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   3787篇
  免费   427篇
  国内免费   19篇
耳鼻咽喉   75篇
儿科学   96篇
妇产科学   53篇
基础医学   402篇
口腔科学   60篇
临床医学   404篇
内科学   725篇
皮肤病学   53篇
神经病学   378篇
特种医学   181篇
外科学   586篇
综合类   162篇
现状与发展   20篇
一般理论   1篇
预防医学   460篇
眼科学   92篇
药学   145篇
中国医学   3篇
肿瘤学   337篇
  2023年   50篇
  2022年   17篇
  2021年   59篇
  2020年   50篇
  2019年   64篇
  2018年   108篇
  2017年   82篇
  2016年   82篇
  2015年   86篇
  2014年   111篇
  2013年   179篇
  2012年   201篇
  2011年   193篇
  2010年   149篇
  2009年   146篇
  2008年   172篇
  2007年   175篇
  2006年   176篇
  2005年   145篇
  2004年   156篇
  2003年   138篇
  2002年   142篇
  2001年   132篇
  2000年   103篇
  1999年   93篇
  1998年   64篇
  1997年   58篇
  1996年   77篇
  1995年   51篇
  1994年   41篇
  1993年   47篇
  1992年   55篇
  1991年   61篇
  1990年   70篇
  1989年   71篇
  1988年   50篇
  1987年   53篇
  1986年   62篇
  1985年   54篇
  1984年   33篇
  1983年   42篇
  1982年   25篇
  1980年   22篇
  1979年   27篇
  1978年   22篇
  1977年   25篇
  1975年   16篇
  1974年   20篇
  1973年   24篇
  1971年   17篇
排序方式: 共有4233条查询结果,搜索用时 15 毫秒
1.
2.
3.
BACKGROUND: Endothelin, a peptide with strong vasoconstrictive and mitogenic properties, has been found to increase after cardiac transplantation. We therefore assessed the association between its precursor peptide, big endothelin-1, and intimal hyperplasia and coronary flow reserve after heart transplantation. METHODS: Thirty-five patients without hemodynamically significant coronary artery disease after heart transplantation were investigated: Average peak flow velocity in the left anterior descending artery (LAD) was assessed by intracoronary Doppler at baseline as well as after injection of adenosine; coronary flow reserve was calculated as a ratio of both and was corrected for patient age and baseline average peak flow velocity. Lumen, intima + media and total vessel area were measured by intracoronary ultrasound. The plasma concentration of big endothelin-1 in venous blood was determined by radioimmunoassay. RESULTS: Patients with elevated big endothelin-1 levels (>2 fmol/ml) tended to have a decreased corrected coronary flow reserve (2.60 +/- 0.9 vs 3.21 +/- 1.0, p = 0.078). They also had a significantly larger intima + media area (5.82 +/- 2.9 vs 2.37 +/- 2.9 mm(2), p = 0.004) and total vessel area (18.36 +/- 5.8 vs 12.81 +/- 4.8 mm(2), p = 0.012) than those with normal plasma concentrations. CONCLUSIONS: Our study suggests an association between elevated big endothelin-1 plasma levels and the development of intimal hyperplasia and reduction of coronary flow reserve after cardiac transplantation.  相似文献   
4.
Eight lymphatic fluid collections were drained percutaneously. There were no immediate or late complications. Seven patients had follow-up; 1 required surgical drainage of a residual or recurrent lymphocele, and another had reaccumulated fluid in a lymphocele which was detected on autopsy. The remaining lymphatic collections responded to percutaneous drainage. Percutaneous drainage is safe and can be an effective tool in the management of lymphatic collections.  相似文献   
5.
Information on the relative incidence of Crohn's disease and ulcerative colitis was obtained by a prospective investigation at six Melbourne teaching hospitals. One hundred and eleven patients who presented with chronic inflammatory bowel diseases between 1980-1981 were admitted to the study. Forty (36%) patients were diagnosed as having Crohn's disease and 63 (57%) patients as having ulcerative colitis. The type of chronic inflammatory bowel disease could not be determined in eight (7%) patients. These findings suggest that the relative frequency of Crohn's disease and ulcerative colitis in Melbourne hospitals is within the range that is reported for northern Europe and the United States.  相似文献   
6.
7.
Deep granuloma annulare (DGA) is one of several lesions of skin and superficial soft tissues whose histologic character is a palisading granuloma with a small central focus of necrosis or necrobiosis. Unlike the other palisading necrobiotic lesions, DGA has a predilection for children in the first 5 to 6 years of life. A painless subcutaneous nodule(s) in the lower anterior tibial region or foot and the scalp, typically in the occiput, was the most common presenting feature in this study of 35 cases. Additional or recurrent lesions were reported in approximately 70% of cases with clinical follow-up. All lesions showed the presence of necrobiosis; however, one of the characteristic features was the multinodular character of the predominantly mononuclear cellular aggregates. The presence of vascular spaces at the periphery of the nodular profiles served as a clue to the diagnosis of DGA. The palisading arrangement of the mononuclear cells was evident only in those foci with central necrobiosis. A histiocytic disorder or fibrohistiocytic process was a common consideration in the differential diagnosis, especially in those cases with less apparent foci of necrosis. Palisading histiocytes with prominent eosinophilic cytoplasm and some nuclear atypism were problematic with regard to possible epithelioid sarcoma. Our study failed to identify any underlying or predisposing factors in the development of DGA. Despite the fact that DGA is a well-documented lesion in children, it occurs sufficiently infrequently that it is often not considered clinically when it presents as a subcutaneous mass or masses in a child. Its recognition by the pathologist is especially important as the occurrence of additional lesions in a high proportion of children can be anticipated without undue concern. Received June 16, 1997; accepted October 28, 1997.  相似文献   
8.
9.
Frequency of symptoms of depression and selected health-related practices and events were measured in a sample of 219 high school students. Students reported numerous symptoms of depression. Relative proportions of boys and girls reporting symptoms of depression were not significantly different. However, girls reported experiencing more severe depression than their male counterparts. Depression correlated significantly with several of the 22 health practices and states of affect examined. Both the determinants and manifestations of depression in adolescent cohorts require in-depth investigation. Possible implications for school health personnel are discussed.  相似文献   
10.
The visit of Dr. Trendley Dean to Dublin in the mid-1950s helped accelerate the decision to introduce water fluoridation as a public health measure in the prevention of caries in the Republic of Ireland. A challenge to the constitutional validity of the Health (Fluoridation of Water Supplies) Act 1960 failed and in 1964 the water supplies of Dublin city were fluoridated. Over the next seven to eight years all the major urban communities in the Republic of Ireland were fluoridated. Currently, 67 percent of the 3.5 million people in the country reside in fluoridated communities. Studies conducted over the last 20 years show that residents of fluoridated communities have better dental health than those in nonfluoridated communities—the mean dmft is lower in children and the number of natural teeth present in adults is higher.  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