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981.
R. Priori F. Conti F. L. Luan C. Arpino G. Valesini 《European journal of pediatrics》1994,153(5):344-346
We describe four Italian adolescents in whom a persistent, debilitating fatigue appeared after therapeutic ingestion of products containingl-tryptophan and subsequent to the development of a transient rise in eosinophil count and severe myalgia (Eosinophilia Myalgia Syndrome-EMS). Their clinical picture was indistinguishable from that of the socalled Chronic Fatigue Syndrome. A chronic fatigue may occur after diverse triggering agents and it represents the peculiar clinical evolution of these four paediatric cases of EMS. 相似文献
982.
M. A. N. Lodder A. de Haan A. J. Sargeant 《European journal of applied physiology》1994,69(5):429-434
The effect of growth on work output, energy consumption and efficiency during repetitive dynamic contractions was determined using extensor digitorum longus muscles of 40-, 60-, 120- and 700-day-old male Wistar rats. When work output of each contraction was normalized to the work output of the first contraction it was found that work output initially increased over the first 10–20 contractions by approximately 8% in each age group. Thereafter a faster decrease in work output was found in the youngest group (approximately 2% each contraction) compared to the older groups (approximately 0.7% each contraction). After 40 contractions the reduction in work output was significantly different only between the youngest group and the two oldest groups (–30% vs –5%). These differences in fatigue were not associated with differences in adenosine 5-triphosphate and phosphocreatine concentrations or in lactate production. Total work output and high-energy phosphate consumption increased by approximately 555% and 380% from age 40 to 120 days, respectively. Consequently, efficiency was significantly higher (approximately 32%) in the older groups compared to 40-day-old animals. Normalized for muscle mass, mean rate of high-energy phosphate consumption was similar in all groups whereas mean power output was significantly lower in the youngest group (approximately 46%). Thus, the difference in efficiency between the young and the other groups may be attributed to a lower external power production in the youngest group rather than changes in energy turnover. 相似文献
983.
Michael E. Mulligan M.D. 《Skeletal radiology》1995,24(3):201-203
The purpose of this report is to describe an early radiographic sign of stress fracture, the gray cortex. The imaging findings in three patients with tibial stress fractures were reviewed. The gray cortex sign was evident on the initial conventional radiographs in all three cases. It was prospectively reported as a sign of stress fracture in two patients and was evident on the initial radiographs (taken elsewhere) of the third patient, who was referred for additional workup of a possible neoplasm. Special imaging studies (technetium-99m bone scan, computed tomography, and magnetic resonance imaging) confirmed the diagnosis in all three cases. 相似文献
984.
Summary The presence of microdamage in the tibiae and femora of rats following repetitive loading in vivo was investigated by subjecting 48 male rats, aged 12 weeks, to treadmill running (26.8 m.min-1 on 10% grade) for 0.56 hours (5,000 cycles, E1), 1.13 hours, (10,000 cycles, E2), 2.27 hours (20,000 cycles, E3), and 3.4 hours (30,000 cycles, E4) with Group C as control. Following exercise, tibiae and femora were excised and the right limbs were tested in torsion at 180°.sec-1. Transverse sections were cut from the proximal, mid- and distal diaphysis of left tibiae and femora, bulk stained in basic fuchsin, cut to 50 m thick, and examined for the presence of microdamage. Following these periods of loading, tibiae and femora showed no evidence of microdamage initiation, as evidenced by light microscopy, or corresponding alterations in mechanical properties. It was concluded that the magnitude of loading produced by single bouts of intensive exercise, which encompassed up to 30,000 loading cycles, was insufficient to initiate fatigue microdamage in tibiae or femora of rats. 相似文献
985.
Objectives
To survey simple contact testing protocols for evaluating the mechanical integrity of zirconia dental ceramics. Specifically, to map vital material property variations and to quantify competing damage modes.Methods
Exploratory contact tests are conducted on layer structures representative of zirconia crowns on dentin.Results
Sharp-tip micro- and nano-indentations were used to investigate the roles of weak interfaces and residual stresses in veneered zirconia, and to map property variations in graded structures. Tests with blunt sphere indenters on flat specimens were used to identify and quantify various critical damage modes in simulated occlusal loading in veneered and monolithic zirconia.Significance
Contact testing is a powerful tool for elucidating the fracture and deformation modes that control the lifetimes of zirconia dental ceramics. The advocated tests are simple, and provide a sound physical basis for analyzing damage resistance of anatomically-correct crowns and other complex dental prostheses. 相似文献986.
Ana Maria Estivalete Marchionatti Vinícius Felipe Wandscher Iana Lamadrid Aurélio César Dalmolin Bergoli Liliana Gressler May 《Dental materials》2019,35(4):e63-e73
Objective
To compare file-splitting multilayer (fused and cemented) with monolithic Y-TZP on the fatigue flexural strength and finite element analysis (FEA) stresses. Additionally, to verify the effect of the material under tension in multilayer Y-TZP.Methods
Disc-shaped (diameter: 14.4 mm; thickness: 1.4 mm) monolithic Y-TZP (IPS e.max ZirCAD — Ivoclar Vivadent) and trilayer specimens with Y-TZP framework (IPS e.max ZirCAD), intermediate layer of fusion ceramic (IPS e.max CAD Crystall./Connect) or resin cement (Multilink Automix) and lithium disilicate veneer (IPS e.max CAD) were divided into five groups (n = 20): monolithic Y-TZP (M), fused file-splitting with framework under tension (F-FT), cemented file-splitting with framework under tension (C-FT), fused file-splitting with veneer under tension (F-VT) and cemented file-splitting with veneer under tension (C-VT). Fatigue flexural strength was determined (piston-on-three ball) by the staircase approach (750,000 cycles; 20 Hz). Mean and confidence intervals (CI) were calculated. FEA was evaluated under the application of the experimental mean fatigue load.Results
The fatigue strength was statistically different for all groups. Means and CI (MPa) were: M — 405.92 (CI 397.58–414.26), F-FT — 377.73 (CI 374.59–380.88), C-FT — 346.54 (CI 340.62–352.46), F-VT — 154.79 (CI 151.86–157.72) and C-VT — 100.34 (CI 97.42–103.26). FEA tensile stresses were similar to the mean experimental values (up to ?10 MPa of variation), with the most discrepant calculated stresses for C-FT (?20 MPa higher than experimental result).Significance
Monolithic specimens showed the highest flexural fatigue strength and fused file-splitting resulted in higher fatigue strength than cemented file-splitting. Groups with the framework under tension exhibited higher flexural fatigue strength. 相似文献987.
BACKGROUND: Fatigue is a common complaint in patients with sarcoidosis. We studied the effectiveness of dexmethylphenidate hydrochloride (d-MPH) in treating sarcoidosis-associated fatigue. METHODS: This was a double-blind, randomized, placebo-controlled, crossover trial of d-MPH. Patients were seen weekly and completed Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) and Fatigue Assessment Score (FAS) instruments. After a 1-week wash-in period, patients received either d-MPH or placebo. After 8 weeks, the medications were stopped. Following a 2-week wash-out period, patients were crossed over to 8 weeks of the other treatment. FVC and 6-min walk distance (6MWD) were determined initially and after each treatment arm. RESULTS: Ten patients with sarcoidosis were enrolled: 8 women and 5 African Americans. All were receiving systemic sarcoidosis therapy. Significant improvement in fatigue was reported by patients when receiving d-MPH (FACIT-F, p < 0.001; FAS, p < 0.02). FVC was higher at the end of 8 weeks of d-MPH compared to the baseline values (baseline median, 2.38 L; range, 1.17 to 4.53 L; placebo median, 2.41 L; range, 1.50 to 4.65 L; d-MPH median, 2.56 L; range, 1.50 to 4.96 L; p < 0.01). There was no significant difference in the 6MWD (baseline median, 330 m; range, 60 to 460 m; placebo median, 350 m; range, 180 to 460 m; d-MPH median, 390 m; range, 200 to 460 m). d-MPH was well tolerated. CONCLUSIONS: Treatment with d-MPH was associated with a significant improvement in sarcoidosis-associated fatigue. TRIAL REGISTRATION: Clinicaltrials.gov Identifier: NCT00361387. 相似文献
988.
989.
BackgroundSystemic lupus erythematosus (SLE) is a complex rheumatic autoimmune disease characterized by periods of exacerbations that can present damage in organs with important clinical manifestations. Objective: The aim of this study was to evaluate the effect of 12-week whole-body vibration exercise (WBVE) on the fatigue, functional ability and quality of life of women with systemic lupus erythematosus (SLE) in chronic glucocorticoids use (CGU). Methods: Twenty-one women were allocated randomly in the WBVE group or isometry group. The participants of WBVE group were positioned on the vibrating platform with 130° knee flexion and received the intervention twice a week for 12 weeks. The isometry group performed the same position and time, but without the stimulus of mechanical vibration. Fatigue, functional ability and the quality of life were evaluated at weeks 0, 6, and 12. Results: From a sample of seventy-seven individuals, seventeen participants completed the study, 8 in WBVE group and 9 in isometry group. Fatigue reduced in the WBVE group at 6 and 12 weeks of intervention (p = 0.04) and (p = 0.03) respectively. There was a significant improvement in the functional ability evaluated by the Health Assessment Questionnaire in the WBVE group compared to the isometry group (p = 0.03). Conclusion: WBVE would be a useful intervention for control of fatigue and improvement of the functional ability of women with SLE in CGU. 相似文献
990.
Irritable bowel syndrome (IBS) is a symptom-based disorder of gut-brain interactions generating abdominal pain. It is also associated with a vulnerability to develop extraintestinal symptoms, with fatigue often reported as one of the most disturbing. Fatigue is related to brain function and inflammation in several disorders, however, the mechanisms of such relations in IBS remain elusive. This study aimed to elucidate fatigue and its association with a resting state network of mesocorticolimbic regions of known importance in fatigue, and to explore the possible role of circulating TNF-α levels in IBS and healthy controls (HC). Resting state functional magnetic resonance imaging (fMRI) was conducted in 88 IBS patients and 47 HC of similar age and gender to investigate functional connectivity between mesocorticolimbic regions. Further, fatigue impact on daily life and plasma levels of the proinflammatory cytokine tumor necrosis factor-α (TNF-α), of known relevance to immune activation in IBS, were also measured. The selected mesocorticolimbic regions indeed formed a functionally connected network in all participants. The nucleus accumbens (NAc), in particular, exhibited functional connectivity to all other regions of interest. In IBS, fatigue impact on daily life was negatively correlated with the connectivity between NAc and dorsolateral prefrontal cortex bilaterally (left p = 0.019; right p = 0.038, corrected for multiple comparisons), while in HC, fatigue impact on daily life was positively correlated to the connectivity between the right NAc and anterior middle insula in both hemispheres (left p = 0.009; right p = 0.011). We found significantly higher levels of TNF-α in IBS patients compared to HC (p = 0.001) as well as a positive correlation between TNF-α and fatigue impact on daily life in IBS patients (rho = 0.25, p = 0.02) but not in HC (rho = −0.13, p = 0.37). There was no association between functional connectivity in the mesocorticolimbic network and plasma levels of TNF-α in either group In summary, this novel multimodal study provides the first evidence that the vulnerability to fatigue in IBS is associated with connectivity within a mesocorticolimbic network as well as immune activation. These findings warrant further investigation, both peripherally and potentially with measurements of central immune activation as well. 相似文献