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   8938篇
  免费   377篇
  国内免费   79篇
耳鼻咽喉   338篇
儿科学   412篇
妇产科学   402篇
基础医学   588篇
口腔科学   352篇
临床医学   637篇
内科学   1957篇
皮肤病学   227篇
神经病学   657篇
特种医学   355篇
外科学   2062篇
综合类   157篇
一般理论   1篇
预防医学   183篇
眼科学   444篇
药学   327篇
中国医学   23篇
肿瘤学   272篇
  2024年   4篇
  2023年   35篇
  2022年   114篇
  2021年   187篇
  2020年   116篇
  2019年   179篇
  2018年   219篇
  2017年   194篇
  2016年   301篇
  2015年   389篇
  2014年   437篇
  2013年   524篇
  2012年   649篇
  2011年   729篇
  2010年   446篇
  2009年   381篇
  2008年   683篇
  2007年   745篇
  2006年   683篇
  2005年   630篇
  2004年   520篇
  2003年   434篇
  2002年   336篇
  2001年   60篇
  2000年   44篇
  1999年   50篇
  1998年   34篇
  1997年   23篇
  1996年   26篇
  1995年   18篇
  1994年   20篇
  1993年   19篇
  1992年   15篇
  1991年   15篇
  1990年   14篇
  1989年   16篇
  1988年   15篇
  1987年   7篇
  1986年   7篇
  1985年   15篇
  1984年   6篇
  1983年   9篇
  1980年   3篇
  1978年   3篇
  1976年   4篇
  1975年   4篇
  1974年   4篇
  1970年   3篇
  1969年   5篇
  1967年   3篇
排序方式: 共有9394条查询结果,搜索用时 149 毫秒
71.
BACKGROUND: N-acetylcysteine, beta-glucan, and coenzyme Q(10) were shown to have antioxidant and anti-inflammatory effects on reperfusion injury. The aim of our study was to determine and evaluate the effects of these agents on ischemia reperfusion injury of limb. MATERIAL AND METHOD: Forty-four New Zealand white rabbits, all female, weighing between 2.3 to 4.2 (mean 3.8) kg, were used in the study. Four study groups were arranged of 11 animals each, by randomization. The first group was the control group (Group C), the other groups were the Group Q, which was medicated with coenzyme Q10, the Group betaG, which was medicated with beta-glucan, and the Group N, medicated with N-acetylcysteine. After baseline measurements, for the ischemia-reperfusion experiments, common iliac artery was clamped and collateral flow was occluded by a rubber arterial tourniquet wrapped around the thigh at the proximal third of the leg. After 60 min of transient ischemic period, the limb was perfused for 180 min. After perfusion, biopsy was taken from the adductor magnus muscle. Second blood sampling was done after reperfusion period. Blood and tissue analysis were done and evaluated statistically. RESULTS: Baseline and post-reperfusion levels of glutathione peroxidase (GPx), super oxide dismutase (SOD), malonyldialdehyde (MDA), and nitric oxide (NO) changed significantly. While MDA levels increased in the control group, it decreased in the other study groups. The increase in GPx and SOD levels were significant in all groups except the control group. Levels of NO were found to have decreased in the control group, whereas it had increased in the other groups. CONCLUSION: Antioxidant medication may help lowering limb ischemia reperfusion injury. All mentioned medications in our study are shown to be able to have an effective role for preventing ischemia reperfusion injury to some extent through their antioxidant properties.  相似文献   
72.
Although truncus arteriosus is often treated with low mortality and morbidity rates, truncal valve patency and aortic arch and coronary artery anomalies are factors that can contribute to a worse outcome. In this report, we present our experience with the combination of Rastelli and Norwood procedures for the treatment of Type I truncus arteriosus that was complicated by a hypoplastic aortic arch.  相似文献   
73.
Arteriovenous malformation of the foot is very uncommon, and surgical closure after its treatment with embolization and total excision may be challenging for the foot surgeon, particularly in distally localized lesions. A popular method to cover these difficult wounds is free-tissue transfer, which is a highly demanding procedure. Alternatively, distally based regional flaps have been occasionally reported for clinical use in such distant foot defects. Herein, we present a 36-year-old female patient with a diagnosis of arteriovenous malformation arising in the distal medial plantar and dorsal surfaces of the right foot. After surgical resection of the vascular lesion preceded by a misapplied embolization procedure, an extended lateral supramalleolar flap was successfully transferred to the defect area, covering it completely. Functional and aesthetic outcome was satisfactory after 6 months follow-up. Extended lateral supramalleolar flap is a useful and reliable choice for distal foot reconstructions.  相似文献   
74.
The proinflammatory mediator (PIM) levels were assessed in surgically removed samples of herniated cervical intervertebral discs. The objective of this study was to investigate if there is a correlation between the levels of PIMs in disc material and myelopathy associated with cervical intervertebral disc herniation and spondylosis. The role of proinflammatory mediators in the degeneration of intervertebral disc and the inflammatory effects of disc herniations on radicular pain has been previously published. However, the possible relationship between PIMs and myelopathy related to cervical disc herniation and spondylosis has not been investigated before. Thirty-two patients undergoing surgery for cervical disc herniation and spondylosis were investigated. Surgically obtained disc materials, stored at 70 degrees C, were classified into two groups: cervical disc herniation alone or with myelopathy. Biochemical preparation and solid phase enzyme amplified sensitivity immunoassay (ELISIA) analysis of the samples were performed to assess the concentration of mediators in the samples. Very similar values of interleukin-6 were found in both groups whereas the concentrations of mediators were significantly higher in myelopathy group. This study has demonstrated that PIMs are involved in cervical intervertebral disc degeneration with higher concentrations in the samples associated with myelopathy.  相似文献   
75.
BACKGROUND: Distal tibial reconstruction with use of an external fixator when there is bone loss, limb-length discrepancy, and/or ankle instability is associated with many problems. The technique of limb-lengthening, ankle arthrodesis, and segmental transfer over an intramedullary nail has been introduced to overcome these problems. The present study investigates this combined technique. METHODS: Between 2002 and 2005, six patients, who ranged from seventeen to seventy years old, underwent distal tibial reconstruction and ankle arthrodesis with use of a circular external fixator and an intramedullary nail to treat a distal tibial defect following resection for chronic osteomyelitis or tumor or to treat a limb-length discrepancy combined with ankle instability. Functional and radiographic results were evaluated, with use of the criteria described by Paley et al., at an average follow-up of thirty-four months. RESULTS: The mean size of the bone defects in three patients was 5.3 cm (2, 7, and 7 cm), and the mean amount of the limb-shortening in four patients was 5.25 cm (range, 4 to 6 cm). The mean external fixation time was 3.5 months, and the mean external fixator index was 0.57 mo/cm. There was no recurrence of infection in the two patients with osteomyelitis. All six patients had excellent bone results, and the functional results were excellent for two patients and good for four patients. There were four complications, three of which were categorized, according to Paley, as a problem (a difficulty that occurs during lengthening and is resolved without operative intervention) and one that was categorized as an obstacle (a difficulty that occurs during lengthening and needs operative treatment). CONCLUSIONS: The combined technique is an improvement over the classic external fixation techniques of distal tibial reconstruction with ankle arthrodesis. It reduces the duration of external fixation, thus increasing patient acceptance, and it is associated with a low complication rate facilitating more rapid rehabilitation.  相似文献   
76.
BACKGROUND: Acute liver failure (ALF) carries a high mortality unless urgent orthotopic liver transplantation (OLT) is performed on time. Live donors are utilized to treat this irreversible condition first in pediatric cases and then in adults. Herein, we aimed to report our experience with live donors for ALF in a country of a deceased donor organ donation rate is only 1.5 per million people. METHODS: Among the 245 live donor liver transplantations (LDLT) performed from June 1999 to December 2005, 14 of them (6%) were performed for ALF in 8 pediatric and 6 adult cases. Right lobes were harvested for the adult cases whereas left lateral segments were harvested for pediatric cases, except one child transplanted with a right lobe graft. The etiology of the disease was; acute hepatitis B in four cases, hepatitis A in three cases, Wilson disease two cases, autoimmune hepatitis in two cases, and was unknown in three cases. RESULTS: Three-year graft and patient survival is 79% for these series. Five of the six adult patients and six of the eight pediatric cases survived after transplantation. There was not any donor mortality or major morbidity. CONCLUSIONS: LDLT offers a safe and effective modality of treatment for ALF for both pediatric and adult patients to overcome the problem of organ shortage especially in countries where the chance of receiving an organ from a deceased donor is low.  相似文献   
77.
BACKGROUND: Pulmonary complications are the most frequent cause of postoperative morbidity and mortality in upper abdominal surgery (UAS). We aimed to examine the influence of possible preoperative, operative and postoperative risk factors on the development of early postoperative pulmonary complications (POPC) after UAS. METHODS: A prospective study of 60 consecutive patients was conducted who underwent elective UAS in general surgical unit. Each patient's preoperative respiratory status was assessed by an experienced chest physician using clinical examination, chest radiographs, spirometry and blood gas analysis . Anaesthetical risks, surgical indications, operation time, incision type, duration of nasogastric catheter and mobilization time were noted. Forty-eight hours after the operation, pulmonary examinations of the patients were repeated. RESULTS: Postoperative pulmonary complications were observed in 35 patients (58.3%). The most common complication was pneumonia, followed by pneumonitis, atelectasis, bronchitis, pulmonary emboli and acute respiratory failure. The presence of preoperative respiratory symptoms and the spirometric parameter of forced expiratory volume in 1 s/forced vital capacity were the most valuable risk factors for early prediction of POPC. The sensitivity, specificity and diagnostic efficiency of the presence of preoperative respiratory symptoms in the POPC prediction were 70, 61 and 66%, respectively. CONCLUSION: We recommend a detailed pulmonary examination and spirometry in patients who will undergo UAS by chest physicians to identify the patients at high risk for POPC, to manage respiratory problems of the patients before surgery and also to help surgeons to take early measures in such patients before a most likely POPC occurrence. Improvement of lung function in those patients at risk for POPC before operation may decrease morbidity in surgical patients.  相似文献   
78.

Purpose

The aim of this study was to investigate the effects of iloprost (IL) on ischemia-reperfusion injury in a rodent model.

Materials and methods

Twenty-four Wistar Albino rats were randomized into four groups (n = 6). Laparotomy was performed in all groups under general anesthesia. Only laparotomy was applied in group S (Sham). Ischemia-reperfusion group (group I/R) underwent ischemia and reperfusion performed by clamping and declamping of the infrarenal abdominal aorta for 120 min. The iloprost group (group IL) received intravenous infusion of IL 0.5 ng/kg/min, without I/R. Group I/R + IL received intravenous infusion of IL 0.5 ng/kg/min immediately after 2 h period of ischemia. At the end of the reperfusion period, all rats were killed under anesthesia and skeletal muscle samples of lower extremity were harvested for biochemical and histopathologic analyses.

Results

Tissue levels of endothelial nitric oxide were significantly higher in I/R groups than those in groups S and IL. The heat shock protein 60 levels were higher in group I/R than the other groups. But the heat shock protein 60 levels in group I/R + IL were found to be similar with the groups S and IL. Malondialdehyde levels were significantly higher in group I/R. On the other hand, in group I/R + IL, malondialdehyde levels were higher than those in groups S and IL but lower than those in group I/R. Superoxide dismutase (SOD) enzyme activities were found to be significantly lower in group I/R than the other groups. Also in group I/R/I, the SOD enzyme activities were higher than those in group I/R. But, in group I/R + IL, SOD levels were found to be higher than those in group I/R but lower than those in groups S and IL.

Conclusions

These results indicate that IL has protective effects on I/R injury in skeletal muscle in a rodent model.  相似文献   
79.

Background

To investigate the protective effect of 2-aminoethyl diphenylborinate (2-APB) against ischemia–reperfusion (I/R) injury in the rat kidney by an experimental study.

Materials and methods

Thirty male Sprague-Dawley rats were randomly divided into the following three groups: (1) sham group, (2) I/R group, and (3) I/R + 2-APB group. Renal I/R injury was induced by clamping the left renal pedicle for 45 min after right nephrectomy, followed by 3 h of reperfusion. The therapeutic agent 2-APB was administered intravenously at a dose of 2 mg/kg 10 min before renal ischemia. Glutathione, superoxide dismutase, total antioxidant capacity, malondialdehyde, tumor necrosis factor α, interleukin 6, aspartate aminotransferase, alanine aminotransferase, and creatinine levels were measured from blood samples, and the rats were sacrificed subsequently. Tissue samples were scored histopathologically. Visualization of apoptotic cells was performed using the terminal deoxynucleotidyl transferase dUTP nick end labeling staining method.

Results

2-APB significantly reduced serum malondialdehyde, tumor necrosis factor α, interleukin 6, aspartate aminotransferase, alanine aminotransferase, and creatinine levels in the I/R injury group. However, glutathione, superoxide dismutase, and total antioxidant capacity levels increased significantly. Histopathologic scores were significantly better and the rate of apoptosis was lower in the 2-APB group.

Conclusions

2-APB reduces oxidative stress and damage caused by renal I/R injury. The results of this study demonstrate that 2-APB can be used as an effective agent against I/R injury in the kidney.  相似文献   
80.
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