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   5091篇
  免费   218篇
  国内免费   51篇
耳鼻咽喉   17篇
儿科学   69篇
妇产科学   166篇
基础医学   542篇
口腔科学   56篇
临床医学   330篇
内科学   1527篇
皮肤病学   97篇
神经病学   363篇
特种医学   315篇
外科学   786篇
综合类   20篇
预防医学   108篇
眼科学   120篇
药学   224篇
中国医学   22篇
肿瘤学   598篇
  2023年   29篇
  2022年   43篇
  2021年   116篇
  2020年   58篇
  2019年   78篇
  2018年   137篇
  2017年   109篇
  2016年   115篇
  2015年   112篇
  2014年   143篇
  2013年   229篇
  2012年   329篇
  2011年   326篇
  2010年   219篇
  2009年   171篇
  2008年   306篇
  2007年   346篇
  2006年   329篇
  2005年   350篇
  2004年   373篇
  2003年   320篇
  2002年   312篇
  2001年   76篇
  2000年   47篇
  1999年   61篇
  1998年   86篇
  1997年   58篇
  1996年   74篇
  1995年   42篇
  1994年   37篇
  1993年   35篇
  1992年   32篇
  1991年   38篇
  1990年   32篇
  1989年   25篇
  1988年   15篇
  1987年   24篇
  1986年   14篇
  1985年   15篇
  1984年   12篇
  1983年   10篇
  1982年   4篇
  1981年   4篇
  1980年   4篇
  1979年   6篇
  1978年   9篇
  1975年   7篇
  1970年   5篇
  1968年   8篇
  1967年   7篇
排序方式: 共有5360条查询结果,搜索用时 31 毫秒
1.
Context: We sought to describe our experience with the Hybrid Assistive Limb® (HAL®) for active knee extension and voluntary ambulation with remaining muscle activity in a patient with complete paraplegia after spinal cord injury.

Findings: A 30-year-old man with complete paraplegia used the HAL® for 1 month (10 sessions) using his remaining muscle activity, including hip flexor and upper limb activity. Electromyography was used to evaluate muscle activity of the gluteus maximus, tensor fascia lata, quadriceps femoris, and hamstring muscles in synchronization with the Vicon motion capture system. A HAL® session included a knee extension session with the hip flexor and voluntary gait with upper limb activity. After using the HAL® for one month, the patient’s manual muscle hip flexor scores improved from 1/5 to 2/5 for the right and from 2/5 to 3/5 for the left knee, and from 0/5 to 1/5 for the extension of both knees.

Conclusion/clinical relevance: Knee extension sessions with HAL®, and hip flexor and upper-limb-triggered HAL® ambulation seem a safe and feasible option in a patient with complete paraplegia due to spinal cord injury.  相似文献   

2.
OBJECTIVE: It is well documented that cardiopulmonary bypass (CPB) severely impairs cellular immunity. The objective of this study was to investigate the effect of prostaglandin E1 (PGE1) on cellular immunity after CPB. METHODS: Patients who underwent elective cardiac surgery were randomly divided into the PGE1 group (n=12) and the control group (n=12). In the PGE1 group, PGE1 was administered at 20 ng/kg/min from just after the induction of anesthesia to the end of surgery. Peripheral blood mononuclear cells (PBMCs) were taken before anesthesia and on postoperative days 1, 3 and 7 (POD 1, POD 3 and POD 7). Proliferation responses of T cells to phytohemagglutinin (PHA) and pure protein derivative (PPD) antigen were measured as indicators of cellular immunity. RESULTS: PGE1 significantly attenuated the impairment of both PHA and PPD response after cardiac surgery on POD 1 (PHA response, 30 +/- 21% vs. 53 +/- 32%, control vs. PGE, p=0.048; PPD response, 18 +/- 21% vs. 39 +/- 27%, control vs. PGE, p=0.046). The reduced glutathione content of PBMCs in the control group was significantly decreased on POD 1. CONCLUSION: PGE1 attenuated the impairment of cellular immunity after cardiac surgery with CPB by reducing oxidative stress on PBMCs.  相似文献   
3.
4.
A 30-year-old woman was admitted to Mie University Hospital for recurrence of sudden visual field defect with photopsia in the right eye. She had experienced the same episodes at the age of 15, 20, 25 and 28 years old. A diagnosis of retrobulbar optic neuritis had been made at each episode, but corticosteroid therapy failed to resolve the symptoms. Neurologic examination on admission was unremarkable except for the visual field defect of the right eye. Brain MRIs with and without gadolinium enhancement were normal. On ophthalmologic examination, visual acuity was normal, but the Mariotte blind spot of the right eye was expanded. Ophthalmoscopic examination, visual evoked potential, flicker electro-oculogram and Hess test were normal. Multifocal electroretinogram (ERG) revealed reduction in the inferior temporal response of the right eye that corresponded to the expansion of the Mariotte blind spot These findings were consistent with conditions of acute zonal occult outer retinopathy (AZOOR). The visual symptoms of AZOOR thus resemble those of retrobulbar optic neuritis and findings of multifocal ERG were useful to differentiate them. AZOOR is a newly established condition, and it is necessary to pay more attention to AZOOR on the differential diagnoses of acute-onset mono ocular visual disturbances.  相似文献   
5.
Benign schwannoma of the pancreas   总被引:2,自引:0,他引:2  
Reported cases of intrapancreatic schwannomas have recently increased in the literature. However, none of these cases were diagnosed clearly as schwannoma preoperatively. We herein describe the clinicopathologic findings of a solitary benign schwannoma occurring in the head of the pancreas. Additionally, the differential diagnosis versus other cystic- and solid-appearing pancreatic masses is briefly discussed.  相似文献   
6.
7.
Abstract:   A 66-year-old man was referred to our hospital with chest discomfort and shortness of breath. Seven months previously he had undergone a laparoscopic left nephroureterectomy for a left renal pelvic tumor and was given two cycles of adjuvant chemotherapy (methotrexate, epirubicin and cisplatin). Echocardiogram showed an 8-mm sized mass extending from the right atrium into the right ventricle. On computed tomography, multiple lung tumors, as well as the right atrial and ventricular mass, were seen. The patient died of acute heart failure caused by right ventricular outflow obstruction. On autopsy, a right atrial and ventricular metastasis of the initial transitional cell carcinoma was found. The patient's cause of death was acute heart failure as a result of cardiac metastasis of his initial renal pelvic carcinoma.  相似文献   
8.
When the neural tube of avian embryos is separated from the notochord and floor plate, motoneurons in the spinal cord fail to develop. In order to investigate the factors involved in this phenomenon, cell proliferation activity and cell death were observed following paramedian incision of the neural tube at the level of the segmental plate using colchicine, BrdU, and TUNEL methods. If the notochord and/or floor plate produces a substance(s) that promotes cell division in the basal plate neuroepithelium or that supports the survival of the motoneuron's neuroblasts, mitotic figures should not be present in the neuroepithelium nor should substantial cell death be observed in the ventral aspect of the notochord- and floor plate-deprived neural tube. Surprisingly, however, neither result was observed in the present experiments, with the exception of a considerable amount of homogeneously distributed cell death. Neuroepithelial cells continued to proliferate and gave rise to neuroblasts. Nevertheless, motoneurons failed to develop, and the neural tube was enveloped by only the basement membrane of the alar plate (S. Hirano and H. Tanaka, 1994,Dev. Growth Differ.36, 481–488). These morphological results revealed that the cause of the development of the anterior horn lacking a neural tube in the notochord- and neural tube-eliminated embryos is not the elimination of the source of the surviving factor(s) of the motoneuron's neuroblasts, but rather the elimination of the signals to induce the motoneurons, derived from the notochord and/or floor plate. The larger amount of cell death in the neural tube on the experimental side suggests that a nonspecific survival factor(s), necessary for the survival of a variety of types of neuroblasts, is also produced by the notochord and/or floor plate.  相似文献   
9.
During the last 5 years, 5 cases of traumatic diaphragmatic rupture were surgically treated. These cases were reported and the literature concerning traumatic diaphragmatic hernia in the last one decade in Japan, including 80 cases was studied. The purpose of this study is to discuss the most important early diagnostic tools and to consider the choice of incision and approach. The following two results were gotten. (1) Plain chest X-ray, computed tomography and ultrasonography were the most valuable diagnostic tools. (2) The choice of incision and approach depends on the stage at which the rupture is recognized (early or late), the site of rupture and associate injuries.  相似文献   
10.
OBJECTIVES: Graft failure has been reported when the arterial conduit, such as the internal thoracic artery (ITA) or the right gastroepiploic artery (GEA), is grafted to a lower grade coronary artery stenosis. The shear stress as a significant factor affecting graft patency was compared between the arterial conduit and the saphenous vein graft (SVG) after surgery. METHODS: In 101 patients, 40 ITAs, 27 GEAs and 34 SVGs were examined using a Doppler-tipped guide wire during postoperative angiography. The graft flow volume and shear stress were calculated from velocity and diameter data. The study grafts were classified according to the grade of native coronary artery stenosis: group L had more than 50 up to 75% stenosis, and group H had more than 75% stenosis. Group H consisted of 25 ITAs, 17 GEAs and 21 SVGs, while group L consisted of 15 ITAs, 10 GEAs and 13 SVGs. RESULTS: In group H, graft flow volume did not significantly differ among the ITA (34+/-11 ml/min), GEA (36+/-16 ml/min) and SVG (41+/-15 ml/min), and graft shear stress significantly (ITA vs. GEA P<0.0001; GEA vs. SVG P<0.01) differed among the ITA (16.0+/-4.8dyn/cm(2)), GEA (9.1+/-3.2dyn/cm(2)) and SVG (4.8+/-1.6dyn/cm(2)). In group L, flow volume was lower (P<0.001) in the ITA (18+/-6 ml/min) and GEA (13+/-8 ml/min) than in the SVG (35+/-16 ml/min), and shear stress was significantly (P<0.001) greater in the ITA (13.7+/-4.9dyn/cm(2)) than the GEA (5.6+/-2.0dyn/cm(2)) or SVG (4.6+/-2.0dyn/cm(2)). CONCLUSIONS: These data suggest that shear stress of the ITA is superior and maintained despite the flow volume being reduced by flow competition. Lower shear stress of the GEA for intermediate stenosis may be associated with the development of conduit failure.  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