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   12101篇
  免费   670篇
  国内免费   64篇
耳鼻咽喉   154篇
儿科学   256篇
妇产科学   201篇
基础医学   1798篇
口腔科学   1189篇
临床医学   915篇
内科学   2593篇
皮肤病学   316篇
神经病学   956篇
特种医学   189篇
外科学   1194篇
综合类   40篇
一般理论   3篇
预防医学   1223篇
眼科学   190篇
药学   795篇
中国医学   122篇
肿瘤学   701篇
  2024年   11篇
  2023年   171篇
  2022年   360篇
  2021年   623篇
  2020年   371篇
  2019年   443篇
  2018年   545篇
  2017年   351篇
  2016年   377篇
  2015年   480篇
  2014年   658篇
  2013年   747篇
  2012年   1012篇
  2011年   1107篇
  2010年   564篇
  2009年   418篇
  2008年   682篇
  2007年   639篇
  2006年   636篇
  2005年   481篇
  2004年   460篇
  2003年   338篇
  2002年   286篇
  2001年   131篇
  2000年   139篇
  1999年   112篇
  1998年   64篇
  1997年   36篇
  1996年   33篇
  1995年   39篇
  1994年   24篇
  1993年   22篇
  1992年   70篇
  1991年   51篇
  1990年   38篇
  1989年   44篇
  1988年   32篇
  1987年   24篇
  1986年   25篇
  1985年   25篇
  1984年   19篇
  1983年   17篇
  1982年   8篇
  1979年   12篇
  1978年   9篇
  1977年   8篇
  1973年   9篇
  1970年   10篇
  1969年   8篇
  1966年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The malignant transformation and expansion of tumor cells involve both cell-autonomous mechanisms and microenvironment signals that regulate viability, nutrient utilization, metabolic activity and cell growth. In T-cell acute lymphoblastic leukemia (T-ALL), the co-culture of leukemic cells with stroma or the addition of particular cytokines prevents ex vivo spontaneous apoptosis. Interleukin-7 (IL-7), a cytokine produced by thymic and bone marrow stroma, increases the viability and proliferation of T-ALL cells. IL-7 induces the activation of Jak/STAT, MEK/Erk and PI3K/Akt signaling pathways in T-ALL cells. PI3K/Akt is the dominant pathway that mediates the effects of IL-7 on T-ALL. PI3K signaling is required for the induction of Bcl-2, the down-regulation of p27(kip1) and cell cycle progression. PI3K signaling is also required for the expression of the glucose transporter Glut1, uptake of glucose, activation of the metabolic machinery, increase in cell size, and maintenance of mitochondrial integrity. These observations suggest that substrates of molecular pathways activated by microenvironmental factors represent attractive molecular targets for the regulation of the viability and proliferation of T-ALL cells and provide the means for the development of novel treatment strategies.  相似文献   
102.
103.
Little is known about the impact of enrollment on therapeutic clinical trials on adverse event rates. Primary objective was to describe the impact of clinical trial registration on sterile site microbiologically documented infection for children with newly diagnosed acute myeloid leukemia (AML). We conducted a multicenter cohort study that included children aged ≤18 years with de novo AML. Primary outcome was microbiologically documented sterile site infection. Infection rates were compared between those registered and not registered on clinical trials. Five hundred seventy‐four children with AML were included of which 198 (34.5%) were registered on a therapeutic clinical trial. Overall, 400 (69.7%) had at least one sterile site microbiologically documented infection. In multiple regression, registration on clinical trials was independently associated with a higher risk of microbiologically documented sterile site infection [adjusted odds ratio (OR) 1.24, 95% confidence interval (CI) 1.01–1.53; p = 0.040] and viridans group streptococcal infection (OR 1.46, 95% CI 1.08–1.98; p = 0.015). Registration on trials was not associated with Gram‐negative or invasive fungal infections. Children with newly diagnosed AML enrolled on clinical trials have a higher risk of microbiologically documented sterile site infection. This information may impact on supportive care practices in pediatric AML.  相似文献   
104.
105.
Starting from the well-known antimicrobial properties of silver nanoparticles, the goal of this study is to evaluate the influence of two “green” recipes, namely an alcoholic extract of Dryopteris filix-mas (L.) Schott and a dispersion of silver nanoparticles phytosynthesized using the extract on grapevine pathogens. The influence of some grapevine parameters (pith/wood rapport, soluble sugars, starch, total sugars, total water content, length of young shoots, number of grapes) in field experiments was also studied. The study was conducted on four clones (Feteasca alba 97 St., Feteasca neagra 6 St., Feteasca regala 72 St., and Cabernet Sauvignon 131 St.) located in vegetation pots inside a greenhouse. For the phytosynthesis of the silver nanoparticles (AgNPs) we used a scaled-up technology, allowing us to obtain large quantities of nanoparticles-containing solution. The AgNPs analysis by X-ray diffraction and transmission electron microscopy confirmed the synthesis of spherical and quasi-spherical nanoparticles of 17 nm average diameter and 6.72 nm crystallite size. The field experiments registered different responses of the four clones to the treatment, using both the natural extracts and phytosynthesized nanoparticles solution. Both recipes exhibited a protective effect against the Uncinula necator pathogen. For the treatment using phytosynthesized nanoparticles, significant increases in the pith/wood ratio for white wine clones (Feteasca alba 97 St. and Feteasca regala 72 St.) were observed. The biochemical analyses revealed other significant increases of soluble sugars (red wine clones—Feteasca neagra and Cabernet Sauvignon/second year), starch (Feteasca alba and Cabernet Sauvignon in 2021 for both clones), total sugars (Feteasca alba and Feteasca neagra in 2021 for both clones), and of total water content (Feteasca alba and Feteasca neagra in 2021 for both clones), respectively. The applied treatments also led to an increase of young shoots length and grape numbers for all clones as compared to the control (chemical pesticide), which would suggest a potential biostimulant effect of the recipes.  相似文献   
106.
Background: The occurrence of bone fractures is increasing worldwide, mainly due to the health problems that follow the aging population. The use of additive manufacturing and electrical stimulators can be applied for bioactive achievements in bone healing. However, such technologies are difficult to be transferred to medical practice. This work aims to develop an orthosis with a combined magnetic field (CFM) electrostimulator that demonstrates concepts and design aspects that facilitate its use in a real scenario. Methods: A 3D-printed orthosis made of two meshes was manufactured using PLA for outer mechanical stabilization mesh and TPU for inner fixation mesh to avoid mobilization. A CFM stimulator of reduced dimension controlled by a mobile application was coupled onto the orthosis. The design concepts were evaluated by health professionals and their resistance to chemical agents commonly used in daily activities were tested. Their thermal, chemical and electrical properties were also characterized. Results: No degradation was observed after exposure to chemical agents. The CMF achieved proper intensity (20–40 µT). The thermal analysis indicated its appropriate use for being modelled during clinical assessment. Conclusion: An orthosis with a coupled electrostimulator that works with a combined magnetic field and is controlled by mobile application was developed, and it has advantageous characteristics when compared to traditional techniques for application in real medical environments.  相似文献   
107.
Chikungunya virus (CHIKV) vertical transmission occurs due to maternal viremia in the prepartum. Clinical presentation in neonates can be varied; however, the consequences of intrauterine exposure on the immune response are unclear. Thus, we aimed to analyze inflammatory alterations in children exposed to maternal CHIKV infection. This is a cross-sectional study that included children exposed to maternal CHIKV infection (confirmed by RT-qPCR and/or IgM). Circulant immune mediators were analyzed by a multiplex assay. RESULTS: We included 33 children, with a mean age of 3 ± 2.9 months-old, and 19 (57.6%) were male. Only one child presented neurological alterations. CHIKV-exposed infants showed elevated levels of MIP-1α, MIP-1β, and CCL-2 (p < 0.05). Pro-inflammatory cytokines such as TNFα, IL-6, and IL-7 (p < 0.0001) were also increased. In addition, lower levels of PDGF-BB and GM-CSF were observed in the same group (p < 0.0001). Principal component (PC) analysis highlighted a distinction in the inflammatory profile between groups, where PC explained 56.6% of the alterations. Our findings suggest that maternal exposure to CHIKV can affect the circulating levels of pro-inflammatory cytokines during the infants’ first year of life. The long-term clinical consequences of these findings should be investigated.  相似文献   
108.
109.
Background p53 mutants contribute to the chronic inflammatory tumour microenvironment (TME). In this study, we address the mechanism of how p53 mutants lead to chronic inflammation in tumours and how to transform it to restore cancer immune surveillance.Methods Our analysis of RNA-seq data from The Cancer Genome Atlas Breast Invasive Carcinoma (TCGA-BRCA) project revealed that mutant p53 (mtp53) cancers correlated with chronic inflammation. We used cell-based assays and a mouse model to discover a novel gain of function of mtp53 and the effect of the mtp53 reactivating compound APR-246 on the anti-tumour immune response.Results We found that tumour samples from patients with breast carcinoma carrying mtp53 showed elevated Interferon (IFN) signalling, Tumour Inflammation Signature (TIS) score and infiltration of CD8+ T cells compared to wild type p53 (wtp53) tumours. We showed that the expression of IFN and immune checkpoints were elevated in tumour cells in a mtp53-dependent manner, suggesting a novel gain of function. Restoration of wt function to mtp53 by APR-246 induced the expression of endogenous retroviruses, IFN signalling and repressed immune checkpoints. Moreover, APR-246 promoted CD4+ T cells infiltration and IFN signalling and prevented CD8+ T cells exhaustion within the TME in vivo.Conclusions Breast carcinomas with mtp53 displayed enhanced inflammation. APR-246 boosted the interferon response or represses immune checkpoints in p53 mutant tumour cells, and restores cancer immune surveillance in vivo. Subject terms: Immunosurveillance, Targeted therapies  相似文献   
110.
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