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71.
72.
Stability and ferrous iron content of the nitrogenase and its components from Azotobacter vinelandii
Summary Nitrogenase of Azotobacter vinelandii is sensitive to oxygen, and sensitivity develops during purification. Such inactivation is well prevented by 0.1% hydroquinone plus 0.01% ascorbate, which are also effective in preventing inactivation of enzyme on storage under H2. Activity is proportional to ferrous iron content of crude sample of enzyme. On storage at 0°C, 0.3 M KCl inactivates the enzyme, while KCl stabilizes its components. Nitrogenase is not cold labile, while the components are cold labile; Fe, Mo-component is most stable at 22°C and Fe-component at 13.5°C. Nitrogenase substrates, except N2, stabilize nitrogenase, but not the components. 相似文献
73.
74.
Megumi Narukawa‐Nara Ayako Nakamura Ko Kikuzato Yusuke Kakei Akiko Sato Yuka Mitani Yumiko Yamasaki‐Kokudo Takahiro Ishii Ken‐ichiro Hayashi Tadao Asami Takehiko Ogura Shigeo Yoshida Shozo Fujioka Takashi Kamakura Tsutomu Kawatsu Masanori Tachikawa Kazuo Soeno Yukihisa Shimada 《The Plant journal : for cell and molecular biology》2016,87(3):245-257
We previously reported l ‐α‐aminooxy‐phenylpropionic acid (AOPP) to be an inhibitor of auxin biosynthesis, but its precise molecular target was not identified. In this study we found that AOPP targets TRYPTOPHAN AMINOTRANSFERASE of ARABIDOPSIS 1 (TAA1). We then synthesized 14 novel compounds derived from AOPP to study the structure–activity relationships of TAA1 inhibitors in vitro. The aminooxy and carboxy groups of the compounds were essential for inhibition of TAA1 in vitro. Docking simulation analysis revealed that the inhibitory activity of the compounds was correlated with their binding energy with TAA1. These active compounds reduced the endogenous indole‐3‐acetic acid (IAA) content upon application to Arabidopsis seedlings. Among the compounds, we selected 2‐(aminooxy)‐3‐(naphthalen‐2‐yl)propanoic acid (KOK1169/AONP) and analyzed its activities in vitro and in vivo. Arabidopsis seedlings treated with KOK1169 showed typical auxin‐deficient phenotypes, which were reversed by exogenous IAA. In vitro and in vivo experiments indicated that KOK1169 is more specific for TAA1 than other enzymes, such as phenylalanine ammonia‐lyase. We further tested 41 novel compounds with aminooxy and carboxy groups to which we added protection groups to increase their calculated hydrophobicity. Most of these compounds decreased the endogenous auxin level to a greater degree than the original compounds, and resulted in a maximum reduction of about 90% in the endogenous IAA level in Arabidopsis seedlings. We conclude that the newly developed compounds constitute a class of inhibitors of TAA1. We designated them ‘pyruvamine’. 相似文献
75.
Suguru Takatsuto Nahoko Kosuga Bun-ichi Abe Takahiro Noguchi Shozo Fujioka Takao Yokota 《Journal of plant research》1999,112(1):27-33
Triticum aestivum L.) and foxtail millet (Setaria italica Beauv.) were found by GC-MS to contain, in addition to bulk sterols, 4-en-3-one steroids including 24-ethylcholesta-4,24(28)Z- dien-3-one (a new steroid), 24-methylcholest-4-en-3-one, 24-ethylcholesta-4,22E-dien-3-one and 24-ethylcholest-4-en-3-one, as well as 5α-steroidal 3-one compounds including 24-methyl-5α-cholestan-3-one,
24-ethyl-5α-cholestan-3-one and 24-ethyl 5α-cholest-22E-en-3-one (in S. italica only). Analysis of free sterol and steryl ester fractions indicated that campestanol and sitostanol were present at high
levels in both seeds. These results suggest that the seeds of T. aestivum and S. italica synthesize campestanol from campesterol via 24-methylcholest-4-en-3-one and 24-methyl-5α-cholestan-3-one as has already been
demonstrated in Arabidopsis thaliana L., and also produce sitostanol from sitosterol via 24-ethylcholest-4-en-3-one and 24-ethyl-5α-chotestan-3-one. Biosynthetic
relationships of campestanol and sitostanol with C28 and C29 brassinosteroids are discussed.
Received 4 September 1998/ Accepted in revised form 26 November 1998 相似文献
76.
77.
Molecular basis of spectral tuning in the red- and green-sensitive (M/LWS) pigments in vertebrates 总被引:3,自引:0,他引:3
Vertebrate vision is mediated by five groups of visual pigments, each absorbing a specific wavelength of light between ultraviolet and red. Despite extensive mutagenesis analyses, the mechanisms by which contemporary pigments absorb variable wavelengths of light are poorly understood. We show that the molecular basis of the spectral tuning of contemporary visual pigments can be illuminated only by mutagenesis analyses using ancestral pigments. Following this new principle, we derive the "five-sites" rule that explains the absorption spectra of red and green (M/LWS) pigments that range from 510 to 560 nm. Our findings demonstrate that the evolutionary method should be used in elucidating the mechanisms of spectral tuning of four other pigment groups and, for that matter, functional differentiations of any other proteins. 相似文献
78.
The estimated population of the Tsushima leopard cat Prionailurus bengalensis euptilura is only 80–110 individuals. However, the cause of the population decline is not clear. We investigated temporal changes in
the food habits of the cat and two other species of Carnivora (marten and weasel) inhabiting the Tsushima Islands by measuring
δ13C and δ15N values in hair samples. Hair samples of the cat were collected not only from specimens and furs, but also from feces. The
gathering of hair from cat feces was most efficient when the feces were collected in the spring. The food habit of male cats
seemed to be more diverse and tended to comprise prey of higher trophic levels than the food habits of the females. The δ13C and δ15N measurements suggested that the trophic level of the food sources has been decreasing over the last several decades for
the cat and weasel, but not for the marten. Increased consumption of prey from lower trophic levels in the food habit of the
cat seems to be related to the decline of the cat population because these phenomena occurred simultaneously. 相似文献
79.
Yuzuru Yamazoe Masanobu Tsubaki Hiroshi Matsuoka Takao Satou Tatsuki Itoh Takashi Kusunoki Yasuhiro Kidera Yoshihiro Tanimori Kaori Shoji Haruyuki Nakamura Mitsuhiko Ogaki Saori Nishiura Shozo Nishida 《Cell biology international》2009,33(10):1087-1094
NF-κB acts as a signal transducer during tumor progression, cell invasion, and metastasis. Dimethylfumarate (DMF) is reported to inhibit tumor necrosis factor-α-induced nuclear entry of NF-κB/p65. However, only a few reports suggest that DMF inhibits tumor metastasis; also the molecular mechanisms underlying the inhibition of metastasis are poorly understood. We investigated the inhibition of tumor invasion and metastasis by DMF in a melanoma cell line, B16BL6. DMF inhibited B16BL6 cell invasion and metastasis by suppressing the expression and activities of MMPs. DMF also inhibited the nuclear entry of NF-κB/p65, thus inhibiting B16BL6 cell invasion and metastasis. These results suggest that DMF is potentially useful as an anti-metastatic agent for the treatment of malignant melanoma. 相似文献
80.
Prostaglandin E2 is one of the major cyclooxygenase metabolites of arachidonic acid. We developed a competitive immunosorbent assay for prostaglandin E2 utilizing a bioluminescent enzyme Cypridina luciferase. The prostaglandin E2 amount could be quantified over the concentration ranging from 7.8 to 500 pg/mL. The amount of unlabeled prostaglandin E2 required to displace 50% of the maximal binding of Cypridina luciferase‐labeled prostaglandin E2 (B/B0) was approximately 35 pg/mL. The results show a great potential of Cypridina luciferase as a new labeling enzyme for enzyme‐linked immunosorbent assay. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献