全文获取类型
收费全文 | 6356篇 |
免费 | 385篇 |
国内免费 | 75篇 |
专业分类
耳鼻咽喉 | 126篇 |
儿科学 | 81篇 |
妇产科学 | 118篇 |
基础医学 | 630篇 |
口腔科学 | 201篇 |
临床医学 | 578篇 |
内科学 | 1749篇 |
皮肤病学 | 99篇 |
神经病学 | 735篇 |
特种医学 | 304篇 |
外科学 | 974篇 |
综合类 | 10篇 |
预防医学 | 248篇 |
眼科学 | 51篇 |
药学 | 339篇 |
中国医学 | 11篇 |
肿瘤学 | 562篇 |
出版年
2024年 | 11篇 |
2023年 | 101篇 |
2022年 | 153篇 |
2021年 | 312篇 |
2020年 | 232篇 |
2019年 | 241篇 |
2018年 | 259篇 |
2017年 | 169篇 |
2016年 | 240篇 |
2015年 | 256篇 |
2014年 | 300篇 |
2013年 | 385篇 |
2012年 | 539篇 |
2011年 | 502篇 |
2010年 | 276篇 |
2009年 | 250篇 |
2008年 | 328篇 |
2007年 | 359篇 |
2006年 | 295篇 |
2005年 | 279篇 |
2004年 | 277篇 |
2003年 | 238篇 |
2002年 | 176篇 |
2001年 | 55篇 |
2000年 | 37篇 |
1999年 | 54篇 |
1998年 | 45篇 |
1997年 | 36篇 |
1996年 | 31篇 |
1995年 | 23篇 |
1994年 | 25篇 |
1993年 | 19篇 |
1992年 | 42篇 |
1991年 | 38篇 |
1990年 | 42篇 |
1989年 | 33篇 |
1988年 | 22篇 |
1987年 | 17篇 |
1986年 | 24篇 |
1985年 | 15篇 |
1984年 | 12篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1977年 | 4篇 |
1971年 | 3篇 |
1969年 | 3篇 |
1968年 | 4篇 |
排序方式: 共有6816条查询结果,搜索用时 31 毫秒
11.
Hemoglobin adducts of benzo[a]pyrene diolepoxide in newspaper vendors: association with traffic exhaust 总被引:1,自引:0,他引:1
Pastorelli Roberta; Restano Jolanda; Guanci Marco; Maramonte Monica; Magagnotti Cinzia; Allevi Riccardo; Lauri Davide; Fanelli Roberto; Airoldi Luisa 《Carcinogenesis》1996,17(11):2389-2394
Benzo[a]pyrene diol epoxide adducts with hemoglobin (Hb) weremeasured to detect human exposure to environmental benzo[a]pyrenefrom traffic exhaust. Benzo[a]pyrene tetrahydrotetrols (BPTs)released from Hb after acid hydrolysis were quantitated by gaschromatography-mass spectrometry after immunoaffinity chromatography.Fifty three newspaper vendors were enrolled. The median adductconcentration was 0.3 fmol BPTs/mg Hb in high density traffic-exposedvendors and 相似文献
12.
Megakaryocytic Progenitors Can Be Generated Ex Vivo and Safely Administered to Autologous Peripheral Blood Progenitor Cell Transplant Recipients 总被引:9,自引:1,他引:8
13.
The optical resolution of (R,S)-1-amino-2,3-propanediol was carried out in water with (S)(+)- and (R)(?)-2-(6-methoxy-2-naphthyl)propanoic acid according to Marckwald but using half the quantity of the optically active acid, the other half being constituted by hydrochloric acid. 相似文献
14.
Gross cystic disease of the breast (GCD) is rarely seen after the menopause. Recent work has shown that by measuring electrolytes in the breast cyst fluid (BCF) it is possible to identify two principal classes of cyst, designated Type 1 (K+/Na+ greater than 1.5) and Type 2 (K+/Na+ less than 0.66). A smaller, intermediate class (Type 3) also appears to exist. We measured K+, Na+ and dehydroepiandrosterone sulphate (DHA-S) in 38 BCF samples aspirated from 33 women with GCD who had undergone spontaneous menopause at least 1 yr previously. Statistically significant correlations were found between DHA-S and cations (positive in relation to K+, P less than 0.001; negative in relation to Na+, P less than 0.001). The distribution of cyst types was shifted with respect to that characteristic of cases that occur at an earlier age: whereas Type 1 cysts predominate in menstruating women, Type 2 cysts proved more numerous in the post-menopausal subjects. The difference was statistically validated (P less than 0.001). The results seem to indicate a sharp reduction in high K+, high DHA-S cysts after the menopause, which may be paralleled by a decrease in the associated apocrine metaplasia. In view of the major biochemical differences between Type 1 and Type 2 cysts and of the suggested differences as regards cancer risk, classification of post-menopausal patients with GCD by cyst type is critical prior to any clinical trial or follow-up. 相似文献
15.
Francesco Leo Paolo Scanagatta Pierangelo Baglio Davide Radice Giulia Veronesi Piergiorgio Solli Francesco Petrella Lorenzo Spaggiari 《European journal of cardio-thoracic surgery》2007,31(5):780-782
OBJECTIVE: A higher mortality has been reported after pneumonectomy over the age of 70. The aim of the study was to quantify the additional risk due to age after standard pneumonectomy for lung cancer by a case-control study. METHODS: Our clinical database was reviewed to search for patients aged 70 years or more who underwent standard pneumonectomy for lung cancer between 1998 and 2005. A control group of patients younger than 70 (one case/two controls) was matched for sex, cardiovascular disease, American Association of Anaesthetists score, respiratory function, side of pneumonectomy, induction chemotherapy and stage. Overall mortality and morbidity were compared. Long-term survival data were also analysed. RESULTS: During the considered period, 35 patients aged 70 years or more underwent pneumonectomy (30 males, median age 73 years, 15 right-sided procedures). The control group was composed of 70 patients. The two groups were homogeneous in the variables used for matching. Overall mortality and morbidity were 11.4 and 54.2% in the elderly group as compared to 4.3 and 41.6% in controls (p-value not significant). Elderly patients experienced a higher rate of respiratory complications (25.7%) as compared to controls (8.3%, p=0.01). At univariate analysis, the only risk factor for death was the occurrence of respiratory complications (OR 6.5, CI 1.8-18.2). At multivariate analysis, age >or=70 years (OR 5.36, CI 1.48-19.3) and preoperative chemotherapy (OR 7.65, CI 2.04-28.6) were confirmed as predictors of respiratory complications. Five-year survival was 17.5% in the elderly group and 53.6% in the control group (p=0.003). Elderly patients with a better respiratory function (FEV1>70%) had a 5-year survival of 45.4%. CONCLUSIONS: In the elderly patients, the risk of respiratory complications after pneumonectomy is increased as compared to younger patients with equivalent respiratory function. Age and preoperative chemotherapy are independent risk factors for respiratory complications. A lower mortality and a better long-term survival are obtained in elderly patients with a better respiratory function (FEV1>or=70%). 相似文献
16.
17.
Claudio Babiloni Giuliano Binetti Emanuele Cassetta Gloria Dal Forno Claudio Del Percio Florinda Ferreri Raffaele Ferri Giovanni Frisoni Koichi Hirata Bartolo Lanuzza Carlo Miniussi Davide V Moretti Flavio Nobili Guido Rodriguez Gian Luca Romani Serenella Salinari Paolo M Rossini 《Clinical neurophysiology》2006,117(2):252-268
OBJECTIVE: The present study tested the hypothesis that cortical electroencephalographic (EEG) rhythms. change across normal elderly (Nold), mild cognitive impairment (MCI), and Alzheimer's disease (AD) subjects as a function of the global cognitive level. METHODS: Resting eyes-closed EEG data were recorded in 155 MCI, 193 mild AD, and 126 age-matched Nold subjects. EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). EEG cortical sources were estimated by LORETA. RESULTS: Occipital delta and alpha 1 sources in parietal, occipital, temporal, and 'limbic' areas had an intermediate magnitude in MCI subjects compared to mild AD and Nold subjects. These five EEG sources presented both linear and nonlinear (linear, exponential, logarithmic, and power) correlations with the global cognitive level (as revealed by mini mental state examination score) across all subjects. CONCLUSIONS: Cortical EEG rhythms change in pathological aging as a function of the global cognitive level. SIGNIFICANCE: The present functional data on large populations support the 'transitional hypothesis' of a shadow zone across normality, pre-clinical stage of dementia (MCI), and AD. 相似文献
18.
S P Schinke M A Orlandi R F Schilling C Parms 《Public health reports (Washington, D.C. : 1974)》1992,107(3):323-330
Hispanic and African American adolescents are more likely than white Anglo youth to harbor misconceptions about acquired immunodeficiency syndrome (AIDS) and are also more likely to engage in intravenous drug use and sexual intercourse. This paper describes the development of an AIDS prevention curriculum that uses an interactive videodisc program to teach skills for interventions. Focus group and expert panel studies yielded suggests for intervention vignettes and scenes relevant to Hispanic and African American adolescents. The authors then developed and produced a sample curriculum, specifically designed for Hispanic youth. Content was designed to build knowledge, attitudes, and skills in handling situations where young persons are at risk for human immunodeficiency virus (HIV) infection. The feasibility of the finished pilot product was tested with adolescents and with professionals who serve ethnic and racial minority youth. Adults and Hispanic adolescent viewers rated the videodisc as enjoyable, interesting, and likely to achieve positive effects with the intended target population. Findings suggest that the interactive videodisc is a useful way to interest and help Hispanic adolescents learn ways of reducing their risk of contracting and spreading HIV infection through lifestyle practices. This developmental research in the use of interactive videodisc also provides a basis for further investigation. 相似文献
19.
The aim of the present study was to determine if data on the number and acinar distribution of apoptotic bodies (AB) in normal liver could help in the understanding of cell kinetics in the liver, and the mechanism of early ethanol-induced liver damage. Normal male Sprague-Dawley rats were studied. They had free access to Purina chow and drinking water. Ethanol-treated rats received the drug at increasing concentration in drinking water for 5 weeks. The following parameters were measured: number of AB in the lobule, topographical localization, distance from terminal hepatic veins (THV), i.e. row of hepatocytes concerned, H1 being the closest to the THV. The results show that AB are rare in the normal liver and are always observed in zone 3, next to the THV. Of 149 THV examined, 56 showed one associated AB, exceptionally two. 74% of the AB were confined to the first row of hepatocytes (H1), 21% to H2, 4% to H3, and 1% to H4. In ethanol-treated rats the mean number of AB was 2 or 3 for each THV. 42% were found in H1, 32% in H2, 15% in H3, 7% in H4, and 4% in H5. The data show that AB are not randomly dispersed in normal liver but show a preferential acinar distribution. In addition, most AB are located in the row of liver cells immediately adjacent to the THV. If apoptosis is indeed an expression of physiological cell renewal, these findings support the concept that zone 3 contains older hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
20.
F. Sartucci G. Orlandi U. Bonuccelli D. Borghetti L. Murri C. Orsini L. Domenici V. Porciatti 《Neurological sciences》2006,26(6):395-401
Abstract Idiopathic Parkinson’s disease (IPD) patients have abnormal visual evoked potentials (VEPs) and pattern electroretinograms
(PERGs), attributed to dopaminergic transmission deficiency in visual pathway, probably the retina. VEP abnormalities are
not reported in multiple system atrophy (MSA). The aim of this study was to investigate and compare chromatic (Ch) red-green
(R-G) and blue-yellow (B-Y), and luminance yellow-black (Y-Bk) PERGs in patients with MSA and IPD. We investigated 6 MSA patients
(mean age: 62±7.4 years) not undergoing any pharmacological treatment, as well as 12 early IPD patients (mean age: 60.1±8.3
years) and 12 age-matched normal observers. ChPERGs were recorded monocularly in response to full-field equiluminant R-G,
B-Y and Y-Bk horizontal gratings. In MSA only responses to R-G stimuli showed minimal insignificant changes (slight but not
significant amplitude reduction without any significant latency delay); no significant abnormality was detected for B-Y and
luminance Y-Bk stimuli. By contrast, in IPD all responses were reduced in amplitude and delayed in latency, above all for
B-Y stimuli. Present data indicate that both chromatic and achromatic PERGs are virtually unaffected in MSA, whereas in early
IPD they are clearly impaired, suggesting different pathogenic retinal mechanisms and a useful simple tool for distinguishing
MSA from IPD. 相似文献