全文获取类型
收费全文 | 781篇 |
免费 | 44篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 26篇 |
儿科学 | 45篇 |
妇产科学 | 47篇 |
基础医学 | 58篇 |
口腔科学 | 29篇 |
临床医学 | 84篇 |
内科学 | 144篇 |
皮肤病学 | 22篇 |
神经病学 | 65篇 |
特种医学 | 43篇 |
外科学 | 159篇 |
综合类 | 16篇 |
预防医学 | 16篇 |
眼科学 | 26篇 |
药学 | 37篇 |
中国医学 | 2篇 |
肿瘤学 | 11篇 |
出版年
2023年 | 6篇 |
2022年 | 10篇 |
2021年 | 23篇 |
2020年 | 11篇 |
2019年 | 18篇 |
2018年 | 24篇 |
2017年 | 23篇 |
2016年 | 33篇 |
2015年 | 35篇 |
2014年 | 35篇 |
2013年 | 48篇 |
2012年 | 56篇 |
2011年 | 72篇 |
2010年 | 35篇 |
2009年 | 35篇 |
2008年 | 46篇 |
2007年 | 55篇 |
2006年 | 42篇 |
2005年 | 59篇 |
2004年 | 48篇 |
2003年 | 36篇 |
2002年 | 30篇 |
2001年 | 15篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1990年 | 3篇 |
1986年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有830条查询结果,搜索用时 128 毫秒
1.
U. Kuru O. Turan N. Kuru Z. Saglam Y. Ceylan M. Nurluoglu A. Agacfidan 《European journal of clinical microbiology & infectious diseases》1996,15(3):248-251
A total of 5,366 pregnant Turkish women were screened for hepatitis B surface antigen (HBsAg) and 225 (4.2%) of them were found to be positive. Hepatitis B e antigen (HBeAg) was detected in 6.2% of HBsAg-positive pregnant women. The overall prevalence of HBsAg and antibody to HBsAg (anti-HBs) among the spouses, previous children, mothers and first degree relatives of the HBsAg-positive pregnant women was 56%, 49%, 79% and 74% respectively. The prevalence of HBsAg is thus high in pregnant Turkish women with familial clustering of hepatitis B virus infection. 相似文献
2.
The purpose of this investigation was to describe the neural constraints on three-dimensional (3-D) orientations of the eye in space (Es), head in space (Hs), and eye in head (Eh) during visual fixations in the monkey and the control strategies used to implement these constraints during head-free gaze saccades. Dual scleral search coil signals were used to compute 3-D orientation quaternions, two-dimensional (2-D) direction vectors, and 3-D angular velocity vectors for both the eye and head in three monkeys during the following visual tasks: radial to/from center, repetitive horizontal, nonrepetitive oblique, random (wide 2-D range), and random with pin-hole goggles. Although 2-D gaze direction (of Es) was controlled more tightly than the contributing 2-D Hs and Eh components, the torsional standard deviation of Es was greater (mean 3.55 degrees ) than Hs (3.10 degrees ), which in turn was greater than Eh (1.87 degrees ) during random fixations. Thus the 3-D Es range appeared to be the byproduct of Hs and Eh constraints, resulting in a pseudoplanar Es range that was twisted (in orthogonal coordinates) like the zero torsion range of Fick coordinates. The Hs fixation range was similarly Fick-like, whereas the Eh fixation range was quasiplanar. The latter Eh range was maintained through exquisite saccade/slow phase coordination, i.e., during each head movement, multiple anticipatory saccades drove the eye torsionally out of the planar range such that subsequent slow phases drove the eye back toward the fixation range. The Fick-like Hs constraint was maintained by the following strategies: first, during purely vertical/horizontal movements, the head rotated about constantly oriented axes that closely resembled physical Fick gimbals, i.e., about head-fixed horizontal axes and space-fixed vertical axes, respectively (although in 1 animal, the latter constraint was relaxed during repetitive horizontal movements, allowing for trajectory optimization). However, during large oblique movements, head orientation made transient but dramatic departures from the zero-torsion Fick surface, taking the shortest path between two torsionally eccentric fixation points on the surface. Moreover, in the pin-hole goggle task, the head-orientation range flattened significantly, suggesting a task-dependent default strategy similar to Listing's law. These and previous observations suggest two quasi-independent brain stem circuits: an oculomotor 2-D to 3-D transformation that coordinates anticipatory saccades with slow phases to uphold Listing's law, and a flexible "Fick operator" that selects head motor error; both nested within a dynamic gaze feedback loop. 相似文献
3.
4.
5.
Persistent left superior vena cava accompanying congenital heart disease in children: Experience of a tertiary care center 下载免费PDF全文
6.
An 11‐year‐old girl was admitted to pediatric emergency unit with complaints of fatigue and cough. The patient had no previous complaints. There was no history of rheumatic heart disease. The height and duration of the P‐wave was 4 mm and 0.16 seconds, respectively (p mitrale). Echocardiography showed enlarged left atrium (51×61 mm in diameter). Both the anterolateral and posteromedial papillary muscles were directly attached to the anterior and posterior mitral valve leaflets without tendinous chords. The patient was diagnosed with mitral arcade, severe mitral stenosis, and mitral regurgitation. The patient was referred to surgery for replacement of mitral valve. 相似文献
7.
Osman Ozdemir Yasemin Ceylan Cem Hasan Razi Ozben Ceylan Nesibe Andiran 《Pediatric cardiology》2013,34(3):553-559
Patients with asthma develop pulmonary hypertension due to recurrent hypoxia and chronic inflammation, leading to right heart enlargement with ventricular hypertrophy. Patients with severe asthma can experience cor pulmonale later in life, but little is known about ventricular function during the early stages of the disease. This study aimed to investigate ventricular functions in asymptomatic children with asthma as detected by conventional echocardiography and tissue Doppler echocardiography (TDE). Fifty-one pediatric patients (mean age 10.4 ± 2.2 years) with asthma and 46 age- and sex-matched healthy children (mean age 10.9 ± 2.4 years) were studied. All subjects were examined by conventional echocardiography and TDE, and they had pulmonary function tests on spirometry. The right-ventricular (RV) wall was statistically (p = 0.01) thicker among asthmatic patients (4.7 ± 1.5 mm) compared with healthy children (3.6 ± 0.4 mm). However, conventional pulsed-Doppler indices of both ventricles did not differ significantly between asthmatic patients and healthy children (p > 0.05). The results of TDE examining RV diastolic function showed that annular peak velocity during early diastole (E′), annular peak velocity during late diastole (A′) (16.4 ± 1.8 and 5.1 ± 1.4 cm/s, respectively), E′/A′ ratio (3.2 ± 0.7), isovolumetric relaxation time (67.7 ± 10.2 ms) and myocardial performance index (48.1 % ± 7.0 %) of the lateral tricuspid annulus among asthmatic patients differed significantly (p = 0.01) from those of healthy children (13.2 ± 2.3, 8.2 ± 2.0 cm/s, 1.6 ± 0.5, 46.2 ± 8.7 ms, and 42.0 % ± 5.7 %, respectively). Only peak expiratory flow (PEF) rate from the pulmonary function tests was negatively correlated with the E′/A′ ratio of the tricuspid annulus (r = ?0.38, p = 0.01). This study showed that although the findings of clinical and conventional echocardiography were apparently normal in children with asthma, TDE showed subclinical dysfunction of the right ventricle, which is negatively correlated with PEF. These findings signify the diagnostic value of TDE in the early detection and monitoring of such deleterious effects among asthmatic patients. 相似文献
8.
9.