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1.
The mannoprotein which is a major component of the cell wall of Saccharomyces cerevisiae is an effective bioemulsifier. Mannoprotein emulsifier was extracted in a high yield from whole cells of fresh bakers' yeast by two methods, by autoclaving in neutral citrate buffer and by digestion with Zymolase (Miles Laboratories; Toronto, Ontario, Canada), a beta-1,3-glucanase. Heat-extracted emulsifier was purified by ultrafiltration and contained approximately 44% carbohydrate (mannose) and 17% protein. Treatment of the emulsifier with protease eliminated emulsification. Kerosene-in-water emulsions were stabilized over a broad range of conditions, from pH 2 to 11, with up to 5% sodium chloride or up to 50% ethanol in the aqueous phase. In the presence of a low concentration of various solutes, emulsions were stable to three cycles of freezing and thawing. An emulsifying agent was extracted from each species or strain of yeast tested, including 13 species of genera other than Saccharomyces. Spent yeast from the manufacture of beer and wine was demonstrated to be a possible source for the large-scale production of this bioemulsifier. 相似文献
2.
Protamine sulfate inhibits mitogenic activities of the extracellular matrix and fibroblast growth factor, but potentiates that of epidermal growth factor 总被引:11,自引:0,他引:11
Protamine sulfate, an inhibitor of angiogenesis in vivo, markedly inhibits the ability of angiogenic factors such as acidic or basic fibroblast growth factor (aFGF, bFGF) to stimulate the proliferation in vitro of either BHK-21 cells or vascular endothelial cells. The inhibition is reversible, and cells remain viable even after prolonged exposure to protamine sulfate. Protamine sulfate inhibits the mitogenic effects of both growth factors by preventing them from binding to their common cell surface receptors. It also inhibits the mitogenic activity of the extracellular matrix produced by bovine corneal endothelial cells. This substrate has been shown in previous studies to replace the requirement for FGF of many cell types. In contrast, protamine sulfate potentiates the mitogenic activity of epidermal growth factor (EGF). This indicates that protamine sulfate also acts at cellular sites which are not associated with FGF receptors. 相似文献
3.
Immortalization of human fibroblasts transformed by origin-defective simian virus 40. 总被引:16,自引:6,他引:10 下载免费PDF全文
Simian virus 40 (SV40)-mediated transformation of human diploid fibroblasts has provided an effective experimental system for studies of both "senescence" in cell culture and carcinogenesis. Previous interpretations may have been complicated, however, by the semipermissive virus-cell interaction. In earlier studies, we previously demonstrated that the human diploid fibroblast line HS74 can be efficiently transformed by DNA from replication-defective mutants of SV40 containing a deletion in the viral origin for DNA synthesis (SVori-). In the current study, we found that such SVori- transformants show a significantly increased life span in culture, as compared with either HS74 or an independent transformant containing an intact viral genome, but they nonetheless undergo senescence. We have clonally isolated six immortalized derivatives of one such transformant (SV/HF-5). Growth studies indicate that the immortalized cell lines do not invariably grow better than SV/HF-5 or HS74. Genetic studies involving karyotypic analysis and Southern analysis of integrated viral sequences demonstrated both random and nonrandom alterations. All immortalized derivatives conserved one of the two copies of SV40 sequences which expressed a truncated T antigen. These cloned SV40-transformed cell lines, pre- and postimmortalization, should be useful in defining molecular changes associated with immortalization. 相似文献
4.
During investigation of biodegradation in soil, we have found that classical or standard techniques for introduction of compounds and the growth of fungus into soil are ill-defined and inadequate. In response to this deficiency, a method for controlled introduction of extractable compounds and for the growth of fungus in soils has been developed. This method was successfully used to study the degradation of fluorene in soil by the fungus Phanerochaete chrysosporium. 相似文献
5.
Expression of human basic fibroblast growth factor cDNA in baby hamster kidney-derived cells results in autonomous cell growth 总被引:19,自引:5,他引:14 下载免费PDF全文
Growth factor over-production by responsive cells might contribute to their autonomous proliferation as well as their acquisition of a transformed phenotype in culture. Basic fibroblast growth factor (bFGF) has been shown to induce transient changes in cell behavior that resemble those encountered in transformed cells. In addition, several types of human tumor cells have been shown to produce bFGF. To determine directly the role that bFGF might play in the induction of the transformed phenotype, we have introduced a human bFGF cDNA expression vector into baby hamster kidney-derived (BHK-21) fibroblasts. One of the BHK transfectants, termed clone 19, expresses the bFGF mRNA and produces biologically active bFGF that accumulates to a high concentration inside the cells. These properties correlate with the ability of the cells to grow in serum-free medium without the addition of exogenous bFGF. Clone 19 cells also proliferated in soft agar, indicating that constitutive expression of the bFGF gene results in a loss of anchorage-dependent growth. 相似文献
6.
E E Grebner D A Mansfield S S Raghavan E H Kolodny A d'Azzo E F Neufeld L G Jackson 《American journal of human genetics》1986,38(4):505-514
Two abnormalities of beta-hexosaminidase A (HEX A) activity are described. One, found in two unrelated Jewish children, was characterized by the complete absence of HEX A activity in serum, but low levels of activity in leukocytes and fibroblasts using artificial substrate. The other, found in a non-Jewish man, was characterized by uniformly low levels of HEX A activity in leukocytes, fibroblasts, and serum against artificial substrate. In all cases, the pH optimum of HEX A was normal, there was no increased lability at 37 degrees C, and no inhibitor was detected to account for the deficiency of activity. Cultured fibroblasts of these individuals were capable of synthesizing and processing alpha- and beta-subunits of HEX A and capable of cleaving GM2 ganglioside. The patients, ranging in age from 6 to 30 years, are clinically normal. They are probably genetic compounds carrying the classical Tay-Sachs gene and a differently mutated allele that imparts the anomalous phenotypic features observed. 相似文献
7.
Basic and acidic fibroblast growth factors interact with the same cell surface receptors 总被引:35,自引:0,他引:35
Despite quantitative differences, the activity of basic and acidic fibroblast growth factors (FGF) on a wide variety of normal diploid cells derived from neuroectoderm and mesoderm is intrinsically similar. This suggests that they bind to the same cell surface receptors. This was investigated using a baby hamster kidney cell line (BHK-21) as a model. BHK-21 cell membrane components that interact with basic and acidic FGF have been identified by covalent cross-linking to their respective 125I-labeled ligands. Under appropriate conditions, basic and acidic 125I-FGF were cross-linked, using disuccinimidyl suberate, to two receptor species with apparent molecular masses of 145,000 and 125,000 daltons, respectively. The labeling of those receptors is inhibited when either native basic or acidic FGF are present in excess during incubation of cells with either acidic or basic 125I-FGF. Competition of basic 125I-FGF with increasing concentrations of native acidic FGF results in a preferential decrease in the labeling of the 125,000-dalton species, whereas competition of acidic 125I-FGF with increasing concentrations of native basic FGF leads to a preferential decrease in the labeling of the 145,000-dalton species. The data suggest that qualitatively both mitogens interact with the same 145,000- and 125,000-dalton receptor species. The different affinities displayed by acidic and basic FGF toward their common receptor molecules could explain why acidic FGF, depending on the cell type considered, is 20-100-fold less potent than basic FGF. 相似文献
8.
Association of alpha- and beta-subunits during the biosynthesis of beta-hexosaminidase in cultured human fibroblasts 总被引:18,自引:0,他引:18
Subunit association of beta-hexosaminidase was studied in intact fibroblasts using antisera that discriminate between free and associated alpha-chains. These were anti-beta-hexosaminidase A (anti-alpha beta), which precipitated all alpha-chains, free or associated; anti-beta-hexosaminidase B (anti-beta beta), which precipitated those alpha-chains that were associated with beta; and anti-alpha-chains, which recognized only monomeric alpha-chains. After biosynthetic labeling, beta-hexosaminidase or its free alpha-subunit were immuno-precipitated from extracts of cells and medium with the aid of protein A-bearing Staphylococcus aureus, subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and visualized by fluorography. Pulse-chase labeling showed that the alpha-chains existed predominantly in the monomeric precursor form during the first 5 h, and then began to accumulate in the mature (lysosomal) associated alpha beta form. Precursor alpha beta complexes were secreted, along with some precursor alpha monomers; the latter were catalytically inert. Both alpha- and beta-chains were phosphorylated (a Golgi modification) prior to association. Thus alpha-beta association probably occurred in the Golgi area before transfer to lysosomes and before secretion. Cycloheximide inhibited the association and subsequent maturation of preformed alpha-chains, perhaps by causing a depletion of a pool of beta-chain precursor upstream from the site of subunit association. In fibroblasts from a patient with Sandhoff disease, that produced no beta-chains, the alpha-chains self-associated but their maturation was markedly decreased. We suggest that association with beta-chains is necessary not only for acquisition of catalytic activity but also for transport of alpha-chains to lysosomes. 相似文献
9.
Gideon Bach Elizabeth F. Neufeld 《Biochemical and biophysical research communications》1983,112(1):198-205
The biosynthesis of arylsulfatase A was studied in cultured fibroblasts by pulse-chase labeling with [2-3H]mannose; the enzyme was isolated by immunoprecipitation and denaturing polyacrylamide gel electrophoresis. In normal fibroblasts, and in fibroblasts from a patient with multiple sulfatase deficiency, the enzyme was synthesized as a glycoprotein of apparent molecular weight of 59,000; half of it was processed over a period of 4 days to Mr= 57,000. The precursor chain of Mr= 59,000 was secreted in the presence of 10 mM NH4Cl. An immunoprecipitable glycoprotein of normal size was synthesized by fibroblasts from two unrelated patients with metachromatic leukodystrophy, but this material disappeared within twenty hours. In fibroblasts from an individual with pseudodeficiency of arylsulfatase A, the immunoprecipitable precursor glycoprotein was smaller (Mr= 56,000). The synthesis of cross-reactive proteins with altered properties supports the concept of allelic mutations as the genetic basis of metachromatic leukodystrophy and of arylsulfatase A pseudodeficiency. 相似文献
10.
Biochemical heterogeneity of the Sanfilippo syndrome: preliminary characterization of two deficient factors 总被引:8,自引:0,他引:8
H Kresse U Wiesmann M Cantz C W Hall E F Neufeld 《Biochemical and biophysical research communications》1971,42(5):892-898
Fibroblasts cultured from the skin of Sanfilippo patients show excessive accumulation and prolonged turnover time of sulfated mucopolysaccharide. This abnormality can be corrected by a macromolecular factor contained in the secretions of fibroblasts of differing genotype, as well as in normal human urine. By cross-correction tests, the Sanfilippo fibroblasts can be subdivided into two groups, each deficient in a different factor. Analytical polyacrylamide gel electrophoresis shows the two factors, which are probably proteins, to have a similar molecular weight (ca. 200,000) but to differ in charge at pH 8.5. 相似文献