首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   139628篇
  免费   11158篇
  国内免费   7585篇
耳鼻咽喉   745篇
儿科学   3177篇
妇产科学   1597篇
基础医学   23665篇
口腔科学   2904篇
临床医学   12075篇
内科学   22400篇
皮肤病学   1912篇
神经病学   11205篇
特种医学   2573篇
外国民族医学   43篇
外科学   8430篇
综合类   26386篇
现状与发展   40篇
一般理论   1篇
预防医学   8012篇
眼科学   1967篇
药学   14794篇
  14篇
中国医学   3941篇
肿瘤学   12490篇
  2024年   98篇
  2023年   1417篇
  2022年   2401篇
  2021年   4443篇
  2020年   4001篇
  2019年   3569篇
  2018年   3469篇
  2017年   3957篇
  2016年   4549篇
  2015年   4990篇
  2014年   8015篇
  2013年   9705篇
  2012年   8565篇
  2011年   9920篇
  2010年   7956篇
  2009年   7871篇
  2008年   8265篇
  2007年   8441篇
  2006年   7794篇
  2005年   7288篇
  2004年   6246篇
  2003年   5415篇
  2002年   4443篇
  2001年   3959篇
  2000年   3373篇
  1999年   2757篇
  1998年   2298篇
  1997年   1929篇
  1996年   1523篇
  1995年   1461篇
  1994年   1241篇
  1993年   953篇
  1992年   796篇
  1991年   702篇
  1990年   612篇
  1989年   460篇
  1988年   404篇
  1987年   369篇
  1986年   321篇
  1985年   455篇
  1984年   385篇
  1983年   248篇
  1982年   298篇
  1981年   236篇
  1980年   197篇
  1979年   128篇
  1978年   104篇
  1977年   88篇
  1976年   76篇
  1975年   62篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.

Background

Rosacea is a chronic inflammatory skin condition whose etiology has been linked to mast cells and the antimicrobial peptide cathelicidin LL-37. Individuals with refractory disease have demonstrated clinical benefit with periodic injections of onabotulinum toxin, but the mechanism of action is unknown.

Objectives

To investigate the molecular mechanism by which botulinum toxin improves rosacea lesions.

Methods

Primary human and murine mast cells were pretreated with onabotulinum toxin A or B or control. Mast cell degranulation was evaluated by β-hexosaminidase activity. Expression of botulinum toxin receptor Sv2 was measured by qPCR. The presence of SNAP-25 and VAMP2 was established by immunofluorescence. In vivo rosacea model was established by intradermally injecting LL-37 with or without onabotulinum toxin A pretreatment. Mast cell degranulation was assessed in vivo by histologic counts. Rosacea biomarkers were analyzed by qPCR of mouse skin sections.

Results

Onabotulinum toxin A and B inhibited compound 48/80-induced degranulation of both human and murine mast cells. Expression of Sv2 was established in mouse mast cells. Onabotulinum toxin A and B increased cleaved SNAP-25 and decreased VAMP2 staining in mast cells respectively. In mice, injection of onabotulinum toxin A significantly reduced LL-37-induced skin erythema, mast cell degranulation, and mRNA expression of rosacea biomarkers.

Conclusions

These findings suggest that onabotulinum toxin reduces rosacea-associated skin inflammation by directly inhibiting mast cell degranulation. Periodic applications of onabotulinum toxin may be an effective therapy for refractory rosacea and deserves further study.  相似文献   
82.
83.

Background

Glucocorticoids play essential roles in the treatment of childhood acute lymphoblastic leukaemia (ALL); however, treatment with these agents can result in severe side-effects. This study, the first of its kind in a Saudi population, investigates associations of ABCB1 gene polymorphisms (pharmacodynamics and pharmacokinetic) with the development of toxicity and side effects (glucose abnormality, liver toxicity and infection) in a small population of Saudi children with ALL.

Methods

Three single nucleotide polymorphisms (SNPs) of the ABCB1 gene (rs 3213619 T129C, rs 2032582 G2677T and rs1045642 C3435T) were analysed in 70 Saudi children with ALL and 60 control subjects. Participants were treated according to the ALL 2000 study protocol. Toxicities were assessed and associations with genotypes were evaluated according to Common Toxicity Criteria (NCI-CTC).

Results

Significant associations were observed among carriers and the mutated genotype C3435T (ABCB1), which had an incidence of infection (p?=?0.05). Although no correlations were found between liver toxicity and glucose abnormalities for patients carrying ABCB1 SNPs, risk factors for liver toxicity were elevated by a factor of three for patients carrying the SNP G2677T, OR 3.00 (1.034–8.702). The risk factor of glucose abnormality toxicity for the patients carring T129C were increased three times OR 3.06 (0.486–19.198).

Conclusions

In terms of infection incidence, polymorphism C3435T may contribute to potential life-threatening infections during paediatric ALL therapy, through glucocorticoid usage.  相似文献   
84.
Objectives: Optic neuritis (ON) is defined as inflammation of the optic nerve, which is mostly idiopathic. However, it can be associated with various causes (demyelinating lesions, autoimmune disorders, infectious and inflammatory conditions). Inflammatory demyelinating disorder of the optic nerve can be associated with multiple sclerosis. It is thought that CETP, SIRT1, FGFR2, STAT3, VEGFA and IL6 genes play a key role in this autoimmune inflammatory disease. The aim of our study was to determine if the frequency of the CETP, SIRT1, FGFR2, STAT3, VEGFA and IL6 gene polymorphisms have an influence on the development of acute ON.

Methods: The study enrolled patients with ON and a random sample of healthy population. The genotyping test of the CETPrs5882,rs708272, SIRT1rs12778366, FGFR2rs2981582, STAT3rs744166, VEGFArs833068, IL6rs1800795 polymorphisms was carried out using the RT-PCR method.

Results: Our study determined that the G/A genotype of CETPrs708272 was associated with two-fold-decreased odds of ON development under the codominant (OR = 0.495;95%CI:0.256–0.959) and overdominant (OR = 0.501;95%CI:0.280–0.895) models. Also, each allele C at VEGFArs833068 was associated with 1.7-fold increased odds of ON development under the additive model (OR = 1.733;95%CI:1.148–2.615). Furthermore, IL6 rs1800795 G/G genotype was associated with increased odds of ON development under the codominant (OR = 2.869;95%CI:1.280–6.434) and recessive (OR = 2.315;95%CI:1.251–4.285) models.

Conclusions: We revealed that the genotypes of CETPrs708272 G/A, IL6rs1800795 G/G, and each allele C at VEGFArs833068 were associated with ON. CETPrs708272 G/G genotype was associated with decreased by 62% odds of ON with MS development under the recessive (OR = 0.379;95%CI:0.155–0.929; p = .034) model.  相似文献   

85.
《Vaccine》2019,37(31):4382-4391
Cancer-associated fibroblasts (CAFs), major components of the tumor microenvironment (TME), promote tumor growth and metastasis and inhibit the anti-tumor immune response. We previously constructed a DNA vaccine expressing human FAPα, which is highly expressed by CAFs, to target these cells in the TME, and observed limited anti-tumor effects in the 4T1 breast cancer model. When the treatment time was delayed until tumor nodes formed, the anti-tumor effect of the vaccine completely disappeared. In this study, to improve the safety and efficacy, we constructed a new FAPα-targeted vaccine containing only the extracellular domain of human FAPα with a tissue plasminogen activator signal sequence for enhanced antigen secretion and immunogenicity. The number of CAFs was more effectively reduced by CD8+ T cells induced by the new vaccine. This resulted in decreases in CCL2 and CXCL12 expression, leading to a significant decrease in the ratio of myeloid-derived suppressor cells in the TME. Moreover, when mice were treated after the establishment of tumors, the vaccine could still delay tumor growth. To facilitate the future application of the vaccine in clinical trials, we further optimized the gene codons and reduced the homology between the vaccine and the original sequence, which may be convenient for evaluating the vaccine distribution in the human body. These results indicated that the new FAPα-targeted vaccine expressing an optimized secreted human FAPα induced enhanced anti-tumor activity by reducing the number of FAPα+ CAFs and enhancing the recruitment of effector T cells in the 4T1 tumor model mice.  相似文献   
86.
《Vaccine》2019,37(24):3234-3240
Leucine aminopeptidase (FhLAP) and cathepsin L1 (FhCL1) of Fasciola hepatica play a critical role in parasite feeding, migration through host tissue, and immune evasion. These antigens have been tested for immune protection as single components with variable degrees of success. The chimeric-protein approach could improve protection levels against fasciolosis. Previously, we reported the design and construction of a chimeric protein composed of antigenic sequences of FhLAP and FhCL1 of F. hepatica. The goal of the present study was to express and evaluate the immune-protective capacity of this chimeric protein (rFhLAP-CL1) in sheep. Animals were randomly allocated into five groups with five animals in each group. Groups 1, 2 and 3 were immunized twice with 100 μg, 200 μg and 400 μg of rFhLAP-CL1 emulsified with Quil A adjuvant, whereas groups 4 and 5 were the adjuvant control and infection control groups, respectively. The animals were then challenged with 200 metacercariae two weeks after the rFhLAP-CL1 booster. The fluke burden was reduced by 25.5%, 30.7% (p < 0.05) and 46.5% (p < 0.01) in sheep immunized with 100 μg, 200 μg and 400 μg of chimeric protein, respectively, in comparison to the infection control group. There was a reduction of 22.7% (p < 0.05) and 24.4% (p < 0.01) in fecal egg count in groups 2 and 3, respectively, compared to the infection control group. Sheep immunized with chimeric protein produced F. hepatica excretion-secretion product-specific total IgG antibody, which were increased after challenge. Moreover, the levels of rFhLAP-CL1-specific IgG1 and IgG2 isotypes in immunized sheep increased rapidly two weeks after the first immunization and were significantly more elevated than those of the control groups, indicating a mixed Th1/Th2 response. This is a preliminary evaluation of the chimeric protein rFhLAP-CL1 as a possible immunogen against F. hepatica infection in sheep.  相似文献   
87.

Objective

To assay peripheral inter-ictal cytokine serum levels and possible relations with non-invasive vagus nerve stimulation (nVNS) responsiveness in migraineurs.

Methods

This double-blinded, sham-controlled study enrolled 48 subjects and measured headache severity, frequency [headache days/month, number of total and mild/moderate/severe classified attacks/month], functional state [sleep, mood, body weight, migraine-associated disability] and serum levels of inflammatory markers [inter-ictal] using enzyme-linked immunoassays at baseline and after 2 months of adjunctive nVNS compared to sham stimulation and suitably matched controls.

Results

No significant differences were observed at baseline and after 2 months for headache severity, total attacks/month, headache days/month and functional outcome [sleep, mood, disability] between verum and sham nVNS. However, the number of severe attacks/month significantly decreased in the verum nVNS group and circulating pro-inflammatory IL-1β was elevated significantly in the sham group compared to nVNS. Levels of anti-inflammatory IL-10 were significantly higher at baseline in both groups compared to healthy controls, but not at 2 months follow-up [p?<?0.05]. Concentrations of high-mobility group box-1 (HMGB-1), IL-6, tumor-necrosis factor-α (TNF-α), leptin, adiponectin, ghrelin remained unchanged [p?>?0.05]. No severe device-/stimulation-related adverse events occurred.

Conclusion

2 months of adjunctive cervical nVNS significantly declined the number of severe attacks/month. Pro-inflammatory IL-1β plasma levels [inter-ictal] were higher in sham-treated migraine patients compared to verum nVNS. However, pro- [IL-6, HMGB-1, TNF-α, leptin] and anti-inflammatory [IL-10, adiponectin, ghrelin] mediators did not differ statistically. Profiling of neuroinflammatory circuits in migraine to predict nVNS responsiveness remains an experimental approach, which may be biased by pre-analytic variables warranting large-scale biobank-based systematic investigations [omics].  相似文献   
88.
目的探讨GATA6基因启动区-493(rs144923558)G/A、-172(rs146748749)G/A 2个位点单核苷酸多态性(SNP)与急性心肌梗死(AMI)之间的关系及其相关的危险因素。方法采用病例-对照研究方法,收集328例AMI患者和344例正常对照;应用聚合酶链反应-限制性内切酶片段长度多态性技术结合DNA测序后的序列比对进行数据统计;运用Hardy-Weinberg平衡检验后,应用χ~2检验进行相关分析;利用Logistic回归对多种危险因素以及2个SNP位点与AMI发病进行关联性分析;利用Haplovview4.2软件和SHEsis网站进行连锁不平衡及单倍体分析。结果 2个SNP位点共检测出3种基因型为GG、GA和AA,其基因型分布均符合Hardy-Weinberg平衡(P0.05),同时在AMI组与对照组间差异无显著性(P0.05)。多因素Logistic回归分析:增龄、高血压病、吸烟、低密度脂蛋白胆固醇(LDLC)和甘油三酯(TG)升高是AMI发病的独立危险因素(P0.05),HDLC为保护因素(P0.05)。在显性、隐性和加性3种不同遗传模式下进行Logistic回归分析发现,2个SNP位点与AMI发病无关联性。进行连锁不平衡和单倍型分析提示,该2个SNP位点处于同一个连锁不平衡区域(D′=1.000,r~2=1.000),单倍型GG和AA均未增加AMI易感性(P0.05)。结论 GATA6基因启动区-493(rs144923558)G/A与-172(rs146748749)G/A两个SNP位点为完全连锁不平衡,其中GG为主要单倍型。该2个SNP位点及其单倍体型与AMI发病无相关性,但提供了GATA6基因启动区多态性的群体遗传学资料。  相似文献   
89.
咳嗽临床常见,尤其是胸部影像学无明显异常的慢性咳嗽,病因复杂、易误诊误治,逐渐受到重视,国内外相继颁发相关指南,目前认为咳嗽高敏感性是其重要的病理生理机制。中医将慢性咳嗽归于"久咳""久嗽"范畴,在病因病机、治法方药上积累了丰富的临床经验,史利卿教授团队针对该病开展了专项临床及基础研究15年,根据传统中医理论及其突出临床症状提出"风邪伏肺"病机,应用祛风宣肺法治疗效果显著。文章结合西医学相关咳嗽机制研究进展及既往研究结果,初步探讨祛风宣肺法治疗该病的疗效机制,丰富慢性咳嗽风邪伏肺致咳相关学术理论的科学内涵,有利于提高中医药防治慢性咳嗽学术水平。  相似文献   
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号