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101.
Summary The ultrastructural organization of ommatidial components of the retina of the moth, Galleria mellonella are described from electron microscopic observations. Each ommatidium is composed of 12 common retinula cells and one basal eccentric cell. The retinula cells are connected together by a desmosomal strip along their length. The rhabdom occupies the basal thirty percent of the ommatidium and can be divided into nine segments of parallel microvilli. Several cells may contribute to an individual rhabdomere. The rhabdomeres are arranged in a cross with single cell rhabdomeres lying between the arms of the cross. Thin sections of ommatidium absorb polarized light differentially. The total amount of plane polarized light absorbed varies with angle of rotation for an entire ommatidium but there are also differences between the amount of absorption of adjacent rhabdomeric segments. Galleria appears to be the only lepidopteran in which the possibility of the polarized light reception has been reported. 相似文献
102.
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104.
The 100,000 xg supernatant of rabbit kidney contains a prostaglandin-E2-9-ketoreductase which has an obligatory requirement for NADPH. This enzyme is localised in the renal cortex and is able to quantitatively convert PGE2 to PGF2α. A broad pH profile was evident with an optimum at pH 7·5. Kinetic studies indicated a Km of 3·2 × 10−4M PGE2. The isoelectric point was at pH 5·65 and the molecular weight, as estimated by gel filtration, was 21,800. These values differ from those obtained with enzyme from monkey brain tissue and suggest a tissue specificity of PGE2-9-ketoreductase. By combining isoelectric focussing techniques with sephadex filtration considerable purification of the renal enzyme was achieved. 相似文献
105.
Gold salts and phenylbutazone selectively inhibit the synthesis of PGF2α and PGE2 respectively. Lowered production of one prostaglandin species is accompanied by an increased production of the other. Selective inhibition by these drugs was observed in the presence of adrenaline, reduced glutathione and copper sulphate under conditions when most anti-inflammatory compounds inhibited PGE2 and PGF2α syntheses equally. It is postulated that selective inhibitors may have a different mode of action
and beneficial effects may be related to the endogenous ratio of PGE to PGF required for normal function. 相似文献
106.
Zhang J Tanha J Hirama T Khieu NH To R Tong-Sevinc H Stone E Brisson JR MacKenzie CR 《Journal of molecular biology》2004,335(1):49-56
We describe a novel type of molecule in which single-domain antibodies (sdAbs) isolated from a nai;ve llama single domain antibody library are linked to an oligomerization domain to generate high-avidity, antigen-binding reagents. An sdAb is fused to the B-subunit of Escherichia coli verotoxin, or shiga-like toxin, which self-assembles to form a homopentamer and results in simultaneous sdAb pentamerization and introduction of avidity. Molecular modeling indicated that this fusion protein (PDB: 1OJF), termed pentabody, has structural flexibility for binding to surface-presented antigen. In the instance of an sdAb specific for a peptide antigen, pentamerization resulted in a dramatic increase in functional affinity for immobilized antigen. The pentabody was expressed in high yield in E.coli in a non-aggregated state, and exhibited excellent thermostability and protease resistance. This technology provides a relatively rapid means of generating novel antigen-binding molecules that bind strongly to immobilized antigen. It is expected that pentavalent sdAbs will have general applicability in proteomics, immunochemical staining, cancer diagnosis and other applications in which antigens are presented multivalently. 相似文献
107.
Tu WC Mühlhäusler BS James MJ Stone DA Gibson RA 《Biochemical and biophysical research communications》2012,423(1):176-182
Desaturase and elongase are two key enzyme categories in the long-chain polyunsaturated fatty acid (LCPUFA) pathway that convert dietary α-linolenic acid (18:3n-3) to docosahexaenoic acid (22:6n-3). The Δ6 desaturase is considered as rate limiting in the conversion. In a previous study in barramundi we demonstrated that the desaturase had a low Δ6 activity but noted that the enzyme also possessed Δ8 ability that utilised 20-carbon fatty acids. This observation suggests that an alternative pathway may exist in the barramundi via elongases to form 20-carbon metabolites from 18:3n-3 to 20:3n-3 and then Δ6/8 desaturase to 20:4n-3. Cloning of the barramundi elongation of very long-chain fatty acid gene (ELOVL) and heterologous expression of the corresponding elongase were performed to examine activity with regard to time course, substrate concentration and substrate preference. Results revealed that the barramundi elongase showed a broad range of substrate specificity including 18-carbon PUFA (including 18:3n-3 and 18:2n-6), 20- and 22-carbon LCPUFA, with greater activity towards omega-3 (n-3) than n-6 fatty acids. The findings from this study provide molecular evidence for an alternative n-3 fatty acid elongation pathway utilising 18:3n-3 in barramundi. 相似文献
108.
Shepard SR Stone C Cook S Bouvier A Boyd G Weatherly G Lydiard D Schrimsher J 《Journal of biotechnology》2002,99(2):149-160
A cell permeabilization method for the release of intracellular proteins from microbial cells was developed. The method was applied to the recovery of recombinant botulinum neurotoxin fragments, expressed intracellularly in the yeast Pichia pastoris, by suspending the cells in an aqueous solution containing N,N-dimethyltetradecylamine. For the botulinum neurotoxin serotype B C-terminal heavy chain fragment, 1.8 mg g(-1) biomass were recovered. For the botulinum neurotoxin serotype A C-terminal heavy chain fragment, 3.7 mg g(-1) biomass were recovered. The concentration of recombinant protein in the cell extracts remained stable for up to 48 and 24 h for the serotype B and serotype A fragments, respectively. The permeabilization method was compared with high-pressure homogenization; the permeabilization method proved to be both more selective and more efficient. 相似文献
109.
Poole JA Kielian T Wyatt TA Gleason AM Stone J Palm K West WW Romberger DJ 《American journal of physiology. Lung cellular and molecular physiology》2011,301(3):L296-L306
Nucleotide-binding oligomerization domain 2 (NOD2) is involved in innate immune responses to peptidoglycan degradation products. Peptidoglycans are important mediators of organic dust-induced airway diseases in exposed agriculture workers; however, the role of NOD2 in response to complex organic dust is unknown. Monocytes/macrophages were exposed to swine facility organic dust extract (ODE), whereupon NOD2 expression was evaluated by real-time PCR and Western blot. ODE induced significant NOD2 mRNA and protein expression at 24 and 48 h, respectively, which was mediated via a NF-κB signaling pathway as opposed to a TNF-α autocrine/paracrine mechanism. Specifically, NF-κB translocation increased rapidly following ODE stimulation as demonstrated by EMSA, and inhibition of the NF-κB pathway significantly reduced ODE-induced NOD2 expression. However, there was no significant reduction in ODE-induced NOD2 gene expression when TNF-α was inhibited or absent. Next, it was determined whether NOD2 regulated ODE-induced inflammatory cytokine production. Knockdown of NOD2 expression by small interfering RNA resulted in increased CXCL8 and IL-6, but not TNF-α production in response to ODE. Similarly, primary lung macrophages from NOD2 knockout mice demonstrated increased IL-6, CXCL1, and CXCL1, but not TNF-α, expression. Lastly, a higher degree of airway inflammation occurred in the absence of NOD2 following acute (single) and repetitive (3 wk) ODE exposure in an established in vivo murine model. In summary, ODE-induced NOD2 expression is directly dependent on NF-κB signaling, and NOD2 is a negative regulator of complex, organic dust-induced inflammatory cytokine/chemokine production in mononuclear phagocytes. 相似文献
110.
Use of bovine EST data and human genomic sequences to map 100 gene-specific bovine markers 总被引:4,自引:0,他引:4
Roger T. Stone W. Michael Grosse Eduardo Casas Timothy P.L. Smith John W. Keele Gary L. Bennett 《Mammalian genome》2002,13(4):211-215
A system to use bovine EST data in conjunction with human genomic sequence to improve the bovine linkage map over the entire
genome or on specific chromosomes was evaluated. Bovine EST sequence was used to provide primer sequences corresponding to
bovine genes, while human genomic sequence directed primer design to flank introns and produce amplicons of appropriate size
for efficient direct sequencing. The sequence tagged sites (STS) produced in this way from the four sires of the MARC reference
families were examined for single nucleotide polymorphisms (SNPs) that could be used to map the corresponding genes. With
this approach, along with a primer/extension mass spectrometry SNP genotyping assay, 100 ESTs were placed on the bovine genetic
linkage map. The first 70 were chosen at random from bovine EST–human genomic comparisons. An additional 30 ESTs were successfully
mapped to bovine Chromosome 19 (BTA19), and comparison of the resulting BTA19 map to the position of the corresponding human
orthologs on the HSA17 draft sequences revealed differences in the spacing and order of genes. Over 80% of successful amplicons
contained SNPs, indicating that this is an efficient approach to generating EST-associated genetic markers. We have demonstrated
the feasibility of constructing a linkage map based on SNPs associated with ESTs and the plausibility of utilizing EST, comparative
mapping information, and human sequence data to target regions of the bovine genome for SNP marker development. 相似文献