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61.
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G M Barnas P J Mills C F Mackenzie M Ashby W L Sexton P C Imle P D Wilson 《The American review of respiratory disease》1991,143(2):240-244
We calculated respiratory system resistance (Rrs) and elastance (Ers) from pressure and flow at the mouth in six seated subjects relaxed at FRC (cheeks tightly compressed) during sinusoidal volume forcing (250, 500, and 750 ml) at 0.2, 0.4, and 0.6 Hz. Dependencies of Rrs and Ers on frequency and tidal volume were generally the same in each subject; Rrs tended to decrease with frequency and tidal volume, whereas Ers tended to increase with frequency and decrease with tidal volume. Multiple linear regression of combined data indicated that the frequency and tidal volume effects on Rrs and Ers were significant (p less than 0.05), and that the effects on Rrs decreased at higher flows. Average Rrs was highest (4.43 cm H2O/L/s +/- 0.21 SE) at 0.2 Hz-250 ml, and lowest (3.07 cm H2O/L/s +/- 0.37) at 0.6 Hz-750 ml. Average Ers was highest (12.1 cm H2O/L +/- 1.1) at 0.6 Hz-250 ml, and lowest (7.1 cm H2O/L +/- 0.6) at 0.2 Hz-750 ml. We conclude that frequency and tidal volume dependencies in Rrs and Ers in the normal range of breathing should be considered when interpreting measurements of respiratory system impedance or developing models to describe the mechanical behavior of the respiratory system. 相似文献
63.
P. M. Scholz M.D. G. J. Grover J. W. Mackenzie H. R. Weiss 《Basic research in cardiology》1990,85(6):575-584
Summary The aim of the present study was to determine if the relationship between myocardial O2 supply and O2 consumption was preserved after prolonged pressure overload due to aortic valve stenosis. This was examined in anesthetized open-chest dogs in which the aortic valve was plicated 6 months previously. We measured coronary blood flow with radioactive microspheres and regional small vessel O2 saturation with microspectrophotometry, to obtain O2 supply, and O2 consumption. Regional O2 consumption was calculated as the product of flow and O2 extraction. The left ventricular weight/body weight ratio was 81% greater in the dogs with aortic valve stenosis. There were no hemodynamic differences between the groups except that left ventricular systolic pressure was 38±22 mm Hg greater than aortic in the hypertrophied group. Coronary blood flow did not differ between the control and hypertrophied groups nor were there subepicardial vs subendocardial differences. When maximal coronary flow was determined with chromonar (10 mg/kg), the flow increase was significantly attenuated in the hypertrophied subendocardium (242.1±82.3 (hypertrophy) vs 512.4±204.1 ml·min–1·100 g–1 (control)). There were no significant differences in O2 extraction or O2 consumption/g between control and hypertrophied animals. There was a significantly lower O2 supply/consumption ratio in the subendocardium compared to the subepicardium of both groups. However, the O2 supply/consumption ratio was not decreased by hypertrophy. Thus, despite significant hypertrophy, a loss of flow reserve and a high left ventricular pressure, O2 supply/consumption balance is preserved in valvular aortic stenosis at rest. 相似文献
64.
Alya H. Bdaiwi Tanya Anne Mackenzie Lee Herrington Ian Horsley Ann M. Cools 《Journal of Athletic Training》2015,50(7):713-718
Context
Compromise to the acromiohumeral distance has been reported in participants with subacromial impingement syndrome compared with healthy participants. In clinical practice, patients with subacromial shoulder impingement are given strengthening programs targeting the lower trapezius (LT) and serratus anterior (SA) muscles to increase scapular posterior tilt and upward rotation. We are the first to use neuromuscular electrical stimulation to stimulate these muscle groups and evaluate how the muscle contraction affects the acromiohumeral distance.Objective
To investigate if electrical muscle stimulation of the LT and SA muscles, both separately and simultaneously, increases the acromiohumeral distance and to identify which muscle-group contraction or combination most influences the acromiohumeral distance.Design
Controlled laboratory study.Setting
Human performance laboratory.Patients or Other Participants
Twenty participants (10 men and 10 women, age = 26.9 ± 8.0 years, body mass index = 23.8) were screened.Intervention(s)
Neuromuscular electrical stimulation of the LT and SA.Main Outcome Measure(s)
Ultrasound measurement of the acromiohumeral distance.Results
Acromiohumeral distance increased during contraction via neuromuscular electrical stimulation of the LT muscle (t19 = −3.89, P = .004), SA muscle (t19 = −7.67, P = .001), and combined LT and SA muscles (t19 = −5.09, P = .001). We observed no differences in the increased acromiohumeral distance among the 3 procedures (F2,57 = 3.109, P = .08).Conclusions
Our results supported the hypothesis that the muscle force couple around the scapula is important in rehabilitation and scapular control and influences acromiohumeral distance.Key Words: subacromial impingement syndrome, real-time ultrasound, rehabilitationKey Points
- Acromiohumeral distance increased during neuromuscular electrical stimulation of the lower trapezius muscle, serratus anterior muscle, and combined lower trapezius and serratus anterior muscles.
- The increase in acromiohumeral distance was not different among the 3 neuromuscular electrical-stimulation procedures.
- The muscle force couple around the scapula is important in rehabilitation and scapular control and influences acromiohumeral distance.
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Escherichia coli virulence and renal scarring 总被引:1,自引:0,他引:1
N Topley R K Mackenzie R Steadman J D Williams 《The Journal of infectious diseases》1989,160(6):1081-1083
69.
R. El-Gabalawy C.S. Mackenzie M.A. Thibodeau G.J.G. Asmundson J. Sareen 《Clinical psychology review》2013
Health anxiety disorders (e.g., hypochondriasis) are prevalent but understudied in older adults. Existing research suggests that severe health anxiety has a late age of onset, perhaps because of comorbidity with physical health conditions that are more likely to occur with aging. Despite being under diagnosed in later life due to a lack of age-appropriate diagnostic criteria, significant positive associations with age suggest that health anxiety disorders are more prevalent in older than younger adults. Preliminary research also highlights the complexity of these disorders in older adults and the potential importance of medical morbidity as a risk factor. This review explores the complexities of health anxiety disorders in later life with a focus on understanding defining features, prevalence rates, correlates, assessment, diagnosis, and treatment. We offer a theoretical model of the development of severe health anxiety among older adults to encourage further research on this important and under-studied topic. 相似文献
70.
Thomas A. Ravenscroft Matt C. Baker Nicola J. Rutherford Manuela Neumann Ian R. Mackenzie Keith A. Josephs Bradley F. Boeve Ronald Petersen Glenda M. Halliday Jillian Kril John C. van Swieten William W. Seeley Dennis W. Dickson Rosa Rademakers 《Neurobiology of aging》2013
The nuclear protein fused in sarcoma (FUS) is found in cytoplasmic inclusions in a subset of patients with the neurodegenerative disorder frontotemporal lobar degeneration (FTLD-FUS). FUS contains a methylated arginine–glycine–glycine domain that is required for transport into the nucleus. Recent findings have shown that this domain is hypomethylated in patients with FTLD-FUS. To determine whether the cause of hypomethylation is the result of mutations in protein N-arginine methyltransferases (PRMTs), we selected 3 candidate genes (PRMT1, PRMT3, and PRMT8) and performed complete sequencing analysis and real-time polymerase chain reaction mRNA expression analysis in 20 FTLD-FUS cases. No mutations or statistically significant changes in expression were observed in our patient samples, suggesting that defects in PRMTs are not the cause of FTLD-FUS. 相似文献