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   1273篇
  免费   142篇
  国内免费   49篇
耳鼻咽喉   10篇
儿科学   134篇
妇产科学   24篇
基础医学   120篇
口腔科学   45篇
临床医学   104篇
内科学   367篇
皮肤病学   38篇
神经病学   39篇
特种医学   194篇
外科学   73篇
综合类   99篇
预防医学   76篇
眼科学   9篇
药学   69篇
中国医学   3篇
肿瘤学   60篇
  2024年   3篇
  2023年   18篇
  2022年   14篇
  2021年   24篇
  2020年   22篇
  2019年   9篇
  2018年   21篇
  2017年   45篇
  2016年   39篇
  2015年   29篇
  2014年   67篇
  2013年   77篇
  2012年   31篇
  2011年   28篇
  2010年   64篇
  2009年   69篇
  2008年   26篇
  2007年   69篇
  2006年   37篇
  2005年   34篇
  2004年   29篇
  2003年   20篇
  2002年   18篇
  2001年   39篇
  2000年   17篇
  1999年   23篇
  1998年   79篇
  1997年   65篇
  1996年   60篇
  1995年   52篇
  1994年   48篇
  1993年   43篇
  1992年   15篇
  1991年   7篇
  1990年   16篇
  1989年   24篇
  1988年   27篇
  1987年   15篇
  1986年   19篇
  1985年   20篇
  1984年   10篇
  1983年   13篇
  1982年   11篇
  1981年   8篇
  1980年   11篇
  1979年   7篇
  1978年   8篇
  1977年   5篇
  1976年   14篇
  1975年   10篇
排序方式: 共有1464条查询结果,搜索用时 15 毫秒
91.
To determine whether children with recurrent abdominal pain (RAP) include an excess of children with food allergy (FA), this study examined a consecutive series of 84 children (43M, 41F, mean age 7.9 y, range 1.6-15 y) referred during 1 y to 2 university hospitals. In addition to a clinical examination, the patients underwent gastroduodenoscopy with three biopsy specimens, skin-prick and patch tests, and comprehensive laboratory tests for atopic allergy. Based on an open elimination-challenge test, a total of 28 (33%) subjects were diagnosed for FA. In the whole material, specific endoscopic abnormalities were found in 38 (45%) subjects: oesophagitis in 17, gastric erosions in 8, lymphonodular duodenitis in 12 and erosive duodenitis in 5. FA showed a close relationship with duodenal lesions, but no significant association with oesophagitis and gastritis. The histological findings were mild, although some alterations could be observed in up to 66 (79%) subjects, equally often in patients with and without FA. None showed villous atrophy or severe infiltration of eosinophilic or mononuclear cells. Slightly increased densities of eosinophilic cells were significantly associated with endoscopic findings, especially oesophagitis. At least one positive skin-prick test with food allergens was found in 11 subjects and a positive patch test in 21 subjects, but neither showed an association with the endoscopic or histological findings, or even with clinical FA. Conclusion: Since the children with FA showed significantly more often concomitant mucosal pathology of the foregut than those without FA, FA may be considered one of the major factors underlying RAP. The report suggests the trial of an elimination diet in cases with RAP if lymphonodular hyperplasia or duodenitis is seen on gastroduodenoscopy.  相似文献   
92.
36 children aged 0.13 to 13.05 years with severe manifestations of atopy were studied for circulating parietal cell antibodies (PCA), fasting serum gastrin and ferritin. Gastric acid secretion was measured using a pentagastrin test. In addition, 21 gastric and 28 jejunal biopsies were taken for evaluation of the mucosal morphology. In infants the gastric secretion studies were repeated after a three month hypoallergic diet.Maximal acid output (MAO) was significantly (P<0.01) diminished in atopic infants under one year of age. In this group one girl with transient PCA was achlorhydric and seven others were hypochlorhydric, as compared with controls of the same age. Acid secretion returned to normal in most children while on the elimination diet, and only two remained hypochlorhydric thereafter. The picture was more complex in the older children as some continued to exhibit hyposecretion in their second year of life, while others were even hyperchlorhydric. Epithelial degeneration, found in 13 out of the 21 samples, was the most striking feature in the gastric biopsies. Jejunal biopsies revealed increased eosinophilic infiltration of the lamina propria in 10 out of 28 diagnostic samples; two had slight and another two partial villous atrophy.It is concluded that in atopic children gastric hyposecretion and epithelial degeneration may promote the passage of unhandled food allergens through the jejunal mucosa, predisposing to more severe changes, as seen in cow's milk intolerance. Slight villous atrophy with eosinophilic infiltration and oedema of the lamina propria may cause mild absorption defects, growth and nutritional deficiencies in these children. Atopy should be considered as a possible aetiological factor in prolonged gastrointestinal disorders in infants.  相似文献   
93.
The clinical features, the results of gastric secretory function tests, and the duodenojejunal morphology of six infants (aged 0.42–1.23 years) with anemia and melena considered to be due to latent cow's milk intolerance (LCMI) were compared with the findings in nine infants (aged 0.19–0.87 years) with cow's milk-induced malabsorption (CMI). The infants with LCMI had a short period of breast feeding, normal weight gain without symptoms of malabsorption, and no atopic history. The maximal acid secretion was decreased (P<0.01) and the concentration of fasting serum gastrin raised (P<0.01) compared with the controls. Gastric biopsy revealed epithelial degeneration in three and erosion in one out of four samples.The duodenojejunal biopsy revealed slight changes in two samples, the others being normal. The number of eosinophils was increased in four out of six biopsies. Although the number of intraepithelial lymphocytes was increased in LCMI the rise was not as significant as in children with CMI (P<0.05).We conclude from our results that LCMI seems to be a separate clinical entity. The determination of fasting serum gastrin, maximal gastric acid secretion and intraepithelial lymphocytes on duodenojejunal biopsy appear to be helpful in making the diagnosis.  相似文献   
94.
Over 200 measurements of the resting rate of oxygen consumption using an open-circuit method were made on 15 small babies nursed in their usual clinical setting during the first month of life. There were striking and persistent variations between babies that could not be explained by postnatal age, relationship to feed, sleep, or time of day. It was not possible from clinical examination to predict which babies had the higher or lower metabolic rates, except that babies who were light-for-dates generally had higher values. Because of these variations the appropriate thermal temperature for small babies cannot be predicted from average values adjusted for body weight and postnatal age alone.  相似文献   
95.
96.
97.
98.
Trials which randomize practices II: sample size   总被引:3,自引:0,他引:3  
Kerry  SM; Bland  JM 《Family practice》1998,15(1):84-87
BACKGROUND: When practices are randomized in a trial and observations are made on the patients to assess the relative effectiveness of the different interventions, sample size calculations need to estimate the number of practices required, not just the total number of patients. OBJECTIVE: Our aims were to introduce the methodology for appropriate sample size calculation and discuss the implications for power. METHOD: A worked example from general practice is used. DISCUSSION: Designs which randomize practices are less powerful than designs which randomize patients to intervention groups, particularly where a large number of patients is recruited from each practice. Studies which randomize few practices should be avoided if possible, as the loss of power is considerable and simple randomization may not ensure comparability of intervention groups.   相似文献   
99.

Background

Cryptosporidium spp. is a coccidian parasite infected humans and animals. Prevalence rate of Cryptosporidium spp. infection associated with is some parameters such as sampling, age, season, country and contact to domestic animals. This study aimed to determine Cryptosporidium spp. Infection in humans and some animals in rural areas of Shushtar district from Khuzestan Province, south- west of Iran.

Methods

In this study, Stool specimens were randomly collected from 45 cattle, 8 buffalos, 35 calves, 22 turkeys, 3 sheep, 2 geese as well as 62 humans in different seasons selected from rural areas of Shushtar district located in Khuzestan in the south- west of Iran from August 2009 to April 2011. The collected stool samples were examined by modified Ziehl-Neelsen staining method.

Results

Altogether, 68/115 (59.1%) domestic animals and 9/62 (14.5%) of humans were showed Cryptosporidium spp. infection in the study areas.

Conclusion

In this study we found the high frequency of Cryptosporidium spp. infection in the studied areas.  相似文献   
100.
TARO KONO  MD  PHD    BRIAN M. KINNEY  SM  MD    WILLIAM FREDERICK GROFF  DO    HENRY H. CHAN  MD  FRCP    ALI RIZA ERCOCEN  MD    MOTOHIRO NOZAKI  MD  PHD 《Dermatologic surgery》2008,34(S1):S25-S30
BACKGROUND At present, various hyaluronic acids are being used to rejuvenate facial skin. There is no comparative study of single cross-linked hyaluronic acid (SCHA) versus double cross-linked hyaluronic acid (DCHA). The objective of our study is to compare the effectiveness and complications of SCHA versus DCHA in the treatment of glabellar lines.
METHODS Ten female patients were enrolled in this randomized, evaluator-blind study. One side (left vs. right) of each patient's glabellar lines was treated with SCHA and the other side was treated with DCHA. Two independent blinded observers reviewed the clinical photographs at 3, 6, 9, and 12 months after the treatment and assessed for degree of improvement as well as complications.
RESULTS The two products were equally effective in producing an optimal cosmetic result, although at 6, 9, and 12 months posttreatment, a higher proportion of patients showed over 50% improvement with DCHA than with SCHA. At 12 months posttreatment, DCHA was considered superior in 70% of patients, whereas SCHA was superior in 10% of patients.
CONCLUSIONS Both SCHA and DCHA are equally effective in producing an optimal cosmetic result. DCHA provides a more durable esthetic improvement when compared to SCHA in the treatment of glabellar lines.  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