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排序方式: 共有311条查询结果,搜索用时 15 毫秒
1.
Role of Thidiazuron (TDZ) in inducing adventitious organogenesis in Pongamia was studied. TDZ at different concentrations (0, 0.45, 2.27, 4.54, 6.71, 9.08, 11.35, 13.12 and 22.71 μM) were used for induction of caulogenic bud formation in deembryonated cotyledon explants. Each cotyledon was cut into three segments and identified as proximal, middle and distal. Duration of TDZ exposure, influence of the segment and orientation of the explant were studied. TDZ at 11.35 μM concentration was optimum for the induction of shoots and rapid elongation. Shoots induced at higher concentration elongated after several passages in growth regulator free medium, thereby extending the period of differentiation. Exposure of the explant for 20 days yielded more number of buds than 10 days. Proximal segment of the cotyledon was more responsive. Contact of abaxial surface in the medium was more effective and generated more buds than the adaxial side. Buds differentiated and elongated on transfer to MS basal medium for 8–12 passages of 15 days each. Rooting and elongation of shoots was achieved in charcoal supplemented half-strength MS medium. Rooted plantlets survived on transfer to sand soil mixture. The plants were hardened and transferred to green house. This is the first report on in vitro regeneration of Pongamia pinnata via adventitious organogenesis using TDZ. This protocol may find application in studies in genetic transformation, isolation of somaclonal variants and in induction of mutants. It also provides a system to study the inhibitory role of TDZ on shoot differentiation.  相似文献   
2.
This paper describes two complexes containing N,N-dimethylproflavine and the dinucleoside monophosphate, 5-iodocytidylyl (3'-5') guanosine (iodoCpG). The first complex is triclinic, space group P1, with unit cell dimensions a = 11.78 A, b = 14.55 A, c = 15.50 A, alpha = 89.2 degrees, beta = 86.2 degrees, gamma = 96.4 degrees. The second complex is monoclinic, space group P21, with a = 14.20 A. b = 19.00 A, c = 20.73 A, beta = 103.6 degrees. Both structures have been solved to atomic resolution and refined by Fourier and least squares methods. The first structure has been refined anisotropically to a residual of 0.09 on 5,025 observed reflections using block diagonal least squares, while the second structure has been refined anisotropically to a residual of 0.13 on 2,888 reflections with full matrix least squares. The asymmetric unit in both structures contains two dimethylproflavine molecules and two iodoCpG molecules; the first structure has 16 water molecules (a total of 134 non-hydrogen atoms), while the second structure has 18 water molecules (a total of 136 non-hydrogen atoms). Both structures demonstrate intercalation of dimethylproflavine between base-paired iodoCpG dimers. In addition, dimethylproflavine molecules stack on either side of the intercalated duplex, being related by a unit cell translation along b and a axes, respectively. The basic structural feature of the sugar-phosphate chains accompanying dimethylproflavine intercalation in both structures is the mixed sugar puckering pattern: C3' endo (3'-5') C2' endo. This same structural information is again demonstrated in the accompanying paper, which describes a complex containing dimethylproflavine with deoxyribo-CpG. Similar information has already appeared for other "simple" intercalators such as ethidium, acridine orange, ellipticine, 9-aminoacridine, N-methyl-tetramethylphenanthrolinium and terpyridine platinum. "Complex" intercalators, however, such as proflavine and daunomycin, have given different structural information in model studies. We discuss the possible reasons for these differences in this paper and in the accompanying paper.  相似文献   
3.
The lubricating properties of human submandibular-sublingual salivary fractions were examined using a servohydraulic model of mandibular movement. Fractions containing statherin exhibited a strong tendency to boundary lubrication. The lubricity of purified statherin was confirmed and compared to the amphipathic molecules gramacidin S and sodium dodecyl sulfate. Contact angle measurements of statherin paralleled the other amphipathic molecules. The helical content of statherin increased in trifluoroethanol indicating the presence of amphipathic helical regions. CD studies and hydrophobic moment calculations indicated that statherin adopts an amphipathic helical conformation at the N-terminus. An energy-minimized model of the polar N-terminal residues 1-15 suggested that this domain could be positioned in space to interact with a hydroxyapatite substrate. These data imply that under appropriate conditions statherin may display an amphipathic nature which enables it to function as a boundary lubricant on enamel.  相似文献   
4.
The conformation of the acyclic biscystine peptide S,S'-bis(Boc-Cys-Ala-OMe) has been studied in the solid state by x-ray diffraction, and in solution by 1H- and 13C-nmr, ir, and CD methods. The peptide molecule has a twofold rotation symmetry and adopts an intramolecular antiparallel beta-sheet structure in the solid state. The two antiparallel extended strands are stabilized by two hydrogen bonds between the Boc CO and Ala NH groups [N...O 2.964 (3) A, O...HN 2.11 (3) A, and NH...O angle 162 (3) degrees]. The disulfide bridge has a right-handed conformation with the torsion angle C beta SSC beta = 95.8 (2) degrees. In solution the presence of a twofold rotation symmetry in the molecule is evident from the 1H- and 13C-nmr spectra. 1H-nmr studies, using solvent and temperature dependencies of NH chemical shifts, paramagnetic radical induced line broadening, and rate of deuterium-hydrogen exchange effects on NH resonances, suggest that Ala NH is solvent shielded and intramolecularly hydrogen bonded in CDCl3 and in (CD3)2SO. Nuclear Overhauser effects observed between Cys C alpha H and Ala NH protons and ir studies provide evidence of the occurrence of antiparallel beta-sheet structure in these solvents. The CD spectra of the peptide in organic solvents are characteristic of those observed for cystine peptides that have been shown to adopt antiparallel beta-sheet structures.  相似文献   
5.

Introduction

The development of effective treatments for osteoarthritis (OA) has been hampered by a poor understanding of OA at the cellular and molecular levels. Emerging as a disease of the ''whole joint’, the importance of the biochemical contribution of various tissues, including synovium, bone and articular cartilage, has become increasingly significant. Bathing the entire joint structure, the proteomic analysis of synovial fluid (SF) from osteoarthritic shoulders offers a valuable ''snapshot’ of the biologic environment throughout disease progression. The purpose of this study was to identify differentially expressed proteins in early and late shoulder osteoarthritic SF in comparison to healthy SF.

Methods

A quantitative 18O labeling proteomic approach was employed to identify the dysregulated SF proteins in early (n = 5) and late (n = 4) OA patients compared to control individuals (n = 5). In addition, ELISA was used to quantify six pro-inflammatory and two anti-inflammatory cytokines.

Results

Key results include a greater relative abundance of proteins related to the complement system and the extracellular matrix in SF from both early and late OA. Pathway analyses suggests dysregulation of the acute phase response, liver x receptor/retinoid x receptor (LXR/RXR), complement system and coagulation pathways in both early and late OA. The network related to lipid metabolism was down-regulated in both early and late OA. Inflammatory cytokines including interleukin (IL) 6, IL 8 and IL 18 were up-regulated in early and late OA.

Conclusions

The results suggest a dysregulation of wound repair pathways in shoulder OA contributing to the presence of a ''chronic wound’ that progresses irreversibly from early to later stages of OA. Protease inhibitors were downregulated in late OA suggesting uncontrolled proteolytic activity occurring in late OA. These results contribute to the theory that protease inhibitors represent promising therapeutic agents which could limit proteolytic activity that ultimately leads to cartilage destruction.  相似文献   
6.

Background

The ciliary body is the circumferential muscular tissue located just behind the iris in the anterior chamber of the eye. It plays a pivotal role in the production of aqueous humor, maintenance of the lens zonules and accommodation by changing the shape of the crystalline lens. The ciliary body is the major target of drugs against glaucoma as its inhibition leads to a drop in intraocular pressure. A molecular study of the ciliary body could provide a better understanding about the pathophysiological processes that occur in glaucoma. Thus far, no large-scale proteomic investigation has been reported for the human ciliary body.

Results

In this study, we have carried out an in-depth LC-MS/MS-based proteomic analysis of normal human ciliary body and have identified 2,815 proteins. We identified a number of proteins that were previously not described in the ciliary body including importin 5 (IPO5), atlastin-2 (ATL2), B-cell receptor associated protein 29 (BCAP29), basigin (BSG), calpain-1 (CAPN1), copine 6 (CPNE6), fibulin 1 (FBLN1) and galectin 1 (LGALS1). We compared the plasma proteome with the ciliary body proteome and found that the large majority of proteins in the ciliary body were also detectable in the plasma while 896 proteins were unique to the ciliary body. We also classified proteins using pathway enrichment analysis and found most of proteins associated with ubiquitin pathway, EIF2 signaling, glycolysis and gluconeogenesis.

Conclusions

More than 95% of the identified proteins have not been previously described in the ciliary body proteome. This is the largest catalogue of proteins reported thus far in the ciliary body that should provide new insights into our understanding of the factors involved in maintaining the secretion of aqueous humor. The identification of these proteins will aid in understanding various eye diseases of the anterior segment such as glaucoma and presbyopia.  相似文献   
7.
Bacterial vaginosis (BV) is a highly prevalent condition associated with adverse health outcomes. Gram stain analysis of vaginal fluid is the standard for confirming the diagnosis of BV, wherein abundances of key bacterial morphotypes are assessed. These Lactobacillus, Gardnerella, Bacteroides, and Mobiluncus morphotypes were originally linked to particular bacterial species through cultivation studies, but no studies have systematically investigated associations between uncultivated bacteria detected by molecular methods and Gram stain findings. In this study, 16S-rRNA PCR/pyrosequencing was used to examine associations between vaginal bacteria and bacterial morphotypes in 220 women with and without BV. Species-specific quantitative PCR (qPCR) and fluorescence in Situ hybridization (FISH) methods were used to document concentrations of two bacteria with curved rod morphologies: Mobiluncus and the fastidious BV-associated bacterium-1 (BVAB1). Rank abundance of vaginal bacteria in samples with evidence of curved gram-negative rods showed that BVAB1 was dominant (26.1%), while Mobiluncus was rare (0.2% of sequence reads). BVAB1 sequence reads were associated with Mobiluncus morphotypes (p<0.001). Among women with curved rods, mean concentration of BVAB1 DNA was 2 log units greater than Mobiluncus (p<0.001) using species-specific quantitative PCR. FISH analyses revealed that mean number of BVAB1 cells was 2 log units greater than Mobiluncus cells in women with highest Nugent score (p<0.001). Prevotella and Porphyromonas spp. were significantly associated with the “Bacteroides morphotype,” whereas Bacteroides species were rare. Gram-negative rods designated Mobiluncus morphotypes on Gram stain are more likely BVAB1. These findings provide a clearer picture of the bacteria associated with morphotypes on vaginal Gram stain.  相似文献   
8.
To elucidate how human DNA polymerase β (pol β) discriminates dATP from dCTP when processing 8-oxoguanine (8-oxoG), we analyze a series of dynamics simulations before and after the chemical step with dATP and dCTP opposite an 8-oxoG template started from partially open complexes of pol β. Analyses reveal that the thumb closing of pol β before chemistry is hampered when the incorrect nucleotide dATP is bound opposite 8-oxoG; the unfavorable interaction between active-site residue Tyr271 and dATP that causes an anti to syn change in the 8-oxoG (syn):dATP complex explains this slow motion, in contrast to the 8-oxoG (anti):dCTP system. Such differences in conformational pathways before chemistry for mismatched versus matched complexes help explain the preference for correct insertion across 8-oxoG by pol β. Together with reference studies with a nonlesioned G template, we propose that 8-oxoG leads to lower efficiency in pol β's incorporation of dCTP compared with G by affecting the requisite active-site geometry for the chemical reaction before chemistry. Furthermore, because the active site is far from ready for the chemical reaction after partial closing or even full thumb closing, we suggest that pol β is tightly controlled not only by the chemical step but also by a closely related requirement for subtle active-site rearrangements after thumb movement but before chemistry.  相似文献   
9.
An in vitro propagation system for Artemisia vulgaris L., a traditional medicinal plant, has been developed. The best organogenic response, including adventitious shoot number and elongation, was obtained when hypocotyl segments were cultured onto MS medium supplemented with 4.54 μM TDZ (N-phenyl-N′-(1,2,3-thidiazol-yl) urea). Up to 28 shoots formed per explant for an optimal duration of exposure of 48 days. Regenerated shoots formed roots when subcultured onto a medium containing 8.56 μM IAA (indole-3-acetic acid). Healthy plantlets were transferred to a garden soil:farmyard soil:sand (2:1:1) mixture for acclimatization, which was successful, and subsequent maturity was achieved under greenhouse conditions over a six-month period. The survival rate of the plantlets varied under acclimatization. The regeneration protocol developed in this study provides a basis for germplasm conservation and for further investigation of medicinally active constituents of A. vulgaris. This optimized protocol has been successfully employed for genetic transformation studies in A. vulgaris, which are currently underway in our laboratory.  相似文献   
10.
Limitations of available indicators [such as6-methoxy-N-(3-sulfopropyl)quinolinium(SPQ)] for measurement of intracellular Cl are their relatively dimfluorescence and need for ultraviolet excitation. A series oflong-wavelength polar fluorophores was screened to identify compoundswith Cl and/orI sensitivity, brightfluorescence, low toxicity, uniform loading of cytoplasm with minimalleakage, and chemical stability in cells. The best compound found was7-(-D-ribofuranosylamino)-pyrido[2,1-h]-pteridin-11-ium-5-olate (LZQ). LZQ is brightly fluorescent with excitation andemission maxima at 400-470 and 490-560 nm, molar extinction11,100 M1 · cm1(424 nm), and quantum yield 0.53. LZQ fluorescence is quenched byI by a collisionalmechanism (Stern-Volmer constant 60 M1) and is not affectedby other halides, nitrate, cations, or pH changes (pH 5-8). AfterLZQ loading into cytoplasm by hypotonic shock or overnight incubation,LZQ remained trapped in cells (leakage <3%/h). LZQ stained cytoplasmuniformly, remained chemically inert, did not bind to cytoplasmiccomponents, and was photobleached by <1% during 1 h of continuousillumination. Cytoplasmic LZQ fluorescence was quenched selectively byI (50% quenching at 38 mMI). LZQ was used tomeasure forskolin-stimulatedI/ClandI/NO3exchange in cystic fibrosis transmembrane conductance regulator(CFTR)-expressing cell lines by fluorescence microscopy and microplatereader instrumentation using 96-well plates. The substantially improvedoptical and cellular properties of LZQ over existing indicators shouldpermit the quantitative analysis of CFTR function in gene deliverytrials and high-throughput screening of compounds for correction of thecystic fibrosis phenotype.

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