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   9474篇
  免费   463篇
  国内免费   87篇
耳鼻咽喉   70篇
儿科学   223篇
妇产科学   304篇
基础医学   948篇
口腔科学   174篇
临床医学   833篇
内科学   2611篇
皮肤病学   69篇
神经病学   969篇
特种医学   460篇
外科学   1384篇
综合类   26篇
一般理论   3篇
预防医学   380篇
眼科学   136篇
药学   589篇
中国医学   19篇
肿瘤学   826篇
  2024年   18篇
  2023年   62篇
  2022年   161篇
  2021年   285篇
  2020年   153篇
  2019年   240篇
  2018年   303篇
  2017年   226篇
  2016年   248篇
  2015年   282篇
  2014年   381篇
  2013年   472篇
  2012年   747篇
  2011年   722篇
  2010年   377篇
  2009年   399篇
  2008年   584篇
  2007年   563篇
  2006年   572篇
  2005年   585篇
  2004年   517篇
  2003年   493篇
  2002年   440篇
  2001年   97篇
  2000年   89篇
  1999年   93篇
  1998年   88篇
  1997年   88篇
  1996年   71篇
  1995年   57篇
  1994年   51篇
  1993年   33篇
  1992年   55篇
  1991年   43篇
  1990年   42篇
  1989年   23篇
  1988年   41篇
  1987年   29篇
  1986年   36篇
  1985年   36篇
  1984年   23篇
  1983年   25篇
  1982年   26篇
  1981年   24篇
  1980年   18篇
  1979年   11篇
  1978年   12篇
  1977年   10篇
  1974年   8篇
  1972年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
This study investigates the mdm2 gene status and expression in 66 surgically resected human breast carcinomas, with correlations with clinico-pathological and biological data (histological type, grading, steroid receptor status, p53 expression, proliferative activity). Four (7.7 per cent) out of 52 informative cases bear mdm2 gene amplification (four- to ten-fold) and 8 (15.4 per cent) of 52 cases showed borderline amplification (three-fold). Nine (13.6 per cent) out of 66 cases showed strong mdm2 nuclear immunoreactivity. Twenty-seven (40.9 per cent) cases showed isolated mdm2 reactive nuclei. All cases with clear amplification showed a high percentage of mdm2 immunoreactive nuclei. The relationship between gene amplification and mdm2 protein expression is highly significant (P<0.0001). No association was observed between mdm2 gene amplification and any of the considered clinico-pathological and biological parameters, while mdm2 immunoreactivity showed a significant association only with oestrogen receptor immunoreactivity (P=0.009). p53 expression was associated neither with mdm2 gene amplification nor with mdm2 immunoreactivity. It could be tempting to hypothesize that the evaluation of the combined mdm2/p53 immunohistochemical phenotype in human breast carcinoma could give us better prognostic information than the evaluation of the expression of the p53 protein alone.  相似文献   
32.
More than one year has passed since the first cases of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome (SARS)-CoV-2 coronavirus were reported in Wuhan (China), rapidly evolving into a global pandemic. This infectious disease has become a major public health challenge in the world. Unfortunately, to date, no specific antivirals have been proven to be effective against COVID-19, and although a few vaccines are available, the mortality rate is not decreasing but is still increasing. One therapeutic strategy has been focused on infection prevention and control measures. In this regard, the use of nutraceutical supports may play a role against some aspect of the infection, particularly the inflammatory state and the immune system function of patients, thus representing a strategy to control the worst outcomes of this pandemic. For this reason, we performed an overview including meta-analyses and systematic reviews to assess the association among melatonin, vitamin C, vitamin D, zinc supplementation and inflammatory markers using three databases, namely, MEDLINE, PubMed Central and the Cochrane Library of Systematic Reviews. According to the evidence available, an intake of 50,000 IU/month of vitamin D showed efficacy in CRP. An amount of 1 to 2 g per day of vitamin C demonstrated efficacy both in CRP and endothelial function, and a dosage of melatonin ranging from 5 to 25 mg /day showed good evidence of efficacy in CRP, TNF and IL6. A dose of 50 mg/day of elemental zinc supplementation showed positive results in CRP. Based on the data reported in this review, the public health system could consider whether it is possible to supplement the current limited preventive measures through targeted nutraceutical large-scale administration.  相似文献   
33.
Background: The restrictions taken to control the rapid spread of COVID-19 resulted in a sudden, unprecedented change in people’s lifestyle, leading to negative consequences on general health. This study aimed to estimate the impact of such changes on migraine severity during 2020 March–May lockdown. Methods: Patients affected by migraine with or without aura, diagnosed by expert physicians, completed a detailed interview comprehensive of: assessment of migraine characteristics; measure of physical activity (PA) levels; measure of the intake frequency of main Italian foods; the Insomnia Severity Index (ISI) questionnaire investigating sleep disorders. Results: We included 261 patients with a mean age of 44.5 ± 12.3 years. During social distancing, 72 patients (28%) reported a headache worsening, 86 (33%) an improvement, and 103 (39%) a stable headache frequency. A significant decrease of the PA levels during COVID-19 quarantine in the whole study sample was observed (median total metabolic equivalent task (METs) decreased from 1170 to 510; p < 0.001). Additionally, a significant difference was reported on median ISI scores (from 7 to 8; p < 0.001), which were increased in patients who presented a stable or worsening headache. Conclusions: Our study confirmed that the restrictions taken during the pandemic have affected the practice of PA levels and sleep quality in migraine. Hence, PA and sleep quality should be assessed to find strategies for an improvement in quality of life.  相似文献   
34.
Lasers in Medical Science - Childbirth is a great change in woman life because of hormonal, physical and psychological alterations that are associated with this process. Dyspareunia and perineal...  相似文献   
35.
A hospital-based case-control study of renal cell cancer was conducted in northern Italy betwen 1986 and 1989, with 240 cases of renal cell cancer (150 males and 90 females), and 665 controls (445 males and 220 females) chosen on the basis of age, sex, and area of residence. No associations were found between renal cell cancer and: body mass index (BMI); number of cigarettes smoked; age at starting to smoke; years of smoking; consumption of wine, beer, spirits, coffee, decaffeinated coffee; tea; intake of animal protein, fruits, and vegetables; various resproductive factors; hormonal use; sexual habits; sexually transmitted diseases; or selected occupational exposures. The odds ratio (OR) was above unity in smokers (OR=1.34 for 15 cigarettes/day), but the trends in risk with dose or duration were not statistically significant. Significant positive associations were found between renal cell cancer and sources of fat intake, especially margarine (OR for highest vs lowest intake = 1.71), and oils (OR=1.89) whereas carrot intake showed a negative association (OR=0.62). Also, a history of nephrolithiasis and multiple episodes of cystitis showed weak positive associations (OR=2.00, 95 percent confidence interval (CI) 1.07–3.73; and OR=1.60, 95 percent CI 0.95–2.70, respectively).Address reprint requests to Dr Talamini. The work was conducted with the contribution of the Italian Association for Cancer Research, Milan, Italy and the CNR (Italian National Research Council) Applied Projects Oncology (Contract n. 85.02209.44).Drs Talamini, Barón, Barra, Bidoli, Serraino, and Franceschi are in the Epidemiology Unit, Aviano Cancer Center, Via Pedemontana Occ. 33081 Aviano (PN) Italy. At the time of this work, Dr Barón was a visiting biostatistician from the Department of Preventive Medicine and Biometrics, University of Colorado, Health Science Center, CO, funded by the National Cancer Institute (US) and the Italian National Research Council. Dr Franceschi is also chief of the Hormones and Sexual Factors and Cancer Working Group of the European Organization for Cooperation in Cancer Prevention Studies, Bruxelles, Belgium. Drs La Vecchia and Negri are in the Mario Negri Institute for Pharmacological Research, Milan, Italy. Dr La Vecchia is also in the Institute of Social and preventive Medicine, University of Lausanne, Switzerland.  相似文献   
36.
In recent years, several reports have contributed to a growing suspicion that there is immunologic involvement in proliferative intraocular disorders such as proliferative vitreoretinopathy and proliferative diabetic retinopathy. Immune privilege, as in the brain, ovary and testis, also exists in the eye. Therefore, immune responses to unique molecules of the eye, e.g. retinal S-antigen (S-Ag), which the immune system never learns to regard as self, are possible. This study describes the presence of S-Ag, a major soluble photoreceptor protein involved in the visual transduction cascade, in pathological vitreous. We employed indirect immunoblotting, with human retina as substrate, and demonstrated the occurrence of antiretinal antibodies in the sera of a series of patients with proliferative vitreoretinal disorders. Immunoblot analysis of physiological retina and lyophilized S-Ag, revealed this protein as a target molecule of the immunological involvement of the retina. Further immunochemical investigation, however, must clarify whether this autoimmune reaction is the cause, a consequence, or an aggravating factor of the disease. As we come to understand the cellular and molecular mechanism, a new generation of therapeutic strategies may be envisioned.Presented in part at the 18th Meeting of the Club Jules Gonin, Vienna, 1992  相似文献   
37.
The present study aimed to investigate the prevalence and seasonal variation of hypovitaminosis D (defined as serum 25-hydroxyvitamin D level below 30 nmol/l) among healthy subjects and hospitalized patients living in central Italy. We studied 297 subjects, 131 in February 1997 and 166 in July 1997, subdivided into four groups: (a) young healthy blood donors; (b) healthy postmenopausal women; (c) inpatients with various medical diseases and (d) inpatients engaged in long-term rehabilitation programmes because of various neurological disorders. In all subjects and patients serum levels of 25-hydroxyvitamin D were measured by radioimmunoassay. We found a significant seasonal variation (P < 0.0001) of serum 25-hydroxyvitamin D levels, mean values being higher in summer in all groups, except in patients with a longer hospitalization time (group (d)). In each group, a significantly higher prevalence of hypovitaminosis D was found in winter compared with summer time (P < 0.001), being unexpectedly high in postmenopausal women (winter 32% and summer 4.5%); furthermore, in both seasons, inpatients were characterized by the highest incidences of hypovitaminosis, particularly those in group (d) (winter 82.3% and summer 57.8%). The results of the present study emphasize the importance of 25-hydroxyvitamin D measurement, and the need to increase vitamin D intake in Italy; foodstuff fortification and supplement use must be considered in order to prevent negative effects of vitamin D deficiency on skeletal integrity.  相似文献   
38.
(Received for publication on Apr. 28, 1997; accepted on May 15, 1998)  相似文献   
39.
PURPOSE: Loss of a certain amount of cutaneous tissue of the perineal region may be remedied by first intention with creation of cutaneous flaps, thus preventing second intention healing. METHODS: We present three emblematic cases in which the posterior perineal region was reconstructed by means of vertical subcutaneous pedicle flaps, subsequent to cutaneous tissue loss after surgery for extensive condilomas or neoplastic pathologies. RESULTS: Tissue loss was repaired by means of a V-Y type vertical subcutaneous pedicle flap, constructed laterally of the extirpation zone and advanced in a median direction. In all cases, no ischemia or infection of flaps occurred; sphincteral continence and long-term aesthetic results have proved to be satisfactory. CONCLUSIONS: Vertical pedicle subcutaneous flaps are well vascularized, extremely mobile, and easy to perform and have no serious postoperative complications.  相似文献   
40.
The aim of this study was to determine the influence of socio-demographic and professional factors on physicians' attitudes to the terminally ill. Between May 1992 and May 1993, a survey was conducted in the province of Pordenone (north-east, Italy) in order to analyse a number of specific issues, such as emotional involvement, the need for aggressive treatments and the communication of diagnosis and prognosis. After obtaining a list of board-certified physicians from the Medical Association office in Pordenone, a modification of the cancer questionnaire of Haley and Blanchard (QSPT) was mailed to 916 doctors. Of these, 605 (60%; 487 male, 118 female; mean age 41 ± 11 SD) returned the completed questionnaire. Within the group of responders, we identified three main subgroups, according to their type of activity: general practitioners (175, 29%), hospital doctors (235, 39%) and other doctors (195, 32%). In age, sex and activity, the only significant difference between responders and non-responders was age (mean age 41 and 43 years respeetively). Most of the responders (77%) stated that they were able to deal with the terminally ill patient and his/her needs; 44%, however, admitted that patients' anxiety is sometimes unbearable. For the vast majority of the doctors polled (91%), providing a comfortable environment for an incurable patient was more important than pursuing aggressive treatment, but only 44% were convinced of the uselessness of aggressive care. To the question on whether to disclose information about imminent death to allow patients to prepare spiritually, 37% answered No, 38% Yes, and 25% were uncertain. Almost all responders (95%), however, believed in the beneficial effect of hope on the terminally ill. Ourresults suggest that doctors' professional and, most of all, sociodemographic and cultural factors determine the relationship with the patient on both the emotional and the clinical decision-making levels.  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