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   3364694篇
  免费   255267篇
  国内免费   8839篇
耳鼻咽喉   45626篇
儿科学   110149篇
妇产科学   91887篇
基础医学   474210篇
口腔科学   94324篇
临床医学   309062篇
内科学   661500篇
皮肤病学   77236篇
神经病学   277859篇
特种医学   131063篇
外国民族医学   952篇
外科学   504057篇
综合类   72861篇
现状与发展   5篇
一般理论   1291篇
预防医学   265838篇
眼科学   74838篇
药学   246893篇
  11篇
中国医学   6629篇
肿瘤学   182509篇
  2019年   26163篇
  2018年   36925篇
  2017年   28330篇
  2016年   32608篇
  2015年   36767篇
  2014年   50984篇
  2013年   77020篇
  2012年   101867篇
  2011年   108042篇
  2010年   65128篇
  2009年   62328篇
  2008年   100794篇
  2007年   107331篇
  2006年   109110篇
  2005年   104940篇
  2004年   101116篇
  2003年   97512篇
  2002年   93931篇
  2001年   162033篇
  2000年   166451篇
  1999年   140034篇
  1998年   40448篇
  1997年   35968篇
  1996年   36443篇
  1995年   35406篇
  1994年   32679篇
  1993年   30564篇
  1992年   110412篇
  1991年   106608篇
  1990年   103252篇
  1989年   99390篇
  1988年   91318篇
  1987年   89727篇
  1986年   84421篇
  1985年   80671篇
  1984年   60447篇
  1983年   51149篇
  1982年   30425篇
  1981年   27263篇
  1979年   53928篇
  1978年   38315篇
  1977年   32341篇
  1976年   30041篇
  1975年   32050篇
  1974年   38032篇
  1973年   36275篇
  1972年   33882篇
  1971年   31446篇
  1970年   28925篇
  1969年   27527篇
排序方式: 共有10000条查询结果,搜索用时 468 毫秒
961.
STUDY OBJECTIVES: Use of fast track has been shown to improve the emergency department flow of less urgent patients. It has been speculated, however, that this could negatively affect the care of urgent patients. The objective of this study was to determine whether a dedicated fast track for less urgent patients [Canadian Triage and Acuity scale category 4/5 (CTAS 4/5)] affected (1) the time to assessment for urgent patients (CTAS 3), (2) the length of stay for less urgent patients (CTAS 4 and 5), and (3) the left-without-being-seen rate. METHODS: In June 2003, fast track was opened in our emergency department from 13:00 to 19:00 h. A before-after intervention comparison analysis was completed for 1 week in Aug 2002 and the same week in Aug 2003. Data collected included (1) time to assessment of CTAS 3 patients, (2) the length of stay for CTAS 4/5 patients, and (3) percentage of patients who left without being seen. RESULTS: A total of 368 patients were reviewed for 2002 and 380 patients were reviewed for 2003. Median time to assessment of CTAS 3 patients presenting from 13:00 to 19:00 h was reduced from 66 min (Interquartile range: 40, 94 min) in 2002 to 60 min (IQR: 38, 108 min) after fast track was open in 2003 (P = 0.95). Median length of stay of CTAS 4 and 5 patients was reduced from 170 min (IQR: 111, 256 min) to 110 min (IQR: 69, 185 min) (P < 0.001). The overall left-without-being-seen rate decreased from 5% (20/368) to 2% (9/380). CONCLUSION: A dedicated fast track for CTAS 4/5 patients can reduce the length of stay and the left-without-being-seen rate with no impact on CTAS 3 patients seen in the main emergency department.  相似文献   
962.
963.
Southgate  M. Therese 《JAMA》2006,296(13):1564
  相似文献   
964.
The purpose of this study was to evaluate sexual function in women referred to a urogynecology practice. All new patients were mailed an optional female sexual function index (FSFI) in conjunction with their history forms; other sexual function information was obtained during the physician interview. Over 6 months, four hundred fifty new patients were enrolled. Of these, 243 (54%) were not sexually active. Reasons listed for sexual inactivity included partner problems/no partner (32%), low desire (14%), prolapse (10%), and pain (10%). There were several differences between sexually active and non-sexually active participants; however, after a multivariate analysis, only age, marital status, and stage/grade 1–2 of prolapse remained significant. One hundred nine sexually active patients completed the FSFI; the majority was sexually active two to four times per month. Female sexual dysfunction was noted in 70 (64%) patients. Lowest scores were noted for the domain of desire, followed by arousal, orgasm, lubrication, satisfaction, and pain. Reduced frequency of intercourse was the only factor significantly associated with dysfunction. Ninety-four percent were not embarrassed by the survey. Overall, sexual inactivity is common in patients presenting for urogynecologic care. Those that are sexually active report low rates of sexual activity and high rates of sexual dysfunction. Most sexually active patients will accept a sexual function questionnaire as part of their routine assessment.This research was presented at the American College of Obstetricians and Gynecologists annual clinical meeting, May 10, 2005, San Francisco, CA, USA.  相似文献   
965.
966.
Transforaminal injections are sometimes used for the diagnosis and treatment of painful conditions in the lumbar and to a lesser degree in the cervical spine. The technique is most often used when investigating/treating radiculopathy caused by degenerative disease. But how selective are the nerve root blocks? What possible structures other than the intended nerve root are affected from such injections? This study was undertaken in order to try to answer these questions, as no study focusing on the possible spread from the transforaminal selective nerve root blocks in the cervical spine has been performed earlier. In three groups of patients, each group including three patients, we injected three different volumes (0.6, 1.1 and 1.7 ml) with a transforaminal technique in the cervical spine. In all the injections, a small amount of contrast media was added. The spread of the injections were then investigated using multi-slice computed tomography with reconstructions. The imaging revealed a possible effect on other nerve roots than the intended ones when a larger volume was used for the root blocks. The spread was related to the injected volume as well as to local anatomy (size of foraminal area). In this study, only 0.6-ml injections could be accepted for being selective enough for diagnostic investigations.  相似文献   
967.
BACKGROUND AND OBJECTIVES: In 1999, our institution began a kidney transplant program with collaboration between the departments of General Surgery/Transplantation and Urology. From the onset, donor nephrectomies were performed laparoscopically and are currently the domain of Urology, which had no prior laparoscopic experience before this undertaking. We reviewed our experience. METHODS: A database of our experience was kept prospectively from June 1999 to November 2004. Records of both donors and recipients were reviewed. Special attention was directed toward our changes in technique and their relationship to outcomes, with emphasis on graft extraction and overall complication rates. RESULTS: We reviewed the records of 205 consecutive procedures. We report excellent donor outcomes, including mean operative time (112 minutes), estimated blood loss (120 mL), and length of stay (2.3 days). Complication (14.1%) and open conversion (1.5%) rates were low. For the recipients, early (98.0%) and 1-year (94.7%) graft survival, and ureteral ischemia (2.4%) rates were also appropriate with contemporary experience. CONCLUSIONS: We report our results on laparoscopic donor nephrectomy in a de novo renal transplant program. Because of this experience, we have ventured into other horizons of urologic laparoscopy and currently produce enough volume to support a laparoscopic fellowship. We feel that a productive donor nephrectomy program can enhance urologic laparoscopic programs and should be taken advantage of when available.  相似文献   
968.
BACKGROUND: Posterior spinal procedures through tubular exposures have been described. However, tubes restrain visibility and require co-axial instrument manipulation, increasing difficulty and potentially compromising surgical results. An independent-blade retractor system overcomes the obstacles of working through a tube and has been used to perform minimally-disruptive decompression and instrumented tranforaminal lumbar interbody fusion (TLIF). PURPOSE: To evaluate the advantages to patient recovery and surgical efficacy of this technique. METHODS/RESULTS: Retrospective review of technique employing a minimally-disruptive approach to decompression and transforaminal lumber interbody fusion (TLIF). CONCLUSIONS: Minimally-disruptive decompression and instrumented TLIF can be performed in a safe and effective manner using an independent-blade retractor system. Relative to traditional-open techniques, surgical goals can be accomplished, but with the benefits of minimally-disruptive surgery.  相似文献   
969.
INTRODUCTION: The optimal hyperbaric oxygen (HBO2) treatment protocol for acute carbon monoxide (CO) poisoning is unknown. This is indicated by one study that found 18 different protocols to treat CO poisoning by North American multiplace hyperbaric facilities. A pilot study was conducted to evaluate the feasibility of randomizing patients to different protocols and to determine whether any large differences in clinical outcome were present between the two most common protocols. METHODS: Adult patients with accidental CO poisoning resulting in transient loss of consciousness, presentation to the emergency department within 12 hours, primary language English, high school education, and residence within 100 miles of the hyperbaric facility were recruited. Enrolled patients were randomized to one HBO2 treatment at 2.4 atmospheres absolute (atm abs) pressure with 90 minutes of 100% oxygen breathing vs. treatment by the US Air Force CO protocol (3.0 atm abs maximum pressure). A neurocognitive screening test was performed immediately after hyperbaric treatment and repeated 14-21 days later. RESULTS: From 1995 to 2002, 30 patients age 21 to 88 years were randomized, 18 to treatment at 2.4 atm abs and 12 to 3.0 atm abs. Average carboxyhemoglobin level for the population was 24.8 +/- 8.8% (mean +/- SD). Delay to hyperbaric treatment averaged 313 +/- 129 minutes. Neither variable was different between treatment groups. Six patients had abnormal neurocognitive testing immediately following hyperbaric treatment, 4 in the 2.4 atm abs group (22%) and 2 in the 3.0 atm abs group (17%) (P=0.71). One patient in each group demonstrated abnormality on delayed testing (p=0.75). One in each group did not return for follow-up. CONCLUSIONS: It is feasible to randomize CO-poisoned patients to different hyperbaric treatment protocols. Determination of differences in efficacy between treatment protocols will require a large multicenter trial with the use of detailed neurocognitive testing.  相似文献   
970.
166Ho-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene-phosphonate (DOTMP) is a tetraphosphonate molecule radiolabeled with 166Ho that localizes to bone surfaces. This study evaluated pharmacokinetics and radiation-absorbed dose to all organs from this beta-emitting radiopharmaceutical. METHODS: After two 1.1-GBq administrations of 166Ho-DOTMP, data from whole-body counting using a gamma-camera or uptake probe were assessed for reproducibility of whole-body retention in 12 patients with multiple myeloma. The radiation-absorbed dose to normal organs was estimated using MIRD methodology, applying residence times and S values for 166Ho. Marrow dose was estimated from measured activity retained after 18 h. The activity to deliver a therapeutic dose of 25 Gy to the marrow was determined. Methods based on region-of-interest (ROI) and whole-body clearance were evaluated to estimate kidney activity, because the radiotracer is rapidly excreted in the urine. The dose to the surface of the bladder wall was estimated using a dynamic bladder model. RESULTS: In clinical practice, gamma-camera methods were more reliable than uptake probe-based methods for whole-body counting. The intrapatient variability of dose calculations was less than 10% between the 2 tracer studies. Skeletal uptake of 166Ho-DOTMP varied from 19% to 39% (mean, 28%). The activity of 166Ho prescribed for therapy ranged from 38 to 67 GBq (1,030-1,810 mCi). After high-dose therapy, the estimates of absorbed dose to the kidney varied from 1.6 to 4 Gy using the whole-body clearance-based method and from 8.3 to 17.3 Gy using the ROI-based method. Bladder dose ranged from 10 to 20 Gy, bone surface dose ranged from 39 to 57 Gy, and doses to other organs were less than 2 Gy for all patients. Repetitive administration had no impact on tracer biodistribution, pharmacokinetics, or organ dose. CONCLUSION: Pharmacokinetics analysis validated gamma-camera whole-body counting of 166Ho as an appropriate approach to assess clearance and to estimate radiation-absorbed dose to normal organs except the kidneys. Quantitative gamma-camera imaging is difficult and requires scatter subtraction because of the multiple energy emissions of 166Ho. Kidney dose estimates were approximately 5-fold higher when the ROI-based method was used rather than the clearance-based model, and neither appeared reliable. In future clinical trials with 166Ho-DOTMP, we recommend that dose estimation based on the methods described here be used for all organs except the kidneys. Assumptions for the kidney dose require further evaluation.  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