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   165篇
  免费   2篇
  2023年   2篇
  2022年   4篇
  2021年   14篇
  2020年   10篇
  2019年   37篇
  2018年   5篇
  2017年   2篇
  2016年   6篇
  2015年   8篇
  2014年   12篇
  2013年   9篇
  2012年   9篇
  2011年   9篇
  2010年   6篇
  2009年   5篇
  2008年   4篇
  2007年   5篇
  2006年   6篇
  2005年   3篇
  2004年   5篇
  2003年   2篇
  1998年   1篇
  1995年   1篇
  1985年   1篇
  1975年   1篇
排序方式: 共有167条查询结果,搜索用时 15 毫秒
41.
Swallowed volumes in the fetus are greater than adult values (per body weight) and serve to regulate amniotic fluid volume. Central ANG II stimulates swallowing, and nonspecific ANG II receptor antagonists inhibit both spontaneous and ANG II-stimulated swallowing. In the adult rat, AT1 receptors mediate both stimulated drinking and pressor activities, while the role of AT2 receptors is controversial. As fetal brain contains increased ANG II receptors compared with the adult brain, we sought to investigate the role of both AT1 and AT2 receptors in mediating fetal swallowing and pressor activities. Five pregnant ewes with singleton fetuses (130 +/- 1 days) were prepared with fetal vascular and lateral ventricle (LV) catheters and electrocorticogram and esophageal electromyogram electrodes and received three studies over 5 days. On day 1 (ANG II), following a 2-h basal period, 1 ml artificial cerebrospinal fluid (aCSF) was injected in the LV. At time 4 h, ANG II (6.4 microg) was injected in the LV, and the fetus was monitored for a final 2 h. On day 3, AT1 receptor blocker (losartan 0.5 mg) was administered at 2 h, and ANG II plus losartan was administered at 4 h. On day 5, AT2 receptor blocker (PD-123319; 0.8 mg was administered at 2 h and ANG II plus PD-123319 at 4 h. In the ANG II study, LV injection of ANG II significantly increased fetal swallowing (0.9 +/- 0.1 to 1.4 +/- 0.1 swallows/min; P < 0.05). In the losartan study, basal fetal swallowing significantly decreased in response to blockade of AT1 receptors (0.9 +/- 0.1 to 0.4 +/- 0.1 swallows/min; P < 0.05), while central injection of ANG II in the presence of AT1 receptor antagonism did not increase fetal swallowing (0.6 +/- 0.1 swallows/min). In the PD-123319 study, basal fetal swallowing did not change in response to blockade of AT2 receptor (0.9 +/- 0.1 swallows/min), while central injection of ANG II in the presence of AT2 blockade significantly increased fetal swallowing (1.5 +/- 0.1 swallows/min; P < 0.05). ANG II caused significant pressor responses in the control and PD-123319 studies but no pressor response in the presence of AT1 blockade. These data demonstrate that in the near-term ovine fetus, AT1 receptor but not AT2 receptors accessible via CSF contribute to dipsogenic and pressor responses.  相似文献   
42.
The biodiversity of Trichoderma was studied in the Northern half of the Nile valley in Egypt. 20 strains were isolated from 9 different geographic locations, representing 19 different habitats, all with a pH between 7.3 and 8.4. Only T. harzianum (three ITS1/2 haplotypes and three RAPD-genotypes) and the anamorph of Hypocrea orientalis were found. One of the T. harzianum haplotypes (4 strains) is new. The occurrence of T. harzianum haplotypes and of H. orientalis appeared to be essentially independent of the habitat (pH, plant, soil type), and also did not correlate with biochemical properties (cellulase and chitinase activity) of the individual strains. These two taxa seem to be indigenous to the Nile valley, their presence not being influenced by the agricultural history of the soils.  相似文献   
43.
Diabetes is one of the most prevalent diseases in the worldwide. Type 2 diabetes mellitus (T2DM), the most common form of the disease, has become a serious threat to public health and is a growing burden on global economies. Due to the unexpected adverse effects of antidiabetic medicines, the use of nutraceuticals as a complementary therapy has drawn extensive attention by investigators. In this issue, a novel nutraceutical, Punicic acid (PA)—the main ingredient of pomegranate seed oil (PSO) that has potential therapeutic effects in T2DM—has been investigated. PA is a peroxisome proliferator-activated receptor gamma agonist, and unlike synthetic ligands, such as thiazolidinediones, it has no side effects. PA exerts antidiabetic effects via various mechanisms, such as reducing inflammatory cytokines, modulating glucose homeostasis, and antioxidant properties. In this review, we discussed the potential therapeutic effects of PSO and PA and represented the related mechanisms involved in the management of T2DM.  相似文献   
44.
45.
Plasmodium falciparum, the mosquito-transmitted Apicomplexan parasite, causes the most severe form of human malaria. In the asexual blood-stage, the parasite resides within erythrocytes where it proliferates, multiplies and finally spreads to new erythrocytes. Development of drugs targeting the ribosome, the site of protein synthesis, requires specific knowledge of its structure and work cycle, and, critically, the ways they differ from those in the human host. Here, we present five cryo-electron microscopy (cryo-EM) reconstructions of ribosomes purified from P. falciparum blood-stage schizonts at sub-nanometer resolution. Atomic models were built from these density maps by flexible fitting. Significantly, our study has taken advantage of new capabilities of cryo-EM, in visualizing several structures co-existing in the sample at once, at a resolution sufficient for building atomic models. We have discovered structural and dynamic features that differentiate the ribosomes of P. falciparum from those of mammalian system. Prompted by the absence of RACK1 on the ribosome in our and an earlier study we confirmed that RACK1 does not specifically co-purify with the 80S fraction in schizonts. More extensive studies, using cryo-EM methodology, of translation in the parasite will provide structural knowledge that may lead to development of novel anti-malarials.  相似文献   
46.
Host resistance to Leishmania infection is mediated by cellular immune responses leading to macrophage activation and parasite killing. Interleukin-18 (IL-18) known as interferon-γ (IFN-γ) inducing factor, stimulates IFN-γ production by T cells. Taking into account the important role of IL-18 in the defense against visceral leishmaniasis (VL) and the known effect of IL-18 gene polymorphisms on its production, the aim of this study was to investigate the probable relationship between IL-18 gene polymorphisms and the susceptibility to VL. The study groups included 118 pediatric patients who suffered from VL and 156 non-relative healthy people as the controls from the same endemic area. IL-18 gene polymorphisms at the positions ?656 G/T, ?137 G/C and +105A/C (codon 35/3) were analyzed by polymerase chain reaction-restricted fragment length polymorphism (PCR–RFLP). The results showed that the frequency of T allele at the position -656 was significantly higher in the controls, compared with that in the patients (P = 0.047), but it couldn’t tolerate Bonferroni correction. Regarding the IL-18 genotypes, there was no significant difference between the patients and controls. Although the frequencies of ATG single haplotype and AGG/ATG double haplotype were significantly higher in the controls (P = 0.043) and the patients (P = 0.044), respectively, the two P values couldn’t tolerate Bonferroni correction. Furthermore, a strong linkage disequilibrium was observed among the ?656, ?137 and +105 single nucleotide polymorphisms of IL-18 gene (all Ps < 0.001). In conclusion, this study suggests that the inheritance of T allele at the position ?656 may be considered as a genetic factor for resistance to VL.  相似文献   
47.
48.
There is insufficient evidence with respect to the effect of the standard anticancer therapeutic agents as well as common dietary supplements on the expression of such genes and microRNAs (miRNAs). Therefore, this study was aimed to study the effect of applying linoleic acid (LA) and docosahexaenoic acid (DHA) fatty acids alone or combined with Taxol on the expression of the matrix metalloproteinase (MMP)-9, MMP-2, vimentin, and talin2 genes, tumor-suppressor miR-194 and, onco-miR-106b in triple-negative breast cancer cell line, known as MDA-MB-231. MDA-MB-231 as metastatic breast cancer cell line was cultured and treated using 0.3 μM Taxol, 100 μM DHA, and 50 μM LA for 24 hours, alone or combined with Taxol under the normoxic and hypoxic conditions. Cells were harvested, after RNA extraction and complementary DNA synthesis, analysis of the expression levels of the studied genes and miRNAs was done through the use of the quantitative real-time polymerase chain reaction (qRT-PCR). Wound healing assay and Western blot analysis were also performed for confirmation. The results of qRT-PCR showed that treating the MDA-MB-231 cells with DHA caused an increase in the miR-194 expression and a decrease in the miR-106b expression, leading to the downregulation of the MMP-2 and MMP-9, and vimentin, and upregulation of the talin2 under the normoxic and hypoxic conditions. The results of the wound healing scratch assay revealed that the administration of the DHA and the DHA-Taxol combination caused the repression of cell migration in comparison with the control groups under the normoxic and hypoxic conditions. The results of the Western blot analysis demonstrated that DHA and the DHA-Taxol combination caused an increase in the expression of the talin2 protein rather than the control cells under both normoxic and hypoxic conditions. This study showed that DHA has significant antimetastatic effects against the triple-negative breast cancer cells. DHA could serve as a promising supplementation for suppressing the breast cancer cell migration, especially under the hypoxic condition.  相似文献   
49.
Melanoma skin cancer is one of the main causes of male cancer-related deaths worldwide. It has been suggested that miR-330-5p can act as a tumor suppressor in various types of cancers. So, in this study, we replaced miR-330 in melanoma cancer cells by vector-based miR-330 to evaluate the effects of this microRNA on the growth and migration inhibition of melanoma cancer cells, and to determine the molecular mechanisms underlying its action. By using the MTT assay, the IC50 of Geneticin antibiotic was obtained as 460 µg/mL. The results of the qRT-PCR showed the increased expression level of miR-330 and decreased expression levels of MMP-9, CXCR4, Vimentin, melanoma cell adhesion molecule, AKT1, and E2F1 messenger RNA in A375 transfected cells. The cytotoxicity assay results demonstrated the inhibition of cancer cells proliferation. Furthermore, the wound healing test results showed a migration reduction of transfected cells with miR-330 compared with nontransfected ones. In addition, 4′,6-diamidino-2-phenylindoleLB: Luria-Bertani (DAPI) staining revealed the significant nucleus fragmentation in miR-330 replaced cells, which correspond to apoptosis induction in replaced cells. The results showed that increase in miR-330 expression level could significantly inhibit the tumor cell growth and the migration of melanoma cancer cells.  相似文献   
50.
The relationship between intakes of fluoride (F) from drinking water and blood pressure has not yet been reported. We examined the relationship of F in ground water resources (GWRs) of Iran with the blood pressure of Iranian population in an ecologic study. The mean F data of the GWRs (as a surrogate for F levels in drinking water) were derived from a previously conducted study. The hypertension prevalence and the mean of systolic and diastolic blood pressures (SBP & DBP) of Iranian population by different provinces and genders were also derived from the provincial report of non-communicable disease risk factor surveillance of Iran. Statistically significant positive correlations were found between the mean concentrations of F in the GWRs and the hypertension prevalence of males (r?=?0.48, p?=?0.007), females (r?=?0.36, p?=?0.048), and overall (r?=?0.495, p?=?0.005). Also, statistically significant positive correlations between the mean concentrations of F in the GWRs and the mean SBP of males (r?=?0.431, p?=?0.018), and a borderline correlation with females (r?=?0.352, p?=?0.057) were found. In conclusion, we found the increase of hypertension prevalence and the SBP mean with the increase of F level in the GWRs of Iranian population.  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