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   1728篇
  免费   94篇
  国内免费   4篇
耳鼻咽喉   40篇
儿科学   73篇
妇产科学   79篇
基础医学   107篇
口腔科学   44篇
临床医学   120篇
内科学   406篇
皮肤病学   43篇
神经病学   57篇
特种医学   41篇
外国民族医学   1篇
外科学   291篇
综合类   44篇
预防医学   90篇
眼科学   59篇
药学   209篇
中国医学   9篇
肿瘤学   113篇
  2023年   9篇
  2022年   61篇
  2021年   87篇
  2020年   41篇
  2019年   78篇
  2018年   79篇
  2017年   63篇
  2016年   52篇
  2015年   51篇
  2014年   61篇
  2013年   84篇
  2012年   137篇
  2011年   126篇
  2010年   62篇
  2009年   69篇
  2008年   73篇
  2007年   76篇
  2006年   58篇
  2005年   45篇
  2004年   28篇
  2003年   30篇
  2002年   22篇
  2001年   35篇
  2000年   20篇
  1999年   21篇
  1998年   15篇
  1997年   9篇
  1996年   21篇
  1995年   13篇
  1994年   7篇
  1992年   11篇
  1991年   19篇
  1990年   10篇
  1989年   17篇
  1988年   26篇
  1987年   25篇
  1986年   15篇
  1985年   10篇
  1984年   10篇
  1983年   7篇
  1979年   14篇
  1978年   10篇
  1977年   11篇
  1976年   17篇
  1975年   8篇
  1974年   11篇
  1973年   9篇
  1972年   9篇
  1967年   6篇
  1966年   10篇
排序方式: 共有1826条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
A new flavonoid from Limonium axillare   总被引:1,自引:0,他引:1  
A new flavonol glycoside identified as myricetin 3-O-beta-D-sorboside (1) has been isolated from the leaves of L. axillare. The new compound showed a moderate inhibition of Ehrlich ascites carcinoma cells.  相似文献   
105.
Anesthetized male Hartley guinea pigs (350-410 g) (n=5) received intratracheally, saline; cadmium (Cd) (0.3 mg); selenium (Se) (0.3 or 0.06 mg); or Cd (0.3 mg) with Se (0.06 mg), per animal. Twenty-four hours later, lungs were evaluated. Bronchoalveolar-lavage fluid of Cd- and/or Se-treated animals varied in their total and differential leukocyte percent population from that of saline control (P<0.05). Cadmium alone or with Se caused high lung to body weight ratios (P<0.05). High lung wet-weight to dry-weight (W/D) ratios (P<0.05) suggestive of lung edema, were evident after Cd and/or Se exposure. Histological examination of Cd- and/or Se-exposed lungs revealed leukocytic infiltration. Results demonstrated that separate or concurrent exposure to noxious metal(s) such as Cd and Se provoke lung edema and injury. Low dose of Se which when instilled alone, although did not result in an increased W/D lung ratio, failed to subside concurrently administered Cd-inflicted damage.  相似文献   
106.
107.
Growth retardation in children with thalassaemia major is multifactorial. We studied the growth hormone (GH) response to provocation by clonidine and glucagon, measured the circulating concentrations of insulin, insulin-like growth factor-I (IGF-I), IGF-binding protein-3 (IGFBP3), and ferritin, and evaluated the spontaneous nocturnal (12 h) GH secretion in prepubertal patients with thalassaemia and age-matched children with constitutional short stature (CSS) (height SDS < -2, but normal GH response to provocation). The anatomy of the hypothalamic pituitary area was studied in patients with abnormal GH secretion using MRI scanning. Children with thalassaemia had significantly lower peak GH response to provocation by clonidine and glucagon (8.8 +/- 2.3 micrograms/l and 8.2 +/- 3.1 micrograms/l respectively) than did controls (17.6 +/- 2.7 micrograms/l and 15.7 +/- 3.7 micrograms/l respectively). They had significantly decreased circulating concentrations of IGF-I and IGFBP3 (68.5 +/- 19 ng/ml and 1.22 +/- 0.27 mg/l respectively) compared to controls (153 +/- 42 ng/ml and 2.16 +/- 0.37 mg/l respectively). Seven of the thalassaemic children had a GH peak response of < 7 micrograms/l after provocation. Those with a normal GH response after provocation also had significantly lower IGF-I and IGFBP3 concentrations than controls. Analysis of their spontaneous nocturnal GH secretion revealed lower mean (2.9 +/- 1.77 micrograms/l) and integrated (2.53 +/- 1.6 micrograms/l) concentrations compared to controls (4.9 +/- 0.29 micrograms/l and 5.6 +/- 0.52 micrograms/l respectively). Five of them had mean nocturnal GH concentration < 2 micrograms/l and four had maximum nocturnal peak below 10 micrograms/l. These data denoted defective spontaneous GH secretion in some of these patients. MRI studies revealed complete empty sella (n = 2), marked diminution of the pituitary size (n = 4), thinning of the pituitary stalk (n = 3) with its posterior displacement (n = 2), and evidence of iron deposition in the pituitary gland and midbrain (n = 7) in those patients with defective GH secretion (n = 9). Serum ferritin concentration was correlated significantly with the circulating IGF-I (r = -0.47, p < 0.01) and IGFBP3 (r = -0.43, p < 0.01) concentrations. These data prove a high prevalence of defective GH secretion in thalassaemic children associated with structural abnormality of their pituitary gland.  相似文献   
108.
Despite regular blood transfusion and desferrioxamine treatment, growth impairment and pubertal delay are commonly seen in children and adolescents with transfusion-dependent thalassaemia and sickle cell disease (SCD). We evaluated growth parameters and sexual maturation in a large cohort of children and adolescents with SCD (n = 110) and thalassaemia (n = 72) receiving nearly the same protocol of transfusion and chelation, and compared them with those for 200 normal age-matched children, 30 children with constitutional delay of growth (CSS), and 25 children with growth hormone deficiency (GHD). Before transfusion, haemoglobin concentration had not been less than 9 g/dl in the past 7 years; desferrioxamine was administered for 7-10 years, including by the intramuscular and subcutaneous routes, three times or more per week. The height standard deviation score (HtSDS), growth velocity (GV) (cm/yr), and growth velocity standard deviation score (GVDSD) of children and adolescents with thalassaemia and SCD were significantly decreased compared to normal children (p < 0.01). Forty-nine per cent of thalassaemic patients and 27 per cent of patients with SCD had HtSDS less than -2, and 83 per cent of thalassaemic patients and 67 per cent of SCD patients had HtSDS less than -1. Fifty-six per cent of thalassaemic children and 51 per cent of children with SCD had GVSDS less than -1. The GV of thalassaemic children was significantly slower than that for children with SCD. Children with thalassaemia and SCD had HtSDS and GVSDS comparable to those for children with CSS but higher than those for patients with GHD. Serum ferritin concentration was correlated significantly with the linear GV in all patients (r = 0.45, p < 0.001). The bone age delay did not differ among the three groups with thalassaemia, SCD and CSS, but the delay was significant in the group with GHD. The mid-arm circumference was significantly smaller in children with thalassaemia and SCD than in normal children. The triceps skin-fold thickness of patients with SCD was significantly decreased compared to thalassaemic and normal children. The upper/lower segment ratio was significantly lower in thalassaemic and SCD patients than in normal children. In thalassaemic patients between the ages of 13 and 21 years a complete lack of pubescent changes was present in 73 per cent of boys and 42 per cent of girls. Seventy-four per cent of the thalassaemic girls had primary amenorrhoea. Girls with SCD aged between 13 and 21 years had markedly delayed breast development and menarche. Twenty-five per cent of boys with SCD above the age of 14 years had absence of testicular development. Males with thalassaemia and SCD who had spontaneous testicular development had significantly smaller testicular volume than did normal controls. Short children with thalassaemia and SCD had significantly decreased serum insulin-like growth factor 1 (IGF-1) concentrations compared to children with CSS. Collectively, these data confirm the high prevalence of impaired growth and pubertal delay/failure in children and adolescents with thalassaemia and SCD. The aetiology of impaired growth includes the contributions of lack of pubertal growth spurt due to delayed/absent puberty, decreased synthesis of IGF-1 which might be secondary to a disturbed GH-IGF-1 axis and/or under nutrition, probably due to the hypermetabolic status of these children. It is suggested that newer protocols of treatment, in addition to optimization of transfusion and chelation requirements, should increase the caloric intake of these patients and properly manage their pubertal delay-failure in order to improve their adult height.  相似文献   
109.
110.
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