全文获取类型
收费全文 | 588篇 |
免费 | 50篇 |
国内免费 | 196篇 |
出版年
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 24篇 |
2020年 | 12篇 |
2019年 | 20篇 |
2018年 | 10篇 |
2017年 | 13篇 |
2016年 | 17篇 |
2015年 | 20篇 |
2014年 | 23篇 |
2013年 | 24篇 |
2012年 | 52篇 |
2011年 | 44篇 |
2010年 | 42篇 |
2009年 | 39篇 |
2008年 | 37篇 |
2007年 | 35篇 |
2006年 | 27篇 |
2005年 | 26篇 |
2004年 | 20篇 |
2003年 | 16篇 |
2002年 | 35篇 |
2001年 | 22篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 19篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 8篇 |
1994年 | 11篇 |
1993年 | 10篇 |
1992年 | 22篇 |
1991年 | 14篇 |
1990年 | 8篇 |
1989年 | 14篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1975年 | 4篇 |
1973年 | 5篇 |
1972年 | 7篇 |
1967年 | 6篇 |
1956年 | 3篇 |
排序方式: 共有834条查询结果,搜索用时 15 毫秒
1.
Hiroyoshi Fujita Yutaka Orii Seiyo Sano 《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,678(1):39-50
δ-Aminolevulinic acid dehydratase (porphobilinogen synthase; 5-aminolevulinate hydro-lyase, EC 4.2.1.24) was purified from rat and rabbit erythrocytes to a homogeneous state. Specific activities were 26.0 and 26.6 units/mg protein for the rat and rabbit enzymes, respectively, and their estimated molecular weight was 280 000, each consisting of 8 subunits of Mr 35 000. In order to quantitate rat δ-aminolevulinic acid dehydratase at several stages of lead-poisoning, a radioimmunoassay technique using goat antiserum against the rat enzyme was developed for the first time. This technique was specific, reproducible and high sensitive allowing determination of 1 ng enzyme. When drinking water containing 25 mM lead acetate was given daily to rats ad lib. the δ-aminolevulinic acid dehydratase activity in the blood, assayed without any pretreatment, decreased to 8% of the control level on the next day. On the contrary, the restored enzyme activity, assayed in the presence of Zn2+ and dithiothreitol, was greater than normal by the fourth day of lead administration in bone-marrow cells and by the ninth day in the peripheral blood. The increased activity level stayed the same from the ninth day onward. The enzyme content as determined directly by the radioimmunoassay technique at this stage was about 2-fold above that the control. There was no significant difference in the number of reticulocytes and the distribution profile of different types of reticulocytes between the lead-exposed and non-exposed rats. Therefore, the increase in the amount of δ-aminolevulinic acid dehydratase in erythrocytes of lead-poisoned rats was suggested to be due to an increased rate of synthesis in the bone-marrow cells. 相似文献
2.
Nishizono Hiromi; Watanabe Takemasa; Orii Tokiko; Suzuki Shizuo 《Plant & cell physiology》1989,30(4):565-569
A metal-tolerant fern, Athyrium yokoscense, is capable of growingin highly copper-contaminated soil, but cupric chloride inhibitedthe activities of some enzymes extracted from the fern. Thefunction in the detoxification of copper of two copper-bindingsubstances was investigated by examination of their effectson various enzymes assayed in vitro, i.e. acid phosphatase (orthophosphoric-monoesterphosphohydrolase [acid optimum], EC 3.1.3.2
[EC]
), glucose-6-phosphatedehydrogenase (D-glucose-6-phosphate: NADP+ 1-oxidoreductase,EC 1.1.1.49
[EC]
) and isocitrate dehydrogenase (threo-Ds-isocitrate:NADP+ oxidoreductase [decarboxylating], EC 1.1.1.42
[EC]
). The twocopper-binding substances, whose apparent molecular weightsare 9.5 kDa and 2 kDa, were previously obtained from the solublecytoplasmic fraction of the fern root. The 9.5-kDa substance,which is a cysteine-rich peptide induced as a result of exposureof the fern to copper, was found to suppress almost entirelythe inhibitory effects of the metal on the enzymes. The suppressoractivity of the peptide was nearly as effective as that of ethylenediaminetetraaceticacid. The 2-kDa substance, which is also found in fern thathas not been exposed to copper, had a more modest suppressoractivity. These results indicate that the 9.5-kDa substancemay contribute to the copper-tolerance of the fern growing incopper-contaminated soil. (Received August 26, 1988; Accepted March 17, 1989) 相似文献
3.
Summary A 444leucine to proline mutation detected by a NciI polymorphism in the human glucocerebrosidase gene was studied to investigate the correlation of the three clinical phenotypes of Gaucher disease with this mutation in 11 Japanese patients with Gaucher disease (type I, 8 patients; type II, 1 patient; type III, 2 patients) and to determine the feasibility of the use of genomic probe DNA for carrier detection and prenatal diagnosis in 8 Japanese families with Gaucher disease and agreeable to family study (type I, 6 families; type III, 2 families). The homoallelic 444leucine to proline mutation was found only in patients with type I disease. Of the 8 type I patients, 5 had the homoallelic mutation and 2 had one mutant allele. One patient with type II disease did not have this mutant allele. Of the 2 type III patients, one had a single mutant allele whereas the other exhibited no mutation of this kind. These results suggest that the 444leucine to proline mutation is very common in the type I (non-neuronopathic form) disease and is not tightly associated only with neuronopathic types of Gaucher disease in Japanese patients. These findings seem to conflict with others showing that this mutation is partially responsible for the occurrence of neuronopathic Gaucher disease. Thus, the NciI polymorphism will not be useful for the diagnosis of subtypes of Gaucher disease. Carrier detection was feasible in three families with type I disease of the 8 families analyzed by the NciI polymorphism. 相似文献
4.
作者在广东省梅县市发现四个吸虫新种:1.鼠丽色吸虫,新种Reesella ratta sp. nov., 2.后囊蛙蠕吸虫,新种Batrachotrema optstosacca sp. nov., 3.梅县后平睾吸虫,新种Opisthioparorchis meixianensis sp. nov., 4.大卵后平睾吸虫,新种Opisthioparorchis megaloonos sp. nov.,它们分别归隶于蹲茎科Cathaemasiidae及蛙蠕科Bstrachotrematidae。模式标本保存于中山医科大学寄生虫学研究所。 相似文献
5.
6.
Complementation study of peroxisome-deficient disorders by immunofluorescence staining and characterization of fused cells 总被引:5,自引:0,他引:5
Shigehiro Yajima Yasuyuki Suzuki Nobuyuki Shimozawa Seiji Yamaguchi Tadao Orii Yukio Fujiki Takashi Osumi Takashi Hashimoto Hugo W. Moser 《Human genetics》1992,88(5):491-499
Summary Genetic heterogeneity in peroxisome-deficient disorders, including Zellweger's cerebrohepatorenal syndrome, neonatal adrenoleukodystrophy and infantile Refsum disease, was investigated. Fibroblasts from 17 patients were fused using polyethylene glycol, cultivated on cover slips, and the formation of peroxisomes in the fused cells was visualized by immunofluorescence staining, using anti-human catalase IgG. Two distinct staining patterns were observed: (1) peroxisomes appeared in the majority of multinucleated cells, and (2) practically no peroxisomes were identified. Single step 12-(1-pyrene) dodecanoic acid/ultraviolet (P12/UV)-selection confirmed that the former groups were resistant to this selection, most of the surviving cells contained abundant peroxisomes, and the latter cells died. In the complementary matching, [1-14C]lignoceric acid oxidation and the biosynthesis of peroxisomal proteins were also normalized. Five complementation groups were identified. Group A: Zellweger syndrome and infantile Refsum disease; Groups B, C and D: Zellweger syndrome; Group E: Zellweger syndrome, neonatal adrenoleukodystrophy and infantile Refsum disease. We compared these groupings with those of Roscher and identified eight complementation groups. There was no obvious relation between complementation groups and clinical phenotypes. These results indicate that the transport, intracellular processing and function of peroxisomal proteins were normalized in the complementary matching and that at least eight different genes are involved in the formation of normal peroxisomes and in the transport of peroxisomal enzymes. 相似文献
7.
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
8.
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
9.
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
10.