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   591篇
  免费   26篇
  国内免费   2篇
耳鼻咽喉   6篇
儿科学   23篇
妇产科学   7篇
基础医学   95篇
口腔科学   21篇
临床医学   53篇
内科学   110篇
皮肤病学   10篇
神经病学   53篇
特种医学   17篇
外科学   25篇
综合类   3篇
预防医学   93篇
眼科学   6篇
药学   48篇
中国医学   6篇
肿瘤学   43篇
  2023年   4篇
  2022年   11篇
  2021年   15篇
  2020年   6篇
  2019年   15篇
  2018年   13篇
  2017年   8篇
  2016年   16篇
  2015年   13篇
  2014年   31篇
  2013年   26篇
  2012年   60篇
  2011年   61篇
  2010年   27篇
  2009年   25篇
  2008年   27篇
  2007年   39篇
  2006年   31篇
  2005年   34篇
  2004年   27篇
  2003年   34篇
  2002年   25篇
  2001年   9篇
  2000年   11篇
  1999年   4篇
  1998年   5篇
  1997年   2篇
  1996年   2篇
  1995年   3篇
  1994年   3篇
  1993年   3篇
  1992年   4篇
  1991年   3篇
  1990年   4篇
  1988年   4篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1979年   3篇
  1977年   1篇
  1970年   1篇
  1966年   1篇
  1965年   1篇
排序方式: 共有619条查询结果,搜索用时 15 毫秒
31.
OBJECTIVE: The purpose of this study was to evaluate the angiotensin-converting enzyme gene polymorphism in pregnant women with and without preeclampsia. STUDY DESIGN: Preeclampsia was defined as hypertension and pathologic proteinuria in pregnant women after gestational week 20. Genomic DNA was isolated from leukocytes. The insertion-deletion polymorphism in intron 16 of the angiotensin-converting enzyme gene was detected in DNA samples with the use of the polymerase chain reaction. Chi-squared and Student t tests were used for statistical analysis. RESULTS: In preeclampsia (n=51 women) angiotensin-converting enzyme genotypes were deletion-D (DD) in 16 women (31%), insertion-I (II) in 12 women (24%), and insertion-deletion in 23 women (45%); in the control group (n=71), the angiotensin-converting enzyme genotypes were DD in 21 women (30%), II in 17 women (24%), and insertion-deletion in 33 women (46%). Angiotensin-converting enzyme genotype distribution and allelic frequencies were not different between groups. CONCLUSION: No difference in the angiotensin-converting enzyme genotype distribution was found between preeclampsia and normal pregnancy. The results showed no association between angiotensin-converting enzyme polymorphism and the development of preeclampsia.  相似文献   
32.
The high frequency of T cell receptor gamma (TCRG) gene rearrangements in both B-lineage and T cell acute lymphoblastic leukemia (ALL), its easy detection and the lower incidence of oligoclonality make this gene one of the main target for the detection of minimal residual disease by PCR in childhood ALL. We analyzed the frequency and type of TCRG rearrangements in DNA samples obtained from the bone marrow of 102 Brazilian children at diagnosis using PCR and automatic sequencing. TCRG rearrangements were found in 69% of patients with B-lineage ALL and in 94% of patients with T cell ALL. In contrast to other studies, rearrangements involving the Vgamma9 segment reported to be uncommon were the most frequent both in B-lineage and T cell ALL and involved 49/109 (45%) of the rearranged alleles. This fact should be considered when standardizing consensus primers for the study of minimal residual disease in different populations.  相似文献   
33.
Neuroendocrine aspects of chronic fatigue syndrome   总被引:1,自引:0,他引:1  
Chronic fatigue syndrome (CFS) is a serious health concern affecting over 800000 Americans of all ages, races, socioeconomic groups and genders. The etiology and pathophysiology of CFS are unknown, yet studies have suggested an involvement of the neuroendocrine system. A symposium was organized in March 2001 to explore the possibility of an association between neuroendocrine dysfunction and CFS, with special emphasis on the interactions between neuroendocrine dysfunction and other abnormalities noted in the immune and autonomic nervous systems of individuals with CFS. This paper represents the consensus of the panel of experts who participated in this meeting.  相似文献   
34.

Background  

Chronic fatigue syndrome (CFS) is a debilitating illness with no known cause or effective therapy. Population-based epidemiologic data on CFS prevalence are critical to put CFS in a realistic context for public health officials and others responsible for allocating resources.  相似文献   
35.

Background  

Chronic fatigue syndrome (CFS) has no diagnostic clinical signs or diagnostic laboratory abnormalities and it is unclear if it represents a single illness. The CFS research case definition recommends stratifying subjects by co-morbid conditions, fatigue level and duration, or functional impairment. But to date, this analysis approach has not yielded any further insight into CFS pathogenesis. This study used the integration of peripheral blood gene expression results with epidemiologic and clinical data to determine whether CFS is a single or heterogeneous illness.  相似文献   
36.
This work has evaluated the temperature effect in the production of multiple xylanases by a locally isolated strain of Aspergillus fumigatus Fresenius. Three isoenzymes, identified as xylanases I, II, and III with apparent molecular weight of 45.7 KDa, 39.8 KDa and 18.2 KDa, respectively, were produced in cultures developed at 30 degrees C and at 42 degrees C. The pattern of distribution of xylanase activity among the three isoenzymes was greatly affected by the growth temperature: at 30 degrees C, the total xylanase activity was distributed homogeneously among the three enzymes, while at 42 degrees C, the total xylanase activity was mainly due to the fractions with the highest MW (I and II) and the xylanase III was a minor component.  相似文献   
37.
OBJECTIVE: To evaluate test-retest reliability of social network-related information of the" Pr -Sa de" study. METHODS: A test-retest reliability study was conducted using a multidimensional questionnaire applied to a cohort of university employees. The same questionnaire was filled out twice by 192 non-permanent employees with two weeks apart. Agreement was estimated using kappa statistics (categorical variables), weighted kappa statistics, log-linear models (ordinal variables), and intraclass correlation coefficient (discrete variables). RESULTS: Estimates of reliability were higher than 0.70 for most variables. Stratified analyses revealed no consistently varying patterns of reliability according to gender, age or schooling strata. Log-linear modelling showed that, for the study ordinal variables, the model of best fit was "diagonal agreement plus linear by linear association". CONCLUSIONS: The high level of reliability estimated in this study suggests that the process of measurement of social network-related aspects was adequate. Validation studies, which are currently being conducted, will complete the quality assessment of this information.  相似文献   
38.
39.
A case is reported of congenital cytomegalovirus infection. A baby girl was born at an estimated gestational age of 35 weeks to a 26-year-old Hispanic women. There was maternal cocaine abuse and poor prenatal care, and variable decelerations, abruptio placentae, and meconium-stained fluid occurred in the intrapartum period. Cytomegalovirus was isolated from the urine, with growth occurring in 48 hours, and the neonate had characteristic neurodevelopment handicaps.  相似文献   
40.
OBJECTIVE: To identify elements of affective instability associated with an increased likelihood of impulsivity and then to determine whether these elements characterize patients with borderline personality disorder (BPD) and suicidal behaviour. METHOD: We prospectively followed 82 individuals with BPD and a history of recurrent suicidal behaviour who recorded their current mood states, impulsivity, suicide ideation, and environmental stressors (triggers) 6 times daily over 3 weeks. RESULTS: Our results suggested that mood amplitude was correlated with impulsivity and that 4 subgroups defined by mean scores on mood amplitude and negative mood intensity significantly differed in the number of suicidal behaviours reported in the last year. CONCLUSIONS: A subgroup of BPD patients appears to be at elevated risk for suicidal behaviour based on high mood amplitude and mean negative mood intensity. Clinicians might target this group for monitoring and interventions to reduce the likelihood of suicidal behaviour.  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