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排序方式: 共有756条查询结果,搜索用时 15 毫秒
1.
Shaping ability of the M4 handpiece and Safety Hedstrom Files in simulated root canals 总被引:1,自引:0,他引:1
A. LLOYD A. JAUNBERZINS A. DHOPATKAR S. BRYANT P. M. H. DUMMER 《International endodontic journal》1997,30(1):16-24
The aim of this study was to assess the shaping ability of the M4 reciprocating handpiece and Safety Hedstrom files in simulated canals. A total of 40 simulated canals of various angles and positions of curvature were prepared with an M4 handpiece using Safety Hedstrom files oriented with the ground, flattened surface towards the inner aspect of the curve. A standard regimen was adopted throughout. Pre- and post-operative longitudinal images of the canals were taken with a video camera and stored and manipulated in a computer with image analysis software. The presence of canal aberrations and the amount and location of resin material removed as a result of preparation were determined from composite images of superimposed pre- and post-operative views. Preparation time varied significantly (P<0.001) between the canal types; overall, 20° canals were prepared more quickly than 40° canals. Zips and elbows were observed in 16 out of the 40 canals with most (11) being created in 40° specimens. Ledges were found in 19 canals and perforations in only 1. There were no significant differences between canal shapes for these aberrations. Excessive removal of material from the inner aspect of the canal at the curve to create a danger zone was found in 20 canals, but only in those with 40° curves. Significant differences in total canal width between the canal types were seen at the zips (P<0.05), elbows (P<0.05) and danger zones (P<0.001). Transportation at the danger zones varied significantly (P<0.001) between canal types. Under the conditions of this study, the M4 handpiece and Safety Hedstrom files created hour-glass preparations in a substantial proportion of canals. In reality, the Safety Hedstrom file with its one flattened surface was ineffective at reducing removal of material along the inner aspect of canal curves in severely curved specimens and clearly has the potential to create strip perforations in teeth. 相似文献
2.
Identifying environmental factors reflected to alcohol use is important for program planning and evaluation in college alcohol and drug prevention programs. Little has been written concerning uses of data in environmental prevention efforts. This paper presents four brief interrelated case studies of how environmental modifications were used by a college alcohol prevention project to 1) change the marketing practices and service policies of a student-oriented bar, 2) alter the sales practices of a campus bookstore concerning alcohol paraphernalia, 3) to develop a campaign with the goal of reducing risk factors related to heavy drinking at private student parties, and 4) stop an unsafe bus from transporting students to bars in Mexico. Creative use of such environmental prevention approaches has potential benefit to colleges and universities concerned with the primary prevention of alcohol-related problems experienced by students. 相似文献
3.
William A. Meier-Ruge Alois F. Schärli Franz Stoss 《Pediatric surgery international》1995,10(7):454-458
In a methodological survey, the technical prerequisites for optimal histopathological diagnosis of gut dysganglionosis are presented. To make a proper diagnosis, the pediatric surgeon or gastroenterologist and the pathologist must consider certain preconditions. The most important steps for the optimal biopsy diagnosis of an aganglionosis, an ultrashort Hirschsprung segment, a intestinal neuronal dysganglionosis (IND), a ganglioneuromatosis, a hypogenesis, or immaturity of the vegetative gut innervation are: (1) taking 3–4 biopsies the size of a peppercorn (3–5 mm3) with submucosa; (2) the best instruments for taking rectal mucosal biopsies are forceps and scissors or a conventional large biopsy forceps; and (3) biopsies may be taken 1 cm, 3–4 cm, 6–9 cm, and 9–12 cm (or from a preternatural anus) above the pectinate line. A biopsy containing mucosa, muscularis mucosae, and submucosa guarantees a satisfying histopathological diagnosis. The native biopsies can be transported on water-ice if the distance to the pathologist takes no longer than 4–6 h. For long distances, biopsies have to be frozen on dry ice (CO2 –80 °C) and transported in a sufficient amount of dry ice (adapted to the time of transportation). For biopsy processing, the following points are important: a total of 122 to 160 15-m-thick native cryostat serial sections have to be cut per biopsy and distributed on four microscope slides. Forty sections are used for lactic dehydrogenase reactions, 32 for succinic dehydrogenase reactions, and the rest for an acetylcholinesterase (AChE) reaction. An AChE reaction alone is sufficient for the diagnosis of Hirschsprung's disease (HD), but never for IND or other developmental malformations of the submucous and myenteric plexuses. Enzymehistotopochemical reactions allow the assessment of functional parameters. These reactions, in contrast to immunohistochemical staining, offer information about the functional activity of special gut structures, e. g., increased AChE activity in nerve fibers of the rectal wall in HD or a lack of dehydrogenase activity in immature ganglia. 相似文献
4.
The gravity model, a method for analyzing transportation distribution in transportation engineering, was used to explain patient
trips between ten health service regions in a Japanese prefecture. The OD (Origin-Destination) tables were constructed with
zoning by regions, distinguishing between out- and inpatients. The observed trips were determined from the data of a survey
conducted in 1992 that reported the locations of patient residences and chosen medical facilities.
The base values used in the model calculations were the population size of each region and the road distance between the centers
of regions. Problems of intrazonal trip were avoided by setting a mean intrazonal movement distance.
This model was calibrated by the linear regression method with simultaneous validation by the index of correlation coefficients.
The model was found to accurately simulate the effect of distance on the choice of medical facilities and the differences
between the characteristics of in- and out-patients. The population value in use showed the relation not only with demand
but also the supply of clinical services. It was suggested that the model presented here was useful in the allocation of medical
resources and would help explain the relationship between suppliers and consumers of medical services. 相似文献
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《Cor et vasa》2018,60(3):e239-e245
IntroductionA modern treatment of patients with ST segment elevation myocardial infarction (STEMI) is based on a rapid primary percutaneous coronary intervention with direct recanalization of the affected coronary artery (dPCI). The outcome of the treatment depends largely on the pre-hospital care management, which can reduce the total ischaemic time and subsequently improve patient's outlook.AimsThe principal aims of this retrospective study were to assess the development of time intervals related to the pre-hospital care and the effect of the mode of transportation to the cathlab (primary vs secondary) on these intervals in patients with acute STEMI treated by primary PCI in 2008, 2010, 2012, 2014 and 2016.MethodsWe have analysed patients with STEMI treated using PCI within 12 h of symptoms onset. In total, 1250 patients were included. To evaluate the development over the last 8 years, uni- and multivariate analyses were used. Categorical variables were analysed using chi-squared tests while continuous variables were analysed using one-way ANOVA and general linear models. The effect of the year and of mode of transportation on time intervals were studied.ResultsThe time intervals did not significantly differ among years with the exception of 2014 where the reason of the deviation was however not related to the quality of the pre-hospital care. The 120 min limit from the first medical contact to unblocking the affected artery (FMCTB) was met in more than 80% patients (80.8), the recommended limit of 90 min in 55.2% of patients. The key factor affecting the total ischaemic time was however the patients’ choice of the mode of transportation – in patients who opted for the primary route of transportation, i.e., called the ambulance, the intervals were significantly shorter (FMCTB on average by 38.2 min and total ischaemic time by 92.9 min). The principal delays were detected in the patients’ delay (103 min inpatients with primary transportation route, 131 in patients with secondary route) as well as, unfortunately, in the intervals between reporting the patients’ problem to the system and ECG-confirmed diagnosis (26 min if the patient calls ambulance vs 52 min if they present at a general practitioner or outpatient clinic) and subsequent transportation to the cathlab (60 min for primary route, 97 for secondary). The latter two should be in particular targeted and we can see a significant room for improvement here.ConclusionThe time intervals do not vary among individual years (with some exceptions). The route of transportation, which is a patient's choice, on the total ischaemic time is however a crucial and predominant factor affecting the total ischaemic time as well as individual intervals. 相似文献
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肿瘤治疗过程中会出现很多严重的不良反应,如何将药物特异性导向癌细胞就成为了肿瘤治疗中亟需解决的问
题。外泌体是由细胞分泌的、纳米级别的、双层脂质的盘状囊泡结构。正常细胞与肿瘤细胞均可分泌外泌体,供体细胞分泌的
外泌体携带着蛋白质、脂质和核糖核酸(包括microRNA和lncRNA),可直接被同组织内其周围的受体细胞所吸收;同时外泌体
几乎存在于唾液、血液、尿液、脑脊髓液等所有体液中,通过体液运输被不同组织内受体细胞所吸收,为受体细胞的生长提供必
要的营养物质。肿瘤细胞中往往可对外释放出高于正常组织的外泌体,在肿瘤发展过程中外泌体对肿瘤的生长、转移和血管
生成起到重要的作用;同时癌细胞所分泌的外泌体中有着可用来区别与其他细胞外泌体不同的特征性分子,可作为肿瘤临床
诊断的分子标志物,也可作为肿瘤分级、精准治疗及预后评估的重要依据。鉴于此,本文收集国外内相关研究资料,对外泌体
的生物学特征进行总结,并综述了其在临床肿瘤诊断、治疗中的作用及应用潜力,并对外泌体进一步的发展方向进行展望,以
期能为外泌体在临床肿瘤精准治疗中的应用提供理论支持。 相似文献
10.