全文获取类型
收费全文 | 77495篇 |
免费 | 4168篇 |
国内免费 | 265篇 |
专业分类
耳鼻咽喉 | 1114篇 |
儿科学 | 2468篇 |
妇产科学 | 1564篇 |
基础医学 | 10082篇 |
口腔科学 | 3495篇 |
临床医学 | 5114篇 |
内科学 | 18645篇 |
皮肤病学 | 2256篇 |
神经病学 | 6777篇 |
特种医学 | 2044篇 |
外国民族医学 | 1篇 |
外科学 | 10432篇 |
综合类 | 421篇 |
一般理论 | 22篇 |
预防医学 | 6365篇 |
眼科学 | 1819篇 |
药学 | 5080篇 |
中国医学 | 420篇 |
肿瘤学 | 3809篇 |
出版年
2023年 | 559篇 |
2022年 | 1022篇 |
2021年 | 2477篇 |
2020年 | 1291篇 |
2019年 | 2299篇 |
2018年 | 3233篇 |
2017年 | 1961篇 |
2016年 | 1935篇 |
2015年 | 2029篇 |
2014年 | 2725篇 |
2013年 | 3745篇 |
2012年 | 5964篇 |
2011年 | 6535篇 |
2010年 | 3279篇 |
2009年 | 2456篇 |
2008年 | 4978篇 |
2007年 | 4950篇 |
2006年 | 4438篇 |
2005年 | 4330篇 |
2004年 | 4084篇 |
2003年 | 3677篇 |
2002年 | 3240篇 |
2001年 | 1927篇 |
2000年 | 2310篇 |
1999年 | 1438篇 |
1998年 | 443篇 |
1997年 | 305篇 |
1996年 | 280篇 |
1995年 | 240篇 |
1994年 | 223篇 |
1993年 | 184篇 |
1992年 | 334篇 |
1991年 | 325篇 |
1990年 | 278篇 |
1989年 | 231篇 |
1988年 | 244篇 |
1987年 | 206篇 |
1986年 | 165篇 |
1985年 | 163篇 |
1984年 | 151篇 |
1983年 | 137篇 |
1982年 | 78篇 |
1981年 | 65篇 |
1980年 | 71篇 |
1979年 | 89篇 |
1978年 | 80篇 |
1975年 | 61篇 |
1973年 | 58篇 |
1971年 | 63篇 |
1967年 | 62篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Khaled Adil Marija Popovic Fabio L. Cury Sergio L. Faria Marie Duclos Luis Souhami 《Practical radiation oncology》2019,9(1):24-28
Purpose
This study aimed to investigate 3 planning target volume (PTV) margin expansions and determine the most appropriate volume to be used in bladder preservation therapy when using daily cone beam computed tomography (CBCT). We aimed to establish whether a smaller PTV expansion is feasible without risking geographical miss.Methods and materials
The study included patients with bladder cancer who were treated with a hypofractionated course of radiation therapy delivered with intensity modulated radiation therapy. The clinical target volume (CTV) was the whole empty bladder, and the PTV consisted of a 1.5-cm margin around the bladder (PTV1.5 cm). Patients underwent daily CBCT imaging before treatment to assess the bladder volume and ensure accurate positioning. We investigated 2 additional smaller PTV margin expansions to determine the most appropriate volume to be used with CBCT as a daily image guided radiation therapy modality. These margins were created retrospectively on every CBCT. The first additional volume was a uniform PTV margin of the surrounding 1 cm (PTV1 cm). When considering that the majority of the internal bladder movement was due to the variation in filling that occurs in the superior and anterior directions, a second volume of an anisotropic PTV margin with a 1.5-cm superior/anterior and 1 cm in other directions (PTV1/1.5 cm) was created. We recorded the frequency and measured the volume of bladder falling out of each PTV based on the daily CBCT.Results
For the purpose of this study, we considered an arbitrary 5 cm3 of CTV falling out of the designated PTV as a clinically significant volumetric miss. The frequency of such a miss when applying the uniform PTV1 cm was 1%. However, when applying the uniform PTV1.5 cm and anisotropic PTV1/1.5 cm margins, the frequency was 0.5% and 0.5%, respectively.Conclusions
The anisotropic PTV expansion of 1.5 cm superiorly and anteriorly and 1 cm in all other directions around the bladder (CTV) provides a safe PTV approach when daily CBCT imaging is used to localize an empty bladder. 相似文献22.
Iclea Rocha Gama Euclides Marinho Trindade-Filho Suzana Lima Oliveira Nassib Bezerra Bueno Isabelle Tenório Melo Cyro Rego Cabral-Junior Elenita M. Barros Jaqueline A. Galvão Wanessa S. Pereira Raphaela C. Ferreira Bruna R. Domingos Terezinha da Rocha Ataide 《Metabolic brain disease》2015,30(1):93-98
23.
Maria Gonzalez-Cao Cristina Carrera Juan Francisco Rodriguez Moreno Pedro Rodríguez-Jiménez Mónica Antoñanzas Basa Rosa Feltes Ochoa Teresa Puertolas Eva Muñoz-Couselo José Luis Manzano Ivan Marquez-Rodas Juan Martín-Liberal Ainara Soria Pilar Lopez Criado Almudena Garcia-Castaño Aram Boada Pablo Ayala de Miguel Susana Puig Guillermo Crespo Alfonso Berrocal 《Journal of the American Academy of Dermatology》2021,84(5):1412-1415
24.
25.
26.
27.
Caio Henrique de Carvalho Assuno Júlio Csar Trabanco Raquel Fornaziero Gomes Renata Rodrigues Moreira Alessandra Giannella Samelli 《La Medicina del lavoro》2019,110(4):304
Objective:The present study evaluates a training program for fitting different hearing protection devices (HPDs) based on personal attenuation rating (PAR) before, immediately after, and six months after training.Methods:A total of 67 workers from a public university in the city of São Paulo, Brazil, were invited to participate in the measurement of PARs for foam and silicone protectors through the 3M™ E-A-Rfit Validation System. Two evaluations were performed for each protector at each sampling date: one after reading printed material (the package instructions) and another after being trained by an audiologist. The same procedures were repeated after six months. The final sample consisted of 30 individuals. ANOVA was used for statistical analysis.Results:Larger PAR values were observed after training by the audiologist, and smaller values were observed after six months. Then, after re-training, the values increased again. There were no statistically significant differences in PAR among the HPDs tested. Even after the two training sessions, 23 to 27% of the subjects did not obtain adequate PAR values.Conclusion:These findings emphasize the need for continual worker training in the correct fit of earplug HPDs and the importance of longitudinal PAR monitoring. In addition, some workers, despite the training provided, did not adapt to the HPDs used. Therefore, it is essential that other protection methods and/or other HPD types are made available to these individuals.Key words: Hearing, noise-induced hearing loss, occupational health, personal protective equipment, hearing protection devices 相似文献
28.
29.
Lorena Martin-Morales Sara Manzano Maria Rodrigo-Faus Adrian Vicente-Barrueco Victor Lorca Gonzalo Núñez-Moreno Paloma Bragado Almudena Porras Trinidad Caldes Pilar Garre Alvaro Gutierrez-Uzquiza 《International journal of cancer. Journal international du cancer》2023,152(2):283-297
Matrix metalloproteinase-11 (MMP11) is an enzyme with proteolytic activity against matrix and nonmatrix proteins. Although most MMPs are secreted as inactive proenzymes and are later activated extracellularly, MMP11 is activated intracellularly by furin within the constitutive secretory pathway. It is a key factor in physiological tissue remodeling and its alteration may play an important role in the progression of epithelial malignancies and other diseases. TCGA colon and colorectal adenocarcinoma data showed that upregulation of MMP11 expression correlates with tumorigenesis and malignancy. Here, we provide evidence that a germline variant in the MMP11 gene (NM_005940: c.232C>T; p.(Pro78Ser)), identified by whole exome sequencing, can increase the tumorigenic properties of colorectal cancer (CRC) cells. P78S is located in the prodomain region, which is responsible for blocking MMP11's protease activity. This variant was detected in the proband and all the cancer-affected family members analyzed, while it was not detected in healthy relatives. In silico analyses predict that P78S could have an impact on the activation of the enzyme. Furthermore, our in vitro analyses show that the expression of P78S in HCT116 cells increases tumor cell invasion and proliferation. In summary, our results show that this variant could modify the structure of the MMP11 prodomain, producing a premature or uncontrolled activation of the enzyme that may contribute to an early CRC onset in these patients. The study of this gene in other CRC cases will provide further information about its role in CRC development, which might improve patient treatment in the future. 相似文献
30.