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131.
Hitoshi Ashida Essam Enan Fumio Matsumura 《Journal of biochemical and molecular toxicology》1996,11(6):269-278
The effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on lipid peroxidation, 3H-Me-glucose (3H-Me-glu), and 14C-dehydroascorbic acid (14C-DHA) uptakes were studied in adipose tissue of male guinea pig. Under in vitro test conditions, using isolated adipose tissue in a culture medium (explant culture), TCDD reduced the uptake of 3H-Me-glu and 14C-DHA in a dose- and time-dependent fashion. The IC50 values of TCDD's action were 0.04 and 2 nM on 14C-DHA and 3H-Me-glu uptakes, respectively. TCDD (10 nM) also suppressed glucose transporting activity within 15 minutes in explant-cultured adipocytes. Cytochalasin B (CB) and nonlabeled D-glucose inhibited 14C-DHA uptake also in a dose-dependent manner. In addition, TCDD was found to induce lipid peroxidation in ex-plant-cultured adipose tissue. This effect of TCDD was similar to that of a typical lipid peroxidation inducer, CCl4, and it was dose and time dependent. TCDD caused a statistically significant rise in lipid peroxidation at a concentration as low as 0.1 nM after 60 minutes of treatment in explant culture. Unexpectedly, the Ah receptor partial antagonists, 4,7-phenanthroline and α-naphthoflavone, did not fully antagonize TCDD-induced lipid peroxidation in explant-cultured adipocytes. In vivo treatment of TCDD also induced lipid peroxidation. Among seven organs of male guinea pig tested, the levels of lipid peroxidation in adipose tissue and in liver increased at 1 and 40 days following a single i.p. dose of TCDD (1 μg/kg). The results of an in vivo time-course study indicated that such an effect of TCDD was most pronounced after 40 days of treatment. Finally, we have tested the protective role of some antioxidants on TCDD-induced lipid peroxidation under explant-culture conditions. The results indicated that DHA, but not ascorbic acid, could completely abolish TCDD-induced lipid peroxidation. The protective effect of DHA on TCDD-induced lipid peroxidation was stronger than that of α-tocopherol and uric acid, and this effect was blocked by CB. We conclude from these studies that TCDD acts in this guinea pig tissue through two different routes: one is the Ah receptor-dependent route causing the reduction of the level of glucose transporters and subsequent decrease of cellular uptake of DHA and the other, the Ah receptor-independent route causing the overall lipid peroxidation. Nevertheless, it appears likely that both events are antagonized by DHA. © 1997 John Wiley & Sons, Inc. J Biochem Toxicol 11: 269–278, 1997. 相似文献
132.
Kaori Tsukakoshi Yasuko Yamagishi Mana Kanazashi Kenta Nakama Daiki Oshikawa Nasa Savory Akimasa Matsugami Fumiaki Hayashi Jinhee Lee Taiki Saito Koji Sode Kanjana Khunathai Hitoshi Kuno Kazunori Ikebukuro 《Nucleic acids research》2021,49(11):6069
Aptamers can control the biological functions of enzymes, thereby facilitating the development of novel biosensors. While aptamers that inhibit catalytic reactions of enzymes were found and used as signal transducers to sense target molecules in biosensors, no aptamers that amplify enzymatic activity have been identified. In this study, we report G-quadruplex (G4)-forming DNA aptamers that upregulate the peroxidase activity in myoglobin specifically for luminol. Using in vitro selection, one G4-forming aptamer that enhanced chemiluminescence from luminol by myoglobin''s peroxidase activity was discovered. Through our strategy—in silico maturation, which is a genetic algorithm-aided sequence manipulation method, the enhancing activity of the aptamer was improved by introducing mutations to the aptamer sequences. The best aptamer conserved the parallel G4 property with over 300-times higher luminol chemiluminescence from peroxidase activity more than myoglobin alone at an optimal pH of 5.0. Furthermore, using hemin and hemin-binding aptamers, we demonstrated that the binding property of the G4 aptamers to heme in myoglobin might be necessary to exert the enhancing effect. Structure determination for one of the aptamers revealed a parallel-type G4 structure with propeller-like loops, which might be useful for a rational design of aptasensors utilizing the G4 aptamer-myoglobin pair. 相似文献
133.
Shimada H Kaname T Suzuki M Hitoshi Y Araki K Imaizumi T Yamamura K 《Molecular reproduction and development》1999,52(4):376-382
Markers and the means to detect them are required to monitor the fate of living cells. However, few suitable markers for living cells were known until a green fluorescent protein (GFP) was discovered. We have established mouse embryonic stem (ES) cell lines that express mutant GFP under the chicken beta-actin (CAG) promoter. Using these cell lines, we were able to follow the migration of ES cells during blastocyst formation both in sandwiching and coculture methods, even if only a single ES cell was used. Furthermore, the contribution of ES cells to the inner cell mass (ICM) was easily estimated at the blastocyst stage. We compared sandwiching with coculture aggregation relative to the contribution of the ES cell in the ICM, and the results indicated that there was no difference in the ratios of chimeric embryos having ICM contributed from cultured ES cells. Furthermore, an aggregated single ES cell was able to contribute three or four cells to the ICM at the blastocyst stage. Thus we conclude that one, instead of two, embryos is enough to make aggregation with ES cells, and a single ES cell attached to an embryo is enough to produce germline chimeras. Moreover, we could clearly observe single cell fate during blastocyst formation. This suggests that our established cell line can be used for monitoring single cell fate in vivo. In addition, we have shown that up to five doses of 30 sec of UV irradiation using GFP filters have no effect on the embryonic development. 相似文献
134.
Effects of the C132-methoxycarbonyl moiety on the self-assembly of chlorosomal chlorophylls (Chls) were studied. Model compounds, zinc methyl 3-devinyl-3-(1-hydroxymethyl)-pheophorbides a and a (Zn-31-OH-Chls a/a, C132-epimers) were synthesized from Chl a, and their aggregation behaviors were examined in Triton X-100 (TX-100) micellar suspensions and in 6%THF/water, in comparison with those of a pyrolized derivative, zinc methyl 3-devinyl-3-(1-hydroxymethyl)-132-demethoxycarbonyl-pheophorbide a (Zn-31-OH-pyroChl a). Zn-31-OH-Chl a formed self-aggregates in the TX-100 micellar suspension and gave a Qy absorption peak at 703 nm, while Zn-31-OH-pyroChl a aggregates of a Qy peak at 740 nm. In the Zn-31-OH-Chl a aggregate spectrum, the Qy red-shift was smaller, the band shape was broader, and the contribution of the residual monomer was more intense than that in the Zn-31-OH-pyroChl a aggregate spectrum. The bulky C132-moiety limits the ways of molecular association, and electronic interaction between the component molecules of the Zn-31-OH-Chl a aggregate is weakened. Stereoselective control of the aggregation of the C132-epimer was also examined. 相似文献
135.
Asadulghani Nitta K Kaneko Y Kojima K Fukuzawa H Kosaka H Nakamoto H 《Archives of microbiology》2004,182(6):487-497
136.
Structural and biochemical analyses of hemimethylated DNA binding by the SeqA protein 总被引:1,自引:1,他引:0
Fujikawa N Kurumizaka H Nureki O Tanaka Y Yamazoe M Hiraga S Yokoyama S 《Nucleic acids research》2004,32(1):82-92
The Escherichia coli SeqA protein recognizes the 11 hemimethylated G-mA-T-C sites in the oriC region of the chromosome, and prevents replication over-initiation within one cell cycle. The crystal structure of the SeqA C-terminal domain with hemimethylated DNA revealed the N6-methyladenine recognition mechanism; however, the mechanism of discrimination between the hemimethylated and fully methylated states has remained elusive. In the present study, we performed mutational analyses of hemimethylated G-mA-T-C sequences with the minimal DNA-binding domain of SeqA (SeqA71–181), and found that SeqA71–181 specifically binds to hemimethylated DNA containing a sequence with a mismatched mA:G base pair [G-mA(:G)-T-C] as efficiently as the normal hemimethylated G-mA(:T)-T-C sequence. We determined the crystal structures of SeqA71–181 complexed with the mismatched and normal hemimethylated DNAs at 2.5 and 3.0 Å resolutions, respectively, and found that the mismatched mA:G base pair and the normal mA:T base pair are recognized by SeqA in a similar manner. Furthermore, in both crystal structures, an electron density is present near the unmethylated adenine, which is only methylated in the fully methylated state. This electron density, which may be due to a water molecule or a metal ion, can exist in the hemimethylated state, but not in the fully methylated state, because of steric clash with the additional methyl group. 相似文献
137.
Ochiai I Matsuda K Nishi M Ozawa H Kawata M 《Molecular endocrinology (Baltimore, Md.)》2004,18(1):26-42
Androgen and estrogen act not only in a sex-specific manner but also interactively and synergistically. In the present study, to examine the possible interaction between androgen receptor (AR) and estrogen receptor-alpha (ERalpha), we investigated the subcellular dynamics of AR and ERalpha fused with green fluorescent protein color variants in single living cells using time-lapse microscopy and the technique of fluorescence recovery after photobleaching. AR and ERalpha showed punctate colocalization in the nucleus with estrogen, but not androgen. N-terminal AR deletion mutant did not form a nuclear punctate pattern with either androgen or estrogen. In the presence of AR, but not ERalpha, N-terminal AR deletion mutant formed a punctate nuclear pattern with androgen. AR had different mobility depending on the ligand and the presence of ERalpha. On the other hand, AR had little effect on the stability of ERalpha. ERalpha mutant that does not bind coactivators did not alter the mobility of AR. Taken together, using an imaging technique, we clarified that possible homo/hetero dimerization between AR and ERalpha could be attributed to androgen-estrogen interaction in living cells. 相似文献
138.
Hashimoto T Sano T Ito W Kanazawa K Danno G Ashida H 《Bioscience, biotechnology, and biochemistry》2004,68(4):964-967
A dietary carcinogen, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) at 20 microM activates caspase-3-like proteases as an apoptotic marker in rat splenocytes. The present study demonstrated 100 microM Trp-P-1 induced necrosis with activation of caspase-3-like proteases. The activation in necrosis and apoptosis resulted from the activation of caspase-9 and caspase-8, respectively. Thus, Trp-P-1 induces apoptosis and necrosis with the activation of different caspases. 相似文献
139.
Kumagai H Koizumi A Suda A Sato N Sakurai H Kumagai H 《Bioscience, biotechnology, and biochemistry》2004,68(7):1598-1600
Soybean globulins were deamidated after removing phytate using ion-exchange resins, and then hydrolyzed by digestive enzymes. The phytate-removed deamidated soybean globulins (PrDS) retained high calcium-binding ability even after the hydrolysis by digestive enzymes. PrDS and its hydrolysates enhanced calcium absorption from the small intestine when injected into the small intestine together with a calcium solution. 相似文献
140.