全文获取类型
收费全文 | 1029792篇 |
免费 | 68006篇 |
国内免费 | 2697篇 |
专业分类
耳鼻咽喉 | 14491篇 |
儿科学 | 32513篇 |
妇产科学 | 29110篇 |
基础医学 | 144040篇 |
口腔科学 | 30289篇 |
临床医学 | 82980篇 |
内科学 | 214179篇 |
皮肤病学 | 23179篇 |
神经病学 | 81924篇 |
特种医学 | 39340篇 |
外国民族医学 | 338篇 |
外科学 | 157548篇 |
综合类 | 19763篇 |
一般理论 | 286篇 |
预防医学 | 77490篇 |
眼科学 | 23158篇 |
药学 | 72922篇 |
中国医学 | 2477篇 |
肿瘤学 | 54468篇 |
出版年
2021年 | 9088篇 |
2019年 | 9694篇 |
2018年 | 14287篇 |
2017年 | 10219篇 |
2016年 | 10639篇 |
2015年 | 12011篇 |
2014年 | 16375篇 |
2013年 | 24943篇 |
2012年 | 35371篇 |
2011年 | 37635篇 |
2010年 | 21878篇 |
2009年 | 19668篇 |
2008年 | 34180篇 |
2007年 | 36243篇 |
2006年 | 35662篇 |
2005年 | 34990篇 |
2004年 | 33057篇 |
2003年 | 31605篇 |
2002年 | 30889篇 |
2001年 | 44491篇 |
2000年 | 46079篇 |
1999年 | 38893篇 |
1998年 | 10493篇 |
1997年 | 9489篇 |
1996年 | 9401篇 |
1995年 | 8693篇 |
1994年 | 8291篇 |
1992年 | 29250篇 |
1991年 | 27877篇 |
1990年 | 27255篇 |
1989年 | 26029篇 |
1988年 | 24171篇 |
1987年 | 23732篇 |
1986年 | 22803篇 |
1985年 | 21624篇 |
1984年 | 16174篇 |
1983年 | 13780篇 |
1982年 | 8226篇 |
1979年 | 14917篇 |
1978年 | 10419篇 |
1977年 | 8802篇 |
1976年 | 8333篇 |
1975年 | 9199篇 |
1974年 | 10982篇 |
1973年 | 10512篇 |
1972年 | 9924篇 |
1971年 | 9215篇 |
1970年 | 8851篇 |
1969年 | 8307篇 |
1968年 | 7941篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
J. Belchi-Hernandez S. Moreno-Grau F. Sánchez-Gascón J. Bayo B. Elvira Rendueles B. Bartolomé J. M. Moreno J. Martinez Quesada R. Palacios Peláez 《Allergy》1998,53(3):241-248
Zygophyllum fahago is a herbaceous plant found widely in the Mediterranean area. There are no previous reports of its allergenicity. An aerobiologic and clinical survey was conducted in Murcia, southern Spain, to determine the quantity of airborne pollen and establish the possible role of this pollen as a cause of allergic symptoms. With a Hirst volumetric trap, we determined the atmospheric concentrations of this pollen in 1993, 1994,1995, and 1996. Of 1180 patients tested, 181 (15,34%) had a positive skin test. To determine its allergenicity, we divided 47 patients into three groups: in group 1, all the patients had symptoms of rhinoconjunctivitis plus asthma; in groups 2 and 3, rhinoconjunctivitis. In group 1, we performed a bronchial provocation test (BPT): in groups 2 and 3, we performed nasal provocation (NPT) and conjunctival provocation (CPT) tests, respectively, SDS-PAGE was used to characterize the antigenic fractions and RAST inhibition to determine cross-reactivity with other pollens. The pollen dispersion period is from May to September (445 grains/m3 ), BPT was positive in 13 of 15 patients, NPT in 14 of 16 patients, and CPT in 13 of 16 patients. RAST inhibition revealed cross-reactivity with Mercurialis, Ricinus, Olea. and Betula. SDS-PAGE identified 25 IgE antibody-binding components, five of which (60, 65, 41, 38, and 15.5/14,7 kDa) were recognized by 40% of the sera. By SDS-PAGE immunoblotting with sunflower antiprofilin rabbit serum and affinity chromatography we established that the Z. fahago extract has profilin. This study shows that this pollen becomes airborne and elicits an IgE response which triggers respiratory symptoms in allergic subjects. 相似文献
992.
993.
994.
The present study was designed to examine the effects of a >30kDa fraction of medium conditioned for 2 days by adult rat seminiferoustubules on inhibin secretion by cultured tubules, and on spermatogenesisand fertility of male rats. Inhibin secretion was assayed byadding the >30 kDa fraction to 5 cm segments of adult ratseminiferous tubules and measuring inhibin by radioimmunoassayat 2 day intervals. Fertility was assayed by injecting malerats daily for up to 45 days with the >30 kDa fraction andthen mating them with a proestrus female, or by injecting for15 days and mating them with two female rats. The assay usedto evaluate the in-vivo effect of the >30 kDa fraction onthe testis involved an assessment of frequencies of seminiferoustubule stages scored by transillumination on intact tubules.The addition of the >30 kDa fraction to the adult rat seminiferoustubules cultured for 2 days resulted in an inhibition of inhibinsecretion into the medium. This effect was reversed when thefraction was removed and changed with fresh medium and culturedfor a further 4 days. The >30 kDa fraction administered i.p.to adult male rats resulted in a low fertilization rate comparedto control rats (67%) (P < 0.05). The assessment of frequenciesof seminiferous tubule stages scored by transillumination showedan increased frequency of stage VI and decreased frequency ofstages VII and VIII after treatment. The results of the presentstudy provide additional evidence that local regulation of Sertolicell function is mediated by a >30 kDa component or componentssecreted by adult seminiferous tubules which could arrest spermatogenesis. 相似文献
995.
996.
Expression of CD35 (CR1) and CD11b (CR3) on circulating neutrophils and eosinophils from allergic asthmatic children 总被引:3,自引:0,他引:3
C. BERENDS M. O. HOEKSTRA B. DIJKHUIZEN J. G. R. DE MONCHY J. GERRITSEN H. F. KAUFFMAN 《Clinical and experimental allergy》1993,23(11):926-933
Complement receptors on neutrophils and eosinophils play a role in activation and adhesion. During asthmatic reactions these receptors have been found elevated on circulating granulocytes. In the present study we compared the expression of CD35 (complement receptor type 1) and CD11b (complement receptor type 3) on neutrophils and eosinophils from asthmatic and non-asthmatic children. This was done in whole blood samples using depolarized light scattering for the discrimination of neutrophils and eosinophils. The non-stimulated expression as well as the upregulated expression of receptors by the chemotactic peptide N-formylmethionyl-leucyl-phenyl-alanine (fMLP) were studied. The results showed that without prior stimulation only the expression of CD35 on neutrophils was significantly elevated in children with asthma (P<0.05). After up-regulation with fMLP, the CD11b expression on neutrophils (P<0.005, fMLP: 0.002 microM) and eosinophils (P<0.05, fMLP: 0.02 microM) was significantly higher in asthmatic children than in the controls. These results indicate that the inducible expression of CD11b on neutrophils and eosinophils from allergic asthmatic children is primed in vivo. 相似文献
997.
C. Caramella F. Ferrari M. C. Bonferoni M. E. Sangalli M. De Bernardi Di Valserra F. Feletti M. R. Galmozzi 《Biopharmaceutics & drug disposition》1993,14(2):143-160
Six preparations were considered: three multiple unit dosage forms (micropellets in capsules) (D, E and G) and one matrix tablet (B) were experimental prolonged release formulations, two non-disintegrating tablets (A and C) were commercial products. The in vitro dissolution behaviour of the differing formulations was investigated using the USP XXII paddle apparatus. The in vivo study was effected on a panel of 12 healthy volunteers. The two commercial tablets (A and C) showed mean dissolution time (MDT) of 1.34 and 1.44 h and td of 91 and 92 min, respectively; for prolonged release formulations (B, E, D, and G) MDT ranged between 2.28 and 4.23 h and td between 149 and 291 min. The mean residence time (MRT) was 8.68 and 6.47 h for tablets A and C, respectively; it ranged between 9.62 and 10.24 h for the multiple unit formulations E, D, and G and was 11.27 h for matrix B. Formulation B also showed the higher apparent elimination half-life t1/2 (7.12 h), while apparent t1/2 for all the other formulations were very similar, ranging between 5.04 and 5.28 h. High variability between the various formulations was found for Cmax and AUC values, and no relationships could be established with the type of formulation. An in vitro/in vivo correlation was found for all the formulations examined on the basis of analogous parameters (MDT and MRT); (r = 0.83, p <0.05). In a few cases the Wagner-Nelson deconvolution method was applied to individual plasma level versus time curves and the corresponding absorption curves were obtained. In these cases the in vitro/in vivo correlation was tested on the basis of the comparison of the in vivo absorption curves with the in vitro dissolution profiles. This was accomplished using the ‘Levy's plot’ (per cent released versus per cent absorbed) approach and provided further support for the correlation found. 相似文献
998.
999.
Summary Physeal distraction was applied with an external fixator to the triradiate cartilage of dogs with the aim of increasing the capacity of the acetabulum. The force was continued for from 2 to 6 weeks and the consequent changes were evaluated with regard to function and structure by radiography and microscopy. The distraction, without producing epiphysiolysis and destruction of the cartilage, resulted in expansion of the pelvic bones. The depth and volume of the acetabulum were increased, but the acetabular angle was decreased. Distraction also caused proliferation of the lacunar cells and the number of mammillary processes in the cartilage columns increased. Distraction can therefore be applied to the triradiate cartilage to enlarge the capacity of the acetabulum without producing epiphysiolysis.
Résumé Dans cette étude une distraction a été appliquée sur le cartilage en Y. Douze chiens bâtards, âgés de 2.5 à 4 mois, ont été utilisés pour cette expérimentation. Une force de distraction de 80 Newton a été appliquée d'emblée sur le cartilage en Y. L'application de cette force a été poursuivie sur les animaux pendant 2, 4 ou 6 semaines. A la fin de cette période, les changements de la cavité cotyloïde et du cartilage en Y ont été évalués sur le plan fonctionnel, morphologique, radiologique et histopathologique Aucune altération fonctionnelle n'a été mise en évidence dans les groupes opérés par rapport au groupe de contrôle. On a observé que la distraction a déterminé une expansion massive de l'ilion, du pubis et de l'ischion. Sur les hanches de contrôle la profondeur de la cavité cotyloïde a été évaluée à 13.5 mm, le volume à 1.96 cc et l'angle de la cavité cotyloïde à 29.9°. Après distraction ces valeurs ont été respectivement de 14.4 mm, de 2.10 cc et de 25.7°. La distraction entraîne donc un accroissement de profondeur et de volume de la cavité cotyloïde, mais inversement une diminution de l'angle de cette cavité. Ces résultats montrent que la distraction détermine une prolifération des cellules lacunaires et un accroissement des processus mammaires dans les colonnes du cartilage en Y. Ils montrent également qu'elle peut augmenter la taille de l'acetabulum.相似文献
1000.
Ch. Deliveliotis F. Sofras D. Picramenos Ch. Bellos N. J. Stavropoulos Th. Becopoulos 《International urology and nephrology》1995,27(4):365-367
We present a very rare case of gigantic hydrocalycosis which was caused by an obstructed stone. It was so large that it displaced
the rest kidney into the contralateral lumbar fossa giving the appearance of a crossed ectopic kidney. 相似文献