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   437篇
  免费   15篇
  2023年   4篇
  2022年   6篇
  2021年   18篇
  2020年   11篇
  2019年   13篇
  2018年   11篇
  2017年   9篇
  2016年   14篇
  2015年   20篇
  2014年   25篇
  2013年   31篇
  2012年   35篇
  2011年   31篇
  2010年   21篇
  2009年   24篇
  2008年   29篇
  2007年   29篇
  2006年   25篇
  2005年   11篇
  2004年   18篇
  2003年   18篇
  2002年   20篇
  2001年   2篇
  2000年   4篇
  1999年   5篇
  1998年   3篇
  1997年   1篇
  1992年   3篇
  1991年   1篇
  1988年   1篇
  1986年   1篇
  1985年   1篇
  1983年   2篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1977年   1篇
  1969年   1篇
排序方式: 共有452条查询结果,搜索用时 31 毫秒
421.

Background

Red cell distribution width (RDW), one of many routinely examined parameters, shows the heterogeneity in erythrocyte size. We investigated the association of RDW levels with clinical parameters and prognosis of lung cancer patients.

Methods

Clinical and laboratory data from 332 patients with lung cancer in a single institution were retrospectively studied by univariate analysis. Kaplan-Meier survival analysis and Cox proportional hazard models were used to examine the effect of RDW on survival.

Results

The RDW levels were divided into two groups: high RDW (>=15%), n=73 vs. low RDW, n=259 (<15%). Univariate analysis showed that there were significant associations of high RDW values with cancer stage, performance status, presence of other disease, white blood cell count, hemoglobin, mean corpuscular volume, platelet count, albumin level, C-reactive protein level, and cytokeratin 19 fragment level. Kruskal-Wallis tests revealed an association of RDW values with cancer stage in patients irrespective of comorbidity (patient with/without comorbidity: p<0.0001, patient without comorbidity: p<0.0001). Stages I-IV lung cancer patients with higher RDW values had poorer prognoses than those with lower RDW values (Wilcoxon test: p=0.002). In particular, the survival rates of stage I and II patients (n=141) were lower in the high RDW group (n=19) than in the low RDW group (n=122) (Wilcoxon test: p<0.001). Moreover, multivariate analysis showed higher RDW is a significant prognostic factor (p=0.040).

Conclusion

RDW is associated with several factors that reflect inflammation and malnutrition in lung cancer patients. Moreover, high levels of RDW are associated with poor survival. RDW might be used as a new and convenient marker to determine a patient’s general condition and to predict the mortality risk of lung cancer patients.  相似文献   
422.
Interleukin-6 (IL-6) is a pleiotropic cytokine that affects various functions, including tumor development. Although the importance of IL-6 in gastric cancer has been documented in experimental and clinical studies, the mechanism by which IL-6 promotes gastric cancer remains unclear. In this study, we investigated the role of IL-6 in the epithelial–stromal interaction in gastric tumorigenesis. Immunohistochemical analysis of human gastritis, gastric adenoma, and gastric cancer tissues revealed that IL-6 was frequently detected in the stroma. IL-6–positive cells in the stroma showed positive staining for the fibroblast marker α-smooth muscle actin, suggesting that stromal fibroblasts produce IL-6. We compared IL-6 knockout (IL-6−/−) mice with wild-type (WT) mice in a model of gastric tumorigenesis induced by the chemical carcinogen N-methyl-N-nitrosourea. The stromal fibroblasts expressed IL-6 in tumors from WT mice. Gastric tumorigenesis was attenuated in IL-6−/− mice, compared with WT mice. Impaired tumor development in IL-6−/− mice was correlated with the decreased activation of STAT3, a factor associated with gastric cancer cell proliferation. In vitro, when gastric cancer cell line was co-cultured with primary human gastric fibroblast, STAT3–related genes including COX-2 and iNOS were induced in gastric cancer cells and this response was attenuated with neutralizing anti-IL-6 receptor antibody. IL-6 production from fibroblasts was increased when fibroblasts were cultured in the presence of gastric cancer cell–conditioned media. IL-6 production from fibroblasts was suppressed by an interleukin-1 (IL-1) receptor antagonist and siRNA inhibition of IL-1α in the fibroblasts. IL-1α mRNA and protein were increased in fibroblast lysate, suggesting that cell-associated IL-1α in fibroblasts may be involved. Our results suggest the importance of IL-6 mediated stromal-epithelial cell interaction in gastric tumorigenesis.  相似文献   
423.
Plant Molecular Biology - Homologous genes for the peptidoglycan precursor flippase MurJ,&nbsp;and peptidoglycan hydrolases: lytic transglycosylase MltB, and dd-carboxypeptidase VanY are...  相似文献   
424.

Purpose

Acetylcholinesterase (AChE) inhibitors have been used for patients with Alzheimer''s disease. However, its pharmacokinetics in non-target organs other than the brain has not been clarified yet. The purpose of this study was to evaluate the relationship between the whole-body distribution of intravenously administered 11C-Donepezil (DNP) and the AChE activity in the normal rat, with special focus on the adrenal glands.

Methods

The distribution of 11C-DNP was investigated by PET/CT in 6 normal male Wistar rats (8 weeks old, body weight  = 220±8.9 g). A 30-min dynamic scan was started simultaneously with an intravenous bolus injection of 11C-DNP (45.0±10.7 MBq). The whole-body distribution of the 11C-DNP PET was evaluated based on the Vt (total distribution volume) by Logan-plot analysis. A fluorometric assay was performed to quantify the AChE activity in homogenized tissue solutions of the major organs.

Results

The PET analysis using Vt showed that the adrenal glands had the 2nd highest level of 11C-DNP in the body (following the liver) (13.33±1.08 and 19.43±1.29 ml/cm3, respectively), indicating that the distribution of 11C-DNP was the highest in the adrenal glands, except for that in the excretory organs. The AChE activity was the third highest in the adrenal glands (following the small intestine and the stomach) (24.9±1.6, 83.1±3.0, and 38.5±8.1 mU/mg, respectively), indicating high activity of AChE in the adrenal glands.

Conclusions

We demonstrated the whole-body distribution of 11C-DNP by PET and the AChE activity in the major organs by fluorometric assay in the normal rat. High accumulation of 11C-DNP was observed in the adrenal glands, which suggested the risk of enhanced cholinergic synaptic transmission by the use of AChE inhibitors.  相似文献   
425.
426.
Land use changes have generally been considered a local matter, but they are becoming an issue of much wider concern as changes in the use of non-agricultural lands occasionally generate nationwide agricultural pest problems. Plautia stali Scott is a serious pest in orchards, and the widespread distribution of this pest is likely associated with the expansion of planted coniferous forests in Japan. An experiment was conducted on 29 study sites in diverse areas of planted coniferous forest in central Japan, and the abundance of P. stali was monitored over four seasons for 3 years. Results revealed that the optimum radius required to cause an effect on the area surrounding the conifer planted forest was up to 4 km—specifically, 2,000, 400, 1,500, and 200 m in April, June, August, and October, respectively. Positive correlations were observed between conifer planted forests and the collected numbers of P. stali in April, June, and August. These temporal scales provide a direct evaluation of the landscape effects of a conifer planted forest on population dynamics, and this information will contribute to the development and improvement of area-wide P. stali management.  相似文献   
427.
Family Polycopidae is one of the more abundant and diverse taxa occurring in marine interstitial environments. Most of the interstitial polycopids are so far known from Japan and belong to the genus Parapolycope Klie, 1936. In this paper we describe another four new species from Japan. A new genus, K liecope gen. nov. is erected to include one new species K liecope mihoensis sp. nov. and one new combination Kliecope oligohalina (Tanaka & Tsukagoshi, 2010) comb. nov. Although the morphology of K liecope is similar to Parapolycope, the new genus has the following diagnostic characters: absence of an inward bulge on the antennular second podomere, presence of two setae bearing a sucker on the antennular third podomere, and absence of a dorsal seta on the basis of mandibula. Another three Parapolycope, P arapolycope setouchiensis sp. nov. , P arapolycope subtidalis sp. nov. , and P arapolycope miurensis sp. nov. are described as well. To test the phylogenetic relationship between the new genus and Parapolycope, we performed phylogenetic analyses based on the 14 18S rDNA sequences of interstitial Polycopidae species, 12 of which were newly obtained from our material. The 18S gene proved to be suitable for phylogenetic analyses in polycopids with high intraspecific or intrageneric resolution. Here we present trees obtained with maximum likelihood, maximum parsimony, and neighbour‐joining methods, and they support the divergence between Kliecope and Parapolycope with high bootstrap values. © 2014 The Linnean Society of London  相似文献   
428.
The stratum intermedium develops as flattened cell layers on the proximal side of the ameloblast layer during tooth development. However, little information is available regarding the origin and the role. In this study, we indicate that some stratum intermedium cells originate from the inner enamel epithelium (IEE) in rat incisor organ cultures using DiI as a tracer. Immunohistochemical and in situ hybridization studies showed that the stratum intermedium cells express the Notch1 protein and Hes1 mRNAs, while the IEE and ameloblasts express the Jagged1. Further, we examined the role of Notch signaling using the dental epithelial cell line HAT-7. Recombinant Jagged1 protein enhanced the appearance of stratum intermedium cells in HAT-7 cultures and neutralization with an anti-Jagged1 antibody inhibited these effects. Additionally, overexpression of the Notch1 internal domain increased the number of stratum intermedium cells. We hypothesize that the stratum intermedium lineage differentiates from the ameloblast lineage via Notch signaling.  相似文献   
429.
430.
We investigated the location and distribution of paramagnetic species in dry black, brown, and yellow (normal) soybean seeds using electron paramagnetic resonance (EPR), X-band (9?GHz) EPR imaging (EPRI), and HPLC. EPR primarily detected two paramagnetic species in black soybean. These two different radical species were assigned as stable organic radical and Mn2+?species based on the g values and hyperfine structures. The signal from the stable radical was noted at g?≈?2.00 and was relatively strong and stable. Subsequent noninvasive two-dimensional (2D) EPRI of the radical present in black soybean revealed that the stable radical was primarily located in the pigmented region of the soybean coat, with very few radicals observed in the soybean cotyledon (interior). Pigments extracted from black soybean were analyzed using HPLC. The major compound was found to be cyanidin-3-glucoside. Multi-EPR and HPLC results indicate that the stable radical was only found within the pigmented region of the soybean coat, and it could be cyanidin-3-glucoside or an oxidative decomposition product.  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