全文获取类型
收费全文 | 2515篇 |
免费 | 148篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 77篇 |
妇产科学 | 49篇 |
基础医学 | 255篇 |
口腔科学 | 154篇 |
临床医学 | 382篇 |
内科学 | 747篇 |
皮肤病学 | 15篇 |
神经病学 | 101篇 |
特种医学 | 89篇 |
外科学 | 343篇 |
综合类 | 10篇 |
预防医学 | 204篇 |
眼科学 | 13篇 |
药学 | 153篇 |
中国医学 | 1篇 |
肿瘤学 | 67篇 |
出版年
2023年 | 24篇 |
2022年 | 13篇 |
2021年 | 54篇 |
2020年 | 29篇 |
2019年 | 60篇 |
2018年 | 55篇 |
2017年 | 54篇 |
2016年 | 50篇 |
2015年 | 61篇 |
2014年 | 62篇 |
2013年 | 106篇 |
2012年 | 166篇 |
2011年 | 184篇 |
2010年 | 102篇 |
2009年 | 77篇 |
2008年 | 130篇 |
2007年 | 169篇 |
2006年 | 158篇 |
2005年 | 142篇 |
2004年 | 121篇 |
2003年 | 105篇 |
2002年 | 108篇 |
2001年 | 55篇 |
2000年 | 68篇 |
1999年 | 67篇 |
1998年 | 22篇 |
1997年 | 20篇 |
1996年 | 19篇 |
1995年 | 21篇 |
1994年 | 21篇 |
1993年 | 21篇 |
1992年 | 38篇 |
1991年 | 35篇 |
1990年 | 23篇 |
1989年 | 35篇 |
1988年 | 16篇 |
1987年 | 19篇 |
1986年 | 16篇 |
1985年 | 18篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1974年 | 9篇 |
1972年 | 12篇 |
排序方式: 共有2675条查询结果,搜索用时 15 毫秒
1.
2.
J T Knuiman J G Hautvast K F Zwiauer K Widhalm M Desmet G De Backer R R Rahneva V S Petrova M Dahl J Viikari 《European journal of clinical nutrition》1988,42(10):847-855
We have measured systolic and diastolic blood pressure and excretions of sodium, potassium, calcium and magnesium in groups of about 50 8- and 9-year-old boys from 19 European centres using standardized methods for the measurement of blood pressure and collection of urine, and by carrying out all analyses in one laboratory. Weight, height, pulse rate and environmental temperature were also studied. Mean systolic blood pressure ranged from 91 to 105 mm Hg and diastolic blood pressure from 51 to 66 mm Hg. Mean 24-h excretion of sodium was between 91 and 146 mmol/d, that of potassium between 29 and 60 mmol/d, that of calcium between 1.5 and 2.6 mmol/d and that of magnesium between 2.7 and 4.2 mmol/d. Mean sodium excretion tended to be lower and potassium excretion tended to be higher in the boys from the north-western parts of Europe. Relations between either systolic or diastolic blood pressure and electrolyte excretions were generally weak or absent. Most remarkable is that only the association between mean diastolic blood pressure and 24-h magnesium excretion (partial regression coefficient (b +/- s.e., -5.04 +/- 2.08 mm Hg/mmol/d) was statistically significant after adjusting for differences in creatinine excretion and environmental temperature. Mean systolic blood pressure was not significantly related with any of the variables measured. The partial regression coefficient (b +/- s.e.) for diastolic blood pressure on weight was 0.186 +/- 0.062 mm Hg/kg, on height 0.165 +/- 0.056 mm Hg/cm, on pulse rate 0.364 +/- 0.100 mm Hg/beats per min and on outside temperature -0.25 +/- 0.07 mm Hg/degrees C. 相似文献
3.
Thomas B?llingtoft Knudsen Simon Francis Thomsen Charlotte Suppli Ulrik Mogens Fenger Steen Nepper-Christensen Vibeke Backer 《The Journal of asthma》2007,44(4):257-260
BACKGROUND: Season of birth (SOB) has been regarded as a risk factor for atopy. The aim of this study was to explore the relationship between season of birth (SOB) and later development of atopic disease in children and adolescents. METHODS: A total of 1,007 randomly selected subjects, 7 to 17 years of age, who were living in urban Copenhagen, Denmark were studied. All participants were interviewed about respiratory symptoms and possible risk factors for atopic disease. Skin test reactivity, serum total immunoglobulin E (IgE), and airway responsiveness were measured using standard techniques. RESULTS: The overall risk of atopy, as judged by skin test reactivity and serum total IgE, was the same regardless of SOB. On the contrary, asthma was more common in subjects born in the autumn compared with subjects born during the remaining part of the year (12.4% vs. 5.6%), OR = 2.40, 95% CI (1.56-3.94), p < 0.001. This was observed both for atopic asthma OR = 2.41, 95% CI (1.25-4.64), p = 0.007, non-atopic asthma, OR = 2.35, 95% CI (1.14-4.83), p = 0.02, and house dust mite (HDM) sensitive airway hyperresponsiveness, OR = 3.00, 95% CI (1.44-6.24), p = 0.002. Rhinitis and pollen allergy were not significantly related to SOB. CONCLUSIONS: Atopy itself is independent of season of birth, whereas asthma is more prevalent among subjects born during the autumn. Regarding asthma, these results suggest that the first months of life enclose a period of particular vulnerability towards environmental risk factors, especially exposure to aeroallergens like HDM. 相似文献
4.
Antioxidant defence during cardiopulmonary bypass surgery. 总被引:1,自引:0,他引:1
Chris R Luyten Frans J van Overveld Lieve A De Backer Anna M Sadowska Inez E Rodrigus Stefan G De Hert Wilfried A De Backer 《European journal of cardio-thoracic surgery》2005,27(4):611-616
OBJECTIVE: Cardiac surgery may lead to severe oxidative stress due to formation of oxidation products generated during ischemia and reperfusion. We investigated to which extent oxidative stress influences a number of endogenous antioxidants and markers of cellular activation. METHODS: At six time points blood was withdrawn from patients undergoing coronary artery bypass grafting, using the on-pump procedure. RESULTS: Both glutathione peroxidase and superoxide dismutase show a gradual and strong increase in activity during surgery (40 and 30%, respectively), returning to baseline values 24 h after surgery. The total antioxidant capacity has a maximum increase of 60%. Markers of cellular activation, such as eosinophil cationic protein and tryptase also increase during the procedure. CONCLUSION: Cardiac surgery results in systemic inflammation accompanied or caused by severe oxidative stress. The human body has a strong innate oxidative defence screen, which is probably not sufficient to fully compensate for the total amount of oxidative damage. 相似文献
5.
Ronald D. Curran M.D. Constantine Mavroudis M.D. Carl L. Backer M.D. 《Journal of cardiac surgery》1997,12(6):372-379
A bstract Background : Ventricular-to-pulmonary artery conduits in growing patients with congenital heart disease will require replacement from time to time due to somatic growth, neointimal hyperplasia, and pulmonary artery stenosis. The purpose of this article is to review our experience with ascending aortic extension for significant long-segment pulmonary artery stenosis in patients undergoing reoperation for right ventricular-to-pulmonary artery conduit replacement. Methods : From 1989 to 1997, 8 patients had aortic transection, right pulmonary artery augmentation arterioplasty, and aortic interposition graft (Hemashield in 7 and Gore-tex in 1) in association with right ventricular-to-pulmonary artery conduit replacement in 7 patients and completion Fontan operation in 1 patient. Aortic cross-clamp time was 90 ± 34 minutes, and the cardiopulmonary bypass time was 205 ± 37 minutes. Results : All patients survived. In those 7 patients who had conduit replacement, the RV/LV ratio declined from 0.78 ± 0.15 to 0.45 ±; 0.05 postoperatively (P < 0.05). Average length of stay was 8.9 ± 7.2 days. Follow-up range is 18 months to 8 years (mean 4 years). Two complications included cardiac transplantation for pre-existing poor left ventricular function and accelerated conduit stenosis leading to conduit re-replacement. Conclusion : Ascending aortic extension facilitates long-segment pulmonary artery augmentation arterioplasty and enlarges the retroaortic space, preventing future compression restenosis. 相似文献
6.
Pia Hovbrandt Agneta Ståhl Susanne Iwarsson Vibeke Horstmann Gunilla Carlsson 《European journal of ageing》2007,4(4):201-211
Due to decreased functional capacity as well as high environmental demands there is a risk of diminishing activity outside
home in very old age (age 80+). In order to explore differences according to functional limitations (FL) among very old people
with respect to frequency of activity, perceived health, overall perception of neighbourhood environment, and perceived problems
in the pedestrian environment, data derived from a postal questionnaire survey to very old people living in an urban area
in Sweden were used. This explorative study is based on the sub-sample of people aged 80+ who reported outdoor activities
(n = 97). Four groups of respondents with different types of FL were identified: with no FL (n = 23), with only movement-related FL (n = 26), with only perception/cognition-related FL (n = 16), and with both movement- and perception/ cognition-related FL (n = 32). The majority of the respondents reported rather high frequency of activity outside home. When examining differences
between the four groups, the analysis indicated how the complexity of FL and perceived problems in the pedestrian environment
impacted on their activity performance. Persons with both movement- and perception/cognition-related FL were less satisfied
with their frequency of activity, experienced their health more negatively and experienced more problems in the pedestrian
environment than in the other groups. The findings from this study indicate the importance of considering combinations of
FL in creating supportive environments for activity and health. 相似文献
7.
To study the relationship between development of lung function and bronchial responsiveness, we examined 106 subjects recruited from a random sample of 527 subjects, aged 8-18 years, from Copenhagen. Lung function and bronchial responsiveness to inhaled histamine were measured at two occasions, in 1986 and 1988. The participating subjects (n = 106) were divided into three groups: (a) 20 asthmatics with bronchial hyperresponsiveness (BHR), (b) 42 nonasthmatic subjects with BHR in 1986, and (c) 44 controls without BHR. In 1986, FEV1 expressed as percentage of predicted value, was found to be similar in the three groups (91%, 94%, and 99%, respectively). The increase in height during the observation period was found to be 5, 6, and 6 cm, respectively, in the three groups. However, at the second examination, in 1988, FEV1 was found to be significantly reduced in both asthmatics (87%) and nonasthmatic subjects (85%) compared with the controls (103%). In 1988, 16 asthmatics (80%) and 24 (57%) nonasthmatic subjects were found to have BHR, whereas none of the controls were found to have BHR. A multiple regression analysis was used to determine the correlation between change in FEV1 and potential factors of importance. The change in FEV1 was highly correlated with the presence of BHR in 1986, however, no correlation was found between change in FEV1 and change in bronchial responsiveness. In conclusion, nonasthmatic subjects with former BHR showed signs of airflow obstruction and less increase in lung function during growth irrespective of the change in level of bronchial responsiveness, which may suggest a risk for subsequent development of obstructive lung disease. 相似文献
8.
9.
I. Sioen † C. Matthys G. De Backer J. Van Camp† & S. De Henauw 《Journal of human nutrition and dietetics》2007,20(6):580-589
BACKGROUND: Regular seafood consumption is recommended in dietary guidelines. The aim of this study was to investigate the importance of seafood as a nutrient source in adolescents' diet and the extent to which seafood consumption can increase the intake of omega-3 polyunsaturated fatty acids and vitamin D. METHODS: Consumption data recorded during seven consecutive days for 341 adolescents selected in Ghent (Belgium) were used to estimate the intake of vitamin D, linoleic (LA), alpha-linolenic (LNA), arachidonic (AA), eicosapentaenoic (EPA), docosapentaenoic (DPA) and docosahexaenoic (DHA) acid. RESULTS: The adolescents consumed on average 3.21 microg/day vitamin D, 11.7 g/day LA and 1.4 g/day LNA. The mean intakes of AA, EPA, DPA and DHA were 83.2, 55.9, 18.4 and 111.4 mg/day respectively. The major source of vitamin D was fortified margarine. Fats and oils were the main sources for LA and LNA. The intake of AA was mainly contributed by meat, poultry and eggs. Fish and seafood contributed for 84.1%, 59.3% and 64.4% respectively for EPA, DPA and DHA. CONCLUSION: Flemish adolescents would benefit from increased seafood consumption, as this would lead to a higher intake of EPA and DHA as well as of vitamin D. Moreover, replacement of foods rich in saturated fat (SFA) by seafood products can help to reduce SFA intake. 相似文献
10.
A De Backer G C Madern F G A J Hakvoort-Cammel J W Oosterhuis F W J Hazebroek 《Zeitschrift für Kinderchirurgie》2006,16(5):318-322
BACKGROUND: Mediastinal germ cell tumors presenting during childhood are extremely rare. Publications on this entity are very scarce. This paper reports on the clinical presentations, method(s) of treatment, complications, results and outcomes in a series of children with mediastinal germ cell tumors. METHODS: A retrospective chart review of 7 children treated between 1971 and 2001 for mediastinal germ cell tumor was carried out. Age at diagnosis and symptoms were recorded. Each patient's surgical treatment, peri- and postoperative complications, histological staging and final outcome were analysed. RESULTS: The median age of the 4 boys and 3 girls was 3 years (range 21 months-15 years). The most frequent symptoms were respiratory distress, persistent coughing, thoracic pain and anorexia/weight loss. Four patients had histologically benign tumors (mature teratoma). Their sole treatment consisted of complete surgical excision of the tumor and (part of) the thymus using either median sternotomy or left-sided thoracotomy. Recovery was uneventful. No recurrences have been observed. All four are alive with no evidence of disease, between 2.5 and 29 years after treatment. Malignant tumors were observed in three patients (1 yolk sac tumor, 1 choriocarcinoma and 1 malignant teratoma). Treatment consisted of either biopsy or debulking followed by chemotherapy (and radiotherapy in 1 case). Two of them died from uncontrollable metastatic disease. The patient with yolk sac tumor survived; he is now in remission, 4 years after diagnosis. CONCLUSIONS: Both this study and the literature review testify to the extreme rarity of mediastinal germ cell tumors in childhood. Children with this type of tumor usually are severely symptomatic. Histologically benign tumors carry an excellent prognosis provided surgical excision is complete. Histologically malignant tumors, on the other hand, have a worse prognosis. However, the use of platinum-based combination chemotherapy has considerably increased the survival rates. 相似文献