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   1232篇
  免费   73篇
  国内免费   4篇
耳鼻咽喉   16篇
儿科学   28篇
妇产科学   17篇
基础医学   169篇
口腔科学   36篇
临床医学   89篇
内科学   338篇
皮肤病学   44篇
神经病学   137篇
特种医学   18篇
外科学   94篇
综合类   10篇
预防医学   123篇
眼科学   10篇
药学   83篇
中国医学   6篇
肿瘤学   91篇
  2024年   1篇
  2023年   23篇
  2022年   5篇
  2021年   46篇
  2020年   34篇
  2019年   60篇
  2018年   70篇
  2017年   37篇
  2016年   50篇
  2015年   37篇
  2014年   40篇
  2013年   78篇
  2012年   129篇
  2011年   136篇
  2010年   53篇
  2009年   38篇
  2008年   102篇
  2007年   72篇
  2006年   61篇
  2005年   73篇
  2004年   61篇
  2003年   55篇
  2002年   27篇
  2001年   4篇
  2000年   3篇
  1999年   3篇
  1998年   1篇
  1996年   2篇
  1995年   3篇
  1992年   1篇
  1990年   1篇
  1983年   1篇
  1977年   1篇
  1969年   1篇
排序方式: 共有1309条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
OBJECTIVE: To evaluate the association between FSH efficacy and FSHR alleles. DESIGN: Retrospective study. SETTING: University-based fertility unit and a private center for biomedical research. PATIENT(S): One hundred two women with ovarian function who were undergoing controlled ovarian stimulation (COS). Women were categorized as poor responders (< or =3 ovarian follicles at the end of the cycle) or normal responders (>3 follicles). INTERVENTION(S): Daily administration of exogenous FSH. MAIN OUTCOME MEASURE(S): Number of good or poor responders. RESULT(S): The allele frequency and genotype distribution of the Ser680Asn marker differed significantly between groups. Cycle cancellations were increased (21%) among women who were homozygous for Ser680 compared with Ser/Asn and Asn/Asn patients, and 36% of poor-responders were homozygous for Ser680. CONCLUSION(S): The results support a role for FSHR gene in COS outcome. However, the weight of this factor is probably low. The Ser680 allele may act in concert with other environmental and genetic factors that contribute to FSH efficacy.  相似文献   
75.
Objective To examine the characteristics, prognostic factors, and outcome of patients with severe hospital-acquired pneumonia admitted to the ICU.Design and setting Prospective observational clinical study in two medical-surgical ICUs with 16 and 20 bedsPatients and participants During a 7-year period all hospitalized patients requiring admission to either ICU for hospital-acquired pneumonia were followed up.Measurements and results We diagnosed 96 episodes of severe hospital-acquired pneumonia, and in 67 cases a causal diagnosis was made. Most episodes were late-onset pneumonia. Gram-negative micro-organisms were isolated in 51% of episodes diagnosed, and Pseudomonas aeruginosa was the most frequent pathogen isolated (24%). Clearly significant variations happened between hospitals, particularly affecting the incidence of Aspergillus spp. and Legionella pneumophila. Forty-nine patients developed septic shock (51%). Fifty-one patients died (53%). Aspergillosis and pneumonia due to P. aeruginosa were associated with the highest mortality. Septic shock (OR: 14.27) and chronic obstructive pulmonary disease (OR: 6.11) were independently associated with a poor prognosis.Conclusions Patients with severe hospital-acquired pneumonia admitted to the ICU present high mortality. The presence of septic shock and chronic obstructive pulmonary disease in conjunction with specific microorganisms are associated with a poor prognosis. Local epidemiological data combined with a patient-based approach may allow a more accurate therapy decision making.  相似文献   
76.
Capsiate and its dihydroderivatives are the major capsaicinoids of sweet pepper. These new capsaicinoids do not activate the vanilloid receptor type 1 (VR1) but they share with capsaicin (CPS)some biological activities mediated in a VR1-independent fashion. In this study we show that CPS and nordihydrocapsiate (CPT) inhibit early and late events in T cell activation, including CD69, CD25 and ICAM-1 cell surface expression, progression to the S phase of the cell cycle and proliferation in response to TCR and CD28 co-engagement. Moreover, both CPS and CPT inhibit NF-kappaB activation in response to different agents including TNF-alpha. CPS itself does not affect the DNA-binding ability of NF-kappaB but it prevents IkappaB kinase activation and IkappaBalpha degradation in a dose-dependent manner, without inhibiting the activation of the mitogen-activated protein kinases, p38, extracellular regulated kinase and c-Jun N-terminal protein kinase. Moreover, intraperitoneal pretreatment with CPT prevented mice from lethal septic shock induced by lipopolysaccharide. In a second model of inflammation CPT pretreatment greatly reduced the extensive damage in the glandular epithelium observed in the bowel of DSS-treated mice. Taken together, these results suggest that CPT and related synthetic analogues target specific pathways involved in inflammation, and hold considerable potential for dietary health benefits as well as for pharmaceutical development.  相似文献   
77.
78.
Cancer is considered a genetic disease, being classified as an accumulative somatic disorder aside of the Mendelian diseases, the chromosomopaties and the multifactorial diseases. It has been demonstrated in several human cancers that specific mutations in some genes are related to hystopathologic features and tumor progression. Thereby, mutations represent potentially valuable markers in disease-stage detection and evaluation. Mutations associated with neoplasia development and evolution are very valuable, and the related genes are classified as: oncogenes, tumor suppressing genes, DNA repairing genes and cell cycle regulator genes. The factability to determine and characterize these genes and relate them with one or several steps of tumorogenesis, makes them molecular markers that let us predict risk, make an early diagnosis, confirm a diagnosis, establish prognosis, guide the therapy and determine resistance to treatments. Molecular methods used today for analysis of this markers offer great advantages: they are vary sensitive, use a small sample, are fast, can be easily automated, are easily interpreted, allows quantitations and, very importantly, they become cheaper when a large quantity of samples are handled. In this review we mention some types of cancers and molecular methods that can be used to take advantage of their biomarkers.  相似文献   
79.
We developed and tested a single multiplex polymerase chain reaction (PCR) that detects enterotoxigenic, enteropathogenic, enteroinvasive, and Shiga toxin-producing Escherichia coli. This PCR is specific, sensitive, and rapid in detecting target isolates in stool and food. Because of its simplicity, economy, and efficiency, this protocol warrants further evaluation in large, prospective studies of polymicrobial substances.  相似文献   
80.
Gingival retraction cords are useful clinical aids but little information is available regarding desirable physical features that would preserve their integrity under tensile forces. The study aimed to establish under experimental conditions the extent to which tensile strength is affected by variation in cord diameter; impregnation with ferric sulphate (FS) or aluminium sulphate (AS); and cord hydration (wet/dry). Commercial cords and standard cotton cords were assayed in an Instron 1137 machine. Data were analysed using t-test, and one- and four-way ANOVA. Results indicated that tensile strength for 200 commercial cords was 1.4950 +/- 1.032 kg; and for 560 cotton cords was 1.2964 +/- 1.4560 kg. Cord hydration had no significant effect on tensile strength, whereas impregnation with AS or FS, a smaller diameter, and/or being a cotton cord decreased tensile strength (P < 0.001). Bivariate analyses showed that hydrated commercial cords had higher tensile strength than dry specimens; hydrated or dry cotton cords were not different. The FS-impregnated cotton cords had lower tensile strength than AS-impregnated or control cords, and the effect was greater at higher FS concentrations. This study is one of the first evaluations of the physical properties of cords, highlighting characteristics that may minimize the risk of tearing.  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