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901.
Cytotoxicity of glutaraldehyde crosslinked collagen/poly(vinyl alcohol) films is by the mechanism of apoptosis 总被引:5,自引:0,他引:5
Collagen has been investigated as a potential natural biomaterial, because of its occurrence in the extracellular matrix. Collagen requires crosslinking in this context, by reagents that are often cytotoxic. Glutaraldehyde is one such agent that is potentially cytotoxic. The aim of this study was to determine the cause of poor cell attachment and growth on collagen/poly(vinyl alcohol) bioartificial composite films, when crosslinked with glutaraldehyde. Dehydrothermal crosslinking was used as a comparison. Human osteoblasts were observed to undergo apoptosis on glutaraldehyde crosslinked films dependent on concentration of collagen present. Higher collagen content resulted in higher levels of apoptosis with poor cell attachment and spreading of remaining cells. Post-treatment of films with 8% L-glutamic acid prevented the apoptotic response of osteoblasts and allowed attachment and spreading. The addition of 100 nM insulin-like growth factor-1 to the culture medium also prevented apoptosis. Glutaraldehyde toxicity of crosslinked collagen has been demonstrated in this study, the mechanism of which is apoptosis. This study indicates that poor biocompatibility and induction of apoptosis on collagen/poly(vinyl alcohol) films crosslinked by glutaraldehyde are attributed to glutaraldehyde components on the surface of the films (not residual glutaraldehyde), whose effects can be quenched by glutamic acid, and prevented by insulin-like growth factor-1. 相似文献
902.
903.
This study describes the physicochemical properties and in vitro resistance to encrustation of solvent cast films composed of either poly(epsilon-caprolactone) (PCL), prepared using different ratios of high (50,000) to low (4000) (molecular weight) m.wt., or blends of PCL and the polymeric antimicrobial complex, poly(vinylpyrrolidone)-iodine (PVP-I). The incorporation of PVP-I offered antimicrobial activity to the biomaterials. Films were characterised in terms of mechanical (tensile analysis, dynamic mechanical thermal analysis) and surface properties (dynamic contact angle analysis, scanning electron microscopy), whereas degradation (at 37 degrees C in PBS at pH 7.4) was determined gravimetrically. The resistance of the films to encrustation was evaluated using an in vitro encrustation model. Reductions in the ratio of high:low-m.wt. PCL significantly reduced the ultimate tensile strength, % elongation at break and the advancing contact angle of the films. These effects were attributed to alterations in the amorphous content and the more hydrophilic nature of the films. Conversely, there were no alterations in Young's modulus, the viscoelastic properties and glass-transition temperature. Incorporation of PVP-I did not affect the mechanical or rheological properties of the films, indicative of a limited interaction between the two polymers in the solid state. Manipulation of the high:low m.wt. ratio of PCL significantly altered the degradation of the films, most notably following longer immersion periods, and resistance to encrustation. Accordingly, maximum degradation and resistance to encrustation was observed with the biomaterial composed of 40:60 high:low m.wt. ratios of PCL; however, the mechanical properties of this system were considered inappropriate for clinical application. Films composed of either 50:50 or 60:40 ratio of high:low m.wt. PCL offered an appropriate compromise between physicochemical properties and resistance to encrustation. This study has highlighted the important usefulness of degradable polymer systems as ureteral biomaterials. 相似文献
904.
Parent visual analogue scale ratings of children's pain do not reliably reflect pain reported by child 总被引:2,自引:0,他引:2
OBJECTIVES: To determine whether parent and child visual analogue scale (VAS) scores for the pain associated with acute conditions in the child agree sufficiently for these methods of measurement to be considered interchangeable in pain and analgesia research. DESIGN: This was a prospective, two-group, repeated measures, blinded study in an urban pediatric emergency department. Children aged 8 to 15 years seeking treatment for painful conditions and the parents of these children were asked to rate the child's pain independently using a VAS on as many as four occasions at 20-minute intervals. Both participants were blinded to their previous rating and the rating of the other participant. The main outcome measure was the correlation of child and parent VAS pain scores by Pearson correlation and bias plot (Bland-Altman) analysis of agreement between tests. RESULTS: Seventy-eight child-parent sets participated, yielding 289 VAS pain score comparison pairs for evaluation. The correlation between child and parent VAS pain scores was 0.63 (95% CI, 0.56-0.70). Bias plot analysis revealed a bias of 5% and 95% limits of agreement from -38 to +47 mm. The degree of difference between child and parent scores was variable, but there was an increasing tendency for parents to underestimate the child's pain when the child recorded VAS pain scores at the higher end of the scale. CONCLUSIONS: Parents' VAS score ratings of their children's pain correlate only moderately with the children's VAS pain scores and show poor levels of agreement. The difference between the measures is variable and appears to be more marked when the child reports a higher VAS score. This research raises doubt about whether parental rating of a child's pain is an appropriate surrogate marker in pediatric pain and analgesia research. 相似文献
905.
Predictors of 30-month outcome after perinatal depression: role of proton MRS and socioeconomic factors 总被引:1,自引:0,他引:1
Miller SP Newton N Ferriero DM Partridge JC Glidden DV Barnwell A Chuang NA Vigneron DB Barkovich AJ 《Pediatric research》2002,52(1):71-77
The objective was to determine in infants with perinatal depression whether the relative concentrations of N-acetylaspartate and lactate in the neonatal period are associated with (1) neurodevelopmental outcome at 30 mo of age or (2) deterioration in outcome from age 12 to 30 mo; and to determine whether socioeconomic factors are associated with deterioration in outcome. Thirty-seven term neonates were prospectively studied with single-voxel proton magnetic resonance spectroscopy of the basal nuclei and intervascular boundary zones. Thirty-month outcomes were classified as normal [if Mental Development Index of the Bayley Scales of Infant Development (MDI) >85 and neuromotor scores (NMS) <3; n = 15], abnormal [if MDI or=3 at 12 and 30 mo; n = 11], or deteriorated [if normal at 12 mo and abnormal at 30 mo (MDI or=3); n = 11]. Thirty percent (11/37) of our cohort deteriorated between 12 and 30 mo. N-acetylaspartate/choline decreased across the groups ordered as normal, deteriorated, and abnormal [in basal nuclei (p 相似文献
906.
907.
908.
Disler P Hansford A Skelton J Wright P Kerr J O'Reilly J Hepworth J Middleton S Sullivan C 《American journal of physical medicine & rehabilitation / Association of Academic Physiatrists》2002,81(8):622-625
Obstructive sleep apnea can be diagnosed in approximately 60% of stroke survivors in the postacute period and has been found to be associated with increased mortality and a worse functional outcome at 3 and 12 mo after discharge. In this study, 38 patients undergoing rehabilitation after stroke underwent sleep studies by using the AutoSet Portable II Plus device; obstructive sleep apnea was found in 18 of the patients, and five consecutively diagnosed patients were treated on the ward with nasal continuous positive airway pressure. The research has shown that it is feasible to routinely implement a diagnostic and therapeutic approach to sleep apnea on the rehabilitation ward, which is hoped to have a positive influence on mortality, functional outcome, and secondary prevention. 相似文献
909.
910.