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   4512篇
  免费   137篇
  国内免费   18篇
耳鼻咽喉   10篇
儿科学   333篇
妇产科学   929篇
基础医学   474篇
口腔科学   10篇
临床医学   244篇
内科学   234篇
皮肤病学   33篇
神经病学   373篇
特种医学   16篇
外科学   102篇
综合类   351篇
预防医学   1188篇
眼科学   2篇
药学   328篇
  3篇
中国医学   21篇
肿瘤学   16篇
  2023年   74篇
  2022年   161篇
  2021年   196篇
  2020年   209篇
  2019年   183篇
  2018年   147篇
  2017年   156篇
  2016年   165篇
  2015年   161篇
  2014年   300篇
  2013年   368篇
  2012年   250篇
  2011年   304篇
  2010年   187篇
  2009年   247篇
  2008年   214篇
  2007年   211篇
  2006年   164篇
  2005年   115篇
  2004年   97篇
  2003年   70篇
  2002年   63篇
  2001年   39篇
  2000年   38篇
  1999年   23篇
  1998年   30篇
  1997年   28篇
  1996年   18篇
  1995年   31篇
  1994年   22篇
  1993年   26篇
  1992年   29篇
  1991年   21篇
  1990年   14篇
  1989年   17篇
  1988年   9篇
  1986年   9篇
  1985年   30篇
  1984年   30篇
  1983年   28篇
  1982年   38篇
  1981年   22篇
  1980年   20篇
  1979年   15篇
  1978年   17篇
  1977年   18篇
  1976年   13篇
  1975年   10篇
  1974年   9篇
  1973年   9篇
排序方式: 共有4667条查询结果,搜索用时 15 毫秒
81.
BackgroundThe development of allo-anti-Rh17 (anti-Hr0) in a −D– phenotype whose red blood cells (RBCs) lack CcEe antigens is most likely triggered by transfusion, transplantation, or pregnancy. Gene conversion is the predominating factor in generating RHD-CE-D and RHCE-D-CE hybrids like −D–.MethodsWe report here immunohematological and obstetrical data from 2 of the 5 pregnancies of a 24-year-old woman presenting with the −D– phenotype with anti-Rh17. Blood group typing, antibody screening, antibody differentiation, direct antiglobulin test (DAT), and antibody titers were performed by routine gel technology and tube testing. Additionally, molecular genetic analysis was performed. Fetal surveillance was done by sonographic evaluation of the fetal middle cerebral artery peak systolic velocity (MCA-PSV).ResultsBlood group typing showed O, C-c-D+E-e- and the DAT was negative. DNA sequencing revealed homozygosity for an RHCE-D(3–9)-CE null allele. Anti-Rh17 titers in the fourth pregnancy remained between 1:8 and 1:128, and no signs for a fetal anemia were observed. However, in the fifth pregnancy, the antibody titers increased up to 1:4,096. Signs of moderate fetal anemia were detected and cesarean section was performed at 34 + 6 weeks of gestation. The newborn presented with hemolytic anemia (cord blood hemoglobin [Hb] = 8.5 mg/dL). She received 2 compatible (small) packed RBC concentrates, phototherapy, and intravenous immunoglobulins.ConclusionOur case shows that the risk for hemolytic complications increases with the number of pregnancies of sensitized women. Only people who also lack CcEe antigens are compatible as donors. The role of such rare donors as lifesavers, their freedom, and voluntariness conflict with the urgent need for compatible blood.  相似文献   
82.
肖敏  陶瑞雪  张燕 《安徽医药》2020,41(5):526-529
目的 探讨瘢痕子宫孕妇不同分娩方式的选择以及对母儿结局的影响。方法 选择2017年1月至2018年12月在合肥市第一人民医院产科住院且符合剖宫产后阴道试产纳入标准的产妇160例,依据医生评估结果及产妇意愿选择分娩方式,按实际分娩结果分为剖宫产后阴道分娩(简称阴道分娩)组68例,再次剖宫产(简称剖宫产)组80例,12例因阴道试产失败急诊行子宫下段剖宫产术(简称阴道试产失败组)。同时选择同期住院分娩的40例单胎顺产初产妇作为对照组。比较各组产妇的临床特征以及分娩信息,分析影响瘢痕子宫产妇阴道试产成功的相关因素。结果 在瘢痕子宫患者中,阴道分娩成功率为85%。阴道分娩组与阴道试产失败组相比,孕妇体质量、体质量指数、距上次剖宫产时间、新生儿体质量、产时出血量、产后24 h出血量差异均有统计学意义(P<0.05),而孕妇年龄、孕次、产次、瘢痕厚度、新生儿Apgar评分差异无统计学意义(P>0.05)。阴道分娩组孕妇体质量、体质量指数、孕周、距上次剖宫产时间、新生儿体质量、产后24 h出血量、住院时间均小于剖宫产组,差异有统计学意义(P<0.05),孕妇年龄、孕次、产次、瘢痕厚度、新生儿Apgar评分差异均无统计学意义(P>0.05)。阴道分娩组与对照组相比,分娩时出血量、产后24 h出血量、新生儿Apgar评分、产后住院时间差异均无统计学意义(P>0.05)。结论 瘢痕子宫孕妇在严格的操作规程以及孕期控制体质量指数、胎儿体质量可鼓励阴道试产。  相似文献   
83.
The aim of this study is to determine the fetus Y-STR haplotype in maternal plasma during pregnancy and estimate, non-invasively, if the alleged father and fetus belong to the same male lineage. The study enrolled couples with singleton pregnancies and known paternity. All participants signed informed consent and the local ethics committee approved the study. Peripheral blood was collected in EDTA tubes (mother) and in FTA paper (father). Maternal plasma DNA was extracted by using NucliSens EasyMAG. Fetal gender was determined by qPCR targeting DYS-14 in maternal plasma and it was also confirmed after the delivery. From all included volunteers, the first consecutive 20 mothers bearing male fetuses and 10 mothers bearing female fetuses were selected for the Y-STR analysis. The median gestational age was 12 weeks (range 12–36). All DNA samples were subjected to PCR amplification by PowerPlex Y23, ampFLSTR Yfiler, and two in-house multiplexes, which together accounts for 27 different Y-STR. The PCR products were detected with 3500 Genetic Analyzer and they were analyzed using GeneMapper-IDX. Fetuses’ haplotypes (Yfiler format) were compared to other 5328 Brazilian haplotypes available on Y-chromosome haplotypes reference database (YHRD). As a result, between 22 and 27 loci were successfully amplified from maternal plasma in all 20 cases of male fetuses. None of the women bearing female fetuses had a falsely amplified Y-STR haplotype. The haplotype detected in maternal plasma completely matched the alleged father haplotype in 16 out of the 20 cases. Four cases showed single mismatches and they did not configure exclusions; 1 case showed a mutation in the DYS 458 locus due to the loss of one repeat unit and 3 cases showed one DYS 385I/II locus dropout. All mismatches were confirmed after the delivery. Seventeen fetuses’ haplotypes were not found in YHRD and one of them had a mutation, which corresponded to the paternity probability of 99.9812% and 95.7028%, respectively. Three fetuses’ haplotypes occurred twice in YHRD, which corresponded to paternity probability of 99.9437%. In conclusion, high discriminatory fetal Y-STR haplotype could be determined from maternal plasma during pregnancy starting at 12 weeks of gestation. All male fetuses could be attributed to the alleged father male lineage early in pregnancy. The high probability of paternity associated with each case suggests that the relationship is not random and this strategy can be use as an alternative for male fetal kinship analysis.  相似文献   
84.
The present study examined the effects of coping styles, social support, and child's behavioral symptoms on the well-being of 65 mothers of children with Autism Spectrum Disorders (ASD) in Lebanon. Comparisons to the well-being of 98 mothers of typically developing children were also drawn. Regression analyses showed that disengagement and distraction coping predicted poor well-being, whereas cognitive reframing showed a correlation with better well-being levels. A significant correlation was found between child's behavioral problems and maternal well-being. T-test analyses revealed that mothers of children with ASD differed in terms of coping styles used. Additionally, mothers of children with ASD showed lower levels of perceived social support. Well-being was significantly better for mothers of typically developing children. Study limitations and implications are discussed.  相似文献   
85.
86.
87.

Objectives

To ascertain the prevalence, presentation, diagnosis, severity, and complications of HELLP syndrome.

Materials and Methods

This is a prospective observational study analyzing the conditions and the data of 24 cases of HELLP syndrome in a tertiary care hospital. The analysis was done for the demographic characteristics, presentation of these patients, complications associated, and the perinatal outcome.

Results

0.45 % of the patients admitted for delivery developed HELLP syndrome. Majority of the patients developed the condition in 30–36 weeks period of gestation, while five patients developed it in the postpartum period. The condition led to 12.5 % of maternal and 45.8 % of perinatal mortality.

Conclusion

HELLP syndrome is an important cause for maternal and perinatal morbidity and mortality.  相似文献   
88.

Objective:

This study is to determine the pattern of overweight and obesity and its relationship with childhood anthropometric status in Nigeria.

Materials and Methods:

This cross-sectional study was conducted in Jos, Nigeria. Interviewer administered questionnaire was used in data collection. Maternal and child anthropometric measurements were obtained using standard WHO methods. Child anthropometric Z scores were obtained from WHO Anthroplus while BMI of mothers were also determined. Totally, 262 mother-child pairs were recruited.

Results:

Mean maternal age and mean child age were 30.8 ± 6.3 yrs (15-47 yrs) and 22.3 ± 18.7 months (3-72 months). Prevalence of maternal underweight, overweight and obesity was 4.2% (11/262), 29.4% (77/262) and 25.9% (68/262), respectively. Child overweight/obesity was 5.4% (14/262), severe under-nutrition 5.7% (15/262). Mean maternal BMI was higher in the older, more educated and higher socioeconomic status (SES). Child mean birth-weight, weight-for-age Z-score and BMI-for-age Z-score (BAZ) were higher among mothers with BMI ≥ 25 kg/m2. All large-for-age babies were in mothers with maternal BMI ≥ 25 kg/m2. Childhood over-nutrition was more common in maternal BMI of ≥25 kg/m2. Overall, BAZ was directly related with maternal BMI, maternal age and birth-weight, although it was inversely related with maternal BM I ≥ 25 kg/m2.

Conclusion:

Higher BMI is seen in educated and higher SES mothers and this impact on childhood anthropometry.  相似文献   
89.
作为一种重要的生命早期刺激方式, 出生后至断乳前的母婴分离刺激已被证实在成年后能够模拟肠易激综合征胃肠道症状及精神症状。利用母婴分离建立的肠易激动物模型, 因其同时模拟了肠易激综合征中枢精神症状及外周胃肠道症状成为当前研究肠易激综合征生物学机制的一个常用模型。文章综合整理母婴分离对啮齿类动物神经发育及胃肠道发育的影响,对该模型运用于研究肠易激综合征机制的进展稍作总结,以表明母婴分离可以模拟大部分肠易激综合征的外周及中枢表现,证实了该模型模拟脑肠轴异常造成的肠易激综合征的可行性,为采用该模型进行肠易激综合征相关研究提供一定的理论支持。  相似文献   
90.
BackgroundFemale patients with rheumatoid arthritis (RA) can have successful pregnancies. However, those who experience a higher disease activity during pregnancy and require continued treatment have a potential risk of maternal and neonatal complications.Aim of the workTo assess pregnancy outcome (adverse maternal and neonatal outcomes) in an Egyptian cohort of female RA patients.Patients and methodsThiscross-sectional study involved 200 female RA patients and 100 healthy age-matched controls. All were subjected to detailed gynecological history including: number of pregnancies, miscarriage, mode of delivery, maternal complication (gestational diabetes and preeclampsia), fetal complication (prematurity, low birth weight ‘LBW’ and congenital anomalies) and medicationsused during pregnancy. The disease activity score (DAS28) was assessed pre-conception and in each trimester.ResultsPatients had significantly lower number of pregnancies (p = 0.002) and deliveries (p = 0.001) and higher incidence of miscarriages (p = 0.022) compared to controls. Delivery by Cesarean section (CS) was higher inpatients (p = 0.001) with an increased risk of preeclampsia (p = 0.042). Both the antenatal and natal DAS28 significantly correlatedwith abortions, deliveries by CS and LBW (p = 0.005, p = 0.004 and p < 0.001, respectively). Pre-conceptional methotrexate use significantly correlated with the number of abortions (p = 0.02). Corticosteroid use during pregnancy was related to LBW of newborns (p = 0.03).ConclusionPregnant RA patients have higher frequency of abortion, delivery by CS, preeclampsia and LBW of newborns; especially those having higher disease activity and/ortreated with potentially harmful medications. It is crucial to educate female RA patients about these risks and they should be considered as high-risk pregnancy and followed accordingly.  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