全文获取类型
收费全文 | 19201篇 |
免费 | 1672篇 |
国内免费 | 1386篇 |
专业分类
耳鼻咽喉 | 185篇 |
儿科学 | 146篇 |
妇产科学 | 246篇 |
基础医学 | 2267篇 |
口腔科学 | 213篇 |
临床医学 | 2289篇 |
内科学 | 3384篇 |
皮肤病学 | 189篇 |
神经病学 | 926篇 |
特种医学 | 738篇 |
外国民族医学 | 11篇 |
外科学 | 2045篇 |
综合类 | 3166篇 |
一般理论 | 2篇 |
预防医学 | 1097篇 |
眼科学 | 566篇 |
药学 | 2026篇 |
15篇 | |
中国医学 | 961篇 |
肿瘤学 | 1787篇 |
出版年
2024年 | 63篇 |
2023年 | 317篇 |
2022年 | 744篇 |
2021年 | 958篇 |
2020年 | 673篇 |
2019年 | 652篇 |
2018年 | 725篇 |
2017年 | 572篇 |
2016年 | 607篇 |
2015年 | 855篇 |
2014年 | 1049篇 |
2013年 | 868篇 |
2012年 | 1383篇 |
2011年 | 1517篇 |
2010年 | 864篇 |
2009年 | 724篇 |
2008年 | 1047篇 |
2007年 | 1006篇 |
2006年 | 976篇 |
2005年 | 955篇 |
2004年 | 641篇 |
2003年 | 591篇 |
2002年 | 516篇 |
2001年 | 460篇 |
2000年 | 512篇 |
1999年 | 455篇 |
1998年 | 343篇 |
1997年 | 303篇 |
1996年 | 269篇 |
1995年 | 258篇 |
1994年 | 170篇 |
1993年 | 125篇 |
1992年 | 166篇 |
1991年 | 158篇 |
1990年 | 127篇 |
1989年 | 123篇 |
1988年 | 112篇 |
1987年 | 99篇 |
1986年 | 95篇 |
1985年 | 61篇 |
1984年 | 29篇 |
1983年 | 23篇 |
1982年 | 11篇 |
1981年 | 17篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1974年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
醒脑静注射液对脑缺血再灌注氧化损伤的实验研究 总被引:11,自引:0,他引:11
[目的]研究中药醒脑静注射液对沙土鼠急性脑缺血再灌注损伤的作用。[方法]采用沙土鼠双侧颈总动脉夹闭制作沙土鼠急性全脑缺血模型,观察干预性腹腔注射西药尼莫地平和中药醒脑静注射液对缺血再灌注急性期沙土鼠脑组织中MDA含量和SOD活力的影响。[结果]西药尼莫地平和醒脑静注射液均能显著提高脑缺血再灌注后SOD活力和降低MDA含量,醒脑静注射液疗效和西药尼莫地平无显著差异,而醒脑静大中小剂量组之间有较显著的差异,疗效随剂量的增加而增大。[结论]醒脑静注射液作为抗自由基损伤的中药和西药尼莫地平有相当的疗效。 相似文献
52.
The association of XRCC1 haplotypes and chromosomal damage levels in peripheral blood lymphocyte among coke-oven workers. 总被引:1,自引:0,他引:1
Shuguang Leng Juan Cheng Linyuan Zhang Yong Niu Yufei Dai Zufei Pan Bin Li Fengsheng He Yuxin Zheng 《Cancer epidemiology, biomarkers & prevention》2005,14(5):1295-1301
Theoretically, a haplotype has a higher level of heterozygosity than individual single nucleotide polymorphism (SNP) and the association study based on the haplotype may have an increased power for detecting disease associations compared with SNP-based analysis. In this study, we investigated the effects of four haplotype-tagging SNPs (htSNP) and the inferred haplotype pairs of the X-ray cross-complementing group 1 (XRCC1) gene on chromosome damage detected by the cytokinesis-block micronucleus assay. The study included 141 coke-oven workers with exposure to a high level of polycyclic aromatic hydrocarbons and 66 nonexposed controls. The frequencies of total MN and MNed cells were borderline associated with the Arg(194)Trp polymorphism (P = 0.053 and P = 0.050, respectively) but not associated with the Arg(280)His, Arg(399)Gln and Gln(632)Gln polymorphisms among coke-oven workers. Five haplotypes, including CGGG, TGGG, CAGG, CGAG, and CGGA, were inferred based on the four htSNPs of XRCC1 gene. The haplotype CGGG was associated with the decreased frequencies of total MN and MNed cells, and the haplotypes TGGG and CGAG were associated with the increased frequencies of total MN and MNed cells with adjustment for covariates among coke-oven workers. This study showed that the haplotypes derived from htSNPs in the XRCC1 gene were more likely than single SNPs to correlate with the polycyclic aromatic hydrocarbon-induced chromosome damage among coke-oven workers. 相似文献
53.
54.
Diabetic retinopathy (DR) is one of the leading causes of vision loss and can be effectively avoided by screening, early diagnosis and treatment. In order to increase the universality and efficiency of DR screening, many efforts have been invested in developing intelligent screening, and there have been great advances. In this paper, we survey DR screening from four perspectives: 1) public color fundus image datasets of DR; 2) DR classification and related lesion-extraction approaches; 3) existing computer-aided systems for DR screening; and 4) existing issues, challenges, and research trends. Our goal is to provide insights for future research directions on DR intelligent screening. 相似文献
55.
It has previously been reported that propofol regulates the development of human osteosarcoma (OS). However, the specific molecular mechanisms underlying the effect of propofol on OS remain poorly understood. Therefore, the aim of the present study was to explore the effects of propofol on OS U2OS cells and the potential underlying mechanism. The Cell Counting Kit-8 and colony formation assays were performed to assess cell viability and proliferation. Furthermore, cell apoptosis was assessed using the TUNEL assay and western blotting. Wound healing and Transwell assays were performed to evaluate OS cell migration and invasion abilities, respectively. The protein expression levels of epithelial-mesenchymal transition (EMT)-, autophagy- and adenosine monophosphate-activated protein kinase (AMPK)/FOXO1 signaling pathway-related proteins were also determined using western blotting. The results demonstrated that propofol significantly reduced the viability of OS cells and promoted autophagy in a dose-dependent manner. Moreover, cell treatment with propofol significantly enhanced the protein expression levels of phosphorylated (p)-AMPK and FOXO1, while decreasing the protein levels of p-FOXO1. Furthermore, treatment with propofol significantly suppressed cell viability, migration and invasion abilities and the EMT of OS cells, and potentially promoted cell apoptosis via inducing autophagy via the AMPK/FOXO1 signaling pathway. In summary, the present study indicated that propofol potentially had an inhibitory effect on the development of OS cells via AMPK/FOXO1-mediated autophagy. These results have therefore provided an experimental basis for further studies into the therapeutic effect of propofol on OS. 相似文献
56.
Robotic milling has broad application prospects in many processing fields. However, the milling performance of a robot in a certain posture, such as in face milling or grooving tasks, is extremely sensitive to process parameters due to the influence of the serial structure of the robot system. Improper process parameters are prone to produce machining defects such as low surface quality. These deficiencies substantially decrease the further application development of robotic milling. Therefore, this paper selected a certain posture and carried out the robotic flat-end milling experiments on a 7075-T651 high-strength aeronautical aluminum alloy under dry conditions. Milling load, surface quality and vibration were selected to assess the influence of process parameters like milling depth, spindle speed and feed rate on the milling performance. Most notably, the contribution ratio based on the analysis of variance (ANOVA) was introduced to statistically investigate the relation between parameters and milling performance. The obtained results show that milling depth is highly significant in milling load, which had a contribution ratio of 69.25%. Milling depth is also highly significant in vibration, which had a contribution ratio of 51.41% in the X direction, 41.42% in the Y direction and 75.97% in the Z direction. Moreover, the spindle speed is highly significant in surface roughness, which had a contribution ratio of 48.02%. This present study aims to quantitatively evaluate the influence of key process parameters on robotic milling performance, which helps to select reasonable milling parameters and improve the milling performance of the robot system. It is beneficial to give full play to the advantages of robots and present more possibilities of robot applications in machining and manufacturing. 相似文献
57.
Jing Zhao Kaixin Ding Manting Hou Yuanhua Li Xiaorong Hou Wenzhang Dai Zhiyong Li Jun Zhao Wenlong Liu Zhaofang Bai 《Pharmaceutical biology》2022,60(1):958
ContextSchisandra chinensis (Turcz.) Baill. (Magnoliaceae) essential oil (SCEO) composition is rich in lignans that are believed to perform protective effects in the liver.ObjectiveThis study investigates the effects of SCEO in the treatment of acetaminophen (APAP)-induced liver injury in mice.Materials and methodsC57BL/6 mice (n = 56) were randomly divided into seven groups: normal; APAP (300 mg/kg); APAP plus bicyclol (200 mg/kg); APAP plus SCEO (0.25, 0.5, 1, 2 g/kg). Serum biochemical parameters for liver function, inflammatory factors, and antioxidant activities were determined. The protein expression levels of Nrf2, GCLC, GCLM, HO-1, p62, and LC3 were assessed by western blotting. Nrf2, GCLC, HO-1, p62, and LC3 mRNA were detected by real-time PCR.ResultsCompared to APAP overdose, SCEO (2 g/kg) pre-treatment reduced the serum levels of AST (79.4%), ALT (84.6%), TNF-α (57.3%), and IL-6 (53.0%). In addition, SCEO (2 g/kg) markedly suppressed cytochrome P450 2E1 (CYP2E1) (15.4%) and attenuated the exhaustion of GSH (43.6%) and SOD (16.8%), and the accumulation of MDA (22.6%) in the liver, to inhibit the occurrence of oxidative stress. Moreover, hepatic tissues from our experiment revealed that SCEO pre-treatment mitigated liver injury caused by oxidative stress by increasing Nrf2, HO-1, and GCL. Additionally, SCEO activated autophagy, which upregulated hepatic LC3-II and decreased p62 in APAP overdose mice (p < 0.05).Discussion and conclusionsOur evidence demonstrated that SCEO protects hepatocytes from APAP-induced liver injury in vivo and the findings will provide a reliable theoretical basis for developing novel therapeutics. 相似文献
58.
望面色是望诊的主要内容之一,为了加强学生望面色这一诊断方法的学习效果,在征得学生同意,自愿参加的前提下,在学生中找典型面色进行真实案例教学,调动了学生学习积极性,取得了良好教学效果,实现了教学相长。 相似文献
59.
Zhang Xu Jung-Hyun Choi David L. Dai Jun Luo Reese Jalal Ladak Qian Li Yimeng Wang Christine Zhang Shane Wiebe Alex C. H. Liu Xiaozhuo Ran Jiaqi Yang Parisa Naeli Aitor Garzia Lele Zhou Niaz Mahmood Qiyun Deng Mohamed Elaish Rongtuan Lin Lara K. Mahal Tom C. Hobman Jerry Pelletier Tommy Alain Silvia M. Vidal Thomas Duchaine Mohammad T. Mazhab-Jafari Xiaojuan Mao Seyed Mehdi Jafarnejad Nahum Sonenberg 《Proceedings of the National Academy of Sciences of the United States of America》2022,119(32)
60.