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   43426篇
  免费   2075篇
  国内免费   325篇
耳鼻咽喉   315篇
儿科学   761篇
妇产科学   521篇
基础医学   5695篇
口腔科学   1153篇
临床医学   2610篇
内科学   10785篇
皮肤病学   978篇
神经病学   2802篇
特种医学   1619篇
外科学   8162篇
综合类   193篇
一般理论   1篇
预防医学   1275篇
眼科学   728篇
药学   2474篇
中国医学   139篇
肿瘤学   5615篇
  2023年   243篇
  2022年   600篇
  2021年   989篇
  2020年   511篇
  2019年   723篇
  2018年   942篇
  2017年   762篇
  2016年   884篇
  2015年   919篇
  2014年   1228篇
  2013年   1535篇
  2012年   2506篇
  2011年   2921篇
  2010年   1656篇
  2009年   1359篇
  2008年   2535篇
  2007年   2825篇
  2006年   2621篇
  2005年   2811篇
  2004年   2732篇
  2003年   2706篇
  2002年   2692篇
  2001年   692篇
  2000年   635篇
  1999年   733篇
  1998年   691篇
  1997年   535篇
  1996年   517篇
  1995年   434篇
  1994年   361篇
  1993年   363篇
  1992年   413篇
  1991年   355篇
  1990年   350篇
  1989年   329篇
  1988年   289篇
  1987年   261篇
  1986年   239篇
  1985年   236篇
  1984年   205篇
  1983年   174篇
  1982年   113篇
  1981年   109篇
  1980年   110篇
  1979年   134篇
  1978年   96篇
  1977年   72篇
  1975年   60篇
  1974年   61篇
  1973年   69篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
101.
Patterns of Age-Related Immunologic Changes   总被引:1,自引:0,他引:1  
  相似文献   
102.
Summary: In situ hybridization of mRNA for collagen IV, collagen VI, stromelysin (MMP-3) and TIMP1 was examined in renal biopsy specimens from patients with IgA nephropathy (IgAN) or diabetic nephropathy with various degrees of tissue damage. The majority of cells in the glomeruli expressed these mRNA almost simultaneously, but a few cells demonstrated positive expression for only one of these probes. There was a parallel relationship between the degree of tissue damage and that of mRNA expressions of these probes in patients with IgAN, while patients with diabetic nephropathy showed a reverse relationship between these two parameters. It is concluded that patients with mesangial proliferative glomerulonephritis expressed mRNA for collagen collagenase and its inhibitor in the glomeruli in parallel with the progress of tissue damage. In contrast, glomerular samples from patients with diabetic nephropathy showed that there was an inverse relationship between tissue damage and expression of mRNA. It is concluded that expression of collagen, collagenase and its inhibitor parallels the progression of glomerular changes in IgAN, but such parallel expression was not observed in patients with diabetic nephropathy.  相似文献   
103.
We report the surgical results of 13 accessory nerve neurotizations in brachial plexus birth palsy. The mean age at operation was 5.9 months. The accessory nerve was transferred to three C5 roots, to three C6 roots, to four posterior division of the middle trunks, to one musculocutaneous nerve, and to two suprascapular nerves. Sixty-seven percent of the cases acquired M4 or more in the deltoid muscle, 88% in the infraspinatus muscle, and 100% in the biceps brachii muscle. Twenty-five percent of the cases acquired M4 or more in the triceps brachii muscle and the wrist extensor muscles. These results were much better than formerly reported for adult cases by other authors. No functional compromise of the trapezius muscle was noted. The accessory nerve neurotization can be used safely and effectively in neurosurgical reconstruction of the brachial plexus palsy in infants. © 1994 Wiley-Liss, Inc.  相似文献   
104.
Two elderly women complaining of intermittent claudication complicated with persistent sciatic artery are herein reported. A direct femoral arteriogram showed hypoplasty of the superficial femoral artery and an unnatural anatomical relationship between the distal superficial femoral artery and the proximal popliteal artery, thus suggesting the presence of persistent sciatic artery. The diagnosis of persistent sciatic artery was finally made based on the aortography findings including the iliac arterial system and computed tomography (CT) scan. Magnetic resonance imaging (MRI) was helpful to demonstrate the entire image of this anomaly in cases with non-thrombolized sciatic artery. These diagnostic methods were useful in designing the optimal surgical strategy. The first case with a gluteal pulsating mass underwent exclusion of the persistent sciatic artery including the aneurysm through a retroperitoneal approach with a combination of femorotibial bypass, while the second case with thrombosed persistent sciatic artery only underwent femoropopliteal bypass. To recognize such a rare lesion, awareness of the differential diagnosis is important, and to provide appropriate treatment, an accurate whole image including adequate angiography, a CT scan, and magnetic resonance imaging is necessary.  相似文献   
105.
A 74-year-old man with combined valvular disease with a recent cerebral infarction was admitted. While undergoing thorough examination for valvular disease, absent right superior vena cava (RSVC) and persistent left superior vena cava (PLSVC) were recognized. Chest X-ray film suggested a right arch protrusion, and CT and venogram confirmed the diagnosis. During surgery, replacement of the mitral and aortic valves and annuloplasty of the tricuspid valve were performed. A blood draining cannula was inserted in retrograde fashion from the coronary sinus into the PLSVC, without any difficulties in the tricuspid valve repair. Due to bradycardic atrial fibrillation, we believed that it would be difficult to insert an endocardial electrode postoperatively, hence myocardial electrode was placed in the right ventricular wall. Absent RSVC combined with PLSVC is very rare, and a patient who underwent combined valve surgery with this rare anatomical abnormality is herein presented.  相似文献   
106.
A 53-year-old man with adult T-cell leukemia (ATL) developed progressive left hemiparesis and left homonymous hemianopsia. Magnetic resonance imaging (MRI) one month later showed multiple high-intensity lesions in the white matter of both occipital lobes, with predominance in the right side. Detection of JCV genome with polymerase chain reaction in his cerebrospinal fluid subsequently confirmed the diagnosis of progressive multifocal leukoencephalopathy (PML). He was admitted to our hospital. The serum level of soluble interleukin-2 receptor in the patient increased, and both edema and new Gd-enhanced lesions were observed in the cortex of the occipital lobe. He was treated with systemic administrations of Pirarubicin. Cyclophosphamide, and Prednisolone. as well as intrathecal injection of Methotrexate and Cytarabine. Although these treatments temporarily alleviated the symptoms of PML. the ATL spread to the liver and kidney. He died of multiple organ failure. Analysis of his JCV genes revealed that there were three types of rearrangements in the regulatory domains of the JCV genes. All three types lacked the domain B. and two had duplicate domain A. This is the first report of the simultaneous detection of three different types of rearrangements in JCV genes in a single patient. It has been reported that white-matter lesions caused by typical PML are not enhanced in Gd-MRI. However. the lesions seen in this patient were enhanced in Gd-MRI. Such enhancement might be attributable to the modification of the lesions through the direct invasion of ATL cells to the central nervous system.  相似文献   
107.
Intraosseous ganglia of the glenoid are rare, and their etiology is unknown. This report describes a case of an intraosseous ganglion about to cause fracture of the glenoid. The patient was a 61-year-old woman with a painful left shoulder with a limited range of motion. Her symptoms did not improve after non-operative treatment. Arthroscopic examination showed a cartilage defect and erosion in the posteroinferior portion of the glenoid, behind which computed tomography (CT) showed a cystic lesion of the glenoid. There was no communication between the cyst and the joint space. The patient was treated by curettage and an autogenous cancellous bone graft from the iliac crest. Two years after the operation, the patient was almost free from pain, and CT showed good integration of the bone graft.  相似文献   
108.
Three-dimensional fast asymmetric spin echo (3D FASE) cisternography provides high spatial resolution and excellent contrast as a water image acquisition technique. It is also useful for the evaluation of various anatomical regions. This study investigated the usefulness and limitations of virtual endoscopic images obtained by 3D FASE MR cisternography in the preoperative evaluation of patients with neurovascular compression. The study included 12 patients with neurovascular compression: 10 with hemifacial spasm and two with trigeminal neuralgia. The diagnosis was surgically confirmed in all patients. The virtual endoscopic images obtained were judged to be of acceptable quality for interpretation in all cases. The areas of compression identified in preoperative diagnosis with virtual endoscopic images showed good agreement with those observed from surgery, except in one case in which the common trunk of the anterior inferior cerebellar artery and posterior inferior cerebellar artery (AICA-PICA) bifurcated near the root exit zone of the facial nerve. The veins are displayed in some cases but not in others. The main advantage of generating virtual endoscopic images is that such images can be used for surgical simulation, allowing the neurosurgeon to perform surgical procedures with greater confidence.  相似文献   
109.
The influence of experimentally induced hepatic dysfunction on the pharmacokinetics of Cyclosporine A (CsA) was determined in dogs. The pharmacokinetics of oral (PO) and intravenous (IV) CsA were studied before and after 70 per cent hepatectomy or complete bile duct ligation (CBDL). Changes in liver function were monitored by serial measurements of serum bilirubin, and by the maximum removal rate (Rmax) and plasma disappearance rate (ICG-K) of indocyanine green (ICG). Concentrations of CsA in whole blood were measured by HPLC. Seventy per cent hepatectomy caused significant liver dysfunction: the ICG-Rmax decreased by 47.7±7.1 per cent (mean±SD) and the ICG-K decreased by 61.3±9.7 per cent during the first week after hepatectomy. At the same time, the systemic clearance (CLs) of IV-CsA decreased by 43.9±8.2 per cent, the area under the concentration curve (AUC) of IV-CsA increased by 35.4±20.8 per cent and the bioavailability of CsA decreased by 26.4±14.8 per cent. CBDL also induced significant liver dysfunction: the ICG-Rmax decreased by 39.1±12.8 per cent and the ICG-K decreased by 65.6±3.6 per cent in the second week after the operation. During the same period, the AUC of PO-CsA decreased by 69.9±10.7 per cent and the bioavailability of CsA also decreased markedly by 73.9±15.6 per cent. These data indicate that hepatic impairment significantly influences the pharmacokinetics of CsA, not only by the changes in intestinal absorption, but also by those in hepatic, metabolism. Dose adjustment is therefore necessary in the presence of hepatic dysfunction in order to maintain an adequate blood concentration of CsA without causing side effects. This research was performed in the Department of Surgery, University of Pittsburgh Health Center, University of Pittsburgh, USA  相似文献   
110.
The present study was designed to examine the selectivity of 3H-CGP-12177 (4-(3-t-butylamino-2-hydroxypropoxy)-[5,7-3H]benzimidazole-2-one hydrochloride) for beta 1- and beta 2-adrenergic receptors by the Scatchard and the displacement analysis. The plots of specific binding obtained from the Scatchard analysis using 3H-CGP12177 for the rat myocardium membrane were uniphasic when the non-specific binding was determined by the use of 10 microM I-propranolol, and the Kd and Bmax values were 408.53 +/- 67.20 pM and 12.27 +/- 0.83 fmoles/mg protein, respectively. On the other hand, two binding sites were observed in the displacement curve when I-metoprolol was used as a competitor. The existence of these two binding sites implied the selectivity of 3H-CGP12177 to beta-adrenoceptors because 3H-CGP12177 was 1.8-fold more selective towards beta 1-adrenoceptors than beta 2-adrenoceptors. In addition, these two binding sites could be regarded as beta 1- and beta 2-adrenergic receptors from the evaluation of the binding characteristics beta-adrenoceptors by the displacement analysis using beta-selective antagonists. Thus, 3H-CGP12177, a hydrophilic radioligand, was useful for the binding assay of beta-adrenoceptors in rat myocardial membranes.  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