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   619篇
  免费   36篇
  国内免费   4篇
耳鼻咽喉   4篇
儿科学   39篇
妇产科学   6篇
基础医学   62篇
口腔科学   11篇
临床医学   48篇
内科学   113篇
皮肤病学   9篇
神经病学   18篇
特种医学   94篇
外科学   61篇
综合类   61篇
预防医学   31篇
眼科学   18篇
药学   27篇
肿瘤学   57篇
  2022年   10篇
  2021年   9篇
  2020年   7篇
  2019年   4篇
  2018年   12篇
  2017年   8篇
  2016年   7篇
  2015年   20篇
  2014年   8篇
  2013年   13篇
  2012年   21篇
  2011年   21篇
  2010年   28篇
  2009年   22篇
  2008年   20篇
  2007年   20篇
  2006年   22篇
  2005年   29篇
  2004年   9篇
  2003年   15篇
  2002年   18篇
  2001年   12篇
  2000年   10篇
  1999年   13篇
  1998年   29篇
  1997年   24篇
  1996年   19篇
  1995年   15篇
  1994年   14篇
  1993年   9篇
  1992年   5篇
  1991年   6篇
  1989年   19篇
  1988年   16篇
  1987年   17篇
  1986年   13篇
  1985年   7篇
  1984年   10篇
  1983年   7篇
  1982年   7篇
  1981年   6篇
  1980年   8篇
  1976年   4篇
  1975年   11篇
  1972年   3篇
  1971年   3篇
  1969年   4篇
  1968年   4篇
  1967年   3篇
  1932年   3篇
排序方式: 共有659条查询结果,搜索用时 15 毫秒
31.
We describe an unusual infant with the diagnosis of alveolar capillary dysplasia who had a relatively prolonged life without extracorporeal membrane oxygenation (ECMO). We have used this case as a springboard for a thorough review of the literature. This was a full-term female infant who presented with a picture of persistent pulmonary hypertension of the newborn. She was treated as such, with various ventilatory modes, alkalinizing agents, surfactant therapy, tolazoline, prostacyclin and nitric oxide. Because of the prolonged clinical course the possibility of alveolar capillary dysplasia was raised. The parents refused ECMO. Despite all efforts she progressively deteriorated and died at 22 days of age. Macro- and microscopic examination of the lung at autopsy were diagnostic of alveolar capillary dysplasia. A detailed review of 39 cases published in the literature with comments regarding incidence, etiology, pathophysiology, clinical picture, diagnosis and treatment is presented.  相似文献   
32.
Objectives : To determine the efficacy of antimicrobial treatment in non-dysenteric persistent diarrhoea in a community setting. Methods : In this double-blind field trial, 156 children aged 4 36 months with persistent diarrhoea not associated with Giardia lamblia infestation seeking treatment in a community outpatient clinic, were randomized to receive a combination of nalidixic acid and metronidazole, metronidazole alone, or placebo for 7 days. Results : In comparison with placebo, metronidazole treatment did not result in a significant reduction in the mean post-enrolment diarrhoeal duration and stool frequency, increase in the proportion of patients recovered by days 3, 5 and 7 of treatment, and increase in weight gain at days 7 and 14. Comparing the combination of nalidixic acid and metronidazole with metronidazole alone, 17.5% more children treated with the combination recovered by day 3 of treatment ( p = 0.08) and the mean stool frequency ascertained on day 7 for the previous 24 h was 26.8% less in them ( p = 0.05). The weight gains at days 7 and 14 were similar in the two groups. Conclusions : These findings indicate that metronidazole offers no therapeutic benefit in persistent diarrhoea not associated with Giardia lamblia and nalidixic acid has only a modest clinical benefit, which is not substantial enough to warrant its routine use.  相似文献   
33.

Background

Haemorrhage after Cardio Pulmonary Bypass (CPB) Surgery is a well recognised complication that leads to significant morbidity and mortality. The incidence varies between 5-25% depending upon the clinical situation. Several factors are implicated as causative but none have been precisely proved.

Methods

Our study was an attempt to evaluate the haemostatic defect with particular reference to platelet function abnormalities during cardio pulmonary bypass surgery, in order to reduce the morbidity and mortality associated with post CPB haemorrhage. Flow cytometric evaluation of different platelet glycoproteins like GPIb/IX, GPIIb/IIIa and GMP-140 was done.

Results

The marker expression showed deregulation during surgery which returned to base after bypass was terminated. In contrast, the cases with bleeding showed significant variation. P-Selectin (GMP 140) expression decreased progressively till 3rd post-operative day showing lack of activation of platelets in cases of severe bleeding.

Conclusion

Longer duration of CPB initiates plasmin generation through heparin, which raises the PAI-1-tPA complex and thereby down regulating the functions of platelets. This suggests a link between duration of CPB, bleeding, platelet dysfunction and fibrinolysis. Hence serial estimations of the levels of GMP-140 and tPA can predict severe bleeding.Key Words: CardioPulmonary Bypass, Platelet dysfunction, flowcytometry, platelet glycoproteins, haemorrhage  相似文献   
34.
The natural variability on a spatial and temporal scale was examined in the zooplankton community of mesocosms from Syngenta Crop Protection AG (Stein, Switzerland), with the focus on improving the experimental design and evaluation of mesocosm studies. Analysis was performed using zooplankton data collected during a three-year period in 3 (1996 and 1998) to 12 (1997) ponds. Interreplicate variability was measured as the variance among the 3 to 12 replicates at each sampling date. Temporal variation was examined as seasonal variability by comparing different sampling dates within a year and as year-to-year variation by comparing pooled data year by year. Univariate and multivariate methods were used for the evaluation of population and community data, respectively. Results from the present study indicate that because of the low interreplicate variability, only data from high-abundance species could be evaluated with a precision able to detect effects less than 20%. For the majority of the zooplankton populations, abundances were lower than 10 organisms/L, with frequent zero counts resulting in a weak evaluation of the data with a precision able to detect effects of greater than 20 and 110%. Ordination analysis of the community data from the three years revealed that approximately 29% of the total variance could be explained by year-to-year differences, whereas 11% could be attributed to seasonal variability within a year. The residual variance can be attributed to interreplicate variability and sampling error. These results were in line with findings for individual populations. The present analysis demonstrated that the inherent variability of a system should be investigated for a proper design and evaluation of mesocosm studies and promotes the use of multivariate tools for a more comprehensive interpretation of mesocosm data.  相似文献   
35.
The shape of a patient's face is commonly used as a reference to select the shape of the maxillary central incisors in edentulous patients. The validity of this relationship has not been proved. The objective of this clinical study was to determine whether a relationship exists between maxillary central incisors and face shapes. Casts were made of the maxillas of 50 men and 50 women. A standardized digital photographic procedure was used to record frontal views of each subject's face and of the maxillary central incisors of the dental casts. The shapes of the maxillary central incisors were compared with the face forms. Shape matches were evaluated according to their Hausdorff distance (HDD). The function h(A,B) is called the directed HDD from shape A to shape B (this function is not a true distance). It reflects the distance of the point of shape A that is farthest from any point of shape B and vice versa. The similarity of both shapes is given as a non-negative number. The value 0.0 indicates that the figures are identical (after scaling and shifting). Higher values indicate that shapes differ more substantially. Significant differences on the 5% level were calculated using the non-parametric Mann-Whitney U and Kruskal-Wallis tests. The face shape from the chin margin to the eyebrow line (superior edges of the eyebrows) produced a better match than the one from the chin to the hairline (P < 0.0001). On average, the maxillary central incisors displayed a variability (0.084 +/- 0.028) that was higher by a factor of 1.9 than the face shapes (chin margin to the eyebrow line, 0.045 +/- 0.015). In the interindividual comparison, the shapes of the maxillary central incisors of women displayed a significantly smaller HDD than the ones of the men (P < 0.0001).  相似文献   
36.
Substance abuse is a widely identified problem in our society. Alcohol abuse is the most problematic, yet most undertreated. Primary care practitioners often do not screen the geriatric population appropriately for at-risk drinking, so the condition goes undiagnosed. This oversight is complicated by the fact that many manifestations of alcohol abuse do not present themselves until well into the disease process. This article explores the practitioner's role in geriatric alcohol abuse assessment and treatment and the impact of geriatric alcohol abuse on society.  相似文献   
37.
38.
Iliopsoas impingement is a commonly recognised source of groin pain following total hip replacement. When conservative measures fail, open or arthroscopic iliopsoas tendon release can reliably alleviate pain and improve function. This article describes an alternative ultrasound‐guided percutaneous technique, achieving iliopsoas tenotomy utilising a modified 18G coaxial needle and thus minimising the morbidity and cost associated with an open or arthroscopic procedure. This method proved successful with resultant complete resolution of patient symptoms. To the knowledge of the authors, this is the first case of ultrasound‐guided percutaneous iliopsoas tenotomy for iliopsoas impingement post total hip replacement.  相似文献   
39.
40.
Mutations in the PEX gene at Xp22.1 (phosphate-regulating gene with homologies to endopeptidases, on the X-chromosome), are responsible for X-linked hypophosphataemic rickets (HYP). Homology of PEX to the M13 family of Zn2+ metallopeptidases which include neprilysin (NEP) as prototype, has raised important questions regarding PEX function at the molecular level. The aim of this study was to analyse 99 HYP families for PEX gene mutations, and to correlate predicted changes in the protein structure with Zn2+ metallopeptidase gene function. Primers flanking 22 characterised exons were used to amplify DNA by PCR, and SSCP was then used to screen for mutations. Deletions, insertions, nonsense mutations, stop codons and splice mutations occurred in 83% of families screened for in all 22 exons, and 51% of a separate set of families screened in 17 PEX gene exons. Missense mutations in four regions of the gene were informative regarding function, with one mutation in the Zn2+-binding site predicted to alter substrate enzyme interaction and catalysis. Computer analysis of the remaining mutations predicted changes in secondary structure, N-glycosylation, protein phosphorylation and catalytic site molecular structure. The wide range of mutations that align with regions required for protease activity in NEP suggests that PEX also functions as a protease, and may act by processing factor(s) involved in bone mineral metabolism.   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