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   28篇
  国内免费   20篇
儿科学   33篇
妇产科学   13篇
基础医学   71篇
口腔科学   8篇
临床医学   54篇
内科学   80篇
皮肤病学   13篇
神经病学   13篇
特种医学   111篇
外科学   36篇
综合类   10篇
预防医学   19篇
眼科学   9篇
药学   20篇
中国医学   2篇
肿瘤学   35篇
  2022年   2篇
  2021年   1篇
  2020年   5篇
  2019年   6篇
  2018年   11篇
  2017年   5篇
  2016年   7篇
  2015年   8篇
  2014年   10篇
  2013年   15篇
  2012年   10篇
  2011年   17篇
  2010年   18篇
  2009年   23篇
  2008年   16篇
  2007年   21篇
  2006年   15篇
  2005年   9篇
  2004年   6篇
  2003年   4篇
  2002年   6篇
  2001年   11篇
  2000年   3篇
  1999年   12篇
  1998年   31篇
  1997年   39篇
  1996年   28篇
  1995年   19篇
  1994年   17篇
  1993年   17篇
  1992年   2篇
  1991年   7篇
  1990年   13篇
  1989年   20篇
  1988年   12篇
  1987年   9篇
  1986年   8篇
  1985年   10篇
  1984年   4篇
  1983年   8篇
  1982年   6篇
  1981年   2篇
  1980年   11篇
  1979年   1篇
  1978年   1篇
  1977年   6篇
  1976年   7篇
  1975年   5篇
  1970年   1篇
  1968年   1篇
排序方式: 共有527条查询结果,搜索用时 46 毫秒
1.
The human visual system is amenable to a number of adaptive processes; one such process, or collection of processes, is the adaptation to blur. Blur adaptation can be observed as an improvement in vision under degraded conditions, and these changes occur relatively rapidly following exposure to blur. The potential important future directions of this research area and the clinical implications of blur adaptation are discussed.  相似文献   
2.
Objective: To assess the quality of images and video clips of fetal central nervous (CNS) structures obtained by ultrasound and transmitted via tele-ultrasound from Brazil to Australia.

Methods: In this cross-sectional study, 15 normal singleton pregnant women between 20 and 26 weeks were selected. Fetal CNS structures were obtained by images and video clips. The exams were transmitted in real-time using a broadband internet and an inexpensive video streaming device. Four blinded examiners evaluated the quality of the exams using the Likert scale. We calculated the mean, standard deviation, mean difference, and p values were obtained from paired t tests.

Results: The quality of the original video clips was slightly better than that observed by the transmitted video clips; mean difference considering all observers = 0.23 points. In 47/60 comparisons (78.3%; 95% CI?=?66.4–86.9%) the quality of the video clips were judged to be the same. In 182/240 still images (75.8%; 95% CI?=?70.0–80.8%) the scores of transmitted image were considered the same as the original.

Conclusion: We demonstrated that long distance tele-ultrasound transmission of fetal CNS structures using an inexpensive video streaming device provided images of subjective good quality.  相似文献   
3.
4.
OBJECTIVE AND DESIGN: To determine the expression pattern and distribution of the glucocorticoid-inducible protein annexin 1 (ANXA1) in a murine model of chronic granulomatous inflammation. MATERIALS OR SUBJECTS: TO Mouse. TREATMENT: Chronic granulomatous inflammation was induced by injecting into dorsal sub-cutaneous air-pouches in mice, a mixture of croton oil and Freund's complete adjuvant (CO/FCA). METHODS: Western and northern analysis, corticosterone assay, and immunohistochemistry. Statistical analysis was performed using ANOVA followed by Tukey's pair-wise comparisons or Dunnett's multiple comparisons. RESULTS: ANXA1 protein levels changed significantly throughout the 4-week time course, with an initial peak at day 7 and a later elevation at 28 days. ANXA1 mRNA levels peaked at days 1 and 3, with a significant decline at day 7 followed by an upward trend to day 28. Plasma corticosterone measurements taken throughout the time course revealed an increase from 14 days onward, suggesting that corticosterone does not influence ANXA1 expression during the initial stages of the model. Immunogold staining revealed that ANXA1 expression in the inflamed tissue was mainly in extravasated neutrophils, with intact protein (37 kDa) being predominantly observed on the cell membrane. CONCLUSIONS: The pattern of ANXA1 expression indicates that infiltrated neutrophils are responsible for the majority of ANXA1 present both at early and later stages of this model of granulomatous inflammation.  相似文献   
5.
6.
High serum fluoride (F-) in patients with chronic renal failure (CRF) and end-stage renal disease (ESRD) is associated with risk of renal osteodystrophy and other bone changes. This study was done to determine F- in normal healthy controls and patients with ESRD on haemodialysis (HD) or peritoneal dialysis (PD). Seventeen healthy controls (12 males, 5 females) and 39 ESRD patients on dialysis (17 males, 22 females) were recruited in the study in a community with 47.4 +/- 3.28 microM/l (range 44-51 microM/l) of F- content in drinking water. Control subjects showed a mean serum F- concentration of 1.08 +/- 0.350 microM/l. Males in control group showed slightly higher F- levels (1.15 +/- 0.334, range 0.55-1.9 microM/l) than females (0.92 +/- 0.370, range 0.6-1.5 microM/l). Mean serum F- concentration did not correlate significantly with age and sex among control subjects, whereas such correlation was observed in patients with ESRD on dialysis. Mean serum F- concentration was significantly higher in patients on dialysis (2.67 +/- 1.09, range 0.8-5.2 microM/l) than normal controls. When grouped according to sex, the mean serum F- concentration in males (3.05 +/- 1.04, range 1.8-5.2 microM/l) was significantly higher than females (2.38 +/- 1.08, range 0.8-5.2 microM/l). When patients were grouped according to age, it was observed that F- concentration was significantly higher in patients with age groups 21-70 (2.86 +/- 1.05) than those with age group 13-20 years (1.42 +/- 0.531). Thus F- concentration correlated with age and sex, being higher in males and above 20 years. Despite appreciable clearance of F- (39-90%) across the peritoneum, patients on CAPD showed higher serum F- concentration than those on HD (3.1 +/- 1.97 vs 2.5 +/- 1.137 microM/l). Of the total 39 patients on dialysis 39% had their serum F- concentration above 3.0 microM/l, posing the risk of renal osteodystrophy.   相似文献   
7.
8.
In a double blind randomized crossover trial lasting 6 months selegiline, a selective MAO-B inhibitor, was tested against placebo for activity on verbal memory performances in Alzheimer-type dementia (DAT). Verbal memory was assessed with the Rey-Auditory-Verbal Learning Test at the start of treatment, at the time scheduled for crossover (90 days) and at the end of the trial (180 days). The results suggest that selegiline possesses significant activity on some memory parameters, which seems to depend on an improvement both in information processing abilities and in learning strategies at the moment of acquisition
Sommario In uno studio doppio cieco cross-over, randomizzato verso placebo della durata di sei mesi, è stata analizzata l'influenza della selegilina, inibitore selettivo delle MAO-B, sulle prestazioni di memoria verbale di 22 pazienti con diagnosi clinica di demenza tipo Alzheimer (DAT). L'esame della memoria verbale è stato effettuato con il Rey-Auditory Verbal Learning test all'inizio del trattamento, dopo 90 giorni, momento previsto per il cross-over, e dopo 180 giorni, al termine della sperimentazione. I risultati suggeriscono una significativa efficacia della selegilina su alcuni parametri di memoria, che sembrano riconducibili ad un miglioramento sia delle capacità di elaborazione delle informazioni, sia delle strategie di apprendimento al momento dell'acquisizione.
  相似文献   
9.
Metabolic adaptation of the chick embryo to chronic hypoxia   总被引:1,自引:0,他引:1  
  相似文献   
10.
Susceptibility to autoimmune insulin-dependent (type 1) diabetes mellitus is determined by a combination of environmental and genetic factors, which include variation in MHC genes on chromosome 6p21 (IDDM1) and the insulin gene on chromosome 11p15 (IDDM2). However, linkage to IDDM1 and IDDM2 cannot explain the clustering of type 1 diabetes in families, and a role for other genes is inferred. In the present report we describe linkage and association of type 1 diabetes to the CTLA-4 gene (cytotoxic T lymphocyte associated-4) on chromosome 2q33 (designated IDDM12). CTLA-4 is a strong candidate gene for T cell- mediated autoimmune disease because it encodes a T cell receptor that mediates T cell apoptosis and is a vital negative regulator of T cell activation. In addition, we provide supporting evidence that CTLA-4 is associated with susceptibility to Graves' disease, another organ- specific autoimmune disease.   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