全文获取类型
收费全文 | 1481篇 |
免费 | 48篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 30篇 |
儿科学 | 52篇 |
妇产科学 | 21篇 |
基础医学 | 159篇 |
口腔科学 | 18篇 |
临床医学 | 97篇 |
内科学 | 275篇 |
皮肤病学 | 19篇 |
神经病学 | 41篇 |
特种医学 | 530篇 |
外科学 | 106篇 |
综合类 | 22篇 |
预防医学 | 31篇 |
眼科学 | 2篇 |
药学 | 34篇 |
1篇 | |
中国医学 | 9篇 |
肿瘤学 | 96篇 |
出版年
2022年 | 7篇 |
2021年 | 13篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 22篇 |
2017年 | 20篇 |
2016年 | 27篇 |
2015年 | 26篇 |
2014年 | 36篇 |
2013年 | 42篇 |
2012年 | 49篇 |
2011年 | 58篇 |
2010年 | 49篇 |
2009年 | 50篇 |
2008年 | 59篇 |
2007年 | 68篇 |
2006年 | 61篇 |
2005年 | 54篇 |
2004年 | 51篇 |
2003年 | 58篇 |
2002年 | 42篇 |
2001年 | 41篇 |
2000年 | 28篇 |
1999年 | 39篇 |
1998年 | 41篇 |
1997年 | 38篇 |
1996年 | 55篇 |
1995年 | 47篇 |
1994年 | 44篇 |
1993年 | 26篇 |
1992年 | 28篇 |
1991年 | 32篇 |
1990年 | 24篇 |
1989年 | 35篇 |
1988年 | 36篇 |
1987年 | 22篇 |
1986年 | 22篇 |
1985年 | 23篇 |
1984年 | 19篇 |
1983年 | 16篇 |
1982年 | 13篇 |
1981年 | 9篇 |
1980年 | 18篇 |
1979年 | 11篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 4篇 |
排序方式: 共有1543条查询结果,搜索用时 15 毫秒
91.
92.
Summary
In order to evaluate patients' exposure to radiation in computed tomography, dose quantities such as the computed tomography
dose index (CTDI), multiple scan average dose (MSAD) and dose free in air on the axis of rotation are used. The CTDI and the
MSAD, derivable from the CTDI, are a good measure for the absorbed doses in the examined volume, but they do not take the
biological sensitivity of the organs into account and do not describe the radiogenic risk that is actually relevant for patients
and doctors. The dose on the axis of rotation is not an accurate measure of the effective dose and the radiogenic risk. The
declaration of a limit for the dose on the axis of rotation should take the different regions into account, in order to guarantee
acceptable image quality on one hand and to avoid an unnecessarily high risk on the other side. As physical dose quantities,
the CTDI, MSAD and dose on the axis of rotation are useful to characterize and differentiate between programs and systems
concerning radiation exposure.
Eingegangen am 16. Dezember 1996 Nach überarbeitung angenommen am 14. M?rz 1997 相似文献
93.
94.
The effects of antioxidant supplementation during Percoll preparation on human sperm DNA integrity 总被引:20,自引:6,他引:20
Hughes CM; Lewis SE; McKelvey-Martin VJ; Thompson W 《Human reproduction (Oxford, England)》1998,13(5):1240-1247
The integrity of sperm DNA is crucial for the maintenance of genetic
health. A major source of damage is reactive oxygen species (ROS)
generation; therefore, antioxidants may afford protection to sperm DNA. The
objectives of the study were, first, to measure the effects of antioxidant
supplementation in vitro on endogenous DNA damage in spermatozoa using the
single cell gel electrophoresis (comet) assay and, second, to assess the
effect of antioxidant supplementation given prior to X-ray irradiation on
induced DNA damage. Spermatozoa from 150 patients were prepared by Percoll
centrifugation in the presence of ascorbic acid (300, 600 microM), alpha
tocopherol (30, 60 microM), urate (200, 400 microM), or acetyl cysteine (5,
10 microM). DNA damage was induced by 30 Gy X-irradiation. DNA strand
breakage was measured using the comet assay. Sperm DNA was protected from
DNA damage by ascorbic acid (600 microM), alpha tocopherol (30 and 60
microM) and urate (400 microM). These antioxidants provided protection from
subsequent DNA damage by X-ray irradiation. In contrast, acetyl cysteine or
ascorbate and alpha tocopherol together induced further DNA damage.
Supplementation in vitro with the antioxidants ascorbate, urate and alpha
tocopherol separately has beneficial effects for sperm DNA integrity.
相似文献
95.
标 题 应用ATⅡ受体拮抗剂抗高血压治疗作 者 KjeldsenSE,OmvikP. 参考文献 TidsskrNorLaegeforen,1996,116:504~507研究疾病 高血压病。目 的 评估氯沙坦对心血管死亡率及非致死性心肌梗死和非脑卒中发生率的影响,同时评估该药对充血性心力衰竭或心绞痛所致的总死亡率和住院率的影响,以及长期应用氯沙坦对发生新诊断糖尿病的影响。设 计 随机、三盲、对照研究。病人资料 8300例年龄55~80岁、收缩压在160~200mmHg、舒张压在95~115mmHg的高血压患者,ECG上有左室… 相似文献
96.
Ketai LH; Williamson MR; Telepak RJ; Levy H; Koster FT; Nolte KB; Allen SE 《Radiology》1994,191(3):665
97.
98.
A total of 140 sets of abdominal radiographs were reviewed independently by four qualified diagnostic radiologists. The degree of interobserver agreement was determined by calculating kappa values for 19 commonly used radiographic signs and diagnoses. There was fair to excellent interobserver agreement for 11 signs and diagnoses and poor agreement for the remaining eight. The signs and diagnoses for which agreement is poor cannot be considered reliable and include particularly large bowel obstruction and nonspecific gas pattern. 相似文献
99.
100.
Twenty-eight patients with tumours of the larynx, divided into supraglottic, glottic, and subglottic lesions, and of the hypopharynx were examined by different MRI techniques using the paramagnetic contrast medium Gd-DTPA. The results of preoperative MRI were compared with clinical laryngoscopy and the pathological tumour classification. The examinations were carried out using plain T1-wand T2-weighted and Gd-DTPA enhanced T1-weighted sequences. Most studies included three slice orientations for optimal assessment of different tumour locations. The most accurate diagnostic information was given by Gd-DTPA-enhanced sequences. The combination of plain images, contrast-enhanced images and subtraction enabled precise assessment of deep infiltration. T2-weighted and proton density sequences conveyed more information about cartilage invasion and liquid-filled structures, but gave more artefacts than T1-weighted images. Laryngoscopy had advantages in T1-classified tumors, as the extent of the tumor could be seen, and offered histological information via biopsy. Diagnostic findings of MRI correlated in 85.7% with the pathologist's report, and laryngoscopy provided exact classification in only 64.3% of patients. Gd-DTPA-enhanced MRI is an important adjunct to non-contrast MR studies, and forms an ideal diagnostic supplement to laryngoscopy.
Offprint requests to: T. Vogl 相似文献