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   346872篇
  免费   24769篇
  国内免费   12930篇
耳鼻咽喉   3654篇
儿科学   9813篇
妇产科学   4469篇
基础医学   51305篇
口腔科学   7590篇
临床医学   35900篇
内科学   58186篇
皮肤病学   5691篇
神经病学   19685篇
特种医学   16198篇
外国民族医学   48篇
外科学   43008篇
综合类   38125篇
现状与发展   51篇
一般理论   2篇
预防医学   18789篇
眼科学   7297篇
药学   34519篇
  133篇
中国医学   8712篇
肿瘤学   21396篇
  2024年   550篇
  2023年   3281篇
  2022年   10575篇
  2021年   13904篇
  2020年   8928篇
  2019年   14573篇
  2018年   9523篇
  2017年   9147篇
  2016年   11444篇
  2015年   14702篇
  2014年   25041篇
  2013年   24604篇
  2012年   25825篇
  2011年   23687篇
  2010年   21011篇
  2009年   20314篇
  2008年   19227篇
  2007年   19175篇
  2006年   16735篇
  2005年   12358篇
  2004年   8160篇
  2003年   7001篇
  2002年   5476篇
  2001年   4627篇
  2000年   4028篇
  1999年   3093篇
  1998年   3451篇
  1997年   3225篇
  1996年   2796篇
  1995年   2877篇
  1994年   2711篇
  1993年   2268篇
  1992年   2140篇
  1991年   1916篇
  1990年   1867篇
  1989年   1767篇
  1988年   1585篇
  1987年   1399篇
  1986年   1173篇
  1985年   2386篇
  1984年   2522篇
  1983年   1799篇
  1982年   2004篇
  1981年   1833篇
  1980年   1586篇
  1979年   1385篇
  1978年   1046篇
  1977年   973篇
  1976年   878篇
  1974年   540篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
192.
In order to solve the problem of long-term (>9 months) efficacy in the treatment of Alzheimer''s disease (AD) by conventional therapy (CT), a staged and multiply-targeted sequential therapy based on the evolvement of patterns (STEP) was developed. Its main innovations include: (1) the time order of evolution of patterns defined by Chinese medicine (CM) in AD was found, that is, "the orderly pattern evolution starting from Shen (Kidney) deficiency, progressing to phlegm, stasis and fire, and worsening to severe toxin as well as functional collapse"; (2) the cascade hypothesis of Shen deficiency in AD and its sequential therapy based on Shen-reinforcing was proposed, that is, "reinforcing Shen in the early stage and throughout the whole process, resolving phlegm, activating blood and purging fire in the middle stage, detoxifying and replenishing vitality to stop the collapse in the advanced stage", and through meta-analysis, clinical drug use was optimized, thus the leap from "inferential selection" to "evidence-based selection" was realized; (3) the STEP regimen combined with CT maintained cognitive and behavioral stability in AD patients for at least 12 months, with cognitive enhancement and behavioral synergy after 9 months, and cognitive benefit was superior to CT at 9, 12, 15, 18, 21, and 24 months, respectively. The 2-year cognitive improvement rate was increased by 25.64% (P=0.020) and the cognitive deterioration rate was decreased by 48.71% (P=0.000). Among them, the cognitive and functional benefits of Shen-reinforcing therapy for very early AD (350 cases) for 1 year were better than the placebo (P<0.001), and the dementia conversion rate was reduced by 8.85% (P=0.002). The behavioral symptomatic relief of patients with vascular dementia received fire-purging therapy (540 cases) was superior to those received CT (P=0.016). These data suggested that the STEP regimen has synergistic effects on CTs at least in terms of cognitive benefit, and the earlier the use, the greater the benefit will have. Therefore, the STEP regimen should be considered as one of the clinical options, particularly for the dearth of effective pharmaceutical or immunological interventions that are currently available for AD.  相似文献   
193.
目的探讨负载 IL-4 和 BMP-2 的氧化石墨烯(graphene oxide,GO)-羧甲基壳聚糖(carboxymethyl chitosan,CMC)凝胶诱导巨噬细胞 M2 型分化及对 BMSCs 成骨分化的影响。方法取 CMC、GO 制备混合溶液后,分别添加 PBS、IL-4、BMP-2 或 IL-4+BMP-2,在交联剂作用下制备单纯或负载不同因子的 GO-CMC 凝胶支架;取单纯 GO-CMC 凝胶表征观测,包括大体、扫描电镜及傅里叶变换红外吸收光谱仪(Fourier transform infrared spectroscopy,FTIR)检测,以单纯 CMC 凝胶作为对照;取负载不同因子的 GO-CMC 凝胶行体外缓释实验。取 4~5 周龄 SPF 级 SD 雌性大鼠分离培养巨噬细胞,分别与单纯以及负载不同因子的 GO-CMC 凝胶培养,24 h 后行 CD206 免疫荧光检测巨噬细胞分化情况;取第 3 代大鼠 BMSCs 分别与单纯以及负载不同因子的 GO-CMC 凝胶成骨诱导培养,10 d 后行 ALP 染色观测早期成骨,21 d 行茜素红染色观测晚期成骨。结果大体观察 GO-CMC 凝胶呈棕色、半透明状;扫描电镜观察示,GO-CMC 凝胶孔径及孔壁厚度与单纯 CMC 凝胶相似,但内壁粗糙度增加;FTIR 检测显示 CMC 发生聚合形成凝胶。体外缓释实验示 3 种负载不同因子的 GO-CMC 凝胶缓释性能相似,均呈线性缓慢释放因子。CD206 免疫荧光检测示 GO-CMC 凝胶可诱导巨噬细胞 M2 型分化,ALP 及茜素红染色示 GO-CMC 凝胶可诱导 BMSCs 成骨分化;其中负载 IL-4+BMP-2 的 GO-CMC 凝胶作用最显著(P<0.05)。 结论负载 IL-4 和 BMP-2 的 GO-CMC 凝胶可诱导巨噬细胞 M2 型分化,增强 BMSCs 成骨分化能力,为后期骨缺损修复及骨免疫调节研究提供了新的策略。  相似文献   
194.
Metastatic melanoma is the most deadly skin neoplasm in the United States. Outcomes for this lethal disease have improved dramatically due to the use of both targeted and immunostimulatory drugs. Immunogenic cell death (ICD) has emerged as another approach for initiating antitumor immunity. ICD is triggered by tumor cells that display damage-associated molecular patterns (DAMPs). These DAMP molecules recruit and activate dendritic cells (DCs) that present tumor-specific antigens to T cells which eliminate neoplastic cells. Interestingly, the expression of DAMP molecules occurs in an endoplasmic reticulum (ER) stress-dependent manner. We have previously shown that ER stress was required for the cytotoxic activity of the endocannabinoid metabolite, 15-deoxy, Δ12,14 prostamide J2 (15dPMJ2). As such, the current study investigates whether 15dPMJ2 induces DAMP signaling in melanoma. In B16F10 cells, 15dPMJ2 caused a significant increase in the cell surface expression of calreticulin (CRT), the release of ATP and the secretion of high-mobility group box 1 (HMGB1), three molecules that serve as surrogate markers of ICD. 15dPMJ2 also stimulated the cell surface expression of the DAMP molecules, heat shock protein 70 (Hsp70) and Hsp90. In addition, the display of CRT and ATP was increased by 15dPMJ2 to a greater extent in tumorigenic compared to non-tumorigenic melanocytes. Consistent with this finding, the activation of bone marrow-derived DCs was upregulated in co-cultures with 15dPMJ2-treated tumor compared to non-tumor melanocytes. Moreover, 15dPMJ2-mediated DAMP exposure and DC activation required the electrophilic cyclopentenone double bond within the structure of 15dPMJ2 and the ER stress pathway. These results demonstrate that 15dPMJ2 is a tumor-selective inducer of DAMP signaling in melanoma.  相似文献   
195.
About 10% of patients with Lyme disease continue to experience musculoskeletal pain and cognitive dysfunction after recommended antibiotic treatment. This condition is called post-Lyme disease syndrome (PLDS) or post-treatment Lyme disease syndrome. These two terms are used interchangeably. The pathogenesis of PLDS has been controversial. The hypothesis that patients with PLDS may harbor hidden reservoirs of Borrelia burgdorferi after their initial antibiotic treatment is difficult to accept. The prospective, double-blind studies contradict this point of view. Also, recently published research applying xenodiagnosis to PLDS supports the opinion that PLDS most likely has an autoimmune background. Lengthy courses of antibiotics are not justified in patients with PLDS because of the lack of benefit, and they are fraught with hazards. Most patients with PLDS recover from persistent symptoms with time. However, it can take months before they feel completely well.  相似文献   
196.
《Journal of endodontics》2019,45(7):890-897
IntroductionThe aim was to assess the association of inducible costimulator (ICOS) and ICOS ligand with bone destruction in apical periodontitis (AP).MethodsSpecimens from patients presenting with AP were obtained during apicoectomy and subjected to histopathologic analysis and molecular assessment of ICOS/ICOS ligand. In addition, the experimental AP was induced by exposing the pulp of first mandibular molars of rats. Histologic and radiographic examinations were performed to validate the periapical lesions. The immunolocalization and messenger RNA expression of ICOS/ICOS ligand were evaluated by immunofluorescence staining and quantitative real-time polymerase chain reaction. The osteoclastic activities in periapical lesions, including the lesion size and the expression of tartrate-resistant acid phosphatase and the receptor activator of nuclear factor kappa B ligand, were recorded and followed by correlation analysis with ICOS/ICOS ligand expression.ResultsIn excisional specimens from AP patients, a significantly increased expression of ICOS/ICOS ligand was found compared with the healthy control. In the experimental AP samples, the expression of ICOS/ICOS ligand, tartrate-resistant acid phosphatase, and receptor activator of nuclear factor kappa B ligand was significantly elevated in inflamed periapical tissues (AP group) when compared with the healthy control. The number of ICOS+/ICOS ligand+ cells was highly correlated with the periapical lesion size (r = 0.892, P < .01 and r = 0.930, P < .01, respectively).ConclusionsThe increased expression of ICOS/ICOS ligand in periapical lesions was associated with the inflammatory infiltration and alveolar bone destruction of AP.  相似文献   
197.
198.
《Vaccine》2020,38(10):2315-2325
In the preparation of glycoconjugate vaccines in clinical practice, two highly immunogenic carrier proteins, CRM197 and tetanus toxoid (TT), are predominantly conjugated with the capsular polysaccharides (CPSs) of bacterial pathogens. In addition, TT has long been used as an effective vaccine to prevent tetanus. While these carrier proteins play an important role in immunogenicity and vaccine design alike, their defined human major histocompatibility complex class II (MHCII) T cell epitopes are inadequately characterized. In this current work, we use mass spectrometry to identify the peptides from these carrier proteins that are naturally processed and presented by human B cells via MHCII pathway. The MHCII-presented peptides are screened for their T cell stimulation using primary CD4+ T cells from four healthy adult donors. These combined methods reveal a subset of eleven CD4+ T cell epitopes that proliferate and stimulate human T cells with diverse MHCII allelic repertoire. Six of these peptides stand out as potential immunodominant epitopes by responding in three or more donors. Additionally, we provide evidence of these natural epitopes eliciting more significant T cell responses in donors than previously published TT peptides selected from T cell epitope screening. This study serves toward understanding carrier protein immune responses and thus enables the use of these peptides in developing novel knowledge-based vaccines to combat persisting problems in glycoconjugate vaccine design.  相似文献   
199.
ABSTRACT

Purpose

New instrument-based techniques for anterior chamber (AC) cell counting can offer automation and objectivity above clinician assessment. This review aims to identify such instruments and its correlation with clinician estimates.  相似文献   
200.
BackgroundDistal radial access (DRA) has been proposed to improve procedure ergonomics and favor radial artery patency. Although promising data, nothing is known on evolving hand function after DRA.ObjectivesThis study sought to comprehensively evaluate hand function in patients undergoing DRA.MethodsReal-world patients undergoing DRA undertook a thorough multimodality assessment of hand function implementing multidomain questionnaires (Disabilities of the Arm, Shoulder and Hand and Levine-Katz), and motor (pinch grip test) and sensory (Semmes-Weinstein monofilaments test) examinations of both hands. All assessments were performed at preprocedural baseline and planned at 1-, 6-, and 12-month follow-up (FU). Adverse clinical and procedural events were documented too.ResultsData of 313 patients (220 men, age 66 ± 10 years) from 9 international centers were analyzed. The Disabilities of the Arm, Shoulder and Hand and the Levine-Katz scores slightly improved from baseline to FU (P = 0.008 and P = 0.029, respectively). Pinch strength mildly improved from baseline to FU (P < 0.001 for both the left and right hands). Similarly, touch pressure threshold appeared to faintly improve in both the left and right hands (P < 0.012 for all the sites). For both motor and sensory function tests, comparable findings were found for the DRA hand and the contralateral one, with no significant differences between them. Repeated assessment of all tests over all FU time points similarly showed lack of worsening hand function. Access-related adverse events included 19 harmless bleedings and 3 forearm radial artery and 3 distal radial artery occlusions. None affected hand function at FU.ConclusionsIn a systematic multidimensional assessment, DRA was not associated with hand function impairment. Moreover, DRA emerges as a safe alternative vascular access.  相似文献   
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