首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   990篇
  免费   77篇
  国内免费   6篇
耳鼻咽喉   7篇
儿科学   43篇
妇产科学   12篇
基础医学   134篇
口腔科学   8篇
临床医学   128篇
内科学   240篇
皮肤病学   1篇
神经病学   132篇
特种医学   23篇
外科学   127篇
综合类   1篇
一般理论   1篇
预防医学   105篇
眼科学   19篇
药学   33篇
肿瘤学   59篇
  2023年   6篇
  2022年   11篇
  2021年   31篇
  2020年   27篇
  2019年   41篇
  2018年   37篇
  2017年   36篇
  2016年   42篇
  2015年   22篇
  2014年   40篇
  2013年   68篇
  2012年   74篇
  2011年   82篇
  2010年   46篇
  2009年   40篇
  2008年   48篇
  2007年   67篇
  2006年   74篇
  2005年   53篇
  2004年   37篇
  2003年   39篇
  2002年   33篇
  2001年   9篇
  2000年   9篇
  1999年   4篇
  1998年   9篇
  1997年   13篇
  1996年   8篇
  1995年   6篇
  1994年   1篇
  1993年   4篇
  1992年   3篇
  1991年   5篇
  1990年   6篇
  1989年   5篇
  1988年   10篇
  1987年   1篇
  1986年   2篇
  1985年   1篇
  1984年   1篇
  1983年   2篇
  1982年   2篇
  1981年   2篇
  1980年   1篇
  1979年   4篇
  1978年   5篇
  1977年   5篇
  1975年   1篇
排序方式: 共有1073条查询结果,搜索用时 15 毫秒
51.
It has been hypothesised that oestrogen exposure in utero influences the risk for breast cancer in adult life. Although several studies report associations between breast cancer and maternal factors associated with birthweight of the offspring - a marker for antenatal oestriol exposure - little is known about the relations between maternal oestrogen levels and these factors per se. We therefore analysed the association between oestriol levels in 188 women in the 17th, 25th, 33rd and 37th weeks of pregnancy, and maternal age, prepregnancy weight, height and pregnancy weight gain.Both maternal prepregnancy body mass index and maternal height were, after controlling for infant birthweight, independently and inversely associated with oestriol levels (P = 0.0021 and P = 0.0006 respectively). We found no association between maternal age or pregnancy weight gain and pregnancy oestriol levels. These findings suggest that the previously reported associations between maternal age and maternal pregnancy weight gain and the offsprings risk of breast cancer are due to factors other than antenatal exposure to oestriol.  相似文献   
52.
PURPOSE: By comparing our old (DP5, in use from 1978 to 1994) and new (Plato, Nucletron) dose planning system, we found that the old system underestimated doses by 20-25%. To study the possible consequences for the patients treated between 1978 and 1994, all who were still alive were invited to undergo an examination with respect to side effects and quality of life (QOL). MATERIALS AND METHODS: The degree of overdosage was calculated by comparing the isodose distribution generated on the two dose planning systems. Eighty-four patients were then invited to undergo an examination with respect to side effects and QOL. The side effects were scored according to the LENT SOMA system and QOL according to European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire-Core 30 (QLQ-C30), and EORTC Quality of Life Questionnaire-Head & Neck 35 (QLQ-H&N35). RESULTS: The mean overdosage of brachytherapy was 19.3%. No association was found between overdosage and side effects or QOL. For implants in the lateral border of the tongue, we found a statistically significant correlation between osteoradionecrosis and the following parameters: linear activity, total activity, dose rate, and extrapolated response dose. By multivariate analysis, only total implanted activity and the use of lead protection during brachytherapy were found to be of prognostic significance with respect to development of osteoradionecrosis. CONCLUSION: The incidence of side effects after brachytherapy at the Norwegian Radium Hospital seems to have been somewhat higher in the period under investigation than at other institutions. There may be several explanations, including the use of external beam radiotherapy before brachytherapy and departure from the Paris system among others. However, the side effects were not associated with the overdosage that was the basis for the study. As opposed to the general consensus of opinion, long-term QOL was found to be worse after brachytherapy than after external beam radiotherapy. This calls for increased awareness and a systematic prospective registration of the long-term side effects of brachytherapy.  相似文献   
53.
The aim of the present study was to evaluate to what extent lifestyle-related variables predict participation for flexible sigmoidoscopy (FS) screening when the compliance is relatively high. During 2001, a randomized sample of 6961 men and women, born between 1946 and 1950, were invited to have a flexible sigmoidoscopy screening examination. Attendees (n = 4111) were asked to fill in a questionnaire focusing on physical activity, body weight, smoking habits and diet. The questionnaire was sent by mail to non-attendees (n = 2628) and a randomized corresponding control group not invited to screening (n = 7000). Sixty-one percent attended for screening. The questionnaire response rate among attendees, non-attendees and controls was 97, 11 and 61%, respectively. Attendees were more physically active (P < 0.001), and showed more adherence to general dietary recommendations, compared with controls. Opposing their healthy exercise and dietary habits, however, attendees were more likely to be moderate smokers compared with controls. The present offer of FS screening, achieving a relatively high compliance rate, may have reached attendees using screening as a supplement to an already healthy lifestyle, but also those who seek amelioration through health checks for risks behaviour that they are perfectly well aware of, such as smoking.  相似文献   
54.
Objective:  We have previously described an association between use of cod liver oil (a dietary n-3 fatty acid supplement) and reduced risk of type 1 diabetes. n-3 fatty acids are ligands for the peroxisome proliferator-activated receptor-γ ( PPARG ), which has recently been implicated in the control of inflammation and possibly autoimmunity. We aimed to estimate the association between the common Pro12Ala polymorphism of PPARG2 and risk of type 1 diabetes, and to test whether there is gene–environment interaction with use of cod liver oil in the first year of life or gene–gene interaction with the established insulin gene ( INS ) and human leukocyte antigen DQ ( HLA-DQ ) genetic susceptibility loci.
Methods:  We designed a population-based case–control study of childhood-onset type 1 diabetes in Norway with information on use of cod liver oil in the first year of life from questionnaires and PPARG2 genotype data for 483 cases and 1520 control subjects. We used logistic regression for analysis.
Results:  The odds ratio for the PPARG2 Ala/Ala or Pro/Ala vs. Pro/Pro genotype and type 1 diabetes was 0.89 (95% CI: 0.69–1.13, p = 0.33). There was no significant interaction with cod liver oil in the first year of life [P (interaction) = 0.35] or with the INS polymorphism [P(interaction) = 0.42].
Conclusions:  Although the association between PPARG2 and type 1 diabetes was not significant, the observed odds ratio was almost identical to that observed in two previous studies and can contribute to meta-analysis indicating a weak but significant association. Our hypothesized interaction between cod liver oil and PPARG2 in reducing type 1 diabetes risk was not supported.  相似文献   
55.

Background  

Sense of coherence (SOC) is a strong determinant of positive health and successful coping. For older people living in the community or staying in a hospital, SOC has been shown to be associated with health-related quality of life (HRQOL). Studies focusing on this aspect among nursing home (NH) residents have been limited. This study investigated the relationship between SOC and HRQOL among older people living in NHs in Bergen, Norway.  相似文献   
56.
Zusammenfassung Im Tierexperiment wurde geprüft, ob an der Shay-Ratte nach 9stündiger Pylorusligatur sich in verschiedenen Parametern Unterschiede ergeben zwischen dem Effekt der trunkulären Vagotomie und der selektiven gastralen Vagotomie. Bezüglich Tonisierung des Magens, Menge des Magensaftes, pH des Sekretes und Acidität konnte kein statistisch signifikanter Unterschied festgestellt werden. Eine nachweisbare Differenz ergab sich aber in der Größe der Stressulcera; die trunkuläre Vagotomie schützt die Shay-Ratte besser vor Geschwüren als die selektive. Durch ergänzende Untersuchungen - Ligatur der Arteria gastrica sinistra, gleichzeitiges Ausführen einer trunkulären und selektiven gastralen Vagotomie -konnte bewiesen werden, daß dieser statistisch signifikante Unterschied auf die vasculäre Skeletierung der kleinen Kurvatur des Magens zurückzuführen ist.
Experiments in animals in connexion with truncal and selective gastric vagotomy in rats
Summary The effects of truncal and selective gastric vagotomy after 9 h ligation of the pylorus were studied on Shay rats. No statistically significant difference was found with regard to gastric tonicity, volume of gastric juice, its pH value, nor with regard to the acidity. However, the size of the stress ulcers showed evident differences; vagotomy of the trunk protects the rat better from developing ulcers than selective vagotomy. By means of additional experiments e.g. ligature of the left gastric artery, truncal and selective gastric vagotomy performed simultaneously, we could demonstrate that this statistically significant difference is due to devascularisation of the lesser curvature of the stomach.
  相似文献   
57.
Adrenaline has been added to local anaesthetic solutions for more than a century. The aim has been to delay the absorption of the local anaesthetic drug and to prolong and enhance its anaesthetic effect, both in peripheral and central neuraxial blockades. The intention in this chapter has been to give up-to-date knowledge about adrenaline as an adjuvant to local anaesthetics and/or opioids in clinical peripheral and central blockades. My own research has focused on optimizing postoperative epidural analgesia by adding adrenaline and/or fentanyl to an epidural mixture with dilute bupivacaine or ropivacaine. The main part of this chapter will therefore focus on the advantages and disadvantages of adrenaline in epidural analgesia. However, recent knowledge about adrenaline in peripheral blockade will also be covered, together with some pharmaceutical comments on the shelf-life of local anaesthetic mixtures containing adrenaline.  相似文献   
58.
This study involved observation of hand-hygiene behaviour and evaluation of the effect of alcohol-based hand disinfection and handwashing with plain liquid soap on microbial flora. The study was performed in a combined medical and surgical intensive care unit. We demonstrated a crude compliance of hand hygiene of 50.4%, which was only performed adequately in 20.8% of cases. Of this group, handwashing and hand-disinfection procedures were performed properly 34.0% and 71.6% of the time, respectively. Hand samples for bacteriological examinations with the glove juice method demonstrated that whilst handwashing was sensitive to the way in which hand hygiene was performed, alcohol-based hand disinfection was less sensitive to such performance. Our study demonstrated that alcohol-based hand disinfection is a robust hand-hygiene method with many advantages in a practical setting. It is very feasible for use in hospital wards.  相似文献   
59.
OBJECTIVES: The aim of this investigation was to study the effect of general practitioners' (GP's) characteristics on two decisions: whether to have the Helicobacter pylori rapid test (HPRT) in the office laboratory and whether to use this test or a similar hospital-based serological test in a typical clinical situation described in a vignette. METHODS: Discrete choice analysis with binary logit models were used to predict the probability that a general practice has the HPRT, as well as the GP's probability of using the HPRT or a similar test in this clinical situation. RESULTS: We found that the number of consultations per week has a positive effect on the probability of having the HPRT, indicating that the size of the practice affects the decision to have such a test in the repertoire. Furthermore, four variables significantly increased the probability of using one of the lab tests: more if located in urban practices, more by solo practitioners, more when the GP stated a high probability for H. pylori associated disease, and more when the GP had the rapid test available in the practice. In our analysis, the remuneration system is endogenous and does not have a significant effect on the two decisions. CONCLUSIONS: Our study demonstrates that characteristics of the GP affect the availability and use of a specific laboratory analysis.  相似文献   
60.
PURPOSE: Mandibulotomy is a recognised surgical approach to tumours of the oral cavity and oropharynx. However, the nature and frequency of complications associated with this procedure varies in many studies. We report our experience with access osteotomies, with special reference to radionecrotic complications. PROCEDURES: A retrospective study of 18 consecutive patients undergoing planned mandibular osteotomies as part of the ablative surgery was performed. Various flaps were used for tissue closure: myocutaneous flap (n = 8), nasolabial flap (n = 1) and radial forearm free vascular flap (n = 6). Primary closure using remaining mucosa was achieved in 3 patients. RESULTS: Complete healing of the osteotomy was noted in 13 patients, and 5 patients (27%) developed major wound healing problems and osteoradionecrosis. Dental problems with resorption of the alveolar bone crest and loosening of the teeth adjacent to the osteotomy were seen in 7 patients (39%). CONCLUSIONS: Adequate soft-tissue closure is as important for a successful outcome as the type of osteotomy and fixation method applied. Extraction of the incisors is recommended for easier and safer tissue adaptation, especially when flaps are used for coverage and the osteotomy site will be included in the radiation field.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号