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排序方式: 共有247条查询结果,搜索用时 328 毫秒
1.
Nicolelis MA Ghazanfar AA Stambaugh CR Oliveira LM Laubach M Chapin JK Nelson RJ Kaas JH 《Nature neuroscience》1998,1(7):621-630
We used simultaneous multi-site neural ensemble recordings to investigate the representation of tactile information in three areas of the primate somatosensory cortex (areas 3b, SII and 2). Small neural ensembles (30-40 neurons) of broadly tuned somatosensory neurons were able to identify correctly the location of a single tactile stimulus on a single trial, almost simultaneously. Furthermore, each of these cortical areas could use different combinations of encoding strategies, such as mean firing rate (areas 3b and 2) or temporal patterns of ensemble firing (area SII), to represent the location of a tactile stimulus. Based on these results, we propose that ensembles of broadly tuned neurons, located in three distinct areas of the primate somatosensory cortex, obtain information about the location of a tactile stimulus almost concurrently. 相似文献
2.
The minute ventilation (VE) and carbon dioxide output (VCO&sub2;) adaptations to 12 weeks of cardiac rehabilitation were investigated in diagnosis-matched elderly patients (ELD) and younger patients (YNG). Thirty ELD (25 males, 5 females; age equals 69.2?+/-3.9 years) and 30 YNG (27 males, 3 females; age equals 48.3?+/-7.0 years) were exercise tested at program entry (T1) and completion (T2). Peak oxygen uptake (VO&sub2; peak) and ventilatory threshold (VT) (ml kg-1 min-1) were greater for YNG at both T1 and T2 (p is less than 0.01). Both ELD and YNG showed significant T1 to T2 improvements (p is less than 0.01) for VO&sub2; peak (21.1% and 23.4%) and VT (20.1% and 12.4%). The VE/VCO&sub2; ratio was greater (p is less than 0.01) for ELD but approached YNG values after training. The VCO&sub2;/VO&sub2; slope showed a greater T1 to T2 reduction in ELD (12.4% vs 3.4%). There was no relationship (r(2) equals 0.15; NS) between the percentage change in VO&sub2; peak and VE/VCO&sub2; indicating unrelated mechanisms of improvement. We conclude that ELD showed similar improvements in VO&sub2; peak but greater improvements in their ventilatory tolerance for submaximal exercise. These changes indicate improvements in aging-enhanced exercise ventilation, are important for performance of normal activities of daily living, and would have been undetectable without gas exchange analysis. 相似文献
3.
4.
Scott Yeudall Norbert Leitinger Victor E. Laubach 《American journal of transplantation》2020,20(3):633-640
The role of extracellular purine nucleotides, including adenosine triphosphate (ATP) and adenosine, as modulators of posttransplantation outcome and ischemia‐reperfusion injury is becoming increasingly evident. Upon pathological release of ATP, binding and activation of P2 purinergic surface receptors promote tissue injury and inflammation, while the expression and activation of P1 receptors for adenosine have been shown to attenuate inflammation and limit ischemia‐induced damage, which are central to the viability and long‐term success of allografts. Here we review the current state of the transplant field with respect to the role of extracellular nucleotide signaling, with a focus on the sources and functions of extracellular ATP. The connection between ischemia reperfusion, purinergic signaling, and graft preservation, as well as the role of ATP and adenosine as driving factors in the promotion and suppression of posttransplant inflammation and allograft rejection, are discussed. We also examine novel therapeutic approaches that take advantage of the ischemia‐reperfusion‐responsive and immunomodulatory roles for purinergic signaling with the goal of enhancing graft viability, attenuating posttransplant inflammation, and minimizing complications including rejection, graft failure, and associated comorbidities. 相似文献
5.
Lung transplant reperfusion injury involves pulmonary macrophages and circulating leukocytes in a biphasic response 总被引:5,自引:0,他引:5
Fiser SM Tribble CG Long SM Kaza AK Cope JT Laubach VE Kern JA Kron IL 《The Journal of thoracic and cardiovascular surgery》2001,121(6):1069-1075
OBJECTIVE: Both donor pulmonary macrophages and recipient circulating leukocytes may be involved in reperfusion injury after lung transplantation. By using the macrophage inhibitor gadolinium chloride and leukocyte filters, we attempted to identify the roles of these two populations of cells in lung transplant reperfusion injury. METHODS: With our isolated, ventilated, blood-perfused rabbit lung model, all groups underwent lung harvest followed by 18-hour cold storage and 2-hour blood reperfusion. Measurements of pulmonary artery pressure, lung compliance, and arterial oxygenation were obtained. Group I (n = 8) served as a control. Group II (n = 8) received gadolinium chloride at 14 mg/kg 24 hours before lung harvest. Group III (n = 8) received leukocyte-depleted blood reperfusion by means of a leukocyte filter. RESULTS: The gadolinium chloride group had significantly improved arterial oxygenation and pulmonary artery pressure measurements compared with control subjects and an improved arterial oxygenation compared with the filter group after 30 minutes of reperfusion. After 120 minutes of reperfusion, however, the filter group had significantly improved arterial oxygenation and pulmonary artery pressure measurements compared with the control group and an improved arterial oxygenation compared with the gadolinium chloride group. CONCLUSIONS: Lung transplant reperfusion injury occurs in two phases. The early phase is mediated by donor pulmonary macrophages and is followed by a late injury induced by recipient circulating leukocytes. 相似文献
6.
Kaza AK Kron IL Kern JA Long SM Fiser SM Nguyen RP Tribble CG Laubach VE 《The Annals of thoracic surgery》2001,71(5):1645-1650
BACKGROUND: We sought to identify the role of retinoic acid (RA) upon lung growth. RA has a role in perinatal lung development, and we hypothesized that exogenous RA would enhance postpneumonectomy compensatory lung growth. METHODS: Utilizing the postpneumonectomy rat model, we studied the impact of RA upon contralateral lung growth. Adult Sprague-Dawley rats were divided into three groups. Group S underwent a sham left thoracotomy, group P underwent left pneumonectomy, and group R underwent left pneumonectomy with administration of exogenous RA (0.5 microg/g/day intraperitoneally). We then quantitated right lung growth after 10 and 21 days. Lung weight and volume were expressed as a ratio to the final body weight (lung weight and volume indices, LWI and LVI). Epidermal growth factor receptor (EGFR) expression was quantitated using Western blot analysis. Cellular proliferation index (CPI) was determined using BrdU immunostaining. RESULTS: LWI, LVI, CPI, and EGFR expression at 21 days were significantly higher in group R versus S and P. At the 10-day interval, both LWI and LVI were significantly higher in group R versus S and P. CONCLUSIONS: RA administration markedly enhances lung growth after pneumonectomy, as evidenced by increases in LWI, LVI, and CPI. Upregulation of EGFR expression was associated with these effects. 相似文献
7.
Boyle WA Parvathaneni LS Bourlier V Sauter C Laubach VE Cobb JP 《Circulation research》2000,87(7):E18-E24
Septic shock is characterized by vasodilation and decreased responsiveness to vasoconstrictors. Recent studies suggest this results from nitric oxide (NO) overproduction after expression of the calcium-independent isoform of NO synthase (iNOS) in smooth muscle cells. However, direct evidence linking iNOS (NOS2) expression and decreased microvascular responsiveness after septic stimuli is lacking. In the present study, we determined the effect of bacterial lipopolysaccharide (LPS, 20 mg/kg, IP) on smooth muscle contraction and endothelial relaxation in mesenteric resistance arteries from wild-type and iNOS knockout mice. Four hours after challenge with LPS or saline in vivo, concentration-dependent responses to norepinephrine (NE) and acetylcholine (NE+ACh) were measured in cannulated, pressurized vessels ex vivo. In vessels from wild-type mice, NE-induced contraction was markedly impaired after LPS, and pretreatment with the iNOS inhibitor aminoguanidine (AG) partly restored the NE contraction. In contrast, NE contraction in microvessels from iNOS knockout mice was unaffected by LPS. ACh-induced relaxation was unaffected by LPS in vessels from either genotype. These data provide direct evidence that iNOS gene expression mediates the LPS-induced decrease in microvascular responsiveness to vasoconstrictors. Moreover, the observation that AG did not fully restore NE contraction after LPS, whereas iNOS gene deficiency did, suggests that iNOS expression plays a central role in the development of the NO-independent effect of LPS on microvascular responsiveness. Finally, our data indicate that LPS or iNOS expression has little effect on endothelium-dependent relaxation, and eNOS activity does not appear to play a role in the decreased smooth muscle responsiveness after LPS in this model. The full text of this article is available at http://www.circresaha.org. 相似文献
8.
9.
Laubach M 《Journal of neuroscience methods》2004,134(2):159-168
Investigations of neural coding in many brain systems have focused on the role of spike rate and timing as two means of encoding information within a spike train. Recently, statistical pattern recognition methods, such as linear discriminant analysis (LDA), have emerged as a standard approach for examining neural codes. These methods work well when data sets are over-determined (i.e., there are more observations than predictor variables). But this is not always the case in many experimental data sets. One way to reduce the number of predictor variables is to preprocess data prior to classification. Here, a wavelet-based method is described for preprocessing spike trains. The method is based on the discriminant pursuit (DP) algorithm of Buckheit and Donoho [Proc. SPIE 2569 (1995) 540-51]. DP extracts a reduced set of features that are well localized in the time and frequency domains and that can be subsequently analyzed with statistical classifiers. DP is illustrated using neuronal spike trains recorded in the motor cortex of an awake, behaving rat [Laubach et al. Nature 405 (2000) 567-71]. In addition, simulated spike trains that differed only in the timing of spikes are used to show that DP outperforms another method for preprocessing spike trains, principal component analysis (PCA) [Richmond and Optican J. Neurophysiol. 57 (1987) 147-61]. 相似文献
10.
Timothy R. McConnell PhD ; Charles A. Laubach Jr. MD; Mumtaz Memon MD ; Jacqueline K. Gardner MS ; Troy A. Klinger MS ; Rebecca J. Palm MS 《The American journal of geriatric cardiology》2000,9(4):210-218
Does 12 weeks of cardiac rehabilitation improve quality of life and self efficacy in patients >70 years of age following an acute myocardial infraction or bypass surgery? Three hundred forty four patients were divided into an Older group (70–89 years of age; n=122) and a younger group (50–69 years of age; n=222). Two hundred fifteen had bypass surgery (Surgical group) and 129 had a myocardial infarction (MI group). Quality of life emotions domain was greater for the Older group at week 12 ( p =0.066). The Surgical group had greater increases in overall quality of life and quality of life limitations domain ( p =0.012; p <0.001). Self efficacy scores were greater for the Younger group. MI group had greater self efficacy at week 1, while the Surgical group was greater at week 12 ( p <0.001). These results suggest age and diagnosis related differences in quality of life and self efficacy. 相似文献