全文获取类型
收费全文 | 279434篇 |
免费 | 7434篇 |
国内免费 | 654篇 |
专业分类
耳鼻咽喉 | 2189篇 |
儿科学 | 10027篇 |
妇产科学 | 5413篇 |
基础医学 | 31655篇 |
口腔科学 | 5488篇 |
临床医学 | 21848篇 |
内科学 | 54339篇 |
皮肤病学 | 3361篇 |
神经病学 | 26782篇 |
特种医学 | 11372篇 |
外国民族医学 | 1篇 |
外科学 | 38237篇 |
综合类 | 2694篇 |
一般理论 | 48篇 |
预防医学 | 28042篇 |
眼科学 | 4431篇 |
药学 | 16773篇 |
中国医学 | 1047篇 |
肿瘤学 | 23775篇 |
出版年
2024年 | 91篇 |
2023年 | 1003篇 |
2022年 | 852篇 |
2021年 | 3752篇 |
2020年 | 2381篇 |
2019年 | 3184篇 |
2018年 | 24913篇 |
2017年 | 19643篇 |
2016年 | 22164篇 |
2015年 | 4388篇 |
2014年 | 5443篇 |
2013年 | 6786篇 |
2012年 | 15997篇 |
2011年 | 30070篇 |
2010年 | 23614篇 |
2009年 | 15713篇 |
2008年 | 26650篇 |
2007年 | 28796篇 |
2006年 | 7496篇 |
2005年 | 8632篇 |
2004年 | 9161篇 |
2003年 | 9457篇 |
2002年 | 7080篇 |
2001年 | 828篇 |
2000年 | 807篇 |
1999年 | 769篇 |
1998年 | 1003篇 |
1997年 | 861篇 |
1996年 | 644篇 |
1995年 | 562篇 |
1994年 | 519篇 |
1993年 | 414篇 |
1992年 | 328篇 |
1991年 | 287篇 |
1990年 | 317篇 |
1989年 | 259篇 |
1988年 | 225篇 |
1987年 | 184篇 |
1986年 | 179篇 |
1985年 | 149篇 |
1984年 | 156篇 |
1983年 | 147篇 |
1982年 | 179篇 |
1981年 | 112篇 |
1980年 | 166篇 |
1979年 | 78篇 |
1978年 | 87篇 |
1977年 | 71篇 |
1976年 | 66篇 |
1974年 | 72篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
61.
Diego Dias da Silva Ana Helena da Rosa Paz Ciro Paz Portinho Elizabeth Obino Cirne Lima Lúcia Maria Kliemann Marcus Vinicius Martins Collares 《Acta cirúrgica brasileira / Sociedade Brasileira para Desenvolvimento Pesquisa em Cirurgia》2020,35(12)
Purpose:This study assessed the regeneration potential of mesenchymal stem cells (MSC) from adipose tissue associated with platelet-rich plasma (PRP) in bone regeneration.Methods:Thirty Wistar rats (Rattus norvegicus albinos) were divided into five groups (according to the grafting material and time to euthanasia): (1) autograft - 14 days (control), (2) autograft - 28 days (control), (3) MSC + PRP - 14 days, (4) MSC + PRP + papaverine - 14 days and (5) MSC + PRP + papaverine - 28 days. After euthanasia, the graft was removed and histological slides were prepared. They were assessed by a blinded pathologist using a previously published histological scale as parameter.Results:There was some degree of neoformed bone trabeculae (NBT) in 93.3% of the samples, as well as osteoblastic activity (OA). The autograft groups (14 and 28 days) had higher levels in the formation of bone trabeculae. Nonparametric data were analyzed using the Wilcoxon-Mann-Whitney test and proved not to be statistically significant at p < 0.05.Conclusions:Experimental parietal bone reconstruction, combining MSC, PRP and papaverine presented regeneration in all groups with no significant difference among them.Key words: Bone Regeneration, Platelet-Rich Plasma, Tissue Engineering, Rats 相似文献
62.
63.
Marcelo Sato‐Sano Solange Pistori Teixeira Juliano Cordova Vargas Otvio Cesar Carvalho Guimares Baiocchi Milvia Maria Simes e Silva Enokihara Elimar Elias Gomes Mariana Dias Batista 《The Journal of dermatology》2019,46(7):618-621
Eosinophilic dermatosis of hematological malignancy is a paraneoplastic skin eruption associated with chronic lymphocytic leukemia and other B‐cell malignancies. It clinically resembles an insect bite reaction and it can precede the symptoms of the hematological malignancy or be related to a more aggressive course. Different treatments have been proposed, but partial response and recurrence are frequent. Herein, we describe a case of eosinophilic dermatosis associated with mantle cell lymphoma with remission after lenalidomide therapy. 相似文献
64.
Raffaella Marcheselli Alessia Bari Tamar Tadmor Luigi Marcheselli Maria Christina Cox Robel Papotti Angela Ferrari Luca Baldini Paolo Gobbi Ilana Levy Giuseppe Pugliese Massimo Federico Aaron Polliack Samantha Pozzi Stefano Sacchi 《Hematological oncology》2020,38(4):439-445
The main purpose of this study was to assess whether it is possible to improve the prognostic impact of international prognostic index (IPI) score by combining it with peripheral blood counts. Thus, we evaluated the prognostic power of lymphocyte, neutrophil, and monocyte counts in 520 patients with diffuse large B cell lymphoma treated with R-CHOP, confirming that these parameters have a strong impact on overall survival (OS). Using revised IPI (R-IPI), 44% of patients were categorized as poor-risk and showed an OS at 5 years of 46%. As OS at 5 years of the 520 patients is 67%, it is clearly evident that R-IPI tends to overestimate the proportion of patients with poor prognosis. Accordingly, in an attempt to improve the discriminating power of R-IPI, we evaluated and compared three different scores by combining the neutrophil lymphocyte ratio (NLR) and absolute monocyte count (AMC) with the following values: (a) IPI score 3-5, (b) age > 60 years and performance status, (c) age ≥ 65 years and LDH > ULN. The three indexes studied, had a similar 5 years OS for the high-risk group (46%-52%), but the proportion of patients classified as poor-risk were 37%, 20%, and 32%, respectively, which are lower than 44% identified with R-IPI. Thus, while R-IPI overestimates the number of high-risk patients, after applying our models, it is possible to recognize patients who are truly at high-risk. Of the three scores, the most accurate appears to be that based on NLR, AMC, LDH > ULN and age ≥ 65 years, which identifies 32% of high-risk patients, correlating well with what is seen in clinical practice. 相似文献
65.
Javed A. Shaik Nima Estharabadi Ronda S. Farah Maria K. Hordinsky 《Experimental dermatology》2020,29(10):1004-1011
Platelet α-granules release growth factors (GFs) that promote healing and tissue regeneration. Platelet-rich plasma (PRP) is shown to be beneficial in treating alopecia, and however, clinical response can be inconsistent. Due to several fold enrichment of platelets secreting large quantities of GFs following PRP injections, heterogeneity in amounts of GFs secreted by platelets may contribute to inconsistent clinical responses. Herein, we evaluated factors that could potentially contribute to heterogeneous secretion of GFs by platelets. We measured platelet secretion of transforming growth factor beta1 (TGFβ1), platelet-derived growth factor (PDGF-BB), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF2) in aliquots of de-identified PRP samples from female patients undergoing therapy in the hair disease clinic. Although secretion of GFs by platelets was comparable in PRP samples of patients with non-cicatricial and cicatricial alopecia, a Shapiro-Wilk test for normal distribution indicated significant variability across all patient samples. The amount of GF secreted by platelets was comparable when PRP prepared from two FDA-cleared devices with distinct techniques were compared. We provide evidence of platelets secreting heterogeneous amounts of GFs within each sample as high and low secretion of random factors could be simultaneously detected. These results suggest inherent heterogeneity in secretion of GFs by platelets in patient samples that are not influenced by the device used to prepare PRP. Since some GFs could have antagonistic effects on hair growth, a balance between amounts of growth promoting and inhibiting factors may be crucial in determining clinical response to PRP therapy. 相似文献
66.
67.
Adeline Tarantini Sylvie Huet Gérard Jarry Rachelle Lanceleur Martine Poul Ana Tavares Nádia Vital Henriqueta Louro Maria João Silva Valérie Fessard 《Environmental and molecular mutagenesis》2015,56(2):218-227
Synthetic amorphous silica (SAS) in its nanosized form is now used in food applications although the potential risks for human health have not been evaluated. In this study, genotoxicity and oxidative DNA damage of two pyrogenic (NM‐202 and 203) and two precipitated (NM‐200 and ‐201) nanosized SAS were investigated in vivo in rats following oral exposure. Male Sprague Dawley rats were exposed to 5, 10, or 20 mg/kg b.w./day for three days by gavage. DNA strand breaks and oxidative DNA damage were investigated in seven tissues (blood, bone marrow from femur, liver, spleen, kidney, duodenum, and colon) with the alkaline and the (Fpg)‐modified comet assays, respectively. Concomitantly, chromosomal damage was investigated in bone marrow and in colon with the micronucleus assay. Additionally, malondialdehyde (MDA), a lipid peroxidation marker, was measured in plasma. When required, a histopathological examination was also conducted. The results showed neither obvious DNA strand breaks nor oxidative damage with the comet assay, irrespective of the dose and the organ investigated. Similarly, no increases in chromosome damage in bone marrow or lipid peroxidation in plasma were detected. However, although the response was not dose‐dependent, a weak increase in the percentage of micronucleated cells was observed in the colon of rats treated with the two pyrogenic SAS at the lowest dose (5 mg/kg b.w./day). Additional data are required to confirm this result, considering in particular, the role of agglomeration/aggregation of SAS NMs in their uptake by intestinal cells. Environ. Mol. Mutagen. 56:218–227, 2015. © 2014 Wiley Periodicals, Inc. 相似文献
68.
Is it possible to make a diagnosis of raw,heated, and baked egg allergy in children using cutoffs? A systematic review 下载免费PDF全文
69.
Konrad Matyja Anna Małachowska-Jutsz Anna K. Mazur Kazimierz Grabas 《Ecotoxicology (London, England)》2016,25(5):924-939
Dehydrogenase activity is frequently used to assess the general condition of microorganisms in soil and activated sludge. Many studies have investigated the inhibition of dehydrogenase activity by various compounds, including heavy metal ions. However, the time after which the measurements are carried out is often chosen arbitrarily. Thus, it can be difficult to estimate how the toxic effects of compounds vary during the reaction and when the maximum of the effect would be reached. Hence, the aim of this study was to create simple and useful mathematical model describing changes in dehydrogenase activity during exposure to substances that inactivate enzymes. Our model is based on the Lagergrens pseudo-first-order equation, the rate of chemical reactions, enzyme activity, and inactivation and was created to describe short-term changes in dehydrogenase activity. The main assumption of our model is that toxic substances cause irreversible inactivation of enzyme units. The model is able to predict the maximum direct toxic effect (MDTE) and the time to reach this maximum (TMDTE). In order to validate our model, we present two examples: inactivation of dehydrogenase in microorganisms in soil and activated sludge. The model was applied successfully for cadmium and copper ions. Our results indicate that the predicted MDTE and TMDTE are more appropriate than EC50 and IC50 for toxicity assessments, except for long exposure times. 相似文献
70.
John Lennon Silva Cunha Amanda Almeida Leite Thamiris de Castro Abrantes Lorena Passoni Vervloet Thayn Melo de Lima Morais Gerson de Oliveira Paiva Neto Tatiana Nayara Librio Kimura Snia Maria Soares Ferreira Ricardo Luiz Cavalcanti de Albuquerque‐Júnior Aline Corrêa Abraho Mario Jos Romaach Bruno Augusto Benevenuto de Andrade Oslei Paes de Almeida Ciro Dantas Soares 《Journal of cutaneous pathology》2021,48(1):24-33