全文获取类型
收费全文 | 337952篇 |
免费 | 10949篇 |
国内免费 | 745篇 |
专业分类
耳鼻咽喉 | 5132篇 |
儿科学 | 11859篇 |
妇产科学 | 9069篇 |
基础医学 | 44367篇 |
口腔科学 | 11768篇 |
临床医学 | 23988篇 |
内科学 | 69551篇 |
皮肤病学 | 9071篇 |
神经病学 | 23499篇 |
特种医学 | 13947篇 |
外国民族医学 | 99篇 |
外科学 | 47126篇 |
综合类 | 1859篇 |
一般理论 | 43篇 |
预防医学 | 30033篇 |
眼科学 | 7630篇 |
药学 | 23422篇 |
2篇 | |
中国医学 | 940篇 |
肿瘤学 | 16241篇 |
出版年
2022年 | 1212篇 |
2021年 | 3798篇 |
2020年 | 2023篇 |
2019年 | 3853篇 |
2018年 | 9290篇 |
2017年 | 7217篇 |
2016年 | 6293篇 |
2015年 | 7949篇 |
2014年 | 8207篇 |
2013年 | 9484篇 |
2012年 | 20030篇 |
2011年 | 16217篇 |
2010年 | 7995篇 |
2009年 | 7853篇 |
2008年 | 11107篇 |
2007年 | 12213篇 |
2006年 | 11714篇 |
2005年 | 19508篇 |
2004年 | 20062篇 |
2003年 | 15132篇 |
2002年 | 10035篇 |
2001年 | 8457篇 |
2000年 | 6602篇 |
1999年 | 9266篇 |
1998年 | 1165篇 |
1992年 | 8016篇 |
1991年 | 8063篇 |
1990年 | 8227篇 |
1989年 | 7641篇 |
1988年 | 7100篇 |
1987年 | 6814篇 |
1986年 | 6523篇 |
1985年 | 5741篇 |
1984年 | 3954篇 |
1983年 | 3210篇 |
1979年 | 4160篇 |
1978年 | 2557篇 |
1977年 | 1981篇 |
1976年 | 1757篇 |
1975年 | 2728篇 |
1974年 | 3404篇 |
1973年 | 3080篇 |
1972年 | 3035篇 |
1971年 | 3053篇 |
1970年 | 2828篇 |
1969年 | 2736篇 |
1968年 | 2487篇 |
1967年 | 2394篇 |
1966年 | 2083篇 |
1965年 | 1264篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
C U Henriques P Damm A Tabor H Goldstein L M?lsted-Pedersen 《Acta obstetricia et gynecologica Scandinavica》1991,70(4-5):295-297
In order to screen for fetal neural tube defects and chromosome abnormalities, amniocentesis was carried out in 334 women with insulin-dependent diabetes mellitus (IDDM) between 1979 and 1987. Two cases (0.6%; 95% confidence limits 0.1-2.2%) of fetal chromosome abnormality were found: one case of Klinefelter's syndrome and one case of de novo translocation. This is comparable to the overall incidence of chromosome abnormality found at birth and is also comparable to the incidence of fetal chromosome abnormality (1.0%) found by amniocentesis at our Department in a group of 2,264 young non-diabetic women with little risk of contracting genetic disorders. The results suggest that maternal IDDM does not increase the risk of fetal chromosome abnormality and consequently screening by amniocentesis for chromosome abnormalities among diabetic women does not seem to be indicated. 相似文献
992.
Herpes simplex virus type 1 infection induces upregulation of interleukin-23 (p19) mRNA expression in trigeminal ganglia of BALB/c mice. 总被引:2,自引:0,他引:2
Eeva K Broberg Niko Set?l? Juha-Pekka Er?linna Aimo A Salmi Matias R?ytt? Veijo Hukkanen 《Journal of interferon & cytokine research》2002,22(6):641-651
We investigated the expression kinetics of several cytokines in trigeminal ganglia (TG) and in brains of BALB/c mice during the course of ocular herpes simplex virus type 1 (HSV-1) infection. All mice recovered from the infection within 2 weeks. The quantitative rapid real-time RT-PCR method was used to analyze interleukin-4 (IL-4), interferon-gamma (IFN-gamma), IL-12p35, IL-12p40, and the recently described IL-23 (p19) mRNA in TG, brain, and splenocyte samples. In TG, we found elevated expression of mRNA for IL-23 (p19) from early acute infection (day 3) to the beginning of the latent phase (day 14). The increase was not detected in brain or in the spleen. IL-4 expression occurred in both TG and brain from the beginning of the experiment to the latent phase. During the latent phase (days 14 and 31), IL-4 expression was significantly elevated in the brain when compared with the uninfected controls (p < 0.05). Considerable expression of IFN-gamma mRNA was detected in TG of mice during acute HSV-1 infection. The expression of IL-23 was detected also in the brains of the mice, even though no significant changes were found during the acute HSV-1 infection. This is, to our knowledge, the first report to show elevated expression of IL-23 (p19) mRNA (p < 0.05) during viral infection in TG of mice. 相似文献
993.
Peptides may function as neurotransmitters liberated antidromically by sensory nerve fibres, provoking vascular responses having potential importance in some neurological disorders. Dose-response relaxation curves induced by substance P (SP) and calcitonin gene related peptide (CGRP) have been studied in porcine ophthalmic arteries in vitro. Both peptides induced vasodilation when tested separately (CGRP much greater than SP). Because of the putative interactions between such peptides in this vascular territory, a computerised system was also used for analysing over time the response to a single addition of either 10(-8) M CGRP, 10(-8) M SP or a combination of 10(-8) M SP + 10(-8) M CGRP. SP did not augment the maximum relaxation induced by CGRP alone, but increased significantly the rate of relaxation during the initial phase of the response. The effect induced by the SP+CGRP combination was stronger than the sum of the individual SP and CGRP-induced relaxations during the first 4 min of the response, which suggests a SP-CGRP synergism in this artery. 相似文献
994.
995.
F St?hlberg A Ericsson B Nordell C Thomsen O Henriksen B R Persson 《Acta radiologica (Stockholm, Sweden : 1987)》1992,33(3):179-200
The present work is intended as a nonmathematical review of the role of flow and motion in nuclear magnetic resonance (MR) imaging. A historical review of MR flow measurement techniques is given, followed by a short overview of flow models in vitro and in vivo. The theory behind the influence of motion on the modulus and phase MR signal information is discussed and effects such as washin/washout, flow-induced signal void, phase offset, and phase dispersion are defined. A simple approach to the concept of MR angiography is given, and methods for quantitative flow measurements such as the phase mapping technique, are surveyed. Aspects of the measurement of diffusion and microcirculation are given, and finally, an overview of the role of MR flow imaging in present and future clinical application is given. 相似文献
996.
R Pereiro García F Alava Moreno M E Díaz García A Sanz-Medel R Narayanaswamy 《Clinica chimica acta; international journal of clinical chemistry》1992,207(1-2):31-40
A fibre optic potassium ion sensor has been developed based on reflectance measurements of the pH-dependent chromogenic crown ether 'Takagi reagent' immobilized on the non-ionic polymeric resin Amberlite XAD2. The sensor response is in the 1.5-100 mM range with a detection limit of 0.25 mM K+. The selectivity factor over sodium is 20. The proposed sensor works with a reproducibility of +/- 0.8% at the 5 mM K+ level. Advantageous design features include ease of construction, simplicity of use, reversibility, short response time (approximately 1 min) and an optimum working pH range (7.0-8.0) for biological fluids. This optical sensor was applied successfully to the direct determination of potassium in human serum. Aqueous potassium standards containing 0.13 M NaCl and a buffer of pH 8 were used for calibration. 相似文献
997.
S S Pedersen H M?ller F Espersen C H S?rensen T Jensen N H?iby 《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》1992,100(4):326-334
Patients with cystic fibrosis commonly acquire chronic pulmonary infection with alginate-producing Pseudomonas aeruginosa. The infection remains localized at the mucosal surfaces of the airways. Using enzyme-linked immunosorbent assays immunoglobulin concentrations and titers of specific antibodies to purified P. aeruginosa alginate and to P. aeruginosa sonicated antigens were measured in tears, saliva, sputum and serum. CF patients had significantly higher concentrations of IgG, IgA and SIgA in serum and saliva than controls. They also had significantly higher levels of specific antibodies to alginate and sonicated antigen in secretions and serum. Local production of IgA, IgG and IgM antibodies to P. aeruginosa was demonstrated. Only a minor proportion of specific IgA antibodies were present as secretory IgA in tears, saliva and sputum. The ratio of alginate-specific SIgA to specific monomeric IgA in sputum was significantly lower than the similar ratio in saliva, whereas the same ratio for specific P. aeruginosa sonicate antigens was found in saliva and sputum. 相似文献
998.
999.
Alex Iranzo Esteban Mu?oz Joan Santamaria Isabel Vilaseca Montserrat Milà Eduardo Tolosa 《Movement disorders》2003,18(10):1179-1183
We evaluated the occurrence of REM sleep behaviour disorder (RBD) and vocal cord abductor paralysis (VCAP) in a group of 9 Machado-Joseph disease (MJD) patients. RBD was diagnosed by clinical history plus audiovisual polysomnography in 4 men and 1 woman (55%). While dreaming, 4 fell out of the bed and the other injured his arms. Laryngoscopy detected bilateral VCAP in 1 patient with stridor who required emergency tracheotomy, and partial vocal cord abductor restriction in 2. RBD and VCAP are two potentially injurious conditions that should be considered part of the clinical spectrum of MJD. 相似文献
1000.
The Troms? study: physical fitness, self reported physical activity, and their relationship to other coronary risk factors.
下载免费PDF全文
![点击此处可从《Journal of epidemiology and community health》网站下载免费的PDF全文](/ch/ext_images/free.gif)
STUDY OBJECTIVE--The aim was to investigate the associations between physical fitness, leisure physical activity, and coronary risk factors. DESIGN--This was a cross sectional study of a random sample of men and women, following a population survey. SETTING--The municipality of Troms?, Norway in 1986-1987. PARTICIPANTS--All men born 1925-1966 and all women born 1930-1966 were invited to the survey; 21,826 subjects attended (81% of the eligible population): of these, 297 men and 312 women, randomly selected, attended the present study (attendance rates 94% in men and 89% in women). MEASUREMENTS AND MAIN RESULTS--Fitness was tested by bicycle ergometry. Physical activity was reported on a questionnaire. Multiple regression analysis was performed with fitness and leisure activity as dependent variables, and coronary risk factors as independent variables. Fitness and leisure activity were positively related (p less than 0.05). Prominent findings for fitness were negative associations with age and smoking (p less than 0.05), and positive associations with body mass index in both sexes (p less than 0.01). HDL cholesterol and systolic blood pressure were significant predictors of fitness in men (p less than 0.01). Smoking emerged as a strong negative predictor for leisure activity in women (p less than 0.01), and a negative relation between leisure activity and total cholesterol was found in men (p less than 0.01). CONCLUSIONS--The study indicates that coronary risk factors are more closely linked to physical fitness than to leisure physical activity. 相似文献