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71.
Limatola C Massa V Lauro C Catalano M Giovanetti A Nuccitelli S Spinedi A 《FEBS letters》2007,581(14):2641-2646
Chemotaxis induction is a major effect evoked by stimulation of the chemokine receptor CXCR4 with its sole ligand CXCL12. We now report that treatment of CHP-100 human neuroepithelioma cells with the glucosylceramide synthase (GCS) inhibitor DL-threo-1-phenyl-2-hexadecanoylamino-3-pyrrolidino-1-propanol inhibits CXCR4-dependent chemotaxis. We provide evidence that the phenomenon is not due to unspecific effects of the inhibitor employed and that inhibition of GCS neither affects total or plasmamembrane CXCR4 expression, nor CXCL12-induced Ca(2+) mobilization. The effects of the GCS inhibitor on impairment of CXCL12-induced cell migration temporally correlated with a pronounced downregulation of neutral glycosphingolipids, particularly glucosylceramide, and with a delayed and more moderate downregulation of gangliosides; moreover, exogenously administered glycosphingolipids allowed resumption of CXCR4-dependent chemotaxis. Altogether our results provide evidence, for the first time, for a role glycosphingolipids in sustaining CXCL12-induced cell migration. 相似文献
72.
EDTA-induced Membrane Fluidization and Destabilization: Biophysical Studies on Artificial Lipid Membranes 总被引:5,自引:0,他引:5
Prachayasittikul V Isarankura-Na-Ayudhya C Tantimongcolwat T Nantasenamat C Galla HJ 《Acta biochimica et biophysica Sinica》2007,39(11):901-913
The molecular mechanism of ethylenediaminetetraacetic acid (EDTA)-induced membrane destabilization has been studied using a combination of four biophysical techniques on artificial lipid membranes. Data from Langmuir film balance and epifluorescence microscopy revealed the fluidization and expansion effect of EDTA on phase behavior of monolayers of either 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or mixtures of DPPC and metal-chelating lipids, such as N^a,N^a-Bis[carboxymethyl]-N^ε [(dioctadecylamino)succinyl]-L-lysine or 1,2-dioleoyl-sn-glycero-3-[N-(5-amino- 1 -carboxypentyl iminodiacetic acid) succinyl]. A plausible explanation could be drawn from the electrostatic interaction between negatively charged groups of EDTA and the positively charged choline head group of DPPC. Intercalation of EDTA into the lipid membrane induced membrane curvature as elucidated by atomic force microscopy. Growth in size and shape of the membrane protrusion was found to be time-dependent upon exposure to EDTA. Further loss of material from the lipid membrane surface was monitored in real time using a quartz crystal microbalance. This indicates membrane restabilization by exclusion of the protrusions from the surface. Loss of lipid components facilitates membrane instability, leading to membrane permeabilization and lysis. 相似文献
73.
74.
Alzheimer’s disease (AD) is a multifaceted neurodegenerative disorder affecting the elderly people. For the AD treatment, there is inefficiency in the existing medication, as these drugs reduce only the symptoms of the disease. Since multiple pathological proteins are involved in the development of AD, searching for a single molecule targeting multiple AD proteins will be a new strategy for the management of AD. In view of this, the present study was designed to synthesize and evaluate the multifunctional neuroprotective ability of the sesquiterpene glycoside α-bisabolol β-D-fucopyranoside (ABFP) against multiple targets like acetylcholinesterase, oxidative stress and β-amyloid peptide aggregation induced cytotoxicity. In silico computational docking and simulation studies of ABFP with acetylcholinesterase (AChE) showed that it can interact with Asp74 and Thr75 residues of the enzyme. The in vitro studies showed that the compound possess significant ability to inhibit the AChE enzyme apart from exhibiting antioxidant, anti-aggregation and disaggregation properties. In addition, molecular dynamics simulation studies proved that the interacting residue between Aβ peptide and ABFP was found to be involved in Leu34 and Ile31. Furthermore, the compound was able to protect the Neuro2 a cells against Aβ25-35 peptide induced toxicity. Overall, the present study evidently proved ABFP as a neuroprotective agent, which might act as a multi-target compound for the treatment of Alzheimer’s disease. 相似文献
75.
In the course of the present work CaF2 epitaxialfilms were grown on Si(111) substrates by means ofMBE. The Si substrates were chemically cleaned priorto insertion into the system. The final volatile oxidewas desorbed in situ by heating to 850. CaF2 was evaporated from aKnudsen-type cell by use of a graphite crucible, whilethe growth temperature was held at 650 .RHEED (Reflection High Energy Electron Diffraction)has been used to monitor the film growth in situand to study the epitaxial quality. Also we have usedthe MeV He+ RBS channeling technique to look atdefects and to measure strain in the CaF2 layer.Usually good crystallographic properties are achievedunder optimum growth conditions, with values ofmin < 5%. Electrical properties aremeasured by use of a special MIS structure. 相似文献
76.
UNC-60B, an ADF/cofilin family protein, is required for proper assembly of actin into myofibrils in Caenorhabditis elegans body wall muscle
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The Caenorhabditis elegans unc-60 gene encodes two functionally distinct isoforms of ADF/cofilin that are implicated in myofibril assembly. Here, we show that one of the gene products, UNC-60B, is specifically required for proper assembly of actin into myofibrils. We found that all homozygous viable unc-60 mutations resided in the unc-60B coding region, indicating that UNC-60B is responsible for the Unc-60 phenotype. Wild-type UNC-60B had F-actin binding, partial actin depolymerizing, and weak F-actin severing activities in vitro. However, mutations in UNC-60B caused various alterations in these activities. Three missense mutations resulted in weaker F-actin binding and actin depolymerizing activities and complete loss of severing activity. The r398 mutation truncated three residues from the COOH terminus and resulted in the loss of severing activity and greater actin depolymerizing activity. The s1307 mutation in a putative actin-binding helix caused greater activity in actin-depolymerizing and severing. Using a specific antibody for UNC-60B, we found varying protein levels of UNC-60B in mutant animals, and that UNC-60B was expressed in embryonic muscles. Regardless of these various molecular phenotypes, actin was not properly assembled into embryonic myofibrils in all unc-60 mutants to similar extents. We conclude that precise control of actin filament dynamics by UNC-60B is required for proper integration of actin into myofibrils. 相似文献
77.
Numerical simulations of surface plasmon resonance system for monitoring DNA hybridization and detecting protein-lipid film interactions 总被引:1,自引:0,他引:1
This paper presents a simple method to extract information about thin organic films from surface plasmon resonance (SPR)
spectra. From numerical simulations it was found that a shift (Δθ
SPR) of an absorption peak in the SPR spectrum was directly proportional to the product of the thin organic film thickness and
the refractive index difference between the thin organic film and a buffer soaking the sample. It was also found that Δθ
SPR was not sensitive to the thin organic film support of a gold film and a glass cover slip. Relationships between Δθ
SPR and distributions of macromolecule structures, in the thin organic films were theoretically established. Formulae were derived
for a homemade SPR system to calculate length, transverse area, density and surface concentration of macromolecules in the
thin organic film. The validity of these treatments was checked by precisely measuring the size of a single distearoylphosphatidylcholine
molecule on a gold-supported phospholipid film; by quantitatively monitoring hybridization of synthesized oligonucleotides
strands based on a biotin/avidin system; and by quantitatively detecting the steric hindrance of rabbit C-reactive protein
specifically bound to phospholipid monolayers composed of synthesized lipids.
Received: 4 May 1998 / Revised version: 27 July 1998 / Accepted: 27 August 1998 相似文献
78.
AIMS: To investigate the dynamics of binary culture biofilm formation through use of both the Sorbarod model of biofilm growth and the constant depth film fermenter (CDFF). METHODS AND RESULTS: Pseudo steady-state biofilm cultures of laboratory and clinical strains of Pseudomonas aeruginosa, selected on the basis of their ability to produce a Burkholderia cepacia growth-inhibitory substance, were established on Sorbarod filters and challenged with corresponding planktonic grown cultures of B. cepacia. Reverse challenges were also conducted. Both B. cepacia and P. aeruginosa were able to form steady-state monoculture biofilms after 48 h growth. When steady-state biofilms of B. cepacia NTCT 10661 were challenged with planktonically grown P. aeruginosa PAO1 known to produce a B. cepacia growth-inhibitory substance, the immigrant population was rapidly and almost completely bound to the biofilm, displacing B. cepacia. By contrast, established biofilms of P. aeruginosa PAO1 resisted immigration of B. cepacia 10661. Similar experiments conducted with a nongrowth inhibitory substance producing clinical pairing of P. aeruginosa 313113 and B. cepacia 313113 led to the formation of stable, mixed biofilm populations in both instances. Moreover, co-inoculation with these clinical isolates resulted in a stable, mixed steady-state biofilm. Similar observations were made for biofilms generated in CDFFs. In such instances following pan-swapping between two monoculture CDFFs, B. cepacia 313113 was able to integrate into an established P. aeruginosa 313113 biofilm to form a stable binary biofilm. CONCLUSIONS: Establishment of a mixed species community follows a specific sequence of inoculation that may either be due to some degree of match between co-colonizers or that P. aeruginosa predisposes uncolonized sections of the surface to permit B. cepacia colonization. SIGNIFICANCE AND IMPACT OF THE STUDY: Colonization of a surface with one bacterial species confers colonization resistance towards other species. Disinfection of a surface might well increase the probability of pathogen harbourage. 相似文献
79.
The purpose of this study was to evaluate the nature of film formation on tablets with different compositions, using confocal
laser scanning microscopy (CLSM), and to measure film adhesion via the application of a novel “magnet probe test”. Three excipients,
microcrystalline cellulose (MCC), spray-dried lactose monohydrate, and dibasic calcium phosphate dihydrate, were individually
blended with 0.5% magnesium stearate, as a lubricant, and 2.5% tetracycline HCl, as a fluorescent marker, and were compressed
using a Carver press. Tablets were coated with a solution consisting of 7% hydroxypropyl methylcellulose (HPMC) phthalate
(HP-55), and 0.5% cetyl alcohl in acetone and isopropanol (11:9). The nature of polymer interaction with the tablets and coating
was evaluated using CLSM and a designed magnet probe test. CLSM images clearly showed coating efficiency, thickness, and uniformity
of film formation, and the extent of drug migration into the film at the coating interfaces of tablets. Among the excipients,
MCC demonstrated the best interface for both film formation and uniformity in thickness relative to lactose monohydrate and
dibasic calcium phosphate dihydrate. The detachment force of the coating layers from the tablet surfaces, as measured with
the developed magnet probe test, was in the order of MCC>lactose monohydrate>dibasic calcium phosphate dihydrate. It was also
shown that the designed magnet probe test provides reliable and reproducible results when used for measurement of film adhesion
and bonding strength. 相似文献
80.
Shimizu M Kobayashi K Morii H Mitsui K Knoll W Nagamune T 《Biochemical and biophysical research communications》2003,310(2):606-611
In order to analyze the secondary structures of protein molecules adsorbed on gold surfaces, circular dichroism (CD) spectra were measured and the secondary structure contents of protein ultra-thin films were estimated quantitatively. A disulfide group was introduced to cytochrome b(562) (cyt.b562), which is a water-soluble b-type heme protein. The cyt.b562 molecules self-assembled to form an ultra-thin protein film both on a gold substrate modified with 2,2(')-dithiodiacetic acid and on a bare gold surface. CD measurements were carried out both in solution and in air, and these results were compared. The protein denaturation was partially prevented, not only in solution but also in air, by both the modification of the substrate and the introduction of the anchor group to the protein molecule. The secondary structure contents of ultra-thin protein films on flat gold surfaces were observed for the first time both in solution and in air by CD spectra. 相似文献