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   364篇
  免费   23篇
  国内免费   2篇
耳鼻咽喉   2篇
儿科学   10篇
妇产科学   6篇
基础医学   40篇
口腔科学   11篇
临床医学   14篇
内科学   66篇
皮肤病学   5篇
神经病学   37篇
特种医学   2篇
外科学   30篇
综合类   3篇
预防医学   22篇
眼科学   104篇
药学   13篇
中国医学   4篇
肿瘤学   20篇
  2024年   1篇
  2023年   3篇
  2022年   2篇
  2021年   7篇
  2020年   8篇
  2019年   10篇
  2018年   8篇
  2017年   3篇
  2016年   11篇
  2015年   10篇
  2014年   9篇
  2013年   20篇
  2012年   27篇
  2011年   29篇
  2010年   21篇
  2009年   16篇
  2008年   29篇
  2007年   22篇
  2006年   23篇
  2005年   13篇
  2004年   19篇
  2003年   10篇
  2002年   11篇
  2001年   10篇
  2000年   10篇
  1999年   5篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1992年   6篇
  1991年   3篇
  1990年   3篇
  1989年   4篇
  1988年   4篇
  1987年   7篇
  1986年   3篇
  1985年   2篇
  1980年   3篇
  1978年   2篇
  1977年   1篇
  1975年   1篇
  1969年   1篇
  1968年   2篇
  1967年   1篇
  1966年   2篇
  1964年   2篇
排序方式: 共有389条查询结果,搜索用时 46 毫秒
1.
To obtain a new model of chronic portal hypertension in the rat, two classical methods to produce portal hypertension, partial portal vein ligation and the oral administration of thioacetamide (TAA), have been combined. Male Wistar rats were divided into four groups: 1 (control; n?=?10), 2 [triple partial portal vein ligation (TPVL); n?=?9], 3 (TAA; n?=?11), and 4 (TPVL plus TAA; n?=?9). After 3 months, portal pressure, types of portosystemic collateral circulation, laboratory hepatic function tests (aspartate aminotransferase, alanine aminotransferase, bilirubin, alkaline phosphatase, and gamma-glutamyl transpeptidase) and liver histology were studied. The animals belonging to group 2 (TPVL) developed extrahepatic portosystemic collateral circulation, associated with mesenteric venous vasculopathy without hepatic destructurization or portal hypertension. Animals from group 3 (TAA) developed cirrhosis and portal hypertension but not extrahepatic portosystemic collateral circulation, or mesenteric venous vasculopathy. Finally, the animals from group 4 (TPVL?+?TAA) developed cirrhosis, portal hypertension, portosystemic collateral circulation, and mesenteric venous vasculopathy. The association of TPVL and TAA can be used to obtain a model of chronic portal hypertension in the rat that includes all the alterations that patients with hepatic cirrhosis usually have. This could, therefore, prove to be a useful tool to study the pathophysiological mechanisms involved in these alterations.  相似文献   
2.
This study attempted to define the possible contribution of zinc nutrition to immunocompetence and growth in severely malnourished infants. The effect of zinc supplementation was evaluated in marasmic infants during nutritional rehabilitation by using a controlled double-blind design in which 19 infants fed a zinc-fortified formula were compared with 20 infants fed the same non-supplemented formula. Evaluation of immunocompetence, growth, and zinc, copper, and iron status was performed on admission and at 30, 60, and 105 d of nutritional rehabilitation. Although energy intake was similar in both groups, the zinc-supplemented infants had significantly higher linear growth gain, and their immune function improved as demonstrated by conversion of their delayed hypersensitivity skin reactions, enhanced lymphoproliferative response to PHA, and increased salivary IgA concentrations. Thus, the use of a zinc-fortified formula during nutritional rehabilitation can prevent the development of zinc deficiency and improve growth and immune function.  相似文献   
3.
PCR-restriction fragment length polymorphism analysis of heat shock protein 70 genes discriminates most neotropical Leishmania species, as well as Trypanosoma cruzi. The assay, combined with capillary electrophoresis in a microchip device, may be applied directly on clinical samples with a high sensitivity, hence supporting clinical and epidemiological monitoring of leishmaniasis.  相似文献   
4.
PURPOSE: To describe three Hispanic patients with oculodermal melanocytosis and uveal melanoma. METHOD: Case series. RESULTS: Three Hispanic patients with oculodermal melanocytosis and uveal melanoma underwent enucleation. The diagnosis of choroidal melanoma was confirmed by histopathologic examination. CONCLUSION: In the Hispanic population, uveal melanoma can occur in the presence of oculodermal melanocytosis.  相似文献   
5.
6.
7.
Post-translational modifications play a key role in tau protein aggregation and related neurodegeneration. Because hyperphosphorylation alone does not necessarily cause tau aggregation, other post-translational modifications have been recently explored. Tau acetylation promotes aggregation and inhibits tau’s ability to stabilize microtubules. Recent studies have shown co-localization of acetylated and phosphorylated tau in AD and some 4R tauopathies. We developed a novel monoclonal antibody against acetylated tau at lysine residue 274, which recognizes both 3R and 4R tau, and used immunohistochemistry and immunofluorescence to probe 22 cases, including AD and another eight familial or sporadic tauopathies. Acetylated tau was identified in all tauopathies except argyrophilic grain disease (AGD). AGD is an age-associated, common but atypical 4R tauopathy, not always associated with clinical progression. Pathologically, AGD is characterized by neuropil grains, pre-neurofibrillary tangles, and oligodendroglial coiled bodies, all recognized by phospho-tau antibodies. The lack of acetylated tau in these inclusions suggests that AGD represents a distinctive tauopathy. Our data converge with previous findings to raise the hypothesis that AGD could play a protective role against the spread of AD-related tau pathology. Tau acetylation as a key modification for the propagation tau toxicity deserves further investigation.  相似文献   
8.
Objective: The purpose of this study was to describe the fetal/neonatal cytomegalovirus (CMV) status according to chorionicity and outcome in twin pregnancies diagnosed with CMV.

Methods: An opportunistic diagnosis of CMV infection was performed in a tertiary referral center. All cases diagnosed in twin pregnancies (2006–2011) were included. Prenatal diagnosis was performed by CMV-DNA in the amniotic fluid (AF) of both fetuses only on the evidence of sonographic findings in either one or both twins. Neonatal screening was selectively assessed in symptomatic newborns, preterm, and infants born to HIV-infected mothers. Congenital infection was considered in the presence of CMV-DNA in AF, fetal tissues or newborn urine within the first 2 weeks of life, and symptomatic disease with clinical findings at birth or autopsy.

Results: A total of six twin pregnancies with congenital CMV infection were diagnosed, five dichorionic and one monochorionic diamniotic. Only one sibling was infected among dichorionic pregnancies, two diagnosed prenatally, and three after birth. In the monochorionic pregnancy, the diagnosis was performed prenatally and the two fetuses were infected and severely damaged.

Conclusions: Congenital CMV infection in twins might be related, among other factors, to chorionicity, and in DC twins a non-concordant infection can be expected.  相似文献   
9.
Introduction

While there is evidence of obstetric and neonatal outcomes from non-obstetric surgery during pregnancy, surgery during the third trimester of gestation has not been evaluated as a prognostic factor for those outcomes. The objective of this study was to determine whether appendectomies during the third trimester are associated with adverse neonatal outcomes, in comparison with appendectomies during the first two trimesters, based on national administrative data in Colombia.

Methods

A retrospective cohort study was performed using administrative health records. It included all women who had live births and who underwent an appendectomy during any stage of pregnancy, between the years 2011 and 2016, and who belonged to Colombia’s contributory health system. The main outcome was preterm birth. Birth weight and 1-min and 5-min Apgar scores were also measured, as well as outcomes used to identify neonatal near-miss cases. Propensity score matching was used in order to balance baseline characteristics (age, weeks of gestation, obstetric comorbidity index, and region and year the procedure was performed). Relative risks were estimated with Poisson regressions.

Results

This study included a total of 2507 women in Colombia’s contributory health system who underwent an appendectomy during pregnancy. Appendectomy was performed on 885 women (35.30%) in their first trimester, 1205 women (48.07%) in their second trimester, and 417 women (16.63%) in their third trimester. For the entire population, the preterm birth rate was 11.85 per 100 appendectomies. With the matched sample, this study found that women in their third trimester had a 1.65 greater risk of preterm birth [95% CI, 1.118–2.423], a 3.43 greater risk of birth at gestational ages < 33 weeks [95% CI, 1.363 to 8.625], 2.083 greater risk of weight under 1750 g [95% CI, 1.056–4.109], and a mean difference of − 0.247 [95% CI, − .382 to − .112] in the 1-min Apgar score and − .168a [95% CI, − .276 to − .060] in the 5-min Apgar. No differences were found in birth weight or Apgar scores < 7.

Conclusions

In Colombia’s contributory health system, women who undergo appendectomies in their third trimester have a greater risk of preterm birth, birth weight under 1750 g, birth at gestational ages less than 33 weeks, and decreased 1-min and 5-min Apgar scores.

  相似文献   
10.
Theiler’s murine encephalomyelitis virus (TMEV) induces demyelination in susceptible strains of mice (SJL/J) through an immunopathological process that is mediated by CD4+ Th1 T cell. These T cells are chemoattracted to the central nervous system by chemokines. Hence, in this study, we focused on the production of the chemokine “interferon-gamma-inducible protein 10 kDa,” or IP-10/CXCL10, by cultured SJL/J mouse astrocytes infected with the BeAn strain of TMEV and its capacity to attract activated T cells. The analysis of the whole murine genome by DNA hybridization with cRNAs from mock- and TMEV-infected cultures revealed the upregulation of six sequences that potentially encode for CXCL10. This increased CXCL10 expression was validated by PCR and qPCR. The presence of this chemokine was further demonstrated by enzyme-linked immunoassay (ELISA). Significantly, astrocytes from BALB/c mice, a strain resistant to demyelination, did not produce CXCL10. The secreted CXCL10 was biologically active, inducing chemoattraction of activated lymphocytes. The inflammatory cytokines, IL-1α, IFN-γ, and TNF-α, were strong inducers of CXCL10 in astrocytes. Serum from TMEV-infected SJL/J but not BALB/c mice contains CXCL10, the levels of which peak at the onset of the clinical disease. Finally, this in vitro inflammation model was fully inhibited by 17β-estradiol and four selective estrogen receptor modulators, as demonstrated by ELISA and qPCR.  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