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   1709篇
  免费   180篇
  国内免费   37篇
耳鼻咽喉   22篇
儿科学   101篇
妇产科学   28篇
基础医学   150篇
口腔科学   15篇
临床医学   277篇
内科学   273篇
皮肤病学   32篇
神经病学   118篇
特种医学   78篇
外科学   321篇
综合类   74篇
一般理论   1篇
预防医学   158篇
眼科学   15篇
药学   148篇
中国医学   2篇
肿瘤学   113篇
  2021年   14篇
  2020年   11篇
  2019年   23篇
  2018年   32篇
  2017年   13篇
  2016年   15篇
  2015年   16篇
  2014年   33篇
  2013年   42篇
  2012年   54篇
  2011年   65篇
  2010年   38篇
  2009年   37篇
  2008年   62篇
  2007年   85篇
  2006年   89篇
  2005年   91篇
  2004年   59篇
  2003年   60篇
  2002年   73篇
  2001年   54篇
  2000年   63篇
  1999年   63篇
  1998年   39篇
  1997年   33篇
  1996年   34篇
  1995年   41篇
  1994年   36篇
  1993年   39篇
  1992年   52篇
  1991年   43篇
  1990年   34篇
  1989年   46篇
  1988年   42篇
  1987年   35篇
  1986年   33篇
  1985年   25篇
  1984年   21篇
  1983年   16篇
  1982年   22篇
  1981年   13篇
  1980年   11篇
  1979年   12篇
  1976年   11篇
  1974年   21篇
  1972年   14篇
  1971年   13篇
  1970年   18篇
  1968年   11篇
  1966年   10篇
排序方式: 共有1926条查询结果,搜索用时 15 毫秒
71.
OBJECTIVE: Conventional surgical management of prolapsing haemorrhoids is by excisional haemorrhoidectomy. Postoperative pain has restricted the application of such procedures in the day case setting. These operations remain associated with a period of restricted activity. The use of circular stapling devices as an alternative to the excisional approach in the management of haemorrhoids has been described. This study reports our experience of stapled haemorrhoidopexy as a day case procedure. METHODS: Patients with third or fourth degree haemorrhoids were eligible for the procedure. Patients were considered suitable candidates for day case surgery based on conventional parameters. Symptoms were assessed using a previously validated symptom severity rating score. Stapled haemorrhoidopexy was carried out using a circular stapling device. Pain scores were obtained prior to discharge. Patients were admitted if pain was uncontrolled despite oral analgesia. Symptoms were re-scored at six-week follow-up. RESULTS: Over a 70-month period 168 consecutive stapled haemorrhoidopexies were performed or directly supervised by one consultant colorectal surgeon. One hundred and ten (65%) patients were considered appropriate candidates for day case surgery by conventional criteria. Ninety-six (87.3%) patients successfully underwent stapled haemorrhoidopexy on a day case basis. Fourteen (12.7%) patients required admission on the day of surgery (5 for early postoperative bleeding, 4 for pain necessitating continuing opiate analgesia, two for urinary retention and three for surgery performed late in the day). Six (5%) patients were re-admitted postoperatively; four for pain relief and two because of urinary retention. Of the day case patients, 91 (82.7%) and 56 (50.9%) had been seen for 6 week and 6 month review, respectively, at the time of analysis. Symptom scores were 6 (pre-operatively) vs 0 (postoperatively) (P < 0.01). 76/91 (83.5%) patients reviewed at 6/52 were asymptomatic. CONCLUSION: Stapled haemorrhoidopexy is a safe and effective procedure that can be carried out on selected patients on a day case basis. Complications are of a similar nature to excisional haemorrhoidectomy.  相似文献   
72.

Background

The STOP-BANG questionnaire screens for obstructive sleep apnoea (OSA) in surgical patients. In prior research, the association of STOP-BANG scores with comorbidities and outcomes was inconsistent. The objective of this study was to evaluate the validity of the STOP-BANG score.

Methods

We conducted a retrospective cohort study of patients undergoing major elective noncardiac surgery at the University Health Network (Toronto, ON, Canada) between 2011 and 2015. Cross-sectional construct validity was evaluated based on proportions with diagnosed OSA across STOP-BANG strata. Concurrent construct validity was assessed based on the correlation of STOP-BANG with ASA Physical Status (ASA-PS), the Revised Cardiac Risk Index, and the Charlson Comorbidity Index. Predictive validity was assessed based on the adjusted associations of STOP-BANG risk with 30-day mortality (logistic regression), cardiac complications (logistic regression), and length-of-stay (negative binomial regression).

Results

Of 26 068 patients in the cohort, 58% were in the low-risk STOP-BANG stratum, 23% in the intermediate-risk stratum, and 19% in the high-risk stratum. The proportion with previously diagnosed OSA was 4% (n=615) in the low-risk stratum, 12% (n=740) in the intermediate-risk stratum, and 44% (n=2142) in the high-risk stratum. The correlations of STOP-BANG with ASA-PS (Spearman ρ=0.28), Revised Cardiac Risk Index (ρ=0.24), and Charlson Comorbidity Index (ρ=0.10) were weak, albeit statistically significant (P<0.001). After risk-adjustment, STOP-BANG risk strata were not associated with 30-day mortality, cardiac complications, or length-of-stay.

Conclusions

The STOP-BANG questionnaire has modest construct validity but did not predict postoperative mortality, hospital length-of-stay, or cardiac complications.  相似文献   
73.

Introduction

Female sex workers (FSWs) frequently experience violence, harassment and arrest by the police or their clients, but there is little evidence as to the impact that such factors may have on HIV risk or whether community interventions could mitigate this impact.

Methods

As part of the evaluation of the Avahan programme in Karnataka, serial integrated behavioural and biological assessment (IBBA) surveys (four districts) (2005 to 2011) and anonymous polling booth surveys (PBS) (16 districts) (2007 to 2011) were conducted with random samples of FSWs. Logistic regression analysis was used to assess 1) changes in reported violence and arrests over time and 2) associations between violence by non-partners and police arrest and HIV/STI risk and prevalence. Mediation analysis was used to identify mediating factors.

Results

5,792 FSWs participated in the IBBAs and 15,813 participated in the PBS. Over time, there were significant reductions in the percentages of FSWs reporting being raped in the past year (PBS) (30.0% in 2007, 10.0% in 2011, p<0.001), being arrested in the past year [adjusted odds ratio (AOR) 0.57 (0.35, 0.93), p=0.025] and being beaten in the past six months by a non-partner (clients, police, pimps, strangers, rowdies) [AOR 0.69 (0.49, 0.95), p=0.024)] (IBBA). The proportion drinking alcohol (during the past week) also fell significantly (32.5% in 2005, 24.9% in 2008, 16.8% in 2011; p<0.001). Violence by non-partners (being raped in the past year and/or beaten in the past six months) and being arrested in the past year were both strongly associated with HIV infection [AOR 1.59 (1.18, 2.15), p=0.002; AOR 1.91 (1.17, 3.12), p=0.01, respectively]. They were also associated with drinking alcohol (during the past week) [AOR 1.98 (1.54, 2.53), p<0.001; AOR 2.79 (1.93, 4.04), p<0.001, respectively], reduced condom self-efficacy with clients [AOR 0.36 (0.27, 0.47), p<0.001; AOR 0.62 (0.39, 0.98), p=0.039, respectively], symptomatic STI (during the past year) [AOR 2.62 (2.07, 3.30), p<0.001; AOR 2.17 (1.51, 3.13), p<0.001, respectively], gonorrhoea infection [AOR 2.79 (1.51, 5.15), p=0.001; AOR 2.69 (0.96, 7.56), p=0.060, respectively] and syphilis infection [AOR 1.86 (1.04, 3.31), p=0.036; AOR 3.35 (1.78, 6.28), p<0.001, respectively], but not with exposure to peer education, community mobilization or HIV testing uptake. Mediation analysis suggests that alcohol use and STIs may partially mediate the association between violence or arrests and HIV prevalence.

Discussion

Violence by non-partners and arrest are both strongly associated with HIV infection among FSWs. Large-scale, comprehensive HIV prevention programming can reduce violence, arrests and HIV/STI infection among FSWs.  相似文献   
74.
Beattie S 《RN》2000,63(3):26-9; quiz 30
  相似文献   
75.
Twenty-eight patients suffering from cystic fibrosis, with an age range of 8-21 years entered a randomised cross-over trial to study the efficacy of the Positive Expiratory Pressure (PEP) mask as a method of chest physiotherapy, both on its own and in conjunction with other physiotherapy techniques. Twenty-four of these patients completed the trial consisting of 4 treatment programmes each lasting one month and with no wash-out period between them. Five of these patients went on to a fifth programme of Forced Expiratory Technique (FET) alone. At the end of the trial, no significant difference was found between the programmes as regards growth, Shwachman score, Chrispin-Norman score or pulmonary function tests. Twenty-three patients chose to continue using the PEP mask in conjunction with FET long-term as their chest physiotherapy programme as they felt it was an effective treatment allowing increased independence, with postural drainage being kept to a minimum.  相似文献   
76.
Word recognition functions for Auditec recordings of the CID W-22 stimuli in multitalker noise were obtained using subjects with normal hearing and with mild-to-moderate sensorineural hearing loss. In the first experiment, word recognition functions were generated by varying the signal-to-noise ratio (S/N); whereas in the second experiment, a constant S/N was used and stimulus intensity was varied. The split-half reliability of word recognition scores for the normal-hearing and hearing-impaired groups revealed variability that agreed closely with predictions based on the simple binomial distribution. Therefore, the binomial model appears appropriate for estimating the variability of word recognition scores whether they are obtained in quiet or in a competing background noise. The reliability for threshold (50% point) revealed good stability. The slope of the recognition function was steeper for normal listeners than for the hearing-impaired subjects. Word recognition testing in noise can provide insight into the problems imposed by hearing loss, particularly when evaluating patients with mild hearing loss who exhibit no difficulties with conventional tests. Clinicians should employ a sufficient number of stimuli so that the test is adequately sensitive to differences among listening conditions.  相似文献   
77.
78.
Reliability of threshold, slope, and PB max for monosyllabic words   总被引:1,自引:0,他引:1  
The Auditec recordings of the CID W-22 monosyllables were used to generate test and retest intelligibility functions on normally hearing listeners and subjects with mild-to-moderate sensorineural hearing loss. The normally hearing subjects were tested with 50-word lists at SPLs ranging from 15 to 50 dB. Lists of 25 words were used with the hearing-impaired group. The functions were analyzed to assess the reliability of threshold (50% point), slope (20%-80% points), and maximum intelligibility (PB max). The 50% point was obtained at 28 dB SPL for the normally hearing listeners and at a sensation level (SL) of 12 dB respondaic thresholds for the hearing-impaired group. Very stable monosyllabic thresholds were found because 95% of the test-retest values were within 6 dB for both subject groups. Slopes of 4.9% per dB and 2.7% per dB were obtained for the normally hearing and hearing-impaired groups, respectively. Fair reliability was observed; 95% of the test-retest values encompassed a range of +/- 1.9% per dB for the normally hearing subjects and +/- 1.1% per dB for the hearing-impaired group. Although group slopes provide useful information for selecting the range and step size for generating psychometric functions, the value of routinely obtaining slope on an individual basis has not been demonstrated. Even though the same word lists were used for both test and retest measurements, reliability closely agreed with predicted results based on the binomial theorem. In contrast to the large variability for a single list of 25 words, very stable PB max scores were found when two or three scores were averaged on the plateau of the function.  相似文献   
79.
This study examined the effects of electrode placement on the early auditory evoked response in normally hearing subjects. The electrodes are termed noninverting, inverting, and common. Ten commonly used electrode combinations were evaluated. Both amplitudes and latencies of Waves I, III, and V were measured for each electrode combination. No mean differences in latencies were observed for Waves I, III, or V with any of the 10 electrode combinations. Similarly, no statistically significant Wave I or Wave III amplitude differences were found among the 10 electrode montages. However, larger Wave V amplitudes were found with placement of the noninverting electrode at the vertex (0.53 mu v) as compared to the upper forehead (0.39 mu v). Moreover, Wave V amplitudes were larger for inverting/common electrode placements at the seventh cervical vertebra/forehead, neck/forehead, and neck/neck (approximately 0.50 mu v) than for mastoid/mastoid and mastoid/forehead placements (approximately 0.40 mu v). Thus, three combinations of electrodes gave the largest Wave V amplitudes. These placements for the noninverting, inverting, and common electrodes, respectively, were (a) vertex-seventh-forehead, (b) vertex-neck-forehead, and (c) vertex-neck-neck.  相似文献   
80.
The effect of S/N from +20 to -10 db on loudness levels of connected discourse with or without background cafeteria noise was investigated for one set of instructions sampling the most comfortable loudness level (MCLL) and a second set sampling the upper limit of CLL. Normal young adults (N:16) showed no significant differences for either set of instructions in quiet or from 20 to 0 db S/N but mn MCLL was about 5 db lower at -10 db. Elderly hearing-aid wearers (N:10, mn age: 77 yrs) yielded mn differences across S/N of less than 5 db for either set of instructions. No data indicate that the speech CLL accurately predicts optimal hearing-aid gain, while the literature indicates that occasionally the desired maximum intelligibility frequently is not obtained at the MCLL. We question whether MCLL for speech justifies its measurement. A discussion is presented of the Comfort Level Method of adjusting gain in hearing-aid evaluations and a perhaps preferable Threshold Level Method in which the test stimulus is presented at a level corresponding to the predicted threshold and the aid's volume control is adjusted until S just perceives the signal.  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