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   3941156篇
  免费   288697篇
  国内免费   11561篇
耳鼻咽喉   55143篇
儿科学   129797篇
妇产科学   107221篇
基础医学   564780篇
口腔科学   111325篇
临床医学   367228篇
内科学   746811篇
皮肤病学   84089篇
神经病学   311890篇
特种医学   148693篇
外国民族医学   1311篇
外科学   577279篇
综合类   104015篇
现状与发展   13篇
一般理论   1483篇
预防医学   323217篇
眼科学   92326篇
药学   293639篇
  22篇
中国医学   14038篇
肿瘤学   207094篇
  2019年   31376篇
  2018年   43529篇
  2017年   32757篇
  2016年   36516篇
  2015年   41379篇
  2014年   58254篇
  2013年   89386篇
  2012年   122091篇
  2011年   133617篇
  2010年   79493篇
  2009年   73679篇
  2008年   122479篇
  2007年   130139篇
  2006年   131286篇
  2005年   128552篇
  2004年   129314篇
  2003年   123926篇
  2002年   118762篇
  2001年   175474篇
  2000年   178924篇
  1999年   152728篇
  1998年   47257篇
  1997年   41578篇
  1996年   40614篇
  1995年   38411篇
  1994年   36084篇
  1993年   34744篇
  1992年   119498篇
  1991年   117341篇
  1990年   113670篇
  1989年   108966篇
  1988年   100572篇
  1987年   98959篇
  1986年   93340篇
  1985年   89312篇
  1984年   67142篇
  1983年   57270篇
  1982年   34264篇
  1981年   30893篇
  1979年   62023篇
  1978年   44150篇
  1977年   37040篇
  1976年   35441篇
  1975年   37910篇
  1974年   45369篇
  1973年   43805篇
  1972年   40892篇
  1971年   38278篇
  1970年   35819篇
  1969年   33387篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Background: Large randomized trials show that in appropriately selected patients with left ventricular dysfunction, implantable cardioverter-defibrillators (ICDs) can improve overall survival at 2–5 years. Since direct implementation of the criteria used in the MADIT II and SCD-HeFT will lead to a marked rise in ICD implants, there is a growing fear that increased use of ICDs may cause a dramatic burden to health care systems. The ICD has traditionally been seen as an expensive form of treatment, which is difficult to accept at the first look. This is mainly due to the nonlinear character of the ICD investment, characterized by high initial expenditure, followed by a deferred pay-off in terms of clinical benefits. Cost-effectiveness analysis may help provide a different perspective on the problem of ICD cost, as may estimation of the daily cost of ICD treatment, assuming a time horizon of 5–7 years—a particularly interesting subject for further registry studies.
Methods and Results: Based on real expenditure data from 2002 to 2005, as recorded in the Search-MI Registry-Italian Sub-study of patients implanted on MADIT II indications, we estimated the daily costs associated with the device and leads. Over a 5–7 year time horizon, the average daily cost was estimated to be €4.60–€6.70. Translation of these figures into U.S. market conditions suggests a daily cost of around $7.90–$11.40.
Conclusions: These findings appear useful to help evaluate the affordability of ICD in comparison with other therapeutic options in a context of limited available economic resources.  相似文献   
992.
993.
To evaluate morbidity associated with surgical lengthening of the gastrocnemius, medical records were reviewed retrospectively for 126 patients (mean age, 49.7 years; range, 8-78 years) who had undergone open gastrocnemius recession. Ten patients had isolated recession; 116 had gastrocnemius recession with an additional foot or ankle procedure on the ipsilateral limb. During a mean follow-up period of 19 months (range, 6-50 months), all patients were examined for any postoperative complications associated with the recession. Complications were defined as the presence of postoperative infection, wound dehiscence, nerve problems, decreased muscle strength, scar problems, or calcaneus gait (overlengthening). Uncomplicated outcome was defined as absence of all these complications and return to regular activity, both occurring during a follow-up of at least 6 months. Postsurgical complications developed in 9 (6%) of the 126 patients: 6 (4%) had scar problems, 2 (1.33%) had wound dehiscence, 2 (1.33%) had infection, 3 (2%) had nerve problems, and 1 (0.67%) developed complex regional pain syndrome. No patient complained of either a limp or gait disturbance. Neither persistent decrease in muscle strength nor calcaneus gait was seen. These data suggest that the open gastrocnemius recession procedure has low associated morbidity.  相似文献   
994.
OBJECTIVE: Alveolar distraction is a relatively novel procedure by which alveolar bone and underlying mucosa are regenerated. The low predictability of other vertical or horizontal bone regeneration methods has increased interest in this promising technique. This article was designed to review published clinical and experimental results on alveolar distraction, including basic research in other disciplines (maxillofacial and orthopedic distraction) related to or with influence on alveolar distraction. STUDY DESIGN: A review of the international literature was performed to summarize results of clinical and experimental studies on alveolar distraction and on distraction at other anatomical sites that contribute important findings on tissue biology, molecular mechanisms, and other factors that influence and participate in the alveolar distraction process. RESULTS: Research into alveolar distraction has addressed the latency phase, distraction phase, and consolidation phase, yielding highly variable results. Little experimental research has been carried out on this procedure, and most publications are clinical studies with a short follow-up period. Published studies have reported a high rate of complications, attributable to our current lack of understanding of the process. CONCLUSIONS: Definitive conclusions on alveolar distraction are hampered by the lack of clinical and experimental studies to date. Greater knowledge of the factors that influence the distraction process will lead to a more predictable and efficacious distraction technique and a better distractor design.  相似文献   
995.
996.
997.
Background: Few studies have examined the use of ultrasound for sciatic nerve localization. The authors evaluated the usefulness of low-frequency ultrasound in identifying the sciatic nerve at three locations in the lower extremity and in guiding needle advancement to target before nerve stimulation.

Methods: In this prospective observational study, 15 volunteers underwent sciatic nerve examination using a curved ultrasound probe in the range of 2-5 MHz and a Philips-ATL 5000 unit (ATL Ultrasound, Bothell, WA) in the gluteal, infragluteal, and proximal thigh regions. Thereafter, an insulated block needle was advanced inline with the ultrasound beam to reach the nerve target, which was further confirmed by electrical stimulation. The quality of sciatic nerve images, ease of needle to nerve contact, threshold stimulating current, and resultant motor response were recorded.

Results: The sciatic nerve was successfully identified in the transverse view as a solitary predominantly hyperechoic structure on ultrasound in all of the three regions examined. The target nerve was visualized easily in 87% and localized within two needle attempts in all patients. Nerve stimulation was successful in 100% after two attempts with a threshold current of 0.42 +/- 0.12 (mean +/- SD) eliciting foot plantarflexion or dorsiflexion.  相似文献   

998.
999.
Antenatal corticosteroid therapy to enhance fetal lung maturation in pregnancies at risk for preterm delivery is used commonly, based on the assumption that its established benefits outweigh associated risks. Corticosteroid treatment does confer some risks, particularly with respect to restricted brain growth and disordered neuronal development. These alterations have the potential for long-term effects on health. They deserve further study, and should not be undervalued. Corticosteroid therapy should be applied selectively in those situations in which the risk of preterm birth is very high and the likelihood of severe respiratory distress syndrome substantial.  相似文献   
1000.
Infections due to Penicillium species other than P.marneffei are rare. We identified a boy with X-linked chronic granulomatous disease (X-CGD) with a pulmonary nodule and adjacent rib osteomyelitis caused by Penicillium piceum. The only sign of infection was an elevated sedimentation rate. P. piceum was isolated by fine needle aspirate and from excised infected tissues. Surgical removal and one year of voriconazole treatment were very well tolerated and led to complete recovery. Microbiological, microscopic and molecular studies support the fungal diagnosis. P. piceum should be considered as a relevant pathogen in immunocompromised 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