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   2279篇
  免费   156篇
  国内免费   3篇
耳鼻咽喉   4篇
儿科学   71篇
妇产科学   45篇
基础医学   349篇
口腔科学   43篇
临床医学   343篇
内科学   509篇
皮肤病学   39篇
神经病学   266篇
特种医学   36篇
外科学   165篇
综合类   14篇
一般理论   1篇
预防医学   221篇
眼科学   41篇
药学   129篇
中国医学   6篇
肿瘤学   156篇
  2023年   12篇
  2022年   29篇
  2021年   44篇
  2020年   33篇
  2019年   43篇
  2018年   54篇
  2017年   44篇
  2016年   49篇
  2015年   77篇
  2014年   104篇
  2013年   114篇
  2012年   168篇
  2011年   168篇
  2010年   78篇
  2009年   83篇
  2008年   155篇
  2007年   153篇
  2006年   144篇
  2005年   137篇
  2004年   173篇
  2003年   146篇
  2002年   151篇
  2001年   15篇
  2000年   13篇
  1999年   12篇
  1998年   31篇
  1997年   32篇
  1996年   14篇
  1995年   20篇
  1994年   15篇
  1993年   17篇
  1992年   8篇
  1991年   2篇
  1990年   8篇
  1989年   7篇
  1988年   4篇
  1987年   8篇
  1986年   6篇
  1985年   8篇
  1984年   9篇
  1983年   5篇
  1982年   6篇
  1981年   7篇
  1980年   6篇
  1979年   3篇
  1978年   6篇
  1974年   5篇
  1972年   3篇
  1965年   1篇
  1913年   2篇
排序方式: 共有2438条查询结果,搜索用时 78 毫秒
81.
BACKGROUND: Delineating asthma subphenotypes is of interest to understand the cause of the disease. Few studies have addressed the interrelationships of quantitative asthma-related traits. OBJECTIVE: We sought to study the interrelationships of allergy markers and FEV(1) in relation to asthma and sex in children and adults. METHODS: Total IgE levels, skin prick test (SPT) positivity, eosinophil counts, and FEV(1) were assessed in 299 asthmatic cases (children and adults) recruited in chest clinics and 309 nonasthmatic population-based control subjects in the French Epidemiological Study on the Genetics and Environment of Asthma, Bronchial Hyperresponsiveness, and Atopy. RESULTS: Allergy parameters were significantly higher in asthmatic cases than in control subjects for children and adults and for both sexes. Sex and age modified the pattern of concordance of high IgE levels, SPT positivity, and eosinophilia among asthmatic cases, with the greatest overlap in male children (64%) and the lowest in male adults (18%). Patterns of change over the lifespan of IgE levels, eosinophil counts, and FEV(1)/height(2) varied, with the acceleration of FEV(1) decrease being particularly evident in asthmatic adults. In adult cases and control subjects, SPT positivity (particularly to indoor allergens) was significantly related to IgE levels but not to eosinophil counts. The association of eosinophil counts with IgE levels was evident only in children. Environmental factors (smoking, pets, and country living) did not alter the patterns observed. CONCLUSIONS: Each allergy-related phenotype showed a distinct relation with asthma, with the role for eosinophils being different than that for IgE levels and SPT responses. CLINICAL IMPLICATIONS: Taking age and sex into account is essential for understanding the interrelationships of the various allergy-related phenotypes to asthma status.  相似文献   
82.
Although type 1 diabetes historically has been more common in patients eight to 19 years of age, type 2 diabetes is emerging as an important disease in this group. Type 2 diabetes accounts for 8 to 45 percent of new childhood diabetes. This article is an update from the National Diabetes Education Program on the management of type 2 diabetes in youth. High-risk youths older than 10 years have a body mass index greater than the 85th percentile for age and sex plus two additional risk factors (i.e., family history, high-risk ethnicity, acanthosis nigricans, polycystic ovary syndrome, hypertension, or dyslipidemia). Reducing overweight and impaired glucose tolerance with increased physical activity and healthier eating habits may help prevent or delay the development of type 2 diabetes in high-risk youths. The American Academy of Pediatrics does not recommend population-based screening of high-risk youths; however, physicians should closely monitor these patients because early diagnosis may be beneficial. The American Diabetes Association recommends screening high-risk youths every two years with a fasting plasma glucose test. Patients diagnosed with diabetes should receive self-management education, behavior interventions to promote healthy eating and physical activity, appropriate therapy for hyperglycemia (usually metformin and insulin), and treatment of comorbidities.  相似文献   
83.
The role of retinal microglial cells (MCs) in age-related macular degeneration (AMD) is unclear. Here we demonstrated that all retinal MCs express CX3C chemokine receptor 1 (CX3CR1) and that homozygosity for the CX3CR1 M280 allele, which is associated with impaired cell migration, increases the risk of AMD. In humans with AMD, MCs accumulated in the subretinal space at sites of retinal degeneration and choroidal neovascularization (CNV). In CX3CR1-deficient mice, MCs accumulated subretinally with age and albino background and after laser impact preceding retinal degeneration. Raising the albino mice in the dark prevented both events. The appearance of lipid-bloated subretinal MCs was drusen-like on funduscopy of senescent mice, and CX3CR1-dependent MC accumulation was associated with an exacerbation of experimental CNV. These results show that CX3CR1-dependent accumulation of subretinal MCs evokes cardinal features of AMD. These findings reveal what we believe to be a novel pathogenic process with important implications for the development of new therapies for AMD.  相似文献   
84.
PurposeThe article identifies the aspects of health and outcomes that are considered important from the perspective of ambulatory children with cerebral palsy (CP) and their parents regarding lower limb orthopaedic surgery and explores how they experience surgical interventions.MethodsFour databases (Embase, MEDLINE (Ovid), CINAHL and PsycINFO) were searched from inception to 11 April 2020. Studies were included if they: 1) they involved children or young adults diagnosed with ambulant CP or their family, 2) participants had experience with lower limb orthopaedic surgery and 3) studies employed qualitative research methods. The Critical Appraisal Skills Programme was used to appraise identified studies. The ‘Best-fit framework’ synthesis approach was used by applying the International Classification of Functioning-Children and Youth (ICF–CY) linking rules and thematic synthesis. The review process was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.ResultsSix studies were included. Four themes were generated which were linked to the ICF–CY framework: Body function and structure, Activity and participation, Environmental factors, Personal factors, as well as non-ICF–CY themes including Emotional well-being and Goal setting. Important surgical outcomes identified were pain, fatigue, movement-related function, mobility, walking ability, community life, emotional well-being, and adequate provision of public and health services.ConclusionThese findings are important for understanding patient-centred outcomes in lower limb ortho-paedics surgery and providing focus for future interventional studies aimed at improving outcomes of importance to children with CP. These findings highlight the importance of long-term support to help people negotiate the challenge of surgical regimes and to achieve good outcomes after orthopaedic surgery. The outcomes identified will contribute to the development of a core outcome set in this field.Level of evidenceIII  相似文献   
85.
European Spine Journal - Depression, anxiety, catastrophising, and fear-avoidance beliefs are key "yellow flags" (YFs) that predict a poor outcome in back patients. Most surgeons...  相似文献   
86.

Background

Animal models are useful to evaluate the efficacy of antimicrobials in experimental sepsis.

Aim

To elucidate the steps of producing an experimental model for the treatment of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae sepsis

Methods

Several ESBL inoculums ranging from 1.5x109 colony-forming units per milliliter (CFU/mL) to 2.0x1010CFU/mL were administered by peritoneal injection in adults Wistar rats. Outcomes and microbiological data of quantitative peritoneal and blood cultures were observed in untreated animals. Animals which received 2.0x1010CFU/mL inoculums were treated with single meropenem dose (30mg/kg) after one hour and those which received 1.0x1010CFU/mL inoculums were treated immediately with three doses of meropenem 50 mg/kg. Outcomes were observed for 24 hours after inoculation.

Results

Solutions with 1.5 x109 and 6.0x109 CFU/mL were not lethal within 24 hours. Inoculums of 1.0x1010CFU/mL were lethal in 80% and solutions with 2.0x1010 CFU/mL were lethal in 100% of animals. ESBL lethal sepsis (1.0x1010CFU/mL) was treated immediately with 50 mg/kg of meropenem every eight hours for 24 hours and presented 40% mortality compared with 80% mortality of the control group (p=0.033). Quantitative cultures of peritoneal fluid presented 104CFU/mL or less for treated animals compared to more than 105 for untreated animals (p=0.001).

Conclusion

Inoculums of 1.0x1010CFU/mL achieved the best results to study a model of lethal sepsis and this model of treatment of carbapenem-susceptible Enterobacteriaceae can serve as control to further evaluation of treatment of carbapenemase-producing Enterobacteriaceae models.  相似文献   
87.
Proinsulin is a key autoantigen in type 1 diabetes. Evidence in the mouse has underscored the importance of the insulin B chain region in autoimmunity to pancreatic beta cells. In man, a majority of proteasome cleavage sites are predicted by proteasome cleavage algorithms within this region. To study CD8+ T cell responses to the insulin B chain and adjacent C peptide, we selected 8- to 11-mer peptides according to proteasome cleavage patterns obtained by digestion of two peptides covering proinsulin residues 28 to 64. We studied their binding to purified HLA class I molecules and their recognition by T cells from diabetic patients. Peripheral blood mononuclear cells from 17 of 19 recent-onset and 12 of 13 long-standing type 1 diabetic patients produced IFN-gamma in response to proinsulin peptides as shown by using an ELISPOT assay. In most patients, the response was against several class I-restricted peptides. Nine peptides were recognized within the proinsulin region covering residues 34 to 61. Four yielded a high frequency of recognition in HLA-A1 and -B8 patients. Three peptides located in the proinsulin region 41-51 were shown to bind several HLA molecules and to be recognized in a high percentage of diabetic patients.  相似文献   
88.
89.

Background  

Leishmaniases are among the most proteiform parasitic infections in humans ranging from unapparent to cutaneous, mucocutaneous or visceral diseases. The various clinical issues depend on complex and still poorly understood mechanisms where both host and parasite factors are interacting. Among the candidate factors of parasite virulence are the A2 genes, a family of multiple genes that are developmentally expressed in species of the Leishmania donovani group responsible for visceral diseases (VL). By contrast, in L. major determining cutaneous infections (CL) we showed that A2 genes are present in a truncated form only. Furthermore, the A2 genomic sequences of L. major were considered subsequently to represent non-expressed pseudogenes [1]. Consequently, it was suggested that the structural and functional properties of A2 genes could play a role in the differential tropism of CL and VL leishmanias. On this basis, it was of importance to determine whether the observed structural/functional particularities of the L. major A2 genes were shared by other CL Leishmania, therefore representing a proper characteristic of CL A2 genes as opposed to those of VL isolates.  相似文献   
90.
BACKGROUND AND AIMS: Hereditary tyrosinemia type I (HTI) is a recessively inherited disease caused by a deficiency of fumarylacetoacetate hydrolase (FAH), the last enzyme of the tyrosine catabolic pathway. The mosaic pattern of FAH expression observed in the livers of >85% of studied patients was shown to result from the correction of the mutation in one of the FAH alleles. Bilateral cell trafficking can occur between mother and fetus and such an event could be responsible for the chimerism observed in some diseases. It also has been reported that the liver repopulation observed in a HTI murine model by serial transplantation of bone marrow-derived cells was caused by a fusion of these cells to host hepatocytes. These observations led us to test the possibility that the transfer of nucleated heterozygous maternal cells in the fetal circulation could be responsible for the mosaic liver expression of FAH in HTI patients. METHODS: We used polymorphic markers of short cytosine-adenine DNA repeats to compare DNA from corrected liver sections of 4 HTI patients with DNA from their parents' blood. RESULTS: Genotyping showed that only one maternal allele is present in DNA isolated from FAH-expressing liver nodules of each proband for at least 1 marker. CONCLUSIONS: The corrected liver nodules in HTI patients are not of maternal origin and do not support cell trafficking and cell fusion as mechanisms of correction of the gene defect in hepatocytes of tyrosinemia patients.  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