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   11253篇
  免费   1260篇
  国内免费   165篇
耳鼻咽喉   63篇
儿科学   3956篇
妇产科学   507篇
基础医学   772篇
口腔科学   109篇
临床医学   1311篇
内科学   658篇
皮肤病学   67篇
神经病学   307篇
特种医学   128篇
外科学   502篇
综合类   1480篇
现状与发展   3篇
预防医学   1998篇
眼科学   124篇
药学   535篇
  7篇
中国医学   108篇
肿瘤学   43篇
  2024年   23篇
  2023年   172篇
  2022年   238篇
  2021年   528篇
  2020年   441篇
  2019年   477篇
  2018年   360篇
  2017年   471篇
  2016年   458篇
  2015年   465篇
  2014年   632篇
  2013年   781篇
  2012年   691篇
  2011年   659篇
  2010年   495篇
  2009年   463篇
  2008年   482篇
  2007年   615篇
  2006年   563篇
  2005年   462篇
  2004年   368篇
  2003年   292篇
  2002年   279篇
  2001年   227篇
  2000年   214篇
  1999年   167篇
  1998年   171篇
  1997年   142篇
  1996年   159篇
  1995年   116篇
  1994年   142篇
  1993年   86篇
  1992年   92篇
  1991年   67篇
  1990年   83篇
  1989年   65篇
  1988年   69篇
  1987年   45篇
  1986年   51篇
  1985年   69篇
  1984年   46篇
  1983年   32篇
  1982年   49篇
  1981年   24篇
  1980年   28篇
  1979年   18篇
  1978年   20篇
  1977年   18篇
  1976年   16篇
  1971年   7篇
排序方式: 共有10000条查询结果,搜索用时 437 毫秒
31.
强化婴幼儿奶粉中叶酸的测定   总被引:1,自引:0,他引:1  
强化叶酸的奶粉在0.05M K_2HPO_4缓冲液中,经均质,调pH4.5,15000g离心20分钟,其清液调pH4.0,进行CGS树脂离子交换层析,用10ml KClK_2HPO_4洗脱,调pH7.0,进行HPLC测定,采用300x3.9mm ODS反相柱,移动相0.05M K_2HPO+MeOH(91+9),流速1ml/分,紫外检测器波长285nm,灵敏度0.0050D。方法相对标准偏差为±3.3%,回收率为87%,最小检测量为0.02μg/ml。  相似文献   
32.
Infants living in an orphanage (n = 22) in Romania were assessed on the Test of Sensory Functions in Infants (TSFI). Testing of the institutionalized infants was done before and 6 months after an enriched caregiver intervention program. Results showed significant changes in areas of reactivity to tactile deep pressure, visual-tactile integration, oculomotor control, reactivity to vestibular stimulation and total test responses. No significant changes occurred in the area of adaptive motor functions. Effects of sensory deprivation resulting from institutional settings and changes that can occur from enriched caregiver environments are discussed.  相似文献   
33.
34.
Early catch-up growth and subsequent overweight are suggested to be associated with later cardiovascular diseases and later type II diabetes. However, the impact of early catch-up growth and childhood overweight on the development of asthma has been less studied, particularly in children born with very low birth weight (VLBW). A birth cohort of 74 VLBW children (birth weight < or = 1500 g) was followed from birth and investigated on asthma at 12 yr of age. Early rapid weight gain was in one way defined as an increase of weight > or =1 standard deviation score (SDS) at 6 months of corrected postnatal age. Current overweight was defined by body mass index (BMI) exceeding 21.2 and 21.7 kg/m(2), respectively, for boys and girls at 12 yr of age. Current asthma was diagnosed by a pediatrician, according to asthma ever in combination with a positive response to hypertonic saline bronchial provocation test and/or wheeze at physical examination at 12 yr old. Being overweight at 12 yr of age was associated with an increased risk for current asthma in the VLBW children [crude odds ratio (OR): 5.5, 95% confidence interval (CI): 1.3-22.2]. After adjustment for early weight gain and neonatal risk, the OR of overweight increased nearly three times (adjusted OR: 15.3, 95% CI: 2.5-90.6). Early rapid weight gain seemed to be inversely associated with current asthma (adjusted OR: 0.49 for an increase of weight equal to 1 SDS, 95% CI: 0.23-1.02, p = 0.06). In addition, early rapid weight gain was inversely associated with the magnitude of bronchial responsiveness at 12 yr (coefficient -1.15, p < 0.01). There was a strong and positive association between overweight and asthma at 12 yr of age in the VLBW children. This strong association had been reduced by early rapid weight gain, possibly via the reduction of bronchial responsiveness.  相似文献   
35.
OBJECTIVE: To explore pregnancy outcome in HIV-1-positive and HIV-negative women, and mother-to-child transmission (MTCT) according to mode of delivery under effective highly active antiretroviral therapy (HAART). DESIGN: Cohort of 143 pregnant HIV-1-infected women including a matched case-control study in a 2:1 ratio of controls to cases (n=98). SETTING: Academic Medical Center in Amsterdam and Erasmus Medical Center in Rotterdam, the Netherlands. POPULATION: Consecutive referred HIV-1 infected pregnant women treated with HAART and matched control not infected pregnant women. MAIN OUTCOME MEASURES: MTCT, preterm delivery, low birthweight, pre-eclampsia. RESULTS: MTCT was 0% (95% CI 0-2.1%). Seventy-eight percent of HIV-1-infected women commenced and 62% completed vaginal delivery. The calculated number of caesarean sections needed to prevent a single MTCT was 131 or more. Preterm delivery rates were 18% (95% CI 11-27) in women infected with HIV-1 and 9% (95% CI 5-13) in controls (P=0.03). HAART used at <13 weeks of gestation was associated with a 44% preterm delivery rate compared with 21% when HAART was started at or after 13 weeks and 14% in controls. (Very) low birthweight and incidence of pre-eclampsia were not different between HIV-1 and controls. CONCLUSIONS: We have not demonstrated any MTCT after vaginal delivery in women effectively treated by HAART. The HAART-associated increase in preterm delivery rate is mainly seen after first trimester HAART use.  相似文献   
36.
There are more than 40 H(1)-antihistamines available worldwide. Most of these medications have never been optimally studied in prospective, randomized, double-masked, placebo-controlled trials in children. The aim was to perform a long-term study of levocetirizine safety in young atopic children. In the randomized, double-masked Early Prevention of Asthma in Atopic Children Study, 510 atopic children who were age 12-24 months at entry received either levocetirizine 0.125 mg/kg or placebo twice daily for 18 months. Safety was assessed by: reporting of adverse events, numbers of children discontinuing the study because of adverse events, height and body mass measurements, assessment of developmental milestones, and hematology and biochemistry tests. The population evaluated for safety consisted of 255 children given levocetirizine and 255 children given placebo. The treatment groups were similar demographically, and with regard to number of children with: one or more adverse events (levocetirizine, 96.9%; placebo, 95.7%); serious adverse events (levocetirizine, 12.2%; placebo, 14.5%); medication-attributed adverse events (levocetirizine, 5.1%; placebo, 6.3%); and adverse events that led to permanent discontinuation of study medication (levocetirizine, 2.0%; placebo, 1.2%). The most frequent adverse events related to: upper respiratory tract infections, transient gastroenteritis symptoms, or exacerbations of allergic diseases. There were no significant differences between the treatment groups in height, mass, attainment of developmental milestones, and hematology and biochemistry tests. The long-term safety of levocetirizine has been confirmed in young atopic children.  相似文献   
37.
Adrenocortical responsiveness was assessed in eight very low birthweight neonates who had bronchopulmonary dysplasia and had been weaned from mechanical ventilation using dexamethasone. Three of the eight infants did not respond to ACTH stimulation during the first week after cessation of dexamethasone, but all three responded normally when retested at least 1 month later. The present authors have thus demonstrated that some infants have at least temporary adrenocortical unresponsiveness after prolonged courses of glucocorticoid therapy, and suggest that adrenocortical function should be assessed in all infants who are weaned from mechanical ventilation using dexamethasone.  相似文献   
38.
BACKGROUND: Higher house dust mite (HDM) allergen exposure during infancy has been associated with increased HDM sensitization. Infant bedding has been associated with the accumulation of varying levels of HDM. Prospective data on the relationship between infant bedding and the development of HDM sensitization has not been previously examined. OBJECTIVES: To determine if particular types of bedding used in infancy are associated with increased risk of house dust mite sensitization in childhood. METHODS: A population-based sample (n = 498) of children born in 1988 or 1989, and who were resident in Northern Tasmania in 1997, participated in this study. These children were part of a birth cohort study (1988-95), the Tasmanian Infant Health Survey. Data on infant underbedding and mattresses was available on 460 and 457 children, respectively. The main outcome measure was HDM sensitization defined as a skin prick test (SPT) reaction of 3 mm or more to the allergens of Dermatophagoides pteronyssinus and/or Dermatophagoides farinae. RESULTS: The use of either sheepskin underbedding or plastic mattress covers in infancy was associated with an increased risk of sensitization to HDM allergens at age 8 years. The adjusted risk ratio (RR) for sensitization to HDM with sheepskin in infancy was 2.27 (95% CI: 1.14, 4.55), P = 0.020. The adjusted RR for sensitization to HDM with the use of plastic mattress covers in infancy was 2.06 (95% CI: 1.22, 3.51), P = 0.007. The use of a foam mattress in infancy was not related to subsequent HDM sensitization. CONCLUSION: Infant's bedding plays a role in the development of HDM sensitization in childhood. Intervention studies to examine mite allergen levels and the role of underbedding on the development of HDM sensitization are required.  相似文献   
39.
预防婴幼儿急腹症手术合并急性心衰的护理   总被引:1,自引:1,他引:0  
目的 提高对心衰合并急性肺水肿的认识,加强针对性的护理,避免延误抢救治疗时间。方法 搜集2001年1月至2003年9月在我院婴幼儿急腹症手术婴幼儿急腹症手术前后出现的急性心衰并肺水肿共33例。通过对并发急性心衰合并肺水肿的婴幼儿进行的手术护理的病例分析;对患儿术前、术中和术后三个不同阶段的观察和护理。结果 经治疗后患儿急性心衰及肺水肿很快被控制。特别是早发现、早治疗的患儿。治愈29例,自动出院1例,死亡3例。结论 对婴幼儿急腹症手术加强心率、呼吸等体征的观察,及早作出急性心衰、肺水肿的诊断及处理,分秒必争,有效地防治心衰的发生,是抢救成功的重要措施之一。  相似文献   
40.
对贵阳市1500名健康婴幼儿童和青少年进行骨发育的调查,根据手腕部骨X线解剖变化规律,观察每块骨从出现至成熟的过程中,骨化点的出现顺序、数量、形态和密度的改变等指标的系列变化,提出了骨发育评价标准。可供我省运动员选材、儿童少年发育咨询和临床治疗参考。  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