全文获取类型
收费全文 | 1113篇 |
免费 | 119篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 19篇 |
儿科学 | 68篇 |
妇产科学 | 23篇 |
基础医学 | 155篇 |
口腔科学 | 39篇 |
临床医学 | 98篇 |
内科学 | 196篇 |
皮肤病学 | 25篇 |
神经病学 | 55篇 |
特种医学 | 283篇 |
外科学 | 61篇 |
综合类 | 45篇 |
预防医学 | 81篇 |
眼科学 | 30篇 |
药学 | 24篇 |
肿瘤学 | 38篇 |
出版年
2021年 | 12篇 |
2020年 | 10篇 |
2019年 | 16篇 |
2018年 | 23篇 |
2017年 | 9篇 |
2016年 | 28篇 |
2015年 | 27篇 |
2014年 | 38篇 |
2013年 | 62篇 |
2012年 | 30篇 |
2011年 | 34篇 |
2010年 | 48篇 |
2009年 | 49篇 |
2008年 | 33篇 |
2007年 | 33篇 |
2006年 | 19篇 |
2005年 | 31篇 |
2004年 | 14篇 |
2003年 | 20篇 |
2002年 | 20篇 |
2001年 | 13篇 |
2000年 | 17篇 |
1999年 | 15篇 |
1998年 | 42篇 |
1997年 | 51篇 |
1996年 | 51篇 |
1995年 | 44篇 |
1994年 | 36篇 |
1993年 | 34篇 |
1992年 | 26篇 |
1991年 | 17篇 |
1990年 | 17篇 |
1989年 | 38篇 |
1988年 | 35篇 |
1987年 | 34篇 |
1986年 | 34篇 |
1985年 | 23篇 |
1984年 | 14篇 |
1983年 | 17篇 |
1982年 | 8篇 |
1981年 | 15篇 |
1980年 | 10篇 |
1979年 | 13篇 |
1978年 | 11篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1971年 | 5篇 |
1968年 | 9篇 |
1967年 | 5篇 |
排序方式: 共有1240条查询结果,搜索用时 15 毫秒
71.
Substrate utilization and hormonal responses to moderate intensity exercise during pregnancy and after delivery 总被引:3,自引:0,他引:3
Bessinger RC McMurray RG Hackney AC 《American journal of obstetrics and gynecology》2002,186(4):757-764
OBJECTIVE: This study was undertaken to examine substrate utilization and hormonal responses to moderate intensity exercise in the same group of women across gestation. STUDY DESIGN: Glucose, triglyceride, insulin, glucagon, cortisol, growth hormone, and blood urea nitrogen levels were measured in 12 women at rest and after exercise. Heart rate, oxygen uptake, and respiratory exchange ratio were measured at rest and during exercise. Urine urea nitrogen levels, urine volume, and creatinine levels were measured 24 hours before and after exercise. Each woman completed a 30-minute treadmill walk at 65% of her predicted maximal heart rate at the same time of day during the 22nd and 33rd weeks of gestation and at 14 weeks after delivery. RESULTS: There were no significant differences between exercise trials in oxygen uptake, respiratory exchange ratio, or heart rate. Pregnancy elevated resting triglyceride levels but lowered plasma glucose levels. Exercise during pregnancy caused a reduction in plasma glucose levels but elevated circulating triglyceride levels (P <.05). Resting levels of cortisol, growth hormone, and insulin were elevated during pregnancy compared with after delivery, but resting glucagon levels were not affected by pregnancy. Exercise caused circulating levels of cortisol, growth hormone, and glucagon to increase (P <.05). The exercise-induced change in the cortisol level was greater during pregnancy than that after delivery. The exercise-induced changes in growth hormone and glucagon levels were greatest after delivery compared with those during pregnancy (P <.05). Exercise reduced insulin levels (P <.05), with the greatest reduction at 33 weeks' gestation. There were no significant differences in urine urea nitrogen excretion as a result of exercise. CONCLUSIONS: Certain substrate and hormonal responses to exercise are altered as pregnancy progresses. Quantitatively, protein appears to be a relatively unimportant fuel during a 30-minute bout of moderate intensity exercise in this group of women evaluated during pregnancy and after delivery. Furthermore, a 30-minute bout of moderate intensity exercise would not be expected to compromise fetal amino acid availability. 相似文献
72.
OBJECTIVE: To determine the within subject (day to day) variability for variables reflecting iron status (concentrations of ferritin and soluble transferrin receptor (sTfR), and the sTfR/logFerr index) in female athletes during a training camp, and in female control subjects. RESULTS: The error for ferritin concentration was nearly twice as high in athletes as in controls, that for sTfR concentration was identical in the two groups, and that for the sTfR/logFerr index was about 50% higher in athletes than in controls. CONCLUSIONS: The within subject, day to day error for the sTfR/logFerr index computed from data recorded for untrained subjects cannot serve as a reference value for training athletes. When the sTfR/logFerr index is used to monitor iron stores in athletes, an error value of 0.20 should be used, because determination of the index after a few days of rest may not be feasible. 相似文献
73.
Background
Low grade fibromyxoid sarcomas (LGFMS) are very rarely seen. They commonly arise from deep soft tissues of the lower extremities. Very few cases of intra-abdominal location have been reported. 相似文献74.
Mark?RoyEmail author Clemens?Kirschbaum Andrew?Steptoe 《Annals of behavioral medicine》2003,26(3):194-200
Intraindividual variation in recent stress exposure and its impact upon cortisol and testosterone was investigated. Over 1
year, 72 young male firefighters completed the Daily Stress Inventories, for 2 shift cycles (16 days), every 3 months. At
the end of each 16-day period each participant attended a 1-hr morning assessment session. Saliva samples and blood pressure
measurements were taken at 10-min intervals, and at 30 min, a blood sample was drawn. Across the year of assessment, there
were significant linear relationships in reported stress and in neuroendocrine activity. In contrast to expectations, as daily
stress decreased across the year (p < .008), salivary cortisol increased (p < .001) and testosterone levels decreased (p <
.001). Within-subjects comparisons of the sessions with the highest and lowest stress confirmed these linear relationships:
Lower stress prior to the assessment session was associated with higher cortisol levels (p < .01). These results, though in
contrast to the orthodoxy concerning the association between stress and cortisol, are supported by findings in a number of
other studies and may constitute down regulation of cortisol activity following an increment in stress exposure.
This research was supported by the Medical Research Council, United Kingdom. We are grateful to the London Fire & Civil Defence
Authority for their cooperation. 相似文献
75.
NJ Hoogenraad JD Mitchell NA Don TM Sutherland AC Mc Leay 《Archives of disease in childhood》1980,55(4):292-295
The activity of urea cycle enzymes was assayed in duodenal biopsy specimens obtained from a female infant who presented with neonatal hyperammonaemia. All enzyme levels were normal except N-acetyl glutamate-dependent carbamyl phosphate synthetase 1 (CPS1) which was half the mean activity in normal control specimens. A similar deficiency of CPS1 was also shown in duodenal specimens from the patient's mother who became slightly symptomatic after relatively high protein meals and during pregnancy, and had spontaneously modified her diet to one with protein restriction. The patient is growing normally on a dietary regimen similar to that spontaneously adopted by her mother. Urea cycle enzyme activity in the duodenal biopsy material from the controls was similar to that found in the normal human liver and appears to have distinct advantages as a means of assaying for urea cycle defects in patients with hyperammonaemia and their relatives. 相似文献
76.
Scaphoid fractures are among the most common hand fractures in adults. The geometry of the scaphoid as it relates to its retrograde
blood supply renders it particularly prone to avascular necrosis and other fracture complications. Though there has been long-standing
debate over the optimal method of diagnosing scaphoid fractures, the best and most cost-effective methods combine clinical
exam with other imaging modalities such as navicular view plain films, CT, and MRI for particularly questionable presentations.
Once a scaphoid fracture is diagnosed, it should be followed by an orthopaedic surgeon and treated with cast immobilization
or operative management in the case of displaced fractures. Fractures should be followed to monitor healing progress in order
to ensure the eventual development of bridging bone across the fracture line, usually best appreciated on CT. Proper treatment
of scaphoid fractures and assessment of fracture healing can minimize the occurrence of non-unions and associated arthritic
changes. 相似文献
77.
由于治疗方法的进步,近80%的儿童和青少年癌症患者能够长期生存。在美国,约有270000例儿童癌症的幸存者,即每640名20至39岁成年人中就有一名幸存者。大量的幸存者有利于儿童癌症治疗后长期健康结果的研究。现在可以明确的是,化疗和放疗所致的儿童各器官系统损害在临床上可能潜伏多年。为了全面了解治疗儿童癌症而继发的健康问题,重要的是衡量三项长期结果:健康状况、死亡率和患病率。这三项中,关于前两项已有相当好的研究报道。在一项对20227例癌症5年生存者的回顾性分析中,Mertens等发现以下原因导致的超额死亡率具有统计学意义:继发癌症(… 相似文献
78.
79.
80.