全文获取类型
收费全文 | 2404篇 |
免费 | 187篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 24篇 |
儿科学 | 83篇 |
妇产科学 | 19篇 |
基础医学 | 271篇 |
口腔科学 | 63篇 |
临床医学 | 262篇 |
内科学 | 610篇 |
皮肤病学 | 37篇 |
神经病学 | 171篇 |
特种医学 | 108篇 |
外科学 | 307篇 |
综合类 | 42篇 |
一般理论 | 2篇 |
预防医学 | 113篇 |
眼科学 | 69篇 |
药学 | 113篇 |
中国医学 | 7篇 |
肿瘤学 | 312篇 |
出版年
2023年 | 14篇 |
2022年 | 11篇 |
2021年 | 44篇 |
2020年 | 28篇 |
2019年 | 50篇 |
2018年 | 55篇 |
2017年 | 46篇 |
2016年 | 48篇 |
2015年 | 76篇 |
2014年 | 115篇 |
2013年 | 119篇 |
2012年 | 168篇 |
2011年 | 160篇 |
2010年 | 119篇 |
2009年 | 94篇 |
2008年 | 125篇 |
2007年 | 150篇 |
2006年 | 143篇 |
2005年 | 128篇 |
2004年 | 115篇 |
2003年 | 108篇 |
2002年 | 103篇 |
2001年 | 81篇 |
2000年 | 68篇 |
1999年 | 62篇 |
1998年 | 33篇 |
1997年 | 29篇 |
1996年 | 29篇 |
1995年 | 26篇 |
1994年 | 17篇 |
1993年 | 17篇 |
1992年 | 34篇 |
1991年 | 13篇 |
1990年 | 17篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 19篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 14篇 |
1983年 | 7篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1973年 | 5篇 |
1971年 | 8篇 |
1970年 | 5篇 |
1967年 | 5篇 |
排序方式: 共有2613条查询结果,搜索用时 11 毫秒
1.
2.
3.
Peter Reimer Sanjay Saini Ken K. Kwong Mark S. Cohen Ralph Weissleder Thomas J. Brady 《Journal of magnetic resonance imaging : JMRI》1994,4(3):331-335
To develop guidelines for clinical magnetic resonance imaging of the liver, the authors undertook an animal study to investigate the effect of dose and pulse sequence on liver signal intensity in gadopentetate dimeglumine—enhanced echo-planar imaging. Serial imaging of the liver was performed in anesthetized rats after intravenous administration of five different doses (0.01, 0.05, 0.1, 0.2, and 0.5 mmol/kg) of contrast agent, with six different pulse sequences. The results show that gadopentetate dimeglumine—enhanced echo-planar images obtained during the perfusion phase can yield either positive (due to increased T1 relaxation rates) or negative (due to susceptibility-induced increased T2 relaxation rates) liver enhancement depending on choice of pulse sequence and dose. At the current clinically recommended dose of 0.1 mmol/kg, maximal liver signal enhancement was seen with a T1-weighted inversion-recovery sequence, while maximal liver signal diminution was seen with a T2*-weighted gradient-echo sequence. The authors conclude that gadopentetate dimeglumine—enhanced echo-planar imaging can provide T1, T2, and T2* contrast that may be exploited for both lesion detection and lesion characterization. 相似文献
4.
A 16 year old girl with post-streptococcal glomerulonephritis developed acute rheumatic fever 19 days afterwards. Previous publications on concurrent post-streptococcal glomerulonephritis and acute rheumatic fever are reviewed. 相似文献
5.
Terry Kwong MB BS FRACP Senior Fellow Elsa Valderrama MD Assistant Professor of Pediatric Pathology Carole Paley MD Assistant Professor of Pediatrics Norman Ilowite MD Associate Professor of Pediatrics 《Seminars in arthritis and rheumatism》1994,23(6)
Childhood sarcoidosis is a rare disorder with protean manifestations. The case of a child with prolonged fever, hepatosplenomegaly, pancytopenia, and systemic necrotizing vasculitis manifesting as fever, rash and skin infarctions, digital pregangrene, and foot drop is reported. This is the first case of systemic necrotizing vasculitis reported in sarcoidosis. The fulminant course of the disease required treatment with intravenous pulsed cyclophosphamide and high doses of corticosteroids. The spectrum of vasculitis in childhood and adult sarcoidosis is reviewed. 相似文献
6.
Capsaicin-sensitive vagal pulmonary neurones (pulmonary C neurones) play an important role in regulating airway function. During airway inflammation, the level of prostaglandin E2 (PGE2 ) increases in the lungs and airways. PGE2 has been shown to sensitize isolated pulmonary C neurones. The somatosensory correlate of the pulmonary C neurone, the small-diameter nociceptive neurone of the dorsal root ganglion, contains a high percentage of tetrodotoxin-resistant sodium currents (TTX-R I Na ). Therefore, this study was carried out to determine whether these channel currents are involved in the PGE2 -induced sensitization of pulmonary C neurones. We used the perforated patch-clamp technique to study the effects of PGE2 on the TTX-R I Na in acutely cultured capsaicin-sensitive pulmonary neurones that were identified by retrograde labelling with a fluorescent tracer, DiI. We found that the pulmonary neurones sensitive to capsaicin had a higher percentage of TTX-R I Na than that of capsaicin-insensitive pulmonary neurones. PGE2 exposure increased the evoked TTX-R I Na when experiments were performed at both room temperature and at 37°C. Furthermore, stimulation of the adenylyl cyclase/protein kinase A pathway with either forskolin or Sp-5,6-DCl-cBiMPS potentiated the TTX-R I Na in a manner similar to that of PGE2 . We conclude that these modulatory effects of PGE2 on TTX-R I Na play an important role in the sensitization of pulmonary C neurones. 相似文献
7.
H M Cheng O S Singh K K Kwong J Xiong B T Woods T J Brady 《Optometry and vision science》1992,69(9):698-701
We have obtained multislice magnetic resonance (MR) images of the eye and calculated ocular dimensions along the three cardinal axes: antero-posterior (A-P), equatorial, and vertical. We found no difference in the shape of hyperopic (average refractive error: +3.72 D) and emmetropic eyes, both of which had an equatorial diameter longer than the A-P and vertical diameters. Myopic eyes (average refractive error: -6.54 D) were larger than hyperopic eyes, and most had the same spheroelliptical shape as that of the emmetropic and hyperopic eyes. The results suggest that during myopic progression an overall enlargement or a radial volume expansion has occurred. 相似文献
8.
9.
A J Stevenson M P Weber F Todi M Mendonca J D Fenwick L Young E Kwong F Chen P Beaumier S Timmings 《Journal of analytical toxicology》1992,16(2):93-96
The variability in plasma and urine equine procaine measurement between three independent laboratories using current methods led to the development of a sensitive, reliable, and reproducible high-performance liquid chromatographic method. Standardbred mares were administered either a penicillin G procaine preparation intramuscularly or procaine hydrochloride subcutaneously, and blood and urine were collected at defined time intervals. By HPLC the detection limits for procaine in plasma and urine were 1 and 10 ng/mL, respectively. In contrast procaine in plasma could not be detected by GC-NPD, while the urinary detection limit was 50 ng/mL. The concentration of fluoride in the collection tubes and repetitive freeze-thawing modified plasma procaine measurement. Urinary pH was a factor in estimation of urine procaine levels with greater recovery and reproducibility of results at pH 5 as compared to pH 7. This HPLC method provides a simple, sensitive, and reliable quantitation of procaine in equine plasma and urine. 相似文献
10.
Jennifer C. Chen Katrina L. Schmid Brian Brown Marion H. Edwards Bibianna SY Yu John KF Lew 《Clinical & experimental optometry》2003,86(5):323-330
Purpose: Caucasian children with myopia have elevated response accommodative vergence to accommodation (AC/A) ratios. The purpose of this study was twofold: to determine if response AC/A ratios vary with refractive error and with myopic progression rate in Hong Kong Chinese children, and to determine the effect of beta‐adrenergic antagonism with topical timolol application on AC/A ratios. Methods: Thirty children aged eight to 12 years participated in the study. All refractive errors were corrected with spectacle lenses. Accommodative responses were measured using a Shin‐Nippon autorefractor and concurrent changes in vergence were assessed using a vertical prism and a Howell‐Dwyer card at three metres and 0.33 metre. Accommodative demand was altered using plus or minus two dioptre lenses and lens‐ and distance‐induced response AC/A ratios were calculated. Measurements were repeated 30 minutes after the instillation of topical timolol maleate (0.5 per cent). Results: AC/A ratios appeared higher in progressing myopic children but the difference was not statistically significant. Timolol application reduced accommodative convergence (AC) in the stable myopes (reduction = ‐3 ± 1.14A) but not in the emmetropes (0.69 ± 0.9P) or progressing myopes (0.16 ± 0.43A) and this difference between refractive groups was statistically s ignificant (F2,27= 3.766; P= 0.036). However, timolol did not produce a significant change in the accommodative response to positive or negative lenses or response AC/A ratios. Conclusions: We did not find that AC/A ratios in myopic Chinese children were elevated and therefore, it is unlikely that elevated AC/A ratios are responsible for the high levels of myopia that occur in Hong Kong. The finding that timolol reduced AC in the stable myopes suggests that the autonomic control of accommodative convergence in these children may be different from that in emmetropic children and those with progressing myopia. 相似文献