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   479篇
  免费   38篇
  国内免费   13篇
耳鼻咽喉   5篇
儿科学   49篇
妇产科学   1篇
基础医学   139篇
口腔科学   1篇
临床医学   31篇
内科学   167篇
皮肤病学   6篇
神经病学   29篇
特种医学   4篇
外科学   45篇
综合类   21篇
预防医学   11篇
眼科学   10篇
药学   3篇
肿瘤学   8篇
  2022年   2篇
  2021年   9篇
  2020年   3篇
  2018年   8篇
  2017年   8篇
  2016年   13篇
  2015年   4篇
  2014年   12篇
  2013年   6篇
  2012年   35篇
  2011年   37篇
  2010年   10篇
  2009年   13篇
  2008年   29篇
  2007年   40篇
  2006年   37篇
  2005年   42篇
  2004年   42篇
  2003年   48篇
  2002年   44篇
  2001年   31篇
  2000年   4篇
  1999年   7篇
  1998年   8篇
  1997年   8篇
  1996年   4篇
  1995年   4篇
  1994年   4篇
  1993年   1篇
  1992年   2篇
  1990年   6篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1984年   2篇
  1952年   1篇
排序方式: 共有530条查询结果,搜索用时 332 毫秒
1.
Background: Volatile anesthetics are commonly used for general anesthesia. However, these can induce profound cardiovascular alterations. Xenon is a noble gas with potent anesthetic and analgesic properties. However, it is uncertain whether xenon alters myocardial function. The aim of this study was therefore to investigate left ventricular function during anesthesia with xenon compared with isoflurane.

Methods: The authors performed a randomized multicenter trial to compare xenon with isoflurane with respect to cardiovascular stability and adverse effects in patients without cardiac diseases scheduled for elective surgery. Two hundred fifty-nine patients were enrolled in this trial, of which 252 completed the study according to the protocol. Patients were anesthetized with xenon or isoflurane, respectively. Before administration of the study drugs and at four time points, the effects of both anesthetics on left ventricular function were investigated using transesophageal echocardiography.

Results: Global hemodynamic parameters were significantly altered using isoflurane (P < 0.05 vs. baseline), whereas xenon only decreased heart rate (P < 0.05 vs. baseline). In contrast to xenon, left ventricular end-systolic wall stress decreased significantly in the isoflurane group (P < 0.05 vs. baseline). Velocity of circumferential fiber shortening was decreased significantly in the xenon group but showed a more pronounced reduction during isoflurane administration (P < 0.05 vs. baseline). The contractile index (difference between expected and actually measured velocity of circumferential fiber shortening) as an independent parameter for left ventricular function was significantly decreased after isoflurane (P < 0.0001) but unchanged using xenon.  相似文献   

2.
This open multicenter study was performed in 20 hospital gynecological units in the UK. The effects of 600 mg oral mifepristone as pretreatment to vaginal prostaglandin induction of second second trimester abortion was studied in 267 women.

The primary efficacy variable was the abortion induction interval, defined as the time taken to expel the fetus from the time of administration of the first prostaglandin pessary. Induction was commenced 36 to 48 hours following mifepristone intake.

The mean abortion induction interval was 7 h. A total of 81.9% of women aborted within 12 h. There was a significant relationship between abortion induction interval and age of gestation, and a significant inverse relationship between abortion induction interval and parity.

Vomiting, pelvic pain, and nausea were the most frequently reported adverse events. Two patients required transfusion and one patient with a uterine scar from a previous cesarean section suffered a ruptured uterus and hysterotomy.  相似文献   

3.
BACKGROUND: Bronchial responsiveness (BR) to histamine or methacholin is a common finding in adult non-asthmatic patients with allergic rhinitis. OBJECTIVE: We tested whether BR is also present in children with a comparatively short history of allergic rhinitis in a paediatric cohort. METHODS: We performed pulmonary function tests and histamine challenges in a total of 654 children (age 7 years, participants of the German Multicenter Allergy Study) and compared PC20 FEV1 values in children with asthma, allergic rhinitis, asymptomatic allergic sensitization and non-atopic controls. RESULTS: Most pronounced BR to histamine was observed in allergic asthmatics (n = 28), irrespective of the presence or absence of allergic rhinitis. Furthermore, PC(20)FEV(1) values in non-asthmatic children with allergic rhinitis (n = 24) were not significantly different from those seen in asymptomatic atopic (n = 54) or non-atopic controls (n = 92). CONCLUSIONS: In contrast to adult study populations, 7-year-old non-asthmatic children with allergic rhinitis do not show a higher degree of BR than asymptomatic atopic or non-atopic controls. Therefore, secondary preventive measures in non-asthmatic children with allergic rhinitis (such as regular local anti-inflammatory therapy or specific immunotherapy) should be studied and applied more intensely to prevent bronchial hyper-responsiveness (BHR) and asthma in this high-risk group.  相似文献   
4.
转化生长因子-β在哮喘气道炎症与重塑中的作用   总被引:4,自引:0,他引:4       下载免费PDF全文
Transforming growth factor-β(TGF-β) was reported to be increased in asthma in some studies. Accumulation of TGF-β in airway promotes smooth muscle cell mitogenesis and hyperplasia, and in-duces fibroblast and myofibroblast and smooth muscle proliferation as well as increase in protein synthesis in connective tissue(such as collagen deposition on the reticular basement membrane). The autocrine induction of collagen expression by smooth muscle may contribute to the thickening of the reticular basement membrane, irre-versible f‘throsis and remodeling seen in the airways in some asthmatics. TGF-β is considered to be a major fi-brogenic cytokine. It can increase smooth muscle mass and lead to severe bronchial obstruction in an asthma at-tack.  相似文献   
5.
The quality parameters for the detection of microsporidia in identical sets of 50 stool samples were determined for six laboratories where technicians used light microscopy and for six laboratories where technicians used PCR. The average overall sensitivities were 67% (89% for patient samples only) for the PCR laboratories and 54% (80% for patient samples only) for the light microscopy laboratories. Specificities were 98 and 95%, respectively. Differences in results were most apparent between the individual laboratories rather than between the two major methods used.  相似文献   
6.
7.
Phenotypes and genetic relatedness of invasive Haemophilus influenzae strains were evaluated from 1989 through 2001. Among 119 isolates, multidrug resistance decreased (from 50 to 0%), the level of H. influenzae serotype b (Hib) strains declined (from 81 to 16%), the level of noncapsulated strains rose (from 19 to 80%), and the first invasive H. influenzae serotype f strain was described. This study documents changes in invasive H. influenzae infections in Portugal, i.e., the emergence of non-type-b strains that are genetically diverse and unrelated to Hib.  相似文献   
8.
Within the GEN-COVID Multicenter Study, biospecimens from more than 1000 SARS-CoV-2 positive individuals have thus far been collected in the GEN-COVID Biobank (GCB). Sample types include whole blood, plasma, serum, leukocytes, and DNA. The GCB links samples to detailed clinical data available in the GEN-COVID Patient Registry (GCPR). It includes hospitalized patients (74.25%), broken down into intubated, treated by CPAP-biPAP, treated with O2 supplementation, and without respiratory support (9.5%, 18.4%, 31.55% and 14.8, respectively); and non-hospitalized subjects (25.75%), either pauci- or asymptomatic. More than 150 clinical patient-level data fields have been collected and binarized for further statistics according to the organs/systems primarily affected by COVID-19: heart, liver, pancreas, kidney, chemosensors, innate or adaptive immunity, and clotting system. Hierarchical clustering analysis identified five main clinical categories: (1) severe multisystemic failure with either thromboembolic or pancreatic variant; (2) cytokine storm type, either severe with liver involvement or moderate; (3) moderate heart type, either with or without liver damage; (4) moderate multisystemic involvement, either with or without liver damage; (5) mild, either with or without hyposmia. GCB and GCPR are further linked to the GCGDR, which includes data from whole-exome sequencing and high-density SNP genotyping. The data are available for sharing through the Network for Italian Genomes, found within the COVID-19 dedicated section. The study objective is to systematize this comprehensive data collection and begin identifying multi-organ involvement in COVID-19, defining genetic parameters for infection susceptibility within the population, and mapping genetically COVID-19 severity and clinical complexity among patients.Subject terms: Genetics research, Viral infection  相似文献   
9.
BACKGROUND: Eosinophilic airways inflammation forms the pathophysiologic basis for a proportion of children at risk of developing recurrent wheezing. Early preventive measures and/or anti-inflammatory treatment may be guided by the identification of such children. We aimed to study the relationship between respiratory symptoms and indirect markers of airway inflammation. METHODS: We measured eosinophil protein X (EPX) and leukotriene E(4) (LTE(4)) in urine, as well as eosinophil cationic protein (ECP) in nasal lavages, in a random sample of 1-year-old children with a family history of atopy who participated in an international multicenter study on the prevention of allergy in Europe. For urine analyses, 10 children with upper respiratory illness and 19 healthy children without a family history of atopy were also enrolled. Endogenous urinary LTE(4) was separated by HPLC and determined by enzyme immunoassay with a specific antibody. The concentrations of nasal ECP and urinary EPX were determined by RIA analysis. RESULTS: One hundred and ten children (mean age: 1.05+/-0.1 years) were enrolled. Prolonged coughing during the first year of life was reported in 29 children, wheezy breathing in 17 children, and dry skin in 33 children. A doctor's diagnosis of wheezy bronchitis was given to 17 children. Sensitization to dust mites (specific IgE > or =1.43 ML/units) was detected in two children. Children with a doctor's diagnosis of atopic dermatitis within the first 12 months of life (n=6) had significantly higher urinary EPX than children without this (66.7 vs 30.1 microg/mmol creatinine, P=0.01). Urinary excretion of EPX and LTE4 showed a weak correlation (r=0.22, P=0.02). There were no significant differences in urinary excretion of EPX and LTE(4) or nasal ECP between children with and without respiratory symptoms (P>0.1). CONCLUSIONS: At the age of 1 year, urinary EPX is increased in children with atopic dermatitis. With regard to respiratory symptoms, urinary and nasal inflammatory parameters are not helpful in characterizing the phenotype of a single patient.  相似文献   
10.
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