全文获取类型
收费全文 | 763篇 |
免费 | 46篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 34篇 |
妇产科学 | 9篇 |
基础医学 | 62篇 |
口腔科学 | 34篇 |
临床医学 | 57篇 |
内科学 | 207篇 |
皮肤病学 | 17篇 |
神经病学 | 14篇 |
特种医学 | 106篇 |
外科学 | 78篇 |
综合类 | 26篇 |
一般理论 | 1篇 |
预防医学 | 78篇 |
眼科学 | 4篇 |
药学 | 50篇 |
中国医学 | 2篇 |
肿瘤学 | 35篇 |
出版年
2021年 | 15篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 15篇 |
2015年 | 12篇 |
2014年 | 12篇 |
2013年 | 35篇 |
2012年 | 32篇 |
2011年 | 18篇 |
2010年 | 28篇 |
2009年 | 31篇 |
2008年 | 23篇 |
2007年 | 23篇 |
2006年 | 29篇 |
2005年 | 17篇 |
2004年 | 23篇 |
2003年 | 28篇 |
2002年 | 17篇 |
2001年 | 24篇 |
2000年 | 20篇 |
1999年 | 26篇 |
1998年 | 36篇 |
1997年 | 27篇 |
1996年 | 23篇 |
1995年 | 13篇 |
1994年 | 26篇 |
1993年 | 29篇 |
1992年 | 19篇 |
1991年 | 13篇 |
1990年 | 15篇 |
1989年 | 20篇 |
1988年 | 19篇 |
1987年 | 18篇 |
1986年 | 17篇 |
1985年 | 9篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1975年 | 2篇 |
1970年 | 1篇 |
1957年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有816条查询结果,搜索用时 15 毫秒
51.
Diet and other life-style factors in high and low socio-economic groups (Dutch Nutrition Surveillance System) 总被引:3,自引:0,他引:3
K F Hulshof M R L?wik F J Kok M Wedel H A Brants R J Hermus F ten Hoor 《European journal of clinical nutrition》1991,45(9):441-450
Insight into the occurrence of and the association between certain socio-economic variables and life-style characteristics is necessary for preventive nutrition and health policy. The prevalence of and the interdependencies among these variables were examined in 1930 men and 2204 women aged 19 to 85 who participated in the Dutch National Food Consumption Survey 1987-1988. Dietary data were based on a two-day record. The associations among discrete variables were analysed using log-linear models. Analysis of covariance was used to explore the effects of the aggregate socio-economic status (SES) on dietary intake and anthropometry, whereas differences in food intake and SES were assessed by the non-parametric test of Kruskal and Wallis. In comparison to subjects with a high SES in people with a low SES a higher proportion of smokers (48 vs 32 per cent) was observed, a higher prevalence of obesity (39 vs 28 per cent), a higher percentage of heavy coffee drinkers (greater than six cups per day, 23 vs 17 per cent), and more subjects who skipped breakfast (19 vs 11 per cent). In the highest SES class more subjects used nutritional supplements (18 vs 11 per cent), more subjects followed a dietary rule (five vs two per cent), such as a vegetarian diet, and a higher proportion used more than three alcoholic drinks per day (19 vs 15 per cent). A higher SES was associated with a lower fat intake, but the differences (expressed as per cent of energy intake) were rather small and even absent among women when the contribution of alcohol to energy was not taken into account. In general, dietary intake among subjects in higher SES groups tended to be closer to dietary recommendations. The results indicate that a lower SES is accompanied by a higher prevalence of several indicators of an unhealthy life-style. 相似文献
52.
53.
Background
Hadjelia truncata is a nematode that causes lesions in the gizzard lining of pigeons, which may even lead to death. The aim of this study was to introduce Alphitobius diaperinus as a new intermediate host for Hadjelia truncata.Methods
H. truncata infection was identified in a pigeon flock in Ahvaz City, Khuzestan Province, Iran by performing fecal examination and autopsy. Adult and larval stages of beetles were collected from the litter of pigeon houses, and identified morphologically. The beetle larvae were cultured in a medium, containing feces of the infected pigeons. Nematode larval stages from naturally and experimentally (culturally) infected adult beetles were fed to two groups of pigeonsResults
The collected beetles were identified as Alphitobius diaperinus. Average length and width of the adult beetles were 6.31 mm and 2.88 mm respectively. Infection rates of naturally and experimentally infected beetles with larval stages of the nematode were 66.2% and 45.1% respectively. The adult nematodes collected from gizzards of experimentally infected pigeons were identified as H. truncata. Nematode infection rates in pigeons after feeding the infective larvae collected from naturally and experimentally infected beetles were 44.7% and 32.5% respectively.Conclusion
A. diaperinus can serve as a natural intermediate host for H. truncata. 相似文献54.
M Tavassoli S Javadi R Firozi F Rezaei AR Khezri M Hadian 《Iranian Journal of Parasitology》2012,7(4):110-115
Background
We tried to investigate the hair contamination of pet dogs and farm sheepdog with Toxocara eggs in terms of the different sex and age groups in north-west of Iran (Urmia and its suburbs).Methods
Hair samples were collected from a total of 138 pet and farm sheepdogs from November 2008 to June 2009 in Urmia City and the suburb (West Azerbaijan-Iran) and examined for the presence of T. canis eggs.Results
T. canis eggs found in 60 samples altogether (pet and shepherd dogs) showed a contamination rate of 36.2%. The number of observed T. canis eggs in each microscope field was varied from 1 to > 400. The age of the dog was found a significant factor to influence the prevalence and intensity of contamination, with 82% of all the eggs recovered from puppies (six months and younger). Additionally, the numbers of eggs in farm sheepdogs were significantly higher than pet dogs (P<0.05).Conclusion
This report shows that direct contact with T. canis infected dogs, particularly puppies from shepherd dogs, may pose a serious hazard to human. Besides, as they may harbor a considerable number of eggs on their hair, they can contaminate the soil and the environment. 相似文献55.
Clustering of dietary variables and other lifestyle factors (Dutch Nutritional Surveillance System). 总被引:3,自引:3,他引:3 下载免费PDF全文
K F Hulshof M Wedel M R L?wik F J Kok C Kistemaker R J Hermus F ten Hoor T Ockhuizen 《Journal of epidemiology and community health》1992,46(4):417-424
STUDY OBJECTIVE--The aim was to investigate whether dietary factors cluster in a favourable or unfavourable way and to characterise the groups identified by lifestyle and sociodemographic variables. DESIGN AND SETTING--This cross sectional study was based on data of the 1987-1988 Dutch national food consumption survey (DNFCS), obtained from a panel by a stratified probability sample of the non-institutionalised Dutch population. PARTICIPANTS--3781 adults (1802 males and 1979 females) of the DNFCS, aged 19 to 85 years, were studied. MEASUREMENTS AND MAIN RESULTS--To estimate dietary intake two day food records were used. Lifestyle factors were collected by structured questionnaire and sociodemographic variables were available from panel information. Cluster analysis was used to classify subjects into groups based on similarities in dietary variables. Subsequently, these groups were characterised by sociodemographic and lifestyle factors as well as by the consumption of food groups. Eight clusters were found. In comparison with the guidelines, the dietary quality in four clusters was poor. The cluster with the poorest dietary intake (high intake of fat, cholesterol, and alcohol; low intake of dietary fibre) showed on average a high consumption of animal products (except milk), fats and oils, snacks, and alcoholic beverages, and a low consumption of fruit, potatoes, vegetables, and sugar rich products. Smoking, body mass index, dietary regimen on own initiative, hours of sleep, gender, age, socioeconomic status, and day of the week were found to discriminate among the clusters. CONCLUSIONS--Cluster analysis resulted in substantial differences in mean nutrient intake and seems useful for dietary risk group identification. Undesirable lifestyle habits were interrelated in some clusters, but an exclusive lifestyle for health risk has not been found. 相似文献
56.
AR Genazzani G Sandrini F Facchinetti V Rizzo E Alfonsi G Sances M Calvani G Nappi 《Cephalalgia : an international journal of headache》1986,6(4):241-245
L-Tryptophan (L-TP) has been used in migraine and other pain conditions. The mechanism underlying the analgesic effect is still partly undefined. In this study the effects of subchronic administration of L-5-hydroxy-tryptophan (L-5HTP) (with and without carbidopa) on plasma beta-endorphin (beta-EP) levels and subjective pain threshold and tolerance were investigated in seven healthy volunteers. To measure also an objective indicator for pain, the nociceptive flexion reflex threshold was studied. L-5HTP treatment with and without carbidopa administration increased beta-EP levels significantly (p less than 0.05). L-5HTP plus carbidopa induced an increase in beta-EP significantly (p less than 0.05) higher than that after L-5HTP alone. Neither subjective pain threshold and tolerance nor RIII threshold was modified by either treatment. Our data seem to point to the existence of a complex linkage between plasma opioid levels and pain perception. 相似文献
57.
Peptic ulcer and gastric carcinoma: diagnosis with biphasic radiography compared with fiberoptic endoscopy 总被引:1,自引:0,他引:1
Shaw PC; van Romunde LK; Griffioen G; Janssens AR; Kreuning J; Eilers GA 《Radiology》1987,163(1):39-42
The diagnostic value of biphasic radiographic examination of the stomach and duodenum was compared with that of fiberoptic endoscopy in a prospective, blinded study of 385 patients with dyspepsia. This investigation was directed at gastric malignancies and peptic ulcers. Methodologically there is no absolute standard for a study of this kind because histologic examination is useful for detection of cancer but inadequate for ulcers. As an alternative, kappa indexes and the sensitivity and specificity, as derived by Hui and Walter, were calculated and compared. For the detection of gastric carcinoma, radiographic and endoscopic findings had almost perfect agreement beyond chance. For gastric ulcers, radiography and endoscopy had substantial agreement, which became perfect if small ulcers (less than 5 mm) were excluded. For duodenal ulcers, radiography had a lower sensitivity than endoscopy; this disagreement disappeared if small ulcers were excluded. Both methods have equal merit; choice of the initial diagnostic procedure will therefore depend on cost, discomfort to the patient, and risk of complications. 相似文献
58.
F H van Enckevort C G Sweep P N Span P N Demacker C C Hermsen A R Hermus 《Journal of endocrinological investigation》2001,24(10):786-795
Administration of bacterial lipopolysaccharide (LPS) in rodents induces the release of pro-inflammatory cytokines [tumor necrosis factor (TNF), interleukin (IL)-1, IL-6] and of ACTH and corticosterone. IL-6 is probably an important cytokine in the interaction between the immune system and the hypothalamus-pituitary-adrenal (HPA) axis, but so far the role of IL-6 in lipopolysaccharide (LPS)-induced HPA activation has not been established unequivocally. We examined the effects of intraperitoneal administration of LPS (range 0.25-2000 pg/mouse) on plasma corticosterone, TNFalpha and IL-1alpha levels in IL-6-deficient (IL-6 -/-) and wildtype control (IL-6 +/+) mice. Plasma corticosterone levels increased within one hour in both mouse strains. The corticosterone response was significantly reduced in IL-6 -/- mice, but no differences in TNFalpha or in IL-1alpha plasma levels were found between the two strains. Next, we studied the involvement of IL-1alpha or TNFalpha in the responses to LPS in IL-6 -/- and IL-6 +/+ mice by infusion of recombinant human IL-1 receptor antagonist (IL-1ra), or by injection of anti-TNFalpha antibodies. Pretreatment with IL-1ra or with anti-TNFalpha did not affect the corticosterone response to LPS, neither in IL-6 -/-, nor in IL-6 +/+ mice. Our data suggest that in the stimulation of the HPA axis by LPS in mice blockade of either IL-1alpha or TNFalpha may be compensated for by other mediators. The reduced adrenal response after LPS administration found in IL-6 -/- mice indicates a distinct role for IL-6 in the activation of the HPA axis by LPS. 相似文献
59.
60.
ANDERSON G; COLES ET; CRANE M; DOUGLAS AC; GIBBS AR; GEDDES DM; PEEL ET; WOOD JB 《QJM : monthly journal of the Association of Physicians》1992,83(3):427-438
In order to describe the British experience of Wegener's granuiomatosisHospital Activity Analysis was used to collect cases diagnosedin England, Wales and Scotland between 1975 and 1985. Wherepossible clinical details, histological material and chest radiographswere obtained. Two hundred and sixty five patients were consideredto have Wegener's granuiomatosis. In 109 a single pathologistconfirmed the diagnosis by finding both granulomas and vasculitisin biopsy material. The diagnosis was made on clinical groundsor clinical grounds together with histological diagnosis inthe local hospital in 156 patients. Wegener's granuiomatosiswas confined to the lung or upper respiratory tract in 22 percent of patients and renal disease occurred in 58 per cent.Laboratory tests showed a pattern of mild anaemia, polymorphleucocytosis, eosinophilia and an elevated ESR and hypergammaglobulinaemia,with no specific pattern of changes. Histological confirmation was most frequently obtained by examinationof nasal biopsy specimens, but multiple biopsies were oftenrequired. Renal biopsies showed focal proliferative glomerulonephritisbut granulomatous glomerulonephritis was uncommon. Of availablechest radiographs 61 per cent were abnormal, large opacitiesbeing most common. Small irregular opacities were found lessoften and other abnormalities were uncommon. Treatment varied widely and 10 per cent of patients receivedno drug therapy. This large series illustrates that even withoutspecific treatment, patients with Wegener's granuiomatosis cansurvive for several years and with modern treatment survivalfor more than a decade is possible. Conclusions about the effectivenessof the various therapies cannot be drawn from this restrospectivestudy. Renal failure and disseminated vasculities were the commonestcauses of death; death was considered to result from complicationsof treatment with cytotoxic drugs or prednisolone in 6 per centof patients. 相似文献