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   3435篇
  免费   90篇
  国内免费   40篇
耳鼻咽喉   13篇
儿科学   32篇
妇产科学   27篇
基础医学   447篇
口腔科学   68篇
临床医学   143篇
内科学   1010篇
皮肤病学   33篇
神经病学   289篇
特种医学   156篇
外科学   540篇
综合类   8篇
预防医学   83篇
眼科学   43篇
药学   179篇
中国医学   8篇
肿瘤学   486篇
  2022年   24篇
  2021年   38篇
  2020年   28篇
  2019年   34篇
  2018年   32篇
  2017年   30篇
  2016年   53篇
  2015年   49篇
  2014年   85篇
  2013年   95篇
  2012年   154篇
  2011年   210篇
  2010年   108篇
  2009年   96篇
  2008年   172篇
  2007年   212篇
  2006年   204篇
  2005年   229篇
  2004年   235篇
  2003年   210篇
  2002年   226篇
  2001年   90篇
  2000年   75篇
  1999年   81篇
  1998年   59篇
  1997年   57篇
  1996年   50篇
  1995年   44篇
  1994年   42篇
  1993年   44篇
  1992年   49篇
  1991年   44篇
  1990年   40篇
  1989年   44篇
  1988年   26篇
  1987年   27篇
  1986年   19篇
  1985年   16篇
  1984年   18篇
  1983年   18篇
  1981年   16篇
  1980年   13篇
  1979年   14篇
  1978年   18篇
  1977年   15篇
  1976年   10篇
  1974年   17篇
  1973年   11篇
  1972年   15篇
  1970年   9篇
排序方式: 共有3565条查询结果,搜索用时 15 毫秒
101.
Cardiac ankyrin repeat protein (CARP), which is structurally characterized by the presence of four ankyrin repeat motifs in its central region, is believed to be localized in the nucleus and to participate in the regulation of cardiac-specific gene expression in cardiomyocytes. However, we recently found that CARP was induced in skeletal muscle by denervation, leading us to speculate that CARP may be induced under some pathological conditions. In the present study, we immunohistochemically analyzed the expression of CARP in 11 cases of spinal muscular atrophy (SMA) and 14 cases of congenital myopathy. In SMA, CARP was expressed selectively in severely atrophic myofibers, suggesting that CARP expression may reflect the status of muscle atrophy. Furthermore, in the congenital myopathies, the expression patterns of CARP were distinct among the subtypes, which included nemaline myopathy, myotubular myopathy, central core disease, and congenital fiber type disproportion. Although CARP was preferentially expressed in severely damaged myofibers in nemaline myopathy, it was not detected in central core disease. These findings suggest that immunohistochemical evaluation of CARP may be helpful in the diagnosis of SMA and the congenital myopathies.  相似文献   
102.
Amino acid transport systems play an important role in cellular proliferation. L-type amino acid transporter 1 (LAT1) has been associated with tumor growth, and is highly expressed in the established tumor cell lines and primary human neoplasms. In this study, we investigated the expression of LAT1 to evaluate the malignant potential and prognostic significance in neuroendocrine (NE) tumors of the lung. Twenty-one surgically resected, large cell neuroendocrine carcinomas (LCNEC), 13 small cell lung cancers (SCLC), five atypical carcinoids (AC), and 10 typical carcinoids (TC) were enrolled in the study. LAT1 expression and Ki-67 labeling index of the NE tumors were analyzed by immunohistochemical staining. LAT1 was overexpressed in 52.4% of the LCNEC, in 46.2% of the SCLC, and in 25% of the AC. LAT1 expression in LCNEC was significantly associated with lymph node metastasis and poor outcome. Moreover, a significant correlation was found between LAT1 expression and Ki-67 in both LCNEC and SCLC. Expression of LAT1 tended to increase from low-grade to high-grade NE tumors. The present results suggest that LAT1 may play a significant role in cellular proliferation, lymph node metastasis, and poor outcome in patients with NE tumors of the lung.  相似文献   
103.
A subset of human peripheral blood mononuclear cells (PB-MNCs) differentiate into endothelial progenitor cells (EPCs) that participate in postnatal neovascularization. Although tissue ischemia can mobilize EPCs from bone marrow, the effects of hypoxia on differentiation and angiogenic function of EPCs are little known. We examined whether hypoxic conditioning would modulate differentiation and function of human PB-MNC-derived EPCs. A subset of PB-MNCs gave rise to EPC-like attaching (AT) cells under either normoxic or hypoxic conditions. However, hypoxia much enhanced the differentiation of AT cells from PB-MNCs compared with normoxia. AT cells released vascular endothelial growth factor (VEGF) protein and expressed CD31 and kinase insert domain receptor/VEGFR-2, endothelial lineage markers, on their surface, which were also enhanced by hypoxia. Both a neutralizing anti-VEGF mAb and a KDR-specific receptor tyrosine kinase inhibitor, SU1498, suppressed PB-MNC differentiation into EPC-like AT cells in a dose-dependent manner. Migration of AT cells in response to VEGF as examined by a modified Boyden chamber apparatus was also enhanced by hypoxia. Finally, in vivo neovascularization efficacy was significantly enhanced by in vitro hypoxic conditioning of AT cells when cells were transplanted into the ischemic hindlimb of immunodeficient nude rats. In conclusion, hypoxia directly stimulated differentiation of EPC-like AT cells from human PB-MNC culture. Moreover, hypoxic preconditioning of AT cells before in vivo transplantation is a useful means to enhance therapeutic vasculogenesis.  相似文献   
104.
Parasitology Research - Blastocystis sp. is a common intestinal protist found worldwide in a variety of animals, including humans. Currently, 17 subtypes (STs) of Blastocystis isolates from...  相似文献   
105.
In intact adult mammalian brains, there are two neurogenic regions: the subependymal zone and the subgranular layer of the hippocampus. Even outside these regions, small numbers of proliferating precursors do exist. Many studies suggest that the majority of these are oligodendrocyte precursors that express NG2, a chondroitin sulfate proteoglycan, and most of the residual proliferating cells seem to be endothelial cells. However, it is still unclear whether NG2-immunonegative proliferating precursors are present, because previous studies have neglected their possible existence. In this study, we systematically analyzed the phenotypes of the proliferating cells in the intact adult rat cortical gray matter. We improved our techniques and carefully characterized the proliferating cells, because there were several problems with identifying and quantifying the proliferating cells: the detection of NG2-expressing cells was dependent on the fixation condition; there were residual proliferating leukocytes in the blood vessels; and two anti-NG2 antibodies gave rise to different staining patterns. Moreover, we used two methods, BrdU and Ki67 immunostaining, to quantify the proliferating cells. Our results strongly suggest that in the intact adult cerebral cortical gray matter, there were only two types of proliferating cells: the majority were NG2-expressing cells, including pericytes, and the rest were endothelial cells.  相似文献   
106.
Cohesin-mediated sister chromatid cohesion is established during the S-phase, and recent studies demonstrate that a cohesin protein ring concatenates sister DNA molecules. However, little is known about how DNA replication is linked to the establishment of sister chromatid cohesion. Here, we used Xenopus egg extracts to show that AND-1 and Tim1–Tipin, homologues of Saccharomyces cerevisiae Ctf4 and Tof1–Csm3, respectively, are associated with the replisome and are required for proper establishment of the cohesion observed in the M-phase extracts. Immunodepletion of both AND-1 and Tim1–Tipin from the extracts leads to aberrant sister chromatid cohesion, which is similarly induced by the depletion of cohesin. These results demonstrate that AND-1 and Tim1–Tipin are key factors linking DNA replication and establishment of sister chromatid cohesion. On the basis of the physical interactions between AND-1 and DNA polymerases, we discuss a model to describe how replisome progression complex establishes sister chromatid cohesion.  相似文献   
107.
High‐risk neuroblastoma has a poor prognosis despite multimodal treatment including high‐dose chemotherapy. A 7‐year‐old male with neuroblastoma received ex vivo‐expanded donor CD4+ T lymphocyte infusion (CD4+ DLI) after recurrence in the bone marrow following allogeneic hematopoietic stem cell transplantation from his HLA‐identical mother. The disease transiently responded to CD4+ DLI with reduction of tumor cells and a decrease of serum neuron‐specific enolase. The response was associated with development of continued high fever and an increase of cytotoxic T lymphocytes in peripheral blood. This case suggests a possibility of a graft‐versus‐tumor effect against neuroblastoma. Pediatr Blood Cancer 2009;52:895–897. © 2009 Wiley‐Liss, Inc.  相似文献   
108.
认知是脑的高级功能,其产生机制是脑科学的研究前沿之一。脑的认知功能涉及大脑皮质和皮质下的广泛脑区,不同部位涉及不同的认知类型。杏仁体(amygdala)是参与情绪性学习认知的重要结构。作者工作过的日本富山医科药科大学(现为富山大学医学部)研究生院系统情绪科学研究室长期从事杏仁体的认知功能研究,成绩卓著。本文综述了该研究室对猴脑杏仁体社会认知功能以及相关的最新研究成果,以飨读者。  相似文献   
109.
We defined mixed-dust pneumoconiosis (MDP) pathologically as a pneumoconiosis showing dust macules or mixed-dust fibrotic nodules (MDF), with or without silicotic nodules (SN), in an individual with a history of exposure to mixed dust. We defined the latter arbitrarily as a mixture of crystalline silica and nonfibrous silicates. According to our definition of MDP, therefore, MDF should outnumber SN in the lung to make a pathologic diagnosis of MDP. In the absence of confirmation of exposure, mineralogic analyses can be used to support the pathologic diagnosis. The clinical diagnosis of MDP requires the exclusion of other well-defined pneumoconioses, including asbestosis, coal workers’ pneumoconiosis, silicosis, hematite miners’ pneumoconiosis, welders’ pneumoconiosis, berylliosis, hard metal disease, silicate pneumoconiosis, diatomaceous earth pneumoconiosis, carborundum pneumoconiosis, and corundum pneumoconiosis. Typical occupations associated with the diagnosis of MDP include metal miners, quarry workers, foundry workers, pottery and ceramics workers, and stonemasons. Irregular opacities are the major radiographic findings in MDP (ILO 1980), in contrast to silicosis, in which small rounded opacities predominate. Clinical symptoms of MDP are nonspecific. MDP must be distinguished from a variety of nonoccupational interstitial pulmonary disorders.  相似文献   
110.
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