全文获取类型
收费全文 | 1115312篇 |
免费 | 75989篇 |
国内免费 | 3189篇 |
专业分类
耳鼻咽喉 | 14783篇 |
儿科学 | 34237篇 |
妇产科学 | 30305篇 |
基础医学 | 153474篇 |
口腔科学 | 28688篇 |
临床医学 | 97121篇 |
内科学 | 228080篇 |
皮肤病学 | 22038篇 |
神经病学 | 93259篇 |
特种医学 | 45610篇 |
外国民族医学 | 349篇 |
外科学 | 175762篇 |
综合类 | 21383篇 |
现状与发展 | 1篇 |
一般理论 | 421篇 |
预防医学 | 79895篇 |
眼科学 | 25144篇 |
药学 | 78047篇 |
1篇 | |
中国医学 | 2106篇 |
肿瘤学 | 63786篇 |
出版年
2021年 | 10746篇 |
2019年 | 11058篇 |
2018年 | 14632篇 |
2017年 | 11251篇 |
2016年 | 12182篇 |
2015年 | 13992篇 |
2014年 | 20038篇 |
2013年 | 29607篇 |
2012年 | 41457篇 |
2011年 | 43787篇 |
2010年 | 25845篇 |
2009年 | 24318篇 |
2008年 | 40684篇 |
2007年 | 43045篇 |
2006年 | 42758篇 |
2005年 | 42113篇 |
2004年 | 40164篇 |
2003年 | 38149篇 |
2002年 | 37112篇 |
2001年 | 43139篇 |
2000年 | 43883篇 |
1999年 | 38095篇 |
1998年 | 12487篇 |
1997年 | 11174篇 |
1996年 | 10825篇 |
1995年 | 10026篇 |
1994年 | 9475篇 |
1993年 | 8926篇 |
1992年 | 29081篇 |
1991年 | 27818篇 |
1990年 | 27126篇 |
1989年 | 25998篇 |
1988年 | 24148篇 |
1987年 | 23721篇 |
1986年 | 22816篇 |
1985年 | 21761篇 |
1984年 | 16613篇 |
1983年 | 14184篇 |
1982年 | 9040篇 |
1979年 | 15013篇 |
1978年 | 10663篇 |
1977年 | 9035篇 |
1976年 | 8535篇 |
1975年 | 9238篇 |
1974年 | 10974篇 |
1973年 | 10419篇 |
1972年 | 9818篇 |
1971年 | 9056篇 |
1970年 | 8684篇 |
1969年 | 8099篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Bifid mandibular canal. 总被引:1,自引:0,他引:1
PURPOSE: To determine the incidence and characteristics of bifid mandibular canals. METHODS: A retrospective study was performed using panoramic radiographs of 2012 patients subjected to dental treatment in the Dental Clinic of the Valencia University Dental School (Valencia, Spain) between 1996 and 1999. The goal was to investigate the presence of double mandibular canals. RESULTS: The extraoral panoramic radiographs revealed a total of 7 images suggestive of bifid canals. Mandibular computed tomography revealed the existence of this anatomic variant in 2 of 3 patients. An analysis was performed on the incidence of this type of image in extraoral panoramic radiography, its possible interpretations, and the clinical implications of bifid mandibular canals. CONCLUSIONS: In this study, 0.35% of canals were bifid. All cases were in women. 相似文献
42.
43.
F Pitta T Troosters V S Probst M A Spruit M Decramer R Gosselink 《The European respiratory journal》2006,27(5):1040-1055
Accurate assessment of the amount and intensity of physical activity in daily life is considered very important due to the close relationship between physical activity level, health, disability and mortality. For this reason, assessment of physical activity in daily life has gained interest in recent years, especially in sedentary populations, such as patients with chronic obstructive pulmonary disease (COPD). The present article aims to compare and discuss the two kinds of instruments more commonly used to quantify the amount of physical activity performed by COPD patients in daily life: subjective methods (questionnaires, diaries) and motion sensors (electronic or mechanical methods). Their characteristics are summarised and evidence of their validity, reliability and sensitivity is discussed, when available. Subjective methods have practical value mainly in providing the patients' view on their performance in activities of daily living and functional status. However, care must be taken when using subjective methods to accurately quantify the amount of daily physical activity performed. More accurate information is likely to be available with motion sensors rather than questionnaires. The selection of which motion sensor to use for quantification of physical activity in daily life should depend mainly on the purpose of its use. 相似文献
44.
45.
46.
Abstract The pain of cluster headache attacks is severe, excruciating and selectively responsive to subcutaneous sumatriptan. Serious
cardiovascular events attributed to sumatriptan are extremely rare and have most often been reported in patients at significant
cardiovascular risk, or in overt cardiovascular disease. They also have occurred, however, in patients without evidence of
cardiovascular disease. We describe a 42-year-old man with episodic cluster headache without history of coronary artery disease
who was admitted to our coronary care unit for acute myocardial infarction after 3 h of subcutaneous injection of sumatriptan.
During hospitalisation cluster headache attacks were successfully treated with e.v. indomethacin. 相似文献
47.
C Berg F Bender M Soukup A Geipel R Axt-Fliedner J Breuer U Herberg U Gembruch 《Ultrasound in obstetrics & gynecology》2006,28(7):882-889
OBJECTIVE: To evaluate the prenatal distribution, associated conditions and outcome of the different types of right aortic arch (RAA) detected in fetal life. METHODS: This was a retrospective review of all cases of RAA detected prenatally between 1998 and 2005 in two tertiary referral centers. RESULTS: In the study period 71 cases of RAA were detected; 26 (37%) had RAA with aberrant left subclavian artery, 23 (32%) had RAA with mirror-image branching, 20 (28%) had RAA of unknown type and two (3%) had double aortic arch. While 20/26 cases with RAA and aberrant left subclavian artery were isolated findings, all 23 cases with RAA and mirror-image branching were associated with cardiac defects, namely tetralogy of Fallot (43%) or pulmonary atresia with ventricular septal defect (22%). Of the 20 cases with RAA, 19 of unknown type were associated with heterotaxy syndromes and had additional cardiac malformations and ambiguities of the situs. The two cases with DAA were isolated findings. Seven cases in our series (10%) had a microdeletion 22q11 and these were significantly associated with extracardiac malformations. The outcome in our series depended solely on the associated cardiac and extracardiac malformations, with the exception of one infant with isolated DAA, in whom a surgical correction was warranted. CONCLUSIONS: RAA detected in fetal life is associated frequently with other cardiac/non-cardiac malformations, heterotaxy syndromes and microdeletions 22q11. The associated conditions vary depending on the branching type of the brachiocephalic vessels and the presence of extracardiac malformations. 相似文献
48.
M Bernasconi P N Chhajed F Gambazzi L Bubendorf H Rasch S Kneifel M Tamm 《The European respiratory journal》2006,27(5):889-894
There are no data available combining transbronchial needle aspiration (TBNA) of mediastinal lymph nodes and positron emission tomography (PET) in the staging of nonsmall cell lung cancer (NSCLC). The aim of the current study was to determine if these two methods can enhance the negative predictive value of the individual modality alone, for a specific lymph node station, and if this integrated approach can reduce the number of mediastinoscopies. A total of 113 patients with enlarged mediastinal lymph nodes (> or = 1 cm), who underwent both TBNA and PET scanning, were included. In 51 patients, histopathology, confirmed by surgical lymph node dissection, was compared with PET results and TBNA. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy to detect malignant lymphadenopathy was 68 (13/19), 89 (119/134), 46 (13/28), 95 (119/125) and 86% (132/152) for PET, respectively; 54% (6/11), 100 (53/53), 100 (6/6), 91 (53/58) and 92% (59/64), respectively for TBNA; and 100 (11/11), 94 (50/53), 79 (11/14), 100 (50/50) and 95 (61/64) for combined TBNA and PET, respectively. Combination of transbronchial needle aspiration and positron emission tomography has the potential to allow adequate mediastinal staging of nonsmall cell lung cancer with enlarged lymph nodes in most patients without the need for mediastinoscopy. 相似文献
49.
50.
Neurological Sciences - Spasticity arises from lesions involving the corticoreticulospinal system in the brain, brainstem or spinal cord. Abnormal suprasegmental influences lead to increased spinal... 相似文献