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   710篇
  免费   44篇
  国内免费   7篇
耳鼻咽喉   1篇
儿科学   41篇
妇产科学   17篇
基础医学   97篇
口腔科学   35篇
临床医学   51篇
内科学   130篇
皮肤病学   23篇
神经病学   12篇
特种医学   145篇
外国民族医学   1篇
外科学   39篇
综合类   51篇
预防医学   47篇
眼科学   7篇
药学   25篇
中国医学   5篇
肿瘤学   34篇
  2024年   3篇
  2023年   3篇
  2022年   4篇
  2021年   11篇
  2020年   11篇
  2019年   11篇
  2018年   17篇
  2017年   13篇
  2016年   19篇
  2015年   13篇
  2014年   20篇
  2013年   39篇
  2012年   28篇
  2011年   20篇
  2010年   46篇
  2009年   45篇
  2008年   27篇
  2007年   23篇
  2006年   12篇
  2005年   11篇
  2004年   5篇
  2003年   5篇
  2002年   3篇
  2001年   5篇
  2000年   5篇
  1999年   7篇
  1998年   34篇
  1997年   33篇
  1996年   34篇
  1995年   35篇
  1994年   23篇
  1993年   21篇
  1992年   4篇
  1991年   4篇
  1990年   7篇
  1989年   15篇
  1988年   14篇
  1987年   10篇
  1986年   13篇
  1985年   9篇
  1984年   12篇
  1983年   14篇
  1982年   12篇
  1981年   13篇
  1980年   15篇
  1979年   4篇
  1978年   8篇
  1977年   2篇
  1976年   8篇
  1975年   5篇
排序方式: 共有761条查询结果,搜索用时 0 毫秒
751.
752.
753.
Hunteria umbellata (K. Schum.) Hallier f. (family: Apocynaceae) is reputed for the folkloric management of labour, pain and swellings, stomach ulcers, diabetes, obesity, and anaemia, with no scientific report of its toxicity and reversibility profile. The present study was, therefore, aimed at investigating the in vivo toxicity and reversibility profile of the aqueous seed extract of Hunteria umbellata (HU). The acute oral and intraperitoneal toxicity studies of HU were determined in Swiss albino mice while its 90-day oral toxicity and toxicity reversibility profile on anthropometric, biochemical, haematological and histopathological parameters were also assessed using standard procedures. Results showed that the LD50 values for the acute oral and intraperitoneal toxicity studies for HU were estimated to be 1000 mg/kg and 459.3 mg/kg, respectively. Visible signs of immediate and delayed toxicities including starry hair coat, respiratory distress, and dyskinesia were observed. For the chronic oral toxicity study, HU administered for 90 days produced significant (p<0.001) reductions in the weight gain pattern and significant (p<0.001) and dose related increases in the relative weights of liver, stomach, spleen, testis, lungs and heart, at the 100 and 500 mg/kg of HU. Chronic HU treatment also produced significant (p<0.05, p<0.001) dose related reductions in the serum levels of fasting blood glucose, bicarbonate, urea and creatinine while causing non-significant (p>0.05) alterations in the serum levels of sodium, potassium, alaninine transaminase, aspartate transaminase, alkaline phosphatase, total and conjugated bilirubin, total protein and albumin. Also, chronic oral treatment with HU produced significant (p<0.05, p<0.01, p<0.001) and dose-related increases in the red cell count, packed cell volume, haemoglobin concentration, platelet count, total leucocyte count and lymphocyte differential while producing significant (p<0.05) reductions in neutrophil and granulocyte differentials. HU also produced histological features of proliferations of the stomach epithelia, lung tissues, splenic white and red pulps, and testicular spermatogenic series. Following 14 days of oral toxicity reversibility test, there was no significant (p>0.05) reversal in the serum levels of the biochemical and haematological parameters investigated, including the HU-induced histological lesions.Overall, results of this study showed that HU has a relatively low oral toxicity profile but its prolonged use, particularly, at high doses should be with great caution.Key words: Hunteria umbellata, Toxicity and reversibility profile, Haematology, Liver and Renal function tests, Histopathology, Rodents  相似文献   
754.
Objective: The aim of this study is to assess the correlation between traditional cardiovascular risk factors and elevated plasma tHcy level in Nigerian hypertensive. Methods: Thirty-six hypertensive patients were recruited with 36 age and sex-matched controls. The age, sex and anthropometric measurements including height, weight and body mass index (BMI) were taken. Plasma total cholesterol, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), triglycerides and tHcy were analyzed. The results of the two groups were compared. Results: The mean total cholesterol and LDL- C were significantly higher in the subjects than in the controls (P = 0.01 and 0.03 respectively). On the other hand, means of HDL-C and triglycerides were not significantly different between the two groups (P =0.06 and 0.68 respectively). Mean total plasma tHcy was ( 12.95 ±4.9) μmol/L in hypertensive patients when compared with ( 11.29 ±3.6) μmol/L in the controls (P = 0.09) , however the mean tHcy was significantly higher in hypertensive patients who had stroke or myocardial infarction than those without these complications (one way Anova F = 3.63, P = 0.04). Significant positive correlation was seen between tHcy and systolic blood pressure, diastolic blood pressure, BMI and LDL-C. Conclusion : The study suggests that elevated plasma tHcy may predict occurrence of cardiovascular complications in hypertensive individuals.  相似文献   
755.

Introduction  

Extracorporeal membrane oxygenation (ECMO) is a supportive cardiopulmonary bypass technique for babies with acute reversible cardiorespiratory failure. We assessed morbidity in ECMO survivors at the age of five years, when they start primary school and major decisions for their school careers must be made.  相似文献   
756.
Aim:  To report the stability of parent-perceived child irregular eating from 6 months to 14 years of age and to investigate a predictive model inclusive of child and parent factors.
Methods:  Of the 7223 singleton children in a birth cohort, 5122 children were re-interviewed at 5 years and 4554 for the 14-year analysis. Information was obtained from structured interviews including questions answered by parents of the child at birth, 6 months, 5 years and 14 years; and by teenagers at age 14 years and from physical measures of the child. The mother's perception that the child was an irregular eater at age 14 years was the major outcome variable of interest.
Results:  Approximately 40% of irregular eaters at age 5 will still be irregular eaters at age 14 years. This was not related to maternal education or socio-economic class. Significant at multivariate analysis were infant feeding problems and the children's ability to regulate their sleep and mood. Significant maternal factors were greater age, not feeling positive about the baby and persistent maternal anxiety during the child's early years.
Conclusion:  Irregular eating behaviour displays considerable continuity from childhood to mid-adolescence. Independent contributions to this behavioural phenotype include child biological and psychological factors and maternal anxiety during the child's early years.  相似文献   
757.
A simple co-culture bioassay system was used to investigate whether or not the anatomical origin affected the ability of epithelial cells from the human uterine (Fallopian) tube to 'bind' spermatozoa. This study was also used to identify some of the factors which may be involved in the regulation of sperm-epithelial interactions in vitro by comparing different tissue culture models and assessing the effect of oestradiol concentration. Epithelial explants harvested from different regions of human uterine tubes were co-incubated with a known concentration of motile donor spermatozoa. All results were adjusted to reflect a standard sperm concentration of 5 x 10(6)/ml. More spermatozoa associated per field of isthmic compared to ampullary epithelium [isthmus 9.5 +/- 0.9, ampulla 7.1 +/- 0.7 (mean +/- SEM); n = 36, P < 0.05, ANOVA] and cells from post-menopausal patients had an apparently reduced ability to bind spermatozoa [isthmus 5.5 +/- 2.0, ampulla 4.3 +/- 1.4 (mean +/- SEM); n = 4]. Neither menstrual cycle stage nor addition of mid-cycle concentrations of 17beta-oestradiol (750 pmol/l) affected the number of spermatozoa which bound to epithelium from either tubal region. In addition, the number of spermatozoa which bound per field of polarized explants was greater (P < 0.05) than that bound to dissociated primary and passaged epithelial cell monolayers. This report is the first to provide evidence suggestive of a role for sperm- epithelial binding in the formation of an isthmic sperm reservoir in the human uterine tube. Results also indicate that oestrogen is not involved in the regulation of these interactions, and that cell polarity is an important factor for such associations in vitro.   相似文献   
758.
Background: Genetic and environmental influences on anthropometric measures can be investigated by comparing dizygotic (DZ) versus monozygotic (MZ) twins. Investigating cohorts living in different geographical areas across the globe can identify the variation in heritability versus environment.

Aims: (1) To investigate the association between birth weight and anthropometric measurements during adulthood; (2) to study the genetic and environmental influences on body measures including birth weight, weight and height among twins; and (3) to assess the variation in heritability versus environment among two cohorts of twins who lived in different geographical areas.

Subjects and methods: Twins were collected from two twin registers. Data on birth weight, adult weight and height in 430 MZ and 170?DZ twins living in two geographically distinct parts of the world were collected. A genetic analysis was performed using MX software.

Results: Birth weight was associated with weight, height and BMI. Both MZ and DZ twins with low birth weight had shorter height during their adult life (p?=?0.001), but only MZ twins with lower birth weight were lighter at adulthood (p?=?0.001). Intra-pair differences in birth weight were not associated with differences in adult height (p?=?0.366) or weight (p?=?0.796). Additive genetic effects accounted for 53% of the variance in weight, 43% in height and 55% in birth weight. The remaining variance was attributed to unique environmental effects (15% for weight, 13% for height and 45% for birth weight and only 16% for BMI). Variability was found to be different in the two cohorts. The best fitting model for birth weight and BMI was additive genetic and non-shared environment and for weight and height was additive genetic, non-shared environment (plus common Environment).

Conclusions: Data suggests that the association between weight at birth and anthropometric measures in later life is influenced by both genetic and environmental factors. Living in different environments can potentially relate to variation found in the environment.  相似文献   
759.

Background

Perception of midline diastema differs among individuals and cultures. To some, it is a feature of beauty, while to others it is aesthetically appalling. From a scientific point of view, midline diastema is a deviation from normal adult dentition. It is not uncommon among some African natives to find individuals demanding for artificially created midline diastema from dental practitioners.

Objective

To present a rare case of pulpal necrosis involving maxillary and mandibular central incisors as a result of poorly executed teeth modification in a bid to create upper and lower midline diastemata.

Result

A 23-year old lady presented with history of spontaneous, sharp, persistent pain associated with palatal swelling and discharging sinus of two weeks duration in relation to maxillary central incisors (11, 21). The complaint was preceded by a history of recurrent pain in relation to 11, 21, 31 and 41 which started soon after obtaining artificially created maxillary and mandibular midline diastemata from a dental quack. Periapical x-ray revealed periapical radiolucency in relation to 21 and 41. Vitality test confirmed necrotic pulp in the lower central incisors. The affected teeth were scheduled for root canal therapy (RCT) and porcelain fused to metal crown. The RCT of 11 and 21 had been completed but further treatment stalled due to financial constraint.

Conclusion

This is a case of obsession for midline diastema, poor dental health education, and illegal dental practice.  相似文献   
760.
BACKGROUND: The study aimed to determine whether allergic conditions accompany analgesic intolerance. METHODS: A total of 132 analgesic-intolerant patients with bronchial asthma admitted to the adult allergy unit from January 1991 to October 1997 and 103 patients with bronchial asthma randomly selected from among the asthmatics referred to our department between January and October 1997 were enrolled in the study. Those having analgesic intolerance and bronchial asthma were accepted as group I; patients having only asthma were accepted as group II. A standard questionnaire was completed for all the patients. Physical examination, routine skin prick tests, determination of total IgE levels and blood type, and oral analgesic provocation tests were also performed. RESULTS: The results showed that some allergic conditions were significantly more common in group I (22.7% and 7.8% for food allergy/intolerance [P<0.05], 16.7% and 7.8% for antibiotic allergy, 16.7% and 2.9% for dermographism, 9.8% and 1.0% for metal allergy, and 9.1% and 1.0% for chronic urticaria for groups I and II, respectively [P<0.001]). In addition, the mean of the total IgE level in the serum was higher in group I than group II (77.6 and 53.7 IU/ml; P<0.05), and the cumulative analgesic consumption was more in group I (14.2+/-17.1 and 9.1+/-12.5 boxes; P<0.05). CONCLUSIONS: Dermographism; chronic urticaria; antibiotic, metal, and food allergy; high levels of total IgE; and a high amount of cumulative analgesic consumption may be the conditions accompanying analgesic intolerance in asthmatics.  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