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   288篇
  免费   25篇
  国内免费   1篇
  2023年   5篇
  2022年   5篇
  2021年   14篇
  2020年   14篇
  2019年   30篇
  2018年   25篇
  2017年   11篇
  2016年   20篇
  2015年   14篇
  2014年   24篇
  2013年   35篇
  2012年   28篇
  2011年   22篇
  2010年   14篇
  2009年   6篇
  2008年   10篇
  2007年   11篇
  2006年   9篇
  2005年   3篇
  2004年   6篇
  2003年   2篇
  2001年   2篇
  2000年   1篇
  1998年   1篇
  1997年   1篇
  1991年   1篇
排序方式: 共有314条查询结果,搜索用时 15 毫秒
21.
Angiotensin Converting Enzyme Inhibitors (ACEI) like captopril and enalapril, can induce persistant cough in man. Noscapine, an antitussive alkaloid, can be used to suppress ACEI-induced cough. Some workers have suggested a role for bradykinin in precipitation of ACE-induced cough. Work carried out in our laboratory has shown noscapine to be a non-competitive inhibitor of bradykinin in guinea pig ileum. It is therefore possible that noscapine suppresses cough by blocking the effect of bradykinin receptor activation in the airways. Guinea pigs were placed in a cough-chamber connected to an air pump and a pressure transducer. Capsaicin was sprayed into the chamber and cough was recorded as a distinctive change in air pressure inside the cough-chamber. Animals treated with 1 mg/kg captopril and enalapril for 7 days, showed increased cough response. Ten microgram/kg FR190997, a non-peptide agonist of the bradykinin B2 receptor, also increased the cough response. Noscapine at 0.5, 1 and 2 mg/kg was able to reverse the effects of ACEI and FR190997. Naloxone, a specific opioid receptor inhibitor, did not block the antitussive effects of noscapine in enalapril or FR190997 treated guinea pigs. This antitussive effect of noscapine is not mediated via the mu, kappa or delta opioid receptors. It is therefore possible that noscapine exerts its antitussive action by interfering with the bradykinin cough mediation.  相似文献   
22.
The global pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which started in late 2019, has caused huge social and economic losses. A growing number of investigators are focusing on understanding the interaction of SARS-CoV-2 with host cellular processes to find therapeutic approaches. New data suggest that lipid metabolism may play a significant role in regulating the response of immune cells like macrophages to viral infection, thereby affecting the outcome of the disease. Therefore, understanding the role of lipid metabolism could help develop new therapeutic approaches to mitigate the social and economic cost of coronavirus disease 2019 (COVID-19).  相似文献   
23.
The development of dendritic spines with specific geometry and membrane composition is critical for proper synaptic function. Specific spine membrane architecture, sub-spine microdomains and spine head and neck geometry allow for well-coordinated and compartmentalized signaling, disruption of which could lead to various neurological diseases. Research from neuronal cell culture, brain slices and direct in vivo imaging indicates that dendritic spine development is a dynamic process which includes transition from small dendritic filopodia through a series of structural refinements to elaborate spines of various morphologies. Despite intensive research, the precise coordination of this morphological transition, the changes in molecular composition, and the relation of spines of various morphologies to function remain a central enigma in the development of functional neuronal circuits. Here, we review research so far and aim to provide insight into the key events that drive structural change during transition from immature filopodia to fully functional spines and the relevance of spine geometry to function.  相似文献   
24.
25.
26.
To evaluate the chemotaxonomic significance of the essential oils of 23 populations of 18 Iranian Ferula species, the chemical composition of the oils was investigated by GC/FID and GC/MS. Altogether, 84 constituents, representing 81.3-99.7% of the total composition of the oils, have been identified. The composition of six species of the genus, i.e., F. oopoda, F. foetida, F. behboudiana, F. diversivittata, F. galbaniflua, and F. hezarlalehzarica, has been reported for the first time. The main constituents identified were α-terpinyl acetate (73.3%), 2,3,4-trimethylthiophene (2; 49.0%), sabinene (75.3%), verbenone (5; 69.4%), β-pinene (59.0-66.3%), and (Z)-β-ocimene (41.7%). Cluster analysis (CA) of the percentage content of the essential oil components of the Ferula species resulted in the characterization of four groups, i.e., taxa containing either i) monoterpene hydrocarbons, ii) oxygenated monoterpenes, iii) organosulfur compounds, or iv) monoterpene, sesquiterpene, and aliphatic hydrocarbons as the principal classes of compounds. Based on the results obtained, the chemical independence of F. hirtella from F. szowitsiana and of F. galbaniflua from F. gummosa at the specific level was concluded and their positions as distinct species were confirmed. The chemotaxonomic relationships among the representatives of the genus Ferula have been discussed in detail.  相似文献   
27.
To determine the LC50 values of two entomopathogenic nematodes against Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae) prepupae, different concentrations of the nematodes were tested in soil. Because of the different temperature requirements of the two nematode species, bioassay experiments were conducted at 20 ± 1°C and 27 ± 2°C for Steinernema feltiae Filipjev (Rhabditida: Steinernematidae) and Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), respectively. Both the isolates were effective against L. decemlineata. LC50 values of H. bacteriophora against progeny of field-collected adults and laboratory-reared adults were estimated as 8.5 and 7.6 IJ per prepupa, respectively. For S. feltiae the value was calculated as 51.2 IJ per prepupa against offspring of laboratory-reared adults of L. decemlineata only. Cellular encapsulation of both nematode species was observed. Sublethal nematode concentrations caused wing deformation and delayed metamorphosis which may affect Colorado potato beetle adult fitness.  相似文献   
28.
The in vitro antibacterial and antioxidant activity of the essential oil and its two main components of Grammosciadium scabridum Boiss. (Apiaceae) growing wild in Iran, as well as the composition of its essential oil were studied. A total of 19 compounds representing 99.9% of the oil has been identified. Gamma-Terpinene (73.5%), p-cymene (14.2%) and (E)-beta-farnesene (5.3%) were characterized as the main components. The oil showed remarkable activity against three Gram-negative and four Gram-positive test bacteria, with minimal inhibitory concentration (MIC) values ranging from 0.31 to 10.00 mg/ml. The oil and its two main components were also subjected to screening for their possible antioxidant activity by using the 2,2-diphenyl-l-picrylhydrazyl (DPPH) assay. The free radical scavenging capacity of the oil was determined with an IC50 value of 6.6 mg/ml.  相似文献   
29.
Invasive aspergillosis increases in chronic immunosuppressive diseases such as cancer. There is little information about the mechanisms by which Aspergillus infection affects the immune regulation and microenvironment of cancer cells. Hence, this study was aimed at investigating the effect of invasive aspergillosis on immunosurveillance, metastasis, and prognosis of cancer in tumor-bearing mice. After implantation of mouse mammary tumor in BALB/c mice, they were infected with Aspergillus conidia intravenously. For comparison, groups of mice were experimentally infected with Aspergillus conidia or implanted with tumor cells separately. Seven days after Aspergillus infection, the serum levels of tissue inhibitor of metalloproteinase-1 (TIMP-1) were measured by ELISA, and subsequently regulatory T lymphocytes were analyzed by flow cytometry. The survival of animals and mean tumor size were then determined. Our results indicated that tumor sizes in mice increased significantly after infection with Aspergillus conidia. Moreover, invasive aspergillosis enhanced the population of regulatory lymphocytes and level of TIMP-1. This study supports the idea that massive Aspergillus infection could stimulate tumor growth and increases the possibility of a bad prognosis. As a result, treatment of Aspergillus infection could be considered an important issue for efficient cancer therapy.  相似文献   
30.
Today, biologic prodrugs have led to targeting specific tumor markers and have increased specificity and selectivity in cancer therapy. Various studies have shown the role of ncRNAs in cancer pathology and tumorigenesis and have suggested that ncRNAs, especially miRNAs, are valuable molecules in understanding cancer biology and therapeutic processes. Most miRNAs-based research and treatment are limited to chemically synthesized miRNAs. Synthetic alterations in these miRNA mimics may affect their folding, safety profile, and even biological activity. However, despite synthetic miRNA mimics produced by automated systems, various carriers could be used to achieve efficient production of bioengineered miRNAs through economical microbial fermentation. These bioengineered miRNAs as biological prodrugs could provide a new approach for safe therapeutic methods and drug production. In this regard, bioengineered chimeric miRNAs could be selectively processed to mature miRNAs in different types of cancer cells by targeting the desired gene and regulating cancer progression. In this article, we aim to review bioengineered miRNAs and their use in cancer therapy, as well as offering advances in this area, including the use of chimeric tRNA/pre-miRNAs.  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