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   4661篇
  免费   219篇
  国内免费   29篇
耳鼻咽喉   111篇
儿科学   250篇
妇产科学   208篇
基础医学   384篇
口腔科学   186篇
临床医学   362篇
内科学   870篇
皮肤病学   83篇
神经病学   362篇
特种医学   119篇
外国民族医学   2篇
外科学   1087篇
综合类   65篇
一般理论   1篇
预防医学   151篇
眼科学   234篇
药学   186篇
中国医学   11篇
肿瘤学   237篇
  2024年   3篇
  2023年   39篇
  2022年   96篇
  2021年   191篇
  2020年   121篇
  2019年   146篇
  2018年   170篇
  2017年   145篇
  2016年   186篇
  2015年   210篇
  2014年   218篇
  2013年   299篇
  2012年   412篇
  2011年   377篇
  2010年   196篇
  2009年   178篇
  2008年   296篇
  2007年   332篇
  2006年   298篇
  2005年   241篇
  2004年   202篇
  2003年   132篇
  2002年   134篇
  2001年   38篇
  2000年   41篇
  1999年   37篇
  1998年   19篇
  1997年   18篇
  1996年   18篇
  1995年   21篇
  1994年   4篇
  1993年   5篇
  1992年   14篇
  1991年   12篇
  1990年   7篇
  1989年   5篇
  1988年   4篇
  1987年   5篇
  1986年   4篇
  1985年   3篇
  1984年   8篇
  1983年   3篇
  1980年   2篇
  1979年   5篇
  1978年   2篇
  1971年   2篇
  1968年   3篇
  1967年   3篇
  1962年   1篇
  1924年   1篇
排序方式: 共有4909条查询结果,搜索用时 62 毫秒
1.
2.

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   
3.
4.
Objective: Trans-sphenoidal surgery is often combined with other approaches for the treatment of middle cranial base tumors. By combining a maxillotomy with trans-sphenoidal approach, significantly wider exposure to these regions is gained. However, endoscope-assisted techniques have also been used for sellar and parasellar and upper clival regions. Methods: An extended trans-sphenoidal approach was performed on 10 cadaver heads using the operating microscope and was repeated with a 0-degree endoscope. The mean horizontal and vertical distances were measured and pictured for each technique, and both distances were compared using a parametric paired Student's t-test. Results: The mean horizontal distances in the 10 specimens were 19.5 ± 1.8 mm by microscope and 27.5 ± 2.2 mm by endoscope, and the mean vertical distances were 25.8 ± 1.9 mm by the microscope and 34.5 ± 3.5 mm by the endoscope. Conclusion: The aim of this study was to quantify the amount of exposure obtained with an extended trans-sphenoidal approach and to compare both endoscopic and microscopic techniques. Using the endoscope in conjunction with the operating microscope may provide additional exposure and better access in skull base surgery.  相似文献   
5.
In this paper, we will discuss a phase-contrast imaging method that avoids the complications of interferometry to provide phase contrast in weakly absorbing samples. A transversely coherent neutron beam is used with the traditional radiography scheme. Images taken with this scheme show dramatic intensity variations due to sharp changes in the neutron wave refractive index. With some numerical processing these images may be used to reconstruct a quantitative phase radiograph of specimens imaged with this technique.  相似文献   
6.
7.
Non-A, non-B is a major form of hepatitis in haemodialysis (HD)patients. Hepatitis C virus (HCV) has been recently identifiedas the leading cause of non-A, non-B hepatitis in HD. A variableprevalence of hepatitis in HD has appeared in the literature,ranging between 1% and 29% in the Western world, and between30% and 54% in Saudi Arabia, but all these reports used first-generationELISA. Using second-generation enzyme immunoassay, we conducteda multi-centre study involving 22 HD centres all over SaudiArabia in order to establish the prevalence and risk factorsfor HCV in HD patients in Saudi Arabia. A total of 1147 patientswere studied, with a mean age of 43.4±15.3 years. Fivehundred and eighty were males and 567 were females. The overallprevalence rate of positive anti-HCV was 68%, with a range fromas low as 14.5%, to 94.7%. To our knowledge, this is the highestvalue reported among dialysis patients world-wide. A positivecorrelation was found between anti-HCV positivity and male sex(P=0.005), longer duration on dialysis (P=0.002) and blood transfusion(P=0.003). However, interestingly 62.6% of the patients whohad not had blood transfusion had anti-HCV antibodies. HCV antibodieswere also found more frequently in Egyptians, Pakistanis andYemenis than in Saudis. A comparison between those centres withlow prevalence of positive HCV and those with high prevalenceregarding risk factors was carried out, and it was found thatthe major difference between them was the adherence of the staffto universal infection precautions. In conclusion, HCV is amajor health problem in HD patients in Saudi Arabia. Identifiablerisk factors are longer duration in dialysis, blood transfusion,male sex, nationality and most importantly the lack of adherenceto universal infection precautions.  相似文献   
8.
9.
Physiological analysis to quantify training load in badminton.   总被引:2,自引:1,他引:1       下载免费PDF全文
OBJECTIVE: To estimate the training load of specific on court training regimens based on the magnitude of variation of heart rate-lactate response during specific training and to determine the magnitude of variation of biochemical parameters (urea, uric acid, and creatine phosphokinase (CPK)) 12 hours after the specific training programme so as to assess training stress. METHODS: The study was conducted on six national male badminton players. Maximum oxygen consumption (VO2), ventilation (VE), heart rate, and respiratory quotient were measured by a protocol of graded treadmill exercise. Twelve training sessions and 35 singles matches were analysed. Heart rate and blood lactate were monitored during technical training routines and match play. Fasting blood samples collected on two occasions--that is, during off season and 12 hours after specific training--were analysed for serum urea, uric acid, and CPK. RESULTS: Analysis of the on court training regimens showed lactate values of 8-10.5 mmol/l in different phases. The percentage of maximum heart rate ranged from 82% to 100%. Urea, uric acid, and CPK activity showed significant changes from (mean (SD)) 4.93 (0.75) mmol/l to 5.49 (0.84) mmol/l, 0.23 (0.04) to 0.33 (0.06) mmol/l, and 312 (211.8) to 363 (216.4) IU/l respectively. CONCLUSION: Maximum lactate reported in the literature ranges from 3-6 mmol/l. Comparatively high lactate values and high percentage of maximum heart rate found in on court training show a considerable stress on muscular and cardiovascular system. The training load needs appropriate monitoring to avoid over-training. Workouts that are too intensive may interfere with coordination, a factor that is important in sports requiring highly technical skill such as badminton.  相似文献   
10.
This study was devised to identify sepsis-relevant parameters that early and reliably predict a lethal outcome in intra-abdominal sepsis. In 18 Duroc pigs, peritonitis was induced through standardized gastrotomy. Twelve hours later the defect was oversewn and the abdominal cavity lavaged thoroughly. Sepsis relevant parameters were measured before initiating therapy, and 30 min later animals were extubated and observed for a period of 6 days under adequate analgesia with free access to water and food. All parameters were correlated with survival postoperatively. In the treatment group, 7 out of 18 pigs (39%) died within the observation period. Endotoxin level at 30 min after initiation of therapy [17.9 EU/mL (+/- 12.1) vs. 110.9 EU/mL (+/- 21); p <.001] and Delta pHi [0.015 (+/- 0.011) vs. -0.039 (+/- 0.013); p =.016] were identified as the two parameters with highest predictive power regarding mortality in a multivariate analysis. In conclusion measurement of endotoxin and gastric tonometry should gain wider clinical application in septic patients.  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