全文获取类型
收费全文 | 2245篇 |
免费 | 172篇 |
国内免费 | 1篇 |
出版年
2022年 | 16篇 |
2021年 | 30篇 |
2020年 | 15篇 |
2019年 | 12篇 |
2018年 | 24篇 |
2017年 | 26篇 |
2016年 | 44篇 |
2015年 | 59篇 |
2014年 | 83篇 |
2013年 | 122篇 |
2012年 | 143篇 |
2011年 | 137篇 |
2010年 | 92篇 |
2009年 | 89篇 |
2008年 | 115篇 |
2007年 | 141篇 |
2006年 | 128篇 |
2005年 | 118篇 |
2004年 | 115篇 |
2003年 | 115篇 |
2002年 | 107篇 |
2001年 | 50篇 |
2000年 | 43篇 |
1999年 | 56篇 |
1998年 | 22篇 |
1997年 | 32篇 |
1996年 | 32篇 |
1995年 | 23篇 |
1994年 | 25篇 |
1993年 | 16篇 |
1992年 | 38篇 |
1991年 | 33篇 |
1990年 | 40篇 |
1989年 | 31篇 |
1988年 | 31篇 |
1987年 | 29篇 |
1986年 | 30篇 |
1985年 | 22篇 |
1984年 | 16篇 |
1983年 | 16篇 |
1982年 | 22篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1979年 | 12篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 7篇 |
1973年 | 4篇 |
1968年 | 3篇 |
排序方式: 共有2418条查询结果,搜索用时 828 毫秒
21.
Summary The photoreceptors in the compound eye of a cabbage butterfly, Pieris rapae, were examined by conventional and intracellular-labeling electron microscopy by the use of the cobalt(III)-lysine complex as an ionized marker. Five types of spectral sensitivity were recorded intracellularly in electrophysiological experiments. They peaked at about 340, 380, 480, 560 and 620 nm, respectively. One of the distal retinula cells (R2) was a UV receptor, whereas the R4 distal retinula cell was a green receptor. The basal retinula cell, R9, was found to be a red receptor; it was localized near the basement membrane, having a bilobed cell body with an individual nucleus in each lobe. A small number of rhabdomere microvilli were present in a narrow cytoplasmic bridge connecting the two lobes. The axons of six retinula cells (R3–R8) in each ommatidium terminated at the cartridge in the lamina (short visual fiber), whereas those of the other three retinula cells, R1, R2 and R9, extended to the medulla (long visual fiber). The information from the UV and red receptors is therefore probably delivered directly to the medulla neurons, independent of that from the other spectral receptor types. 相似文献
22.
E Benedikt A Gossauer H P K?st W Miki K Yamaguchi 《European journal of biochemistry》1988,175(3):643-648
The ovaries of the marine snail Turbo cornutus contain a number of pigments. So far, the presence of carotenoids and a chromoprotein with a bile pigment, called turboverdin (= 3(2)-hydroxy-mesobiliverdin IX alpha), as its prosthetic group are known. The present work describes the isolation and structure elucidation of two further bile pigments, biliverdin IX delta and neobiliverdin IX delta. This is the first report of naturally occurring bile pigments with IX delta structure. 相似文献
23.
Theoretical analysis of a site-specific chemiluminescence reaction and its application to quantitation of lipid hydroperoxides 总被引:1,自引:0,他引:1
K Fukuzawa T Yoshimura T Fujii K Takauchi M Miki H Tamai M Mino 《Chemistry and physics of lipids》1988,48(3-4):197-203
A system was designed for chemiluminescent measurement of lipid hydroperoxides by their site-specific reaction in sodium dodecylsulfate micelles. Ferrous ion-induced decomposition of lipid hydroperoxides in the sodium dodecylsulfate micelles resulted in strong chemiluminescence of the Cypridina luciferin analog, 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-alpha]pyrazin-3-one (CLA). After addition of ferrous sulfate to the micelles containing lipid hydroperoxide and luciferin, the chemiluminescence intensity reached a maximum rapidly and then decreased. The sequence of this reaction was elucidated by theoretical analysis, which demonstrated that the maximum chemiluminescence intensity is proportional to the initial concentration of hydroperoxide. Good linear relationships were observed between the maximum counts of chemiluminescence and the amounts of hydroperoxides of linoleic acid, phosphatidylcholine, choresterol (5 alpha), cumene and tert-butyl and hydrogen peroxide. This chemiluminescence method was simple and sensitive enough to detect picomole levels of linoleic acid and phosphatidylcholine hydroperoxides. 相似文献
24.
Intramonomer fluorescence resonance energy transfer between the donor epsilon-ATP bound to the nucleotide site and the acceptor N-(4-dimethylamino-3,5-dinitrophenyl)maleimide (DDPM) or 4-dimethylaminophenyl-azophenyl-4'-maleimide bound to Cys-10 in G-actin was measured. The donor-acceptor distance was calculated to be about 40 A. The intermonomer energy transfer in F-actin occurring between epsilon-ADP and DABMI was also measured. The radial coordinate of Cys-10 was calculated to be 25 A based on the helical symmetry of F-actin and the recently calculated radial coordinate of the nucleotide binding site in F-actin i.e. 25 A (Miki, M., Hambly, B. and dos Remedios, C.G. (1986) Biochim. Biophys. Acta 871, 137-141). (The assumption has been made in calculating these distances that the energy donor and acceptor rotate rapidly relative to the fluorescence lifetime.) Corresponding distances separating the donor nucleotide in one monomer from acceptors on Cys-10 in the first and second nearest neighbours in F-actin are 39-40 A and 41-43 A. 相似文献
25.
Cytochrome oxidase vesicles catalyzed the peroxidatic oxidation of ferrocytochrome c. The maximal peroxidase activity in the absence of an uncoupling agent was 9.8 mol ferrocytochrome c oxidized/(s X mol heme a), indicating a 5-fold activation compared with the soluble enzyme system. The peroxidase activity was further enhanced 1.2 to 2.1 times upon addition of an uncoupler, carbonyl cyanide p-trifluoromethoxyphenyl hydrazone. The stoichiometry of the reduction of hydrogen peroxide by ferrocytochrome c was established to be 1 : 2, indicating water formation. Potassium cyanide (0.14 mM) completely inhibited the peroxidase activity. The inhibition by 1 mM CO was 40-77% depending on the energized state of cytochrome oxidase vesicles, but in contrast, 85% inhibition was observed with the soluble enzyme. In the energized state the enzyme showed a slightly lower affinity for CO than in the deenergized state. Coupled with the peroxidase activity, a membrane potential of 72 mV was registered transiently; this may be physiologically significant in relation to the energy transduction mechanism. 相似文献
26.
M Inaba H Morii Y Nishizawa T Miki M Yukioka S Morisawa A Inoue 《Journal of biochemistry》1986,100(3):591-595
Calcitonin (CT) stimulated phosphorylation of two liver cytosolic proteins whose molecular weights are 67,000 and 93,000. Stimulation of 67,000-Mr protein phosphorylation began shortly after subcutaneous injection of CT, reaching a maximum at 5 min and decreasing to below the control level at 30 min. The reaction was independent of cyclic AMP or Ca2+, and was not influenced by a calmodulin antagonist, W7. Stimulation of 93,000-Mr protein phosphorylation became evident by 30 min. This reaction was also stimulated by administration of vasopressin or epinephrine, which is known to cause increased phosphorylation of glycogen phosphorylase having the same molecular weight. The phosphorylation of 93,000-Mr protein, stimulated by CT, was dependent on Ca2+ but not on cyclic AMP, and appeared to be inhibited by W7. In addition, CT did not influence the phosphorylation of 61,000-Mr protein, a major protein phosphorylated in a cyclic AMP-dependent manner. These results suggest that CT may exert its effect on liver cells through protein phosphorylation, most probably in a cyclic AMP-independent manner. 相似文献
27.
Coupled with the peroxidatic oxidation of ferrocytochrome c under anaerobic conditions, proteoliposomes reconstituted with a purified preparation of bovine heart cytochrome oxidase ejected protons into the external medium with an apparent H+/e- ratio of 0.9. At the same time, protons in the intravesicular space were consumed. Dicyclohexylcarbodiimide significantly inhibited the proton translocation. Cyanide (0.14 mM) completely inhibited both the peroxidase and proton translocating activities. On the contrary, in the presence of 1 mM CO the proton ejection was abolished almost completely, but 50% of the peroxidase activity persisted. This result suggests the operation of multiple mechanisms in the peroxidase reaction and that the CO-sensitive one is coupled to the proton translocation. 相似文献
28.
The reaction of horseradish peroxidase with hydroperoxides derived from Triton X-100 总被引:1,自引:0,他引:1
All of the commercially available Triton X-100 examined gave Compound I upon reaction with horseradish peroxidase, followed by its gradual transition into Compound II. Titration of horseradish peroxidase with Triton X-100 to form Compound I indicated that 1% (v/v) aqueous solutions of the detergent contained 0.4 to 3.2 microM equivalent peroxide but iodometric titration revealed 1.1 to 5.0 microM peroxide, suggesting the occurrence of different types of peroxides, reactive and unreactive with the peroxidase. The rate constant for Compound I formation was 1.5 X 10(7) M-1 S-1 at pH 7.4 at 25 degrees C, and for conversion into Compound II apparent first-order rate constants were 5.2 X 10(-3) to 1.7 X 10(-2) S-1. These results indicate that the Triton peroxides are as highly reactive as hydrogen peroxide. The amount of Triton peroxides increased as aqueous solutions of the detergent were allowed to stand, but the peroxides were destroyed by treatment with sodium borohydride. Although freshly prepared aqueous solutions of sodium cholate, sodium dodecyl sulfate, Tween 20 (polyoxyethylene sorbitan monolaurate), and Emasol 1130 (an equivalent of Tween 20) did not contain any detectable amount of peroxide, aged solutions of sodium dodecyl sulfate and Emasol 1130 contained peroxides. These observations suggest the need for appropriate precautions when biologically active substances vulnerable to attack by peroxides are incubated with Triton X-100 either for their solubilization from biomembranes or for other processing. 相似文献
29.
K Yamamura T Miki N Suzuki T Ebihara K Kawai Y Kumahara T Honjo 《Journal of biochemistry》1985,97(1):333-339
A fragment of the cloned gene for the mouse C epsilon chain, coding for the first, second, third, and fourth domains, has been coupled to the SV40 promotor region (pSV2-mC epsilon). About 50 copies of pSV2-mC epsilon or its PvuII-EcoRI fragments were introduced into Cos-7 cells. Expression of PvuII-EcoRI fragments of pSV2-mC epsilon was observed in about 50% of the Cos-7 cells by indirect fluorescence staining. However, no expression of circular pSV2-mC epsilon was observed. About 200 copies of linearized pSV2-mC epsilon with EcoRI were introduced into fertilized mouse eggs. Two of 78 mice born from these eggs had integrated mouse C epsilon genes. Mouse C epsilon gene was shown to be integrated in a tandem array and as intact structures without undergoing gross deletions or rearrangements, judged from the Southern blotting patterns from several restriction enzymes. The first transgenic mouse was mated to a normal male to examine whether mouse C epsilon gene were stably transmitted to progeny. Among 5 mice to which the C epsilon gene had been transmitted, one deleted 5 copies of this gene and another deleted one junction fragment, thus demonstrating relatively unstable transmission. No C epsilon mRNA was detected in the liver, kidney, brain, lung, skeletal muscle, heart, testis, or spleen of a transgenic mouse. 相似文献
30.
Toru Miki 《Ichthyological Research》1985,32(2):137-142
Specimens of a new genus and species of the stichaeid fish,Leptostichaeus pumilus, were collected from the Okhotsk Sea off Hokkaido in Japan. The present new genus and species clearly differs from all the other genera and species of the stichaeid fishes in the following characters: 3 or 4 pectoral fin rays; 10 or fewer caudal principal rays; 79–82 dorsal spines; no pelvic fin; last interneural spine supporting a single dorsal spine; infraorbital, occipital and lateral line canals absent; moderate size of dorsal spine shorter than eye diameter; membranes of dorsal and anal fins widely connected with caudal fin; a large black spot divided by a yellow band present just above gill cover. 相似文献