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   1013574篇
  免费   100462篇
  国内免费   4107篇
耳鼻咽喉   17713篇
儿科学   29900篇
妇产科学   27434篇
基础医学   128428篇
口腔科学   27040篇
临床医学   101680篇
内科学   210535篇
皮肤病学   24320篇
神经病学   85018篇
特种医学   41546篇
外国民族医学   178篇
外科学   176402篇
综合类   24970篇
现状与发展   74篇
一般理论   272篇
预防医学   74528篇
眼科学   23828篇
药学   66218篇
  1篇
中国医学   1620篇
肿瘤学   56438篇
  2020年   8918篇
  2018年   14489篇
  2017年   12816篇
  2016年   14539篇
  2015年   15816篇
  2014年   26016篇
  2013年   31874篇
  2012年   28530篇
  2011年   29729篇
  2010年   23986篇
  2009年   26821篇
  2008年   28725篇
  2007年   29206篇
  2006年   31351篇
  2005年   28381篇
  2004年   27196篇
  2003年   25315篇
  2002年   24472篇
  2001年   39546篇
  2000年   39423篇
  1999年   34026篇
  1998年   12678篇
  1997年   11842篇
  1996年   11646篇
  1995年   11040篇
  1994年   9577篇
  1993年   8731篇
  1992年   28033篇
  1991年   27488篇
  1990年   26717篇
  1989年   25833篇
  1988年   24224篇
  1987年   23744篇
  1986年   22618篇
  1985年   21827篇
  1984年   16921篇
  1983年   14512篇
  1982年   9341篇
  1979年   17057篇
  1978年   12444篇
  1977年   10566篇
  1976年   9567篇
  1975年   10414篇
  1974年   12877篇
  1973年   12367篇
  1972年   11834篇
  1971年   10888篇
  1970年   10460篇
  1969年   9998篇
  1968年   8932篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
This study examines the relationships between patient characteristics and surrogate decision maker characteristics on surrogates' preferences for life-sustaining treatments. Caucasian and African-American caregivers and noncaregivers (n=110) responded to a vignette involving a medical crisis in a hospitalized older man who suffered cardiac arrest, one of the most common causes of death among older Americans. This man was described as either a cognitively intact or moderately demented family member. Participants made decisions regarding cardiopulmonary resuscitation (CPR), CPR and ventilation, and CPR and tube feeding. Analyses followed a 2 (cognitive status) 2 (caregiving status) 2 (racial background) analysis of covariance design, with education and income used as covariates. In general, participants were less likely to initiate life-sustaining treatments in demented patients. Caucasian caregivers were less likely to initiate CPR and ventilation and CPR and tube feeding. Results indicate that characteristics of the patient and the interplay between cultural issues and experience with caregiving affect surrogate judgements regarding life-sustaining treatments.  相似文献   
43.
The value of ultrasound in the diagnosis of a large rapidly growing thyroid mass was assessed in a study of 42 patients with a large (> 3 cm) rapidly growing (< two months) solitary mass. Haemorrhage into a thyroid nodule was present in 31 patients and thyroid malignancy in 11. Ultrasound of haemorrhage into a thyroid nodule revealed a large cystic mass in all 31 patients containing internal debris (22), septations (three), or a combination of both (six). The malignant causes of a large rapidly growing mass were lymphoma (two), anaplastic carcinoma (four) and metastasis (five). Ultrasound of these thyroid malignancies revealed a mass with a smooth, well-defined margin and strikingly low homogeneous echogenicity in all cases. Patients with thyroid metastases had evidence of widespread metastatic disease elsewhere. Lymphoma was differentiated from anaplastic carcinoma on fine-needle aspiration cytology or surgical biopsy. Ultrasound was of value in differentiating between a benign haemorrhagic nodule and a malignant tumour. The various malignant tumours had similar appearances, however, and could not be distinguished on ultrasound.  相似文献   
44.
Low signal intensity on long-repetition-time MR sequences has been observed in deep gray matter structures in patients with multiple sclerosis. This T2 shortening most likely represents a nonspecific degenerative process. We recently observed T2 shortening in the pericentral cortical gray matter and subcortical white matter in a patient with severe multiple sclerosis and we postulate that this represents an additional manifestation of neural degeneration.  相似文献   
45.
46.
Precise and limited decompression for lumbar spinal stenosis   总被引:3,自引:0,他引:3  
Summary Fifty-eight consecutive patients with lumbosacral nerve root entrapment due to spinal stenosis were treated with modified microsurgical decompression. Only the clinically relevant sides and levels were decompressed while the spinous processes, the interspinous ligaments, the medial portion of ligamentum flavum and the functionally important parts of the facet joints were preserved. The reviewers rated recovery as good or excellent in 71% of patients while patient self-assessment indicated 76% good or excellent outcome. These data suggest that microsurgical decompression of spondyloarthritic changes can effectively relieve the signs and symptoms of nerve root compression and that with careful evaluation of all available data the number of nerve roots requiring decomperession is often fewer than what is suggested by diagnositic images alone.  相似文献   
47.
48.
Adverse ocular effects associated with niacin therapy.   总被引:2,自引:0,他引:2       下载免费PDF全文
In a retrospective survey of patients taking medication for hyperlipidaemia, those taking niacin (nicotinic acid) were more likely (p < 0.05) to report sicca syndromes, blurred vision, eyelid oedema, and macular oedema compared with those who never took niacin. Additionally, 7% of those taking niacin discontinued the drug owing to adverse ocular side effects, while none of the other lipid lowering agents were found to cause these side effects (p = 0.016). Data from spontaneous reporting systems support a possible association of decreased vision, cystoid macular oedema, sicca-like symptoms, discoloration of the eyelids with or without periorbital or eyelid oedema, proptosis, loss of eyebrow or eyelashes, and superficial punctate keratitis with the use of niacin in high doses. Decreased vision may be marked, and if the drug is not discontinued, may progress to cystoid macular oedema. All ocular side effects listed above are reversible if the association with niacin is recognised and the drug is discontinued; both the incidence and severity of the ocular side effects seem to be dose dependent.  相似文献   
49.
50.
In 41 patients with recurrent sustained ventricular tachycardia and/or ventricular fibrillation an integrated pacemaker-defibrillator-system (PCD, Medtronic, model 7216 A or 7217 B) was implanted. In 21 out of 24 (88%) patients a new transvenous implantation technique in combination with a subcutaneous patch electrode was used. The implanted devices comprise antibradycardiac pacemaker functions, two different forms of antitachycardiac pacemaker functions (ramp and burst pacing), and internal cardioversion or defibrillation capabilities. During a mean follow-up of 8 months 147 episodes of ventricular tachycardia were detected, 131 of them were terminated successfully by antitachycardiac pacing; in 13 episodes internal cardioversion was applied to revert ventricular tachycardia. Twenty-seven episodes of ventricular fibrillation or rapid ventricular tachycardia (greater than 200/min) were detected and successfully terminated by internal defibrillation. In six patients with intermittent rapid atrial fibrillation, change of antiarrhythmic therapy was required to avoid activation of the device. The new integrated pacemaker-defibrillator systems improve therapy in patients with life-threatening tachyarrhythmias by reducing the number of internal cardioversions/defibrillations; the non-thoracotomy approach reduces the post operative risk.  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