全文获取类型
收费全文 | 1512篇 |
免费 | 88篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 100篇 |
妇产科学 | 19篇 |
基础医学 | 154篇 |
口腔科学 | 25篇 |
临床医学 | 172篇 |
内科学 | 272篇 |
皮肤病学 | 20篇 |
神经病学 | 93篇 |
特种医学 | 312篇 |
外科学 | 116篇 |
综合类 | 10篇 |
预防医学 | 86篇 |
眼科学 | 50篇 |
药学 | 81篇 |
肿瘤学 | 93篇 |
出版年
2023年 | 5篇 |
2021年 | 16篇 |
2020年 | 8篇 |
2019年 | 13篇 |
2018年 | 23篇 |
2017年 | 8篇 |
2016年 | 13篇 |
2015年 | 27篇 |
2014年 | 29篇 |
2013年 | 33篇 |
2012年 | 26篇 |
2011年 | 27篇 |
2010年 | 33篇 |
2009年 | 35篇 |
2008年 | 23篇 |
2007年 | 42篇 |
2006年 | 39篇 |
2005年 | 33篇 |
2004年 | 28篇 |
2003年 | 24篇 |
2002年 | 25篇 |
2001年 | 31篇 |
2000年 | 18篇 |
1999年 | 39篇 |
1998年 | 96篇 |
1997年 | 71篇 |
1996年 | 81篇 |
1995年 | 56篇 |
1994年 | 58篇 |
1993年 | 67篇 |
1992年 | 27篇 |
1991年 | 19篇 |
1990年 | 28篇 |
1989年 | 50篇 |
1988年 | 45篇 |
1987年 | 49篇 |
1986年 | 43篇 |
1985年 | 45篇 |
1984年 | 30篇 |
1983年 | 24篇 |
1982年 | 28篇 |
1981年 | 24篇 |
1980年 | 32篇 |
1979年 | 14篇 |
1978年 | 21篇 |
1977年 | 22篇 |
1976年 | 25篇 |
1975年 | 19篇 |
1974年 | 6篇 |
1973年 | 7篇 |
排序方式: 共有1611条查询结果,搜索用时 15 毫秒
61.
JR Skinner AG Stuart J O'Sullivan A Heads RJ Boys S Hunter 《Archives of disease in childhood》1993,69(2):216-220
Doppler and direct measurements of right ventricle to right atrial pressure drop were made during cardiac catheterisation on 28 occasions in 26 infants with congenital heart disease. Age was 10 days to 12 months (median 4.5 months), and weight was 3.1 to 9.0 kg (median 4.7 kg). We measured peak velocity of tricuspid regurgitation by continuous wave Doppler, and the pressure drop was calculated using the modified Bernoulli equation (delta p = 4v2). There was a high correlation (r = 0.95) between direct and Doppler measurements. Doppler values tended to underestimate the right ventricle to right atrial pressure drop, but this was not of clinical significance (mean 2 mm Hg). The 95% confidence interval for the Doppler velocity was -0.41 to +0.26 m/sec, and was consistent across the range of pressures studied. Variability between observers was tested, by two observers performing sequential paired examinations on 16 newborn babies with tricuspid regurgitation. The coefficient of repeatability was 6.3 mm Hg (95% confidence interval 4.7 to 9.5 mm Hg) or 0.26 m/sec (0.18 to 0.50 m/sec). This method of right ventricular pressure estimation, validated previously only in older children and adults, is a reproducible and accurate technique in infants with tricuspid regurgitation. 相似文献
62.
A O'Meara W Tormey RJ FitzGerald M Fitzgibbon D Kenny 《Acta paediatrica (Oslo, Norway : 1992)》1994,83(1):88-92
O'Meara A, Tormey W, Fitz Gerald RJ, Fitzgibbon M, Kenny D. Interpretation of random urinary catecholamines and their metabolites in neuroblastoma. Acta Paediatr 1994;83:88–92. Stockholm. ISSN 0803–5253
This study reports experience in the estimation of urinary catecholamines (uCATs) and their metabolites in the diagnosis and follow-up of neuroblastoma. Random urine samples were assayed for dopamine, noradrenaline and adrenaline, together with their metabolites 4-hydroxy 3-methoxyman-delic acid (HMMA) and homovanillic acid (HVA), using HPLC with electrochemical detection. Twenty of 21 patients had elevation of one or more uCATs metabolites at diagnosis. Patients were monitored serially from diagnosis and, in those patients who had delayed resection of primary tumour (n=13), particular attention was paid to levels at the pre-surgical evaluation as an indicator of persistence of viable disease at the time of surgery; dopamine proved to be the most accurate indicator of persistent disease at this time. Five of these patients developed recurrent disease, 4 of whom had elevation of two or more uCATs metabolites at the time of relapse. Several conclusions can be drawn from this study: (a) results for HMMA, HVA and dopamine in random urine samples will detect all but the most biochemically immature or inert tumours; (b) dopamine may be the most reliable indicator of persistent disease and (c) noradrenaline and adrenaline measurements were of little benefit. As results are Expressed in relation to urinary creatinine, excretion of which may be affected by dietary protein and is therefore not constant, borderline results should be repeated. 相似文献
This study reports experience in the estimation of urinary catecholamines (uCATs) and their metabolites in the diagnosis and follow-up of neuroblastoma. Random urine samples were assayed for dopamine, noradrenaline and adrenaline, together with their metabolites 4-hydroxy 3-methoxyman-delic acid (HMMA) and homovanillic acid (HVA), using HPLC with electrochemical detection. Twenty of 21 patients had elevation of one or more uCATs metabolites at diagnosis. Patients were monitored serially from diagnosis and, in those patients who had delayed resection of primary tumour (n=13), particular attention was paid to levels at the pre-surgical evaluation as an indicator of persistence of viable disease at the time of surgery; dopamine proved to be the most accurate indicator of persistent disease at this time. Five of these patients developed recurrent disease, 4 of whom had elevation of two or more uCATs metabolites at the time of relapse. Several conclusions can be drawn from this study: (a) results for HMMA, HVA and dopamine in random urine samples will detect all but the most biochemically immature or inert tumours; (b) dopamine may be the most reliable indicator of persistent disease and (c) noradrenaline and adrenaline measurements were of little benefit. As results are Expressed in relation to urinary creatinine, excretion of which may be affected by dietary protein and is therefore not constant, borderline results should be repeated. 相似文献
63.
A 4 year old girl treated with a standard chemotherapy protocol for acute lymphoblastic leukaemia developed hepatic candidosis during the consolidation phase. This relapsed after a prolonged course of amphotericin B and flucytosine. An eight week course of liposomal amphotericin produced a marked clinical improvement which was sustained for one year. A subsequent relapse was associated with transformation to myelodysplastic leukaemia. 相似文献
64.
It is imperative to know the details of the anatomy of the nose before understanding any surgical procedure performed on the nose. The details presented in this article should help the experienced and the novice surgeon accomplish the difficult task of a rhinoplasty. 相似文献
65.
M N Greco W E Hageman E T Powell J J Tighe F J Persico 《Journal of medicinal chemistry》1992,35(17):3180-3183
A novel series of N-[(2-benzothiazolylthio)alkyl]-N'-hydroxyurea derivatives (9-25) was synthesized and evaluated for biological activity as inhibitors of 5-lipoxygenase both in vivo (mouse zymosan peritonitis assay) and in vitro (Ca2+ ionophore-stimulated human peripheral blood leukocyte model). The compounds of this series were based on the corresponding hydroxamic acid derivatives (1, 3, 4, and 5) which were moderately active in vitro but inactive in vivo. A number of compounds in the hydroxyurea series exhibited oral activity for 5-lipoxygenase inhibition. Results of studies relating structure to in vivo and in vitro 5-lipoxygenase activity are reported. 相似文献
66.
67.
A. J. M. Balm P. C. Hageman M. H. van Doornewaard E. M. Groeneveld D. Ivanyi 《European archives of oto-rhino-laryngology》1996,253(4-5):227-233
Cytokeratin (CK) expression was studied in squamous cell carcinomas of different subsites in the head and neck by using cryostat sections from 27 head and neck squamous cell carcinomas (HNSCCs) and 6 cell lines established from HNSCC. All tissues were analyzed immunohistochemically with a panel of monospecific anti-keratin monoclonal antibodies. Most carcinomas recapitulated the expression pattern of keratins present in the basal layer of normal epithelium from the site of tumor origin. Regional differences in the expression of simple-epithelial type of keratins in stratified (pseudostratified) epithelia were to a large extent repeated in corresponding carcinomas. In the present study, localization of various keratins were surveyed and CK 18 specific monoclonal antibodies were specifically used to distinguish SCCs of the larynx or hypopharynx from SCCs of the oral cavity. CK 18 staining of almost all tumor cells was detected in 11 of 12 SCCs of the larynx and hypopharynx, but was only detected sporadically in 3 of 9 SCCs of the oral cavity. The present results show that CK 18 typing might be useful for distinguishing sites of origin of various HNSCCs. Findings also indicate that CK 18 expression in SCC might be modulated by microenvironmental factors. 相似文献
68.
69.
70.
SM Dyer IS de la Lande DB Frewin & RJ Head 《Clinical and experimental pharmacology & physiology》1998,25(3-4):246-251
1. 5-Hydroxytryptamine (5-HT) exerts both contractile and relaxant effects in the marmoset isolated aorta, actions that are unaffected by the 5-HT2 antagonist ketanserin. The aim of the present study was to define the receptors mediating the contractile activity of 5-HT in the marmoset aorta.
2. Contractile responses were elicited in aortic rings that were either: (i) precontracted submaximally with the thromboxane A2 agonist U44069 in order to amplify the responses; or (ii) exposed to N ω -nitro- L -arginine (100 μmol/L) plus LY 53857 (0.1 μmol/L; a 5-HT2 receptor antagonist shown previously to inhibit relaxation). The effect of 5-HT on adenosine 3',5'-cyclic monophosphate (cAMP) formation was also investigated.
3. The effects of agonists and antagonists comprised: (i) agonist potencies in the order 5-carboxamidotryptamine > 5-HT > sumatriptan > 8-hydroxy-2-(di- n -propylamino)tetralin; (ii) inhibition of contractile action of 5-HT by the 5-HT1D antagonist GR 127935; (iii) a contractile response to methysergide; (iv) a lack of effect of tropisetron, an antagonist of 5-HT3 and 5-HT4 receptors; and (v) inhibition of forskolin-stimulated cAMP formation by 5-HT (in the presence of LY 53857), indicative of negative coupling to adenylate cyclase.
4. The above effects fulfil the criteria for a 5-HT1 -like receptor. In view of the previous finding that this contractile response is insensitive to ketanserin, it is concluded that the contractile effects of 5-HT in the marmoset aorta are mediated exclusively by a 5-HT1 -like receptor. 相似文献
2. Contractile responses were elicited in aortic rings that were either: (i) precontracted submaximally with the thromboxane A
3. The effects of agonists and antagonists comprised: (i) agonist potencies in the order 5-carboxamidotryptamine > 5-HT > sumatriptan > 8-hydroxy-2-(di- n -propylamino)tetralin; (ii) inhibition of contractile action of 5-HT by the 5-HT
4. The above effects fulfil the criteria for a 5-HT