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1.
Treatment of Nicotiana glutinosa L. cell suspension cultures with chitosan results in the co-induction of phenylalanine ammonia lyase, 4-eoumarate:CoA ligase, tyrosine decarboxylase and tyramine hydroxycinnamoyltransferase, all involved in the biosynthesis of hydroxycinnamoyltyramines. The highest enzyme activities were observed around 12 h after addition of 0.8 to 1 mg chitosan per g fresh weight of cells. No hydroxycinnamoyltyramines could be detected by TLC or HPLC of extracts made from non-treated or elicited cells. [14C]-Tyramine was incorporated into insoluble polymeric material at a higher rate in elicitor-treated than in non-treated cells of N. glutinosa. Tyramine hydroxycinnamoyltransferase could be induced in suspension cultured cells of Eschscholtzia califortnca Cham, but not in cells of Phaseolus vulgaris L. or Catharanthus roseus (L.) G. Don by addition of a yeast elicitor to the growth medium.  相似文献   
2.
目的:本研究以模式小鼠C57BL为对象,研究小鼠在衰老过程中不同组织器官内源性亚精胺含量的变化。方法:利用高效液相色谱检测小鼠心脏和肝脏组织中亚精胺含量,进一步应用qRT-PCR以及Western blot检测在衰老过程中,不同组织器官中亚精胺生物合成途径的关键基因表达变化,利用亚精胺处理细胞检测DNA损伤应答能力。结果:随着衰老的发生心脏(199.09±17.12)和肝脏组织(168.92±5.12)中亚精胺含量显著降低,分别为78.01±13.52、62.05±6.73,差异有统计学意义(P0.05);不同组织器官中亚精胺生物合成途径的关键基因Odc、Srm、Amd1的表达随衰老的发生明显下调,并且伴随着DNA损伤应答障碍;利用亚精胺处理细胞,能够增强细胞对DNA损伤的应答反应。结论:衰老的小鼠中内源性亚精胺含量降低,并且其合成途径的关键基因转录水平降低,导致细胞对DNA损伤应答能力减弱,从而加速机体衰老进程。  相似文献   
3.
Pectinlyase complexes of Penicillium adametzii, P. citrinum and P. janthinellum occur as multiple molecular forms distinguished by their biosynthetic control. AMP is involved in derepression of pectinlyase formation.The authors are with the Institute of Microbiology, Belarus Academy of Sciences, Zhodinskaya 2, 220141, Minsk, Republic of Belarus.  相似文献   
4.
Plant hormones are signal molecules, present in trace quantities, that act as major regulators of plant growth and development. They are involved in a wide range of processes such as elongation, flowering, root formation and vascular differentiation. For many years, agriculturists have applied hormones to their crops to either increase the yield, or improve the quality of the commercial product. Nowadays, the knowledge of hormone biosynthesis, degradation and signaling pathways has allowed the utilization of biotechnological tools to further improve the main agricultural crops. Natural or artificial mutants, with impaired functioning of the corresponding genes, have been adopted because of their superior phenotype in specific agricultural traits. In addition, transgenic plants have been generated to regulate internal hormone levels, or their signaling pathways, resulting in some crops that have revolutionized agriculture.  相似文献   
5.
The biosynthesis of chlorophyll, an essential cofactor for photosynthesis, requires the ATP-dependent insertion of Mg2+ into protoporphyrin IX catalyzed by the multisubunit enzyme magnesium chelatase. This enzyme complex consists of the I subunit, an ATPase that forms a complex with the D subunit, and an H subunit that binds both the protoporphyrin substrate and the magnesium protoporphyrin product. In this study we used electron microscopy and small-angle x-ray scattering to investigate the structure of the magnesium chelatase H subunit, ChlH, from the thermophilic cyanobacterium Thermosynechococcus elongatus. Single particle reconstruction of negatively stained apo-ChlH and Chl-porphyrin proteins was used to reconstitute three-dimensional structures to a resolution of ∼30 Å. ChlH is a large, 148-kDa protein of 1326 residues, forming a cage-like assembly comprising the majority of the structure, attached to a globular N-terminal domain of ∼16 kDa by a narrow linker region. This N-terminal domain is adjacent to a 5 nm-diameter opening in the structure that allows access to a cavity. Small-angle x-ray scattering analysis of ChlH, performed on soluble, catalytically active ChlH, verifies the presence of two domains and their relative sizes. Our results provide a basis for the multiple regulatory and catalytic functions of ChlH of oxygenic photosynthetic organisms and for a chaperoning function that sequesters the enzyme-bound magnesium protoporphyrin product prior to its delivery to the next enzyme in the chlorophyll biosynthetic pathway, magnesium protoporphyrin methyltransferase.  相似文献   
6.
The production of the blue pigment indigoidine has been achieved in the entomopathogenic bacterium Photorhabdus luminescens by a promoter exchange and in Escherichia coli following heterologous expression of the biosynthesis gene indC. Moreover, genes involved in the regulation of this previously “silent” biosynthesis gene cluster have been identified in P. luminescens.  相似文献   
7.
抗生素AGPM生物合成途径的初步研究   总被引:5,自引:0,他引:5  
采用前体添加实验法、静息细胞培养法以及酶抑制剂法对藤黄灰链霉菌中抗生素AG PM生物合成途径进行了初步探讨。研究表明能转化成聚酮合成所需活性前体的氨基酸如异亮氨酸、缬氨酸、蛋氨酸、谷氨酸等以及短链脂肪酸乙酸、丙酸、丁酸盐对抗生素AGPM合成均有明显促进作用 ;另外 ,在培养基中添加脂肪酸和聚酮生物合成途径的专一性抑制剂浅蓝菌素 (2 5μg mL)或脂肪酸合成抑制剂碘乙酰胺 (0 5mmol L)时 ,菌体生长不受影响 ,而抗生素AGPM合成受到强烈抑制 ,分别为对照的 35 3 %和 2 6 2 % ;  相似文献   
8.
玉米赤霉烯酮生物合成和降解的研究进展   总被引:1,自引:0,他引:1  
介绍了玉米赤霉烯酮及其6个衍生物的分子结构,以及玉米赤霉烯酮的生物合成途径。阐述了玉米赤霉烯酮生物合成的基因序列群以及基因簇的表达方式。论述了玉米赤霉烯酮钝化和降解过程, 探讨了玉米赤霉烯酮水解酶在基因工程中的应用研究, 并为今后玉米赤霉烯酮生物工程降解研究提出了建议。  相似文献   
9.
茉莉酸作用的分子生物学研究   总被引:27,自引:3,他引:24  
吴劲松  种康 《植物学通报》2002,19(2):164-170
茉莉酸及其衍生物茉莉酸甲酯等统称为茉莉酸盐,是广泛存在于植物中的一种生长调节物质,在植物细胞中起着非常重要的作用,介绍了茉莉酸生物合成过程中关键酶基因的克隆、表达及调控,并对茉莉酸的一些突变体进行了分析,结果显示茉莉酸在发育及防御尤其是在雄性不育及抗病虫害方面起着非常重要的作用,同时综述了茉莉酸信号转导的最新成果。  相似文献   
10.
The extraction, purification and structural characterization of two lipid A precursors (Ia and Ib) differing only in one hexadecanoic acid are described. Both precursors were synthesized at elevated temperatures by a new mutant of Salmonella typhimurium (mutant Ts5) which is conditionally defective in synthesis of the 3-deoxy-d-manno-octulosonic acid region of lipopolysaccharides.Both precursors were purified by repeated phenol/chloroform/petroleum ether (PCP) extractions followed by thin layer chromatography. Teh precursor preparation was free of lipopolysaccharides and phospholipids and contained less than 0.1% protein. Structural analysis which included chemical degradation procedures as well as positive ion laser desorption (LDMS) mass spectroscopy of dephosphorylated lipid A precursors showed together that precursor Ia represents a diphosphorylated glucosamine disaccharide containing two ester, two amide-linked residues of 3-hydroxytetradecanoic acid and lacks the ester-linked dodecanoic, tetradecanoic and hexadecanoic acid as well as 3-deoxy-d-manno-octulosonic acid. Precursor Ib has the same basic structure as precursor Ia, but contains in addition one mol of hexadecanoic acid per mol disaccharide which is linked to the 3-hydroxy group of the amide-bound 3-hydroxy-tetradecanoic acid of the reducing, terminal glucosamine residue.The structure of precursor Ib supports the conclusion that hexadecanoic acid incorporation occurs at an early stage in lipid A biosynthesis prior to the attachment of 3-deoxy-d-manno-octulosonic acid and/or other polar substituents.Abbreviations LDMS laser desorption mass spectrometry - KDO 3-Deoxy-d-manno-octulosonic acid - Ts5 Salmonella typhimurium mutant Ts5 - PCP phenol/chloroform/petroleum ether - H2F2 hydrogen fluoride This work is dedicated to Prof. Dr. Drews, Freiburg, on the occasion of his 60th birthday  相似文献   
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