全文获取类型
收费全文 | 10530篇 |
免费 | 600篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 252篇 |
儿科学 | 371篇 |
妇产科学 | 146篇 |
基础医学 | 1582篇 |
口腔科学 | 335篇 |
临床医学 | 1038篇 |
内科学 | 1870篇 |
皮肤病学 | 250篇 |
神经病学 | 819篇 |
特种医学 | 531篇 |
外科学 | 1493篇 |
综合类 | 105篇 |
一般理论 | 9篇 |
预防医学 | 610篇 |
眼科学 | 403篇 |
药学 | 736篇 |
中国医学 | 21篇 |
肿瘤学 | 583篇 |
出版年
2022年 | 55篇 |
2021年 | 123篇 |
2020年 | 83篇 |
2019年 | 131篇 |
2018年 | 159篇 |
2017年 | 148篇 |
2016年 | 172篇 |
2015年 | 194篇 |
2014年 | 230篇 |
2013年 | 354篇 |
2012年 | 403篇 |
2011年 | 474篇 |
2010年 | 290篇 |
2009年 | 259篇 |
2008年 | 441篇 |
2007年 | 465篇 |
2006年 | 474篇 |
2005年 | 455篇 |
2004年 | 445篇 |
2003年 | 422篇 |
2002年 | 334篇 |
2001年 | 425篇 |
2000年 | 373篇 |
1999年 | 334篇 |
1998年 | 167篇 |
1997年 | 149篇 |
1996年 | 143篇 |
1995年 | 107篇 |
1994年 | 109篇 |
1993年 | 75篇 |
1992年 | 183篇 |
1991年 | 166篇 |
1990年 | 181篇 |
1989年 | 188篇 |
1988年 | 150篇 |
1987年 | 139篇 |
1986年 | 128篇 |
1985年 | 130篇 |
1984年 | 91篇 |
1983年 | 82篇 |
1982年 | 57篇 |
1980年 | 59篇 |
1979年 | 87篇 |
1978年 | 75篇 |
1977年 | 87篇 |
1975年 | 61篇 |
1974年 | 58篇 |
1973年 | 56篇 |
1972年 | 81篇 |
1938年 | 54篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Anuj Shrestha Zeeshan Jawa Kathryn L. Koch Amy B. Rankin Qun Xiang Anand Padmanabhan Matthew S. Karafin Joshua J. Field 《Journal of clinical apheresis》2015,30(6):353-358
Red cell exchange (RCE) is a common procedure in adults with sickle cell disease (SCD). Implantable dual lumen Vortex (DLV) ports can be used for RCE in patients with poor peripheral venous access. We performed a retrospective cohort study of RCE procedures performed in adults with SCD. The main objective of the study was to compare the inlet speed, duration of procedures and rate of complications performed through DLV ports to those performed through temporary central venous and peripheral catheters. Twenty‐nine adults with SCD underwent a total of 318 RCE procedures. Twenty adults had DLV ports placed and 218 procedures were performed using DLV ports. Mean length of follow‐up after DLV port placement was 397 ± 263 days. Six DLV ports were removed due to infection and 1 for malfunction after a mean of 171 ± 120 days. Compared to temporary central venous and peripheral catheters, DLV port procedures had a greater rate of procedural complications, a longer duration, and a lower inlet speed (all P < 0.01). When accounting for the maximum allowable inlet speed to avoid citrate toxicity, 40% of DLV port procedures were greater than 10% below maximum speed, compared to 7 and 14% of procedures performed through temporary central venous and peripheral catheters (P < 0.0001). In conclusion, DLV ports can be used for RCE in adults with SCD, albeit with more procedural complications and longer duration. The smaller internal diameter and longer catheter of DLV ports compared to temporary central venous catheters likely accounts for the differences noted. J. Clin. Apheresis 30:353–358, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
2.
Maria Ricci Agostino Chiaravalloti Alessandro Martorana Giacomo Koch Vincenzo De lucia Gaetano Barbagallo Orazio Schillaci 《Annals of nuclear medicine》2020,34(4):254-262
The aim of our study was to investigate the impact of the epsilon phenotype in brain glucose consumption in a population with Alzheimer’s disease. Statistical Parametric Mapping (SPM8) was used to investigate differences in brain glucose consumption (as detectable by means of 18F FDG-PET/CT) in the population examined. A total of 129 patients (72 females and 57 males) with a diagnosis of probable AD according to the NINCDS-ADRDA criteria underwent the PET/CT examination. The mean (SD) age of the patients was 70 (± 7) years; the mean Mini-Mental State Examination was 19(± 5.6). 59 expressed epsilon 4 phenotype (E4) and 70 expressed the epsilon 3 phenotype (E3). Cerebral spinal fluid amyloid, tau, and t-tau have been measured resulting equal to 367.4 (± 149.1), 584.7 (± 312.1), and 79.2(± 45.9) pg/ml, respectively. Patients with confirmed amyloid and Tau changes were classified as AD. Patients with amyloid changes but negative Tau, considered as high risk of AD, were classified as IAD. Age, sex, MMSE, scholarship, and CSF parameters were used as a covariate in the SPM analyses. We did not find significant differences in age, gender, and MMSE and CSF parameters among groups. In the analysis of the AD group as compared to AD-E3, AD-E4 subjects show a significant reduction of brain glucose consumption in inferior frontal gyrus bilaterally (BA 45, BA 47). In the analysis of the IAD group as compared to IAD-E3, IAD-E4 subjects show a significant reduction of brain glucose consumption in right in medial, middle, and superior frontal gyrus (BA10, BA11), and in left medial and middle frontal gyrus (BA10, BA11). The differences between IAD-E3 and AD-E3 and between IAD-E4 and AD-E4 (and vice versa analysis) resulted not significant. APO-e4 is related to a major involvement of the frontal cortex confirming its role of risk factor in AD, while APO-3 seems not related to a specific pattern, supporting the hypothesis of neutral/protective role in AD. 相似文献
3.
A Hugoson G Koch T Bergendal A L Hallonsten L Laurell D Lundgren J E Nyman 《Swedish dental journal》1986,10(3):103-117
The aim of the present study was to present data from dental care habits and knowledge of oral health in two cross-sectional studies carried out in 1973 and 1983. A random sample of approximately 1000 individuals evenly distributed in the age groups 3, 5, 10, 15, 20, 30, 40, 50, 60 and 70 years was studied for each of these two years. In the 1983-year examination 80 individuals 80 years of age were also included. All subjects were inhabitants of the community of J?nk?ping, Sweden. A questionnaire about dental care habits and knowledge was used in combination with a clinical and radiographical examination. The participants answered 23-101 questions. The same questions were raised in 1973 and 1983. For most age groups more then 80 per cent visited a dentist yearly in 1983. This yearly attendance was higher than that for 1973. In the 20-year-old group 14 per cent of the individuals received dental care in the PDS in 1973 compared to 63 per cent in 1983. The main reason to visit a dentist in 1973 was by the patient's own initiative while in 1983 the appointments were based on the dentist's initiative. The number of subjects that felt discomfort in connection with a visit to the dentist had decreased between 1973 and 1983. Knowledge about the etiology of caries had increased between 1973 and 1983 was not the case for gingivitis and periodontitis. An increase had occurred in toothbrushing frequency and the use of toothpicks and disclosing tablets but this between 1973 and 1983. In 1983, 98 to 93 per cent of the subjects in the age groups 10-30 years had been exposed to topical fluorides. The corresponding figure for 30-year-olds in 1973 was 1 per cent. It is obvious that during the period 1973 to 1983 there has been an increase in dental attendance, knowledge of dental diseases, oral health and the use of preventive measures. 相似文献
4.
Sylke Andreas Jörg Dirmaier Timo Harfst Stephan Kawski Uwe Koch Holger Schulz 《European psychiatry》2009,24(2):105-111
The aim of this study was to evaluate a case-mix system to classify inpatients with mental disorders in Germany by means of self-report and expert-rated instruments. The use of case-mix systems enhances the transparency of performance and cost structure and can thus improve the quality of mental health care. We analysed a consecutive sample of 1677 inpatients with mental disorders from 11 hospitals using regression tree analysis. The model assigns patients to 17 groups, accounting for 17% of the variance for duration of stay. Patients with eating disorders had a longer duration of stay than patients with anxiety disorder, duration of mental illness of less than 3–5 years, lower levels of interpersonal problems and higher occupational position. The results showed that besides diagnosis, variables such as duration of illness and interpersonal problems are important for classifying inpatients with mental disorders. The results of the study should be critically reviewed regarding the empirical results of other studies and the appropriateness of case group concepts for inpatients with mental disorders. 相似文献
5.
Few cases in the history of epidemiology and public health are more famous than John Snow's investigation of a neighborhood cholera outbreak in the St. James, Westminster, area of London in 1854. In this study Snow is assumed to have proven that cholera was water rather than airborne through a methodology that became, and to a great extent remains, central to the science and social science of disease studies. And yet, Snow's work did not satisfy most of his contemporaries who considered his proof of a solely waterborne cholera interesting but unconvincing. Uniquely, this paper asks whether the caution of Snow's contemporaries was reasonable, and secondly, whether Snow might have been more convincing within the science of the day. The answers significantly alter our understanding of this paradigmatic case. It does so in a manner offering insights both into the origins of nineteenth century disease analysis and more generally, the relation of mapping in the investigation of an outbreak of uncertain origin. The result has general relevance—pedagogically and practically—in epidemiology, medical geography, and public health. 相似文献
6.
7.
Dr. E. Mietzsch M. Koch M. Schaldach J. Werner B. Bellenberg K. U. Wentz 《Medical & biological engineering & computing》1998,36(6):673-678
The application of spin-echo magnetic resonance imaging sequences on non-invasive temperature imaging for temperature mapping
of human limbs is investigated. In an in vitro expriment performed on a meat sample, the equilibrium magnetisation P and the
spin-lattice relaxation time T1 are calculated from the values for the repetition time TR and the signal intensities obtained by a spin-echo sequence at
different tissue temperatures tures as measured by a fibre-optic probe. T1 is linearly correlated to the tissue temperature, and P is linearly correlated to the reciprocal value of the absolute temperature.
Both effects, taken together, lead to a non-linear dependency of the signal intensity on temperature. Therefore a TR leading
to maximum temperature dependency of the signal intensity is calculated and used in the futher experiments. In the in vivo
experiments, the lower legs of two volunteers are cooled from outside. Images are acquired with a spin-echo sequence (1.5T,
TR=1200 ms, TE=10 ms). A rise in signal intensity in the muscle with falling skin temperature is observed, particularly in
more peripheral muscle layers. This study shows that spin-echo sequences can be used to monitor temperature changes and temperature
differences in living muscle tissue. 相似文献
8.
The effect of bone drilling on pain in gonarthrosis 总被引:1,自引:0,他引:1
Summary Seventy-seven patients with mild to moderate gonarthrosis of the knee were treated by subchondral bone drilling, and followed for from 2 to 7 years. Patients with generalised arthrosis benefited more than those with unicompartmental involvement. Pain, assessed by a visual analogue scale, was significantly reduced compared with a control group of 16 patients who had a diagnostic arthroscopy only. Drilling is a safe procedure with few complications and can be used in patients when more extensive surgery is not yet indicated or possible.
Résumé Vingt-sept cas d'arthrose légère ou modérée du genou, diagnostiqués par arthroscopie et traités par forage, ont été revus avec un recul moyen de 4 ans (de 2 à 7 ans). La douleur, évaluée selon la cotation VAS, était diminuée pendant 24 mois en moyenne (1 à 76) dans les deux tiers des cas. Les résultats étaient meilleurs chez les patients présentant une arthrose globale que chez ceux atteints d'une arthrose uni-compartimentale. Ils étaient obtenus aussi bien dans les cas douloureux au repos (n=39) que dans ceux douloureux lors de la mobilisation du genou (n=14). Les complications ont été exceptionnelles (n=1). La douleur était diminuée dans une proportion significativement supérieure dans les genoux traités par forage que dans un groupe de contrôle de 16 cas, n'ayant subi qu'une arthroscopie à visée diagnostique (p=0.006). Le forage est un procédé sûr, n'entraînant que de rares complications. Il est indiqué dans le traitement des douleurs du genou chez les patients ayant une arthrose légère ou modérée, lorsque des interventions plus importantes ne sont ni nécessaires, ni réalisables.相似文献
9.
10.
Purified acetylcholinesterase from bovine brain was reconstituted by a detergent depletion technique into liposomes, prepared from soybean lecithin. The kinetics for the substrate acetylthiocholine and for three inhibitors with very different binding properties was studied. The results were compared with results from corresponding experiments with solubilized enzyme in detergent solution. The reconstituted enzyme showed a higher affinity for acetylthiocholine, ketamine and fasciculin. Parameters unaffected by the reconstitution were: turnover number for the substrate; the non-competitive component in ketamine inhibition and the kinetics for the active site-directed irreversible inhibitor soman. 相似文献