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   2935篇
  免费   180篇
  国内免费   27篇
耳鼻咽喉   62篇
儿科学   185篇
妇产科学   35篇
基础医学   304篇
口腔科学   110篇
临床医学   212篇
内科学   595篇
皮肤病学   73篇
神经病学   225篇
特种医学   174篇
外科学   448篇
综合类   96篇
预防医学   99篇
眼科学   97篇
药学   210篇
中国医学   14篇
肿瘤学   203篇
  2023年   21篇
  2022年   62篇
  2021年   140篇
  2020年   70篇
  2019年   94篇
  2018年   103篇
  2017年   79篇
  2016年   101篇
  2015年   91篇
  2014年   154篇
  2013年   154篇
  2012年   222篇
  2011年   185篇
  2010年   127篇
  2009年   74篇
  2008年   109篇
  2007年   140篇
  2006年   149篇
  2005年   115篇
  2004年   98篇
  2003年   68篇
  2002年   58篇
  2001年   52篇
  2000年   65篇
  1999年   58篇
  1998年   47篇
  1997年   40篇
  1996年   29篇
  1995年   17篇
  1994年   19篇
  1993年   15篇
  1992年   23篇
  1991年   25篇
  1990年   30篇
  1989年   23篇
  1988年   19篇
  1987年   25篇
  1986年   22篇
  1985年   20篇
  1984年   22篇
  1983年   17篇
  1982年   11篇
  1978年   11篇
  1977年   13篇
  1976年   9篇
  1975年   16篇
  1974年   11篇
  1973年   9篇
  1972年   10篇
  1971年   11篇
排序方式: 共有3142条查询结果,搜索用时 15 毫秒
61.
There is an increasing awareness for recognition of sleep disorders in India; however, there is still a huge gap in the number of people suffering from various sleep disorders, in the community versus those visiting hospital clinics for the same. Ours is a neurology services-based sleep disorders clinic, which has evolved successfully over the last decade. In this study, we aimed to evaluate the changes in referral patterns and distribution of various sleep disorders in the patients presenting to the clinic.

Materials and Methods:

This is a retrospective chart review-based study on all patients seen over an 8-year period, divided into 2 groups comprising of patients seen during the first 4 years versus those seen over the next 4 years. Only those patients who had the sleep disorder as their presenting manifestation and those who had been formally interviewed with a pre-structured questionnaire detailing about the main features of the common sleep disorders according to the ICSD-R were included. Patients, in whom the sleep disorder could be clearly attributable to another neurological or systemic disorder, were excluded. Statistical analysis was carried out to identify the differences between the two groups as regards the distribution of various sleep disorders and other clinical data.

Results:

Among 710 patients registered in the clinic, 469 were included for analysis and 222 patients formed group 1 while 247 formed group 2. The main differences observed were in the form of a clear increase in the percentage of patients with sleep-related breathing disorders, sleep-related movement disorder, and the hypersomnias on comparison of distribution over the first 4 years versus the last 4 years; while a clear decline was seen in the number of patients with insomnia and parasomnias. A 3-fold increase was observed in the number of patients in whom polysomnography was obtained.

Conclusion:

The distribution of various sleep disorders as seen in a neurology service-based sleep clinic is demonstrated in this study. Increasing referrals for sleep-disordered breathing, restless legs syndrome, and fewer referrals for insomnia and parasomnias might reflect on changing physician and patient awareness in our community.  相似文献   
62.
Our aim was to compare the use of a conventional rotary handpiece and a Piezosurgical unit for extraction of lower third molars. We studied 40 patients, who were allocated alternately to have the third molar removed with either the handpiece or the Piezosurgical unit. Pain, trismus, and oedema were evaluated at baseline and then postoperatively, together with paraesthesiae, on postoperative days 1, 3, 5, 7, and 15. Damage to surrounding tissue was checked on the same day whereas dry socket was evaluated from postoperative day 3 onwards. More patients complained of pain in the conventional group, they also required more analgesics, and they developed trismus more often than in the Piezosurgery group. There was also significantly more postoperative swelling in the conventional group. Patients were also evaluated using the subjective Postoperative Symptom Severity (PoSSe) scale. Our results suggest that apart from some inherent limitations with the Piezotome, it is a valuable alternative for extraction of third molars.  相似文献   
63.
64.
65.
The objective of the present study is to improve iron bioavailability using high-density gastroretentive pellets of zero valent iron nanoparticles (ZVINPs). ZVINPs were prepared by the chemical reduction method and were characterized for surface morphology, surface charge, and thermal properties. High-density gastroretentive pellets of iron nanoparticles were prepared using spheronization technique. Pellets were characterized for its micromeritic properties, in vitro drug release, and ex vivo permeability. The pharmacokinetic parameters, organ distribution, and toxicity of the optimized pellets were investigated in Wistar rats. In vivo results revealed more than 2-fold increases in oral bioavailability of iron by pellets compared to plane ferrous sulfate. Toxicological studies of the carriers indicated no evidence of liver damage in acute treatment; however, few complications were observed in chronic treatment groups. These results indicated that ZVINPs pellets successfully improve the oral iron bioavailability but need to obtain more information on repeated dose toxicity to initiate the clinical evaluation of investigational products.  相似文献   
66.
The right kidney of anesthetized rats was imaged with intermittent diagnostic ultrasound (1.5 MHz; 1-s trigger interval) under exposure conditions simulating those encountered in human perfusion imaging. The rats were infused intravenously with 10 microL/kg/min Definity (Bristol-Myers Squibb Medical Imaging, Inc., N. Billerica, MA, USA) while being exposed to mechanical index (MI) values of up to 1.5 for 1 min. Suprathreshold MI values ruptured glomerular capillaries, resulting in blood filling Bowman's space and proximal convoluted tubules of many nephrons. The re-establishment of a pressure gradient after hemostasis caused the uninjured portions of the glomerular capillaries to resume the production of urinary filtrate, which washed some or all of the erythrocytes out of Bowman's space and cleared blood cells from some nephrons into urine within six hours. However, many of the injured nephrons remained plugged with tightly packed red cell casts 24 h after imaging and also showed degeneration of tubular epithelium, indicative of acute tubular necrosis. The additional damage caused by the extravasated blood amplified that caused by the original cavitating gas body. Human nephrons are virtually identical to those of the rat and so it is probable that similar glomerular capillary rupture followed by transient blockage and/or epithelial degeneration will occur after clinical exposures using similar high MI intermittent imaging with gas body contrast agents. The detection of blood in postimaging urine samples using standard hematuria tests would confirm whether or not clinical protocols need to be developed to avoid this potential for iatrogenic injury.  相似文献   
67.
OBJECTIVE: To evaluate the safety and plaque removal efficacy of an advanced rotating-oscillating power toothbrush relative to a sonic toothbrush with either a standard or compact brush head. METHODOLOGY: Two studies used a randomized, examiner-blind, two-treatment, crossover design. In Study 1, subjects were instructed to use their first randomly assigned toothbrush for five to seven days and then, after abstaining from all oral hygiene for 24 hours, were assessed with the Rustogi, et al. Modified Navy Plaque Index. They then brushed for two minutes and post-brushing plaque scores were recorded. Subjects were assigned to the alternate toothbrush and the procedures were repeated. In Study 2, subjects alternated using both brushes for approximately 10 days, then had four study visits three to four days apart (some variability based on patient scheduling). In Study 1, Oral-B Triumph with a FlossAction brush head and Sonicare Elite 7300 with a full-size, standard head were compared in a two-treatment, two-period crossover study. Study 2 compared Oral-B Triumph with a FlossAction brush head and Sonicare Elite 7300 with a compact head in a two-treatment, four-period crossover study. RESULTS: Fifty subjects completed Study 1 and 48 completed Study 2. All brushes were found to be safe and significantly reduced plaque after a single brushing. In Study 1, Oral-B Triumph was statistically significantly (p < 0.001) more effective in plaque removal than Sonicare Elite 7300 with the full-size brush head: whole mouth = 24% better, marginal = 31% better, approximal = 21% better. In Study 2, Oral-B Triumph was statistically significantly (p < 0.001) more effective than Sonicare Elite 7300 with the compact brush head: whole mouth = 12.2% better, marginal = 14.6% better, approximal = 12% better. CONCLUSION: Oral-B Triumph with its rotation-oscillation action was significantly more effective in single-use plaque removal than Sonicare Elite 7300 with its side-to-side sonic action when fitted with either a standard or a compact brush head.  相似文献   
68.
We performed studies in the opossum to define the influence of the vagi in the control of lower esophageal sphincter (LES) function. Bilateral vagotomy caused transient sphincter hypertension which was prevented by phentolamine and by atropine. Stimulation of the peripheral end of vagus, after bilateral cervical vagotomy, caused relaxation of the LES over a wide range of frequency and intensity of electrical stimulation. The relaxation was less marked at the lower frequencies of stimulation, and atropine treatment did not enhance this relaxation. In other experiments, atropine treatment reversed the rise in gastric (fundic) pressure with the vagal stimulation, but atropine did not enhance the degree of LES relaxation. Stimulation of the central end of the vagus caused an increase in LES pressure due to a centrally mediated reflex; the efferents for this motor response were not present in the vagi, as the reflex contraction persisted after bilateral vagotomy. The LES contraction with the stimulation of the vagal afferents was antagonized by phentolamine as well as by atropine. These studies suggest that: (a) the vagi do not mediate any cholinergic excitatory influences to the LES and the vagal influence of the sphincter is entirely inhibitory; (b) the vagi carry afferent fibres for a centrally mediated neural reflex which contracts the LES, but the efferent path of this reflex arc does not lie in the vagi.  相似文献   
69.
The coronavirus disease‐2019 (COVID‐19) pandemic has rapidly spread across the world, placing unprecedented strain on the health care system. Health care resources including hospital beds, ICUs, as well as personal protective equipment are becoming increasingly rationed and scare commodities. In this environment, the laryngectomee (patient having previously undergone a total laryngectomy) continues to represent a unique patient with unique needs. Given their surgically altered airway, they pose a challenge to manage for the otolaryngologist within the current COVID‐19 pandemic. In this brief report, we present special considerations and best practice recommendations in the management of total laryngectomy patients. We also discuss recommendations for laryngectomy patients and minimizing community exposures.  相似文献   
70.
Purpose: Carpal tunnel syndrome is a common disease treated operatively. During the operation, the patient may be wide-awake or sedated. The current literature has only compared separate cohorts. We sought to compare patient experience with both local-only anesthesia and sedation. Methods: Staged bilateral carpal tunnel release utilizing open or endoscopic technique was scheduled and followed through to completion of per-protocol analysis in 31 patients. Patients chose initial hand laterality and were randomized regarding initial anesthesia method: local-only or sedation. Data collection via questionnaires began at consent and continued to 6 weeks postoperatively from second procedure. Primary outcome measures included patient satisfaction and patient anesthesia preference. Results: At final follow-up, 6 weeks postoperatively, high satisfaction (30 of 31 patients per method) was reported with both types of anesthesia. Among these patients, 17 (54%) preferred local-only anesthesia, 10 (34%) preferred sedation, 2 had no preference, and 2 opted out of response. Although anesthesia fees were approximately $390 lower with local-only anesthesia, total costs for carpal tunnel release were not significantly different with respect to the anesthesia cohorts. Total time in surgical facility was approximately 26 minutes quicker with local-only anesthesia, largely due to shorter time in the post-anesthesia care unit. Scaled comparison of worst postoperative pain following the 2 procedures revealed no difference between local-only anesthesia and sedation. Conclusions: Patients reported equal satisfaction scores with carpal tunnel release whether performed under local-only anesthesia or with sedation. In addition, local-only anesthesia was indicated as the preference of patients in 59% of cases.  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