全文获取类型
收费全文 | 23002篇 |
免费 | 1196篇 |
国内免费 | 254篇 |
专业分类
耳鼻咽喉 | 252篇 |
儿科学 | 484篇 |
妇产科学 | 667篇 |
基础医学 | 2611篇 |
口腔科学 | 522篇 |
临床医学 | 1688篇 |
内科学 | 6227篇 |
皮肤病学 | 397篇 |
神经病学 | 2473篇 |
特种医学 | 890篇 |
外科学 | 3651篇 |
综合类 | 46篇 |
一般理论 | 4篇 |
预防医学 | 906篇 |
眼科学 | 281篇 |
药学 | 1353篇 |
中国医学 | 48篇 |
肿瘤学 | 1952篇 |
出版年
2024年 | 23篇 |
2023年 | 184篇 |
2022年 | 398篇 |
2021年 | 710篇 |
2020年 | 441篇 |
2019年 | 522篇 |
2018年 | 685篇 |
2017年 | 556篇 |
2016年 | 640篇 |
2015年 | 715篇 |
2014年 | 927篇 |
2013年 | 1121篇 |
2012年 | 1769篇 |
2011年 | 1791篇 |
2010年 | 1012篇 |
2009年 | 996篇 |
2008年 | 1619篇 |
2007年 | 1600篇 |
2006年 | 1455篇 |
2005年 | 1383篇 |
2004年 | 1352篇 |
2003年 | 1213篇 |
2002年 | 1073篇 |
2001年 | 153篇 |
2000年 | 121篇 |
1999年 | 166篇 |
1998年 | 185篇 |
1997年 | 165篇 |
1996年 | 166篇 |
1995年 | 132篇 |
1994年 | 88篇 |
1993年 | 96篇 |
1992年 | 97篇 |
1991年 | 77篇 |
1990年 | 71篇 |
1989年 | 85篇 |
1988年 | 55篇 |
1987年 | 71篇 |
1986年 | 64篇 |
1985年 | 41篇 |
1984年 | 64篇 |
1983年 | 53篇 |
1982年 | 39篇 |
1981年 | 42篇 |
1980年 | 42篇 |
1979年 | 21篇 |
1978年 | 15篇 |
1977年 | 24篇 |
1976年 | 15篇 |
1974年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Valentina Coia Barbara Sansonetti Giorgio Paoli Sergio Tofanelli Gabriella Spedini Giovanni Destro‐Bisol 《American journal of human biology》2002,14(1):9-14
Ten protein coding loci (6‐PGD, A1‐AT, ACP1, CaII, ESD, GC, GPX1, Hbβ, PGM1, and TF) were analyzed in the Mbenzele Pygmies from the Central African Republic. The frequency data were used to calculate the genetic distances between Mbenzele Pygmies and other African groups. In the principal coordinate plot of FST genetic distances, the Mbenzele cluster together with other Pygmies of the western cluster, the Biaka from C.A.R., Gielli from Cameroon, and Babinga from Congo. By contrast, they are considerably distanced from other Pygmy groups of the eastern cluster (Twa from Rwanda, Mbuti from Zaire). Genetic distances obtained using protein loci were compared with those based on microsatellite loci. The two distance matrices are insignificantly correlated (r = 0.268; one tail probability = 0.332), and the main difference is in the higher genetic affinity between the Mbenzele and Biaka Pygmies observed at the protein level. Although reasons underlying the discrepancy between inter‐populational variation at protein and DNA loci are not established with certainty, the comparison suggests that the genetic distance between the Mbenzele and Biaka Pygmies at microsatellite loci could have been shaped by genetic drift. Am. J. Hum. Biol. 14:9–14, 2002.© 2002 Wiley‐Liss, Inc. 相似文献
42.
Giovanni Corrao Antonella Zambon Lorenza Bertù Anna Mauri Valentina Paleari Camillo Rossi Mauro Venegoni 《Drug safety》2006,29(10):889-896
OBJECTIVE: To investigate the association between the use of fluoroquinolone agents and the risk of tendinitis in a large population-based case-control study. METHODS: The study was performed by linking automated health databases from the Region of Lombardia, Italy. Cases were patients aged > or =18 years who had a hospital discharge diagnosis of non-traumatic tendinitis in 2002-3. For each case, up to five controls were randomly selected among those eligible for inclusion in the study. A conditional logistic regression model was used to estimate the odds ratio of tendinitis associated with the current, recent and past use of fluoroquinolones. Odds ratios were adjusted for exposure to other antibacterials and other drugs. RESULTS: 22,194 cases and 104,906 controls met the inclusion criteria. Current use of fluoroquinolones significantly increased the risk of tendon disorders as a whole (odds ratio [OR] = 1.7; 95% CI 1.4, 2.0), tendon rupture (OR = 1.3; 95% CI 1.0, 1.8) and rupture of the Achilles' tendon (OR = 4.1; 95% CI 1.8, 9.6). Concomitant use of corticosteroids and fluoroquinolones increased the risk of both tendon rupture (OR = 3.1; 95% CI 1.5, 6.3) and rupture of the Achilles' tendon (OR = 43.2; 95% CI 5.5, 341.1). DISCUSSION: Evidence that exposure to fluoroquinolones is associated with the sudden occurrence of tendinitis is supported by this large population-based study. We can estimate that a single case of rupture of the Achilles' tendon would occur for every 5958 persons treated with fluoroquinolones (95% CI 2148, 23,085). The corresponding number needed to harm is 979 (95% CI 122, 9172) for patients who concomitantly use corticosteroids and 1638 (95% CI 351, 8843) for those aged >60 years. CONCLUSION: Clinicians should be aware of this adverse effect, and the increased risk for fluoroquinolone-associated tendinitis in elderly patients with corticosteroid use must be considered when these agents are prescribed. 相似文献
43.
Claudio Babiloni Giovanni Frisoni Mircea Steriade Lorena Bresciani Giuliano Binetti Claudio Del Percio Cristina Geroldi Carlo Miniussi Flavio Nobili Guido Rodriguez Filippo Zappasodi Tania Carfagna Paolo M Rossini 《Clinical neurophysiology》2006,117(5):1113-1129
OBJECTIVE: A relationship between brain atrophy and delta rhythmicity (1.5-4 Hz) has been previously explored in Alzheimer's disease (AD) subjects [Fernandez A, Arrazola J, Maestu F, Amo C, Gil-Gregorio P, Wienbruch C, Ortiz T. Correlations of hippocampal atrophy and focal low-frequency magnetic activity in Alzheimer disease: volumetric MR imaging-magnetoencephalographic study. Am J Neuroradiol. 2003 24(3):481-487]. In this study, we tested the hypothesis that such a relationship does exist not only in AD patients but also across the continuum of subjects with mild cognitive impairment (MCI) and AD. METHODS: Resting, eyes-closed EEG data were recorded in 34 MCI and 65 AD subjects. EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). EEG cortical sources were estimated by LORETA. Cortical EEG sources were correlated with MR-based measurements of lobar brain volume (white and gray matter). RESULTS: A negative correlation was observed between the frontal white matter and the amplitude of frontal delta sources (2-4 Hz) across MCI and AD subjects. CONCLUSIONS: These results confirmed for the first time the hypothesis that the sources of resting delta rhythms (2-4 Hz) are correlated with lobar brain volume across MCI and AD subjects. SIGNIFICANCE: The present findings support, at least at group level, the 'transition hypothesis' of brain structural and functional continuity between MCI and AD. 相似文献
44.
45.
Claudio Babiloni Rosanna Squitti Claudio Del Percio Emanuele Cassetta Maria Carla Ventriglia Florinda Ferreri Mario Tombini Giovanni Frisoni Giuliano Binetti Mariella Gurzi Serenella Salinari Filippo Zappasodi Paolo M Rossini 《Clinical neurophysiology》2007,118(6):1244-1260
OBJECTIVE: The present study tested the hypothesis that the serum copper abnormalities were correlated with alterations of resting electroencephalographic (EEG) rhythms across the continuum of healthy elderly (Hold), mild cognitive impairment (MCI), and AD subjects. METHODS: Resting eyes-closed EEG rhythms delta (2-4Hz), theta (4-8Hz), alpha 1 (8-10.5Hz), alpha 2 (10.5-13Hz), beta 1 (13-20Hz), beta 2 (20-30Hz), and gamma (30-40Hz), estimated by LORETA, were recorded in 17 Hold, 19 MCI, 27 AD- (MMSE< or =20), and 27 AD+ (MMSE20) individuals and correlated with copper biological variables. RESULTS: Across the continuum of Hold, MCI and AD subjects, alpha sources in parietal, occipital, and temporal areas were decreased, while the magnitude of the delta and theta EEG sources in parietal, occipital, and temporal areas was increased. The fraction of serum copper unbound to ceruloplasmin positively correlated with temporal and frontal delta sources, regardless of the effects of age, gender, and education. CONCLUSIONS: These results sustain the hypothesis of a toxic component of serum copper that is correlated with functional loss of AD, as revealed by EEG indexes. SIGNIFICANCE: The present study represents the first demonstration that the fraction of serum copper unbound to ceruloplasmin is correlated with cortical delta rhythms across Hold, MCI, and AD subjects, thus unveiling possible relationships among the biological parameter, advanced neurodegenerative processes, and synchronization mechanisms regulating the relative amplitude of selective EEG rhythms. 相似文献
46.
Non-specific bronchial hyper-responsiveness in children with allergic rhinitis: Relationship with the atopic status 总被引:1,自引:0,他引:1
Giuseppina Cuttitta Fabio Cibella Stefania La Grutta Maria R. Hopps Salvatore Bucchieri Giovanni Passalacqua Giovanni Bonsignore 《Pediatric allergy and immunology》2003,14(6):458-463
An increased prevalence of bronchial hyper-responsiveness (BHR) has been demonstrated in children from a general population, and in non-asthmatic adults with allergic rhinitis. Thus, also children with allergic rhinitis are expected to be at higher risk of BHR. We evaluated the prevalence of BHR in a sample of non-asthmatic children with allergic rhinitis by means of the methacholine (Mch) bronchial challenge, and by monitorizing the airway patency using the daily peak expiratory flow variability (PEFv). Fifty-one children (ranged 6–15 years of age) with allergic rhinitis, ascertained by skin prick test to inhalant allergens, underwent a 14-day peak expiratory flow monitoring, and a Mch bronchial provocation challenge. Thirty healthy children matched for age, and sex served as control group. Thirty-one children in the rhinitis group (61%), and six (20%) in the control group were Mch+ (Mch provocative dose causing a 20% fall of forced expiratory volume in 1 s respect to baseline <2250 μ g, equivalent to 11.50 μ mol). In rhinitic children the PEFv did not significantly differ between Mch+ and Mch− subjects, but the total serum immunoglobulin E (IgE) were higher among Mch+. The persistent form of rhinitis was significantly associated to Mch positivity. Non-asthmatic children with allergic rhinitis displayed a high prevalence of BHR. The BHR was significantly associated with persistent rhinitis and with higher total IgE levels. Nevertheless, the spontaneous changes in airway patency, as expressed by PEFv, were within normal limits both in Mch+ and Mch− children. 相似文献
47.
Treatment of type B aortic dissection: endoluminal repair or conventional medical therapy? 总被引:4,自引:0,他引:4
Giovanni Dialetto Franco E Covino Giancarlo Scognamiglio Sabrina Manduca Alessandro Della Corte Bruno Giannolo Michelangelo Scardone Maurizio Cotrufo 《European journal of cardio-thoracic surgery》2005,27(5):826-830
OBJECTIVE: To evaluate the mid-term results of endovascular stent-grafting for type B aortic dissection, in comparison with those of standard medical therapy in uncomplicated cases. METHODS: Between January 1999 and 2004, among 56 patients (mean age 59.5+/-11.5 years) with type B aortic dissection, hypotensive medical therapy was the only treatment in 28 uncomplicated cases, (group A), while stent-graft implantation was performed in 28 patients with uncontrolled hypertension, persistent pain or evidence of dissection progression or complication (group B). In 14 cases (50%) the procedure was performed in an acute setting. Stent-grafting procedures were monitored with intraoperative trans-esophageal echocardiography and cine-angiography. CT scan and trans-esophageal echocardiography were performed before hospital discharge, at 6 and 12 months and then yearly. RESULTS: Follow-up (range 1-61 months, average 18.1+/-16.9 months) was 100% complete. In-hospital mortality was 10.7% (three patients, all belonging to Group B; P=0.24). No spinal cord injuries were observed. Early endoleak occurred in one patient (3.5%). Mid-term mortality was lower in Group B, although the difference was not significant (10.7 versus 14.3% in Group A, P=0.71). Follow-up CT scans evidenced complete thrombosis of the false lumen in 75% cases in Group B, 10.7% in Group A (P=0.0001), and an aneurismal dilatation of the descending aorta in 3.5% cases in Group B, 28.5% in Group A (P=0.02). CONCLUSIONS: Although with still considerable early mortality, endovascular stent-graft implantation is an effective option for the treatment of complicated type B aortic dissection. Endovascular treatment achieved a better mid-term fate of the descending thoracic aorta than medical therapy alone, even in patients with worse preoperative conditions. 相似文献
48.
Marco Frattini Enrico Vaienti Giovanni Soncini Francesco Pogliacomi 《Musculoskeletal surgery》2009,93(3):109-114
Tibial plateau fractures are complex injuries which, if not adequately treated, can lead to invalidating sequelae. They constitute
on average about 1% of all fractures, and up to 8% in patients over 65 years, and can be caused by both high- and low-energy
trauma. Unlike in younger subjects, treatment of tibial plateau fractures in the elderly is not univocal and depends on the
patient’s functional needs, bone quality and systemic comorbidities. In this retrospective study, 49 patients with a mean
age of 72 years, who underwent surgical treatment of a tibial plateau fracture, were assessed by the Rasmussen’s clinical
and radiological grading systems. Clinical and radiographic outcomes were satisfactory in 75.5 and 59.1% of cases, respectively.
Data were also analyzed, in terms of fracture type, age and gender, to detect any statistically significant correlation between
these parameters and clinical and radiographic outcomes. 相似文献
49.
Giovanni Marchetto Andrea M. D'Armini Mauro Rinaldi Mario Vigan 《European journal of cardio-thoracic surgery》2005,27(6):1122-1124
Video-assisted minimally invasive cardiac surgery (VAMICS) is currently performed with various indications. However, despite the increasing evidence of its effectiveness, new approaches have to be defined to simplify this procedure, minimize its potential complications and limit its costs, for a wider use in the surgical community. The limited access to the aorta is a key point in VAMICS and mandates specific clamping modalities with their own limitations, costs and drawbacks. The Portaclamp (Cardio Life Research SA, Louvain la Neuve, Belgium), a new autoguided extravascular aortic cross-clamping system, has been recently proposed to facilitate VAMICS. Herein, we describe the Portaclamp approach and report our indications and preliminary clinical experience so to define its role in VAMICS. 相似文献
50.
Paolo Calabresi Emesto Fedele Antonio Pisani Giovanni Fontana Nicola B. Mercuri Giorgio Bernardi Maurizio Raiteri 《The European journal of neuroscience》1995,7(9):1889-1894
Using a corticostriatal slice preparation, we have recently shown that tetanic stimulation of the corticostriatal pathway produces long-term depression (LTD) of striatal excitatory synaptic transmission. In the present study we have analysed the relationship between LTD and the striatal release of different endogenous transmitters. Samples of perfusate were collected via a small cannula placed just above the surface of the striatal slice close to the recording electrode, and were analysed by HPLC. The high-frequency stimulation (100 Hz, three trains, 3 s duration, 20 s intervals) used to induce LTD caused a significant but transient increase in the release of both excitatory (aspartate and glutamate) and inhibitory (glycine and GABA) amino acid transmitters. Tetanic stimulation also produced a significant, but transient increase in the release of endogenous dopamine. We conclude that the tetanic stimulation of the corticostriatal pathway is able to induce a large but transient release of excitatory amino acids and of dopamine, whose participation in the induction of striatal LTD has been demonstrated previously. Moreover, the maintenance of this form of synaptic plasticity does not seem to require a sustained change in transmitter release. 相似文献