全文获取类型
收费全文 | 899784篇 |
免费 | 62460篇 |
国内免费 | 2339篇 |
专业分类
耳鼻咽喉 | 12474篇 |
儿科学 | 28682篇 |
妇产科学 | 26145篇 |
基础医学 | 126593篇 |
口腔科学 | 24686篇 |
临床医学 | 74797篇 |
内科学 | 183201篇 |
皮肤病学 | 18984篇 |
神经病学 | 71398篇 |
特种医学 | 36515篇 |
外国民族医学 | 336篇 |
外科学 | 142119篇 |
综合类 | 19030篇 |
一般理论 | 247篇 |
预防医学 | 64562篇 |
眼科学 | 20083篇 |
药学 | 63818篇 |
中国医学 | 1798篇 |
肿瘤学 | 49115篇 |
出版年
2018年 | 9059篇 |
2017年 | 7166篇 |
2016年 | 7683篇 |
2015年 | 8729篇 |
2014年 | 12376篇 |
2013年 | 19223篇 |
2012年 | 25673篇 |
2011年 | 27272篇 |
2010年 | 16579篇 |
2009年 | 15792篇 |
2008年 | 26140篇 |
2007年 | 27746篇 |
2006年 | 27925篇 |
2005年 | 27463篇 |
2004年 | 26304篇 |
2003年 | 25477篇 |
2002年 | 25065篇 |
2001年 | 41366篇 |
2000年 | 42557篇 |
1999年 | 36270篇 |
1998年 | 9968篇 |
1997年 | 9149篇 |
1996年 | 9084篇 |
1995年 | 8446篇 |
1994年 | 8081篇 |
1993年 | 7585篇 |
1992年 | 28198篇 |
1991年 | 26979篇 |
1990年 | 26408篇 |
1989年 | 25346篇 |
1988年 | 23553篇 |
1987年 | 23171篇 |
1986年 | 22251篇 |
1985年 | 21152篇 |
1984年 | 15806篇 |
1983年 | 13479篇 |
1982年 | 8088篇 |
1979年 | 14591篇 |
1978年 | 10208篇 |
1977年 | 8627篇 |
1976年 | 8147篇 |
1975年 | 8959篇 |
1974年 | 10697篇 |
1973年 | 10182篇 |
1972年 | 9661篇 |
1971年 | 8917篇 |
1970年 | 8584篇 |
1969年 | 8025篇 |
1968年 | 7684篇 |
1967年 | 7086篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
S F Wong A Lee-Tannock D Amaraddio F Y Chan H D McIntyre 《Ultrasound in obstetrics & gynecology》2006,28(7):934-938
OBJECTIVE: To assess the effect of glucose control on the rate of growth of fetuses in women with pregestational diabetes mellitus (Types 1 and 2). METHODS: All pregestational diabetic women booked at Mater Mothers' Hospital, Brisbane, Australia, between 1 January 1994 and 31 December 2002, were included. Pregnancies with congenital fetal anomalies, multiple pregnancies, and pregnancies terminated prior to 20 weeks' gestation were excluded. Dating scans were performed before 14 weeks' gestation and serial scans were performed at 18, 24, 28, 32 and 36 weeks. Fetal parameters, including biparietal diameter, femur length and abdominal circumference, were recorded. The daily growth rates for biparietal diameter, femur length, and fetal abdominal area were calculated and compared with those in a low-risk (non-diabetic) population. The growth rates in fetuses of women with satisfactory diabetic control (HbA1c < 6.5%) and unsatisfactory control (HbA1c > or = 6.5%) in the three trimesters were compared. RESULTS: A total of 174 diabetic pregnancies were included and a total of 997 ultrasound scans were performed. The growth rates for fetuses of mothers with diabetes mellitus were significantly higher than for those in the low-risk population. The z-scores for biparietal diameter, femur length, and fetal abdominal area were 0.18, 0.59 and 1.44, respectively. Fetuses of diabetic mothers with high HbA1c in the first trimester had significantly greater fetal abdominal area growth rate than those with normal HbA1c (fetal abdominal area z-score of 1.7 vs. 0.75, P = 0.009). Although the fetal abdominal area z-scores in fetuses of diabetic mothers with high HbA1c in the second or third trimesters were also higher than those with normal HbA1c levels, the differences did not reach statistical significance. Maternal obesity did not influence the fetal growth rate. CONCLUSION: The rate of growth of fetuses of diabetic mothers differs from that of the normal population. Growth acceleration persists until the late third trimester. Moreover, periconceptional glucose control appears to have a significant effect on accelerated growth of the fetal abdominal area. 相似文献
32.
33.
D F du Toit 《SADJ》2003,58(9):375-6, 380-3
The tongue (L. lingua; G. glossa) functions as a digestive organ by facilitating the movement of food during mastication and assisting swallowing. Other important functions include speech and taste. The tongue consists of striated muscle and occupies the floor of the mouth. The dorsal mucosal surface consists of stratified squamous epithelium, with numerous papillae and taste buds. The tongue, a voluntary muscular structure, is attached by a fold, called the frenulum, to the floor of the mouth. Typically, between 8 and 12 circumvallate papillae are arranged in an inverted V-shape towards the base of the tongue. This anatomical review focuses on structure, function relationships and diseases affecting the tongue. From a primary oral health care perspective, this overview will facilitate the process of differential diagnosis in persons presenting with vesiculo-bullous, ulcerative, atrophic and cystic disorders of the tongue. Suspicious lesions should be biopsied to rule out carcinoma. 相似文献
34.
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
35.
36.
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
37.
38.
39.
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
40.
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