首页 | 官方网站   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   1093篇
  免费   20篇
  国内免费   14篇
医药卫生   1127篇
  2023年   7篇
  2021年   15篇
  2020年   16篇
  2019年   21篇
  2018年   18篇
  2017年   20篇
  2016年   17篇
  2015年   24篇
  2014年   28篇
  2013年   37篇
  2012年   30篇
  2011年   17篇
  2010年   54篇
  2009年   43篇
  2008年   29篇
  2007年   32篇
  2006年   29篇
  2005年   32篇
  2004年   13篇
  2003年   21篇
  2002年   15篇
  2001年   13篇
  2000年   16篇
  1999年   16篇
  1998年   48篇
  1997年   47篇
  1996年   39篇
  1995年   33篇
  1994年   38篇
  1993年   32篇
  1992年   11篇
  1991年   15篇
  1990年   18篇
  1989年   25篇
  1988年   22篇
  1987年   19篇
  1986年   17篇
  1985年   12篇
  1984年   9篇
  1983年   13篇
  1982年   17篇
  1981年   15篇
  1980年   20篇
  1979年   6篇
  1977年   14篇
  1976年   12篇
  1975年   7篇
  1971年   5篇
  1970年   6篇
  1968年   5篇
排序方式: 共有1127条查询结果,搜索用时 15 毫秒
1.
Gastroesophageal reflux disease (GERD) is the most common disease of the upper gastrointestinal tract. With the introduction of proton pump inhibitors medical treatment of GERD has been significantly improved. However, the development of laparoscopic antireflux surgery resulted in an increasing interest of surgeons in this disease. An interactive meeting was organized in order to develop an agreement between gastoenterologists and surgeons regarding therapeutic decisions and this is the main topic of this paper.  相似文献   
2.
Mutations of the iduronate-2-sulfatase gene were identifiedin 16 patients with mucopolysaccharidosis type II (Hunter syndrome).Together with another 10 cases reported by us earlier it emergesthat about 20% of the patients have deletions of the whole geneor other major structural alterations. One, two or three basepair deletions are found in about 23% of the cases while theremaining about 57% carry point mutations predicting amlno acidreplacement, premature termination of translation, or aberrantsplicing. Molecular analysis of mRNA in splice site mutantsshowed that these latter defects frequently resulted in useof cryptic splice sites in exons or introns. 62% of the smalldeletions and point mutations have occurred in 3 of the 9 iduronate-2-sulfatasegene exons. Knowledge of the primary genetic defect allows fastand reliable carrier detection and prenatal diagnosis as wellas insight into the relationship between genotype and phenotype.  相似文献   
3.
OBJECTIVE: Although breastfeeding is associated with lower rates of a variety of infant illnesses, skeptics have suggested that much of the association is attributable to confounding, even after appropriate statistical adjustment. This article utilizes a novel design to investigate changes in infant illness at the community level after a successful breastfeeding promotion program. METHODS: In this population-based cohort study, the medical records of all infants born in one Navajo community the year before a breastfeeding promotion program (n = 977) and the year during the intervention (n = 858) were reviewed. Outcomes assessed include changes after the intervention in: proportion breastfeeding and/or breastfeeding exclusively; incidence of common infant illnesses in the first year of life; and feeding-group specific incidence of illness. RESULTS: The proportion of women breastfeeding exclusively for any period of time increased from 16.4% to 54.6% after the intervention. The percent of children having pneumonia and gastroenteritis declined 32. 2% and 14.6%, respectively, after the intervention. Feeding-group specific rates of these illnesses were unchanged, indicating that the decline observed was attributable to the increased proportion of infants breastfeeding. In contrast, rates of croup and bronchiolitis increased after the intervention among those fed formula from birth, suggesting a viral epidemic which was limited to those never exclusively breastfed. Finally, sepsis declined in both formula-fed and breastfed infants after the intervention, suggesting that other factors affected this illness outcome after the intervention. CONCLUSIONS: Increasing the proportion of exclusively breastfed infants seems to be an effective means of reducing infant illness at the community level. The experimental design suggests that the increased incidence of illness among minimally breastfed infants is causally related to lack of breast milk, rather than being attributable to confounding.  相似文献   
4.
5.
Intrathoracic stomach is a rare and serious congenital abnormality. The anomaly may be complicated by gastric volvulus and can lead to ischemic gastric infarction in the neonate. If diagnosed antenatally, neonatal management can be planned in advance so as to reduce morbidity. This anomaly must be differentiated from the more common congenital diaphragmatic hernia, as associated pulmonary hypoplasia is common in the latter and rare with gastric herniation. We report an infant born to a mother with Marfan's syndrome with the antenatal diagnosis of intrathoracic stomach. The ultrasound and magnetic resonance imaging features of this congenital abnormality are described. A review of the literature would indicate that this is the first case report of gastric volvulus diagnosed in utero.  相似文献   
6.
标题 a)口服左旋-Sotatol治疗心肌梗死后左室功能不全患者生存研究(SWORD):试验依据、设计和方法   b)右旋-Sotatol对亚急性和陈旧性心肌梗死后左室功能不全患者病死率的影响研究作者 WaldoAL,CammAJ,deruyterH,等a)AmJCardiol,1995,75:1023~1027b)Lancet,1996,348:7~12  研究疾病:充血性心力衰竭。目的:右旋-Sotatol为一种具有专一性钾通道阻滞作用的抗心律失常药物。本研究将对其降低心肌梗死后左室功能不全…  相似文献   
7.
Al‐Shibli K, Al‐Saad S, Andersen S, Donnem T, Bremnes RM, Busund L‐T. The prognostic value of intraepithelial and stromal CD3‐, CD117‐ and CD138‐positive cells in non‐small cell lung carcinoma. APMIS 2010; 118: 371–82. The major value of prognostic markers in potentially curable non‐small cell lung carcinoma (NSCLC) should be to guide therapy after surgical treatment. Although tumor‐infiltrating T lymphocytes and plasma cells have been documented in NSCLC, a clear association with clinical outcome, especially for the stromal component, has not been well established. The aim of this study was to elucidate the prognostic significance of these cells/markers in the epithelial and stromal compartments of NSCLC. Tissue microarrays from 335 resected, stage I‐IIIA, NSCLC were constructed by duplicate cores from viable neoplastic epithelial and stromal areas. Immunohistochemistry was used to evaluate the infiltration of CD3+, CD117+ as well as CD138+ cells in epithelial and stromal areas. In univariate analyses, increasing numbers of stromal CD3+ (p = 0.001) and epithelial CD3+ cells (p = 0.004) correlated significantly with an improved disease‐specific survival. No such relation was noted with CD3+ or CD117+ cells. In the multivariate analysis, stromal CD3+ cells was an independent prognostic factor for disease‐specific survival (HR 1.925, CI 1.21–3.04, p = 0.005). Increased presence of the pan T‐cell marker, CD3, which is an independent factor, correlates with improved clinical outcome in NSCLC. This prognostic impact of T cells is clearer in the tumor stroma. Neither plasma cells nor mast cells were prognostic indicators in our cohort.  相似文献   
8.
Human beta-defensin 2 (DEFB4, also known as DEFB2 or hBD-2) is a salt-sensitive antimicrobial protein that is expressed in lung epithelia. Previous work has shown that it is encoded in a cluster of beta-defensin genes at 8p23.1, which varies in copy number between 2 and 12 in different individuals. We determined the copy number of this locus in 355 patients with cystic fibrosis (CF), and tested for correlation between beta-defensin cluster genomic copy number and lung disease associated with CF. No significant association was found.  相似文献   
9.
The inactive X (Xi) differs from its active homologue (Xa) in a number of ways, including increased methylation of CpG islands, replication late in S phase, underacetylation of histone H4 and association with XIST RNA. Global changes in DNA methylation occur relatively late in development, but the other properties all change during or shortly after the establishment of Xi and may play a role in the mechanism by which an inactive chromatin conformation spreads across most of the chromosome. In the present report, we use two human X;autosome translocation chromosomes to study the spreading of inactive X chromatin across X;autosome boundaries. In one of these chromosomes, t(X;6), Xp distal to p11.2 is replaced by 6p21.1-6pter and, in the other, ins(X;16), a small fragment derived from 16p13 is inserted into the distal third of Xq. In lymphoid cells from patients carrying these translocations in an unbalanced form, Xi was shown by HUMARA assay to be derived exclusively [t(X:6)] or predominantly [ins (X;16)] from the derived X chromosome. We used a combination of immunolabelling and RNA/DNA fluorescence in situ hybridization to define the distribution of XIST RNA, deacetylated H4 and late-replicating DNA across the two derived X chromosomes in inactive form. Within the limits of the cytogenetic techniques employed, the results show complete coincidence of these three parameters, with all three being excluded from the autosomal component of the derived X chromosome.   相似文献   
10.
We have recently shown using dansyl-L-lysine exclusion studies that the release of human chorionic gonadotrophin (HCG) in conjunction with L- lactate dehydrogenase (LDH) from first trimester villi during organ culture is symptomatic of syncytiotrophoblast degeneration. The purpose of this study was to examine chorionic villi at the ultrastructural level in order to determine events occurring during organ culture. The tissue was sampled after 0, 24, 48 and 120 h in culture and processed for electron microscopy. In addition to confirming the previously recorded syncytial degeneration, the electron micrographs showed clearly the generation of a new syncytiotrophoblast layer. The new layer, derived from differentiating cytotrophoblast cells, was largely formed by 48 h and was maintained for at least 120 h in culture. This study demonstrates a model which provides an opportunity to study the differentiation of cytotrophoblast cells whilst they retain their anatomical relationships within the villous structure.   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

京公网安备 11010802026262号