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   2661篇
  免费   94篇
  国内免费   10篇
耳鼻咽喉   17篇
儿科学   93篇
妇产科学   9篇
基础医学   352篇
口腔科学   53篇
临床医学   153篇
内科学   782篇
皮肤病学   24篇
神经病学   202篇
特种医学   55篇
外科学   385篇
综合类   11篇
预防医学   29篇
眼科学   8篇
药学   250篇
中国医学   4篇
肿瘤学   338篇
  2023年   13篇
  2022年   26篇
  2021年   51篇
  2020年   15篇
  2019年   41篇
  2018年   27篇
  2017年   22篇
  2016年   35篇
  2015年   31篇
  2014年   59篇
  2013年   76篇
  2012年   115篇
  2011年   131篇
  2010年   87篇
  2009年   74篇
  2008年   159篇
  2007年   158篇
  2006年   147篇
  2005年   155篇
  2004年   176篇
  2003年   174篇
  2002年   183篇
  2001年   46篇
  2000年   31篇
  1999年   45篇
  1998年   61篇
  1997年   36篇
  1996年   47篇
  1995年   22篇
  1994年   59篇
  1993年   56篇
  1992年   45篇
  1991年   33篇
  1990年   30篇
  1989年   24篇
  1988年   32篇
  1987年   24篇
  1986年   38篇
  1985年   15篇
  1984年   15篇
  1983年   12篇
  1982年   22篇
  1981年   16篇
  1980年   22篇
  1979年   15篇
  1977年   15篇
  1976年   9篇
  1975年   5篇
  1974年   7篇
  1969年   4篇
排序方式: 共有2765条查询结果,搜索用时 15 毫秒
61.
Polysomnographic findings and clinical symptoms were investigated in 14 cases of upper airway resistance syndrome. The mean scores of the Epworth sleepiness scale and self-rating depression scale in eight cases were 13.5 and 38.6, respectively. The mean sleep latency of the multiple sleep latency test in four cases was 10.2 min. Seven cases were treated with continuous positive airway pressure (CPAP), and one with hormone replacement therapy. The most common symptom was daytime sleepiness. Five cases had hypertension. CPAP reduced increasing negative esophageal pressure (Pes) and frequency of EEG arousals, and improved hypertension in one case. Hormone replacement therapy ameliorated increasing negative Pes and clinical symptoms.  相似文献   
62.
A 24 years old male case who died of suicide in a peak of Impetigo herpetiformis was reported. Initially he developed skin eruptions at the age of 6 years. During the last twenty-three months, skin eruptions relapsed sixteen times. Intensive therapy of adreno-cortical hormone, sex hormone and antibiotics were given. Pathological findings of endocrine and genital organs were considered to be caused by the intensive hormone therapy, No etiological finding was found in internal organs pathologically. Staphylococci aureus and epidermis were found only once in blood, twice in the pustules. However, secondary infection could not be ruled out. This case indicated that I.h. was a disease of only skin.  相似文献   
63.
Iron is an important element for life; however, intracellular labile iron overload can lead to the generation of reactive oxygen species and cellular damage. Although iron is mainly utilized for heme synthesis and is incorporated into hemoglobin, body iron status is often implicated in the pathogenesis of cardiovascular diseases. In a cell, iron is used for basic processes such as cell growth, maintenance, and repair. Thus, iron is considered to be involved in the pathogenesis of arteriosclerosis. In fact, clinical and experimental studies have shown an association between iron and arteriosclerosis. These data suggest the crosstalk between iron and arteriosclerosis. However, iron metabolism in arteriosclerosis is often complicated, and the systemic and cellular mechanisms of iron homeostasis in arteriosclerosis remain completely unsolved. Thus, in this review, we aimed to examine the role of iron in arteriosclerosis.  相似文献   
64.
Twenty-six patients who underwent pyloruspreserving pancreaticoduodenectomy (PPPD) for ductal cancer of the head of the pancreas between 1983 and 1993 were reviewed. Gastrointestinal continuity was restored by the methods of Imanaga (n=21) and Traverso (n=5). Combined resection of the portal vein and/or superior mesenteric vein was performed in 13 patients. Surgical complications occurred in 5 patients, but there were no postoperative deaths. Delayed gastric emptying was observed in 42% of patients. The median survival time for all 26 patients was 13 months. Three patients survived for more than 3 years, and one of them is currently alive without recurrence at 10 years. Differences in survival rates were not apparent between patients who underwent PPPD with and without portal vein resection. Survival rate after PPPD was compared with that after pancreaticoduodenectomy (PD) performed between 1974 and 1992; the difference was not significant. Patients who underwent noncurative PPPD had a significantly better survival rate than those who underwent noncurative PD (P<0.05). PPPD has improved the quality of life of the resected patients, without reducing survival rate. At present, PPPD by the Imanaga procedure could be the best choice for management of cancer of the pancreatic head.  相似文献   
65.
Standardization of surgical procedure for pancreatic cancer has been recognized to be necessary and important these days. Recent studies appear to exhibit efficacy of the adjuvant chemoradiation therapy before or after pancreatic surgery. In this study, we examined the standard surgery as part of the multidisciplinary treatment for pancreatic cancer. Invasive ductal carcinoma of the pancreas was resected in 121 patients in our institution from 1992 through 2005. We stopped performing an extended lymphadenectomy with pancreatectomy in 2003, but the survival rates were not significantly different between the cases before and after 2003. We usually resect half of the nerve plexus around the superior mesenteric artery (SMA) as a standard procedure. When we achieved the microscopically curative resection (R0) even if the plexus around SMA or the portal vein was invaded, there were a few long survivors for more than five years. The R0 resection is the most important factor for prolonged survival. Pancreatectomy including removal of regional lymph nodes (D2) and half of the nerve plexus around SMA and combined resection of the infiltrated portal vein is thought to be a standard surgery from the viewpoint of decrease in morbidity and maintenance of curability.  相似文献   
66.
OBJECTIVE: Previous studies indicate that hypertrophic chondrocytes can transdifferentiate or dedifferentiate and redifferentiate into bone cells during the endochondral bone formation. Mandibular condyle in aged c-src-deficient mice has incremental line-like striations consisting of cartilaginous and non-cartilaginous layers, and the former contains intact hypertrophic chondrocytes in uneroded lacunae. The purpose of this study is to determine the phenotype changes of uneroded hypertrophic chondrocytes. DESIGN: Immunohistochemical and ultrastructural examinations of the pericellular matrix of hypertrophic chondrocytes in the upper, middle, and lower regions of the mandibular condyle were conducted in aged c-src-deficient mice, using several antibodies of cartilage/bone marker proteins. RESULTS: Co-localisation of aggrecan, type I collagen, and dentin matrix protein-1 (DMP-1) or matrix extracellular phosphoprotein (MEPE) was detected in the pericellular matrix of the middle region. Ultrastructurally, granular substances in the pericellular matrix of the middle region were the remains of upper region chondrocytes, which were mixed with thick collagen fibrils. In the lower region, the width of the pericellular matrix and the amount of collagen fibrils were increased. Versican, type I collagen, DMP-1, and MEPE were detected in the osteocyte lacunae. Additionally, DMP-1 and MEPE were detected in the pericellular matrix of uneroded hypertrophic chondrocytes located in the lower, peripheral region of the mandibular condyle in younger c-src-deficient mice, but not in the aged wild-type mice. CONCLUSIONS: These results indicate that long-term survived, uneroded hypertrophic chondrocytes, at least in a part, acquire osteocytic characteristics.  相似文献   
67.
Ligand binding to neurotransmitter and hormone receptors which couple to the Gq subclass of GTP-binding protein leads to the activation of phospholipase Cβ (PLCβ) which hydrolyses phosphatidyl-inositol 4,5-bisphosphate, yielding a pair of second messengers, diacylglycerol and inositol 1,4,5-trisphosphate (IP3). The expression of PLCβ1–4 mRNAs was comparatively examined by in situ hybridization in the mouse brain. In adults, PLCβ1 mRNA was expressed predominantly in the telencephalon, including the cerebral cortex, hippocampus, amygdala, lateral septum and olfactory bulb, with little expression in most thalamic nuclei. PLCβ2 mRNA was distributed in the white matter, suggesting its expression in non-neuronal cells, most likely oligodendrocytes. PLCβ3 mRNA was specifically expressed in cerebellar Purkinje cells. The highest levels of PLCβ4 mRNA were detected in Purkinje cells. High levels of PLCβ4 mRNA were also found in the thalamus and medial septum, whereas weak signals were detected in most telencephalic regions, thus showing an expression pattern almost reciprocal to that of PLCβ1 mRNA. During development, such characteristic regional expression of PLCβ1 and PLCβ4 were observed starting in late foetal stages, while specific expression of PLCβ2 and PLCβ3 appeared in early postnatal stages. We conclude that despite the existence of four PLCβ isoforms, only one or two of them is expressed in individual neurons and glial cells. The distinct expression of PLCβs provides a molecular basis for analysing the nature of the specific signal transduction pathway leading to the production of diacylglycerol and IP3 in distinct cell types and in different regions of the brain.  相似文献   
68.
69.
70.
Blood levels of inflammatory-related cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, are elevated in patients with alcoholic liver diseases. We investigated the effects of these cytokines and ethanol on the expression of hepatic asialoglycoprotein receptors (AGPRs) in a human hepatoblastoma cell line, HepG2. An [125I]-asialo-orosomucoid binding assay showed significant increases in surface AGPR numbers in HepG2 cells by treatment with IL-1β, IL-6, and TNF-α, to levels which were approximately 130% of the values in untreated control cells. However, the enhanced AGPR numbers induced by treatment with these cytokines were markedly suppressed, to 70%–80% of the number in the untreated cells, by treatment with ethanol. Immunological detection of AGPR with a specific antibody demonstrated that the modulation of surface AGPR numbers was correlated with the cellular expression levels of AGPR. These results suggest that, although IL-1β, IL-6, and TNF-α stimulate the synthesis of hepatic AGPR, ethanol suppresses the expression of AGPR augmented by these cytokines. This leads to an increase in serum asialo-orosomucoid levels caused by the disordered catabolism mediated by AGPR in patients with alcoholic liver disease. (Received Dec. 5, 1997; accepted May 22, 1998)  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