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   1631篇
  免费   101篇
  国内免费   9篇
耳鼻咽喉   17篇
儿科学   63篇
妇产科学   35篇
基础医学   199篇
口腔科学   43篇
临床医学   86篇
内科学   392篇
皮肤病学   51篇
神经病学   148篇
特种医学   43篇
外科学   197篇
综合类   5篇
预防医学   180篇
眼科学   30篇
药学   97篇
中国医学   2篇
肿瘤学   153篇
  2023年   11篇
  2022年   18篇
  2021年   49篇
  2020年   31篇
  2019年   48篇
  2018年   52篇
  2017年   57篇
  2016年   49篇
  2015年   33篇
  2014年   64篇
  2013年   84篇
  2012年   120篇
  2011年   115篇
  2010年   51篇
  2009年   62篇
  2008年   88篇
  2007年   98篇
  2006年   90篇
  2005年   99篇
  2004年   74篇
  2003年   70篇
  2002年   60篇
  2001年   35篇
  2000年   46篇
  1999年   43篇
  1998年   18篇
  1997年   4篇
  1996年   11篇
  1995年   6篇
  1994年   8篇
  1993年   6篇
  1992年   13篇
  1991年   25篇
  1990年   14篇
  1989年   15篇
  1988年   13篇
  1987年   13篇
  1986年   8篇
  1985年   9篇
  1982年   2篇
  1979年   4篇
  1977年   2篇
  1976年   3篇
  1972年   2篇
  1971年   3篇
  1964年   1篇
  1962年   1篇
  1961年   1篇
  1956年   1篇
  1932年   1篇
排序方式: 共有1741条查询结果,搜索用时 0 毫秒
21.
Heart disease is the leading cause of non-cancer death in childhood cancer survivors. to determine the prevalence of subclinical cardiac dysfunction using speckle tracking and compare its results with those obtained by classical methods of assessing left ventricular function and its relationship with different factors to identify the population at higher risk. Echocardiographic assessment of left ventricular function included ejection fraction, tissue Doppler, longitudinal/circumferential strains and biochemical parameters (troponin-T and Pro-BNP) in a cohort of 57 survivors of childhood acute leukaemia with at least 10 years since diagnosis. Ventricular dysfunction was found in 5.2% of patients in M-mode (ejection fraction—EF?<?53% with a reduction in the EF?≥?10%) and in 7% of patients with Simpson’s method, compared with 21.05 and 8.8% with suboptimal global longitudinal strain (GLS) and global circumferential strain, respectively. The GLS alteration was significantly correlated with lower values of left ventricular systolic function and was associated with high tumour risk (odds ratio [OR] 13.8), cumulative doses of anthracyclines?≥?250 mg/m2 (OR 7.6) and radiotherapy (OR 7.19). Biomarkers were not useful for the diagnosis of subclinical cardiomyopathy. Good reproducibility was obtained, with an intraobserver correlation of 93.6% and an interobserver correlation of 89.2% in the GLS. The alteration of the GLS was more prevalent than the alteration in the EF and was associated with the treatment received and high tumour risk. strain imaging seems to be a powerful tool to identify an increased number of survivor with an early myocardial injury.  相似文献   
22.
AIMS: To compare the predictive value of inflammatory biomarkers and lipids for vascular and non-vascular mortality in older men. METHODS AND RESULTS: The relevance of inflammatory biomarkers and lipids for vascular and non-vascular mortality was assessed in a prospective study of 5360 men (mean age 77 years) followed for 7 years. Vascular mortality was positively associated with log C-reactive protein (lnCRP), fibrinogen and total/HDL-C (high-density lipoprotein cholesterol), and inversely associated with albumin [age adjusted hazard ratio (HR) per 2-SD higher usual level (approximately the difference between the top and the bottom thirds of the distribution): 2.09 for lnCRP; 1.70 for fibrinogen; 0.50 for albumin and 1.45 for total/HDL-C]. The associations with the inflammatory markers were attenuated after adjustment for established risk factors, including lipids [adjusted HRs: 1.86 (lnCRP); 1.44 (fibrinogen); 0.51 (albumin)], and further attenuated (and, for fibrinogen, no longer predictive) after adjustment for each other [fully adjusted HRs: 1.60 (lnCRP); 1.01 (fibrinogen); 0.61 (albumin)]. Higher CRP and lower albumin levels were also associated with significantly raised non-vascular mortality independently of other characteristics [fully adjusted HRs: 1.62 (lnCRP); 0.65 (albumin)]. CONCLUSION: In this cohort of older men, higher CRP and lower albumin levels strongly predicted both vascular and non-vascular mortality, independently of other characteristics.  相似文献   
23.
24.
25.
The infrequency of translocations in myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemias (CMML) makes their identification and reporting interesting for the recognition of the recurrent ones and the genes involved in these neoplasias. The aims of this study were to identify new translocations associated with MDS and CMML and to establish their frequency in a cohort of 8,016 patients from the Spanish Group of MDS database. The karyotype was evaluable in 5,654 (70%) patients. Among those, 2,014 (36%) had chromosomal abnormalities, including 213 (10%) translocations identified in 195 patients. The translocations were balanced in 183 (86%) cases and unbalanced in 30 (14%) cases. All chromosomes were found to be involved in translocations, with the single exception of the Y chromosome. The chromosomes most frequently involved were in decreasing frequency: 3, 1, 7, 2, 11, 5, 12, 6, and 17. Translocations were found in karyotypes as the unique chromosomal abnormality (33%), associated with another chromosomal abnormality (11%), as a part of a complex karyotype (17%), and as a part of a monosomal karyotype (38%). There were 155 translocations not previously described in MDS or CMML and nine of them appeared to be recurrent. © 2013 Wiley Periodicals, Inc.  相似文献   
26.
27.
28.
Objective: To evaluate long-term outcomes in patients maintaining a nevirapine (NVP)-based regimen. Methods: Retrospective, multicenter, cohort study including patients currently receiving an NVP regimen that had been started at least 5 years previously. Demographic, clinical, and analytical variables were recorded. Results: Median follow-up was 8.9 (5.7-11.3) years. Baseline characteristics: 74% men, 47 years old, 36% drug users, 40% AIDS, 40% HCV+, 51.4% detectable HIV-1 viral load, CD4 count 395 (4-1,421)/μL, 19% CD4 < 200/μL, 27% ALT grade 1-2, 36% AST grade 1-2. Thirty percent ART-naive, 83%received NVP associated with 2 nucleoside analogues during the study period, and 17% a protease inhibitor. A significant improvement was observed in general health status markers, including hemoglobin, platelets, and albumin, regardless of HCV coinfection. CD4 cell gain was +218 and +322/μL after 6 and 9 years, respectively (+321 and +391 in naive patients). Triglycerides significantly decreased in pretreated patients, whereas the percentage of patients with HDLc < 1.03 mmol/L and LDL-c > 3.37 mmol/L significantly decreased in a subsample with available values. A significant decrease in transaminases, alkaline phosphatase, and Fib4 score was observed, mainly in HCV+ and ARV-naive patients. Conclusions: In patients who tolerate NVP therapy, (even those with HCV coinfection), long term benefits may be significant in terms of a progressive improvement in general health status markers and CD4 response, a favorable lipid profile, and good liver tolerability.  相似文献   
29.
30.
A series of novel 1-(N-indolyl)-1,3-butadienes, as (1 : 1) mixtures of the (E) and (Z) dienes, was prepared in one step by base-catalysed isomerization of N-alkylindoles with a terminal butyne chain. The reaction conditions are mild, and in all cases the yields were very high (>90%). The (E) and (Z) dienes were separable by preparative TLC and could be fully characterized. This isomerization proceeded readily in the case of a butynyl chain, but didn''t take place with a pentynyl chain. A mechanism was proposed for this reaction, based on previous studies on the isomerization of alkynes in basic media, and a key intermediate that supports the proposed mechanism could be isolated and fully characterized. A theoretical study of the proposed mechanism was performed by computational methods and the results validated the proposal. The reactivity of the synthesized dienes was studied in Diels–Alder reactions with p-benzoquinone, to obtain a small library of new 5-(N-indolyl)-1,4-naphthoquinones.The lack of reactivity in the case of the (Z) isomers was explained by calculation of the rotational curves of the central bond of the (Z) and (E) dienes. Finally, the cytotoxicity of the new 5-(N-indolyl)-1,4-naphthoquinones was tested against a panel of three cell lines.

A series of novel 1-(N-indolyl)-1,3-butadienes, was easily prepared in one step and used for the synthesis of 5-(N-indolyl) naphthoquinones.  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