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81.
The study aims to compare mechanical properties of polymer and metal honeycomb lattice structures between a computational model and an experiment. Specimens with regular honeycomb lattice structures made of Stratasys Vero PureWhite polymer were produced using PolyJet technology while identical specimens from stainless steel 316L and titanium alloy Ti6Al4V were produced by laser powder bed fusion. These structures were tested in tension at quasi-static rates of strain, and their effective Young’s modulus was determined. Analytical models and finite element models were used to predict effective Young’s modulus of the honeycomb structure from the properties of bulk materials. It was shown, that the stiffness of metal honeycomb lattice structure produced by laser powder bed fusion could be predicted with high accuracy by the finite element model. Analytical models slightly overestimate global stiffness but may be used as the first approximation. However, in the case of polymer material, both analytical and FEM modeling significantly overestimate material stiffness. The results indicate that computer modeling could be used with high accuracy to predict the mechanical properties of lattice structures produced from metal powder by laser melting. 相似文献
82.
Lubica Stuchlikova Beata Sciana Arpad Kosa Matej Matus Peter Benko Juraj Marek Martin Donoval Wojciech Dawidowski Damian Radziewicz Martin Weis 《Materials》2022,15(21)
Transient spectroscopies are sensitive to charge carriers released from trapping centres in semiconducting devices. Even though these spectroscopies are mostly applied to reveal defects causing states that are localised in the energy gap, these methods also sense-charge from quantum wells in heterostructures. However, proper evaluation of material response to external stimuli requires knowledge of material properties such as electron effective mass in complex structures. Here we propose a method for precise evaluation of effective mass in quantum well heterostructures. The infinite well model is successfully applied to the InGaAsN/GaAs quantum well structure and used to evaluate electron effective mass in the conduction and valence bands. The effective mass m/m0 of charges from the conduction band was 0.093 ± 0.006, while the charges from the conduction band exhibited an effective mass of 0.122 ± 0.018. 相似文献
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Objective On hospital admission, the morphology of the central pulmonary artery thromboemboli is an independent predictor of 30-day mortality in patients with massive pulmonary embolism (MPE). This may be due to the differential susceptibility of thromboemboli to thrombolysis. The aim of this study was to assess haemodynamic response to treatment in patients with MPE and morphologically different thromboemboli.Design Prospective observational study.Setting An 11-bed closed medical ICU at a 860-bed community general hospital.Patients Twelve consecutive patients with shock or hypotension due to MPE and central pulmonary thromboemboli detected by transesophageal echocardiography who were treated with thrombolysis between January 2000 through April 2002.Procedures Patients were divided into two groups according to the characteristics of detected central pulmonary thromboemboli: group 1, thrombi with one or more long, mobile parts; and group 2, immobile thrombi. Urokinase infusion was terminated when mixed venous oxygen saturation was stabilized above 60% for 15 min.Results At 2 h, the total pulmonary vascular resistance index was reduced more in group 1 than group 2 [from 27±12 mmHg/(l·min·m2) to 14±6 mmHg/(l·min·m2) (–52%) vs 27±8 mmHg/(l·min·m2) to 23±10 mmHg/(l·min·m2) (–15%), respectively, P=0.04]. In group 1 thrombolysis was terminated earlier than group 2 (89±40 min vs 210±62 min, respectively, P= 0.0024). The cumulative dose of urokinase used in group 1 was lower than group 2 (1.7±0.3 M i.u. vs 2.7±0.5 M i.u., respectively, P= 0.023).Conclusion Haemodynamic stabilization is achieved faster in patients with mobile central thromboemboli detected by transesophageal echocardiography during MPE. 相似文献
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Andreja Sinkovič Matej Vrbnjak Franci Svensek Simona Kirbis 《Central European Journal of Medicine》2013,8(5):591-596
In treatment of manic-depressive conditions long-term lithium therapy may be combined with an effective and relatively safe antidepressant venlafaxine. Combined overdose may increase the risk of early toxicity of both drugs and of delayed lithium intoxication, responding to symptomatic and renal replacement therapy. We present a patient with combined lithium and venlafaxine self-poisoning with nothing but delayed signs of lithium intoxication with the emphasis on early and late treatment. 41-year old woman attempted suicide by large amount of lithium and venlafaxine. On admission she was asymptomatic, but with increased serum lithium over 5mmol/L. After gastric lavage, active charcoal and laxative administration she was receiving IV fluids. After a delay of 63 hours she deteriorated acutely by disorientation, confusion, fasciculation and tremor and was readmitted to Intensive care unit. In spite serum lithium decreased to 2mmol/L clinical signs were attributed to delayed lithium intoxication. After symptomatic and renal replacement therapy the patient’s condition improved after few days. We conclude that decontamination procedures are effective in particular for venlafaxine poisoning. If increased serum lithium levels are noted renal replacement therapy may be started even in asymptomatic patients as delayed lithium intoxication is most likely after few days. 相似文献
88.
Karpanen T Bry M Ollila HM Seppänen-Laakso T Liimatta E Leskinen H Kivelä R Helkamaa T Merentie M Jeltsch M Paavonen K Andersson LC Mervaala E Hassinen IE Ylä-Herttuala S Oresic M Alitalo K 《Circulation research》2008,103(9):1018-1026
Vascular endothelial growth factor (VEGF)-B is poorly angiogenic but prominently expressed in metabolically highly active tissues, including the heart. We produced mice expressing a cardiac-specific VEGF-B transgene via the alpha-myosin heavy chain promoter. Surprisingly, the hearts of the VEGF-B transgenic mice showed concentric cardiac hypertrophy without significant changes in heart function. The cardiac hypertrophy was attributable to an increased size of the cardiomyocytes. Blood capillary size was increased, whereas the number of blood vessels per cell nucleus remained unchanged. Despite the cardiac hypertrophy, the transgenic mice had lower heart rate and blood pressure than their littermates, and they responded similarly to angiotensin II-induced hypertension, confirming that the hypertrophy does not compromise heart function. Interestingly, the isolated transgenic hearts had less cardiomyocyte damage after ischemia. Significantly increased ceramide and decreased triglyceride levels were found in the transgenic hearts. This was associated with structural changes and eventual lysis of mitochondria, resulting in accumulation of intracellular vacuoles in cardiomyocytes and increased death of the transgenic mice, apparently because of mitochondrial lipotoxicity in the heart. These results suggest that VEGF-B regulates lipid metabolism, an unexpected function for an angiogenic growth factor. 相似文献
89.
Background: In chronic heart failure (CHF) β-blockers reduce myocardial oxygen consumption and improve myocardial efficiency by shifting myocardial substrate utilization from increased free fatty acid oxidation to increased glucose oxidation. The effect of selective and nonselective β-blockers on total body resting energy production rate (EPR) and substrate utilization is not known. Methods: Twenty-six noncachectic patients with moderately severe heart failure (New York Heart Association class II or III, left ventricular ejection fraction < 0.40) were treated with carvedilol (37.5 ± 13.5 mg/12 h) or bisoprolol (5.4 ± 3.0 mg/d) for 6 months. Indirect calorimetry was performed before and after 6 months of treatment. Results: Resting EPR was decreased in carvedilol (5.021 ± 0.803 to 4.552 ± 0.615 kJ/min, P < .001) and bisoprolol group (5.230 ± 0.828 to 4.978 ± 0.640 kJ/min, P < .05; nonsignificant difference between groups). Lipid oxidation rate decreased in carvedilol and remained unchanged in bisoprolol group (2.4 ± 1.4 to 1.5 ± 0.9 mg m2/kg min versus 2.7 ± 1.1 to 2.5 ± 1.1 mg m2/kg min, P < .05). Glucose oxidation rate was increased only in carvedilol (2.6 ± 1.4 to 4.4 ± 1.6 mg m2/kg min, P < .05), but did not change in bisoprolol group. Conclusions: Both selective and nonselective β-blockers reduce total body resting EPR in noncachectic CHF patients. Carvedilol compared to bisoprolol shifts total body substrate utilization from lipid to glucose oxidation. 相似文献
90.
Ivana Dedinská Karol Graňák Matej Vnučák Petra Skálová Lea Kováčiková Ľudovít Laca Juraj Miklušica Dana Prídavková Peter Galajda Marián Mokáň 《Journal of diabetes and its complications》2019,33(4):315-322