全文获取类型
收费全文 | 109377篇 |
免费 | 6538篇 |
国内免费 | 846篇 |
专业分类
耳鼻咽喉 | 1176篇 |
儿科学 | 3377篇 |
妇产科学 | 2721篇 |
基础医学 | 14378篇 |
口腔科学 | 2587篇 |
临床医学 | 8691篇 |
内科学 | 24648篇 |
皮肤病学 | 2267篇 |
神经病学 | 10394篇 |
特种医学 | 4353篇 |
外国民族医学 | 25篇 |
外科学 | 15251篇 |
综合类 | 1686篇 |
一般理论 | 49篇 |
预防医学 | 6094篇 |
眼科学 | 1689篇 |
药学 | 8486篇 |
3篇 | |
中国医学 | 520篇 |
肿瘤学 | 8366篇 |
出版年
2023年 | 500篇 |
2022年 | 1162篇 |
2021年 | 2072篇 |
2020年 | 1319篇 |
2019年 | 1899篇 |
2018年 | 2356篇 |
2017年 | 1822篇 |
2016年 | 1966篇 |
2015年 | 2250篇 |
2014年 | 2972篇 |
2013年 | 4291篇 |
2012年 | 5836篇 |
2011年 | 6036篇 |
2010年 | 3870篇 |
2009年 | 3395篇 |
2008年 | 5460篇 |
2007年 | 5541篇 |
2006年 | 5372篇 |
2005年 | 5139篇 |
2004年 | 5432篇 |
2003年 | 5215篇 |
2002年 | 5205篇 |
2001年 | 3872篇 |
2000年 | 3782篇 |
1999年 | 3131篇 |
1998年 | 1290篇 |
1997年 | 1020篇 |
1996年 | 928篇 |
1995年 | 890篇 |
1994年 | 789篇 |
1993年 | 772篇 |
1992年 | 1883篇 |
1991年 | 1840篇 |
1990年 | 1576篇 |
1989年 | 1503篇 |
1988年 | 1381篇 |
1987年 | 1245篇 |
1986年 | 1229篇 |
1985年 | 1078篇 |
1984年 | 835篇 |
1983年 | 734篇 |
1982年 | 493篇 |
1981年 | 418篇 |
1979年 | 595篇 |
1978年 | 446篇 |
1975年 | 440篇 |
1974年 | 498篇 |
1973年 | 476篇 |
1972年 | 437篇 |
1971年 | 403篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Federico Venuta Susanna Sciomer Claudio Andreetti Marco Anile Tiziano De Giacomo Matilde Rolla Francesco Fedele Giorgio Furio Coloni 《European journal of cardio-thoracic surgery》2007,32(5):787-790
OBJECTIVE: The effects of major lung resections on cardiac function in the medium and long term have not been thoroughly evaluated. We have studied right heart function with serial Doppler echocardiography in patients undergoing lobectomy and pneumonectomy during 4 years of follow-up after surgery. METHODS: Thirty-six patients undergoing lobectomy and 15 receiving pneumonectomy were evaluated with one- and two-dimensional Doppler standard transthoracic echocardiography before surgery and 1 week, 3 months, 6 months, 1 year, and 4 years postoperatively. We have studied the right midventricular diastolic diameter (RVDD), the right ventricle free wall thickness, the tricuspid valve insufficiency (TVI) and regurgitation jet (TRJ), and the pulmonary artery systolic pressure (PASP). RESULTS: None of the patients died within the first postoperative year. After lobectomy there were no significant modifications of any variable at any time. RVDD progressively increased after pneumonectomy (26.5+/-2.2mm preoperatively vs 34.3+/-7.6 at 4 years; p<0.001). Four years after surgery all patients undergoing pneumonectomy had moderate TVI while only 55% of patients receiving lobectomy showed it (low grade in 50% and moderate in 5%). In this group of patients PASP increased from 26.1+/-2.6 mmHg preoperatively to 34.3+/-7.6 mmHg at 4 years (p<0.00001). CONCLUSIONS: Right ventricle modifications are clearly evident after pneumonectomy and even if they do not show a clear clinical impact they should not be neglected. 相似文献
52.
53.
54.
55.
Dipyridamole and RA-642 inhibit the production of superoxide anion and free radical damage to rat lens. 总被引:1,自引:0,他引:1
J P De la Cruz A Sintas A Moreno J Garcia-Campos F Sanchez de la Cuesta 《Pharmacology & toxicology》1991,69(3):201-204
We studied the effects of dipyridamole and RA-642 on the production of superoxide anions and on oxygen radicals-induced lipid peroxidation in lens tissue homogenates from normal rats and rats given dipyridamole or RA-642 intraperitoneally. Superoxide production was evaluated by phenazine methosulphate (PMS)-induced nitroblue tetrazolium (NBT) reduction and lipid peroxidation by ferrous sulfate and ascorbic acid (FeAs)-induced malondialdehyde (MDA) production. Dipyridamole and RA-642 showed an inhibitory effect on both assays in the experiments with lens tissue homogenates from untreated or treated rats. The extent of inhibition, however, was significantly higher in pyrimidopyrimidinic-treated rats (range of inhibition at different times of incubation was 18% versus 23-57% for dipyridamole and 14% versus 73-80% for RA-642 in the assay of MDA production, and 10% versus 33-37% for dipyridamole and 2.5% versus 11-32% for RA-642 in the assay of NBT reduction). Concentrations of dipyridamole and RA-642 in lens tissue from treated animals could not be determined (less than 0.001 micrograms/mg of tissue). Although both compounds inhibited lipid peroxidation induced by oxygen free radicals, the mechanism of action might include the role of adenosine as a mediator. 相似文献
56.
Ibrahim Fikry Abdelwahab Stefano Bianchi Carlo Martinoli Michael Klein George Hermann 《Journal l'Association canadienne des radiologistes》2006,57(5):278-286
Tuberculosis involving the soft tissue from adjacent bone or joint is well recognized. However, primary tuberculous pyomyositis, tuberculous bursitis, and tuberculous tenosynovitis are rare entities constituting 1% of skeletal tuberculosis. Tuberculous tenosynovitis involves most commonly the tendon sheaths of the hand and wrist, and tuberculous bursitis occurs most commonly around the hip. The greater trochanteric bursa and the greater trochanter are the most frequent sites of tuberculous bursitis. Cases of primary tuberculous pyomyositis and tenosynovitis of the tendons of the ankle and foot are seldom reported in the radiology literature. All imaging modalities-plain radiography, bone scan, computed tomography, and magnetic resonance imaging (MRI)--provide information that is helpful in determining therapy. MRI in particular, with its multiplanar capabilities and superb contrast of soft tissue, can demonstrate the extent of the soft tissue mass and access the adjacent bones and joints. However, MRI has no diagnostic specificity in regard to tuberculosis, and in nonendemic areas, biopsy is strongly recommended. All patients in this review were permanent residents of North America or Western Europe and were immunocompetent. Examples of atypical presentations of the above entities are demonstrated. 相似文献
57.
58.
Contributions of ovarian failure and aging to blood pressure in normotensive perimenopausal women: a mixed longitudinal study 总被引:1,自引:0,他引:1
Epidemiologic studies have shown that blood pressure increases more rapidly in middle-aged women than in middle-aged men. Whether or not ovarian failure contributes to this rapid rise is still not clear. In a follow-up study begun in 1979 and to continue for 10 years, the blood pressure of 193 healthy normotensive perimenopausal women, who lived in the mixed rural/industrial community of Ede, the Netherlands and who were initially aged between 49 and 56 years, was measured annually. During the course of the study, the onset of menopause of each participant could be established. Because of the mixed longitudinal design of the study, it was possible to evaluate the effects of both chronologic aging and time pre- or postmenopause on blood pressure. After the first seven years of follow-up, it was demonstrated that blood pressure did not increase in 168 women whose body weight was relatively stable. After multivariate analyses, systolic as well as diastolic pressure showed a significant negative relation (slope, 1.34 mmHg per year and 0.63 mmHg per year, respectively) with the years since menopause. On the other hand, the observed positive relation (slope, 0.81 mmHg per year) of systolic pressure with chronologic aging was not significant. No consistent association was found between diastolic pressure and chronologic aging. It is concluded that menopause cannot be regarded as a cause of hypertension; on the contrary, ovarian failure appears to have a protective effect on the increase in blood pressure as a result of chronologic aging. on the increase in blood pressure as a result of chronologic aging. 相似文献
59.
60.
Maria Hortal Miguel Estevan Ines Iraola Bremen De Mucio 《International journal of infectious diseases》2007,11(3):273-277
BACKGROUND: Population-based studies on childhood community-acquired pneumonia are scarce in Latin America. Pneumococcal epidemiology is poorly defined, hence the World Health Organization recommended standardized chest radiograph interpretation to improve the approach to bacterial pneumonia. Therefore, our study aimed to estimate the burden of pneumonia in hospitalized children. METHODS: A three-year surveillance study was carried out in four hospitals covering a population of 229,128 inhabitants of whom 10.2% were under five years of age. Clinical records and digitization of their chest radiographs were obtained. A pediatrician and a pediatric radiologist blinded to the clinical diagnosis interpreted the digital images. RESULTS: Of 2034 patients, 826 (40.6%) had consolidated pneumonia, 941 (46.3%) had non-consolidated pneumonia, and 267 (13.1%) had no pneumonia. Children under two years of age predominated (66.9%). The average annual incidence rate for consolidated pneumonia over the three-year study period was 1175/10(5). Eighteen invasive Streptococcus pneumoniae were isolated from patients with consolidated pneumonia and two from those with non-consolidated pneumonia. Respiratory syncytial virus was evenly distributed between both X-ray groups. CONCLUSIONS: Patients younger than two years of age predominated, being the main targets for anti-pneumococcal conjugated vaccines. Incidence rates provided evidence of the burden of consolidated pneumonia for childhood, estimating the potential benefits of vaccination. 相似文献