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   2665篇
  免费   203篇
  国内免费   10篇
耳鼻咽喉   27篇
儿科学   108篇
妇产科学   53篇
基础医学   371篇
口腔科学   29篇
临床医学   167篇
内科学   634篇
皮肤病学   83篇
神经病学   155篇
特种医学   72篇
外科学   258篇
综合类   216篇
预防医学   336篇
眼科学   33篇
药学   194篇
中国医学   12篇
肿瘤学   130篇
  2023年   25篇
  2022年   18篇
  2021年   83篇
  2020年   45篇
  2019年   62篇
  2018年   66篇
  2017年   49篇
  2016年   67篇
  2015年   90篇
  2014年   109篇
  2013年   143篇
  2012年   179篇
  2011年   165篇
  2010年   102篇
  2009年   63篇
  2008年   136篇
  2007年   118篇
  2006年   118篇
  2005年   110篇
  2004年   95篇
  2003年   97篇
  2002年   101篇
  2001年   75篇
  2000年   78篇
  1999年   68篇
  1998年   21篇
  1997年   29篇
  1996年   23篇
  1995年   19篇
  1994年   16篇
  1993年   17篇
  1992年   39篇
  1991年   39篇
  1990年   28篇
  1989年   27篇
  1988年   26篇
  1987年   18篇
  1986年   28篇
  1985年   23篇
  1984年   19篇
  1979年   15篇
  1976年   14篇
  1975年   12篇
  1974年   18篇
  1973年   32篇
  1972年   11篇
  1970年   11篇
  1969年   11篇
  1968年   11篇
  1967年   11篇
排序方式: 共有2878条查询结果,搜索用时 786 毫秒
1.
2.
3.
Seventy seven antral biopsies were collected from patients attending endoscopy clinic at King Khalid University Hospital, Riyadh, Saudi Arabia during a period of six months between December 1988 to May 1989. Of these 69 (89.6%) showed chronic gastritis as well as Helicobacter-like organisms (HLOs) in the biopsy specimens while 63 (81.8%) of biopsies grew Helicobacter pylori on culture. These findings indicate a good correlation between the histological diagnosis of chronic gastritis and isolation of H. pylori on culture.  相似文献   
4.
5.
L Agius  M H Chowdhury  S N Davis  K G Alberti 《Diabetes》1986,35(11):1286-1293
The metabolic actions of porcine insulin and biosynthetic human proinsulin on fatty acid and glucose metabolism were studied in rat hepatocytes cultured in monolayer for 24 h. Our aim was to establish whether proinsulin action in the liver is similar to insulin action and whether the relative potencies of the two hormones are the same for different metabolic processes. Proinsulin and insulin exerted a similar maximal inhibitory effect on ketone body formation from palmitate and on gluconeogenesis from pyruvate. The half-maximal effective concentration of proinsulin was 11-13 times that of insulin. The antiketogenic effects of insulin and proinsulin were associated with an increased glycerol 3-phosphate content and a decreased affinity of carnitine palmitoyltransferase for its substrate palmitoyl-CoA. When the basal rate of ketogenesis was increased with isobutyl methylxanthine, the half-maximal effective concentrations of both proinsulin and insulin were decreased, but the relative potency of the two hormones was unchanged. Proinsulin and insulin exerted similar maximal stimulatory effects on glycogen synthesis and on the activities of pyruvate kinase, glucose 6-phosphate dehydrogenase, phosphogluconate dehydrogenase, and malic enzyme. The half-maximal effective concentration of proinsulin was 10-30 times that of insulin. These findings are consistent with receptor binding studies on liver membranes that suggest that proinsulin interacts with insulin-specific and not proinsulin-specific receptors. Our findings also suggest that proinsulin action does not differ from insulin action at a postreceptor site.  相似文献   
6.
BACKGROUND: Epinephrine injected by an autoinjector in the anterolateral aspect of the thigh is the standard of care in the emergency self-treatment of anaphylaxis. In the United States, the autoinjector EpiPen is widely used for the self-treatment of anaphylaxis. OBJECTIVE: To investigate whether EpiPen autoinjector, with a needle length of 1.43 cm, is sufficient for intramuscular delivery of epinephrine in men and women. METHODS: The distance from skin to muscle in the anterolateral aspect of the thigh was measured in 50 men and 50 women who had undergone computed tomography of the thighs for other medical reasons. For each individual, body mass index (BMI; a measure of weight in kilograms divided by the square of height in meters) was also calculated, and the individuals were classified as underweight (BMI, < 18.5), normal (BMI, 18.5-24.9), overweight (BMI, 25.0-29.9), and obese (BMI, > or = 30.0) using standard definition. RESULTS: In the study participants the mean +/- SD distance from skin to muscle was 0.66 +/- 0.47 cm for men and 1.48 +/- 0.72 cm for women (P < .001). One man (obese at a BMI of 42.2) and 21 women (11 obese with a mean BMI of 35.2, 6 overweight with a mean BMI of 30.1, and 4 normal with a mean BMI of 24.5) had a greater distance from skin to muscle than the EpiPen needle length of 1.43 cm. CONCLUSION: The distance from skin to muscle for the anterolateral aspect of the thigh is higher in women compared with men. This difference suggests that EpiPen may not deliver epinephrine to the intramuscular tissue in many women.  相似文献   
7.
8.
It is posited that diarrhoeal illness during one period has influence on diarrhoeal illness in a subsequent period. This relationship may potentially mask the association between malnutrition and subsequent diarrhoea. To test this, we analysed data on cross-sectional anthropometry in combination with data on diarrhoeal morbidity collected longitudinally in a community-based study of 1262 children (aged 6-60 months) during March-December, 1976, in Matlab, Bangladesh. The results confirmed the posited relationship between diarrhoeal morbidities in two consecutive periods and showed that the risks of diarrhoeal attack and longer diarrhoeal illness increased more than threefold during the 2 months following diarrhoeal illness during the preceding 2 months (previous diarrhoea). Children with no previous diarrhoea indicated a positive association between malnutrition and subsequent diarrhoea, but the pattern found among children with previous diarrhoea was not understandable. Logistic regression analyses performed separately for younger and older children showed that controlling for effects of previous diarrhoea, maternal illiteracy and household poverty, severe malnutrition as assessed by weight-for-age was found to be strongly associated with the risk of longer diarrhoeal illness in a 2-month interval in the age group 24-60 months; in the same age group the association with the risk of diarrhoeal attack was significant at the 10 per cent level. No such association for malnutrition, however, was found in the age group 6-23 months.  相似文献   
9.
The serum ceruloplasmin concentration was determined in cancer patients before and after radiotherapy, and after relapse of cancer, The ceruloplasmin concentration in patients who responded to therapy, decreased to the range of normal controls. In patients who did not respond to treatment, the ceruloplasmin concentration was more or less elevated. In patients with relapse of cancer, the ceruloplasmin concentration was higher than before treatment.  相似文献   
10.
Recent investigations have shown that the calcium channel blocker verapamil attenuated the hypoxic ventilatory chemosensitivity of carotid body in animals. To determine whether this is also the case in humans, transient physiological chemodenervation by O2 breaths (withdrawal test) during sustained hypoxia (N = 7), and ventilatory and circulatory responses to progressive hypoxia and hypercapnia (N = 8) were examined after oral administration of verapamil. During sustained hypoxia after verpamil, there was a significant reduction of withdrawal response from 5th to 25th min value (p < 0.01), but not after placebo. On the other hand, no significant difference in ventilatory responses to progressive hypoxia and hypercapnia was observed after verapamil. Verapamil run reveals similar features with placebo run in circulatory parameters except blood pressure response, which tended to be suppressed by verapamil. We conclude that verapamil attenuates peripheral chemoreceptor activity with time during sustained mild hypoxia in normal adult humans and this may be explained by delayed depletion in intracellular Ca2+ for chemotransduction of the peripheral chemoreceptors.  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