全文获取类型
收费全文 | 40738篇 |
免费 | 1971篇 |
国内免费 | 278篇 |
专业分类
耳鼻咽喉 | 349篇 |
儿科学 | 1238篇 |
妇产科学 | 936篇 |
基础医学 | 4819篇 |
口腔科学 | 1199篇 |
临床医学 | 2970篇 |
内科学 | 10768篇 |
皮肤病学 | 621篇 |
神经病学 | 3844篇 |
特种医学 | 1693篇 |
外国民族医学 | 3篇 |
外科学 | 6164篇 |
综合类 | 137篇 |
一般理论 | 12篇 |
预防医学 | 1984篇 |
眼科学 | 491篇 |
药学 | 2231篇 |
中国医学 | 69篇 |
肿瘤学 | 3459篇 |
出版年
2023年 | 317篇 |
2022年 | 683篇 |
2021年 | 1244篇 |
2020年 | 688篇 |
2019年 | 995篇 |
2018年 | 1305篇 |
2017年 | 885篇 |
2016年 | 1070篇 |
2015年 | 1180篇 |
2014年 | 1622篇 |
2013年 | 1986篇 |
2012年 | 3180篇 |
2011年 | 3092篇 |
2010年 | 1844篇 |
2009年 | 1609篇 |
2008年 | 2773篇 |
2007年 | 2624篇 |
2006年 | 2627篇 |
2005年 | 2432篇 |
2004年 | 2230篇 |
2003年 | 2021篇 |
2002年 | 1940篇 |
2001年 | 317篇 |
2000年 | 245篇 |
1999年 | 350篇 |
1998年 | 354篇 |
1997年 | 297篇 |
1996年 | 262篇 |
1995年 | 268篇 |
1994年 | 214篇 |
1993年 | 216篇 |
1992年 | 174篇 |
1991年 | 142篇 |
1990年 | 160篇 |
1989年 | 126篇 |
1988年 | 118篇 |
1987年 | 94篇 |
1986年 | 123篇 |
1985年 | 90篇 |
1984年 | 130篇 |
1983年 | 91篇 |
1982年 | 106篇 |
1981年 | 80篇 |
1980年 | 85篇 |
1979年 | 56篇 |
1978年 | 68篇 |
1977年 | 43篇 |
1976年 | 40篇 |
1973年 | 38篇 |
1972年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Tim C. van den Beukel Carlo Lucci Jeroen Hendrikse Wilko Spiering Huiberdina L. Koek Mirjam I. Geerlings Pim A. de Jong 《Journal of neuroradiology. Journal de neuroradiologie》2021,48(4):248-253
Background and purposeVertebrobasilar artery calcification (VBAC) has been associated with increased stroke occurrence. Little is known on VBAC risk factors, especially for patients with cardiovascular disease. We aimed to assess risk factors associated with VBAC in a cohort of cardiovascular patients referred for a head computed tomography (CT) scan.Materials and methodsAll patients who underwent a clinically indicated, unenhanced, thin slice head CT 6 months before or after inclusion in the SMART study were included. CTs were assessed for presence of VBAC (dichotomously). Relative risks of the associations of age, sex, diabetes mellitus (DM), obesity, body mass index, estimated glomerular filtration rate, hypertension, hyperlipidemia, use of lipid lowering medication, smoking status, high sensitivity C-reactive protein, ankle-brachial index (ABI; ≤ 0.90, ≥ 1.30, continuous), internal carotid artery stenosis ≥ 70%, and carotid intima-media thickness (IMT) with VBAC were estimated using Poisson regression analysis with robust standard errors, adjusted for age and sex.ResultsOf the 471 patients included (57% male, median age 58 [interquartile range 47–63]), 117 (24.8%) showed VBAC. Presence of VBAC was associated with older age (RR per 10 years = 1.70 [95%CI 1.46–1.99]), DM (RR = 1.45 [95%CI 1.03–2.06]), obesity (RR = 1.53 [95%CI 1.10–2.12]), ABI ≤ 0.90 (RR = 1.57 [95%CI 1.02–2.41]), and an increased carotid IMT (RR = 2.60 per mm [95%CI 1.20–5.62]). Other measurements were not associated with VBAC.ConclusionsWe identified several markers associated with VBAC in patients with cardiovascular disease referred for a head CT. Future investigation into the relationship between VBAC and stroke is warranted to determine the potential of VBAC in stroke prevention. 相似文献
942.
Emilie Montellier Fay?al Boussouar Sophie Rousseaux Kai Zhang Thierry Buchou Fran?ois Fenaille Hitoshi Shiota Alexandra Debernardi Patrick Héry Sandrine Curtet Mahya Jamshidikia Sophie Barral Hélène Holota Aurélie Bergon Fabrice Lopez Philippe Guardiola Karin Pernet Jean Imbert Carlo Petosa Minjia Tan Yingming Zhao Matthieu Gérard Saadi Khochbin 《Genes & development》2013,27(15):1680-1692
The conversion of male germ cell chromatin to a nucleoprotamine structure is fundamental to the life cycle, yet the underlying molecular details remain obscure. Here we show that an essential step is the genome-wide incorporation of TH2B, a histone H2B variant of hitherto unknown function. Using mouse models in which TH2B is depleted or C-terminally modified, we show that TH2B directs the final transformation of dissociating nucleosomes into protamine-packed structures. Depletion of TH2B induces compensatory mechanisms that permit histone removal by up-regulating H2B and programming nucleosome instability through targeted histone modifications, including lysine crotonylation and arginine methylation. Furthermore, after fertilization, TH2B reassembles onto the male genome during protamine-to-histone exchange. Thus, TH2B is a unique histone variant that plays a key role in the histone-to-protamine packing of the male genome and guides genome-wide chromatin transitions that both precede and follow transmission of the male genome to the egg. 相似文献
943.
Pietro Invernizzi Simone Pasini Carlo Selmi Monica Miozzo Mauro Podda 《Autoimmunity》2013,46(4):272-277
Approximately 5% of the population in Western countries is affected by autoimmune diseases (AID), with a significantly higher prevalence in women. Genetic factors are known to be crucial determinants of susceptibility as shown by family and twin studies, although no specific genes predisposing women to autoimmunity have been identified thus far. Several studies indicate that X chromosome abnormalities, such as inactivation patterns, characterize some female-predominant AID. We herein review the most recent evidence on the role of the X chromosome in the breakdown of immune tolerance and discuss its potential implications. Future efforts will help to identify specific X chromosome regions containing candidate genes for disease susceptibility. 相似文献
944.
Fabiola Atzeni Fabiola Atzeni Andrea Doria Anna Ghirardello Maurizio Turiel Alberto Batticciotto 《Autoimmunity》2013,46(1):111-115
Objectives: The aim of this study was to assess thyroid function as well as the prevalence and clinical value of anti-thyroid antibodies in patients with rheumatoid arthritis (RA).Methods: Seventy patients with active RA (ACR criteria), 9 males and 61 females, mean age 47 years (range 15–77) were analyzed. Anti-thyroperoxidase (TPOAb) and anti-thyroglobulin antibodies (TgAb) were tested using radioimmunoassay. Free thyroxine (FT4) and free triiodothyronine (FT3) and thyroid-stimulating hormone (TSH) serum levels were measured using electro-immunochemiluminescence (ECLIA, Elecsys Roche). Clinical variables, including tender and swollen joint count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), anti-cyclic citrullinated peptide antibody (anti-CCP) and antinuclear antibodies (ANA) were also evaluated. Statistics were performed by the SPSS statistical software for Windows.Results: Twenty-six patients (37%) with RA were positive for TPOAb and 16 (23%) for TgAb. In 5 (7.1%) patients TSH level was slightly elevated, ranging between 4.52 and 15.65 UI/ml. The increase of TSH levels was associated with normal FT4 in 3 cases (4.2%) and with reduced FT4 in 2 cases (2.8%). One patient (1.5%) had low TSH serum value along with normal FT4. No differences in clinical and serological data between anti-thyroid positive and negative patients were observed.Conclusion: Our study shows an increased prevalence of anti-thyroid antibodies in RA patients with a low prevalence of hormonal alterations. However, anti-thyroid antibodies do not seem to identify any peculiar RA phenotype. 相似文献
945.
Maria A. Panaro Carlo I. Mitolo Angela Acquafredda Antonia Cianciulli Sabrina Lisi Chiara Porro 《Immunopharmacology and immunotoxicology》2013,35(3):475-488
Six representative CXCR4 mRNAs of fish, amphibia, birds, and mammals were selected to study the pattern of conservation/mutation of the individual nt of the coding sequences. According to an arbitrary conservation index ranging from 1 to 6, the indexes of conservation were: 5.04 for the first nt of coding triplets; 5.34 for the second nt of triplets, and 3.75 for the third nt of triplets. The average conservation index of the individual triplets was 4.71. The conservation index of the seven hydrophobic transmembrane domains was 5.60, while the cumulative conservation index of the intracytoplasmic and extracellular domains was 4.63. Separate autocorrelation and power spectral analyses of the series of conservation indexes for the first nt, the second nt and the triplets demonstrated a modest “basic” positive correlation for about the first 20 lags and accordingly some power concentration at the lower frequencies (long periods). Within the triplets, the correlation was studied between the conservation indexes of nt 1 and 2, 1 and 3, and 2 and 3. Correlations of 1 with 3 and 2 with 3 were positive, but in the range of the basic local correlation, whereas the correlation between the first and second nt was significantly higher. This correlation, together with the higher conservation of the second nt as compared to the first (two patterns also found in the formyl peptide receptors), are likely to have been established by selection processes directed towards a functional conservation or a “functional repair.” 相似文献
946.
Muhammed Babakir‐Mina Massimo Ciccozzi Carlo Federico Perno Marco Ciotti 《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》2013,121(8):746-754
In 2007, two novel polyomaviruses KI and WU were uncovered in the respiratory secretions of children with acute respiratory symptoms. Seroepidemiological studies showed that infection by these viruses is widespread in the human population. Following these findings, different biological specimens and body compartments have been screened by real‐time PCR in the attempt to establish a pathogenetic role for KI polyomavirus (KIPyV) and WU polyomavirus (WUPyV) in human diseases. Although both viruses have been found mainly in respiratory tract samples of immunocompromised patients, a clear causative link with the respiratory disease has not been established. Indeed, the lack of specific clinical or radiological findings, the frequent co‐detection with other respiratory pathogens, the detection in subjects without signs or symptoms of respiratory disease, and the variability of the viral loads measured did not allow drawing a definitive conclusion. Prospective studies carried out on a large sample size including both immunocompromised and immunocompetent patients with and without respiratory symptoms are needed. Standardized quantitative real‐time PCR methods, definition of a clear clinical cutoff value, timing in the collection of respiratory samples, are also crucial to understand the pathogenic role, if any, of KIPyV and WUPyV in human pathology. 相似文献
947.
Alberto Martínez-Martínez Jade García-Espinosa Antonio Jesús Linez Ramos-Bossini Fernando Ruiz Santiago 《Korean journal of radiology》2021,22(6):944
ObjectiveTo demonstrate the feasibility of percutaneous microwave ablation in desmoid fibromatosis with respect to tumor volume control and improvement in the quality of life.Materials and MethodsTwelve microwave ablations were performed in 9 patients with a histological diagnosis of desmoid fibromatosis between January 2010 and January 2019. The study population included 6 female and 3 male, with an age range of 21–76 years (mean = 46.6 years; standard deviation [SD] = 19.3 years). The mean major axis of the tumors was 10.9 cm (SD = 5.2 cm) and mean lesion volume was 212.7 cm3 (SD = 213 cm3). Their anatomical distribution was as follows: 3 lesions in the thigh, 2 in the gluteus, 2 in the leg and 2 in the periscapular region. We evaluated the reduction in tumor volume and improvement in the quality of life based on the Eastern Cooperative Oncology Group (ECOG) scale.ResultsAn average tumor volume reduction of 70.4% (SD = 24.9) was achieved, while the quality of life (ECOG scale) improved in 88.9% of patients.ConclusionPercutaneous microwave ablation may potentially be a safe, effective, and promising technique for controlling tumor volume and improving the quality of life in patients with desmoid fibromatosis. 相似文献
948.
Todd C. Villines Subhi J. Al’Aref Daniele Andreini Marcus Y. Chen Andrew D. Choi Carlo N. De Cecco Damini Dey James P. Earls Maros Ferencik Heidi Gransar Harvey Hecht Jonathon A. Leipsic Michael T. Lu Mohamed Marwan Pál Maurovich-Horvat Edward Nicol Gianluca Pontone Jonathan Weir-McCall Gudrun M. Feuchtner 《Journal of Cardiovascular Computed Tomography》2021,15(2):180-189
949.
Loukia Katsouri Marcela P. Vizcaychipi Simon McArthur Ian Harrison Marc Suárez-Calvet Alberto Lleo Dafydd G. Lloyd Daqing Ma Magdalena Sastre 《Neurobiology of aging》2013
Noradrenergic deficits have been described in the hippocampus and the frontal cortex of Alzheimer's disease brains, which are secondary to locus coeruleus degeneration. Locus coeruleus is the brain stem nucleus responsible for synthesis of noradrenaline and from where all noradrenergic neurons project. In addition, it has been suggested that noradrenaline might play a role in modulating inflammatory responses in Alzheimer's disease. In this study we aimed to investigate the effect of various agonists and antagonists for adrenergic receptors on amyloid precursor protein processing. Among them, we found that prazosin, an α1-adrenoceptor antagonist, was able to reduce the generation of amyloid β in N2a cells. Treatment of transgenic APP23 mice with prazosin prevented memory deficits over time. Although prazosin did not influence amyloid plaque load, it induced astrocytic proliferation and increased the release of apolipoprotein E and anti-inflammatory cytokines. These findings suggest that chronic treatment with prazosin leads to an anti-inflammatory response with potential beneficial effects on cognitive performance. 相似文献
950.
Romagnolo Alberto Balestrino Roberta Imbalzano Gabriele Ciccone Giovannino Riccardini Franco Artusi Carlo Alberto Bozzali Marco Ferrero Bruno Montalenti Elisa Montanaro Elisa Rizzone Mario Giorgio Vaula Giovanna Zibetti Maurizio Lopiano Leonardo 《Journal of neurology》2021,268(3):762-769
Journal of Neurology - Neurological symptoms of COVID-19 patients have been recently described. However, no comprehensive data have been reported on pre-existing neurological comorbidities and... 相似文献