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   1325篇
  免费   72篇
  国内免费   5篇
耳鼻咽喉   16篇
儿科学   44篇
妇产科学   34篇
基础医学   138篇
口腔科学   45篇
临床医学   73篇
内科学   282篇
皮肤病学   11篇
神经病学   96篇
特种医学   45篇
外国民族医学   1篇
外科学   257篇
综合类   43篇
预防医学   48篇
眼科学   21篇
药学   124篇
中国医学   6篇
肿瘤学   118篇
  2023年   15篇
  2022年   10篇
  2021年   41篇
  2020年   21篇
  2019年   32篇
  2018年   39篇
  2017年   20篇
  2016年   32篇
  2015年   32篇
  2014年   47篇
  2013年   58篇
  2012年   83篇
  2011年   104篇
  2010年   42篇
  2009年   41篇
  2008年   71篇
  2007年   80篇
  2006年   65篇
  2005年   64篇
  2004年   43篇
  2003年   35篇
  2002年   53篇
  2001年   39篇
  2000年   30篇
  1999年   25篇
  1998年   11篇
  1997年   11篇
  1996年   5篇
  1995年   7篇
  1992年   12篇
  1991年   11篇
  1990年   11篇
  1989年   13篇
  1988年   16篇
  1987年   24篇
  1986年   16篇
  1985年   15篇
  1984年   7篇
  1983年   6篇
  1982年   5篇
  1981年   7篇
  1980年   6篇
  1979年   14篇
  1978年   8篇
  1977年   7篇
  1976年   8篇
  1974年   8篇
  1973年   9篇
  1970年   5篇
  1968年   12篇
排序方式: 共有1402条查询结果,搜索用时 375 毫秒
51.
Environmental enrichment (EE) has an influential role in reducing behavioral reactivity to stress. We previously observed that EE reduces the anxiety‐like behavior in the field mouse Mus booduga accompanied by a reduction in the expression of molecules involved in the stress pathway. In this study, we demonstrate the effect of different housing condition on regulation of micro‐RNA‐183‐SC35‐mediated splicing of acetylcholinesterase (AChE). Adult male M. booduga were captured from an agricultural field and housed under nonenriched standard conditions (SC) for 7 days and considered as directly from the wild (DW). On day 8, individuals were randomly assigned to three groups; DW, SC, and EE. The DW group's anxiety‐like behavior was assessed in the elevated plus maze (EPM) and open field test (OFT). The SC and EE groups were transferred to their respective conditions and housed for another 30 days. The mice housed in EE showed less anxiety‐like behavior on EPM and in OFT compared with DW and SC mice. Interestingly, miR‐183 expression was increased following exposure to EPM in EE mice but not in SC mice. Subsequently, the upregulated miR‐183 expression suppresses the SC35 expression and shifting of splicing from AChE‐S (synaptic) to AChE‐R (read‐through) form, whereas standard housing condition downregulate miR‐183 and induces the splicing of AChE. The upregulated AChE‐R form possibly terminates ACh transmission, which is reflected in the level of anxiety‐like behavior. Overall, the present study suggests that EE effectively regulates the miR‐183 pathway to reduce anxiety‐like behavior. © 2012 Wiley Periodicals, Inc.  相似文献   
52.
53.
Objectives: To obtain data on the prevalence of oral mucosal lesions (OMLs) among Cambodians, and to assess the relationship between known risk habits of oral diseases with prevalence of oral potentially malignant disorders (OPMDs).

Design: This was a population-based, cross-sectional study whereby subjects were adults aged 18 years old and above. A workshop on the identification of OML was held to train and calibrate dental officers prior to data collection in the field. Sociodemographic and risk habits data were collected via face-to-face interview, whilst presence of OML and clinical details of lesions such as type and site were collected following clinical oral examination by the examiners. Data analysis was carried out using the Statistical Package for Social Science (SPSS) version 12.0. The association between risk habits and risk of OPMD was explored using logistic regression analysis.

Results: A total of 1634 subjects were recruited. Prevalence of OML for this population was 54.1%. Linea alba was the most common lesion seen (28.7%). This study showed an overall OPMD prevalence of 5.6%. The most common type of OPMD was leukoplakia (64.8%), followed by lichen planus (30.8%). Subjects who only smoked were found to have an increased risk for OPMD of almost four-fold (RR 3.74, 95%CI 1.89–7.41). The highest risk was found for betel quid chewers, where the increased risk observed was more than six times (RR 6.75, 95%CI 3.32–13.72). Alcohol consumption on its own did not seem to confer an increased risk for OPMD, however when practiced concurrently with smoking, a significant risk of more than five times was noted (RR 5.69 95%CI 3.14–10.29).

Conclusion: The prevalence of OML was 54.1%, with linea alba being the most commonly occurring lesion. Smoking, alcohol consumption and betel quid chewing were found to be associated with the prevalence of OPMD, which was 5.6%.  相似文献   

54.
To assess the efficacy of an antibiofilm/antimicrobial agent combination, we incubated catheter segments colonized with one of six studied bacterial organisms in N-acetylcysteine, tigecycline, N-acetylcysteine-tigecycline, or saline. Segments were washed, sonicated, and cultured. N-acetylcysteine-tigecycline significantly decreased all viable biofilm-associated bacteria and was synergistic for methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis.  相似文献   
55.
This study aims to develop a spatial model of bone for quantitative assessments of bone mineral density and microarchitecture. A spatially structured network model for bone microarchitecture was systematically investigated. Bone mineral-forming foci were distributed radially according to the cumulative normal distribution, and Voronoi tessellation was used to obtain edges representing bone mineral lattice. Methods to simulate X-ray images were developed. The network model recapitulated key features of real bone and contained spongy interior regions resembling trabecular bone that transitioned seamlessly to densely mineralized, compact cortical bone-like microarchitecture. Model-simulated imaging profiles were similar to patients’ X-ray images. The morphometric metrics were concordant with microcomputed tomography results for real bone. Simulations comparing normal and diseased bone of 20–30 to 70–80 year-olds demonstrated the method’s effectiveness for modeling osteoporosis. The novel spatial model may be useful for pharmacodynamic simulations of bone drugs and for modeling imaging data in clinical trials.  相似文献   
56.
Accurate recognition of movement disorder phenomenology may differentiate children with anti‐N‐methyl D‐aspartate receptor (NMDAR) encephalitis, autoimmune basal ganglia encephalitis (BGE), and Sydenham's chorea (SC). Three neurologists blinded to the diagnoses recorded dominant and associated movement disorders seen on videos of 31 patients with anti‐NMDAR encephalitis (n = 10), BGE (n = 12), and SC (n = 9). Stereotypy was only seen in anti‐NMDAR encephalitis (8/10) and not in BGE and SC (P < 0.001). Perseveration was only seen in anti‐NMDAR encephalitis (5/10) and not in BGE and SC (P < 0.001). Akinesia was more commonly seen in BGE (5/12) than in anti‐NMDAR encephalitis (1/10, P = 0.097). Tremor was more commonly seen in BGE (5/12) than in anti‐NMDAR encephalitis (1/10, P = 0.097). Chorea was seen in all groups: anti‐NMDAR encephalitis (4/10), BGE (3/12), and SC (9/9). Likewise, dystonia was seen in all groups: anti‐NMDAR encephalitis (6/10), BGE (7/12), and SC (2/9). Stereotypies or perseveration are suggestive of anti‐NMDAR encephalitis, whereas their absence and the presence of akinesia and tremor is more suggestive of BGE. Chorea and dystonia are least discriminating. © 2014 International Parkinson and Movement Disorder Society  相似文献   
57.
58.
NP260 was designed as a first-in-class selective antagonist of α4-subtype GABAA receptors that had promising efficacy in animal models of pain, epilepsy, psychosis, and anxiety. However, development of NP260 was complicated following a 28-day safety study in dogs in which pronounced elevations of serum aminotransferase levels were observed, although there was no accompanying histopathological indication of hepatocellular injury. To further investigate the liver effects of NP260, we assayed stored serum samples from the 28-day dog study for liver specific miRNA (miR-122) as well as enzymatic biomarkers glutamate dehydrogenase and sorbitol dehydrogenase, which indicate liver necrosis. Cytotoxicity assessments were conducted in hepatocytes derived from dog, rat, and human liver samples to address the species specificity of the liver response to NP260. All biomarkers, except ALT, returned toward baseline by Day 29 despite continued drug treatment, suggesting adaptation to the initial injury. In vitro analysis of the toxicity potential of NP260 to primary hepatocytes indicated a relative sensitivity of dog > human > rat, which may explain, in part, why the liver effects were not evident in the rodent safety studies. Taken together, the data indicate that a diagnostic biomarker approach, coupled with sensitive in vitro screening strategies, may facilitate interpretation of toxicity potential when an adaptive event masks the underlying toxicity.  相似文献   
59.
A series of functionalized 3,4-dihydroquinolinium salts were prepared from the reaction of aryldiazonium salt with alkene in a nitrile solution. Further oxidation yielding either 3-hydroxyquinoline or quinoline products was investigated. A one-pot process from aryldiazonium salts, alkenes and nitriles leading to 3-hydroxyquinolines was also developed. Furthermore, an intramolecular trapping of an N-arylnitrilium ion with a vinyl group at the ortho position leading to 2-substituted quinolines was revealed.

3-Hydroxyquinoline derivatives can be prepared by a cascade cyclization of aryldiazonium salts with nitriles and alkenes followed by oxygenation.  相似文献   
60.
Oncogenic activation of tyrosine kinase signaling pathway is recurrent in human leukemia. To gain insight into the oncogenic process leading to acute megakaryoblastic leukemia (AMKL), we performed sequence analyses of a subset of oncogenes known to be activated in human myeloid and myeloproliferative disorders. In a series of human AMKL samples from both Down syndrome and non-Down syndrome patients, mutations were identified within KIT, FLT3, JAK2, JAK3, and MPL genes, with a higher frequency in DS than in non-DS patients. The novel mutations were analyzed using BaF3 cells, showing that JAK3 mutations were activating mutations. Finally, we report a novel constitutively active MPL mutant, MPLT487A, observed in a non-Down syndrome childhood AMKL that induces a myeloproliferative disease in mouse bone marrow transplantation assay.  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