全文获取类型
收费全文 | 33508篇 |
免费 | 2114篇 |
国内免费 | 368篇 |
专业分类
耳鼻咽喉 | 669篇 |
儿科学 | 460篇 |
妇产科学 | 595篇 |
基础医学 | 5408篇 |
口腔科学 | 661篇 |
临床医学 | 2756篇 |
内科学 | 6338篇 |
皮肤病学 | 1357篇 |
神经病学 | 2340篇 |
特种医学 | 2173篇 |
外科学 | 4257篇 |
综合类 | 154篇 |
现状与发展 | 1篇 |
一般理论 | 20篇 |
预防医学 | 1394篇 |
眼科学 | 918篇 |
药学 | 3273篇 |
中国医学 | 447篇 |
肿瘤学 | 2769篇 |
出版年
2023年 | 253篇 |
2022年 | 790篇 |
2021年 | 1246篇 |
2020年 | 648篇 |
2019年 | 897篇 |
2018年 | 1068篇 |
2017年 | 880篇 |
2016年 | 1262篇 |
2015年 | 1741篇 |
2014年 | 2018篇 |
2013年 | 2204篇 |
2012年 | 3261篇 |
2011年 | 3035篇 |
2010年 | 1887篇 |
2009年 | 1475篇 |
2008年 | 1955篇 |
2007年 | 1792篇 |
2006年 | 1671篇 |
2005年 | 1471篇 |
2004年 | 1172篇 |
2003年 | 990篇 |
2002年 | 896篇 |
2001年 | 404篇 |
2000年 | 368篇 |
1999年 | 319篇 |
1998年 | 171篇 |
1997年 | 131篇 |
1996年 | 111篇 |
1995年 | 96篇 |
1994年 | 84篇 |
1993年 | 75篇 |
1992年 | 164篇 |
1991年 | 164篇 |
1990年 | 123篇 |
1989年 | 157篇 |
1988年 | 123篇 |
1987年 | 116篇 |
1986年 | 103篇 |
1985年 | 86篇 |
1984年 | 77篇 |
1983年 | 51篇 |
1982年 | 38篇 |
1981年 | 40篇 |
1980年 | 35篇 |
1979年 | 37篇 |
1978年 | 26篇 |
1975年 | 25篇 |
1974年 | 31篇 |
1973年 | 29篇 |
1972年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
J B Schutte J de Jong E J van Weerden S Tamminga 《The British journal of nutrition》1992,68(1):195-207
The pentose sugar L-arabinose is one of the most abundant components released by complete hydrolysis of non-starch polysaccharides of feed ingredients of vegetable origin. Two studies were conducted to investigate the apparent ileal digestibility and urinary excretion of L-arabinose at dietary inclusion levels of 50 and 100 g/kg, and 25, 50, 75 and 100 g/kg respectively, in pigs. As a reference, D-glucose was included in the studies. Water intake, ileal flow of volatile fatty acids and ileal and faecal digestibilities of dietary nutrients in pigs fed on the different diets were also examined. Castrated pigs were prepared with a post-valvular T-caecum cannula to measure ileal digestibility. Faecal digestibility was measured in non-cannulated pigs. Apparent ileal digestibility of L-arabinose was found to be approximately 70%. The presence of L-arabinose in the diet increased ileal flow of volatile fatty acids and lactic acid, suggesting the occurrence of microbial degradation of L-arabinose in the pig small intestine. L-arabinose was partly excreted in the urine. The extent of this urinary excretion as a percentage of intake increased linearly (P < 0.01) as the dietary level increased. In pigs fed on the 25 g L-arabinose/kg diet, 10.9% of the L-arabinose consumed appeared in the urine. This level was increased to 14.7% when pigs were fed on a diet containing 100 g L-arabinose/kg diet. Faecal digestibility and retention of nitrogen decreased significantly in pigs fed on the L-arabinose diets. 相似文献
43.
Influence of treatment on peak expiratory flow and its relation to airway hyperresponsiveness and symptoms. The Dutch CNSLD Study Group. 总被引:2,自引:1,他引:1 下载免费PDF全文
BACKGROUND--Despite effective treatments, the morbidity and mortality of obstructive airways disease (asthma and COPD) remains high. Home monitoring of peak expiratory flow (PEF) is increasingly being advocated as an aid to better management of obstructive airways disease. The few available studies describing effects of treatment on the level and variation of PEF have involved relatively small numbers of subjects and did not use control groups. METHODS--Patients aged 18-60 years were selected with PC20 < or = 8 mg/ml and FEV1 < 95% confidence interval of predicted normal. They were randomised to receive, in addition to a beta 2 agonist, either an inhaled corticosteroid (BA+CS), an anticholinergic (BA+AC), or a placebo (BA+PL). One hundred and forty one of these subjects with moderately severe obstructive airways disease completed seven periods of two weeks of morning and afternoon PEF measurements at home during 18 months of blind follow up. RESULTS--Improvements in PEF occurred within the first three months of treatment with BA+CS and was subsequently maintained: the mean (SE) increase in morning PEF was 51 (8) l/min in the BA+CS group compared with no change in the other two groups. Similarly, afternoon PEF increased by 22 (7) l/min. Diurnal variation in PEF (amplitude %mean) decreased from 18.0% to 10.2% in the first three months of treatment with BA+CS. Within-subject relations between changes in diurnal variation in PEF and changes in PC20 were found to be predominantly negative (median rho-0.40) but with a large scatter. Relations between diurnal variation in PEF and changes in symptom scores, FEV1, and bronchodilator response were even weaker. CONCLUSIONS--In patients with moderately severe obstructive airways disease, PEF rates and variation are greatly improved by inhaled corticosteroids. Since the relation of diurnal PEF variation with PC20, symptoms, FEV1, and bronchodilator response were all weak, these markers of disease severity may all provide different information on the actual disease state. PEF measurements should be used in addition to the other markers but not instead of them. 相似文献
44.
Ultrasound microbubble induced endothelial cell permeability. 总被引:1,自引:0,他引:1
A van Wamel K Kooiman M Emmer F J ten Cate M Versluis N de Jong 《Journal of controlled release》2006,116(2):e100-e102
45.
46.
Simple measurement of spinal cord evoked potential: a valuable data source in the rat spinal cord injury model. 总被引:1,自引:0,他引:1
Jong-Pil Park Ki-Jeong Kim Ji Hoon Phi Chul-Kee Park Jong-Hoon Kim Hyo Jin Kang Dohun Lee Kyu Hyun Han Kyu-Chang Wang Sun Ha Paek 《Journal of clinical neuroscience》2007,14(11):1099-1105
Measurement of spinal cord evoked potentials (SCEPs) is proposed as a means of predicting locomotion outcome in the rat spinal cord injury (SCI) model. Using 55 rats, three reproducible peak waves (waves I, II and III) were observed during stimulation at the C7 level with recording at the L1 epidural space. Hemisection at the T13 level showed three wave loss patterns: wave III loss only, loss of both wave II and III, and loss of all three waves. Defining an ideal SCI model as establishment of stable monoparesis or paraparesis, all animals in the wave II-III loss group showed favorable results. Histological data and electrophysiological properties allowed reasonable assumptions of wave origin: wave I from extrapyramidal tracts, wave II from the ventral corticospinal tract, and wave III from the dorsal corticospinal tract. Complete destruction of pyramidal tracts in both dorsal and ventral fibers was essential for long-term impairment of locomotion. 相似文献
47.
Jae Sue Choi Han Suk Young Jong Cheol Park Jin-Ho Choi Won Sick Woo 《Archives of pharmacal research》1986,9(4):233-236
The flavonoids isolated from the leaves ofRhododendron brachycarpum, were identified as quercetin, avicularin, quercitrin and hyperin. 相似文献
48.
49.
H. N. P. M. Sondag H. A. A. De Jong J. van Marle B. Willekens W. J. Oosterveld 《Brain research bulletin》1996,40(5-6):353-356
The relation between prolonged hypergravity and structural adaptation of otoconia was studied in hamsters (n = 56). Three groups of hamsters (n = 27), were conceived and born in a centrifuge: group 1 (n = 10) 1 month under 2.5 G, group (2n = 9) 5 months under 2.5 G and 4 months under 1 G, group 3 (n = 8) 1 month under 2.5 G and 8 moths under 1 G. Control hamsters (n = 29) were conceived and born under 1 G (1 month old, n = 7; 9 months old, n = 22). Histological study of the otoconial layers (energy dispersive x-ray element analysis and scanning electron microscopy) showed similar calcium content, size, and shape in utricular and saccular otoconia in all groups. Different were the utricular otoconial size classes, large, medium-sized, a and small. The area with small otoconia increased in group 1 (p = 0.002). In group 2, the large otoconial area decreased (p < 0.001) and the medium-sized one increased (p < 0.001). In group 3, the large otoconial area decreased (p = 0.003) and the medium-sized one increased (p = 0.007). For age-related effects we found group 1 with an increased area of large otoconia (p = 0.001) and a decreased medium-sized one compared to groups 2 (p < 0.001) and 3 (p = 0.02). Hypergravity during formation of otoconia does not affect calcium content, size, or shape, but changes relative size of the areas with large, medium-sized, or small otoconia and the development of these areas. This resulted in a structural adaptation to hypergravity. 相似文献
50.
Randomised trial comparing the upright and supine positions for the second stage of labour 总被引:2,自引:1,他引:1
P. R. de Jong Senior Specialist R. B. Johanson Senior Lecturer P. Baxen Chief Professional Nurse V. D. Adrians Senior Professional Nurse S. van der Westhuisen Lecturer P. W. Jones Professor 《BJOG : an international journal of obstetrics and gynaecology》1997,104(5):567-571
Objective To assess the maternal and neonatal effects of upright compared with recumbent positions during delivery, in terms of defined outcome variables.
Design A randomised controlled trial.
Setting St Monica's Nursing Home, a midwife based maternity unit in Cape Town, South Africa.
Participants Five hundred and seventeen women of low obstetrical risk assigned to deliver at the nursing home.
Results The trial showed that women who adopted the upright posture for delivery experienced less pain, perineal trauma and fewer episiotomies than those who delivered in the supine position.
Conclusion The data suggest that in women of low obstetrical risk, choice of posture during delivery may be encouraged. 相似文献
Design A randomised controlled trial.
Setting St Monica's Nursing Home, a midwife based maternity unit in Cape Town, South Africa.
Participants Five hundred and seventeen women of low obstetrical risk assigned to deliver at the nursing home.
Results The trial showed that women who adopted the upright posture for delivery experienced less pain, perineal trauma and fewer episiotomies than those who delivered in the supine position.
Conclusion The data suggest that in women of low obstetrical risk, choice of posture during delivery may be encouraged. 相似文献