全文获取类型
收费全文 | 578篇 |
免费 | 53篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 12篇 |
妇产科学 | 20篇 |
基础医学 | 96篇 |
口腔科学 | 24篇 |
临床医学 | 55篇 |
内科学 | 85篇 |
皮肤病学 | 6篇 |
神经病学 | 32篇 |
特种医学 | 62篇 |
外科学 | 32篇 |
综合类 | 14篇 |
预防医学 | 72篇 |
眼科学 | 4篇 |
药学 | 9篇 |
肿瘤学 | 103篇 |
出版年
2023年 | 4篇 |
2021年 | 12篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 14篇 |
2017年 | 8篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 6篇 |
2013年 | 21篇 |
2012年 | 23篇 |
2011年 | 31篇 |
2010年 | 9篇 |
2009年 | 13篇 |
2008年 | 13篇 |
2007年 | 22篇 |
2006年 | 22篇 |
2005年 | 24篇 |
2004年 | 17篇 |
2003年 | 23篇 |
2002年 | 31篇 |
2001年 | 10篇 |
2000年 | 16篇 |
1999年 | 14篇 |
1998年 | 11篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1993年 | 4篇 |
1992年 | 20篇 |
1991年 | 10篇 |
1990年 | 12篇 |
1989年 | 13篇 |
1988年 | 17篇 |
1987年 | 12篇 |
1986年 | 17篇 |
1985年 | 7篇 |
1983年 | 6篇 |
1982年 | 12篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1977年 | 10篇 |
1975年 | 9篇 |
1974年 | 11篇 |
1971年 | 7篇 |
1970年 | 5篇 |
1967年 | 5篇 |
1966年 | 6篇 |
排序方式: 共有631条查询结果,搜索用时 359 毫秒
81.
82.
B Maciejewski H R Withers J M Taylor A Hliniak 《International journal of radiation oncology, biology, physics》1989,16(3):831-843
In a retrospective study, local control of the primary tumor in 498 squamous cell carcinomas of the oral cavity and oropharynx was analyzed with respect to initial tumor volume, total dose after normalization for variations in fraction size, and to overall treatment time. Primary tumors were grouped into 4 sites, tongue (175), oral cavity including floor of mouth, faucial pillar, soft and hard palate and gingiva (210), tonsil (72) and buccal mucosa (41). Total doses of 60Co irradiation ranged from 30 Gy to 72 Gy, overall treatment times from 15 to 80 days and dose per fraction from 1.8 to 6 Gy. The large number of patients and diversity of dose fractionation patterns permitted assessment of the independent contributions to treatment outcome of stage, fraction size and overall treatment duration. The following conclusions were drawn: (1) Overall treatment time influenced strongly the probability of local tumor control. Over the interval of about 30-55 days used in treating most of this series of patients, an increase of 60 cGy per day, on average, was required for a constant control rate. (2) The increase in dose was attributed to accelerated tumor clonogen growth rate. Such accelerated growth could be a major determinant of failure in protracted regimens. (3) The accelerated rate of regrowth was similar for all tumor sites and stages. (4) The dose for tumor control was relatively independent of variations in fraction size within a range of about 1.6 Gy to 3 Gy: the alpha/beta value in the linear quadratic isoeffect equation was at least 15 Gy. (5) Local control at the primary site required an average of about 3 Gy more for each increase in T stage. This increase most likely reflected an increased number of tumor clonogens, not a decreased tumor cell radiosensitivity. (6) The probability of control at the primary site was less likely if lymph nodes were positive, but this association was only shown to be statistically significant for primaries classified here as oral cavity and oropharynx, not tonsil, tongue or buccal mucosa. (7) After allowing for differences in treatment parameters, especially for heterogeneity in overall treatment times, tumor control probability increased steeply with increase in total dose. (8) A general principle of radiotherapy, at least for squamous carcinomas of head and neck, should be to deliver the desired fractionated dose regimen without unnecessary interruptions and in the shortest time compatible with no reduction in dose below that tolerated by the late-responding normal tissues. 相似文献
83.
84.
85.
Intravascular tumors: transvenous biopsy 总被引:1,自引:0,他引:1
A technique is described for transfemoral biopsy of intravenous tumors. Positive results were obtained at biopsy in three patients who had an intraluminal mass in the inferior vena cava and in one patient with a mass in the iliac vein. Transvenous biopsy is helpful in obtaining a histologic diagnosis and provides an alternative method to surgery or percutaneous transabdominal needle biopsy. 相似文献
86.
J W Pettegrew J Moossy G Withers D McKeag K Panchalingam 《Journal of neuropathology and experimental neurology》1988,47(3):235-248
The histopathological hallmarks of Alzheimer's disease have long been considered to be neurofibrillary tangles (NFT) and neuritic (senile) plaques (SP). Neither of these structures, however, are unique to Alzheimer's disease, and both probably represent end-stage markers of the disorder. NFT have been demonstrated in many disorders; SP occur in small numbers with normal aging. Evidence is presented for elevation of phosphomonoesters (PME) in Alzheimer's brain compared to non-Alzheimer's diseased controls and normal controls. The PME detected by 31P nuclear magnetic resonance (NMR) spectroscopy of autopsy brain are predominantly anabolic precursors of membrane phospholipids. Elevated PME could be secondary to a metabolic block at the rate-limiting enzyme in membrane phospholipid synthesis, which is cytidine triphosphate (CTP): phosphocholine (or phosphoethanolamine) cytidyltransferase (EC 2.7.7.15). Elevated PME could also be secondary to decreased breakdown of PME by phospholipase D activity. Since CTP: phosphocholine cytidyltransferase is inactivated by phosphorylation and since there is independent evidence for hyperphosphorylation of tau and MAP-2 proteins in AD brain, enhanced protein kinase activity could be a common factor. Preliminary evidence suggests that PME could interact with N-methyl-D-aspartate receptors and potentially act as false neurotransmitters. Further studies will be needed to investigate these possibilities. 相似文献
87.
88.
89.
90.