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   2627015篇
  免费   187260篇
  国内免费   7838篇
耳鼻咽喉   34740篇
儿科学   85988篇
妇产科学   71956篇
基础医学   368342篇
口腔科学   70712篇
临床医学   237125篇
内科学   526000篇
皮肤病学   63363篇
神经病学   216818篇
特种医学   101507篇
外国民族医学   737篇
外科学   392829篇
综合类   50548篇
现状与发展   5篇
一般理论   976篇
预防医学   197204篇
眼科学   57660篇
药学   190387篇
  9篇
中国医学   5427篇
肿瘤学   149780篇
  2021年   20991篇
  2019年   21391篇
  2018年   30182篇
  2017年   23339篇
  2016年   27134篇
  2015年   30406篇
  2014年   41637篇
  2013年   61859篇
  2012年   82615篇
  2011年   87066篇
  2010年   52545篇
  2009年   50366篇
  2008年   81138篇
  2007年   86276篇
  2006年   87821篇
  2005年   83939篇
  2004年   80897篇
  2003年   78068篇
  2002年   75419篇
  2001年   129148篇
  2000年   132021篇
  1999年   111182篇
  1998年   31745篇
  1997年   28348篇
  1996年   28621篇
  1995年   27689篇
  1994年   25368篇
  1993年   23687篇
  1992年   85648篇
  1991年   81973篇
  1990年   79198篇
  1989年   76491篇
  1988年   69827篇
  1987年   68344篇
  1986年   63854篇
  1985年   60807篇
  1984年   45153篇
  1983年   38137篇
  1982年   22542篇
  1981年   20080篇
  1979年   39113篇
  1978年   27549篇
  1977年   23367篇
  1976年   21580篇
  1975年   22888篇
  1974年   26891篇
  1973年   25455篇
  1972年   23850篇
  1971年   22069篇
  1970年   20268篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
STUDY OBJECTIVE: To evaluate the hemodynamic effects of the antiarrhythmic drug, encainide, in patients with severe chronic heart failure. DESIGN: Unblinded, before-after study. SETTING: Referral center for patients with heart failure. PATIENTS: Thirty patients with severe chronic heart failure and a left ventricular ejection fraction less than 40%. INTERVENTIONS: Invasive hemodynamic measurements were done (using a balloon-tipped thermodilution catheter) before and for 3 hours after a single oral dose of 50 mg of encainide. MEASUREMENTS AND MAIN RESULTS: Ninety to one hundred and twenty minutes after its administration, encainide produced a significant deterioration in cardiac performance, as reflected by a fall in cardiac index from 2.3 to 1.8 L/min.m2 body surface (mean change 0.5 +/- 0.1; P less than 0.001), a fall in stroke work index from 26 to 18 g.m/m2 (mean change 8 +/- 2; P less than 0.001), and an increase in left ventricular filling pressure from 19 to 22 mm Hg (mean change 3 +/- 2; P less than 0.05). These deleterious hemodynamic effects were accompanied by worsening symptoms of heart failure in 8 of the 30 patients. Serum levels of encainide and its metabolites, O-desmethylencainide and 3-methoxy-O-desmethylencainide, were within the therapeutic range in most patients. CONCLUSIONS: Encainide can cause adverse hemodynamic and clinical effects in patients with severe chronic heart failure.  相似文献   
992.
Lesions typical of subacute cutaneous lupus erythematosus developed in an elderly woman after 6 months of PUVA (8-methoxypsoralen and longwave ultraviolet light) therapy for psoriasis. Pancytopenia, antibodies to double-stranded DNA, and hypocomplementemia developed concurrently with the appearance of the cutaneous lesions. With discontinuation of photochemotherapy, the cutaneous lesions disappeared and the pancytopenia improved.  相似文献   
993.
A 37-year-old woman receiving long-term hemodialysis was admitted to the hospital with a fever of unknown origin (6 weeks of unexplained, persistent, low-grade fever). Although she had received vancomycin hydrochloride 5 days before the onset of fever, the drug was not suspected as the cause because of the duration of fever, the administration of vancomycin on prior occasions without incident, and the lack of allergic stigmata. After hospitalization, vancomycin and gentamicin sulfate were administered empirically. Immediately thereafter, her temperature rose to 40 degrees C, and over the ensuing 24 hours, eosinophilia and a maculopapular rash developed that resolved entirely when antibiotic therapy was stopped and low-dose steroid therapy was instituted. The prolonged hypersensitivity reaction after a single dose of vancomycin is consistent with the greatly extended half-life of this drug in the population with end-stage renal disease and should alert physicians to the possibility of such persistent idiosyncratic reactions in this group.  相似文献   
994.
Retrosternal dislocations of the clavicle have been reported previously in adults throughout the orthopedic literature. However, in children few cases have been noted in either the pediatric, emergency, or orthopedic literature. The potential for great vessel injury as well as acute airway compromise makes the retrosternal disruption of the sternoclavicular joint a surgical emergency that must be diagnosed quickly. Diagnosis is enhanced by the cephalic tilt view and by computed tomography (CT scan), as planar x-ray and tomography do not always reveal this potentially life-threatening condition. Surgical consultation must be sought acutely; however, management may need to begin prior to definitive repair. Emergency management begins by suspecting the injury, and with immediate airway and circulatory support for the patient.  相似文献   
995.
The process of data entry and initial analysis to locate data errors is described. Basic terms are defined and a simple method of entering data by using word processing software is illustrated. Data checking is done by using visual check of the raw data. Statistical programs are then used to locate possible data errors by finding data points (outliers) that are very different from the average. Special graphic output of statistical programs, scatterplots and box and whisker plots can be used to further locate questionable data. Examples of data entry forms and annotated step by step data cleaning with the use of inexpensive programs for personal computers are presented.  相似文献   
996.
997.
Synovial fluid phospholipase A2s and inflammation.   总被引:1,自引:1,他引:0       下载免费PDF全文
The activation of phospholipase A2 is believed to have an important role in the inflammatory process owing to its induction of eicosanoids, platelet activating factor, and other mediators. Soluble phospholipase A2 has been associated with exudates in different inflammatory conditions. In this review the general physiology and control of this enzyme and, in particular, the most recent findings on human synovial fluid phospholipase A2s are discussed.  相似文献   
998.
A variety of nutritional factors influence the bioavailability of calcium and increase a woman's risk of osteoporosis. Eight healthy women completed an 8-week metabolic study designed to investigate the effect of nonalcoholic carbonated beverage consumption on calcium metabolism. Compared with women receiving a control diet, women consuming a diet high in nonalcoholic carbonated beverages demonstrated similar mean serum levels of calcium, ionized calcium, phosphorus, alkaline phosphatase, parathyroid hormone, 1,25-dihydroxyvitamin D3, and osteocalcin. Twenty-four-hour urine volume, creatinine clearance, calcium-creatinine ratio, and phosphorus-creatinine ratio were similar during consumption of the diet high in nonalcoholic carbonated beverages and the control diet. Twenty-four-hour cyclic adenosine monophosphate-creatinine ratio was significantly lower in women consuming the diet high in nonalcoholic carbonated beverage compared with women receiving the control diet (342 +/- 27.4 nmol/mmol vs 409 +/- 22.1 nmol/mmol). Consumption of a diet high in nonalcoholic carbonated beverages on a short-term basis does not appear to affect adversely the serum or urinary markers of calcium metabolism.  相似文献   
999.
1000.
This study was conducted to test the effects of preadmission preparation on parent and child psychological upset at the time of tonsillectomy surgery, on child postsurgery behavior, and on parental compliance with home care instructions. Forty children aged 3 to 11 years who underwent tonsillectomy on an outpatient basis were studied. No significant differences were found in parent and child behaviors of those people in the preparation group compared with those in the nonpreparation group. Parental reports of home care revealed that the majority of parents did not follow at least one half of the physicians' home care instructions. The findings of the study indicate the need to further examine factors associated with parental compliance with home care instructions.  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