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141.
Lucotte GL;French MS Consortium 《Genetic counseling (Geneva, Switzerland)》2002,13(2):133-138
To identify the chromosomal localizations of the multiple sclerosis (MS) genes, we conducted a genomewide linkage analysis using eighteen affected families. A MS gene is linked to markers located in the 19q13.3 region (multipoint lod-score = 2.1). Apolipoprotein E (ApoE) gene, located in this region, is an excellent candidate gene for MS because the ApoEe4 allele is acting as a severity allele in the disease. 相似文献
142.
In Situ Spatial Patterns of Soil Bacterial Populations,Mapped at Multiple Scales,in an Arable Soil 总被引:2,自引:0,他引:2
Very little is known about the spatial organization of soil microbes across scales that are relevant both to microbial function
and to field-based processes. The spatial distributions of microbes and microbially mediated activity have a high intrinsic
variability. This can present problems when trying to quantify the effects of disturbance, management practices, or climate
change on soil microbial systems and attendant function. A spatial sampling regime was implemented in an arable field. Cores
of undisturbed soil were sampled from a 3 × 3 × 0.9 m volume of soil (topsoil and subsoil) and a biological thin section,
in which the in situ distribution of bacteria could be quantified, prepared from each core. Geostatistical analysis was used
to quantify the nature of spatial structure from micrometers to meters and spatial point pattern analysis to test for deviations
from complete spatial randomness of mapped bacteria. Spatial structure in the topsoil was only found at the microscale (micrometers),
whereas evidence for nested scales of spatial structure was found in the subsoil (at the microscale, and at the centimeter
to meter scale). Geostatistical ranges of spatial structure at the micro scale were greater in the topsoil and tended to decrease
with depth in the subsoil. Evidence for spatial aggregation in bacteria was stronger in the topsoil and also decreased with
depth in the subsoil, though extremely high degrees of aggregation were found at very short distances in the deep subsoil.
The data suggest that factors that regulate the distribution of bacteria in the subsoil operate at two scales, in contrast
to one scale in the topsoil, and that bacterial patches are larger and more prevalent in the topsoil. 相似文献
143.
The sensitivity of myeloma cells to high dose chemotherapy has led to the use of allogeneic hematopoietic stem cell transplantation (HSCT) as a therapeutic modality in this disease. In addition to providing more effective chemotherapy, the transplantation of allogeneic stem cells also initiates the development of an allogeneic immune response directed against residual myeloma cells. Direct evidence for a graft vs. myeloma (GVM) effect is provided by the ability of donor lymphocyte infusion (DLI) to induce significant responses in 30-50% of patients with myeloma who have relapsed after allogeneic HSCT. Nevertheless, allogeneic stem cell transplantation is also associated with a high incidence of transplant related toxicities, including regimen-related toxicities, graft vs. host disease (GVHD) and opportunistic infections. DLI has been shown to enhance immune reconstitution after allogeneic HSCT in addition to inducing a GVM response. Current efforts are directed at reducing the toxicities associated with allogeneic HSCT, identification of the target antigens of GVM and the development of new strategies to selectively enhance the immune response to myeloma cells. 相似文献
144.
145.
Substitution bias, rapid saturation, and the use of mtDNA for nematode systematics 总被引:13,自引:0,他引:13
Only relatively recently have researchers turned to molecular methods for
nematode phylogeny reconstruction. Thus, we lack the extensive literature
on evolutionary patterns and phylogenetic usefulness of different DNA
regions for nematodes that exists for other taxa. Here, we examine the
usefulness of mtDNA for nematode phylogeny reconstruction and provide data
that can be used for a priori character weighting or for parameter
specification in models of sequence evolution. We estimated the
substitution pattern for the mitochondrial ND4 gene from intraspecific
comparisons in four species of parasitic nematodes from the family
Trichostrongylidae (38-50 sequences per species). The resulting pattern
suggests a strong mutational bias toward A and T, and a lower
transition/transversion ratio than is typically observed in other taxa. We
also present information on the relative rates of substitution at first,
second, and third codon positions and on relative rates of saturation of
different types of substitutions in comparisons ranging from intraspecific
to interordinal. Silent sites saturate extremely quickly, presumably owing
to the substitution bias and, perhaps, to an accelerated mutation rate.
Results emphasize the importance of using only the most closely related
sequences in order to infer patterns of substitution accurately for
nematodes or for other taxa having strongly composition-biased DNA. ND4
also shows high amino acid polymorphism at both the intra- and
interspecific levels, and in higher level comparisons, there is evidence of
saturation at variable amino acid sites. In general, we recommend using
mtDNA coding genes only for phylogenetics of relatively closely related
nematode species and, even then, using only nonsynonymous substitutions and
the more conserved mitochondrial genes (e.g., cytochrome oxidases). On the
other hand, the high substitution rate in genes such as ND4 should make
them excellent for population genetics studies, identifying cryptic
species, and resolving relationships among closely related congeners when
other markers show insufficient variation.
相似文献
146.
Differentiation-associated modulation of heparan sulfate structure and function in CaCo-2 colon carcinoma cells 总被引:3,自引:2,他引:1
Salmivirta M; Safaiyan F; Prydz K; Andresen MS; Aryan M; Kolset SO 《Glycobiology》1998,8(10):1029-1036
Heparan sulfate species expressed by different cell and tissue types differ
in their structural and functional properties. Limited information is
available on differences in regulation of heparan sulfate biosynthesis
within a single tissue or cell population under different conditions. We
have approached this question by studying the effect of cell
differentiation on the biosynthesis and function of heparan sulfate in
human colon carcinoma cells (CaCo-2). These cells undergo spontaneous
differentiation in culture when grown on semipermeable supports; the
differentiated cells show phenotypic similarity to small intestine
enterocytes. Metabolically labeled heparan sulfate was isolated from the
apical and basolateral media from cultures of differentiated and
undifferentiated cells. Compositional analysis of disaccharides, derived
from the contiguous N-sulfated regions of heparan sulfate, indicated a
greater proportion of 2-O- sulfated iduronic acid units and a smaller
amount of 6-O-sulfated glucosamine units in differentiated than in
undifferentiated cells. By contrast, the overall degree of sulfation, the
chain length and the size distribution of the N-acetylated regions were
similar regardless the differentiation status of the cells. The structural
changes were found to affect the binding of heparan sulfate to the long
isoform of platelet-derived growth factor A chain but not to fibroblast
growth factor 2. These findings show that heparan sulfate structures change
during cell differentiation and that heparan sulfate-growth factor
interactions may be affected by such changes.
相似文献
147.
K W Heimberg C Matthews E Ritz J Augustin W Hasselbach 《European journal of biochemistry》1976,61(1):207-213
The Ca-transport system of sarcoplasmic vesicles of rabbits is altered by experimental uremia. 1. The influx rate constant of the experimental membranes decrease with a resulting decrease of the calcium influx rate. 2. The experimental membranes transport a smaller amount of Ca2+ per mol of ATP split than the controls, i.e. their transport ratio is discussed. 3. The calcium permeability of the experimental membranes increases with a resulting decreased concentrating ability. 4. The phosphatide content but not the cholesterol content of the experimental membranes decreases with a consequent increase of the cholesterol/phosphatide ratio. 5. The fatty acid pattern of total phosphatides of the experimental membranes changes. A relative decrease of palmitic acid and oleic acid occurs and a relative increase of stearic, arachidonic and higher unsaturated fatty acids. 6. The altered lipid composition of the membranes does not change the temperature dependence of the kinetics. 相似文献
148.
The short-tailed shearwater (muttonbird) Puffinus tenuirostris (Temminck) and the fairy prion Pachyptila turtur (Kuhl) are procellariiform birds which feed extensively on the euphausiid Nyctiphanes australis Sars in south eastern Tasmania. Data from a hydrodynamic study of the heads of the two birds were used to develop a simple qualitative model of food capture. This model predicts that as the bird moves through the water the open gape, aided by the bill architecture, produces and maintains a low pressure volume into which the prey is sucked. Once inside the bill euphausiids are prevented from escaping by filtering systems which differ in the two birds. In the muttonbird, the filtering mesh consists of retroverted papillae of the upper palate which overlap with opposing papillae on the tongue. In the fairy prion a combination of papillae in the oral cavity and a series of closely-set lamellae on the margins of the upper palate serve to retain the krill. 相似文献
149.
Henrik Friis Bernardette Cichon Christian Fabiansen Ann-Sophie Iuel-Brockdorff Charles W. Yamogo Christian Ritz Ruth Frikke-Schmidt Andr Briend Kim F. Michaelsen Vibeke B. Christensen Suzanne Filteau Mette F. Olsen 《PLoS medicine》2022,19(3)
BackgroundAmong children with moderate acute malnutrition (MAM) the level of serum cobalamin (SC) and effect of food supplements are unknown. We aimed to assess prevalence and correlates of low SC in children with MAM, associations with hemoglobin and development, and effects of food supplements on SC.Methods and findingsA randomized 2 × 2 × 3 factorial trial was conducted in Burkina Faso. Children aged 6 to 23 months with MAM received 500 kcal/d as lipid-based nutrient supplement (LNS) or corn–soy blend (CSB), containing dehulled soy (DS) or soy isolate (SI) and 0%, 20%, or 50% of total protein from milk for 3 months. Randomization resulted in baseline equivalence between intervention groups. Data on hemoglobin and development were available at baseline. SC was available at baseline and after 3 and 6 months. SC was available from 1,192 (74.1%) of 1,609 children at baseline. The mean (±SD) age was 12.6 (±5.0) months, and 54% were females. Low mid-upper arm circumference (MUAC; <125 mm) was found in 80.4% (958) of the children and low weight-for-length z-score (WLZ; <−2) in 70.6% (841). Stunting was seen in 38.2% (456). Only 5.9% were not breastfed. Median (IQR) SC was 188 (137; 259) pmol/L. Two-thirds had SC ≤222 pmol/L, which was associated with lower hemoglobin. After age and sex adjustments, very low SC (<112 pmol/L) was associated with 0.21 (95% CI: 0.01; 0.41, p = 0.04) and 0.24 (95% CI: 0.06; 0.42, p = 0.01) z-score lower fine and gross motor development, respectively.SC data were available from 1,330 (85.9%) of 1,548 children followed up after 3 months and 398 (26.5%) of the 1,503 children after 6 months. Based on tobit regression, accounting for left censored data, and adjustments for correlates of missing data, the mean (95% CI) increments in SC from baseline to the 3- and 6-month follow-up were 72 (65; 79, p < 0.001) and 26 (16; 37, p < 0.001) pmol/L, respectively. The changes were similar among the 310 children with SC data at all 3 time points. Yet, the increase was 39 (20; 57, p < 0.001) pmol/L larger in children given LNS compared to CSB if based on SI (interaction, p < 0.001). No effect of milk was found. Four children died, and no child developed an allergic reaction to supplements. The main limitation of this study was that only SC was available as a marker of status and was missing from a quarter of the children.ConclusionsLow SC is prevalent among children with MAM and may contribute to impaired erythropoiesis and child development. The SC increase during supplementation was inadequate. The bioavailability and adequacy of cobalamin in food supplements should be reconsidered.Trial registrationISRCTN Registry ISRCTN42569496.Henrik Friis and colleagues, investigate the prevalence and correlates of low serum cobalamin, associations with hemoglobin and child development, and associations of serum cobalamin levels with food supplementation in children moderate acute malnutrition in Burkina Faso. 相似文献
150.
Ritz D Patel H Doan B Zheng M Aslund F Storz G Beckwith J 《The Journal of biological chemistry》2000,275(4):2505-2512