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   11419篇
  免费   923篇
  国内免费   23篇
耳鼻咽喉   195篇
儿科学   446篇
妇产科学   283篇
基础医学   1413篇
口腔科学   261篇
临床医学   1154篇
内科学   2669篇
皮肤病学   143篇
神经病学   1233篇
特种医学   712篇
外科学   1321篇
综合类   234篇
一般理论   65篇
预防医学   827篇
眼科学   120篇
药学   511篇
  1篇
中国医学   2篇
肿瘤学   775篇
  2021年   112篇
  2019年   125篇
  2018年   129篇
  2017年   99篇
  2016年   103篇
  2015年   119篇
  2014年   161篇
  2013年   263篇
  2012年   418篇
  2011年   394篇
  2010年   227篇
  2009年   198篇
  2008年   433篇
  2007年   450篇
  2006年   439篇
  2005年   431篇
  2004年   386篇
  2003年   401篇
  2002年   379篇
  2001年   403篇
  2000年   383篇
  1999年   338篇
  1998年   125篇
  1997年   130篇
  1996年   135篇
  1995年   135篇
  1994年   108篇
  1993年   130篇
  1992年   318篇
  1991年   313篇
  1990年   281篇
  1989年   327篇
  1988年   294篇
  1987年   335篇
  1986年   339篇
  1985年   299篇
  1984年   208篇
  1983年   235篇
  1982年   176篇
  1981年   133篇
  1980年   152篇
  1979年   209篇
  1978年   145篇
  1977年   108篇
  1976年   109篇
  1975年   107篇
  1974年   104篇
  1973年   116篇
  1972年   96篇
  1970年   94篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Background: This study examines the notion that gastrointestinal endoscopy performed by supervised surgical residents is safe. Methods: We reviewed all gastrointestinal endoscopic procedures performed by surgical residents with faculty supervision for complications and deaths occurring up to 30 days following the procedures. Results: The overall complication rate for 9,201 upper and lower endoscopy procedures was 1.4% and 0.42%, respectively. Overall mortality rate was 0.76% for upper endoscopy and 0.6% for lower endoscopy. No mortality was a direct result of a procedure-related complication. Intestinal perforation, drug overdose, bleeding, and aspiration were the most common procedure-related complications. Each resident completed an average of 75 upper endoscopies and 79 lower endoscopies during their training period. Conclusions: Gastrointestinal endoscopy can be performed safely by surgical residents with appropriate supervision. The higher morbidity and mortality of upper endoscopy are most likely related to the underlying disease rather than the procedure. Awareness of common complications and application of appropriate precautions and instruction are critical for minimizing complications. Received 25 March 1996/Accepted: 24 April 1996  相似文献   
72.
We report a patient with metastatic thyroid carcinoma invading the esophagus in whom barium and MR examinations revealed an expansile intraluminal mass indistinguishable from that of a primary esophageal malignancy. Metastatic thyroid carcinoma should therefore be included in the differential diagnosis of an expansile esophageal mass. As in our patient, MR imaging may be useful for showing that the mass originates in the thyroid gland.  相似文献   
73.
Intestinal obstruction proximal to a transition zone without an interposed physical barrier usually indicates Hirschsprung disease. The authors report one case of focal small bowel muscular thinning just distal to a transition zone that produced clinical and radiographic findings that simulated long-segment Hirschsprung disease in a 2-day-old infant.  相似文献   
74.
Fatality resulting from methylphenidate overdose   总被引:1,自引:0,他引:1  
A case involving an accidental overdose fatality resulting from an intravenous injection of crushed Ritalin (methylphenidate) tablets is presented. The drug was quantified by gas chromatography/nitrogen-phosphorus detection and confirmed by gas chromatography/mass spectrometry. Concentrations of drug were as follows: blood, 2.8 mg/L; bile, 5.7 mg/L; kidney, 3.0 mg/kg; liver, 2.1 mg/kg; and stomach contents, 1.6 mg total. Other drugs and volatile substances were not detected.  相似文献   
75.
Inositol is an important precursor for second messenger synthesis and has been reported to be reduced by lithium treatment in rat brain and in human CSF in depression. An open trial of 6 g/day in 11 depressed patients resistant to previous treatment led to major improvement in nine patients. The enzyme synthesizing inositol has been reported to be elevated in schizophrenia, suggesting an attempted compensation for possible inositol deficiency. A controlled double-blind crossover trial in 10 chronic schizophrenic patients of 6 g/day of inositol for 30 days did not reveal any benefit.  相似文献   
76.
Salmonella typhi Ty21a vaccine in a liquid formulation was evaluated in 634 Thai children 2 to 6 years of age. The seroconversion rate was 69% for those who received vaccine versus 14% for those who received placebo (P < 0.005). The immune responses among vaccine recipients ranged from 60% in 3-year-olds to 81% for 6-year-olds.  相似文献   
77.
78.
79.
N Weidner  J D Levine 《Cancer》1988,62(8):1561-1567
Two patients developed nodular, well-circumscribed tumors of the breast, discovered by mammography. They were fibroadenoma-like by gross examination and biphasic by light microscopy, containing both tubular glands and spindled myoid cells. Immunocytochemical studies revealed cytokeratin and S-100 immunoreactivity in both the spindled myoid cells and in the tubuloglandular cells (S-100 was focal in the latter). In addition, the spindled myoid cells were immunoreactive for vimentin but negative for desmin. Ultrastructural studies showed the tubular glands to be composed of luminal epithelial cells focally surrounded by myoepithelial cells, but the stroma contained spindled myoepithelial cells admixed with occasional fibroblasts. The diagnostic term, "adenomyoepithelioma," is appropriate for biphasic tumors having both glandular and myoepitheliomatous differentiation. Although additional experience is necessary to be conclusive regarding the biologic behavior of these unusual lesions, the authors believe the adenomyoepitheliomas described here are benign. They were well circumscribed without invasion of adjacent breast, contained neither mitotic figures nor cytologic atypia, and have not recurred or metastasized (6 and 10 months after removal).  相似文献   
80.
Doppler ultrasound is currently being widely applied to measure intracardiac pressure gradients noninvasively. In comparative invasive studies, it is generally assumed that pressure is effectively uniform distal to the stenosis. As the poststenotic jet expands, however, its velocity decreases, and pressure is recovered to the extent permitted by turbulence, so that the measured gradient will be lower if the distal catheter is positioned downstream from the vena contracta. This can lead to apparent Doppler "overestimation" of the pressure gradient because of this phenomenon of pressure recovery. This study demonstrates that pressure recovery can be important in a variety of clinical settings studied by in vitro models. Although most prominent in streamlined tunnels modeled after the obstruction in patients with hypertrophic cardiomyopathy, these effects are important even for central stenoses at physiologic flow rates. Because precise catheter position is not always known or controlled, these findings suggest an important advantage for Doppler gradient estimation, because it provides the maximal gradient at the vena contracta, which determines the load on the proximal chamber.  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