全文获取类型
收费全文 | 1068篇 |
免费 | 47篇 |
国内免费 | 29篇 |
专业分类
儿科学 | 36篇 |
妇产科学 | 8篇 |
基础医学 | 66篇 |
口腔科学 | 38篇 |
临床医学 | 142篇 |
内科学 | 291篇 |
皮肤病学 | 8篇 |
神经病学 | 41篇 |
特种医学 | 131篇 |
外科学 | 138篇 |
综合类 | 32篇 |
预防医学 | 93篇 |
眼科学 | 26篇 |
药学 | 68篇 |
肿瘤学 | 26篇 |
出版年
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 16篇 |
2015年 | 17篇 |
2014年 | 14篇 |
2013年 | 28篇 |
2012年 | 27篇 |
2011年 | 36篇 |
2010年 | 32篇 |
2009年 | 42篇 |
2008年 | 36篇 |
2007年 | 49篇 |
2006年 | 50篇 |
2005年 | 55篇 |
2004年 | 40篇 |
2003年 | 41篇 |
2002年 | 50篇 |
2001年 | 18篇 |
2000年 | 25篇 |
1999年 | 39篇 |
1998年 | 27篇 |
1997年 | 35篇 |
1996年 | 29篇 |
1995年 | 15篇 |
1994年 | 25篇 |
1993年 | 28篇 |
1992年 | 30篇 |
1991年 | 18篇 |
1990年 | 19篇 |
1989年 | 35篇 |
1988年 | 24篇 |
1987年 | 22篇 |
1986年 | 19篇 |
1985年 | 22篇 |
1984年 | 13篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 13篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1975年 | 9篇 |
1973年 | 8篇 |
1972年 | 5篇 |
1969年 | 6篇 |
1926年 | 4篇 |
1925年 | 4篇 |
排序方式: 共有1144条查询结果,搜索用时 15 毫秒
1.
2.
以18-甲基-17β-羟基-17α-乙炔基-雌甾-4-烯-3-酮(18-甲基炔诺酮),17β-羟基-17α-乙缺基-雌甾-4-烯-3-酮(炔诺酮),17β-羟基-17α-乙炔基-雄甾-4-烯-3-酮(妊娠素)和17a-羟基孕甾-4-烯-3,20二酮(17α-羟基黄体酮)为原料,经NaBH,还原、脱水、双键转位和酯化等反应合成一系列3,5-甾二烯化合物,用1HNMR和MS证明了它们的结构。动物筛选结果表明,17β-丙酰氧基-17α-乙炔基-雌甾-3,5-二烯(IVb2有明显的抗早孕活性。中断早期妊娠的作用似与其雌激素活性有关。 相似文献
3.
4.
5.
GD Cramer DJ Allen LJA DiDio W Potvin R Brinker 《Surgical and radiologic anatomy : SRA》1990,12(4):287-290
Summary Accurate volume determination of the encephalic ventricles is of importance in several clinical conditions, including Alzheimer's presenile dementia, schizophrenia, and benign intracranial hypertension. Previous studies have investigated the accuracy with which magnetic resonance imaging (MRI) can be used in clinical practice to evaluate the encephalic ventricles. However, adequate evaluation of pathological conditions depends on a sufficient amount of morphometric data from normal subjects. To begin establishing this data base for normal subjects, we evaluated the MRI scans of 38 subjects found to have no apparent pathology and calculated the ventricular volume in each case by using methods previously developed in our laboratory. The results were then compared with published volumes determined from studies that used either ventricular casts or computerized tomographic scans. The average total ventricular volume for all 38 subjects was 17.4 cm3, while that for males was 16.3 cm3 and that for females was 18.0 cm3. A small but significant correlation was found between age of subject and ventricular volume, with ventricular size increasing with age.
Evaluation du volume des ventricules cérébraux à partir des images obtenues en résonance magnétique nucléaire chez 38 sujets humains
Résumé La détermination exacte du volume des ventricules cérébraux est importante en clinique comme par exemple dans la démence présénile d'Alzheimer, la schizophrénie et l'hypertension intracrânienne bénigne. Des études antérieures ont étudié la fiabilité de la résonance magnétique nucléaire en pratique clinique pour évaluer le volume des ventricules cérébraux. Toutefois une évaluation correcte dans les conditions pathologiques implique une bonne connaissance des données morphométriques du sujet normal. Pour établir ces données sur « le sujet normal », nous avons étudié les coupes obtenues en IRM chez 38 sujets apparemment indemnes de toute pathologie; nous avons calculé le volume ventriculaire dans chaque cas en utilisant des méthodes mises au point auparavant dans notre laboratoire. Les résultats ont été ensuite comparés avec ceux obtenus par d'autres études utilisant soit des moules ventriculaires, soit des coupes tomographiques computérisées. Le volume ventriculaire total moyen chez 38 sujets est de 17,4 cm3, mais il est chez les sujets masculins de 16,3 cm3 et chez les sujets de sexe féminin de 18 cm3. Une corrélation faible mais significative a été trouvée entre l'âge du sujet et le volume ventriculaire, étant entendu que la taille du ventricule augmente avec l'âge.相似文献
6.
7.
H Giedke H Wormstall H T Haffner 《Progress in neuro-psychopharmacology & biological psychiatry》1990,14(1):37-47
1. In 33 patients with a depressive syndrome the effects of partial SD restricted to the 2 hours between 3:00 and 5:00 in the morning was compared to that of no SD (= undisturbed sleep, n = 17) and total SD (n = 16) in a balanced crossover design. 2. Partial SD had a moderate antidepressant effect which is, however, clearly inferior to that of total SD. 3. Reasons for the scarceness of the effect may be an inappropriate timing of this 2-hr SD period (which seems improbable), too short a duration of SD, or the resumption of sleep at 5 o'clock. 4. "Intermediate" SD in the form it was used here represents no therapeutic advantage as we had expected. Its moderate effects lend support to the hypothesis that sleep disturbance is a sign of (mostly insufficient) restorative or self-healing efforts of the depressive organism. 相似文献
8.
9.
Is QT interval a marker of subclinical atherosclerosis in nondiabetic subjects? The Insulin Resistance Atherosclerosis Study (IRAS). 总被引:2,自引:0,他引:2
A Festa R D'Agostino P Rautaharju D H O'Leary M Rewers L Mykk?nen S M Haffner 《Stroke; a journal of cerebral circulation》1999,30(8):1566-1571
BACKGROUND AND PURPOSE: We studied the relationship of heart rate-corrected QT interval with subclinical atherosclerosis, as determined by ultrasonographic measurement of carotid intima-media thickness (IMT) in nondiabetic subjects in the Insulin Resistance Atherosclerosis Study (IRAS). Prolonged heart rate-corrected QT interval is an unfavorable prognostic factor of cardiovascular morbidity and mortality, and QT interval prolongation may be the result of atherosclerosis. METHODS: B-mode ultrasound imaging of the carotid artery IMT was performed in a large, triethnic, nondiabetic population free of clinical coronary artery disease (n=912). QT interval was measured on resting electrocardiograms with use of a computer program and corrected for heart rate with standard equations. RESULTS: IMT of the common carotid artery correlated significantly with heart rate-corrected QT interval duration (r=0.15 for QT(60) and r=0.14 for QTc), whereas no relationship between IMT of the internal carotid artery and QT interval was found (r=-0.01). The association was somewhat stronger in women than in men. In a multiple regression analysis adjusting for demographic variables, the association of common carotid artery IMT to heart rate-corrected QT interval remained highly significant, but adjustment for cardiovascular risk factors weakened the relationship. CONCLUSIONS: We found a significant relation of heart rate-corrected QT interval to carotid atherosclerosis in nondiabetic subjects that was stronger in women and partly mediated by cardiovascular risk factors, including hypertension. QT interval may therefore serve as a marker for clinically undetected ("subclinical") atherosclerotic disease. 相似文献
10.
Terraciano AJ Wang N Schuman JS Haffner G Panjwani N Zhao Z Yang Z 《Current eye research》1999,18(2):73-78
PURPOSE: Sialyl Lewis X (sLex), Lewis X (Lex), and N-acetyllactosamine are carbohydrate chains of neolactoglycoconjugates which are expressed by specific cell types and are important in the functioning of cells within an organism. This study attempts to determine the expression of these glycoconjugates on the conjunctiva, cornea, and trabecular meshwork (TM) of both normal and glaucomatous eyes. METHODS: Frozen anterior segment sections of both normal and glaucomatous human cadaver eyes, as well as rabbit eyes, were stained with a panel of monoclonal antibodies (mAbs) to neolactoglycoconjugates using an Avidin Biotin Peroxidase Complex/Alkaline Phosphatase staining method. RESULTS: SLex characteristically stained both human conjunctival and corneal epithelia in normal (n=5) and glaucomatous (n=5) sections. SLex stained corneal and conjunctival epithelia of glaucomatous eyes much more intensely than normal eyes. Rabbit cornea sections stained for sLex, Lex, and N-acetyllactosamine. However, human cornea only consistently stained with sLex. Normal and glaucomatous human TM sections did not stain for sLex, Lex, or N-acetyllactosamine. CONCLUSIONS: The expression of glycoconjugates with sLex side chains appears to be upregulated in the conjunctival and corneal epithelia of glaucomatous eyes. Distinct species specific differences were noted in Lex and N-acetyllactosamine staining patterns in rabbit and human corneal epithelia. 相似文献