全文获取类型
收费全文 | 284篇 |
免费 | 4篇 |
国内免费 | 9篇 |
出版年
2023年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 7篇 |
2014年 | 3篇 |
2013年 | 6篇 |
2012年 | 6篇 |
2011年 | 9篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 11篇 |
2007年 | 17篇 |
2006年 | 16篇 |
2005年 | 16篇 |
2004年 | 17篇 |
2003年 | 10篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1997年 | 7篇 |
1996年 | 11篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 14篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1974年 | 2篇 |
排序方式: 共有297条查询结果,搜索用时 15 毫秒
41.
以次生代谢物质萜烯类、黄酮类以及单宁等为基础的自身化学抗虫性一直是植物化学防御的核心.随着基因重组技术的发展,许多作物获得了一种新的化学防御形式,即以表达外源基因产物来进行防御.外源抗虫蛋白与内源抗虫物质的协调性问题,在利用外源基因工程改良植物抗虫性时是非常重要的,同时也是转基因作物安全性和生态学评价的重要方面.转基因植物中外源与内源抗虫系统间的协调性的研究取得了一些成果,但尚未引起人们足够的重视.综述了离体条件下和在转基因植物体内,外源抗虫蛋白Bt和GNA等与植物次生代谢物质以及各抗虫蛋白之间交互作用的研究进展,并探讨了研究各抗虫因子交互作用的意义. 相似文献
42.
Wysocka M Lesner A Guzow K Mackiewicz L Legowska A Wiczk W Rolka K 《Analytical biochemistry》2008,378(2):208-215
In this study, chemical synthesis of the selective chromogenic/fluorogenic substrates for proteinase 3 is described. The substrates’ sequence was obtained using combinatorial chemistry methods. Deconvolution of the tripeptide library against proteinase 3 with general formula ABZ-X3-X2-X1-ANB-NH2 yielded the active sequence. Selected peptide was further modified on its C terminus to investigate the impact of chromophore moiety modification on enzyme-substrate interaction. To determine specificity, activity of selected substrates was characterized against proteinase 3 and neutrophil elastase. Finally, the peptide ABZ-Tyr-Tyr-Abu-ANB-NH2 displayed the highest value of specificity constant (kcat/KM = 189 × 103 M−1 s−1) for proteinase 3. To the best of our knowledge, this is the first short peptide that undergoes selective proteolysis by proteinase 3 and displays no significant hydrolysis in the presence of human neutrophil elastase and cathepsin G. 相似文献
43.
渤海水母体细菌的微生态分布及弧菌生物学特性 总被引:2,自引:2,他引:0
采用稀平板法对我国辽宁渤海海域水母体中细菌的微生态分布进行了考察,结果表明,在渤海水母体中各部位均有腐生性细菌及弧菌生长,其中腐生性细菌主要存在于水母体现,而弧菌除存在于水母体表外,有的则能在水母体内深层生长,水母体细菌微生态研究结果表明,弧菌的占细菌总数的90%以上,通过改进TCBAS培养基,从水母体中分离得到6株优势类群的细菌,对其菌落特征、菌体形态、生理生化特性进行了研究,它们都具备弧菌属的共同特点:革兰氏阴性,氧化酶阳性,兼性厌氧,TCBS培养基上能生长,对O/129敏感,初步鉴定为弧菌属,研究还发现,这几株菌都能产蛋白酶,其中JF2、JF4、JF5、JF6产蛋白酶的能力明显较强,它们极有可能是导致水母捕捞后快速解体腐败的主要原因。 相似文献
44.
Abstract In Saccharomyces cerevisiae heat-shock induces an increase in proteinase activity. The induction is probably due to newly synthesized enzyme molecules, since the increase in proteinase activity can be inhibited by cycloheximide. Degradation of endogenous proteins is enhanced by EDTA, while the azocasein assay is not affected by MnCl2 , MgCl2 , or EDTA. The proteinase has a pH optimum of 8, and phenylmethylsulfonyl fluoride (PMSF) as well as chymostatin are strong inhibitors. We infer that the induced proteinase is probably identical with proteinase B of yeast. 相似文献
45.
《Structure (London, England : 1993)》2020,28(10):1149-1159.e4
- Download : Download high-res image (192KB)
- Download : Download full-size image
46.
A. Hasilik 《Archives of microbiology》1974,101(1):295-301
The activity of chitin synthase extracted from whole cells of Saccharomyces cerevisiae shows reproducible changes during the course of batch cultivation. During exponential growth 5–10% of the enzyme occurs in the active form, whereas in the stationary phase no active enzyme can be detected. Of three yeast proteinases, A, B and C, only B is able to activate pre-chitin synthase and inactivate chitin synthase. A new model of the regulation is presented which accounts for the specific location as well as for termination of chitin synthesis during the budding cycle.These results were reported at the 4th International Symposium on Yeasts in Vienna, July 1974, and are part of doctoral thesis by A.H., University Freiburg (1974). 相似文献
47.
Dorothea Köhle Heinrich Kauss 《Biochimica et Biophysica Acta (BBA)/General Subjects》1984,799(1):59-67
UDPgalactose:sn-glycerol-3-phosphate α-D-galactosyltransferase (IFP-synthase, EC 2.4.1.96) shows low activity in extracts prepared from standard volume cells of Poterioochromonals malhamensis under certain conditions. This inactive enzyme has been partially purified by chromatography on DEAE-cellulose, Sephadex G-150 and α-lactalbumin-agarose. It can be activated by an auxiliary enzyme which can be eluted from membranes and which has been purified to homogeneity by chromatography on DEAE-Sephacel and immobilized hemoglobin and fetuin. The activating enzyme is inhibited by chymostatin, antipain and diisopropylfluorophosphate and does not require divalent ions. It consists of a single peptide chain of molecular weight 46 000, can split certain proteins and appears to be a serine proteinase operating around a pH of 6.0. The activating proteinase is irreversibly generated in the crude homogenates on addition of Ca2+ and also shows increased activity shortly after cell shrinkage. This might indicate that it represents one of the possibilities to render the galactosyltransferase active as a result of the physiological stimulus. 相似文献
48.
Specificity in the induced responses of tomato foliage to arthropod herbivores was investigated. We distinguished between
two aspects of specificity: specificity of effect (the range of organisms affected by a given induced response), and specificity
of elicitation (ability of the plant to generate distinct chemical responses to different damage types). Specificity of effect
was investigated by examining the effect of restricted feeding by Helicoverpa zea on the resistance of tomato plants to an aphid species (Macrosiphum euphorbiae), a mite species (Tetranychus urticae), a noctuid species (Spodoptera exigua), and to a phytopathogen, Pseudomonas syringae pv. tomato. Prior H. zea feeding was found to increase the resistance of tomato plants to all four organisms. Specificity in elicitation was investigated
by examining the effect of aphid feeding on the activities of four defense-related proteins and on the suitability of foliage
for S. exigua. Aphid feeding was found to induce peroxidase and lipoxygenase activities but not polyphenol oxidase and proteinase inhibitor
activities; this response is distinct from the response to H. zea feeding, which induces polyphenol oxidase and proteinase inhibitors but not peroxidase. Leaflets which had been fed upon
by aphids were better sources of food for S. exigua than were leaflets which had not been fed upon by aphids. Studies of both these aspects of specificity are needed to understand
the way in which plants coordinate and integrate induced responses against insects with other physiological processes.
Received: 20 December 1996 / Accepted: 2 July 1997 相似文献
49.
Bonacci GR Cáceres LC Sánchez MC Chiabrando GA 《Archives of biochemistry and biophysics》2007,460(1):100-106
The low-density lipoprotein receptor-related protein-1 (LRP-1) is an endocytic receptor of activated forms of the proteinase inhibitor alpha(2)-macroglobulin (alpha(2)M*). It has been proposed that alpha(2)M* and LRP-1 modulate diverse cellular processes, including cell adhesion, proliferation, and migration, which are involved in inflammation and tumor progression. However, relatively little is known about the role of alpha(2)M*/LRP-1 interaction on these processes. In this work, we demonstrate that alpha(2)M* binding to LRP-1 induces cell proliferation and MAPK activation in the J774 macrophage-derived cell line, which were blocked by RAP, an antagonist of LRP-1-binding ligands, and by PD980059, a specific inhibitor for the Mek1-ERK1/2 pathway. In addition, we demonstrate that LPS, a bacterial product that it is known to down-regulate the LRP-1 expression on macrophage, abrogated the signaling activity triggered by alpha(2)M* on LPS-treated J774 cells. These results suggest that alpha(2)M*/LRP-1 interaction constitutes a key role in the macrophage functioning during inflammation and cancer. 相似文献
50.