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   605篇
  免费   23篇
  2020年   1篇
  2019年   2篇
  2018年   5篇
  2017年   5篇
  2016年   5篇
  2015年   11篇
  2014年   13篇
  2013年   59篇
  2012年   25篇
  2011年   35篇
  2010年   19篇
  2009年   16篇
  2008年   39篇
  2007年   39篇
  2006年   37篇
  2005年   45篇
  2004年   56篇
  2003年   32篇
  2002年   55篇
  2001年   7篇
  2000年   4篇
  1999年   6篇
  1998年   7篇
  1997年   5篇
  1996年   6篇
  1995年   9篇
  1994年   9篇
  1993年   4篇
  1992年   4篇
  1991年   6篇
  1990年   5篇
  1989年   2篇
  1988年   6篇
  1987年   3篇
  1986年   4篇
  1985年   6篇
  1984年   4篇
  1983年   5篇
  1982年   7篇
  1981年   4篇
  1980年   4篇
  1978年   2篇
  1977年   3篇
  1976年   1篇
  1974年   3篇
  1973年   2篇
  1972年   1篇
排序方式: 共有628条查询结果,搜索用时 640 毫秒
101.
We describe a case of inflammatory myofibroblastic tumor (IMT) that occurred in the retroperitoneum. The patient manifested systemic symptoms, such as intermittent fever, anemia, thrombocytosis, and hypergammaglobulinemia. In order to elucidate the mechanism of intermittent fever in IMT, we analyzed nuclear factor-kappa B (NF-kappaB) activation in peripheral blood mononuclear cells (PBMCs) using flow cytometry, and serum cytokine levels. NF-kappaB activation was observed in the peripheral blood T cells and monocytes/macrophages. Among the measured cytokines, only interleukin (IL)-6 levels were elevated. IL-6 levels during pyrexia in the afternoon were higher than those during apyrexia in the morning. In contrast to IL-6, NF-kappaB activation in PBMCs was lower during pyrexia than during apyrexia; this is considered to be because the activation is subject to negative feedback. The time lag between the increase of IL-6 in the serum and NF-kappaB activation in the PBMCs at the onset of intermittent fever in IMT may provide further insight into the role of cytokines and NF-kappaB activation in febrile inflammatory diseases.  相似文献   
102.
Aim: Inorganic polyphosphate exists as chains of phosphate molecules and is distributed in osteoblasts, and regulates osteoblastic cell differentiation and bone matrix calcification. The purpose of this study was to clarify the effects of inorganic polyphosphate on periodontitis. Material and methods: Subgingival local irrigation with inorganic polyphosphate was studied in a randomised double‐blind study of 33 patients with periodontitis. Scaling and root planing were performed 1 week after the initial examination. Results: No significant differences between the inorganic polyphosphate group and control were detected in each item except IL‐1β. Patients in whom both the bleeding on probing and gingival index at 1 week had improved were significantly older in the inorganic polyphosphate group than in the control group (p < 0.05). Bone regeneration was seen in one case of the inorganic polyphosphate group. Conclusions: Inorganic polyphosphate was useful in the treatment of periodontitis in the elderly, indicating a probable effect of anti‐ageing, with similar bone regenerations occurring in both groups.  相似文献   
103.
We investigated changes in the sub-cellular distribution of glycelaldehyde-3-phosphate dehydrogenase (GAPDH) after X-ray irradiation in HeLa cells. Twenty-four h after irradiation at 5 Gy, nuclear GAPDH levels increased 2.6-fold, whereas total GAPDH levels increased only 1.2-fold. Knockdown of GAPDH using specific small interfering RNA (siRNA) led to sensitization to X-ray-induced cell death. These results suggest that GAPDH plays a role in the radioresponse.  相似文献   
104.
The Awajishima Monkey Center (AMC) free-ranging, provisioned population of Japanese macaques has included individuals with congenital limb malformations (CLMs) for at least 40 years. Including new data from this study, 16.1% of AMC infants from 1969 to 2007 (185 of 1,150) were born with CLMs. However, relatively little is known about the demographics of CLMs in the population, particularly the relationships among occurrence and severity of CLMs and age-sex demographics after infancy. In 2004, we conducted a census at AMC. Of the 199 monkeys censused, 34 individuals (17.1%) had CLMs. To estimate the severity of CLMs, we created an index that ranks individuals on a scale of 0 to 1 based on affected and absent limbs and digits. The severity of CLMs varied greatly (index range = 0.01-0.79, mean = 0.29), with similar variation in severity in each age-sex class (Student t-test, P > 0.05).  相似文献   
105.
We designed and synthesized alkylating conjugates 57 and their partner N-methylpyrrole-N-methylimidazole (PI) polyamides 8, 9. The DNA alkylating activities of conjugates 57 were evaluated by high-resolution denaturing polyacrylamide gel electrophoresis with a 219 base pair (bp) DNA fragment containing the human telomere repeat sequence. Conjugate 5 efficiently alkylated the sequence, 5′-GGTTAGGGTTA-3′, in the presence of partner PI polyamide 8 or distamycin A (Dist). In contrast, the heterodimer system of 5 with 9 showed very weak alkylating activity. Accordingly, this heterotrimeric system of 5 with two short partners is an expedient way to attain improved precision and extension of the recognition of DNA sequences.  相似文献   
106.
The preprotachykinin C gene encodes four endokinins, A, B, C, and D. Endokinins A and B and substance P (SP) are typical tachykinin peptides since their carboxyl-terminal regions share an F-F-G-L-M-amide, while endokinins C and D share an F-Q-G-L-L-amide. It is demonstrated that pretreatment with a peptide consisting of a common sequence between endokinins C and D (EKC/D) attenuates the induction of scratching behavior and thermal hyperalgesia by intrathecal administration of SP or EKA/B (the carboxyl-terminal dacapeptide common in endokinins A and B), suggesting that leucine at the carboxyl-terminal of EKC/D may have a crucial role in eliciting these effects. When the effect of [Leu11]-SP and [Leu10]-EKA/B on SP-induced pain-related behavior was examined, the induction of pain-related behavior was markedly attenuated by pretreatment with these peptides. This indicates that leucine at the carboxyl-terminal of these peptides plays a crucial role in eliciting this antagonistic effect.  相似文献   
107.
108.
Question: How do traditional management practices of field margins maintain the biodiversity of native grassland species? Location: Semi‐natural grassland on the field margins of traditional and consolidated agricultural fields on Awaji Island, central Japan. Methods: The distance to the nearest traditional field margin to the study sites was determined because the traditional field was considered as a seed source of native vegetation to the semi‐natural grasslands under study. We selected field margins in consolidated fields of different ages and distances from seed sources. Indicator species for both field types were sought. Regression analysis and detrended correspondence analysis (DCA) were used to determine the effect of spatial and temporal distances on the species composition of native vegetation. Results: Species richness differed significantly between the margin of traditional and consolidated fields. We identified significant indicator species of traditional fields, but not of consolidated fields. In consolidated fields, species richness increased significantly with age and decreased significantly with increasing distance to the source. At younger sites, species richness decreased faster with distance to the source because of strong negative correlation, but not at older sites. DCA ordination plots similarly indicated that similarities of vegetation composition in consolidated and traditional fields decreased with distance, and the effect of distance decreased with age. Conclusions: The species composition of the grassland margins of consolidated field was more similar to the margins of traditional fields if the consolidated fields were older, and/or closer to traditional fields. This pattern suggests that dispersal may play a role in the establishment of species on field margins.  相似文献   
109.
We have characterized the structural and molecular interactions of CC-chemokine receptor 5 (CCR5) with three CCR5 inhibitors active against R5 human immunodeficiency virus type 1 (HIV-1) including the potent in vitro and in vivo CCR5 inhibitor aplaviroc (AVC). The data obtained with saturation binding assays and structural analyses delineated the key interactions responsible for the binding of CCR5 inhibitors with CCR5 and illustrated that their binding site is located in a predominantly lipophilic pocket in the interface of extracellular loops and within the upper transmembrane (TM) domain of CCR5. Mutations in the CCR5 binding sites of AVC decreased gp120 binding to CCR5 and the susceptibility to HIV-1 infection, although mutations in TM4 and TM5 that also decreased gp120 binding and HIV-1 infectivity had less effects on the binding of CC-chemokines, suggesting that CCR5 inhibition targeting appropriate regions might render the inhibition highly HIV-1-specific while preserving the CC chemokine-CCR5 interactions. The present data delineating residue by residue interactions of CCR5 with CCR5 inhibitors should not only help design more potent and more HIV-1-specific CCR5 inhibitors, but also give new insights into the dynamics of CC-chemokine-CCR5 interactions and the mechanisms of CCR5 involvement in the process of cellular entry of HIV-1.  相似文献   
110.
The Toxicogenomics Project is a 5-year collaborative project by the Japanese government and pharmaceutical companies in 2002. Its aim is to construct a large-scale toxicology database of 150 compounds orally administered to rats. The test consists of a single administration test (3, 6, 9 and 24 h) and a repeated administration test (3, 7, 14 and 28 days), and the conventional toxicology data together with the gene expression data in liver as analyzed by using Affymetrix GeneChip are being accumulated. In the project, either methylcellulose or corn oil is employed as vehicle. We examined whether the vehicle itself affects the analysis of gene expression and found that corn oil alone affected the food consumption and biochemical parameters mainly related to lipid metabolism, and this accompanied typical changes in the gene expression. Most of the genes modulated by corn oil were related to cholesterol or fatty acid metabolism (e.g., CYP7A1, CYP8B1, 3-hydroxy-3-methylglutaryl-Coenzyme A reductase, squalene epoxidase, angiopoietin-like protein 4, fatty acid synthase, fatty acid binding proteins), suggesting that the response was physiologic to the oil intake. Many of the lipid-related genes showed circadian rhythm within a day, but the expression pattern of general clock genes (e.g., period 2, arylhydrocarbon nuclear receptor translocator-like, D site albumin promoter binding protein) were unaffected by corn oil, suggesting that the effects are specific for lipid metabolism. These results would be useful for usage of the database especially when drugs with different vehicle control are compared.  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