全文获取类型
收费全文 | 693篇 |
免费 | 42篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 21篇 |
妇产科学 | 46篇 |
基础医学 | 56篇 |
口腔科学 | 8篇 |
临床医学 | 55篇 |
内科学 | 122篇 |
皮肤病学 | 7篇 |
神经病学 | 37篇 |
特种医学 | 13篇 |
外科学 | 174篇 |
综合类 | 18篇 |
现状与发展 | 1篇 |
一般理论 | 1篇 |
预防医学 | 47篇 |
眼科学 | 39篇 |
药学 | 41篇 |
中国医学 | 2篇 |
肿瘤学 | 41篇 |
出版年
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 27篇 |
2020年 | 7篇 |
2019年 | 16篇 |
2018年 | 28篇 |
2017年 | 21篇 |
2016年 | 16篇 |
2015年 | 26篇 |
2014年 | 22篇 |
2013年 | 33篇 |
2012年 | 70篇 |
2011年 | 53篇 |
2010年 | 37篇 |
2009年 | 23篇 |
2008年 | 43篇 |
2007年 | 40篇 |
2006年 | 36篇 |
2005年 | 32篇 |
2004年 | 33篇 |
2003年 | 29篇 |
2002年 | 25篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 10篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 10篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有738条查询结果,搜索用时 0 毫秒
731.
Diagnostic yield of CT pulmonary angiography for pulmonary embolism in clinically suspected patients
Pulmonary embolism (PE) is a common medical problem. Its diagnostic criteria must be reviewed to determine the need for confirmatory testing. Computed tomography pulmonary angiography (CTPA) is the current standard of care, which provides accurate diagnosis with rapid turnaround. This study aimed to estimate the diagnostic yield of CTPA in clinically suspected PE patients in a tertiary care hospital in Saudi Arabia.Radiology records of all patients with clinically suspected PE who underwent CTPA between January 1, 2012 and September 30, 2018 were reviewed retrospectively. A radiologist with 10 years of professional experience interpreted and reported all cases. The Wells score with 2 tiers (likely and unlikely) was used to raise the clinical suspicion of PE.Positive results for PE were reported in 177 out of 534 clinically suspected cases (33%). Among the positive PE cases, 143 were acute (81%) and 34 (19%) were chronic. Bilateral, right-sided, and left-sided PE were found in 115 (65%), 37 (21%), and 25 (14%) cases, respectively. Involvement of the segmental branches, subsegmental branches, and the pulmonary trunk were noted in 152 (86%), 70 (40%), and 9 cases (5%), respectively. Saddle PE was found in (4%) of the cases. The lower lobe branches (right 55%, left 53%) and the upper lobe branches (right 47%, left 41%) were the most common sites of involvement.CTPA had a higher positive detection rate for PE among clinically suspected cases than its published diagnostic yield. Adequate clinical evaluation when selecting patients for CTPA is emphasized to minimize unjustified exposure of the patients to radiation and intravenous contrast administration. It is crucial for radiologists to provide detailed reports commenting on all relevant findings, including pertinent negatives. A template for reporting radiological findings for CTPA can be recommended for this purpose. 相似文献
732.
INTRODUCTION AND AIMS: Calcium and vitamin D play major roles in calcium homeostasis and skeletal development, especially during pregnancy. This study was conducted to determine changes in calcium, 25 hydroxy [25(OH)] vitamin D3 and other biochemical factors (PTH, osteocalcin, alkaline phosphatase, magnesium, phosphorus) related to calcium homeostasis and bone turnover during pregnancy and compare the values to those of non-pregnant women. MATERIALS AND METHODS: In a cohort study, 48 pregnant women, in their first trimester of pregnancy (12+/-2.7 weeks), from 5 prenatal care centers, and 47 non-pregnant women randomly selected from the Tehran Lipid and Glucose Study (TLGS) population were enrolled. These pregnant women were followed in their second (26+/-1.9 weeks) and third trimesters (37+/-3.2 weeks) of pregnancy. Samples were drawn from June 2002 to March 2003. Including criteria were healthy women with no background of disease. Women using photo protection and calcium and vitamin D supplementation were excluded. A questionnaire was used to obtain demographic information for both groups. Venous blood samples were taken after 12-14 h of overnight fasting to measure serum calcium, phosphorus, magnesium, alkaline phosphatase, PTH, 25 (OH) vitamin D3 and serum osteocalcin levels. The repeated measures analysis of variance and t-test were used for statistical analysis. Data were matched for age and weight in both the case (in the first trimester) and control groups. RESULTS: Significant differences were found in the mean serum levels of osteocalcin and alkaline phosphatase between the three trimesters of pregnancy (p< 0.001). Osteocalcin was significantly higher in the first trimester as compared to second and third trimesters of pregnancy. Alkaline phosphatase was significantly lower in the first trimester as compared to the second and third trimesters of pregnancy and their controls. There was also a significant difference in osteocalcin in the second and third trimesters and alkaline phosphatase in the first and third trimesters of pregnancy in comparison to the control group. The mean values of osteocalcin were 12.7+/-8.5, 8.1+/-6.9, 5.6+/-5.0 and 13.9+/-7.9 ng/ml, respectively, and mean values for alkaline phosphatase were 115+/-38, 125+/-37, 174+/-61 and 134+/-35.0 Iu/l, respectively. In the first trimester, alkaline phosphatase was lower and osteocalcin was higher than in the second and third trimesters. In the first trimester of pregnancy, 20 and 40% of women had 25(OH) vitamin D3 < 10 and < 20 ng/ml, respectively, and 19% of women had serum calcium levels < 8.6 mg/dl. CONCLUSION: 60% of women in the first trimester, 48% in the second and 47% in the third trimester had either severe or moderate vitamin D deficiency. It is recommended that the importance of calcium supplements with vitamin D in pregnant women be stressed for these individuals. 相似文献
733.
Ghazi M Mounach A Nouijai A Ghozlani I Bennani L Achemlal L Bezza A El Maghraoui A 《Clinical rheumatology》2007,26(12):2037-2041
Measuring bone mineral density (BMD) is a widely accepted strategy for identifying subjects with an increased risk of fracture.
However, because of limited availability of BMD technology in some communities and cost considerations, it has been proposed
that BMD measurements be targeted to subjects with risk factors for osteoporosis. Osteoporosis self-assessment tool (OST)
using age and weight have been developed to identify women who are more likely to have low BMD and thus undergo BMD testing.
To study the performance of OST in identifying osteoporotic white men in Morocco. We analysed in an epidemiological cross-sectional
study the records for 229 white Moroccan men seen at an out-patient rheumatology centre. OST was compared to bone density
T scores and the ability of OST to identify men with osteoporosis (T < −2.5) was evaluated. Using an OST score < 2 to recommend dual X-ray absorptiometry (DXA) referral, sensitivity ranged from
63% at the lumbar spine to 87% at the total hip to detect BMD T scores of −2.5 and specificity from 58 to 59%. The negative
predictive value was high at all skeletal sites (87–98%), demonstrating the usefulness of the OST to identify patients who
have normal BMD and should not receive DXA testing. The performance of OST among men in Morocco was similar to that reported
earlier for the other samples in Asian countries and the USA. The OST is an effective and efficient tool to help target high-risk
men for DXA measurement. 相似文献
734.
735.
Scott Krauss Sydney Paul Pryor Garnet Raven Angela Danner Ghazi Kayali Richard J. Webby Robert G. Webster 《Influenza and other respiratory viruses》2013,7(1):93-96
Please cite this paper as: Krauss et al. (2012) Respiratory tract versus cloacal sampling of migratory ducks for influenza A viruses: are both ends relevant? Influenza and Other Respiratory Viruses DOI: .
Background Early studies in dabbling ducks showed that cloacal swabs yielded a larger number of avian influenza virus (AIV) isolates than did respiratory tract swabs. Historically, AIV surveillance has been performed by collecting cloacal or environmental fecal samples only. Highly pathogenic avian influenza H5N1 virus emerged in 1996 and replicated to higher titers in the respiratory rather than the gastrointestinal tract of ducks, prompting the collection of respiratory samples in addition to cloacal swabs from wild birds. Studies confirmed that some virus subtypes, especially H9 and highly pathogenic H5, are shed primarily through the respiratory tract and may not be detected in cloacal swabs.
Objectives To examine prevalence and subtype differences for AIV isolates from cloacal or respiratory swabs of wild ducks and to determine whether individual respiratory tract samples should be included in AIV surveillance studies in wild birds.
Methods Individual respiratory tract and cloacal swabs were collected from each of 1036 wild ducks in Alberta, Canada, during the month of August from 2007 to 2010 in an ongoing surveillance study. Virus isolation in eggs and subtype identification by antigenic and molecular methods were performed.
Results and conclusions Respiratory tract and cloacal swabs yielded ten influenza virus HA subtypes representing 28 HA–NA combinations. Three HA–NA subtype combinations were found exclusively in respiratory tract samples. Only four HA subtypes (H1, H3, H4, and H7) were recovered from respiratory samples, but respiratory shedding was associated with the dominance of 1 year’s subtype. Might respiratory shedding provide a risk assessment indicator? 相似文献
736.
737.
738.