全文获取类型
收费全文 | 971篇 |
免费 | 78篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 40篇 |
妇产科学 | 5篇 |
基础医学 | 137篇 |
口腔科学 | 44篇 |
临床医学 | 83篇 |
内科学 | 237篇 |
皮肤病学 | 42篇 |
神经病学 | 31篇 |
特种医学 | 151篇 |
外国民族医学 | 1篇 |
外科学 | 79篇 |
综合类 | 39篇 |
预防医学 | 60篇 |
眼科学 | 9篇 |
药学 | 59篇 |
中国医学 | 1篇 |
肿瘤学 | 35篇 |
出版年
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 9篇 |
2018年 | 15篇 |
2017年 | 14篇 |
2016年 | 14篇 |
2015年 | 27篇 |
2014年 | 16篇 |
2013年 | 35篇 |
2012年 | 28篇 |
2011年 | 36篇 |
2010年 | 34篇 |
2009年 | 50篇 |
2008年 | 37篇 |
2007年 | 27篇 |
2006年 | 19篇 |
2005年 | 18篇 |
2004年 | 39篇 |
2003年 | 26篇 |
2002年 | 17篇 |
2001年 | 9篇 |
2000年 | 11篇 |
1999年 | 25篇 |
1998年 | 58篇 |
1997年 | 64篇 |
1996年 | 56篇 |
1995年 | 43篇 |
1994年 | 40篇 |
1993年 | 38篇 |
1992年 | 9篇 |
1991年 | 16篇 |
1990年 | 19篇 |
1989年 | 16篇 |
1988年 | 24篇 |
1987年 | 26篇 |
1986年 | 24篇 |
1985年 | 15篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 21篇 |
1981年 | 3篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1968年 | 3篇 |
1966年 | 3篇 |
1959年 | 2篇 |
排序方式: 共有1058条查询结果,搜索用时 15 毫秒
51.
CJT De Amorim e Silva A Mackenzie LM Hallowell SE Stewart MR Ditchfield 《Journal of Medical Imaging and Radiation Oncology》2006,50(4):319-323
The aim of this study was to evaluate the effectiveness of a practice magnetic resonance unit, in preparing children to undergo magnetic resonance procedures without general anaesthesia (GA) or sedation. The records of children who attended the practice MRI between February 2002 and April 2004 were retrospectively reviewed. Each record was assessed as to whether the child had passed or failed the practice MRI intervention. Those children who were considered to have passed and were proceeded to a clinical non‐GA MRI had the report of the clinical scan reviewed. If the scan had been reported as non‐diagnostic because of movement artefact it was classified as a failed scan, otherwise it was considered a pass. One hundred and thirty‐four children undertook a practice MRI (age range 4.1–16.1 years, median age 7.7 years, 47% boys) and 120/134 (90%) passed the practice session. In all, 117/120 (98%) subsequently had a clinical non‐GA MRI and 110/117 (94%) passed (median age 7.8 years, 47% boys). Preparation is a safe and effective method to reduce the need for sedation and GA in children undergoing a clinical MRI scan. It provides a positive medical experience for children, parents and staff, and results in cost savings for the hospital. 相似文献
52.
53.
L Armenio G Baldini M Bardare A Boner R Burgio G Cavagni M La Rosa F Marcucci M Miraglia del Giudice MR Pulejo 《Archives of disease in childhood》1993,68(2):193-197
After a two week baseline, 209 asthmatic children (mean age 10 years, range 6-17) were randomly allocated to receive 4 mg nedocromil sodium (n = 110) or placebo (n = 99) four times daily for 12 weeks in addition to their current treatment. The children completed daily diary cards and visited the clinic at four week intervals. Statistically significant differences in favour of nedocromil sodium were seen for clinician assessment of asthma severity and diary card symptom scores, pulmonary function and inhaled beta 2 bronchodilator use. Total symptom score decreased by 50% from baseline in the nedocromil sodium group and by 9% in the placebo group during the final four weeks. Nedocromil sodium was considered very or moderately effective by 78% of children/parents (placebo 59%) and 73% of clinicians (placebo 50%). Nausea, headache and sleepiness, and dyspnoea led to withdrawal of one child from nedocromil sodium and placebo treatments, respectively. Reports of sore throat and headache were marginally greater with the nedocromil sodium treatment. It is concluded that nedocromil sodium was both effective and safe in the treatment of asthma in children. 相似文献
54.
MR Sury 《Archives of disease in childhood》1994,71(5):481; author reply 481-481; author reply 482
55.
Guideri F Capecchi PL Lazzerini PE Pasini FL 《Clinical and experimental pharmacology & physiology》2000,27(9):676-679
1. It has been observed that dipyridamole (DIP) administration produces equivalent cardiovascular effects at lower systemic adenosine (ADO) plasma concentrations than those obtained with exogenous ADO infusion. This observation led to the identification of DIP for additional 'ischaemia-inducing' mechanisms, possibly based on sympathetic activation. 2. In turn, exogenous ADO administration has proven to elicit a complex neurohumoral response, including an increase in the plasma concentration of catecholamines, associated with augmented levels of the vasoactive peptides calcitonin gene-related peptide (CGRP) and atrial natriuretic peptide (ANP). More particularly, increases in CGRP seem to be dependent on sympathetic activation, while changes in ANP do not. 3. In order to clarify some aspects of the activity of DIP on neurohumoral systems, the effects of administration of DIP and ADO on plasma levels of noradrenaline (NA), CGRP and ANP were studied in healthy volunteers. Haemodynamic parameters were also monitored. 4. Infusion of exogenous ADO produced plasma levels of ADO as high as 1893+/-386 nmol/L, together with a significant increase in plasma levels of CGRP, ANP and NA. Similarly, the infusion of DIP produced augmented plasma concentrations of the examined parameters, with a peak plasma ADO concentration of 470+/-49 nmol/L. 5. At a given ADO plasma concentration of 450+/-10 nmol/L, the increase in CGRP and NA levels with DIP infusion was significantly higher than that observed following the infusion of ADO, whereas the increase in the plasma concentration of ANP following DIP infusion was very similar to that seen following ADO infusion. 6. The physiological background of these findings is based on evidence that DIP displays a greater sympathoexcitatory activity than does exogenous ADO and only the increase in plasma CGRP seems to be mediated, although indirectly, by beta-adrenoceptor stimulation. The exact mechanism of DIP-dependent sympathetic activation remains to be elucidated. 相似文献
56.
尼群的平对麻醉犬冠脉流量、心肌耗氧量、二氧化碳产生率的影响 总被引:1,自引:0,他引:1
尼群的平20μg/kg iv显著降低麻醉犬血压的过程,冠状窦流量明显增加。持续3h,冠状窦氧含量增加,氧摄取率、心肌耗氧量、二氧化碳产生率降低,持续了3h以上,说明该剂适用于高血压伴心肌缺血。 相似文献
57.
58.
Sickle cell disease: imaging of cerebrovascular complications 总被引:3,自引:0,他引:3
59.
Altered Enzymes in Drug-Resistant Variants of Mammalian Tissue Culture Cells 总被引:25,自引:15,他引:10 下载免费PDF全文
J. D. Sharp N. E. Capecchi M. R. Capecchi 《Proceedings of the National Academy of Sciences of the United States of America》1973,70(11):3145-3149
Two selective procedures are compared in an effort to isolate variants of mouse L cells containing structural gene mutations. Among the resulting variant cloned cell lines are found two types of alterations in the enzyme hypoxanthine phosphoribosyl transferase (EC 2.4.2.8) (1): enzyme with altered kinetic constants causing in vivo and in vitro resistance to 8-azaguanine; and (2) enzyme with altered heat sensitivity in vitro. These results support the view that tissue culture cell variants can arise from structural gene mutations. 相似文献
60.
The effect of barium on blood in the gastrointestinal tract 总被引:2,自引:0,他引:2