全文获取类型
收费全文 | 1563篇 |
免费 | 121篇 |
专业分类
1684篇 |
出版年
2023年 | 8篇 |
2022年 | 10篇 |
2021年 | 13篇 |
2020年 | 9篇 |
2019年 | 16篇 |
2018年 | 12篇 |
2017年 | 20篇 |
2016年 | 24篇 |
2015年 | 35篇 |
2014年 | 57篇 |
2013年 | 61篇 |
2012年 | 95篇 |
2011年 | 78篇 |
2010年 | 59篇 |
2009年 | 69篇 |
2008年 | 70篇 |
2007年 | 96篇 |
2006年 | 74篇 |
2005年 | 80篇 |
2004年 | 67篇 |
2003年 | 67篇 |
2002年 | 88篇 |
2001年 | 34篇 |
2000年 | 49篇 |
1999年 | 42篇 |
1998年 | 13篇 |
1997年 | 21篇 |
1996年 | 14篇 |
1995年 | 16篇 |
1994年 | 21篇 |
1993年 | 14篇 |
1992年 | 25篇 |
1991年 | 20篇 |
1990年 | 36篇 |
1989年 | 31篇 |
1988年 | 36篇 |
1987年 | 28篇 |
1986年 | 15篇 |
1985年 | 18篇 |
1984年 | 15篇 |
1983年 | 32篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1980年 | 10篇 |
1979年 | 17篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1976年 | 3篇 |
1975年 | 7篇 |
1973年 | 5篇 |
排序方式: 共有1684条查询结果,搜索用时 15 毫秒
1.
2.
Multiple-sulfatase deficiency (MSD) is now considered to be heterogeneous and could be classified into three or four clinical phenotypes according to the onset of the disease: neonatal, late infantile, juvenile and possibly adult type. Neonatal-type MSD shows severe clinical involvement and practically no arylsulfatase A, B and C activities in cultured skin fibroblasts. Furthermore, arylsulfatase A activity in neonatal-type MSD was not enhanced by the addition of thiosulfate. Therefore, it is distinct from late infantile-type MSD. The degradation of 14C-sulfatide can occur in MSD-cultured skin fibroblasts and was much higher than in late infantile-type MLD. The addition of thiol protease such as leupeptin to cultured MSD skin fibroblasts enhanced arylsulfatase A activity as well as the degradation of 14C-sulfatide. This suggests that the decreased activities of arylsulfatase A is due to an acceleration of the enzyme degradation. Enzyme replacement by the addition of arylsulfatases of different sources (human liver, brain, fungus) was carried out in cultured MSD skin fibroblasts. Human enzymes of arylsulfatase A and B were mostly taken up by MSD cells rather than those of fungus origin. By the exposure to leukocytes to cultured skin fibroblasts, MSD cells corrected arylsulfatase A and B activities. 相似文献
3.
4.
Assignment of the human myeloperoxidase gene (MPO) to bands q21.3----q23 of chromosome 17 总被引:1,自引:0,他引:1
J Inazawa K Inoue H Nishigaki S Tsuda M Taniwaki S Misawa T Abe 《Cytogenetics and cell genetics》1989,50(2-3):135-136
Using a human myeloperoxidase cDNA, we have mapped the human myeloperoxidase gene to chromosome 17 at q21.3----q23 by in situ hybridization to metaphase chromosomes from human lymphocyte preparations. 相似文献
5.
Rat pineal S-antigen: sequence analysis reveals presence of alpha-transducin homologous sequence 总被引:2,自引:0,他引:2
T Abe K Yamaki M Tsuda V K Singh S Suzuki R McKinnon D C Klein L A Donoso T Shinohara 《FEBS letters》1989,247(2):307-311
S-antigen (S-Ag) is a soluble, highly antigenic protein, the administration of which induces autoimmune uveitis. This protein is found in the retina and pineal. Retinal S-Ag from three species has been sequenced. In this study rat pineal S-Ag was sequenced. Clones were isolated from a rat pineal lambda gt11 cDNA library by probing with a 300 bp fragment of mouse retinal S-Ag cDNA containing the 5'-coding region. The largest clone isolated (RPS-118; 1364 bp) contained the entire coding sequence. Comparison of the rat pineal and mouse retinal S-Ag nucleotide sequences indicated a high homology (95%). The deduced amino acid sequence was found to contain 403 residues (congruent to 44 992 Da). Comparison of the rat pineal and mouse retinal S-Ag amino acid sequences also revealed high homology (97%). The similarity of both the nucleotide and amino acid sequences of rat pineal and mouse retinal S-Ag indicates that expression of the S-Ag gene in both tissues is similar. Further analysis of the rat pineal S-Ag sequence indicated that it contained essentially the same major uveitopathogenic region of S-Ag present in bovine retina; minor uveitopathogenic sites were somewhat different. As is true of retinal S-Ag, rat pineal S-Ag contains the same consensus phosphoryl-binding site present in many GTP/GDP-binding proteins and a homologous sequence found in the C-terminus of alpha-transducin. These sequences may play a role in the action of pineal S-Ag in transmembrane signal transduction. 相似文献
6.
M Miwa M Tsuda Y Kurashima H Hara Y Tanaka K Shinohara 《Biochemical and biophysical research communications》1989,159(2):373-378
Thioproline (Thiazolidine-4-carboxylic acid) and proline were nitrosated by stimulated mouse macrophages in vitro. A macrophage cell line (J774.1, 1.0 x 10(6)/well, 1 ml) was incubated with Escherichia coli lipopolysaccharide, interferon-gamma and thioproline (5 mM) or proline (5 mM). After 72 hr incubation at 37 degrees C, 4 microM N-nitrosothioproline was produced. The amount of N-nitrosoproline was much lower than that of N-nitrosothioproline. Thioproline and proline inhibited the formation of carcinogenic N-nitrosomorpholine. N-nitrosothioproline and N-nitrosoproline are found as major N-nitroso compounds in human urine. Macrophage mediated N-nitrosation may contribute to the formation of these N-nitrosamino acids in the human body. 相似文献
7.
M Kawata Y Kawahara S Araki M Sunako T Tsuda H Fukuzaki A Mizoguchi Y Takai 《Biochemical and biophysical research communications》1989,163(3):1418-1427
At least two GTP-binding proteins (G proteins) with Mr values of about 20,000 were extracted from bovine aortic smooth muscle membranes by sodium cholate. The most abundant G protein (22K G) was purified to near homogeneity by successive column chromatographies of Ultrogel AcA-44, phenyl-Sepharose CL-4B, hydroxyapatite and Mono Q HR5/5. 22K G showed kinetic and physical properties very similar to those of smg p21, a G protein recently isolated from bovine brain and human platelet membranes, having the same effector domain as ras p21s. Moreover, 22K G was recognized specifically by the anti-smg p21 antibody. These results indicate that the major G protein in bovine aortic smooth muscle membranes is smg p21. 相似文献
8.
Regeneration of bovine and octopus opsins in situ with natural and artificial retinals 总被引:4,自引:0,他引:4
Y Koutalos T G Ebrey M Tsuda K Odashima T Lien M H Park N Shimizu F Derguini K Nakanishi H R Gilson 《Biochemistry》1989,28(6):2732-2739
We consider the problem of color regulation in visual pigments for both bovine rhodopsin (lambda max = 500 nm) and octopus rhodopsin (lambda max = 475 nm). Both pigments have 11-cis-retinal (lambda max = 379 nm, in ethanol) as their chromophore. These rhodopsins were bleached in their native membranes, and the opsins were regenerated with natural and artificial chromophores. Both bovine and octopus opsins were regenerated with the 9-cis- and 11-cis-retinal isomers, but the octopus opsin was additionally regenerated with the 13-cis and all-trans isomers. Titration of the octopus opsin with 11-cis-retinal gave an extinction coefficient for octopus rhodopsin of 27,000 +/- 3000 M-1 cm-1 at 475 nm. The absorption maxima of bovine artificial pigments formed by regenerating opsin with the 11-cis dihydro series of chromophores support a color regulation model for bovine rhodopsin in which the chromophore-binding site of the protein has two negative charges: one directly hydrogen bonded to the Schiff base nitrogen and another near carbon-13. Formation of octopus artificial pigments with both all-trans and 11-cis dihydro chromophores leads to a similar model for octopus rhodopsin and metarhodopsin: there are two negative charges in the chromophore-binding site, one directly hydrogen bonded to the Schiff base nitrogen and a second near carbon-13. The interaction of this second charge with the chromophore in octopus rhodopsin is weaker than in bovine, while in metarhodopsin it is as strong as in bovine. 相似文献
9.
DNA ploidy pattern and amplification of ERBB and ERBB2 genes in human gastric carcinomas 总被引:1,自引:0,他引:1
N Oda T Tsujino T Tsuda K Yoshida H Nakayama W Yasui E Tahara 《Virchows Archiv. B, Cell pathology including molecular pathology》1990,58(4):273-277
The DNA ploidy pattern and amplification of ERBB and ERBB2 genes were examined in paraffin-embedded tissue from gastric carcinomas using flow cytometry and a slot-blot hybridization technique. The incidence of aneuploidy in well differentiated adenocarcinomas (56%) was significantly higher (p less than 0.05) than that in poorly differentiated adenocarcinomas (21%). The DNA ploidy pattern was not remarkably different between the primary tumors and metastatic deposits in lymph nodes. Of the nine specimens having an aneuploid stem cell line in the primary tumor and/or in metastases, three showed ERBB2 gene amplification and one showed ERBB gene amplification. The incidence of epidermal growth factor (EGF) immunoreactivity in tumor cells showed no difference between diploid and aneuploid tumors. These findings indicate that aneuploidy is frequently associated with amplification of ERBB and ERBB2 genes. 相似文献
10.
The dose dependent effect of ipriflavone (7-isopropoxy-isoflavone) on the femoral bone in streptozotocin-induced diabetic rats was studied by microdensitometric analysis. Diabetic rats showed severe hyperglycemia, glucosuria, hypoinsulinemia, associated with increased urinary calcium and hydroxyproline. Microdensitometric analysis revealed decreases in femoral length, bone width, and bone density. The dietary administration of ipriflavone (about 270 mg/kg/day) to the diabetic rats for 6 weeks prevented reduction of the cortical thickness index in the diaphysis and depletion of bone density in the distal metaphysis, and also reduced the inner diameter of the diaphysis; diabetic state was not improved. A simple correlation and linear regression analysis revealed that ipriflavone also significantly reduced the inner diameter in the diaphysis at a dose of 90 mg/kg/day, but not at one of 25 mg/kg/day. These results suggest that ipriflavone suppresses the depletion of the femoral bone through inhibition of bone resorption in a dose dependent fashion; its minimum effective dose is 90 mg/kg/day in experimental diabetes. 相似文献