全文获取类型
收费全文 | 61752篇 |
免费 | 2826篇 |
国内免费 | 410篇 |
专业分类
耳鼻咽喉 | 865篇 |
儿科学 | 1510篇 |
妇产科学 | 1603篇 |
基础医学 | 7351篇 |
口腔科学 | 2142篇 |
临床医学 | 4392篇 |
内科学 | 17034篇 |
皮肤病学 | 1588篇 |
神经病学 | 5052篇 |
特种医学 | 1588篇 |
外科学 | 9238篇 |
综合类 | 279篇 |
一般理论 | 14篇 |
预防医学 | 3903篇 |
眼科学 | 1064篇 |
药学 | 3314篇 |
中国医学 | 192篇 |
肿瘤学 | 3859篇 |
出版年
2024年 | 44篇 |
2023年 | 394篇 |
2022年 | 819篇 |
2021年 | 1761篇 |
2020年 | 943篇 |
2019年 | 1486篇 |
2018年 | 2193篇 |
2017年 | 1376篇 |
2016年 | 1432篇 |
2015年 | 1640篇 |
2014年 | 2178篇 |
2013年 | 2971篇 |
2012年 | 4656篇 |
2011年 | 4753篇 |
2010年 | 2595篇 |
2009年 | 2201篇 |
2008年 | 4031篇 |
2007年 | 4206篇 |
2006年 | 3939篇 |
2005年 | 3941篇 |
2004年 | 3570篇 |
2003年 | 3166篇 |
2002年 | 2944篇 |
2001年 | 967篇 |
2000年 | 1045篇 |
1999年 | 839篇 |
1998年 | 436篇 |
1997年 | 367篇 |
1996年 | 342篇 |
1995年 | 314篇 |
1994年 | 260篇 |
1993年 | 194篇 |
1992年 | 333篇 |
1991年 | 295篇 |
1990年 | 258篇 |
1989年 | 211篇 |
1988年 | 167篇 |
1987年 | 173篇 |
1986年 | 170篇 |
1985年 | 166篇 |
1984年 | 115篇 |
1983年 | 113篇 |
1982年 | 117篇 |
1981年 | 81篇 |
1980年 | 86篇 |
1979年 | 76篇 |
1978年 | 71篇 |
1977年 | 53篇 |
1976年 | 54篇 |
1974年 | 58篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Karen Falloon C Raina Elley Antonio Fernando III Arier C Lee Bruce Arroll 《The British journal of general practice》2015,65(637):e508-e515
Background
Insomnia is common in primary care. Cognitive behavioural therapy for insomnia (CBT-I) is effective but requires more time than is available in the general practice consultation. Sleep restriction is one behavioural component of CBT-I.Aim
To assess whether simplified sleep restriction (SSR) can be effective in improving sleep in primary insomnia.Design and setting
Randomised controlled trial of patients in urban general practice settings in Auckland, New Zealand.Method
Adults with persistent primary insomnia and no mental health or significant comorbidity were eligible. Intervention patients received SSR instructions and sleep hygiene advice. Control patients received sleep hygiene advice alone. Primary outcomes included change in sleep quality at 6 months measured by the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI), and sleep efficiency (SE%). The proportion of participants reaching a predefined ‘insomnia remission’ treatment response was calculated.Results
Ninety-seven patients were randomised and 94 (97%) completed the study. At 6-month follow-up, SSR participants had improved PSQI scores (6.2 versus 8.4, P<0.001), ISI scores (8.6 versus 11.1, P = 0.001), actigraphy-assessed SE% (difference 2.2%, P = 0.006), and reduced fatigue (difference −2.3 units, P = 0.04), compared with controls. SSR produced higher rates of treatment response (67% [28 out of 42] versus 41% [20 out of 49]); number needed to treat = 4 (95% CI = 2.0 to 19.0). Controlling for age, sex, and severity of insomnia, the adjusted odds ratio for insomnia remission was 2.7 (95% CI = 1.1 to 6.5). There were no significant differences in other outcomes or adverse effects.Conclusion
SSR is an effective brief intervention in adults with primary insomnia and no comorbidities, suitable for use in general practice. 相似文献992.
Wulin Teo Andrew V. Caprariello Megan L. Morgan Antonio Luchicchi Geert J. Schenk Jeffrey T. Joseph Jeroen J. G. Geurts Peter K. Stys 《Proceedings of the National Academy of Sciences of the United States of America》2021,118(8)
The molecular composition of myelin membranes determines their structure and function. Even minute changes to the biochemical balance can have profound consequences for axonal conduction and the synchronicity of neural networks. Hypothesizing that the earliest indication of myelin injury involves changes in the composition and/or polarity of its constituent lipids, we developed a sensitive spectroscopic technique for defining the chemical polarity of myelin lipids in fixed frozen tissue sections from rodent and human. The method uses a simple staining procedure involving the lipophilic dye Nile Red, whose fluorescence spectrum varies according to the chemical polarity of the microenvironment into which the dye embeds. Nile Red spectroscopy identified histologically intact yet biochemically altered myelin in prelesioned tissues, including mouse white matter following subdemyelinating cuprizone intoxication, as well as normal-appearing white matter in multiple sclerosis brain. Nile Red spectroscopy offers a relatively simple yet highly sensitive technique for detecting subtle myelin changes.Myelin is a highly ordered, lipid-rich extension of glial cell membrane that facilitates rapid and efficient saltatory conduction of action potentials along axons in the central and peripheral nervous systems. The stability of myelin membranes critically depends on its molecular composition (1–3). Although myelin is maintained roughly at a ratio of 70:30% lipid to protein (4), lipid membranes are highly fluid; changes in lipid composition are defining characteristics of myelin development (5), homeostasis in the adult, and aging in rodents (6, 7), as well as primates (8). Shifts in lipid composition also occur in inflammatory demyelinating disorders like multiple sclerosis (MS) (9, 10). Lipids are even theorized to be targets of immune attacks in autoimmune disorders, a role previously ascribed to proteins (11). Key roles for lipids notwithstanding, tools to interrogate biochemical changes to myelin lipids have largely been restricted to in vitro systems.Once thought to be inert, myelin is now known to be a chemically and structurally dynamic element (12). Specific combinations of proteins and lipids induce formation and compaction of multilamellar vesicles that resemble myelin (13), underscoring the importance of correct chemical composition for assembly. Conversely, alterations in these molecular proportions promote decompaction and myelin vesiculation (3, 14). The polarity of lipid species in cell membranes influences their packing properties and therefore stability (15). Governed by competing thermodynamic forces of lipid curling and hydrocarbon packing (16), myelin sheaths lie at the critical edge of bilayer stability and thus are susceptible to factors in the environment. Indeed, the myelin integrity theory of MS rests on the outsized influence of environmental forces on myelin stability and function (17). Therefore, methods for detecting physicochemical changes in myelin lipid composition in situ would greatly enhance our understanding of early events in myelin development, as well as myelin damage in disease states, with important implications for therapies designed to prevent myelin loss in MS and other demyelinating disorders.The study of myelin lipid biochemistry poses unique challenges (18). Traditional analytical methods, such as thin-layer chromatography and high-performance liquid chromatography (19), depend on tissue homogenization that eliminates informative spatial relationships. Imaging lipid mass spectrometry (20) preserves spatial relationships, but submicron resolution has yet to be realized, and reproducibility at the level of sample preparation remains problematic (21). Coherent anti–Stokes Raman scattering microscopy provides high-resolution, label-free imaging of lipids in histological samples (22), but this method lacks sensitivity and requires expertise in nonlinear optics as well as highly specialized hardware. Finally, fluorescent lipophilic dyes, though widely available and easy to use, have traditionally been employed to detect lipid-rich structures in only a qualitative manner. Conventional fluorescence microscopy is therefore unable to detect subtle shifts in lipid biochemistry. By contrast, Nile Red (NR) is a fluorescent dye that is well situated to report changes in the chemical polarity of cell membranes and myelin, being both lipophilic (23, 24) and differentially fluorescent depending on solvent environment (i.e., exhibits solvatochromism) (25). The current study uses NR fluorescence spectroscopy to identify polarity shifts as an early manifestation of myelin disease prior to overt demyelination. We show that this technique reports subtle biochemical changes in myelin, resulting in a method that is a very sensitive marker of incipient myelin injury. 相似文献
993.
Sabino Puente German Ramirez-Olivencia Mar Lago Mercedes Subirats Eugenio Perez-Blazquez Fernando Bru Teresa Garate Belén Vicente Moncef Belhassen-Garcia Antonio Muro 《Enfermedades infecciosas y microbiología clínica》2018,36(10):633-639
Introduction
Onchocerciasis is caused by Onchocerca volvulus and mainly leads to pruritus and skin and visual disorders, including blindness. Seventeen million people are infected in 38 countries; 31 of these are in sub-Saharan Africa, six in Latin America and one on the Arabian Peninsula. More than 99% of cases occur in sub-Saharan Africa where 120 million people are at risk of infection. Eye disorders have been well-documented; however, skin disorders have not been described accurately. The objective of our study was to describe the epidemiology, main skin manifestations and treatment of imported onchocerciasis.Material and methods
A retrospective study was thus conducted by analysing the main demographic, clinical and treatment data regarding a cohort of 400 patients attending a reference clinical unit over a 17-year period.Results
Most patients were female (55%) with mean age 37.5 ± 16.7 years. All the migrants came from sub-Saharan countries. The most frequently occurring dermatological symptom was pruritus. Ivermectin had been used as first-line therapy and adverse reactions had been described in 11 patients (3.2%).Conclusions
The results indicate the fact that there should be a clinical suspicion of onchocerciasis regarding immigrants from endemic areas having skin lesions compatible with the disease's profile or asymptomatic patients having eosinophilia or unexplained high IgE. Moreover, skin snips from the buttocks region were very fruitful and treatment with ivermectin was seen to be safe. This is the largest case series regarding imported onchocerciasis described up to the present time. 相似文献994.
Sex differences in uric acid metabolism in adults: evidence for a lack of influence of estradiol-17 beta (E2) on the renal handling of urate 总被引:1,自引:0,他引:1
F M Antón J García Puig T Ramos P González J Ordás 《Metabolism: clinical and experimental》1986,35(4):343-348
The serum urate concentration of adult women, which is lower than in men of a similar age, is thought to be related to a higher renal clearance of urate in women, possibly due to their higher plasma estrogen levels. Intersexual differences in the renal handling of uric acid was assessed in 9 normal adult women and 9 normal age-matched men. Women showed a significantly lower serum urate concentration as compared to men (3.5 +/- 0.3 v 4.9 +/- 0.7 mg/dL, P less than 0.001), higher fractional excretion of urate (9.8 +/- 1.0 v 7.3 +/- 0.8%, P less than 0.001), and significantly lower tubular urate postsecretory reabsorption (67.2 +/- 1.6 v 76.6 +/- 1.4% of secreted urate, P less than 0.01). To test whether plasma E2 has a uricosuric effect we administered estradiol valerate and estradiol benzoate to either oophorectomized or adult women. Plasma E2 levels and urinary total estrogen excretion increased significantly in both groups but the treatment failed to significantly modify serum urate or the fractional excretion of uric acid. Furthermore, in 4 normal adult women, the tubular phases that modulate the renal excretion of urate were not significantly influenced by increased plasma E2 levels. We conclude that in comparison to men of a similar age, the lower tubular urate postsecretory reabsorption of adult women is in accordance with the intersexual differences in uric acid metabolism. Plasma E2 does not influence renal handling of uric acid or serum urate levels. 相似文献
995.
A randomized controlled trial of Pivotal Response Treatment Group for parents of children with autism 下载免费PDF全文
996.
Martín-Carbonero L Puoti M García-Samaniego J De Luca A Losada E Quinzan G Bruno R Mariño A González M Núñez M Soriano V 《Journal of viral hepatitis》2008,15(10):710-715
SUMMARY: Hepatitis C virus (HCV) genotypes 1 and 4 respond less well to pegylated interferon (pegIFN) plus ribavirin (RBV) therapy. For this reason most studies merge these two genotypes when assessing virological response. However, in most trials the HCV genotype 4 population is rather small, and conclusions are mainly derived from what occurs in HCV-1 patients. All HCV-4 patients coinfected with HIV who received pegIFN plus RBV in two different multicentre studies, PRESCO and ROMANCE, conducted respectively in Spain and Italy, were retrospectively analyzed. Baseline plasma HCV-RNA, proportion of patients with HCV-RNA <10 IU / mL at week 4 (rapid virological response), and HCV-RNA declines >2 logs at week 12 (early virological response, EVR) were all assessed as predictors of sustained virological response (SVR). Overall, 75 patients (60 men) were evaluated. Median age was 40 years and median CD4 count 598 cells / mm(3); 49% had plasma HIV-RNA <50 copies / mL; 71% had elevated liver enzymes and 31% had advanced liver fibrosis (Metavir F3-F4). Median serum HCV-RNA was 5.7 log IU / mL. Rapid virological response was attained by 10 (20%) patients and EVR by 26 (42%). Using intention-to-treat and on-treatment (OT) analyses, SVR was achieved by 21 / 75 (28%) and 21 / 62 (34%) of HCV-4 patients, respectively. In the multivariate analysis (OT), baseline HCV-RNA (OR 0.09 for every log increment; 95% CI: 0.01-0.7) and EVR (OR: 7.08; 95% CI: 1.8-27.2) were significantly and independently associated with SVR. This is the largest series of HIV-infected patients with chronic hepatitis C due to HCV-4 treated with pegIFN plus RBV examined so far and the results show that HCV-4 behaves similarly to HCV-1. Therefore, these patients should be considered as difficult to treat population. Baseline serum HCV-RNA and EVR are the best predictors of SVR in HCV-4 / HIV-coinfected patients. 相似文献
997.
A comparison of the performance characteristics of classification criteria for the diagnosis of psoriatic arthritis 总被引:5,自引:0,他引:5
Taylor WJ Marchesoni A Arreghini M Sokoll K Helliwell PS 《Seminars in arthritis and rheumatism》2004,34(3):575-584
OBJECTIVE: To compare the accuracy of published classification criteria for the diagnosis of psoriatic arthritis (PsA) and to see whether data-derived classification criteria would be more accurate. METHODS: Data were abstracted from case-note review and radiographic review of patients identified with PsA or rheumatoid arthritis (RA) from 2 clinical disease registers. Each patient was classified according to 7 criteria sets. The test performance characteristics were compared using conditional logistic regression analysis. In an attempt to overcome the problems of the diagnostic gold standard, latent class analysis also was used to calculate test-performance characteristics. Classification and regression-tree methodology was used to derive new criteria and to indicate the diagnostic importance of particular data items, especially rheumatoid factor (RF). RESULTS: Four hundred ninety-nine patients were identified with RA (n=156) or PsA (n=343). Excluding the criteria of Fournie, which could not be applied in 24% of subjects, 446 cases could be classified by all of the other 6 methods. The most sensitive criteria for the diagnosis of PsA were those of Vasey and Espinoza, McGonagle, and Gladman (99%), whereas the others were significantly less sensitive (between 56% and 94%). The specificity of the criteria was high and statistically similar (between 93% and 99%). The Fournie criteria were the most difficult to use, whereas the Vasey and Espinoza and Moll and Wright criteria were the easiest (98% of subjects were able to be classified). A 2-latent class model found very similar test-performance characteristics. Logistic regression and classification and regression-tree models suggested that negative RF was not necessary for diagnosis in the presence of other characteristic features of PsA. CONCLUSIONS: Apart from the Bennett and European Spondyloarthropathy Study Group criteria, which have inadequate sensitivity, the published classification criteria for PsA have similar test-performance characteristics. These data suggest that the criteria proposed by Vasey and Espinoza, Gladman, or McGonagle are the most accurate and feasible in distinguishing between PsA and RA. Relevance International agreement about classification criteria for PsA will assist the interpretation of clinical and epidemiologic research. However, further prospective studies on unselected patients with and without PsA, including controls with non-rheumatoid inflammatory arthritis, are required to confirm these findings. 相似文献
998.
Fernández A Quintana G Matteson EL Restrepo JF Rondón F Sánchez A Iglesias A 《Clinical rheumatology》2004,23(6):523-526
Systemic lupus erythematosus is an autoimmune and inflammatory disease with multiple clinical manifestations, including arthropathy. The clinical presentation of articular involvement is variable, ranging from arthralgia without erosions or deformity to an erosive arthropathy and severe functional disability. A subset of patients with this articular involvement have Jaccouds arthropathy, and others have an arthropathy with clinical findings similar to rheumatoid arthritis that has been called rhupus. In this paper we review the historical evolution of concepts of lupus arthropathy, from deforming arthritis to rhupus, and conclude that rhupus is not a combination of rheumatoid arthritis and lupus. Instead, rhupus arthropathy should be regarded as a variant of the arthropathy of systemic lupus erythematosus. 相似文献
999.
Contrast medium in power Doppler ultrasound for assessment of synovial vascularity: comparison with arthroscopy 总被引:3,自引:0,他引:3
Fiocco U Ferro F Cozzi L Vezzù M Sfriso P Checchetto C Bianchi FC Nardacchione R Piccoli A Todesco S Rubaltelli L 《The Journal of rheumatology》2003,30(10):2170-2176
OBJECTIVE: To evaluate the reliability of contrast-unenhanced power Doppler (CUPD) and contrast-enhanced power Doppler (CEPD) ultrasound (US) assessment of synovial vascularity of knee joint synovitis by prospective comparison with the "gold standard," arthroscopy. METHODS: A total of 18 knees of 17 patients with refractory rheumatoid and psoriatic knee joint synovitis were examined by US. Recognition of PD synovial vessel flow and its spatial arrangement in relation to the pannus/cartilage interface (P/CI) or fluid/synovium interface (F/SI) were studied by CUPD- and CEPD-US after a single intravenous bolus of galactosel palmitic acid (Levovist). Arthroscopy video recordings were reanalyzed by computer image analysis to assess synovial vascular marking. CUPD and CEPD flow signal scores were compared with each other and with corresponding vascular marking scores. Using villous vascular marking as reference, CUPD and CEPD sensitivity and specificity were measured. Interobserver variability was evaluated. RESULTS: Compared with the unenhanced PD method, contrast administration increased the PD flow signal score in 13/18 knees (72.2%), allowing increased detection of F/SI PD flow signal configuration (p < 0.018) and of the coexistence of P/CI and F/SI PD imaging (p < 0.0078). With arthroscopy as reference, contrast-enhanced PD was found to be more useful than the unenhanced method, showing more reproducible PD signal scores (p = 0.05 vs p = nonsignificant), as well as higher sensitivity (80% vs 30%), but lower specificity (62% vs 87%), in the recognition of increased vascularity of synovial villi. Interobserver agreement was 100%. CONCLUSION: The prospective comparison with arthroscopy showed the reliability of the CEPD method in synovial vessel recognition and its potential clinical usefulness in assessment of knee joint synovitis. 相似文献
1000.
Dejan Orlic Bernhard Reimers Goran Stankovic Nicola Corvaja Alaide Chieffo Flavio Airoldi Vassilis Spanos Luca Favero Carlo Di Mario Antonio Colombo 《Catheterization and cardiovascular interventions》2003,60(2):159-166
The purpose of this study was to evaluate the safety and efficacy of the new Fox Hollow atherectomy device (FHT) designed for more efficient and easier plaque removal. The FHT has short rigid section and low-profile cutter mounted on a monorail catheter. The FHT catheter was utilized in 77 patients with 98 lesions. Mean reference vessel diameter was 2.75 +/- 0.51 mm. Successful atherectomy with tissue retrieval was performed in 94 lesions (96%). Following atherectomy, mean diameter stenosis was reduced from 71.1% to 31.9% and further to 10.4% following adjunctive treatment. Angiographic complications were one coronary perforation and one adventitial staining, both successfully treated with prolong balloon inflation and stent implantation. Nine patients (11.7%) had in-hospital non-Q-wave myocardial infarction (MI). One patient died (1.3%) for noncardiac reasons and one had MI (1.3%) at 6-month follow-up. Target lesion revascularization was required in 13 (13.8%) lesions and target vessel revascularization in 15 (20.3%) patients. There was target vessel failure in 17 (23.0%) patients. Plaque debulking with the FHT catheter can be performed safely and effectively in relatively small vessels and complex lesions located in mid-distal artery segments with 6-month clinical outcome similar to prior atherectomy devices. 相似文献