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71.
P Santoro G Parisi V Guerriero 《Bollettino della Società italiana di biologia sperimentale》1990,66(12):1237-1243
The orange coloration of the marine sponge A. verrucosa is provided by some carotenoids widespread in the ectosome and mesohyl of this sponge. These carotenoids are bound to a glyco(lipo)protein forming a non covalent complex. Six carotenoids are bound to the glyco(lipo)protein, but only alpha-carotene was identified by HPLC. The aminoacid composition is quite different from those previously reported in Porifera. The content of Ser and Gly and the total polar residues are high. The presence of Met and Pro was not evidenced. Some unusual aminoacids were detected, of which only Taurine was probably identified. 相似文献
72.
A covariotide model explains apparent phylogenetic structure of oxygenic photosynthetic lineages 总被引:17,自引:13,他引:4
Lockhart PJ; Steel MA; Barbrook AC; Huson DH; Charleston MA; Howe CJ 《Molecular biology and evolution》1998,15(9):1183-1188
The aims of the work were (1) to develop statistical tests to identify
whether substitution takes place under a covariotide model in sequences
used for phylogenetic inference and (2) to determine the influence of
covariotide substitution on phylogenetic trees inferred for photosynthetic
and other organisms. (Covariotide and covarion models are ones in which
sites that are variable in some parts of the underlying tree are invariable
in others and vice versa.) Two tests were developed. The first was a
contingency test, and the second was an inequality test comparing the
expected number of variable sites in two groups with the observed number.
Application of these tests to 16S rDNA and tufA sequences from a range of
nonphotosynthetic prokaryotes and oxygenic photosynthetic prokaryotes and
eukaryotes suggests the occurrence of a covariotide mechanism. The degree
of support for partitioning of taxa in reconstructed trees involving these
organisms was determined in the presence or absence of sites showing
particular substitution patterns. This analysis showed that the support for
splits between (1) photosynthetic eukaryotes and prokaryotes and (2)
photosynthetic and nonphotosynthetic organisms could be accounted for by
patterns arising from covariotide substitution. We show that the additional
problem of compositional bias in sequence data needs to be considered in
the context of patterns of covariotide/covarion substitution. We argue that
while covariotide or covarion substitution may give rise to
phylogenetically informative patterns in sequence data, this may not always
be so.
相似文献
73.
Definition of the inhibitory domain of smooth muscle myosin light chain kinase by site-directed mutagenesis 总被引:4,自引:0,他引:4
Site-directed mutagenesis of smooth muscle myosin light chain kinase was applied to define its autoinhibitory domain. Mutants were all initiated at Leu-447 but contained varying lengths of C-terminal sequence. Those containing the complete C-terminal sequence to Glu-972 possessed kinase activities that were calmodulin-dependent. Removal of the putative inhibitory domain by truncation to Thr-778 resulted in generation of a constitutively active (calmodulin-independent) species. Thus, the inhibitory domain lies to the C-terminal side of Thr-778. Truncation to Lys-793 and to Trp-800 also resulted in constitutively active mutants, although the specific activity of the latter was less than the other mutants. None of the truncated mutants bound calmodulin. For each mutant, the Km values with respect to ATP and to the 20,000-dalton light chain were similar to values obtained with the native enzyme. The presence of the inhibitory domain was detected by activation of kinase activity following limited proteolysis with trypsin. Using this procedure, it was determined that the inhibitory domain was manifest only in the mutant truncated to Trp-800 and was absent from that ending at Lys-793. These results indicate that a critical region of the inhibitory domain is contained within the sequence Tyr-794 to Trp-800. This region overlaps with the calmodulin-binding site for five residues. Our assignment of the inhibitory sequence is consistent with autoinhibition via a pseudosubstrate domain. 相似文献
74.
75.
CJ Cooksey 《Biotechnic & histochemistry》2017,92(5):309-314
The history of chemical investigations into the yellow components of turmeric can be traced from 1815. Although the major yellow component of turmeric, curcumin, often is represented as a 1,3-diketone in the solid state and in nonaqueous solution, it exists in the enol form. The struggle to identify the chemical structure of curcumin continued for nearly a century and was complicated by the difficult purification of curcumin and by the presence of two additional yellow components. Food remains the main use for turmeric (old spice); its use as a dye has diminished since the 19th century, but it may have pharmaceutical uses (new spice). 相似文献
76.
In Chlorella sorokiniana (211/8k), glucose-6 phosphate dehydrogenase (G6PDH—EC 1.1.1.49) activity is similar in both N-starved cells and nitrate-grown algae when expressed on a PCV basis. A single G6PDH isoform was purified from Chlorella cells grown under different nutrient conditions; the presence of a single G6PDH was confirmed by native gels stained for enzyme activity and by Western blots. The algal G6PDH is recognised only by antibodies raised against higher plants plastidic protein, but not by chloroplastic and cytosolic isoform-specific antisera. Purified G6PDH showed kinetic parameters similar to plastidic isoforms of higher plants, suggesting a different biochemical structure which would confer peculiar regulative properties to the algal G6PDH with respect to higher plants enzymes. The most remarkable property of algal G6PDH is represented by the response to NADPH inhibition. The algal enzyme is less sensitive to NADPH effects compared to higher plants G6PDH: KiNADPH is 103 μM for G6PDH from nitrogen-starved C. sorokiniana, similarly to root plastidic P2-G6PDH. In nitrate-grown C. sorokiniana the KiNADPH decreased to 48 μM, whereas other kinetic parameters remained unchanged. These results will allow further investigations in order to rule out possible modifications of the enzyme, and/or the expression of a different G6PDH isoform during nitrate assimilation. 相似文献
77.
Myriam Ferrara Gea Guerriero Manuela Cardi Sergio Esposito 《Extremophiles : life under extreme conditions》2013,17(1):53-62
Psychrophilic organisms have evolved a number of modifications of cellular structures to survive in the cold environment; among them it is worth noting an increased efficiency of enzymes at lower temperatures. Glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) was purified and characterised from the psychrophilic green alga Koliella antarctica (Trebouxiophyceae, Chlorophyta) from the Ross Sea (Antarctica). It was possible to isolate a single G6PDH using biochemical strategies; its maximum activity was measured at 35 °C, and the enzyme showed an E a of 39.6 kJ mol?1. This protein reacted with antibodies raised against higher plants plastidic isoforms. KaG6PDH showed peculiar kinetic properties, with a K iNADPH value lower than $ K_{{{\text{mNADP}}^{ + } }} $ . Notably, catalytic activity was inactivated in vitro by DTT and chloroplastic thioredoxin f. These biochemical properties of G6PDH are discussed with respect to higher plant G6PDHs and the adaptation of K. antarctica to polar low-temperature environment. 相似文献
78.
Sonja Melman Ellen NC Schoorel Carmen Dirksen Anneke Kwee Luc Smits Froukje de Boer Madelaine Jonkers Mallory D Woiski Ben Willem J Mol Johannes PR Doornbos Harry Visser Anjoke JM Huisjes Martina M Porath Friso MC Delemarre Simone MI Kuppens Robert Aardenburg Ivo MA Van Dooren Francis PJM Vrouenraets Frans TH Lim Gunilla Kleiverda Paulien CM van der Salm Karin de Boer Marko J Sikkema Jan G Nijhuis Rosella PMG Hermens Hubertina CJ Scheepers 《Implementation science : IS》2013,8(1):1-8
Background
Caesarean section (CS) rates are rising worldwide. In the Netherlands, the most significant rise is observed in healthy women with a singleton in vertex position between 37 and 42 weeks gestation, whereas it is doubtful whether an improved outcome for the mother or her child was obtained. It can be hypothesized that evidence-based guidelines on CS are not implemented sufficiently. Therefore, the present study has the following objectives: to develop quality indicators on the decision to perform a CS based on key recommendations from national and international guidelines; to use the quality indicators in order to gain insight into actual adherence of Dutch gynaecologists to guideline recommendations on the performance of a CS; to explore barriers and facilitators that have a direct effect on guideline application regarding CS; and to develop, execute, and evaluate a strategy in order to reduce the CS incidence for a similar neonatal outcome (based on the information gathered in the second and third objectives).Methods
An independent expert panel of Dutch gynaecologists and midwives will develop a set of quality indicators on the decision to perform a CS. These indicators will be used to measure current care in 20 hospitals with a population of 1,000 women who delivered by CS, and a random selection of 1,000 women who delivered vaginally in the same period. Furthermore, by interviewing healthcare professionals and patients, the barriers and facilitators that may influence the decision to perform a CS will be measured. Based on the results, a tailor-made implementation strategy will be developed and tested in a controlled before-and-after study in 12 hospitals (six intervention, six control hospitals) with regard to effectiveness, experiences, and costs.Discussion
This study will offer insight into the current CS care and into the hindering and facilitating factors influencing obstetrical policy on CS. Furthermore, it will allow definition of patient categories or situations in which a tailor-made implementation strategy will most likely be meaningful and cost effective, without negatively affecting the outcome for mother and child.Trial registration
http://www.clinicaltrials.gov: NCT01261676 相似文献79.
Using ontologies to describe mouse phenotypes 总被引:1,自引:1,他引:0
The mouse is an important model of human genetic disease. Describing phenotypes of mutant mice in a standard, structured manner that will facilitate data mining is a major challenge for bioinformatics. Here we describe a novel, compositional approach to this problem which combines core ontologies from a variety of sources. This produces a framework with greater flexibility, power and economy than previous approaches. We discuss some of the issues this approach raises. 相似文献
80.
Rings A, D and E of faradiol (1), and ring E of both arnidiol (10) and calenduladiol (4) have been subjected to various selective chemical manipulations to modify polarity, water affinity, H-bonding, sterics, and number of aromatic groups of these anti-inflammatory natural compounds. A total of 15 new and four known pentacyclic triterpenoids have been obtained in this way. Some 13 terpenoids were evaluated for their topical anti-inflammatory activities with respect to inhibition of croton oil induced ear oedema in mouse. Three derivatives of 1, the C(16) benzyl ether 15, the C(30) aldehyde 24, and the C(30) primary alcohol 25 showed significantly improved anti-inflammatory potencies, which is relevant for (future) structure-activity-relationship (SAR) studies. 相似文献