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   188篇
  免费   1篇
  189篇
  2023年   1篇
  2021年   3篇
  2020年   1篇
  2018年   1篇
  2015年   6篇
  2014年   9篇
  2013年   8篇
  2012年   13篇
  2011年   9篇
  2010年   8篇
  2009年   8篇
  2008年   8篇
  2007年   11篇
  2006年   1篇
  2005年   3篇
  2004年   8篇
  2003年   4篇
  2002年   7篇
  2001年   6篇
  2000年   11篇
  1999年   3篇
  1998年   2篇
  1997年   1篇
  1996年   4篇
  1995年   2篇
  1994年   1篇
  1993年   1篇
  1992年   3篇
  1991年   2篇
  1990年   4篇
  1989年   4篇
  1988年   2篇
  1987年   1篇
  1986年   4篇
  1985年   2篇
  1984年   2篇
  1983年   3篇
  1982年   3篇
  1981年   1篇
  1980年   4篇
  1979年   3篇
  1978年   1篇
  1977年   2篇
  1976年   1篇
  1975年   2篇
  1970年   1篇
  1968年   1篇
  1930年   1篇
  1928年   1篇
  1900年   1篇
排序方式: 共有189条查询结果,搜索用时 15 毫秒
1.
Two phosphatidylcholines containing hydroxylated fatty acids, 1-palmitoyl-2-[5-hydroxy-6,8,11,14-eicosatetraenoyl]-sn-glycero-3- phosphocholine (1-palm-2-5HETE PC) and 1-palmitoyl-2-[15(S)-hydroxy-5,8,11,13- eicosatetraenoyl]-sn-glycero-3-phosphocholine (1-palm-2-15HETE PC), and one phosphatidylcholine containing nonhydroxylated fatty acids, 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphocholine (1-palm-2-arach PC) were synthesized. Permeation of small nonelectrolytes (glycerol, 1,2-propanediol, urea, methylurea, propionamide and dimethylformamide) was assessed in multilamellar liposomes containing these synthetic PCs plus egg yolk phosphatidycholine (EPC) in the presence and absence of cholesterol. In liposomes containing 23% cholesterol, 69.3% EPC and 7.7% of either 1-palm-2-5HETE PC or 1-palm-2-15HETE PC the permeability to small nonelectrolytes was 60 to 400% greater than in liposomes containing 23% cholesterol and 77% EPC. The HETE-containing PCs also increased permeability in liposomes without cholesterol but the effects were less striking. Addition of the synthetic PCs did not affect the energy of activation of permeation.  相似文献   
2.
Summary Intercellular junctions in the uterine epithelium of the ovoviviparous urodele Salamandra salamandra were studied in pregnant and non-pregnant females by freeze-fracture technique. Junctional complexes consist of zonulae occludentes (tight junctions) and numerous maculae adhaerentes (desmosomes); z. adhaerentes and nexuses (gap junctions) could not be identified. Tight junctions are of the flexible type exhibiting loosely interconnected fibrils. The fibrillary network appears stretched more often in pregnant females possibly due to the mechanical stress of pregnancy. The structure and occurrence of the junctions identified, especially that of the tight junctions, is discussed with regard to the functions of the uterus during pregnancy.Zusammenfassung Mit Hilfe der Gefrierbruchtechnik wurden im Uterus-epithel trächtiger und nichtträchtiger Feuersalamanderweibchen (Salamandra salamandra) Zonulae occludentes und Maculae adhaerentes, jedoch keine Z. adhaerentes sowie Nexus identifiziert. Die Z. occludentes sind flexibel. Ihr fibrilläres Netzwerk ist bei trächtigen Weibchen öfter gestreckt; das ist möglicherweise auf die stärkere Ausdehnung des Uterusgewebes während der Trächtigkeit zurückzuführen. Das Vorkommen der verschiedenen Kontakt-strukturen, namentlich das der Z. occludentes, wird im Hinblick auf die Funktionen des Uterus während der Trächtigkeit diskutiert.We are indebted to Mrs. K. Ott for excellent technical assistance and to Miss Dr. U. Beigel for linguistic help  相似文献   
3.
Cells of a mouse macrophage-like tumor cell line, J774.2, were incubated with 0.6μM radiolabeled mono- and di-hydroxyfatty acids. Monohydroxyfatty acid products of the neutrophil and platelet lipoxygenase pathways (5-HETE, 15-HETE, and 12-HETE) were rapidly taken up (42–64% of the counts cell associated at 1 min) and esterified into triglycerides and phospholipids. 5-HETE and 12-HETE were found in triglycerides and distributed among phospholipid classes while 50% of added 15-HETE was esterified into phosphatidyl inositol. Treatment of phospholipids from cells incubated with 5-HETE, 12-HETE, and 15-HETE with phospholipase A2 resulted in release of the respective monohydroxyfatty acid. HHT, a monohydroxyfatty acid product of the cyclooxygenase pathway, was taken up and esterified more slowly than the lipoxygenase products. In addition, HHT was not released when the phospholipids from cells incubated with HHT were treated with phospholipase A2. LTB4, a dihydroxyfatty acid product of neutrophil lipoxyegnase, was not taken up by J774.2 cells. The unique patterns of uptake and intracellular distribution of the different monohydroxyfatty acids suggests that the enzymes involved in the esterification of these compounds have substrate specificity and may also relate to the specific biologic effects of the compounds.  相似文献   
4.
Summary Results of investigations on the occurrence of nerve fibres and endings in the synovial membrane of the knee and elbow joint in the cat are reported. The stratum synoviale contains only autonomic fibres, running in the adventitia of arteries.Free nerve endings are lacking in the stratum synoviale. Simple Pacinian corpuscles with an inner core are occasionally observed in the border zone between the stratum synoviale and fibrosum. The ultrastructure of these endorgans resembles that of Pacinian corpuscles in the hairless and hairy skin of the cat.  相似文献   
5.
Typical civilization diseases, such as type II diabetes, are common, complex in the underlying pathogenic mechanisms, heterogenous in the phenotype and multifactorial due to a wide variety of possible combinations of disease susceptibility or protective genes in different relevant tissues and negative or positive environmental factors. This is in sharp contrast to classical inherited diseases, such as Chorea Huntington, which are often caused by complete loss‐ or gain‐of‐function mutations in a single gene. The causative polymorphisms of susceptibility genes, however, are characterized by relative subtle alterations in the function of the corresponding gene product, which per se do not support the pathogenesis, by high frequency, high expenditure for their identification and rather low predictive value. Consequently, the reliable and early diagnosis of civilization diseases depends on the individual determination of all (or as many as possible) polymorphisms of each susceptibility gene together with the corresponding gene products and the metabolites emerging thereof.  相似文献   
6.
Mutation position imaging toolbox (MuPIT) interactive is a browser-based application for single-nucleotide variants (SNVs), which automatically maps the genomic coordinates of SNVs onto the coordinates of available three-dimensional (3D) protein structures. The application is designed for interactive browser-based visualization of the putative functional relevance of SNVs by biologists who are not necessarily experts either in bioinformatics or protein structure. Users may submit batches of several thousand SNVs and review all protein structures that cover the SNVs, including available functional annotations such as binding sites, mutagenesis experiments, and common polymorphisms. Multiple SNVs may be mapped onto each structure, enabling 3D visualization of SNV clusters and their relationship to functionally annotated positions. We illustrate the utility of MuPIT interactive in rationalizing the impact of selected polymorphisms in the PharmGKB database, somatic mutations identified in the Cancer Genome Atlas study of invasive breast carcinomas, and rare variants identified in the exome sequencing project. MuPIT interactive is freely available for non-profit use at http://mupit.icm.jhu.edu.  相似文献   
7.
Tailor‐made microorganisms Microbial diversity provides unlimited resources for the development of novel industrial processes and products. Since the beginning of the 20th century microorganisms have been successfully applied for the large scale production of bio‐based products. In recent years, modern methods of strain development and Synthetic Biology have enabled biotech engineers to design even more sophisticated and tailor‐made microorganisms. These microbes serve industrial processes for the production of bulk chemicals, enzymes, polymers, biofuels as well as plant‐derived ingredients such as Artemisinin in an ecologically and economically sustainable and attractive fashion. In the future, production of advanced biofuels, microbial fuel cells, CO2 as feedstock and microbial cellulose are research topics as well as challenges of global importance. Continuous efforts in microbiology and biotechnology research will be pivotal for white biotechnology to gain more momentum in transforming the chemical industry towards a knowledge based bio‐economy.  相似文献   
8.
9.
10.
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