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排序方式: 共有517条查询结果,搜索用时 218 毫秒
1.
T Kakizono T Nihira H Taguchi 《Biochemical and biophysical research communications》1986,137(3):964-969
Tryptophanase has an essential tyrosyl residue/active site which can be modified by tetranitromethane. Pyridoxal 5'-phosphate can prevent this modification efficiently, whereas pyridoxal 5'-phosphate N-oxide cannot, indicating that the free pyridinium N is required for the interaction of the coenzyme with the tyrosyl residue, probably via a hydrogen bond. The weakened binding of the coenzyme to the modified enzyme was confirmed on gel filtration, the modified enzyme being dissociated from the coenzyme seven-fold faster than the native enzyme. Furthermore, absorption spectral analyses demonstrated that the modified enzyme can catalyze the transaldimination step, but fails to abstract the alpha-H of substrates. The tyrosyl residue, therefore, not only participates in coenzyme binding, but also contributes to alpha-H labilization. 相似文献
2.
3.
Tatsuo Nakahara Makoto Hirano Takashi Matsumoto Toshihide Kuroki Yoshinori Tatebayashi Tetsuyuki Tsutsumi Kouji Nishiyama Hiroaki Ooboshi Kaoru Nakamura Hiroshi Yao Akio Shiraishi Michinori Waki Hideyuki Uchimura 《Neurochemical research》1990,15(6):609-611
DNA and RNA contents in 20 brain regions or nuclei of the rat were determined by a highly sensitive method using high-performance liquid chromatography with electrochemical detection. The high DNA and RNA contents were found in the hypothalamic nuclei, especially the median eminence-arcuate nucleus. These results may be available for the preparation of nucleic acids as the regional control. 相似文献
4.
Satoru Furukawa Akio Ozaki Yukinobu Kotani Toshihide Nakanishi 《Applied microbiology and biotechnology》1988,29(2-3):253-257
Summary
l-Threonine hyper-producing mutants were obtained fromEscherichia coli W strain KY-8366, by reducingl-threonine degradation activity and enhancingl-threonine biosynthetic activity. Anl-threonine degradation reaction test using resting cells of KY-8366 suggested that the main pathway ofl-threonine degradation by KY-8366 is via glycine. A strain with reducedl-threonine degradation activity was obtained among those mutants that could not utilizel-threonine as sole nitrogen source. Rifampicin-resistant mutants andl-lysine plus methionine-insentitive mutants were isolated. These mutants showed enhanced aspartokinase levels and accumulated morel-threonine than the parental strains. Mutant H-4290 accumulated 58 g/l ofl-threonine. 相似文献
5.
Satoru Furukawa Akio Ozaki Toshihide Nakanishi 《Applied microbiology and biotechnology》1988,29(6):550-553
Summary Growth and l-threonine productivity of l-threonine producer Escherichia coli H-4290 were inhibited by precursor amino acids, l-homoserine and l-aspartate. l-Threonine hyper-producers were isolated among the mutants resistant to l-homoserine and l-aspartate. Mutants H-4351 (Homr) and H-4578 (Homr, Aspr) accumulated 22.2 g/l and 24.3 g/l of l-threonine in test tube cultures, while the parental strain H-4290 accumulated 18.2 g/l. The enzyme level of aspartokinase I (first enzyme of the threonine operon) was enhanced 2.3 times (H-4351) and 3 times (H-4578) that of H-4290. Mutant H-4578 accumulated 76 g/l of l-threonine in a 2-l jar fermentor after 75 h cultivation.Abbreviations DAP
diaminopimeric acid
- Met
l
poor growth in methionine-free medium
- AHV
-amino--hydroxyvaleric acid
- Thr-N-
lack of ability to utilize l-threonine as a nitrogen source
- Rif
rifampicin
- Lys+Metr
resistant to l-lysine and dl-methionine 相似文献
6.
7.
The reaction to C-banding was investigated throughout the mitotic cycle ofCrepis capillaris (2n=6): (1) 18–22 C-bodies or C-bands were found during mid telophase and interphase to prophase and metaphase, and also
12–14 at late anaphase to early telophase in the mitotic cycle. Fewer C-bands in late anaphase to early telophase were due
to the absence of minute bands; (2) large and medium sized C-bands were strongly stained by Giemsa, while small and minute
bands stained palely. It is suggested that inCrepis capillaris the difference of color in C-banded segments following Giemsa staining is referable to the amount of constitutive heterochromatin
rather than to the difference in the condensation and decondensation; (3) the size of C-bodies changed during telophase to
interphase and prophase. It is inferred that the extent of C-bodies is regulated by both the length of DNA sequences of constitutive
heterochromatin and the amount of proteins combined with C-banded DNA. It was shown that the reaction to C-banding is neither
due to the differential condensation of chromatin nor to a higher concentration of DNA in the C-banded regions, in the C-banding
mechanism as has been suggested so far at least. 相似文献
8.
Distribution of Glycinebetaine in Old and Young Leaf Blades of Salt-Stressed Barley Plants 总被引:4,自引:0,他引:4
Nakamura Toshihide; Ishitani Manabu; Harinasut Poontariga; Nomura Mika; Takabe Teruhiro; Takabe Tetsuko 《Plant & cell physiology》1996,37(6):873-877
In barley plants exposed to stepwise salt-stress (up to 200mM NaCl), sodium and chloride ions accumulated preferentiallyin old rather than in young leaf blades. Furthermore, the levelof glycinebetaine in young leaf blades was approximately threetimes that in old leaf blades.
3Present address: Department of Biochemistry, Faculty of Science,Kasesart University, Bangkok, 10900 Thailand 相似文献
9.
Philip D. Fernsten Jan K. Czyzyk Toshihide Mimura John B. Winfield 《Molecular biology reports》1994,20(2):85-95
Patients with SLE develop IgM autoantibodies to different isoforms of CD45, the major surface membrane protein tyrosine phosphatase on lymphocytes and other nucleated hemopoietic cells. Because such autoantibodies could have a potential role in the development of immune dysfunction in this disorder, we performed a series of experiments to characterize their antigenic specificity further. Blots of recombinantE. coli fusion proteins encoded by exons 3–7 of the p220 and p180 isoforms were uniformly non-reactive with SLE IgM, suggesting that anti-CD45 autoantibodies in SLE are directed against conformational and/or carbohydrate epitopes, rather than linear polypeptide epitopes. This issue was examined further using chemically and enzymatically modified CD45 purified from T cells by lectin affinity chromatography as substrates. Treatment of CD45 with 25 mM sodium-m-periodate, sufficient to abrogate binding to various lectins, abolished the reactivity with SLE anti-CD45 autoantibodies. On the other hand, digestion of CD45 with neuraminidase enhanced the binding of anti-CD45 autoantibodies from some of the SLE sera. This result probably reflects decreased steric hindrance or charge repulsion because the binding of mouse monoclonal antibodies directed against linear polypeptide epitopes of CD45 was similarly enhanced. Digestion of CD45 with N-glycosidase F had no effect on autoantibody staining. Taken together, these data suggest that IgM anti-CD45 autoantibodies in SLE recognize non-sialylated carbohydrate determinants in the highly O-glycosylated polymorphic domains of CD45.Abbreviations SLE
systemic lupus erythematosus
- SBA
soybean agglutinin
- RCAI
Ricinus communis agglutinin
- SNL
Sambucus nigra lectin
- MBP
maltose binding protein
- mAb
monoclonal antibody
- WGA
wheat germ agglutinin 相似文献
10.