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61.
X-ray diffraction studies of enkephalins. Crystal structure of [(4''-bromo) Phe4,Leu5]enkephalin. 总被引:3,自引:1,他引:2 下载免费PDF全文
T Ishida M Kenmotsu Y Mino M Inoue T Fujiwara K Tomita T Kimura S Sakakibara 《The Biochemical journal》1984,218(3):677-689
In order to investigate the structure-activity relationship of [Leu5]- and [Met5]enkephalins, [(4'-bromo)Phe4, Leu5]-, [(4'-bromo)Phe4, Met5]- and [Met5] enkephalins were synthesized and crystallized. The crystal structure of [(4'-bromo) Phe4, Leu5]- enkephalin was determined by X-ray diffraction method using the heavy atom method and refined to R = 0.092 by the least-squares method. The molecule in this crystal took essentially the same type I' beta-turn conformation found in [Leu5]enkephalin [Smith & Griffin (1978) Science 199, 1214-1216). On the other hand, the preliminary three-dimensional Patterson analyses showed that the most probable conformations of [(4'-bromo)Phe4,Met5]- and [Met5]enkephalins are both the dimeric extended forms. Based on these insights, the biologically active conformation of enkephalin was discussed in relation to the mu- and delta-receptors. 相似文献
62.
S. Takagi H. Sakata T. Yoshida K. Den T.K. Fujii H. Amemiya M. Tomita 《Prostaglandins & other lipid mediators》1978,15(5)
ONO-802 was used in the form of vaginal suppositories for the termination of early pregnancy in 63 healthy volunteers. Fifty-four (86%) of the 63 cases had complete abortions and remaining 9 (14%) had incomplete abortions.One (1.6%) of the 63 cases complained of nausea and vomiting, and 3 (4.8%) complained of headaches. No other side effects were observed.These results suggest that ONO-802 is acceptable in the form of vaginal suppositories for the termination of early pregnancy. 相似文献
63.
Noyes' scheme of the elementary processes for the Belousov-Zhabotinsky reaction has been simplified on the basis of reaction kinetic consideration. The simplest possible analogue (model K) has been described by a set of kinetic equations, and it is solved to examine the varieties of new ordered phases, which include temporal rhythm and spatial pattern. Particular attention has been given to the onset of new phases, which is associated with an anomalous enhancement of fluctuations. A stochastic theory of fluctuations, which was developed in our previous work, has been applied to the present case. Theoretical results compare reasonably well with experimental findings, i.e. with (1) spatial periodic structure and (2) limit cycle behaviour. 相似文献
64.
Summary The complete amino acid sequence of the major sialoglycoproteins of horse erythrocyte membranes, glycophorin HA, was determined by manual sequencing methods, using tryptic, chymotryptic, and cyanogen bromide fragments. Glycophorin HA is a polypeptide chain of 120 amino acid residues and contains 10 oligosaccharide units attached to the amino-terminal side of the molecule. Its amino terminus is pyroglutamic acid. All of the oligosaccharides are linked O-glycosidically to threonine or serine residues. The amino acid sequence is consistent with the transmembrane orientation of glycophorins.There is no significant homology between the glycosylated domains of horse, human, and porcine glycophorins, but there is a considerable homology between the hydrophobic domains of the three glycophorins, which interact with the lipid bilayer of the erythrocyte membrane. 相似文献
65.
Toshimasa Ishida Ken-Ichi Tomita Masatoshi Inoue 《Archives of biochemistry and biophysics》1980,200(2):492-502
The crystal and molecular structures of the title complex has been determined by X-ray diffraction methods, as a model for tryptophan residues in protein-pyridine coenzyme interactions. The structure was solved by direct methods and was refined by standard methods (final R = 0.073). The light-green crystals consist of alternate layers of indole-3-acetic acid and 1-methyl-3-carbamoylpyridinium molecules piled up to the c-direction, and are stabilized by the crystal water participating in hydrogen bonds in the a- and b-directions. The parallel stackings and interplanar spacing distances between indole and pyridinium rings strongly suggest a II–II1 charge transfer from the indole ring to the lowest unoccupied orbital of the pyridinium ring in the ground state. Furthermore, this crystal structure provides evidence that quaternization of the N1 position enhances electron-acceptor properties of pyridine. On the other hand, the proton magnetic resonance spectra suggest that the stacking mode between both rings in solution is very similar to the one observed in the crystal structure. 相似文献
66.
Quantitative study of the cytochrome c acting in the photosyntheticsystem of the blue-green alga Anabaena variabilis (M-2) wasdone with membrane fragments and intact cells. Membrane fragments highly active in the NADP+-Hill reaction(above 200 µmoles/mg chl.a;-hr) retained photoresponsivecytochrome c equal only one-tenth that of P700, while the plastocyanincontent was almost equal to that of P700. The cytochrome contentin intact cells was a little larger than that in membrane fragmentson the chlorophyll a basis. However, the values relative toP700 (1/9) and plastocyanin (1/10) were identical with thosein membrane fragments. The content was also far smaller thanthat of reaction center II's (1/6). If the cytochrome mediatesall electrons from reaction center II, the cytochrome oxidation-reductionshould have a rate constant of 2.4?102 sec1 which isone order above of the rate constant of the cytochrome reduction(2.3 to 3.5?101sec1). These quantitative relationshipsindicate that in Anabaena variabilis (M-2), c-type cytochrome,either cytochrome f or algal cytochrome c, cannot function inthe main electron flow between two reaction centers. (Received September 8, 1978; ) 相似文献
67.
In the search for the photoreceptor in photocontrolled phycoerythrinformation, photoreversible absorption changes of chromoproteinsin vivo and in vitro were studied with the blue-green alga Tolypothrixtenuis. Neither intact cells nor crude extracts of soluble proteinsshowed any significant absorption changes which were reversiblyinduced by green and red light. However, the photoresponse wasobservable when the crude protein extracts were treated withthe chaotropic reagent guanidine-HCl (0.4 M, for 1 hr in thedark). Isolated phycocyanin and allophycocyanin also showedthe same photoresponse after the guanidine-HCl treatment. Thedifference spectrum (green minus red) of guanidine-HCl-treatedphycocyanin was almost identical with that shown by phycochromea of Bj?rn and Bj?rn (3), and the allophycocyanin showed thesame difference spectrum as those of phycochrome c of Bj?rnand Bj?rn and the photoreversible pigment isolated by Scheibe(7). Urea at a concentration higher than 1 M or alkaline incubation(pH 8.5) also showed the same effect. The results were interpretedas indicating that phycocyanin and allophycocyanin obtain theability for photoresponsiveness when their protein conformation,probably around the chromophore site, is modified. (Received October 30, 1978; ) 相似文献
68.
Carotenoid photobleaching induced by photosystem II action wasstudied using membrane fragments of the blue-green alga Anabaenavariabilis. Special attention was paid to the action of O2. Carotenoid photobleaching elicited by carbonyl cyanide m-chlorophenylhydrazone(CCCP) depended on O2. However, the addition of H2O2, sodiumsilicotungstate or potassium ferricyanide (Ferri), an electronacceptor for reaction center II action, removed the O2-dependency.These results indicate that O2 acts as the electron acceptorfor this reaction. When both CGCP and Ferri were present, a short illumination(0.25 sec) caused a rapid photobleaching followed by a slowrecovery in the subsequent dark period. The spectrum of theabsorption decrease in the light was identical with that ofthe absorption increase in the subsequent dark, indicating thata reversible process is involved in the carotenoid photobleaching.The size in the dark recovery relative to the light bleachingbecame larger under anaerobic conditions and smaller under higherpartial pressure of O2. The reuslts were interpreted as indicatingthat O2 does not function in the primary process including areversible bleaching step, but is involved in the slow and irreversiblebleaching process. (Received April 3, 1978; ) 相似文献
69.
Yasuko Mizuno Atsushi Ichikawa Kenkichi Tomita 《Prostaglandins & other lipid mediators》1983,26(5):785-795
The effect of 7-fluoro proscyclilin (PGI2-F), a chemically stable analogue of prostacyclin, on cAMP accumulation in and [3H]PGE binding to mastocytoma P-815 cells was compared with those of the Na salt and methyl ester of prostacyclin (PGI2Na or PGI2Me), which are rapidly inactivated in aqueous solution or metabolized in the tissue.PGIF was as effective as PGI2Me, and slightly less effective than PGI2Na in stimulating cAMP accumulation in mastocytoma cells and rabbit platelets. PGI2F was also more stable than PGI2Me or PGI2Na, and retained its original cAMP elevating activity even after incubation with or without cells for 4 h at 37°C. Cells which had been exposed to PGI2F and then washed free of unbound reagent continued to produced cAMP for more than 3 h. PGI2F was also as effective as PGE1 or PGE2 in displacing [3H]PGE2 bound to the cells. Non-competitive inhibition by PGI2F or PGI2Me of [3H]PGE2 binding to the cells, with apparent Kis of 1.29 μM and 1.13 μM, respectively, indicates the presence of different receptors for PGE2 and for PGI2F or PGI2Me in mastocytoma P-815 cells. 相似文献
70.
U Tomita A Inanobe I Kobayashi K Takahashi M Ui T Katada 《Journal of biochemistry》1991,109(1):184-189
The effects of mastoparan and compound 48/80 on the activities of alpha beta gamma-trimeric GTP-binding proteins (G proteins) were studied with purified Go and Gi-1 which had been reconstituted into phospholipid vesicles. Pertussis toxin-catalyzed ADP-ribosylation of Go or Gi-1 was inhibited by mastoparan or compound 48/80, suggesting that the G proteins were dissociated into their constituent alpha- and beta gamma-subunits in the presence of these compounds. The steady-state rate of GTP hydrolysis catalyzed by Go or Gi-1 was stimulated by the two compounds. Both the stimulations were due to increases in the rate of the GDP-GTP exchange reaction occurring on the G proteins. However, the modes stimulation of the GTPase activity depended on the type of G protein used, and the stimulations caused by the two compounds were differently affected by pertussis toxin-catalyzed ADP-ribosylation of G proteins. Moreover, the mastoparan-induced stimulation of the GTPase activity was partially inhibited by compound 48/80. Thus, the two histamine secretagogues mastoparan and compound 48/80 appear to activate G proteins differently, though they interact with the signal-transducing proteins, at least partly, at a common binding site. 相似文献