全文获取类型
收费全文 | 3444篇 |
免费 | 246篇 |
国内免费 | 29篇 |
专业分类
耳鼻咽喉 | 37篇 |
儿科学 | 115篇 |
妇产科学 | 121篇 |
基础医学 | 604篇 |
口腔科学 | 254篇 |
临床医学 | 244篇 |
内科学 | 735篇 |
皮肤病学 | 132篇 |
神经病学 | 251篇 |
特种医学 | 50篇 |
外科学 | 290篇 |
综合类 | 16篇 |
一般理论 | 2篇 |
预防医学 | 389篇 |
眼科学 | 62篇 |
药学 | 216篇 |
中国医学 | 15篇 |
肿瘤学 | 186篇 |
出版年
2023年 | 34篇 |
2022年 | 91篇 |
2021年 | 180篇 |
2020年 | 79篇 |
2019年 | 117篇 |
2018年 | 162篇 |
2017年 | 95篇 |
2016年 | 104篇 |
2015年 | 132篇 |
2014年 | 179篇 |
2013年 | 195篇 |
2012年 | 248篇 |
2011年 | 303篇 |
2010年 | 171篇 |
2009年 | 130篇 |
2008年 | 206篇 |
2007年 | 216篇 |
2006年 | 178篇 |
2005年 | 150篇 |
2004年 | 156篇 |
2003年 | 145篇 |
2002年 | 105篇 |
2001年 | 27篇 |
2000年 | 33篇 |
1999年 | 21篇 |
1998年 | 20篇 |
1997年 | 17篇 |
1996年 | 14篇 |
1995年 | 11篇 |
1994年 | 13篇 |
1993年 | 12篇 |
1992年 | 23篇 |
1991年 | 17篇 |
1990年 | 13篇 |
1989年 | 17篇 |
1988年 | 7篇 |
1987年 | 11篇 |
1986年 | 8篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 5篇 |
1972年 | 3篇 |
排序方式: 共有3719条查询结果,搜索用时 15 毫秒
1.
2.
3.
Transplacental IgG Subclass Concentrations in Pregnancies at Risk of Haemolytic Disease of the Newborn 总被引:5,自引:0,他引:5
A. Lubenko Marcela Contreras C.H. Rodeck U. Nicolini Julia Savage and H. Chana 《Vox sanguinis》1994,67(3):291-298
The relationship of haemolytic disease of the newborn (HDN) to the transplacental passage of the four IgG subclasses was assessed at varous gestational ages by comparing the maternal and fetal IgG subclass concentrations in 34 pregnancies at risk of HDN with those in 30 pregnancies not at risk. Higher maternal and fetal IgG1 levels were attained in pregnancies at risk of HDN than in pregnancies not at risk. In contrast, a slight decrease in maternal IgG2 and IgG4 levels occurred in pregnancies at risk of HDN, as compared with a slight rise in maternal IgG2 and IgG4 levels in pregnancies not at risk of HDN. Changes in fetal IgG2 and 4 concentrations in either type of pregnancy were very similar, showing only slight increases between the 19th and 34th week of gestation. A slight decrease in maternal IgG3 occurred in both types of pregnancy. In contrast, higher and fairly steady levels of fetal IgG3 were observed in fetuses not at risk of HDN throughout gestation, when compared with those in 'at risk' pregnancies. However, the statistical reliability of these results is not clear since only small numbers of samples were tested and because wide variations in IgG concentrations were observed. The IgG subclass concentrations in 50 paired maternal and cord blood samples were also measured and revealed that IgG1 levels were substantially higher in cord rather than maternal blood; cord and maternal IgG2, 3 and 4 levels, on the other hand, were fairly similar. 相似文献
4.
Marcela Hernández Hoyos Piotr Orłowski Ewa Piątkowska-Janko Piotr Bogorodzki Maciej Orkisz 《International journal of computer assisted radiology and surgery》2006,1(1):51-61
The accuracy of 2D phase contrast (PC) magnetic resonance angiography (MRA) depends on the alignment between the vessels and
the imaging plane. PC MRA imaging of blood flow is challenging when the flow in several vessels is to be evaluated with one
acquisition. For this purpose, semi-automatic determination of the plane most perpendicular to several vessels is proposed
based on centerlines extracted from 3D MRA. Arterial centerlines are extracted from 3D MRA based on iterative estimation-prediction,
multi-scale analysis of image moments, and a second-order shape model. The optimal plane is determined by minimizing misalignment
between its normal vector and the centerlines’ tangent vectors. The method was evaluated on a phantom and on 35 patients,
by seeking the optimal plane for cerebral blood flow quantification simultaneously in internal carotids and vertebral arteries.
In the phantom, difference of orientation and of height between known and calculated planes was 1.2° and 2.5 mm, respectively.
In the patients, all but one centerline were correctly extracted and the misalignment of the plane was within 12° per artery.
Semi-automatic centerline extraction simplifies and automates determination of the plane orthogonal to one vessel, thereby
permitting automatic simultaneous minimization of the misalignment with several vessels in PC MRA. 相似文献
5.
F. M. O. Silva J. E. Vergara‐Parente J. K. N. Gomes M. N. Teixeira R. P. Lima 《Transboundary and Emerging Diseases》2007,54(3):119-122
Serum chemistry analyses represents a fundamental tool for the diagnosis and understanding of diseases in marine mammals. Although several studies are being conducted within the field of clinical pathology, haematological and serum chemistry data for Antillean manatees are deficient. The purpose of this study was to determine serum chemistry values for captive Antillean manatees within the CMA/Ibama facility in Brazil. Serum samples were obtained from five captive adult Antillean manatees fed with seagrass and analysed for aspartate aminotransferase, alanine aminotransferase, bilirubin, alkaline phosphatase, urea, creatinine, glucose, triglycerides, cholesterol, total protein, albumin, globulin, phosphate, chloride, calcium and uric acid. Blood chemistry parameters were determined using a semi‐automatic analyzer. Maximum, minimum, mean and standard deviations were calculated for each serum chemistry parameter. Differences on the values of males and females were verified using an unpaired Student's t‐test. All the parameters analysed were similar between sexes, with exception of AP, which was higher in females (191.43 ± 31.86 U/l). Alanine aminotransferase and uric acid values for Trichechus manatus manatus are reported for the first time in this paper. This study is the first to report serum chemistry parameter values for long‐term captive male and female Antillean manatees. Therefore, the lower values of albumin, phosphate, chloride, cholesterol and triglycerides obtained here highlight the importance of clinical pathology during health monitoring of captive marine mammals. 相似文献
6.
7.
8.
Gaston R Vergara William F Wallace Kenneth R Bennett 《Catheterization and cardiovascular interventions》2007,69(2):300-302
Thromboembolic disease accounts for thousands of hospitalizations every year in the US. Its primary management consists of anticoagulation. However, in certain instances this may be contraindicated or not sufficient. Mechanic occlusion of the inferior vena cava (IVC) becomes then a viable alternative. In this case a 35-year-old man presented with a saddle pulmonary embolus but was unable to be anticoagulated due to intestinal bleed. A removable IVC filter was then placed. The filter spontaneously migrated into the right atrium causing severe tricuspid regurgitation, perforation of the atrial wall, and cardiac tamponade. The device was successfully retrieved percutaneously and the patient discharged from the hospital in stable condition. This case illustrates the potentially lethal complications associated with the use of IVC filters, as well as the possibility to percutaneously recover them from within the right atrium. 相似文献
9.
Emergency surgical procedure for failed methotrexate treatment of cervical pregnancy: a case report.
Andrea Tinelli Antonio Malvasi Daniele Vergara Sergio Casciaro 《The European journal of contraception & reproductive health care》2007,12(4):391-395
Cervical pregnancy (CP) is a rare and dangerous condition, which may cause a massive haemorrhage. Ultrasonographic diagnosis consists of the visualization of the gestational sac and trophoblastic invasion in an endocervical localization. CP treatment modalities include dilatation and curettage (D&C) usually followed by intracervical tamponade, cervicotomy, angiographic embolization, ligation of the uterine arteries, and chemotherapy with methotrexate (MTX). MTX administration is a very appealing therapeutic modality of CP in the first trimester because of its convenience and efficacy. We report a case of unsuccessful treatment of a CP with systemic MTX administration, which led to an emergency surgical procedure for a sudden massive vaginal haemorrhage. A vaginal ligation of the cervical branches of the uterine arteries was carried out, followed by suction curettage, D&C and insertion of an intrauterine sterile tampon that was removed after 48 hours. The patient did not require a blood transfusion. Histological examination of the specimen confirmed the CP. 相似文献
10.