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31.
H Shimoi T Kawahara K Suzuki Y Iwasaki A Y Jeng Y Nishikawa 《European journal of biochemistry》1992,209(1):189-194
The C-terminal amide structure of peptide hormones and neurotransmitters is synthesized via a two-step reaction catalyzed by peptidylglycine alpha-hydroxylating monooxygenase (PHM) and peptidylhydroxyglycine N-C lyase. A Xenopus laevis PHM expressed in insect-cell culture by the baculovirus-expression-vector system was purified to homogeneity and characterized. Using a newly established assay system for PHM, the kinetic features of this enzyme were investigated. As expected, the enzyme required copper ions, L-ascorbate and molecular oxygen for turnover. Salts like KI and KCl, and catalase stabilized the enzyme in the presence of L-ascorbate. The optimum pH value for the enzyme reaction was around six when Mes buffer was used and around seven when phosphate buffer was used under the same assay condition. Below pH 6, acetate, iodide and chloride ions activated the reaction. The kinetic analysis is consistent with a ping-pong mechanism with respect to peptide and L-ascorbate, and the peptide showed substrate inhibition. The substrate specificity of the enzyme at the penultimate position was examined by competitive assay using tripeptides with glycine at the C-termini and the inhibitory potency of these peptides in descending order was methionine > aromatic > non-polar amino acids. 相似文献
32.
Mechanisms of somatic embryogenesis in cell cultures: Physiology,biochemistry, and molecular biology
A. Komamine R. Kawahara M. Matsumoto S. Sunabori T. Toya A. Fujiwara M. Tsukahara J. Smith M. Ito H. Fukuda K. Nomura T. Fujimura 《In vitro cellular & developmental biology. Plant》1992,28(1):11-14
Summary One of the most characteristic cell functions in plants is totipotency. Somatic embryogenesis can be regarded as a model system
for the investigation of mechanisms of totipotency, because a high frequency and synchronous embryogenic system from single
somatic cells has been established in carrot suspension cultures. Four phases are recognized in this process, and several
molecular markers, viz. polypeptides, mRNAs, antigens against monoclonal antibodies, can be detected during the expression
of totipotency, but they disappear during its loss. Four organ-specific genes have been isolated from hypocotyls and roots
by differential screening. They were expressed preferentially after the globular-heart stages of embryogenesis, and were strongly
suppressed by auxin. A CEM 1 gene was isolated by differential screening of embryogenic cell clusters. This gene was expressed
strongly and transiently during the proglobular and globular stages. The sequence of CEM 1 was found to encode a polypeptide
showing high homology to the elongation factor isolated from eucaryotic cells. Thus good progress is being made in understanding
the basic mechanisms of somatic embryogenesis.
Presented in the Session-in-Depth Developmental Biology of Embryogenesis at the 1991 World Congress on Cell and Tissue Culture,
Anaheim, California, June 16–20, 1991. 相似文献
33.
Y Takai A Kishimoto Y Iwasa Y Kawahara T Mori Y Nishizuka A Tamura T Fujii 《Journal of biochemistry》1979,86(2):575-578
A new multifunctional protein kinase, which normally exists as an inactive form in the soluble fraction in mammalian tissues, attaches to membranes to exhibit full enzymatic activity. A low concentration of Ca2+ is absolutely necessary for this activation. This process is reversible. cAMP shows no effect. The active factors in membranes are phosphatidylinositol, phosphatidylserine, phosphatidic acid, diphosphatidylglycerol, and phosphatidylethanolamine in that order. Phosphatidylcholine and sphingomyelin are far less effective. Cytoplasmic as well as other membrane fractions from various tissues are active in supporting the enzymatic activity. A possible role of this Ca2+ and phospholipid-activated protein kinase system in transmembrane control is proposed. 相似文献
34.
Yoshio Kawahara Tsuyoshi Ohsumi Yasuhiko Yoshihara Shigeho Ikeda 《Bioscience, biotechnology, and biochemistry》2013,77(9):2475-2479
Osmoregulation in Brevibacterium lactofermentum was studied. Proline was accumulated up to approximately 35mg/g dry cell weight in the cells of a wild strain of the bacterium grown under osmotic stress. The osmotic tolerance of a proline auxotroph mutant obtained from the bacterium was lower than that in the wild strain. The activity of pyrroline-5-carboxylate reductase, one of the enzymes in the proline biosynthetic pathway, increased about 3-fold when the cells of B. lactofermentum were grown under osmotic stress. These data indicated that proline is important in osmoregulation in the bacterium. 相似文献
35.
Kazuki Yuzuriha Ayaka Yoshida Shunyi Li Akihiro Kishimura Takeshi Mori Yoshiki Katayama 《Journal of peptide science》2020,26(10)
In this report, we designed conjugates of an antigen peptide with the immunosuppressive vitamins all‐trans retinoic acid (ATRA) and vitamin D3 for efficient induction of antigen‐specific immunotolerance. We established a synthetic scheme for the preparation of the peptide‐vitamin conjugates, which the chemically unstable vitamins tolerated. Among the obtained conjugates, the ATRA conjugate successfully suppressed inflammatory effects in macrophages and dendritic cells and induced antigen presentation in dendritic cells. This synthetic method of conjugate is conceivably applicable to other antigen peptides for induction of antigen‐specific immunotolerance. 相似文献
36.
Miyuki Kusajima Moeka Fujita Hiromoto Yamakawa Tsukasa Ushiwatari Takamasa Mori Kazuki Tsukamoto 《Bioscience, biotechnology, and biochemistry》2020,84(7):1427-1435
ABSTRACT A newly identified chemical, 4-{3-[(3,5-dichloro-2-hydroxybenzylidene)amino]propyl}-4,5-dihydro-1H-pyrazol-5-one (BAPP) was characterized as a plant immunity activator. BAPP enhanced disease resistance in rice against rice blast disease and expression of a defense-related gene without growth inhibition. Moreover, BAPP was able to enhance disease resistance in dicotyledonous tomato and Arabidopsis plants against bacterial pathogen without growth inhibition, suggesting that BAPP could be a candidate as an effective plant activator. Analysis using Arabidopsis sid2-1 and npr1-2 mutants suggested that BAPP induced systemic acquired resistance (SAR) by stimulating between salicylic acid biosynthesis and NPR1, the SA receptor protein, in the SAR signaling pathway. 相似文献
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