全文获取类型
收费全文 | 310700篇 |
免费 | 27321篇 |
国内免费 | 13649篇 |
专业分类
耳鼻咽喉 | 2752篇 |
儿科学 | 6717篇 |
妇产科学 | 5236篇 |
基础医学 | 48938篇 |
口腔科学 | 6246篇 |
临床医学 | 24621篇 |
内科学 | 48143篇 |
皮肤病学 | 4388篇 |
神经病学 | 28420篇 |
特种医学 | 6705篇 |
外国民族医学 | 99篇 |
外科学 | 22519篇 |
综合类 | 46693篇 |
现状与发展 | 51篇 |
一般理论 | 7篇 |
预防医学 | 14529篇 |
眼科学 | 5114篇 |
药学 | 40061篇 |
62篇 | |
中国医学 | 11314篇 |
肿瘤学 | 29055篇 |
出版年
2024年 | 265篇 |
2023年 | 4838篇 |
2022年 | 6673篇 |
2021年 | 12596篇 |
2020年 | 11006篇 |
2019年 | 9663篇 |
2018年 | 9355篇 |
2017年 | 9792篇 |
2016年 | 10071篇 |
2015年 | 11374篇 |
2014年 | 17904篇 |
2013年 | 21079篇 |
2012年 | 17813篇 |
2011年 | 20946篇 |
2010年 | 17352篇 |
2009年 | 17576篇 |
2008年 | 17672篇 |
2007年 | 17189篇 |
2006年 | 15603篇 |
2005年 | 14027篇 |
2004年 | 11943篇 |
2003年 | 10577篇 |
2002年 | 8702篇 |
2001年 | 7448篇 |
2000年 | 6265篇 |
1999年 | 5247篇 |
1998年 | 4272篇 |
1997年 | 3907篇 |
1996年 | 3290篇 |
1995年 | 3319篇 |
1994年 | 2948篇 |
1993年 | 2435篇 |
1992年 | 2109篇 |
1991年 | 1899篇 |
1990年 | 1644篇 |
1989年 | 1356篇 |
1988年 | 1175篇 |
1987年 | 1018篇 |
1986年 | 920篇 |
1985年 | 1431篇 |
1984年 | 1297篇 |
1983年 | 914篇 |
1982年 | 978篇 |
1981年 | 783篇 |
1980年 | 667篇 |
1979年 | 550篇 |
1978年 | 396篇 |
1977年 | 326篇 |
1976年 | 314篇 |
1975年 | 202篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
61.
《Clinical breast cancer》2022,22(6):507-514
Breast cancer (BC) is a highly metastatic, pathological cancer that significantly affects women worldwide. The mortality rate of BC is related to its heterogeneity, aggressive phenotype, and metastasis. Recent studies have highlighted that the tumor microenvironment (TME) is critical for the interplay between metastasis mediators in BC. BC stem cells, tumor-derived exosomes, circulatory tumor cells (CTCs), and signaling pathways dynamically remodel the TME and promote metastasis. This review examines the cellular and molecular mechanisms governing the epithelial to mesenchymal transition (EMT) that facilitate metastasis. This review also discusses the role of cancer stem cells (CSCs), tumor-derived exosomes, and CTs in promoting BC metastasis. Furthermore, the review emphasizes major signaling pathways that mediate metastasis in BC. Finally, the interplay among CSCs, exosomes, and CTCs in mediating metastasis have been highlighted. Therefore, understanding the molecular cues that mediate the association of CSCs, exosomes, and CTCs in TME helps to optimize systemic therapy to target metastatic BC. 相似文献
62.
63.
Matthew C. Phillips Laura Sarff Josh Banerjee Chase Coffey Paul Holtom Steve Meurer Noah Wald-Dickler Brad Spellberg 《Journal of medical virology》2022,94(1):318-326
When hospitals first encountered coronavirus disease 2019 (COVID-19), there was a dearth of therapeutic options and nearly 1 in 3 patients died from the disease. By the summer of 2020, as deaths from the disease declined nationally, multiple single-center studies began to report declining mortality of patients with COVID-19. To evaluate the effect of COVID-19 on hospital-based mortality, we searched the Vizient Clinical Data Base for outcomes data from approximately 600 participating hospitals, including 130 academic medical centers, from January 2017 through December 2020. More than 32 million hospital admissions were included in the analysis. After an initial spike, mortality from COVID-19 declined in all regions of the country to under 10% by June 2020 and remained constant for the remainder of the year. Despite this, inpatient, all-cause mortality has increased since the beginning of the pandemic, even those without respiratory failure. Inpatient mortality has particularly increased in elderly patients and in those requiring intubation for respiratory failure. Since June 2020, COVID-19 kills one in every 10 patients admitted to the hospital with this diagnosis. The addition of this new disease has raised overall hospital mortality especially those who require intubation for respiratory failure. 相似文献
64.
65.
《Mayo Clinic proceedings. Mayo Clinic》2022,97(7):1282-1293
ObjectiveTo assess the association between adherence to a Mediterranean lifestyle and changes in pain, and its characteristics over time in older adults.Patients and MethodsWe analyzed data from 864 and 862 community-dwelling individuals aged 65+ years from the Study on Cardiovascular Health, Nutrition and Frailty in Older Adults in Spain (Seniors-ENRICA) Seniors-ENRICA-1 (2008–2010 to 2012) and Seniors-ENRICA-2 (2015–2017 to 2019) cohorts, with a median follow-up of 2.8 and 2.4 years, respectively. Adherence to a Mediterranean lifestyle was assessed at baseline with the 27-item Mediterranean lifestyle (MEDLIFE) index. Pain changes over time were calculated with a pain scale that assessed the frequency, severity, and the number of pain locations both at baseline and follow-up. Multivariable-adjusted relative risk ratios (RRRs) were obtained using multinomial logistic regression.ResultsIn the pooled cohorts, after a median follow-up of 2.6 years, pain worsened for 697 participants, improved for 734, and did not change for 295. Compared with the lowest category of MEDLIFE adherence, those in the highest category showed an RRR of improvement vs worsening of overall pain of 1.85 (95% CI, 1.28 to 2.67; P-trend<.001). MEDLIFE adherence was also linked to improvement in pain frequency (RRR, 1.98; 95% CI, 1.31 to 3.01; P-trend=.001), pain severity (RRR, 2.00; 95% CI, 1.33 to 3.00; P-trend=.001), and a reduction in the number of pain locations (RRR, 1.68; 95% CI, 1.13 to 2.50; P-trend=.004). Limitations of this study are the use of self-reported lifestyle data.ConclusionA Mediterranean lifestyle was associated with improvement of pain characteristics in older adults. Experimental studies should assess the efficacy of an integral lifestyle approach for the management of pain in older adults. 相似文献
66.
67.
68.
《Journal of infection and chemotherapy》2022,28(12):1639-1644
IntroductionSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) first broke out in Wuhan in December 2019, and has since caused a global pandemic. The efficacy of several drugs has been evaluated, and it is now evident that tocilizumab has a beneficial effect, especially combined with corticosteroids, in patients with Coronavirus Disease 2019 (COVID-19). However, the optimal timing of tocilizumab administration has not yet been established. The goal of the present study was to determine the optimal timing of tocilizumab administration after starting corticosteroid therapy in patients with COVID-19.MethodsWe retrospectively analyzed the clinical characteristics of patients who were hospitalized for COVID-19 and treated with tocilizumab and corticosteroids in our hospital. The patients were divided into concurrent and sequential groups. The concurrent group received tocilizumab ≤24 h after corticosteroids, and the sequential group received tocilizumab >24 h after corticosteroid administration.ResultsThe baseline clinical characteristics of tocilizumab administration were similar between the two groups. White blood cell counts were significantly lower and C-reactive protein levels were significantly higher in the concurrent group than the sequential group. In the concurrent group, tocilizumab administration led to a significant decrease in maximum body temperature. In addition, there were significantly more oxygen-free days in the concurrent group than in the sequential group. However, survival rate was not significantly different between the concurrent and the sequential groups.ConclusionsIn the combination therapy with tocilizumab and corticosteroids, early administration of tocilizumab after starting corticosteroid treatment is effective when treating COVID-19. 相似文献
69.
目的 鉴定与丹参酮合成相关转录因子AP2/ERF家族中SmERF108转录因子,并分析转录因子SmERF108的靶基因。方法 利用生物信息学在线分析平台如NCBI、PFAM等分析SmERF108的序列特征;MEGA-X软件用于构建SmERF108与不同功能转录因子的系统进化树;拟南芥原生质体转化法鉴定SmERF108蛋白的亚细胞定位;通过实时荧光定量PCR(Real-time qPCR)对SmERF108基因在丹参不同器官和组织差异表达进行检测;利用酵母体系对SmERF108的转录激活活性进行探究并用酵母单杂技术确定其靶基因。结果 SmERF108具有典型的AP2/ERF保守结构域,属于ERF-B3亚组,系统进化树和保守基序分析显示SmERF108与丹参中SmERF128、青蒿中AaERF2亲缘关系较近且保守基序分布一致;亚细胞定位显示SmERF108蛋白定位于细胞核;SmERF108基因在周皮中表达最高,且呈现周皮(R1)>韧皮部(R2)>木质部(R3)的规律;酵母自激活验证SmERF108具有转录激活活性,同时酵母单杂交确认其能与关键酶基因SmCPS1启动子结合。结论 鉴定到丹参中一个新转录因子SmERF108,生物信息学分析及差异表达分析预测与丹参酮合成相关,分子互作初步证实靶基因为SmCPS1二萜环化酶。 相似文献
70.
目的 银椴苷(Tiliroside,Tle)是一种天然产物,存在于结香花(Edgeworthia chrysantha Lindl.)、金英(Galphimia gracilis)、和Phlomoides spectabilis等生物体中。本文主要探讨Tle对脂多糖(lipopolysaccharide,LPS)激活的原代小胶质细胞的M1/M2极化的转化作用及其抑制神经炎症反应的影响。方法 MTT检测各浓度Tle对LPS激活的原代小胶质细胞活性的影响;Griess试剂检测LPS激活的原代小胶质细胞的一氧化氮(Nitric oxide,NO)产物生成量的影响;ELISA法检测Tle对LPS激活的原代小胶质细胞的肿瘤坏死因子-α(Tumor necrosis factor-α,TNF-α)、白细胞介素-6(Interleukin-6,IL-6)蛋白水平的影响;qRT-PCR检测Tle对LPS激活的原代小胶质细胞的精氨酸酶-1(Arginase-1,Arg-1)和胰岛素生长因子-1(Insulin growth factor-1,IGF-1)的mRNA表达水平。结果 Tle(0-80 μmol·L-1)对LPS激活的原代小胶质细胞活性没有明显影响;Tle显著降低LPS激活的原代小胶质细胞亚硝酸盐的含量,并对炎症因子IL-6、TNF-α蛋白水平有显著抑制作用,同时显著提高抗炎因子Arg-1和IGF-1的mRNA水平。结论 Tle能够通过促进LPS激活的原代小胶质细胞M1型向M2型转化从而抑制神经炎症反应,因此Tle具有一定的神经保护作用。 相似文献