全文获取类型
收费全文 | 799篇 |
免费 | 68篇 |
出版年
2021年 | 9篇 |
2018年 | 10篇 |
2017年 | 13篇 |
2016年 | 13篇 |
2015年 | 23篇 |
2014年 | 35篇 |
2013年 | 32篇 |
2012年 | 42篇 |
2011年 | 29篇 |
2010年 | 19篇 |
2009年 | 25篇 |
2008年 | 21篇 |
2007年 | 26篇 |
2006年 | 30篇 |
2005年 | 23篇 |
2004年 | 21篇 |
2003年 | 16篇 |
2002年 | 25篇 |
2001年 | 25篇 |
2000年 | 22篇 |
1999年 | 27篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1996年 | 10篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 16篇 |
1991年 | 14篇 |
1990年 | 18篇 |
1989年 | 13篇 |
1988年 | 17篇 |
1987年 | 29篇 |
1986年 | 14篇 |
1985年 | 15篇 |
1984年 | 10篇 |
1983年 | 17篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 14篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1976年 | 9篇 |
1975年 | 11篇 |
1974年 | 8篇 |
1973年 | 17篇 |
1972年 | 7篇 |
1969年 | 6篇 |
1967年 | 6篇 |
排序方式: 共有867条查询结果,搜索用时 24 毫秒
21.
22.
23.
Sexual and somatic determinants of the human Y chromosome: studies in a 46,XYp- phenotypic female. 总被引:5,自引:0,他引:5 下载免费PDF全文
R G Rosenfeld L Luzzatti R L Hintz O J Miller G C Koo S S Wachtel 《American journal of human genetics》1979,31(4):458-468
A case of a 46,XYp- phenotypic female provided an opportunity to evaluate both sexual and somatic determinants for the Y chromosome. The patient had multiple stigmata of Turner syndrome, but normal stature. Laparotomy revealed a normal uterus and tubes, with 1.5 cm undifferentiated gonads. Serological tests for H-Y antigen (ostensibly the product of Y-chromosomal testis-determining genes) indicated absence of the H-Y+ phenotype normally associated with the intact Y chromosome. We conclude that genes exist on the short arm of the human Y chromosome which both suppress some of the somatic stigmata of Turner syndrome and determine normal expression of H-Y antigen and testicular differentiation of the primitive gonad. Our data are consistent with the view that H-Y genes comprise a family of testis-determinants, and that loss of a critical moiety is inconsistent with normal development of the male gonad. 相似文献
24.
Summary A new way of detecting neuraminidase activity on the surface of neuraminidase-treated cells is described. It consists of an enzymatic assay with radiolabelled cells as substrate. It shows that the enzyme borne by one cell is able to cleave sialic acid to another cell. 相似文献
25.
Frank C. Bennett Barry I. Rosenfeld Cheng-Hsiung Huang Lynn C. Yeoman 《Biochemical and biophysical research communications》1982,104(2):649-656
Nonhistone protein BAfree was purified from the 0.075 M NaCl/0.025 M 8 extract of whole rat liver nuclei while protein BAbound was isolated from the 0.05 M Na2HPO4/8 M urea/1% β-mercaptoethanol/pH 7.6 extract of dehistonized rat liver chromatin. Chromatin associated protein BAbound was able to bind 60% of the [3H] DNA in a nitrocellulose filter binding assay while nucleoplasmic protein BAfree showed essentially no DNA binding activity. Circular dichroism analysis of the two forms of protein BA revealed substantial differences in their conformations. Protein BAfree was found to have an α-helix content of 41% while protein BAbound displayed a spectrum more typical of unordered or β-turn structures. 相似文献
26.
C P Chang J P Kao C S Lazar B J Walsh A Wells H S Wiley G N Gill M G Rosenfeld 《The Journal of biological chemistry》1991,266(34):23467-23470
Signals that can mediate ligand-induced receptor internalization and calcium regulation are present in a 48-amino acid "calcium-internalization" domain in the C' terminus of the epidermal growth factor (EGF) receptor. The basis of calcium and internalization regulation signalled by this 48-amino acid sequence was analyzed using deletion and substitution mutant receptors. Cells expressing truncated receptors containing either the NH2- or COOH-terminal portion of the 48-residue domain displayed high affinity EGF-dependent endocytosis and receptor down-regulation. These endocytosis-competent EGF receptor mutants that lacked any autophosphorylation site were unable to increase the concentration of intracellular calcium. To investigate the role of self-phosphorylation in EGF-induced calcium mobilization, phenylalanine was substituted for the single autophosphorylated tyrosine residue in this region of an internalization-competent truncated receptor. The receptor-mediated calcium response was abolished, while ligand-dependent receptor internalization was unimpaired. These results demonstrate that EGF-dependent receptor endocytosis and calcium mobilization are separate events. Tyrosine self-phosphorylation is required for increased [Ca2+]i, while structural features distinct from autophosphorylation are required for receptor internalization. 相似文献
27.
H C Haspel D C Mynarcik P A Ortiz R A Honkanen M G Rosenfeld 《Molecular endocrinology (Baltimore, Md.)》1991,5(1):61-72
Antibody to the carboxyl-terminal of hexose transporter protein GLUT-1 was used to localize this carrier in normal rat kidney (NRK) cells during D-glucose (Glc) deprivation. Glc-deprivation of NRK cells induces increased hexose transport, inhibits the glycosylation of GLUT-1, and increases the content of both native, 55,000 apparent mol wt (Mr) and aglyco, 38,000 Mr GLUT-1 polypeptides. The distribution of GLUT-1 protein in subcellular fractions isolated from Glc-fed NRK cells shows that the 55,000 Mr polypeptide is most abundant in intracellular membrane fractions. Glc-fed cells that have been tunicamycin treated contain principally the 38,000 Mr GLUT-1 polypeptide, which is found predominantly in intracellular membrane fractions. In Glc-deprived cells the 55,000 Mr GLUT-1 polypeptide localizes predominantly in the Golgi and plasma membrane fractions, whereas the more abundant 38,000 Mr GLUT-1 polypeptide is distributed throughout all membrane fractions. In Glc-deprived but fructose-fed cells only the 55,000 Mr GLUT-1 polypeptide is detected, and it is found predominantly in the plasma membrane and Golgi fractions. The localization of GLUT-1 protein was directly and specifically visualized in NRK cells by immunofluorescence microscopy. Glc-fed cells show little labeling of cell borders and a small punctate juxtanuclear pattern suggestive of localization to the Golgi and, perhaps, endoplasmic reticulum. Glc-fed cells that have been tunicamycin treated show large punctate intracellular accumulations suggestive of localization to distended Golgi and perhaps endoplasmic reticulum. Glc-deprived cells exhibited intense labeling of cell borders as well as intracellular accumulations. Glc-deprived but fructose-fed cells show fewer intracellular accumulations, and the labeling is, in general, limited to the cell borders. Our results suggest that Glc deprivation induces the selective accumulation of GLUT-1 in the plasma membrane of NRK cells. 相似文献
28.
29.
Biosynthesis of lysosomal hydrolases: their synthesis in bound polysomes and the role of co- and post-translational processing in determining their subcellular distribution 总被引:37,自引:20,他引:17 下载免费PDF全文
By in vitro translation of mRNA’s isolated from free and membrane-bound polysomes, direct evidence was obtained for the synthesis of two lysosomal hydrolases, β-glucuronidase of the rat preputial gland and cathespin D of mouse spleen, on polysomes bound to rough endoplasmic reticulum (ER) membranes. When the mRNA’s for these two proteins were translated in the presence of microsomal membranes, the in vitro synthesized polypeptides were cotranslationally glycosylated and transferred into the microsomal lumen. Polypeptides synthesized in the absence of microsomal membranes were approximately 2,000 daltons larger than the respective unglycosylated microsomal polypeptides found after short times of labeling in cultured rat liver cells treated with tunicamycin. This strongly suggests that nascent chains of the lysosomal enzymes bear transient amino terminal signals which determine synthesis on bound polysomes and are removed during the cotranslational insertion of the polypeptides into the ER membranes. In the line of cultured rat liver cells used for this work, newly synthesized lysosomal hydrolases showed a dual destination; approximately 60 percent of the microsomal polypeptides detected after short times of labeling were subsequently processed proteolytically to lower molecular weight forms characteristic of the mature enzymes. The remainder was secreted from the cells without further proteolytic processing. As previously observed by other investigations in cultured fibroblasts (A. Gonzalez-Noriega, J.H. Grubbs, V. Talkad, and W.S. Sly, 1980, J Cell Biol. 85: 839-852; A. Hasilik and E.F. Neufeld, 1980, J. Biol. Chem., 255:4937-4945.) the lysosomotropic amine chloroquine prevented the proteolytic maturation of newly synthesized hydrolases and enhanced their section. In addition, unglycosylated hydrolases synthesized in cells treated with tunicamycin were exclusively exported from the cells without undergoing proteolytic processing. These results support the notions that modified sugar residues serve as sorting out signals which address the hydrolases to their lysosomal destination and that final proteolytic cleavage of hydrolase precursors take place within lysosome itself. Structural differences in the carbohydrate chains of intracellular and secreted precursors of cathespin D were detected from their differential sensitivity to digestion with endoglycosidases H and D. These observations suggest that the hydrolases exported into the medium follow the normal secretory route and that some of their oligosaccharides are subject to modifications known to affect many secretory glycoproteins during their passage through the Golgi apparatus. 相似文献
30.
Details of a sensitive and specific radioimmunoassay for androsterone (1) and androsterone sulfate in plasma have been presented. Benzene extracts of plasma were chromatographed on a lumina to isolate the androsterone fraction either (a) directly after extraction (A) or (b) after solvolysis (AS). Following treatment with rabbit anti-A-17-BSA, antibody bound steroid was precipitated by ammonium sulfate. Androsterone concentrations in normal male plasma averaged 57 ± 24 (S.D.) ng/dl, range 35–135 ng/dl and for normal women, 44 ± 21 (S.D.) ng/dl, range 18–98 ng/dl. Androsterone sulfate concentrations were: males 55 ± 28 μg/dl (range 10–114 μg/dl); premenopausal females 52 ± 31 μg/dl (range 16–318 μg/dl). 相似文献