全文获取类型
收费全文 | 22056篇 |
免费 | 1291篇 |
国内免费 | 61篇 |
专业分类
耳鼻咽喉 | 329篇 |
儿科学 | 598篇 |
妇产科学 | 461篇 |
基础医学 | 3011篇 |
口腔科学 | 453篇 |
临床医学 | 2016篇 |
内科学 | 5077篇 |
皮肤病学 | 244篇 |
神经病学 | 2046篇 |
特种医学 | 648篇 |
外科学 | 3426篇 |
综合类 | 302篇 |
一般理论 | 16篇 |
预防医学 | 1635篇 |
眼科学 | 589篇 |
药学 | 1169篇 |
3篇 | |
中国医学 | 39篇 |
肿瘤学 | 1346篇 |
出版年
2024年 | 148篇 |
2023年 | 209篇 |
2022年 | 402篇 |
2021年 | 796篇 |
2020年 | 437篇 |
2019年 | 636篇 |
2018年 | 743篇 |
2017年 | 483篇 |
2016年 | 497篇 |
2015年 | 607篇 |
2014年 | 787篇 |
2013年 | 1038篇 |
2012年 | 1503篇 |
2011年 | 1525篇 |
2010年 | 830篇 |
2009年 | 708篇 |
2008年 | 1252篇 |
2007年 | 1235篇 |
2006年 | 1222篇 |
2005年 | 1154篇 |
2004年 | 1064篇 |
2003年 | 933篇 |
2002年 | 922篇 |
2001年 | 151篇 |
2000年 | 137篇 |
1999年 | 165篇 |
1998年 | 180篇 |
1997年 | 165篇 |
1996年 | 137篇 |
1995年 | 126篇 |
1994年 | 117篇 |
1993年 | 113篇 |
1992年 | 107篇 |
1991年 | 102篇 |
1990年 | 110篇 |
1989年 | 90篇 |
1988年 | 106篇 |
1987年 | 113篇 |
1986年 | 76篇 |
1985年 | 105篇 |
1984年 | 106篇 |
1983年 | 101篇 |
1982年 | 135篇 |
1981年 | 125篇 |
1980年 | 164篇 |
1979年 | 77篇 |
1978年 | 87篇 |
1977年 | 79篇 |
1976年 | 84篇 |
1974年 | 71篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
V. Leroy Young Mary K. Seaton Christine A. Feely Cynthia Arfken Dorothy F. Edwards Carolyn M. Baum Samuel Logan 《American journal of industrial medicine》1995,27(3):419-431
On-site testing of 157 poultry processors disclosed that 50% had three or more abnormal upper extremity findings out of a total of 22 possibles. The average worker had five to six abnormal findings. Impaired pinch strength, decreased vibration sensitivity in the fingertips, and reports of current numbness were the most prevalent. Of workers with signs, 25% reported no symptoms, whereas only 8% of workers reported symptoms but had no signs. The investigators concluded that this measurement method has utility for assessments of worker populations to determine prevalence of CTDs and, potentially, for preclinical detection of these disorders to permit early intervention, reduce medical costs, and minimize disability. The need for accurate measurement to enhance early detection and prevention is discussed. 相似文献
23.
24.
We have earlier introduced a principle for learning metrics, which shows how metric-based methods can be made to focus on discriminative properties of data. The main applications are in supervising unsupervised learning to model interesting variation in data, instead of modeling all variation as plain unsupervised learning does. The metrics are derived by approximations to an information-geometric formulation. In this paper, we review the theory, introduce better approximations to the distances, and show how to apply them in two different kinds of unsupervised methods: prototype-based and pairwise distance-based. The two examples are self-organizing maps and multidimensional scaling (Sammon's mapping). 相似文献
25.
26.
27.
28.
29.
Announcement
Research fellowship in behavioral AIDS research 相似文献30.
Claire M. Payne Raymond B. Nagle Samuel H. Paplanus Anna R. Graham Martin M. Berman 《Ultrastructural pathology》1986,10(6):539-552
Immunohistochemical and ultrastructural findings in two cases of fibrolamellar carcinoma of the liver and two cases of hepatocellular carcinoma of the common histologic type are described. Ultrastructural examination of both cases of fibrolamellar carcinoma revealed the presence of neurosecretory (NS) granules which were sparse in some cells and abundant in others. Many of the tumor cells had a distinct oncocytic appearance with abundant mitochondria. A portion of the glutaraldehyde-fixed neoplasm was processed for the uranaffin reaction (an ultrastructural cytochemical stain specific for the NS granules of neuroendocrine tissue). Abundant uranaffin-positive granules were found in the neoplastic cells of both cases of fibrolamellar carcinoma, whereas no uranaffin-positive granules were found in hepatocellular carcinoma of the common histologic type. There was no statistical difference in the mean diameter of the uranaffin-positive granules measured from both cases. Immunohisto-chemistry revealed the presence of neuron-specific enolase (NSE) and serotonin in one of the two cases of fibrolamellar carcinoma and no NSE staining in two cases of hepatocellular carcinoma of the common histologic type. These findings suggest that some liver tumors presenting histologically as fibrolamellar carcinoma may be neuroendocrine in nature. 相似文献