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   370篇
  免费   27篇
  2023年   2篇
  2022年   1篇
  2021年   8篇
  2020年   4篇
  2019年   8篇
  2018年   8篇
  2017年   7篇
  2016年   14篇
  2015年   13篇
  2014年   13篇
  2013年   20篇
  2012年   37篇
  2011年   49篇
  2010年   32篇
  2009年   20篇
  2008年   39篇
  2007年   21篇
  2006年   24篇
  2005年   13篇
  2004年   21篇
  2003年   17篇
  2002年   8篇
  2001年   2篇
  1998年   1篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1980年   1篇
  1974年   2篇
  1962年   1篇
排序方式: 共有397条查询结果,搜索用时 140 毫秒
41.

Background

The role of epidermal growth factor (EGF) and its receptor (EGFR) in the pathogenesis and progression of various malignant tumors has long been known, but there is still disagreement concerning prognostic significance of EGFR expression in clear cell renal cell carcinoma (CCRCC). The present study was designed to analyze more objectively the protein EGFR expression in CCRCC and to compare its value with EGFR gene copy number changes and clinicopathologic characteristics including patient survival.

Methods

The protein EGFR expression was analyzed immunohistochemically on 94 CCRCC, and gene copy number alterations of EGFR by FISH analysis on 41 CCRCC selected according to distinct membrane EGFR staining.

Results

Membrane EGFR expression in tumor cells was heterogeneous with respect to the proportion of positive cells and staining intensity. FISH analysis did not reveal EGFR gene amplification, while polysomy of chromosome 7 found in 41% was associated with higher EGFR membrane expression. Moreover, EGFR overexpression was associated with a higher nuclear grade, larger tumor size and shorter patient''s survival, while there was no connection with pathological stage.

Conclusion

In conclusion, the protein expression of EGFR had an impact on prognosis in patients with CCRCC, while an increased copy number of chromosome 7 could be the possible reason for EGFR protein overexpression in the absence of gene amplification.  相似文献   
42.
Reactive oxygen species are important cause of tissue injury during cerebral ischemia and reperfusion (I/R). Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) are intracellular enzymes responsible for endogenous antioxidant defense of tissues affected by I/R. The aim of this study was to examine temporal and regional changes of SOD and GSH-Px activities in animals exposed to transient focal cerebral ischemia. Male Wistar Hannover rats were subjected to the right middle cerebral artery occlusion for 2?h. The animals were sacrificed immediately, 0·5, 1, 2, 3, 6, 24, 48, 72 or 168?h after ischemic procedure. SOD and GSH-Px activities were determined spectrophotometrically in the hippocampus and parietal cortex, both unilaterally and contralaterally to the occlusion. Sham-operated animals were used as the control group. Our results indicated that transient focal cerebral ischemia causes significant changes in SOD activities in the hippocampus and parietal cortex such as in GSH-Px activities in the parietal cortex, unilaterally and contralaterally to the lesion in rats during different reperfusion periods. Statistically significant activation of GSH-Px was registered neither in the right nor in the left hippocampus of ischemic animals. Copyright ? 2012 John Wiley & Sons, Ltd.  相似文献   
43.

Background

Common complex diseases are influenced by both genetic and environmental factors. Many genetic factors overlap between various autoimmune diseases. The aim of the present study is to determine whether four genetic variants known to be risk variants for several autoimmune diseases could be associated with an increased susceptibility to type 1 diabetes mellitus.

Methods and Findings

We genotyped four genetic variants (rs2358817, rs1049550, rs6679356, rs9865818) within VTCN1, ANXA11, IL12RB2 and LPP genes respectively, in 265 T1DM family trios in Croatian population. We did not detect association of these polymorphisms with T1DM. However, quantitative transmission disequilibrium test (QTDT, orthogonal model) revealed a significant association between the age of onset of T1DM and IL12RB2 rs6679356 variant. An earlier onset of T1DM was associated with the rs6679356 minor dominant allele C (p = 0.005). The association remained significant even after the Bonferroni correction for multiple testing and permutation.

Conclusions

Variants originally associated with juvenile idiopathic arthritis (VTCN1 gene), sarcoidosis (ANXA11 gene), primary biliary cirrhosis (IL12RB2 gene) and celiac disease (LPP gene) were not associated with type 1 diabetes in our dataset. Nevertheless, association of IL12RB2 rs6679356 polymorphism with the age of T1DM onset suggests that this gene plays a role in defining the time of disease onset.  相似文献   
44.
45.
Two types of aspartic proteinase (AP) genes have been isolated from the cDNA library of developing buckwheat seeds. Analysis of their sequences showed that one of these, FeAP9, resembled the structure and shared high homology with the so-called typical plant APs characterized by the presence of a plant-specific insert (PSI), an element unique among APs. The other cDNA, FeAPL1, encoded an AP-like protein lacking that domain. Different expression profiles were observed for FeAP9 and FeAPL1. FeAPL1 mRNAs were restricted to the seeds only, whereas FeAP9 mRNAs were also present in the other plant tissues - leaves, roots, and flowers. Higher levels of FeAP9 were observed in senescent leaves compared with green leaves. The differential expression pattern of these two unique APs raises the interesting possibility that these proteinases have unique substrate specificity and may have different roles in plant development and other physiological processes.  相似文献   
46.
The aim of this study was to determine whether deletion 22q11.2 studies should become apart of a standardized diagnostic workup for selected groups of at risk patients. We prospectively investigated four cohorts of unselected patients referred because of 1) congenital heart defect (CHD), 2) palatal anomalies, 3) hypocalcaemia, 4) dysmorphic features suggestive of del 22q11.2. Fluorescence in situ hybridization analysis revealed deletion 22q11.2 in 9.4% (6/64) patients with CHD. From 18 patients referred because of the hypocalcaemia, six (33.3%) had 22q11.2 deletion. In the group of 31 children with dysmorphic traits, the diagnosis was confirmed in two (6.4%) patients. None of the 58 children with palatal anomalies showed evidence of 22q11.2 deletion. Conclusions: Testing for the 22q11.2 microdeletion can be recommended in all patients with conotruncal heart defects and in patients with hypocalcaemia. It should be also considered in patients presenting only with dysmorphic traits suggestive of del 22q11.2, while screening in patients with cleft palate is not warranted.  相似文献   
47.
The aim of this study was to analyse breast carcinomas with discordant receptor status, probably hormonal dependent (estrogen receptor (ER) positive, progesterone receptor (PR) negative or ER-PR + subgroup profile) infiltrating ductal breast carcinomas not otherwise specified (IDC NOS). Specimens from 90 IDC NOS were grouped into three categories according to hormonal status: dependent (D) (ER +PR +), probably dependent (PD) (ER +PR- or ER-PR +) and non-dependent (ND) (ER-PR-); they were evaluated considering some established prognostic parameters in breast carcinomas. Statistically significant difference was found between tumor receptor status distribution and menopausal status (p = 0.0235), age of the patients (p = 0.000467), histological grade (p = 0.000003), vascular invasion (p = 0.006), HER-2 status (p = 0.0039) and Ki-67 proliferation rate (p = 0.000311). D tumors were found exclusively in post-menopausal patients (average age 68.9 years), most of which had intermediate (II) grade, without vascular invasion, with HER-2 status score predominantly 0 or 1 + and lower Ki-67 proliferation rate. PD tumors were found predominantly in younger post-menopausal patients (average age 57.5 years), with vascular invasion found in 23% of the cases. ND tumors mostly had higher histological grade, showed the highest percentage of the Ki-67 positive tumor cells and vascular invasion in 30% of the cases. We conclude that the patients with PD breast carcinomas were younger post-menopausal women with the tumors moderately differentiated, HER-2 score 0 or 1+ and with lower Ki-67 proliferation rate.  相似文献   
48.
Involution displayed by keratoacanthoma (KA) represents an important difference between KA and squamous cell carcinoma (SCC). It has been suggested that apoptosis plays a part in process of involution of KA. Altogether 150 specimens were included in this study, 30 cases of each; normal skin (NS), proliferative (pKA) and regressing keratoacanthoma (rKA), well differentiated (wdSCC) and poorly differentiated (pdSCC) squamous cell carcinoma. All samples were examined immunohistochemically for expression of M30 protein. A significantly lower number of M30 positive cells has been detected in NS as compared to skin tumors examined (p<0.001), except for rKA (p=0.057). The highest percentage of M30 positive cells was detected in pdSCC (p<0.001) as compared with all other examined groups. Keratinocytes of normal and changed epidermis expressing higher levels of M30 protein were predominately found in sun-exposed areas (chi2=14.93; p=0.060). There was an increasing trend of M30 protein expression with increasing age of the patient in NS and skin tumors examined. Majority of skin tumors with higher percentage of M30 positive cells tended to display higher Ki-67 expression. M30 expression was highly correlated with bak (r=0.811; p=0.048) and granzyme B expression in rKA (r=0.733; p=0.015). Cell apoptosis as assessed by M30 expression is, generally, increased in examined skin tumors and related to cell proliferation. Cell apoptosis mediated by bak and granzyme B expression could contribute to KA regression.  相似文献   
49.
Plant and Soil - Phragmites australis grows as a pioneer plant species in several mine and flotation tailings ponds distinguished by extremely high concentrations of metals. The main goals of this...  相似文献   
50.
In the present study, upon showing sexual dimorphism in dimethyl fumarate (DMF) efficacy to moderate the clinical severity of experimental autoimmune encephalomyelitis (EAE) in Dark Agouti rats, cellular and molecular substrate of this dimorphism was explored. In rats of both sexes, DMF administration from the day of immunization attenuated EAE severity, but this effect was more prominent in males leading to loss of the sexual dimorphism observed in vehicle-administered controls. Consistently, in male rats, DMF was more efficient in diminishing the number of CD4+ T lymphocytes infiltrating spinal cord (SC) and their reactivation, the number of IL-17+ T lymphocytes and particularly cellularity of their highly pathogenic IFN-γ+GM-CSF+IL-17+ subset. This was linked with changes in SC CD11b+CD45+TCRαβ? microglia/proinflammatory monocyte progeny, substantiated in a more prominent increase in the frequency of anti-inflammatory phygocyting CD163+ cells and the cells expressing high surface levels of immunoregulatory CD83 molecule (associated with apoptotic cells phagocytosis and implicated in downregulation of CD4+ T lymphocyte reactivation) among CD11b+CD45+TCRαβ– cells in male rat SC. These changes were associated with greater increase in the nuclear factor (erythroid-derived 2)-like 2 expression in male rats administered with DMF. In accordance with the previous findings, DMF diminished reactive nitrogen and oxygen species generation and consistently, SC level of advanced oxidation protein products, to the greater extent in male rats. Overall, our study indicates sex-specificity in the sensitivity of DMF cellular and molecular targets and encourages sex-based clinical research to define significance of sex for action of therapeutic agents moderating autoimmune neuroinflammation-/oxidative stress-related nervous tissue damage.  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