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   2362篇
  免费   141篇
  国内免费   12篇
耳鼻咽喉   30篇
儿科学   137篇
妇产科学   37篇
基础医学   238篇
口腔科学   86篇
临床医学   290篇
内科学   558篇
皮肤病学   27篇
神经病学   209篇
特种医学   236篇
外科学   190篇
综合类   42篇
一般理论   1篇
预防医学   164篇
眼科学   28篇
药学   90篇
  1篇
肿瘤学   151篇
  2022年   11篇
  2021年   24篇
  2020年   22篇
  2019年   24篇
  2018年   37篇
  2017年   40篇
  2016年   34篇
  2015年   48篇
  2014年   45篇
  2013年   78篇
  2012年   90篇
  2011年   91篇
  2010年   81篇
  2009年   91篇
  2008年   96篇
  2007年   70篇
  2006年   75篇
  2005年   90篇
  2004年   71篇
  2003年   63篇
  2002年   61篇
  2001年   52篇
  2000年   44篇
  1999年   44篇
  1998年   100篇
  1997年   98篇
  1996年   97篇
  1995年   68篇
  1994年   62篇
  1993年   54篇
  1992年   46篇
  1991年   48篇
  1990年   28篇
  1989年   54篇
  1988年   55篇
  1987年   52篇
  1986年   42篇
  1985年   43篇
  1984年   33篇
  1983年   32篇
  1982年   24篇
  1981年   24篇
  1980年   17篇
  1979年   17篇
  1978年   21篇
  1977年   21篇
  1976年   15篇
  1975年   14篇
  1973年   8篇
  1971年   10篇
排序方式: 共有2515条查询结果,搜索用时 31 毫秒
71.
72.
该文旨在对小唾液腺癌的治疗进行回顾。小唾液腺癌可发生在头颈部很多位置,通常表现为黏膜下肿块。影像学检查是对肿瘤发病部位及病变范围内解剖结构的关系进行评估的基础。切取活检或穿吸活检可以决定肿瘤的病理类型和分级。随着分子生物学技术的不断进步,小唾液腺癌的诊断  相似文献   
73.

Purpose

To investigate renal ischemia injury during renal hilar clamping (artery alone versus clamping artery/vein together) by evaluating ischemic damage via two different modalities in animal models—near-infrared tissue oximetry and 8-isoprostane levels.

Methods

Near-infrared renal oximetry measurements of Yorkshire swines (n = 4; 8 renal units) subject to hilar clamping were obtained at baseline, during warm ischemia (15- and 30-min trials) and after unclamping. Quantitation of 8-isoprostane levels is the second technique of quantitating interstitial fluid collected from a dialysis catheter placed through renal parenchyma of male Sprague–Dawley rats (n = 50) subject to hilar clamping during preclamp, clamp (either 15 or 30 min of hilum clamping), and post-clamp.

Results

N ear-infrared tissue oximetry. In the 15-min trial, oxygen saturation decreased 6× faster with artery alone compared to artery/vein clamped together. In the 30-min trial, the decrease was 5× faster. Recovery of oxygen saturation with only artery clamped occurred more than 2× faster in the 15- and 30-min periods. Isoprostane. For 15-min clamp times, 8-isoprostane levels in the artery alone group demonstrated a 1.54 decrease in the artery clamped alone group (p = 0.006) versus artery/vein together: preclamp (11.47 and 11.63 pg/mL/g), clamp (14.61 and 17.70 pg/mL/g), and post-clamp (14.26 and 22.04 pg/mL/g).

Conclusions

Renal ischemia injury from clamping the renal artery alone was significantly less than clamping artery/vein together demonstrated in two different techniques. Recovery of oxygen saturation was twofold faster, and mean post-clamp 8-isoprostane levels demonstrated a 1.54-fold decrease with clamping renal artery alone compared to clamping artery/vein together.  相似文献   
74.
Objectives To study whether the degree of carotid atherosclerosis and the male predominance of echolucent plaques could explain the sex difference in myocardial infarction (MI) compared to angina pectoris (AP).

Design Ultrasound examination of the carotid artery was performed in 6727 persons. The presence of plaque, plaque thickness and number of segments with plaque were recorded. Plaque morphology in terms of echogenicity was scored as echolucent (soft plaque) or echogenic (hard plaque). A questionnaire was used to obtain information about coronary heart disease.

Results In men with the most advanced atherosclerosis, the risk (OR, 95% CI) of having MI compared to those with no carotid atherosclerosis was less than half as the corresponding risk in women (2.2, 1.4–3.3 vs 5.3, 2.6–10.6). For MI, the male-to-female ratio was highest in the group with no carotid plaque and declined by increasing burden of atherosclerosis. For AP, the sex ratio was independent of the degree of atherosclerosis.

Conclusions The findings support the hypothesis that the sex difference in MI compared to AP is due to the higher male prevalence of echolucent plaque.  相似文献   
75.
Objectives - To investigate whether impaired fetal growth, measured by low birth weight and short birth length, is linked with raised levels of serum lipids and increased risk and mortality of coronary heart disease. Design - The association between birth length, birth weight, Ponderal Index and total serum cholesterol was examined in 545 Danish men and women aged 31 to 51 years who participated in the Ebeltoft Health Promotion Project in Denmark. Results - No associations were found in women. For men, a negative association was found between birth weight and serum total cholesterol, with a fall in mean serum total cholesterol from 6.03 mmol/l at birth weight below 3300 g to 5.64 mmol/l at birth weight above 4000. A similar association was found between birth length and serum cholesterol, with a mean value of 6.23 mmol/l at birth length below 51 cm and a mean value of 5.56 mmol/l at birth length above 54 cm. No associations were found for Ponderal Index. Between 3% and 8% of the variance in serum total cholesterol could be explained by the statistical models used in this study. Conclusion - Our findings support the hypothesis of a negative association between birth weight, birth length and elevated serum cholesterol in adult life, but only in men.  相似文献   
76.
Background The annual number of total hip arthroplasties (THA) has increased in Denmark over the past 15 years. There is, however, limited detailed data available on the incidence of THAs.

Methods We calculated the incidence rates (IR) of primary THA and revision in Denmark between 1996 and 2002 and estimated the demands for primary THA in Denmark until 2020. We used data from the Danish Hip Arthroplasty Registry, a nationwide and popula-tion-based clinical database, to identify patients who had undergone primary THA (n = 37 144) or revision arthroplasties (n = 6 446). Age and sex-specific data on the Danish population were obtained from the StatBank Denmark. All IRs were standardized according to two standards, i.e. the Danish population in 1996 and the European standard population (18 age groups). The future demands for primary THA were estimated using the age and sex-specific incidence of primary THA for 2002 as a reference, and taking into account the expected changes in the age distribution of the population and the trend in IRs seen in Denmark between 1996 and 2002.

Results The annual overall standardized IRs of primary THAs and revisions increased from 101 (95% confidence interval (CI): 97.6–104) to 134 (CI: 131–138) and from 19.2 (CI: 17.9–20.5) to 21.1 (CI: 19.8–22.4) per 100 000 inhabitants from 1996 to 2002, respectively (IRs adjusted to the Danish population in 1996). The IRs of primary THAs and revisions increased by 30% and 10% during this period. The relative increase in IRs of primary THAs was found to be similar in both women and men. The increase was higher among patients aged 50–59 years, however. Furthermore, a decrease in IRs was seen in patients who underwent primary THA due to rheumatoid arthritis. IRs of primary THAs have been estimated to increase by 22% in 2020 compared with 2002, based only on the expected changes in the age distribution of the population. However, assuming that the annual age and sex-independent increase in the IRs seen in the period 1996–2002 will continue, the IR of primary THA is estimated to increase by as much as 210% in 2020.

Interpretation The overall annual standardized IRs of primary THAs and revisions in Denmark increased during the period from 1996 to 2002. Moreover, the demands for THA procedures in the coming decades may exceed the current capacity due to the ageing population and a continued age and sex-independent increase in surgical activity.  相似文献   
77.
78.
79.
Background: Despite the widespread use of the Impact of Event Scale to measure post-traumatic stress symptoms, psychometric evaluations of the scale have revealed mixed findings. Aim: The aim of the present study is to provide new empirical evidence and examine the factor structure, reliability, and predictive validity of the Norwegian version of the IES-R. Methods: Posttraumatic stress symptoms were recorded in a student sample (n=312) 3 weeks after the Southeast Asian tsunami disaster in December 2004. Confirmatory factor analyses of the IES-R behavior items using structural equation modeling (SEM) were performed on four models from existing research. Results: The original three-factor model of intrusion, avoidance and hyperarousal symptoms exhibited the best goodness-of-fit indices when defined as oblique. The IES-R also revealed satisfactory reliability. Symptom levels of intrusion and avoidance were moderate, while hyperarousal scores were low, with a significant gender difference. Conclusion: Taken together, the IES-R revealed good psychometric properties in this nonclinical student sample and could be a useful instrument to assess and follow-up on PTSD symptoms after a certain identified trauma.  相似文献   
80.
Hold-and-split tasks were performed by 20 subjects (12 females and 8 males) using the right central incisors, canines, 2nd premolars, and 1st molars, respectively. Half a peanut was positioned on a transducer-equipped plate and the subject was instructed to hold the plate with the peanut between two antagonistic teeth, and not using more force than necessary. After ca. 3 s the subject was instructed to split the peanut in a natural manner. Each session consisted of a series of three in which the subject performed the hold-and-split task five times for each tooth. Thus, in total, data were obtained from 60 trials for each subject. The magnitude of the forces and the force rates used to split the peanut increased distally along the dental arch. However, the duration of the split phase was similar for the various teeth examined. During anesthesia of the periodontal ligament (four subjects), no significant changes were seen in the split phase. The forces used to hold the peanut between the teeth also increased distally along the dental arch: 0.60 N for the incisor, 0.77 N for the canine, 1.15 N for the 2nd premolar, and 1.74 N for the 1st molar. The difference in hold forces for the various teeth can be explained by the different sensitivity characteristics of the periodontal afferents innervating anterior and posterior teeth. During periodontal anesthesia, the magnitude and variability of the hold forces increased for all types of teeth, thus supporting the suggestion that periodontal afferent information is used in the regulation of the level of forces used to hold and manipulate morsels between the teeth.  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