable but significantly different seed locations (6.43 mm Euclidean distance between the locations of the frontal maximum EF in standard-space). As expected, significant task-based/resting-state connections were only found between frontal-parietal locations in the informed montage. Cue-induced craving score was correlated with frontoparietal connectivity only in the informed montage (r = ?0.24). Stimulation intensity in the informed montage, and not in the classic HD montage, needs 40% reduction in the parietal site to reduce the disparity in EF between stimulation sites.ConclusionThis study provides some empirical insights to montage and dose selection in dual-site-tACS using individual brain structures and functions and proposes a computational pathway to use head models and functional MRI to define (1) optimum electrode montage for targeting FPN in a context of interest (drug-cue-reactivity) and (2) proper transcranial stimulation intensity.  相似文献   
3.
BackgroundThe number of total hip arthroplasties performed per year is increasing for reasons not fully explained by a growing and aging population. The purpose of this study was to determine the role of patient functional status as an indication for surgery and determine if patients are undergoing surgery at a better functional status than in the past.MethodsA systematic review and meta-analysis of the MEDLINE, EMBASE, and Cochrane databases was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Functional status was assessed using the 36-Item Short-Form Health Survey’s Physical Component Summary score. Only primary procedures were included; revisions were excluded. Articles were screened by 2 independent reviewers with conflicts resolved with a third reviewer. Meta-regression analysis was performed to determine the effect of time, patient age, and gender. Subgroup analysis was performed to compare geographic regions.ResultsA total of 1504 articles were identified. Data from 172 groups representing 18,644 patients recruited from 1990 to 2013 and identified from 107 articles were included. The mean preoperative Physical Component Summary score was 31.2 (95% confidence interval 30.5-31.9) with a 95% prediction interval of 22.6-39.8. The variance across studies was statistically significant (P = .000) with 97.25% true variance. Year of enrollment, age, and the percentage of females were not found to have any significant effect. There were no differences between countries.ConclusionPatients are undergoing total hip arthroplasty at a similar preoperative physical functional status as in the past. Patient age, gender, and location do not influence the functional status at which patients are indicated for surgery.  相似文献   
4.
目的:探讨单孔胸腔镜下肺癌手术术后胸腔引流时间的影响因素。方法:本研究采用回顾性分析方法,回顾我院2018年01月至2019年12月原发性肺癌患者经单孔胸腔镜手术治疗的病例199例。按照术后胸腔引流时间分为两组,Ⅰ组(术后胸腔引流时间<5天)和Ⅱ组(术后胸腔引流时间≥5天)。对于影响术后胸腔引流时间的可能因素在两组间先采用单因素分析的方法筛选,再将筛选出来的对术后胸腔引流时间可能有意义的影响因素进行二项Logistic多因素回归分析。结果:经单因素分析及二项Logistic多因素回归分析结果显示:年龄≥60岁、手术部位、肺段切除术、胸膜粘连、手术时间≥180 min、术后早期下床活动是术后胸腔引流时间的独立影响因素(P<0.05)。结论:对于具有多个延长术后胸腔引流时间的独立影响因素的患者,应制定个体化管理方案,尽可能减少术后胸腔引流时间,减少住院天数,加快患者康复。  相似文献   
5.

BACKGROUND CONTEXT

Health-related quality of life (HRQOL) parameters have been shown to be reliable and valid in patients with adult spinal deformity (ASD). Minimum clinically important difference (MCID) has become increasingly important to clinicians in evaluating patients with a threshold of improvement that is clinically relevant.

PURPOSE

To calculate MCID and minimum detectable change (MDC) values of total scores of the Core Outcome Measures Index (COMI), Oswestry Disability Index (ODI), Physical Component Summary (PCS), Mental Component Summary (MCS) of the Short Form 36 (SF-36), and Scoliosis Research Society 22R (SRS-22R) in surgically and nonsurgically treated ASD patients who have completed an anchor question at pretreatment and 1-year follow-up.

STUDY DESIGN/SETTING

Prospective cohort.

PATIENT SAMPLE

Surgical and nonsurgical patients from a multicenter ASD database.

OUTCOME MEASURES

Self-reported HRQOL measures (COMI, ODI, SF-36, SRS-22R, and anchor question).

METHODS

A total of 185 surgical and 86 nonsurgical patients from a multicenter ASD database who completed pretreatment and 1-year follow-up HRQOL scales and the anchor question at the first year follow-up were included. The anchor question was used to determine MCID for each HRQOL measure. MCIDs were calculated by an anchor-based method using latent class analysis (LCA) and MDCs by a distribution-based method.

RESULTS

All differences between means of baseline and first year postoperative total score measures for all scales demonstrated statistically significant improvements in the overall population as well as the surgically treated patients but not in the nonsurgical group. The calculated MDC and MCID values of HRQOL parameters in the entire study population were 1.34 and 2.62 for COMI, 10.65 and 14.31 for ODI, 6.09 and 7.33 for SF-36 PCS, 6.14 and 4.37 for SF-36 MCS, and 0.42 and 0.71 for SRS-22R. The calculated MCID values for surgical and non-surgical treatment groups were 2.76 versus 1.20 for COMI, 14.96 versus 2.45 for ODI, 7.83 versus 2.15 for SF-36 PCS, 5.14 versus 2.03 for SF-36 MCS, and 0.94 versus 0.11 for SRS-22R; the MDC values for surgical and nonsurgical treatment groups were 1.22 versus 1.51 for COMI, 10.27 versus 9.45 for ODI, 5.16 versus 6.77 for SF-36 PCS, 6.05 versus 5.67 for SF-36 MCS, and 0.38 versus 0.43 for SRS-22R.

CONCLUSIONS

This study has demonstrated that MCID calculations for the HRQOL scales in ASD using LCA yield values comparable to other studies that had used different methodologies. The most important finding was the significantly different MCIDs for COMI, ODI, SF-36 PCS and SRS-22 in the surgically and nonsurgically treated cohorts. This finding suggests that a universal MCID value, inherent to a specific HRQOL for an entire cohort of ASD may not exist. Use of different MCIDs for surgical and nonsurgical patients may be warranted.  相似文献   
6.
本研究选择10μg/ml、20μg/ml、40μg/ml浓度的溴氰菊酯处理白纹伊蚊C6/36细胞,以MMC作为阳性对照物,观察溴氰菊酯处理24h后对C6/36细胞染色体畸变率和姐妹染色单体互换(SCE)频率的影响。结果显示,三个浓度的溴氰菊酯对C6/36细胞染色体畸变率均没有显著影响(P<0.05);溴氰菊酯浓度在40μg/ml时可诱导C6/36细胞SCE频率轻度增高(P>0.05),而溴氰菊酯浓度在10μg/ml、20μg/ml时,对C6/36细胞SCE频率没有诱导作用。表明溴氰菊酯对C6/36细胞的遗传学效应较弱  相似文献   
7.
OBJECTIVE: To assess the functional results, health-related quality of life (QOL) outcomes, and complications in patients with an ileal neobladder in comparison to those with cutaneous diversion (ileal conduit and cutaneostomy). METHODS: Between September 1992 and February 2003, we consecutively performed an ileal neobladder (the Studer method) in 30 patients and cutaneous diversion in 38 patients. In August 2004, questionnaires were mailed to 54 patients. The questionnaire included the validated health-related quality of life (QOL) questionnaire, SF-36 General Health Survey, and a urinary incontinence questionnaire. We also evaluated the functional results in patients with an ileal neobladder and the postoperative complications in patients with both urinary diversions. RESULTS: The data from 41 patients (21 ileal neobladder procedures and 20 cutaneous diversions) were available for the analysis. No differences in the overall QOL were observed between the two groups. Complete daytime and night-time urinary continence was achieved in the 21 patients (100%) and 13 patients (61.9%), respectively. The mean value of the maximum flow rate was 15 +/- 12 mL/min in the 21 neobladder patients. There were 19 early complications in 18 patients (60.0%) and seven late complications in six patients (20.0%) with an ileal neobladder. However, there were 15 early complications in 14 patients (36.8%) and eight late complications in six patients (15.8%) with cutaneous diversions. CONCLUSION: The findings regarding the health-related QOL and the frequency of complications in the neobladder group and those in the cutaneous diversion group were similar. However, the functional results and the status of urinary continence in the neobladder patients were satisfactory.  相似文献   
8.
OBJECTIVE: Surgery for Crohn's disease (CD) is associated with a high recurrence rate and quality of life (QOL) in these patients is controversial. The aim of this study was to assess QOL in patients after laparoscopic and open surgery for CD by two different validated instruments, a generic nonspecific score and a specific gastrointestinal QOL index. PATIENTS AND METHODS: Patients with CD who underwent elective laparoscopic or open ileocaecal resection with primary anastomosis between 1992 and 2000 were followed for recurrence and surgery-related complications. QOL was assessed by the SF-36 Health Survey containing a mental (MCS) and a physical (PCS) component summary score and by the Gastrointestinal Quality of Life Index (GIQLI) developed by Eypasch. RESULTS: Thirty-seven patients with a mean age of 48.8 +/- 18.4 years including 23 females and 14 males were evaluated at a mean follow-up of 42.6 +/-25.8 months (minimum of 8 months). Twenty-one (57%) patients underwent laparoscopic resection and 16 (43%) open surgery. Both groups were well matched for age, gender, ASA class and body mass index. Fourteen (38%) patients developed recurrent disease and 3 (8%) had postoperative incisional hernias. Overall, QOL scores were 103 +/- 26.8 for the GIQLI, 47.2 +/- 11.8 for the PCS, and 49.2 +/- 11.5 for the MCS. The GIQLI correlated well with the SF36, correlation coefficient = 0.68 for GIQLI vs PCS (95% CI, 0.41,0.95) and 0.67 for GIQLI vs MCS (95%CI, 0.39, 0.95), respectively. When compared to the general US population, mean GIQLI scores (-13.8, P = 0.002) and mean PCS scores (-4.7, P = 0.001) were significantly lower in these patients than in healthy individuals. In a multivariate analysis of impact factors on QOL, recurrence within the follow-up period was the single significant determinant reducing the PCS (-35.1, P = 0.026) and the GIQLI (-36.1, P = 0.018). CONCLUSION: QOL is significantly reduced in patients with CD at long-term follow-up after both laparoscopic and open surgery. Recurrence is the only factor adversely affecting QOL of CD patients in remission irrespective of the operative technique applied.  相似文献   
9.
[目的]探讨不同起搏模式对病人生存质量(QOL)的影响。[方法]以健康调查问卷(SF一36量表)对112例不同起搏模式病人进行问卷调查,比较3种起搏模式下病人的QOL水平。[结果]除机体疼痛、角色情绪2个维度外其余6个维度(生理功能、角色限制、活力、社会功能、精神健康、总体健康)3种起搏模式间比较差异有统计学意义(P〈0.05)。[结论]应用AAI型、DDD型起搏器的病人生存质量优于VVI型起搏。  相似文献   
10.
电针足三里穴对人体幽门运动功能影响的研究   总被引:9,自引:0,他引:9       下载免费PDF全文
应用内镜测压术,检测电针足三里穴前后部分健康成人和胃、十二指肠疾病患者幽门括约肌压力参数变化。结果表明:电针足三里穴对幽门括约肌压力波参数的影响主要表现为升高低振幅波和降低高振幅波,与电针非经穴点的单纯抑制效应有显著区别。提示电针足三里穴有兴奋和抑制幽门括约肌功能的双相调节效应。  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