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排序方式: 共有185条查询结果,搜索用时 797 毫秒
161.
应用代谢工程方法对Corynebacterium glutamicum ATCC 13032生物合成乙偶姻进行了研究.在C.glutamicum ATCC 13032中导入了Bacillus subtilis 168的乙偶姻合成途径的相关基因als SD操纵子,工程菌株的乙偶姻产量为2.14,g/L.为了增加合成乙偶姻的直接前体物丙酮酸的供给,进一步敲除了丙酮酸脱氢酶复合体E1亚基的编码基因(ace E)和乳酸脱氢酶基因(ldh A),工程菌株的乙偶姻产量提高到5.09,g/L.最后,敲除了工程菌株的2,3-丁二醇脱氢酶基因(but A)以阻断副产物2,3-丁二醇的合成,在优化的溶氧条件下,菌株CGL3在基本培养基中乙偶姻产量提高到8.33,g/L,达到理论得率的51.5%.实验结果表明经过代谢工程改造的C.glutamicum ATCC 13032具有良好的乙偶姻合成能力和应用潜力. 相似文献
162.
高兴林 《暨南大学学报(自然科学与医学版)》1998,(6)
探讨吸入一氧化氮(NO)对缺氧性肺动脉高压患者一氧化氮合酶(NOS)和内皮素(ET)的影响。方法:13例肺动脉高压患者行NO吸入,分别于吸入NO前、吸入30min时、停止吸入2h和12h时采肺动脉血,测白细胞中的NOS及血浆中的ET。结果:吸入NO前、吸入30min时、停止吸入2h和12h,所测NOS值分别为(070±0.21)mol/min·mg-1、(074±014)mol/min·mg-1、(064±022)mol/min·mg-1和(063±017)mol/min·mg-1;所测ET为(7889±4659)pmol/L、(8827±4541)pmol/L、(8076±4266)pmol/L和(6107±29.44)pmol·L-1;后三者同吸入前比,均P>005。结论:缺氧性肺高压患者吸入NO对机体NOS和ET未见明显影响 相似文献
163.
Glutamate synthase is a complex iron-sulfur flavoprotein that forms l-glutamate from l-glutamine and 2-oxoglutarate. It participates
with glutamine synthetase in ammonia assimilation processes. The known structural and biochemical properties of glutamate
synthase from Azospirillum brasilense, a nitrogen-fixing bacterium, will be discussed in comparison to those of the ferredoxin-dependent enzyme from photosynthetic
tissues and of the eukaryotic reduced pyridine nucleotide-dependent form of glutamate synthase in order to gain insight into
the mechanism of the glutamate synthase reaction. Sequence analyses also revealed that the small subunit of bacterial glutamate
synthase may be the prototype of a novel class of flavin adenine dinucleotide- and iron-sulfur-containing oxidoreductase widely
used as an enzyme subunit or domain to transfer reducing equivalents from NAD(P)H to an acceptor protein or protein domain.
Received 10 November 1998, received after revision 10 December 1998; accepted 10 December 1998 相似文献
164.
A series of Benzisolselenazolone (BISA) derivatives were synthesized and evaluated for their antibacterial activities againstE coli. by using LKB-2277 bioactivity monitor. Other bioactivities were tested by the method of High Throughput Screening for pharmaceutical
activity compounds (HTP) BISA derivatives 3b, at the concentration of 40 μg/mL, showed 100% antibacterial activity and 62%
inhibition rate of aldose reductase (at the concentration of 5μg/mL). These new compound structures have determined by IR,1H NMR and MS spectra.
Foundation item: Supported by Hubei Province Natural Science Fund (99J056)
Biography: Yang Li-ping (1975-), female, Master, research direction: organic seleno-compound, antioxidation medicines, selenium-enriched
garlic. 相似文献
165.
166.
胸苷酸合成酶抑制剂雷替曲塞的合成 总被引:5,自引:0,他引:5
以L-谷氨酸二乙酯为手性元,采用汇聚合成法分剐以2-氨基-5-甲基-苯甲酸为原料经环合、溴化制得2-甲基-6-溴甲基-3-氢-喹唑啉-4-酮(4),收率为69.1%;以2-噻吩甲醛为原料经硝化、氧化、酰氯化、缩合、还原及N-甲基化制得N—[5-(N-甲氨基)-2-噻吩甲酰基]-L-谷氨酸二乙酯(3),收率为25.4%;2-噻吩甲醛以硝酸-乙酸酐硝化后再经过氧化氢氧化制备5-硝基噻吩-2-甲酸,收率为62.2%;N-(5-氨基-噻吩-2-甲酰基)-L-谷氨酸二乙酯(10)的N-甲烷化反应中采用胺与碘甲烷摩尔比1:1.1,一次性加入碘甲烷,收率为79.9%。化合物3与化合物4缩合生成N—[5-[N—[(3,4-二氢-2-甲基-4-氧-6-喹唑啉基)-甲基]-N-甲氨基]-2-噻吩甲酰基]-L-谷氨酸二乙酯(2),继而水解即得目标化合物雷替曲塞(1),总收率为22.5%。其结构经红外光谱、核磁共振谱、高分辨质谱及元素分析确证。 相似文献
167.
为了对大肠杆菌中由aroG基因编码的3-脱氧-D-阿拉伯庚酮糖酸-7-磷酸合成酶(DAHP合成酶)进行结构与功能的深入研究,尝试了aroG基因在枯草杆菌中的表达。表达载体以pUB110为骨架,采用了枯草杆菌热激蛋白groESL基因的启动子,碱性蛋白酶subtilisin基因的信号肽和N-乙酰胞壁酸-L-丙氨酸酰胺酶cwlHB基因的转录终止子,将aroG基因在枯草杆菌WB600宿主菌中进行了分泌表达 相似文献
168.
克隆并测定了暗纹东方鲍(Takifugu fasciatus)线粒体ATP合酶Fo亚基8(ATPase8)和亚基6(ATPase6)的序列,并对其进行了初步分析。结果表明:PCR扩增产物的总长度为923bp,其中842bp为ATP8和ATP6基因的编码区。ATP8基因长168bp,编码55个氨基酸残基的蛋白质,其蛋白分子质量为6.8KD,等电点为7.85;ATP6基因长684bp,编码227个氨基酸残基的蛋白质,其蛋白分子质量为24.9KD,等电点为9.16。暗纹东方纯ATP合酶Fo亚基8和亚基6与其他已报道的部分东方纯属鱼类具有很高的同源性。通过探讨ATP合酶F0亚基所含的信息量,发现相对于其他线粒体基因,ATPase8和ATPase6基因所含鉴别信息较少。 相似文献
169.
van den Heuvel RH Curti B Vanoni MA Mattevi A 《Cellular and molecular life sciences : CMLS》2004,61(6):669-681
Glutamate synthase is a multicomponent iron-sulfur flavoprotein belonging to the class of N-terminal nucleophile amidotransferases. It catalyzes the conversion of L-glutamine and 2-oxoglutarate into two molecules of L-glutamate. In recent years the X-ray structures of the ferredoxin-dependent glutamate synthase and of the a subunit of the NADPH-dependent glutamate synthase have become available. Thanks to X-ray crystallography, it is now known that the ammonia reaction intermediate is transferred via an intramolecular tunnel from the amidotransferase domain to the synthase domain over a distance of about 32Å. Although ammonia channeling is a recurrent theme for N-terminal nucleophile and triad-type amidotransferases, the molecular mechanisms of ammonia transfer and its control are different for each known amidotransferase. This review focuses on the intriguing mechanism of action and self-regulation of glutamate synthase with a special focus on the structural data.Received 8 August 2003; received after revision 15 September 2003; accepted 17 September 2003 相似文献
170.
Salchner P Lubec G Engelmann M Orlando GF Wolf G Sartori SB Hoeger H Singewald N 《Cellular and molecular life sciences : CMLS》2004,61(12):1498-1506
To identify neuronal substrates involved in NO/stress interactions we used Fos expression as a marker and examined the pattern of neuronal activation in response to swim stress in nNOS knock-out (nNOS–/–) and wild-type (WT) mice. Forced swimming enhanced Fos expression in WT and nNOS–/– mice in several brain regions, including cortical, limbic and hypothalamic regions. Differences in the Fos response between the two groups were observed in a limited set (6 out of 42) of these brain areas only: nNOS–/– mice displayed increased stressor-induced Fos expression in the medial amygdala, periventricular hypothalamic nucleus, supraoptic nucleus, CA1 field of the hippocampus, dentate gyrus and infralimbic cortex. No differences were observed in regions including the septum, central amygdala, periaqueductal grey and locus coeruleus. During forced swimming, nNOS–/– mice displayed reduced immobility duration, while no differences in general locomotor activity were observed between the groups in the home cage and during the open field test. The findings indicate that deletion of nNOS alters stress-coping ability during forced swimming and leads to an altered pattern of neuronal activation in response to this stressor in specific parts of the limbic system, hypothalamus and the medial prefrontal cortex.Received 29 March 2004; accepted 21 April 2004 相似文献