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   689篇
  免费   20篇
  国内免费   5篇
耳鼻咽喉   15篇
儿科学   39篇
妇产科学   28篇
基础医学   44篇
口腔科学   41篇
临床医学   46篇
内科学   158篇
皮肤病学   7篇
神经病学   53篇
特种医学   20篇
外科学   191篇
综合类   4篇
预防医学   17篇
眼科学   19篇
药学   22篇
中国医学   2篇
肿瘤学   8篇
  2024年   1篇
  2023年   2篇
  2022年   3篇
  2021年   14篇
  2020年   12篇
  2019年   17篇
  2018年   17篇
  2017年   10篇
  2016年   17篇
  2015年   27篇
  2014年   39篇
  2013年   46篇
  2012年   57篇
  2011年   58篇
  2010年   28篇
  2009年   19篇
  2008年   47篇
  2007年   58篇
  2006年   54篇
  2005年   43篇
  2004年   41篇
  2003年   29篇
  2002年   22篇
  2001年   11篇
  2000年   13篇
  1999年   2篇
  1998年   2篇
  1997年   3篇
  1996年   3篇
  1995年   5篇
  1994年   1篇
  1993年   2篇
  1992年   3篇
  1991年   3篇
  1990年   1篇
  1988年   2篇
  1981年   1篇
  1980年   1篇
排序方式: 共有714条查询结果,搜索用时 15 毫秒
1.
Age determines memory for face identity and expression   总被引:1,自引:1,他引:0  
Background: The recognition of facial expressions is an important component of emotion processing which contributes to interactional behavior. One of the factors highly associated with potential decline of ability in behavioral tasks is age. Methods: We have investigated age‐related changes in facial identity and expression memory of healthy subjects in three age groups: young adults (20–40 years), elderly adults (60–80 years) and, for the first time in the literature, very old adults (over 80 years of age). Using a picture test, photographs of faces with happy or angry expressions were presented to study participants during the encoding task, and the memory for identity and emotional facial expression was investigated in a subsequent recognition task showing emotionally neutral faces. Half of the faces presented in the recognition task were initially shown in the encoding task. Results: Age interacted with the memory process: the ability to recognize both facial identity and emotional expression declined with advanced age. Happy facial expressions were better recognized in all age groups. Although there was a continuous overall decrease in recognition of both happy and angry expressions with advanced age, the effect favoring happy facial expressions was stable also in very old adults. Other factors such as gender or educational level did not affect the memory process for facial expressions. Conclusions: Our findings suggest that age is a significant determinant of memory for facial identity and emotional expression, and that, similar to younger adults, the recognition process of the elderly favors happy emotional facial expressions.  相似文献   
2.
The isolated fourth ventricle (IFV) develops in which obstruction to the out flow of cerebrospinal fluid from the choroid plexus of the fourth ventricle occurs rostrally and caudally. IFV has been a rare occurrence and is difficult to treat. We had an occasion to admit a 28-year-old female to our hospital due to hydrocephalus: she also had a history of meningitis a year ago. The patient was initially managed by a lateral ventriculo-peritoneal shunting procedure. Six months after the procedure the patient began to suffer from vomiting, nausea, and diplopia. CT and MRI scans demonstrated an isolated fourth ventricle enlargement; and thus, a fourth ventriculo-peritoneal shunting procedure was performed under stereotactic conditions. The authors present a case of an isolated fourth ventricle after lateral ventriculo-peritoneal shunting for hydrocephalus, which was treated with a stereotactically guided fourth ventriculo-peritoneal shunting procedure. The technique of this procedure is described below.  相似文献   
3.
A case of synovial chondromatosis of the proximal tibiofibular joint in addition to lateral and medial tibiofemoral spaces and patellofemoral joint has been presented.  相似文献   
4.
5.
OBJECTIVES: Orexins A and B are neuropeptides involved in the regulation of feeding behavior, energy homeostasis and arousal. In the human retina, however, immunohistochemical localization of orexins and their receptors, OX-R1 and OX-R2, has not been ascertained. METHODS: We localized orexins A and B, OX-R1 and OX-R2 in the human retina using immunohistochemistry. Retinae from 2 Alzheimer's disease (AD) patients provided preliminary evidence for possible orexin alterations. RESULTS: Orexin A, orexin B and OX-R1 were localized in ganglion and amacrine cells, cellular processes in the inner and outer plexiform layer and in the inner segments of photoreceptor cells. There was no OX-R2 immunoreactivity in the retina. The staining intensity for both orexins was decreased in the AD patients. CONCLUSION: This immunohistochemical study provides the first evidence for the distribution of orexin A, orexin B and OX-R1 in the human retina. The localization pattern suggests a modulatory role for orexins in the interactions of those retinal cells which transmit light information to the suprachiasmatic nuclei, and thus may be involved in circadian rhythm entrainment.  相似文献   
6.
Pharmacokinetic models for ethanol metabolism have contributed to the understanding of ethanol clearance in human beings. However, these models fail to account for ethanol's toxic metabolite, acetaldehyde. Acetaldehyde accumulation leads to signs and symptoms, such as cardiac arrhythmias, nausea, anxiety, and facial flushing. Nevertheless, it is difficult to determine the levels of acetaldehyde in the blood or other tissues because of artifactual formation and other technical issues. Therefore, we have constructed a promising physiologically based pharmacokinetic (PBPK) model, which is an excellent match for existing ethanol and acetaldehyde concentration-time data. The model consists of five compartments that exchange material: stomach, gastrointestinal tract, liver, central fluid, and muscle. All compartments except the liver are modeled as stirred reactors. The liver is modeled as a tubular flow reactor. We derived average enzymatic rate laws for alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH), determined kinetic parameters from the literature, and found best-fit parameters by minimizing the squared error between our profiles and the experimental data. The model's transient output correlates strongly with the experimentally observed results for healthy individuals and for those with reduced ALDH activity caused by a genetic deficiency of the primary acetaldehyde-metabolizing enzyme ALDH2. Furthermore, the model shows that the reverse reaction of acetaldehyde back into ethanol is essential and keeps acetaldehyde levels approximately 10-fold lower than if the reaction were irreversible.  相似文献   
7.
The potential role of Iloprost, a stable analogue of prostocyclin, in treating spinal cord ischemia was investigated in rabbits subjected to aortic occlusion for 15 minutes. Ten adult rabbits weighing 2-2.5 kg received an intravenous infusion of saline (SF) as a control group and 14 rabbits received an intravenous infusion of Iloprost, 25 microg/kg/h. Iloprost infusion was started immediately after clamping of the aorta and continued 60 minutes thereafter. Cortical somatosensorial evoked potentials (CSEP) were recorded during the pre-ischemic period as a baseline and post-ischemic readings were taken at 15, 30 and 60 minutes. There was no statistically significant difference between CSEP of the saline and Iloprost treated groups (p < 0.05). All animals were examined neurologically by using a modification of Tarlov scale and all subjects were then deeply anesthetized and their spinal cords were removed for light and electron microscopic examinations at 24 h after spinal cord ischemia. In order to obtain an accurate comparison of ultrastructural changes between saline treated and Iloprost treated groups, a grading scale was performed. The light microscopic and ultrastructural analysis of the Iloprost treated group revealed that there was moderate protection of the myelin and axons and edema was attenuated. Findings of this study suggest that Iloprost exerts a protective effect on spinal cord ischemia. However, further studies are needed to reveal possible mechanisms of protection provided by Iloprost.  相似文献   
8.
Summary  The aim of this study is to find out the effects of different doses of midazolam, when used epidurally, on somatosensory evoked potentials (SEP) by delaying neuronal conduction. Thirty two New Zeland albino male rabbits were divided into four groups. All rabbits were anesthetised with ketamine and xylasine combination and atracurium was used as muscle relaxant. 10 mg/kg/hr ketamine infusion was used for maintenance of anesthesia. After insertion of the epidural catheter surgically; Group 1 received 1.5 ml isotonic saline (Control), Group 2 received 150 μg/kg, Group 3 received 250 μg/kg, and Group 4 received 500 μg/kg midazolam epidurally. With the stimulation of sciatic nerve, SEP records were recorded from the epidural space. Records were received before the injection of the drug, and 20, 40, 60 minutes after injection of the drug.  “Latancy” results were increased according to control in all groups (including isotonic saline-control-group). Increase in latancy in the control group was interpreted as due to the effect of temperature mismatch of the saline and the rabbits. While in the first and second group amplitudes showed no differences, group 3 and 4 showed decreases of up to 50%. Epidurally administered midazolam up to 150 μg/kg caused no change in SEP records, but 250 and 500 μg/kg doses caused decreases in SEP records which can lead to misinterpretation as neurological damage.  相似文献   
9.
Intraoperative ultrasound has been using to achieve a proper resection strategy in patients undergoing a hepatic colorectal metastasectomy. This study aims to describe and reveal the place of stereotactic metastasectomy in nonpalpable colorectal liver metastases (CLM). A chart review was initiated for all patients underwent resection for CLM between 2006 and 2011. The data concerning perioperative data and intraoperative strategy were abstracted. Among the 58 patients, who underwent a resection for CLM, 4 (6.9 %) (all men, median age 65.5, range 49–72, years) necessitated a stereotactic metastasectomy. Preoperative evaluations showed 1 (n = 1), 2 (n = 2), or 3 (n = 1) lesions, and intraoperative ultrasound (IUS) found an additional lesion in a case. Stereotactic marking was performed for nonpalpable lesions located in segments IVA, II, and VI and at the junction of segments V and VI. The margins were negative for all lesions both resected with conventional and stereotactic techniques. The examinations of the stereotactic resection materials revealed metastatic adenocarcinoma (patients n = 2), focal nodular hyperplasia (n = 1), and abnormal benign liver histology probably induced by chemotherapy (n = 1). The median (range) operation and hospitalization periods were 217.5 (150–310) minutes and 5.5 (2–9) days. No complications were observed except biliary fistula in a case, which spontaneously disappeared within 2 weeks. A patient died due to systemic disease including hepatic metastases 33 months after the liver surgery. Stereotactic metastasectomy may be feasible for the removal of nonpalpable CLM. Further evaluations are necessitated to understand the accurate place of this novel technique.  相似文献   
10.
The correlation of coronary artery disease (CAD) with pro-oxidant/antioxidant balance and oxidative DNA damage was investigated.Seventy-seven patients with CAD and 44 healthy individuals as control were included in this study. The comparative ratios of ubiquinol-10/ubiquinone-10, 8-hydroxy-2''-deoxyguanosine/deoxyguanosine and the level of MDA measured by HPLC and the activities of GPX and SOD by colorimetric approach in blood samples obtained from patients with CAD were unraveled.8-OHdG/dG ratios, serum MDA level and GPX activity were found significantly elevated level in serum of CAD patients compared to control group. The SOD activity was observed in stable levels in CAD patients. Ubiquinol-10/ubiquinone-10 ratio was significantly lower in patients with CAD than the controls.The positive correlation was observed between 8-OHdG/dG ratios in both MDA levels and GPX activity, while the significant negative correlation was seemed between the ratio of 8-OHdG/dG and ubiquinol-10/ ubiquinone-10 as well as MDA levels and ubiquinol-10/ ubiquinone-10 ratio.We conclude that, both the disruption of pro-oxidant/antioxidant balance and oxidative stress in DNA may play an important role in the pathogenesis of coronary artery disease.  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