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951.
A simple procedure is described for preparing GM3 ganglioside, from a few milligrams to grams, from GM1-lactone (Sonnino et al., (1985) Glycoconjugate J 2: 343-54) [1]. The synthesis was carried out under the following optimal conditions: 30 mM GM1-lactone in 0.25 M H2SO4 in DMSO, 30 min, 70 degrees C, nitrogen atmosphere, strong stirring. The yield of GM3 was 55%. The procedure applied to milligram amounts of GD1b-dilactone gave GD3 ganglioside. 相似文献
952.
Destro-Bisol G Maviglia R Caglià A Boschi I Spedini G Pascali V Clark A Tishkoff S 《Human genetics》1999,104(2):149-157
We have analyzed 10 unlinked microsatellites and a linked Alu deletion polymorphism at the CD4 locus in an African American population sample from Chicago (USA). Heterozygosity estimates
at the microsatellite loci range from 0.727±0.025 (D3S1358) to 0.873±0.017 (D18S51), with an average of 0.794±0.016. These
values are comparable to or higher than those reported for Europeans, with only one exception (D3S1358). The CD4/Alu haplotypic diversity (0.887±0.012) is comparable to diversity levels observed in sub-Saharan African populations and is higher
than the diversity levels reported in European populations. No consistent pattern of within, between, or multi-locus deviations
from Hardy-Weinberg expectations is observed, suggesting a low sub-heterogeneity within the sampled population. We have applied
a maximum likelihood method and estimated the proportion of European admixture to the African American gene pool to be 0.26±0.02.
The narrow confidence interval indicates that allele frequency data from multiple microsatellite loci, whether analyzed independently
or as haplotypes, are particularly useful for estimating genetic admixture.
Received: 9 September 1998 / Accepted: 3 November 1998 相似文献
953.
Chiusaroli R Sanjay A Henriksen K Engsig MT Horne WC Gu H Baron R 《Developmental biology》2003,261(2):537-547
During development of the skeleton, osteoclast (OC) recruitment and migration are required for the vascular invasion of the cartilaginous anlage and the ossification of long bones. c-Cbl lies downstream of the vitronectin receptor and forms a complex with c-Src and Pyk2 in a signaling pathway that is required for normal osteoclast motility. To determine whether the decreased motility we observed in vitro in c-Cbl(-/-) OCs translated into decreased cell migration in vivo, we analyzed the long bones of c-Cbl(-/-) mice during development. Initiation of vascularization and replacement of cartilage by bone were delayed in c-Cbl(-/-) mice, due to decreased osteoclast invasion of the hypertrophic cartilage through the bone collar. Furthermore, c-Cbl(-/-) mice show a delay in the formation of secondary centers of ossification, a thicker hypertrophic zone of the growth plate, and a prolonged presence of cartilaginous remnants in the spongiosa, confirming a decrease in resorption of the calcified cartilage. Thus, the decrease in motility of c-Cbl(-/-) osteoclasts observed in vitro results in a decreased ability of osteoclasts to invade and resorb bone and mineralized cartilage in vivo. These results confirm that c-Cbl plays an important role in osteoclast motility and resorbing activity. 相似文献
954.
Degl'Innocenti D Ramazzotti M Marzocchini R Chiti F Raugei G Ramponi G 《FEBS letters》2003,535(1-3):171-174
Analysis of the Drosophila melanogaster EST database led to the characterization of a novel acylphosphatase (AcPDro2). This is coded by the CG18505 (Acyp2) gene and is clearly distinct from a previously described AcPDro coded by the CG16870 (Acyp) gene from D. melanogaster. The two proteins show a 60% homology with both vertebrate isoenzymes. All the residues involved in the catalytic mechanism are conserved. AcPDro2 is a stable enzyme with a correct globular folded structure. Its activity on benzoylphosphate shows higher K(cat) but lower K(m) with respect to AcPDro. It is possible that AcPDro and AcPDro2 genes are not the direct ancestor of MT and CT vertebrate isoenzymes. 相似文献
955.
Alberghina L Rossi RL Wanke V Querin L Vanoni M 《The Italian journal of biochemistry》2003,52(1):55-57
The regulation of cell cycle progression via the attainment of a critical cell size is a conserved feature from simpler unicellular organisms to mammalian cells that is obtaining much attention recently. Genome wide analysis of Saccharomyces cerevisiae deletion strains, genetic epistasis, DNA microarray analysis have recently revealed an increasingly complex network of cell size modulation mechanisms. A systems biology-based approach, that is needed to structure the underlying complexity of cell cycle regulatory mechanisms, is described. 相似文献
956.
Degumming of silk fabric with several proteases 总被引:4,自引:0,他引:4
A crêpe silk fabric was treated with different alkaline (3374-L, GC 897-H), neutral (3273-C), and acid (EC 3.4 23.18) proteases with the aim to study their effectiveness as degumming agents. Proteases were used under optimum conditions of pH and temperature, while enzyme dosage (0.05-2 U/g fabric) and treatment time (5-240 min) were changed in order to study the kinetics of sericin removal. Degumming loss with soap and alkali was 27 wt.%. The maximum amount of sericin removed in 1 h was 17.6, 24, and 19 wt.% for 3374-L (2 U/g fabric), GC 897-H (1U/g fabric), and 3273-C (0.1 U/g fabric), respectively. Under the experimental conditions adopted, EC 3.4 23.18 was almost ineffective as a degumming agent. Degumming loss increased as a function of the treatment time, reaching a value of 25 wt.% with 1 U/g fabric of 3374-L. The morphological analysis showed that sericin was completely removed from the warp yarns of the crêpe fabric, while the highly twisted weft yarns still exhibited the presence of sericin deposits within the most internal parts of the close fibre texture. The chromatographic pattern of soluble sericin peptides changed as a function of the kind of enzyme used, enzyme dosage, and treatment time. A mixture of peptides from 5 to 20 kDa in weight, with a weight-average molecular weight of about 12 kDa was obtained. 相似文献
957.
Polyamine oxidase,a hydrogen peroxide-producing enzyme,is up-regulated by light and down-regulated by auxin in the outer tissues of the maize mesocotyl 总被引:11,自引:0,他引:11
Cona A Cenci F Cervelli M Federico R Mariottini P Moreno S Angelini R 《Plant physiology》2003,131(2):803-813
Exogenously supplied auxin (1-naphthaleneacetic acid) inhibited light-induced activity increase of polyamine oxidase (PAO), a hydrogen peroxide-producing enzyme, in the outer tissues of maize (Zea mays) mesocotyl. The same phenomenon operates at PAO protein and mRNA accumulation levels. The wall-bound to extractable PAO activity ratio was unaffected by auxin treatment, either in the dark or after light exposure. Ethylene treatment did not affect PAO activity, thus excluding an effect of auxin via increased ethylene biosynthesis. The auxin polar transport inhibitors N(1)-naphthylphthalamic acid or 2,3,5-triiodobenzoic acid caused a further increase of PAO expression in outer tissues after light treatment. The small increase of PAO expression, normally occurring in the mesocotyl epidermis during plant development in the dark, was also inhibited by auxin, although to a lesser extent with respect to light-exposed tissue, and was stimulated by N(1)-naphthylphthalamic acid or 2,3,5-triiodobenzoic acid, thus suggesting a complex regulation of PAO expression. Immunogold ultrastructural analysis in epidermal cells revealed the association of PAO with the secretory pathway and the cell walls. The presence of the enzyme in the cell walls of this tissue greatly increased in response to light treatment. Consistent with auxin effects on light-induced PAO expression, the hormone treatment inhibited the increase in immunogold staining both intraprotoplasmically and in the cell wall. These results suggest that both light and auxin finely tune PAO expression during the light-induced differentiation of the cell wall in the maize mesocotyl epidermal tissues. 相似文献
958.
There is no generally accepted method for assessing abstracts that are submitted for a medical scientific meeting. This article describes the development and prospective evaluation of such a method applied to the 220 abstracts submitted for the 2000 Annual Meeting of the European Association of Plastic Surgeons. Structured abstracts were evaluated in three categories: aesthetic surgery, basic research, and clinical study. Each anonymous abstract was assessed separately by 10 reputable European plastic surgeons. These reviewers used a structured rating questionnaire which resulted in a score given by each reviewer to each abstract between -6 and +6. The scores of all 10 reviewers were added for each abstract, and the papers were accepted in each of the three categories on the basis of this abridged score. To evaluate the reliability of this structured method of selection, the interrater agreement among the reviewers was tested by means of kappa analysis and the Cronbach alpha coefficient. The kappa values for agreement among reviewers regarding acceptability of abstracts were low, but the alpha coefficient indicated an acceptable degree of reliability of the average reviewers' ratings for all categories. Using a structured questionnaire can be helpful in the objective assessment of abstracts for a scientific meeting and may facilitate comparison of abstracts. Meritocratic dichotomy of abstracts by the reviewers is advocated to further improve reliability of the rating. Even though reliability generally increases with the number of reviewers, the annual increase of submitted abstracts may necessitate a decrease in the number of reviewers for each abstract. 相似文献
959.
A variation in 3' UTR of hPTP1B increases specific gene expression and associates with insulin resistance 总被引:19,自引:0,他引:19 下载免费PDF全文
Di Paola R Frittitta L Miscio G Bozzali M Baratta R Centra M Spampinato D Santagati MG Ercolino T Cisternino C Soccio T Mastroianno S Tassi V Almgren P Pizzuti A Vigneri R Trischitta V 《American journal of human genetics》2002,70(3):806-812
Protein tyrosine phosphatase 1B (PTP1B) inhibits insulin signaling and, when overexpressed, plays a role in insulin resistance (Ahmad et al. 1997). We identified, in the 3' untranslated region of the PTP1B gene, a 1484insG variation that, in two different populations, is associated with several features of insulin resistance: among male individuals, higher values of the insulin resistance HOMA(IR) index (P=.006), serum triglycerides (P=.0002), and total/HDL cholesterol ratio (P=.025) and, among female individuals, higher blood pressure (P=.01). Similar data were also obtained in a family-based association study by use of sib pairs discordant for genotype (Gu et al. 2000). Subjects carrying the 1484insG variant showed also PTP1B mRNA overexpression in skeletal muscle (6,166 plus minus 1,879 copies/40 ng RNA vs. 2,983 plus minus 1,620; P<.01). Finally, PTP1B mRNA stability was significantly higher (P<.01) in human embryo kidney 293 cells transfected with 1484insG PTP1B, as compared with those transfected with wild-type PTP1B. Our data indicate that the 1484insG allele causes PTP1B overexpression and plays a role in insulin resistance. Therefore, individuals carrying the 1484insG variant might particularly benefit from PTP1B inhibitors, a promising new tool for treatment of insulin resistance (Kennedy and Ramachandran 2000). 相似文献
960.
Searching for DNA-protein interactions by lambda phage display 总被引:5,自引:0,他引:5
Cicchini C Ansuini H Amicone L Alonzi T Nicosia A Cortese R Tripodi M Luzzago A 《Journal of molecular biology》2002,322(4):697-706