全文获取类型
收费全文 | 3177篇 |
免费 | 354篇 |
国内免费 | 25篇 |
专业分类
耳鼻咽喉 | 60篇 |
儿科学 | 105篇 |
妇产科学 | 56篇 |
基础医学 | 502篇 |
口腔科学 | 84篇 |
临床医学 | 406篇 |
内科学 | 624篇 |
皮肤病学 | 64篇 |
神经病学 | 170篇 |
特种医学 | 253篇 |
外科学 | 346篇 |
综合类 | 129篇 |
一般理论 | 4篇 |
预防医学 | 323篇 |
眼科学 | 54篇 |
药学 | 235篇 |
肿瘤学 | 141篇 |
出版年
2021年 | 22篇 |
2019年 | 33篇 |
2018年 | 43篇 |
2017年 | 43篇 |
2016年 | 53篇 |
2015年 | 57篇 |
2014年 | 71篇 |
2013年 | 92篇 |
2012年 | 139篇 |
2011年 | 138篇 |
2010年 | 85篇 |
2009年 | 85篇 |
2008年 | 134篇 |
2007年 | 111篇 |
2006年 | 120篇 |
2005年 | 128篇 |
2004年 | 113篇 |
2003年 | 95篇 |
2002年 | 106篇 |
2001年 | 72篇 |
2000年 | 94篇 |
1999年 | 84篇 |
1998年 | 71篇 |
1997年 | 70篇 |
1996年 | 65篇 |
1995年 | 64篇 |
1994年 | 38篇 |
1993年 | 60篇 |
1992年 | 68篇 |
1991年 | 63篇 |
1990年 | 59篇 |
1989年 | 72篇 |
1988年 | 83篇 |
1987年 | 99篇 |
1986年 | 89篇 |
1985年 | 54篇 |
1984年 | 56篇 |
1983年 | 55篇 |
1982年 | 35篇 |
1981年 | 40篇 |
1980年 | 35篇 |
1979年 | 32篇 |
1978年 | 31篇 |
1976年 | 27篇 |
1975年 | 20篇 |
1972年 | 29篇 |
1971年 | 20篇 |
1970年 | 24篇 |
1969年 | 22篇 |
1967年 | 21篇 |
排序方式: 共有3556条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
During a 12-month period 115 patients with abnormal mammograms had stereotaxic needle localization and biopsy of nonpalpable breast lesions. The procedure was performed on a Fischer Mammotest II machine (Fischer Imaging; Denver, CO) and the biopsies were taken with a #18 gauge Bard biopsy needle using a Bard biopty gun (distributed by Bard Urological; Covington, GA; manufactured by Radiplast; Uppsala, Sweden). Mammographic lesions were suspicious matrix densities (85), clustered microcalcifications (22), or a combination of both (8). The pathologist recommended open biopsy in 16 per cent (18/115) of the patients. Pathology on the 18 open biopsies revealed that 11 (9 matrix densities and 2 calcifications) were carcinomas and true positives, whereas the other 7 (all matrix densities) were benign mastopathies and false positives. Further analysis of the pathologic data showed that there were three possible diagnoses from the needle biopsies on the patients that later went to open biopsy: cancer (6), very suspicious lesion (9), and slightly suspicious lesion without atypical hyperplasia (3). All 6 cancers were confirmed by open biopsy; about half (5/9) of the very suspicious lesions were cancer and none (0/3) of the slightly suspicious lesions were cancer. More cases, followed by open biopsy, are needed to refine the selection procedure for open biopsy and careful follow-up of the patients who did not have open biopsy will also be needed to determine the false negative rate. Excellent patient acceptance was found and the test was easy to perform in the office without serious complications. Furthermore, the test was cost effective because it avoided open biopsy in 97 patients. 相似文献
7.
8.
Factors affecting breastfeeding among women of Mexican origin or descent in Los Angeles. 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《American journal of public health》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Data on breastfeeding intentions and behavior were collected in prenatal and postpartum interviews as part of a study on first birth among 518 women of Mexican origin or descent in two Los Angeles hospitals. The prenatal intentions of 82 per cent of the women to breastfeed were maintained postpartum in one hospital but dropped sharply in the other. A greater number of hours a day with the baby in the hospital and earlier initiation of breastfeeding were associated with the hospital where prenatal breastfeeding intentions were more likely to be carried out. The intention to work postpartum was associated both with the decision not to breastfeed at all and with shorter intended duration of breastfeeding. 相似文献
9.
Ralls PW; Johnson MB; Kanel G; Dobalian DM; Colletti PM; Boswell WD Jr; Radin DR; Halls JM 《Radiology》1986,161(2):451-454
FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease. 相似文献
10.