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   1854篇
  免费   140篇
  国内免费   18篇
耳鼻咽喉   16篇
儿科学   48篇
妇产科学   19篇
基础医学   250篇
口腔科学   199篇
临床医学   168篇
内科学   409篇
皮肤病学   38篇
神经病学   140篇
特种医学   56篇
外科学   152篇
综合类   7篇
预防医学   310篇
眼科学   32篇
药学   103篇
中国医学   20篇
肿瘤学   45篇
  2023年   15篇
  2022年   25篇
  2021年   57篇
  2020年   45篇
  2019年   51篇
  2018年   53篇
  2017年   61篇
  2016年   41篇
  2015年   73篇
  2014年   71篇
  2013年   114篇
  2012年   135篇
  2011年   152篇
  2010年   83篇
  2009年   70篇
  2008年   105篇
  2007年   129篇
  2006年   81篇
  2005年   77篇
  2004年   79篇
  2003年   56篇
  2002年   45篇
  2001年   41篇
  2000年   34篇
  1999年   28篇
  1998年   23篇
  1997年   19篇
  1996年   22篇
  1995年   16篇
  1994年   19篇
  1993年   10篇
  1992年   17篇
  1991年   10篇
  1990年   5篇
  1989年   13篇
  1988年   14篇
  1987年   14篇
  1986年   7篇
  1985年   4篇
  1984年   8篇
  1983年   7篇
  1982年   7篇
  1980年   8篇
  1979年   4篇
  1972年   8篇
  1970年   4篇
  1969年   7篇
  1968年   9篇
  1966年   6篇
  1965年   3篇
排序方式: 共有2012条查询结果,搜索用时 15 毫秒
1.
SETTING: Tuberculosis (TB) cases reported from nine districts of Madrid, where the percentage of immigrant population varied from 1.9% in 1996 to 12.2% in 2003. OBJECTIVE: To describe the trends in TB incidence from 1994 to 2003. DESIGN: Observational study. RESULTS: Between 1994-1995 and 2002-2003, the TB rate decreased from 48.5 (95% CI 45.8-51.1) to 23.3 per 100000 population (95% CI 21.5-25.1) (P < 0.001). The percentage of TB cases co-infected with HIV decreased from 55.9% in 1994 to 14.3% in 2003 (P < 0.001), whereas TB cases in foreigners increased from 2.6% in 1994 to 33.7% in 2003 (P < 0.001). CONCLUSION: Although the TB rates showed a marked decrease in the study period, the increasing impact of immigration contributed to slowing down the trend.  相似文献   
2.
3.
Abstract Bleeding on probing (BOP) and the gingival index have been used to clinically characterize the degree of gingival inflammation. It is, however, unclear to what extent these parameters correlate to each other and to probing pocket depth (PD). The purpose of this clinical study was to evaluate the association between BOP and GI bleeding (scores of 2 and 3), as well as the relationship of these variables to PD, in a group of patients presenting with naturally-occurring gingivitis. Based on screening examinations of 125 subjects with at least 20 teeth, no more than 4 sites with PD over 6 mm, a BOP frequency of 30% or greater, and no systemic condition that would influence the inflammatory response, were selected. 2 weeks after screening they were examined at 6 sites per tooth for plaque index, GI, PD and BOP. A standardized pressure sensitive probe (Florida Probe) with 20 g probing force was used for BOP and PD measurements. In this population, means of 40.9% (S.E.= 1.36) BOP sites and 35.3% (S.E, = 1.81) GI bleeding sites per patient were found. A total of 20,008 sites ranging in PD up to 5.9 mm were evaluated; however, the majority of sites (19,723, 98.6%) presented with <4 mm PD. When sites were evaluated, BOP demonstrated a positive correlation with PD, whereas GI bleeding correlated with PH. For sites characterized by the absence of BOP as well as the absence of GI bleeding (scores 0 and 1), the highest % of agreement between the 2 indices (77.7%) was found in shallow sites (0.1–2 mm). In contrast, when sites presenting with both BOP and GI bleeding were analyzed, the highest % of agreement (85,4%) was found for sites with PD >4.0 mm. In this gingivitis population group, it appears that BOP and GI bleeding evaluate distinct inflammatory1 conditions of the gingival tissues, and the relationship between the 2 clinical parameters may vary according to PD at the individual site examined.  相似文献   
4.
Multiple structural and functional imaging modalities are available to localize the epileptogenic focus. In pre-surgical evaluation of children with pharmacoresistant epilepsy, investigations with the maximum yield should be considered in order to reduce the complexity of the workup. OBJECTIVE: To determine the extent to which PET, ictal/interictal SPECT and its co-registration with the patient's MRI contributes to correct localization of the epileptogenic focus, surgical intervention and to the post surgical outcome in paediatric patients. METHODS: The study population included children and adolescents with pharmacoresistant epilepsy (n = 50) who underwent preoperative evaluation, surgery and had postoperative follow-up for at least 12 months. Outcome was measured by postoperative seizure frequency using Engel's classification. RESULTS: Thirty-nine patients (78%) became completely seizure free after surgical intervention. The likelihood to benefit from surgical treatment was significantly higher if localization with more imaging modalities (MRI, PET, SPECT) were concordant with respect to the resected brain area (p < 0.01). Preoperative PET examination provided better localizing information in patients with extratemporal epilepsy and/or dysplastic lesions, whereas SPECT was found to be superior to PET in patients with temporal lobe epilepsy and/or tumors (p < 0.05). No significant difference was noted in the surgical outcome in younger or older age group, in children with or without special education needs. CONCLUSION: In paediatric epilepsy pre-surgical evaluation, the combined use of multiple functional imaging modalities for a precise localisation of the epileptogenic focus is worthwhile for both extratemporal and temporal lobe epilepsy, also when EEG and MRI alone are non-contributive, given the potential benefit of complete postoperative seizure control.  相似文献   
5.
6.
7.
We have performed restriction fragment length polymorphism (RFLP) analysis at the low density lipoprotein receptor (LDLR) locus in order to investigate the molecular genetics of familial hypercholesterolemia (FH) in Spain. Firstly, a sample of 50 unrelated patients with a clinical diagnosis of FH was screened for the presence of major rearrangements at this locus by Southern blot analysis of Bgt II digested genomic DNA. Four different mutations were detected, accounting for 8% of the mutant alleles in the Spanish FH sample. Then, we determined the relative allele frequency and estimated linkage disequilibrium between seven RFLPs of the LDLR gene in the remaining 46 FH patients and in 61 normolipidemic controls. Hindi, Avail, Pvu II, Msp I, and Nco I are the most polymorphic sites with individual PIC values higher than 0.28, whereas the Taq I and Stu I sites display low levels of polymorphism. The usefulness of the seven RFLPs to confirm a clinical diagnosis of FH was investigated in 15 FH-families, consisting of 118 individuals, in whom the presence of Familial Defective Apolipoprotein B-100 (FDB) due to the apoB3500 mutation was excluded. Independent haplotypes were constructed for 71 chromosomes: 15 FH and 56 control haplotypes. A total of 14 different haplotypes was found. In 12 families, clinical diagnosis of FH was confirmed by cosegregation analysis, which makes these RFLPs useful for studying the inheritance of the LDLR gene in 80% of Spanish families with FH. Comparison of haplotypes found in the Spanish sample with those found in Swiss and Norwegians suggests heterogeneity of haplotypes among European populations.  相似文献   
8.
9.
Streptococcus pneumoniae is the major cause of bacterial meningitis. We report a case of meningitis due to a mixed infection with two distinct strains of S. pneumoniae: one penicillin-resistant strain of serotype 9V and one penicillin-susceptible strain of serotype 7. The two strains exhibited different pulsed-field gel electrophoresis profiles.  相似文献   
10.
Genetic alterations in the rpoB gene were characterized in 50 rifampin-resistant (Rif(r)) clinical isolates of Mycobacterium tuberculosis complex from Spain. A rapid PCR-enzyme-linked immunosorbent assay (ELISA) technique for the identification of rpoB mutations was evaluated with isolates of the M. tuberculosis complex and clinical specimens from tuberculosis patients that were positive for acid-fast bacilli (AFB). Sequence analysis demonstrated 11 different rpoB mutations among the Rif(r) isolates in the study. The most frequent mutations were those associated with codon 531 (24 of 50; 48%) and codon 526 (11 of 50; 22%). Although the PCR-ELISA does not permit characterization of the specific Rif(r) allele within each strain, 10 of the 11 Rif(r) genotypes were correctly identified by this method. We used the PCR-ELISA to predict the rifampin susceptibility of M. tuberculosis complex organisms from 30 AFB-positive sputum specimens. For 28 samples, of which 9 contained Rif(r) organisms and 19 contained susceptible strains, results were concordant with those based on culture-based drug susceptibility testing and sequencing. Results from the remaining two samples could not be interpreted because of low bacillary load (microscopy score of 1+ for 1 to 9 microorganisms/100 fields). Our results suggest that the PCR-ELISA is an easy technique to implement and could be used as a rapid procedure for detecting rifampin resistance to complement conventional culture-based methods.  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