全文获取类型
收费全文 | 88226篇 |
免费 | 5555篇 |
国内免费 | 1154篇 |
专业分类
耳鼻咽喉 | 726篇 |
儿科学 | 2381篇 |
妇产科学 | 2345篇 |
基础医学 | 10761篇 |
口腔科学 | 1710篇 |
临床医学 | 8231篇 |
内科学 | 19757篇 |
皮肤病学 | 1554篇 |
神经病学 | 8751篇 |
特种医学 | 3130篇 |
外国民族医学 | 2篇 |
外科学 | 11715篇 |
综合类 | 2253篇 |
现状与发展 | 1篇 |
一般理论 | 20篇 |
预防医学 | 5636篇 |
眼科学 | 1335篇 |
药学 | 6560篇 |
9篇 | |
中国医学 | 1044篇 |
肿瘤学 | 7014篇 |
出版年
2024年 | 144篇 |
2023年 | 889篇 |
2022年 | 1970篇 |
2021年 | 3267篇 |
2020年 | 2016篇 |
2019年 | 2497篇 |
2018年 | 2824篇 |
2017年 | 2134篇 |
2016年 | 2319篇 |
2015年 | 2807篇 |
2014年 | 3762篇 |
2013年 | 4685篇 |
2012年 | 6538篇 |
2011年 | 6579篇 |
2010年 | 3603篇 |
2009年 | 3332篇 |
2008年 | 5376篇 |
2007年 | 5309篇 |
2006年 | 4839篇 |
2005年 | 4683篇 |
2004年 | 4074篇 |
2003年 | 3616篇 |
2002年 | 3225篇 |
2001年 | 1629篇 |
2000年 | 1485篇 |
1999年 | 1460篇 |
1998年 | 739篇 |
1997年 | 546篇 |
1996年 | 545篇 |
1995年 | 448篇 |
1994年 | 403篇 |
1993年 | 323篇 |
1992年 | 753篇 |
1991年 | 639篇 |
1990年 | 599篇 |
1989年 | 589篇 |
1988年 | 492篇 |
1987年 | 451篇 |
1986年 | 431篇 |
1985年 | 345篇 |
1984年 | 295篇 |
1983年 | 229篇 |
1982年 | 155篇 |
1981年 | 117篇 |
1979年 | 220篇 |
1978年 | 140篇 |
1977年 | 122篇 |
1974年 | 127篇 |
1973年 | 128篇 |
1972年 | 130篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
E Mazzera A Corno R Di Donato L Ballerini B Marino G Catena C Marcelletti 《The Journal of thoracic and cardiovascular surgery》1988,96(2):321-325
The surgical approach to relief of mitral stenosis in children is still a controversial problem. We describe our experience with four severely symptomatic children in whom a valved conduit from the left atrium to the left ventricle was successfully used to bypass a hypoplastic systemic atrioventricular valve. A left atrial-left ventricular extracardiac conduit was implanted in these patients with a hypoplastic mitral anulus and an adequate left ventricular chamber. There were no early or late deaths. Postoperative cardiac catheterization performed in all patients 1 month after the operation showed reduced size of the left atrium, a reduction of the left atrial-left ventricular gradient from a mean of 14 mm Hg to a mean of 5 mm Hg, and an increase of the left atrial outlet from a mean diameter of 10.7 mm to 28.7 mm (including the diameter of the native mitral valve plus the internal diameter of the valved conduit). The application of this unconventional operation in children with congenital or acquired stenosis of the systemic atrioventricular valve should be considered when the mitral valve obstruction cannot be relieved by conventional valve repair or replacement. Furthermore, the left atrial-left ventricular conduit does not preclude future alternative surgical options. 相似文献
104.
F Contaldo G Di Biase R Lanzetta A Lanzilli M S Simonetti F Fidanza 《International journal for vitamin and nutrition research. Internationale Zeitschrift für Vitamin- und Ern?hrungsforschung. Journal international de vitaminologie et de nutrition》1987,57(2):193-202
Nutritional status (anthropometry, food habits, thiamin and riboflavin status) has been evaluated in 136 (70 males and 66 females) free living healthy elderly individuals (age range 65-69 yrs) from the district of San Carlo Arena that can be considered representative of the sociocultural and economic level of the city of Naples. By assuming as reference values those of middle aged individuals, 50 percent of elderly men and 85 percent of elderly women showed different degree of excess body fat. As far as food habits are concerned legumes, vegetables and fruit daily intake was quite high whilst alcohol consumption was low. Furthermore milk and eggs intake was low and infrequent. Although prevalence of excess body weight was high, total daily energy intake was found to be equal or slightly above dietary recommendations for the elderly. Diet composition showed a high protein intake whilst CHO and fat intake was slightly below recommendations. Micronutrients' intake was insufficient for calcium in 10 percent of both males and females and for iron in 20 percent of men and 40 percent of women. Niacin intake was low in about 50 percent of both men and women. Thiamin nutritional status was found low in 20 percent of men and women and riboflavin status in 40 percent of men and 20 percent of women. In conclusion obesity and overweight are very frequent in an urbanized sample of free living healthy elderly individuals of Naples. On the other hand serum calcium and iron and some vitamin deficiency is not uncommon. The composition of the diet seems to be also poor in some micronutrients. 相似文献
105.
A Di Giulio G Maurizi M A Saletti G Amicosante P Mazzeo A Oratore 《Journal of pharmaceutical and biomedical analysis》1989,7(10):1159-1164
A simple, non-invasive spectrophotometric assay to measure the concentration of some beta-lactam antibiotics in turbid solutions containing liposomes was carried out. Since zero-order spectra gave strong interference because of sample turbidity, derivative spectrophotometry was used to enhance the spectral details. Derivative spectra showed bands in the ultraviolet region due to the presence of the cephalosporin and penicillin beta-lactams. A linear relationship between derivative amplitudes and antibiotic concentration was found when antibiotic-containing liposome solutions were measured. A saturative trend in the liposome-encapsulation was observed. The antibiotic entrapment was lowered by increasing the cholesterol-phospholipid ratio in the mixture used for liposome preparation. After treatment of antibiotic-loaded liposomes with beta-lactamase, a hydrolytic enzyme specific for beta-lactams, the remaining antibiotic concentration decreased significantly, showing that some of the antibiotic was retained on the outer surface of the vesicles. 相似文献
106.
107.
F Meneghini W A Rocca D W Anderson F Grigoletto L Morgante A Reggio G Savettieri R Di Perri 《Journal of clinical epidemiology》1992,45(4):319-331
In a hospital setting in Sicily, we assessed a screening instrument developed for a prevalence survey of parkinsonism, peripheral neuropathies, stroke, and epilepsy. The subjects consisted of (1) hospital patients with any of the above-mentioned diseases, to investigate sensitivity; and (2) hospital visitors free of all these diseases, to investigate specificity. The standard for comparison was a clinical evaluation based on specified criteria. Trained interviewers administered the screening instrument, asking subjects to answer symptom questions and to perform simple physical tasks. For the questions and tasks together, the sensitivity estimates were 100% for parkinsonism (n = 21), 96% for peripheral neuropathies (n = 22), 96% for stroke (n = 22), and 96% for epilepsy (n = 22), while the specificity estimate was 86% (n = 21). Analogous estimates were computed for the set of questions, for the set of tasks, and for each question and task individually. Despite limitations in our approach, we concluded that the screening instrument would be adequate for its intended use. 相似文献
108.
Dieter Ebert Andrea Jaspert Harumi Murata Wolfgang P. Kaschka 《Psychopharmacology》1995,118(2):223-225
The hypothesis was tested that an initial lithium-tricyclic antidepressant (TCA) combination has a better antidepressant effect than standard TCA treatment in non-refractory depression at the beginning of an episode. Twenty bipolar melancholic type depressed inpatients under lithium-TCA treatment were compared with 20 patients with the same diagnosis and TCA-placebo treatment for 5 weeks under double-blind conditions. All patients were male. Initial lithium-TCA treatment reduced depressive symptoms significantly more than antidepressant treatment with TCA and placebo after 5 weeks, but not in weeks 1 or 2. It can be concluded that lithium augmentation of TCA treatment should be started even at the beginning of antidepressant TCA treatment to provide a better treatment response in those patients who will profit from long-term lithium prophylaxis, e.g. bipolar patients with melancholic type depression. 相似文献
109.
M. Silvestri M. Bontempelli M. Giacomelli M. Malerba G. A. Rossi A. Di Stefano A. Rossi F. L. M. Ricciardolo 《Clinical and experimental allergy》2006,36(11):1373-1381
BACKGROUND: Severe asthma is characterized by elevated levels of pro-inflammatory cytokines and neutrophilic inflammation in the airways. Blood cytokines, markers of 'systemic' inflammation, may be a feature of amplified inflammation in severe asthma. OBJECTIVE: To detect differences in IL-8, TNF-alpha, IL-16 and IL-13 levels in the serum(s) of stable severe and mild-moderate asthmatics related to blood leucocytes proportion, airway calibre and exhaled nitric oxide (NO) levels. METHODS: We assessed cytokine serum levels by ELISA and blood leucocyte counts by an alkaline peroxidase method in 20 healthy controls, 22 mild-moderate [forced expiratory volume in 1 s (FEV1)(%pred): 89+/-3] and 14 severe asthmatics [FEV1(%pred): 49+/-2]. RESULTS: IL-8 and TNF-alpha levels were higher in severe asthmatics than in mild-moderate asthmatics or in controls (P<0.05). No differences in IL-16 and IL-13 levels were detected. Severe asthmatics showed higher circulating neutrophil and eosinophil number than controls (P<0.05). In severe asthmatics, exhaled NO levels were superior than in controls (P<0.05), but inferior than in mild-moderate asthmatics (P<0.05). We found positive correlation between TNF-alpha levels and exhaled NO (r=0.67; P=0.01) or circulating neutrophil counts (r=0.57; P=0.03) in severe asthmatics. CONCLUSION: sTNF-alpha and sIL-8 are markers of 'systemic' inflammation in severe asthmatics, in conjunction with augmented circulating neutrophils, suggesting the involvement of neutrophil-derived cytokine pattern in severe asthma. 相似文献
110.
Stefanie Klaffke Andrea A Kuhn Michail Plotkin Holger Amthauer Daniel Harnack Roland Felix Andreas Kupsch 《Movement disorders》2006,21(10):1724-1727
Alterations in presynaptic and postsynaptic dopaminergic system and cerebral glucose metabolism in corticobasal degeneration (CBD) were assessed to evaluate the potential usefulness of different imaging methods for CBD. (123)I-FP-CIT/(123)I-beta-CIT SPECT and (123)I-IBZM SPECT as well as (18)F-FDG PET were performed in eight CBD patients. Decreased presynaptic dopamine transporter binding was found in all CBD patients while D2 receptor binding was reduced in only one patient. (18)F-FDG PET displayed a contralateral hypometabolism in cortical and subcortical areas in seven out of eight patients. Our results demonstrate that glucose metabolism and DAT are reduced, while D2 receptors may be frequently preserved in CBD. 相似文献