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1.
Vyacheslav L. L'vov Irina K. Verner Larisa Yu. Musina Alexander V. Rodionov Anatoly V. Ignatenko Alexander S. Shashkov 《Archives of microbiology》1992,157(2):131-134
On the basis of chemical and NMR data the partial structure of lipid A from lipooligosaccharide (LOS) of Neisseria meningitidis group B, strain BC5S No 125 was established. Lipid A consisted of disaccharide 2-deoxy-6-O-[2-deoxy-2-(3-hydroxytetradecanoylamino)--gluco-pyranosyl]-2-(3-hydroxytetradecanoylamino)--glucopyranose carrying the -(2-aminoethyl)pyrophosphate residue at 0–4 and the pyrophosphate or phosphate residue at 0–1. On hydrolysis of the acidic form of LOS with 1% acetic acid the substituent at 0–1 was practically completely removed whereas that at 0–4 was stable. The analogous hydrolysis of the Mg-salt of LOS was accompanied by splitting off the pyrophosphate linkage in the substituent at 0–4. Hydrolysis of LOS at pH 4.5 in the presence of SDS led mainly to a lipid A preparation retaining both pyrophosphate residues.Abbreviations KDO
2-keto-3-deoxyoctulosonic acid
- LA-I, LA-II
preparations of lipid A
- LOS
lipooligosaccharide
- LOS-H+
the acidic form of LOS
- OS
oligosaccharide
- TLC
thin-layer chromatography
- GLC-MS
gas-liquid chromatography/mass spectrometry 相似文献
2.
For analytical purposes bioluminescence can be used in three main ways: 1. luminescence measurement of bioluminescent system components isolated in vitro; 2. determination of luminous organisms' reaction to the in vivo test-action; 3. measurement of bioluminescence in marine ecological systems. The majority of the reports of this Symposium are dealing with the first two topics. The aim of our presentation is to draw attention to the third one. The possibilities of bioluminescent analysis are wider than its traditional scheme of applications in the laboratory, when the emitting system is withdrawn from a native source and is placed in a cuvette of the light measuring device. The reverse scheme is also possible, i.e. the device can be introduced into light emitting system such as a marine biocenosis–the community of the sea inhabitants–where we obtain a highly sensitive and rapid means of gaining the information on the vital activity of marine ecosystems, i.e. their spatial structure, rhythms, man's influence upon them, etc. The present communication will consider the possibilities of this form of bioluminescent analysis. 相似文献
3.
The use of high-spectral-resolution radiometer data for detection of low chlorophyll concentrations in Lake Kinneret 总被引:2,自引:0,他引:2
Gitelson A.; Mayo M.; Yacobi Y.Z.; Parparov A.; Berman T. 《Journal of plankton research》1994,16(8):993-1002
Chlorophyll distribution in Lake Kinneret was estimated in aperiod of low chlorophyll-a concentrations (37 mg m3)using remotely sensed data. The data set included high-spectral-resolutionradiometric measurements in the range 400750 nm, chlorophylland suspended matter concentrations, Secchi disk transparencyand vertical attenuation coefficients at 20 stations. The spectroradiometricdata were used to create the algorithms suitable for quantitativedetermination of chlorophyll content. The present paper presentsexperimental field evidence showing that fluorescence can besuccessfully used for remote monitoring of chlorophyll-a content(with an estimation error <0.5 mg m3) in productiveinland waters with a background of variable and relatively highsuspended matter concentration. 相似文献
4.
Eva Kot Robin Miller-Catchpole Anatoly Bezkorovainy 《Biological trace element research》1993,38(1):1-12
Protoplasts ofBifidobacterium thermophilum were prepared by a combination of lysozyme and protease digestion, and ferrous iron uptake studies were carried out. Little,
if any, iron was internalized by the protoplasts, although large amounts of iron were bound to the protoplast surface. This
binding was much greater than that of intact cells, which prefer to internalize iron by an energy-dependent process. It was
also found that the binding of iron by protoplasts of cells grown in an iron-deficient medium was much more extensive than
that of cells grown in an iron-sufficient medium. Soluble and particulate fractions of protoplasts were prepared by grinding
them in a glass homogenizer, and the particulate fraction was also subjected to iron binding studies. The amount of iron bound
was the same as that in intact protoplasts, indicating that the particulate fraction membrane fragments bound iron on their
outer surface only. Nevertheless, when iron-preloaded cells were protoplasted and their surface cleared of iron, their particulate
fraction contained considerable amounts of iron, indicating that the inner surface of the membranes is capable of binding
iron as long as the cell is intact. The amount of iron so bound was dose-dependent on the amount of iron entering the cell.
The failure of the outer and inner surface iron pools to mix was confirmed by the fact that when iron-preloaded protoplasts
were incubated with additional iron, only the latter (surface-bound) was elutable with nonradioactive 2 mM FeSO4. It is concluded that increasing bifidobacterial iron load increases the amount of iron bound to the inner surface of the
membrane; the procedure, which is effective in forming bifidobacterial protoplasts, destroys their iron transport mechanism
while uncovering surface iron-binding sites; and that such iron-binding sites may be of significance in the cellular iron
metabolism processes. 相似文献
5.
Beata Bartodziejska Joanna Radziejewska-Lebrecht Maria Lipinska Yuriy A. Knirel Leonid O. Kononov Anatoly Y. Chernyak Hubert Mayer Antoni Rozalski 《FEMS immunology and medical microbiology》1996,13(2):113-121
Abstract In DOC-PAGE, lipopolysaccharide (LPS) of Proteus mirabilis R14/1959 (Rb-type) mutant showed a ladder-like migration pattern indicating the presence of a high molecular weight polysaccharide chain. The isolated polysaccharide, called T-antigen because of similarity with the T1 chain of Salmonella friedenau LPS, contained d -glucose, d -galacturonic acid ( d -GalA), and d -GlcNAc in molar ratios 2:1:1 and was structurally different from the O-antigen of the parental S-strain P. mirabilis S1959 but identical to the O-antigen of another S-strain Proteus penneri 42. The importance of a d -GalA( l -Lys)-containing epitope, most likely present in the core region of LPS, and of GalA present in the T-antigen chain in manifesting the serological specificity of P. mirabilis R14/1959 were revealed using rabbit polyclonal homologous and heterologous R- and O-specific antisera and the appropriate antigens, including synthetic antigens which represent partial structures of various Proteus LPS. 相似文献
6.
Andrei G. Pakhomov Boris V. Dubovick Igor G. Degtyariov Anatoly N. Pronkevich 《Bioelectromagnetics》1995,16(4):250-254
The combined effects of microwave radiation and some drugs were studied in an isolated frog auricle preparation. The experiments established that exposure to pulse-modulated 915 MHz microwaves for up to 40 min had no effect on either the rate or the amplitude of spontaneous auricle twitches, unless the average absorbed power was high enough to produce preparation heating. Treatment of the preparation with saline containing (0.6–3.0) 10?5 M of propranolol or (0.5–1.5) 10?7 M of atropine altered neither its pacemaker nor its contractile functions; these drugs also had no effect when they were combined with nonthermal microwave irradiation. Caffeine (1 mM) strongly increased the average heart power, which was calculated as the product of twitch rate and amplitude. The caffeine effect appeared to be significantly augmented (by about 15%, P<0.02) under exposure to burst-type pulsed microwaves (pulse width, 1.5 msec; pause, 2.5 msec; 8 pulses/burst, 16 bursts/s; average SAR, 8–10 W/kg). By itself, this modulation was not effective; the heating of the preparation and saline during exposure was approximately 0.1°C, which could not account for the detected changes. The experimental results demonstrate that caffeine treatment increases the microwave sensitivity of the frog auricle preparation and reveals primarily subthreshold, nonthermal microwave effect. © 1995 Wiley-Liss, Inc. 相似文献
7.
Emeran A. Mayer Anatoly Kodner Xiao Ping Sun Jonathan Wilkes David Scott George Sachs 《The Journal of membrane biology》1992,125(2):107-118
Summary Intracellular calcium [Ca2+]
i
measurements in cell suspension of gastrointestinal myocytes have suggested a single [Ca2+]
i
transient followed by a steady-state increase as the characteristic [Ca2+]
i
response of these cells. In the present study, we used digital video imaging techniques in freshly dispersed myocytes from the rabbit colon, to characterize the spatiotemporal pattern of the [Ca2+]
i
signal in single cells. The distribution of [Ca2+]
i
in resting and stimulated cells was nonhomogeneous, with gradients of high [Ca2+]
i
present in the subplasmalemmal space and in one cell pole. [Ca2+]
i
gradients within these regions were not constant but showed temporal changes in the form of [Ca2+]
i
oscillations and spatial changes in the form of [Ca2+]
i
waves. [Ca2+]
i
oscillations in unstimulated cells (n = 60) were independent of extracellular [Ca2+] and had a mean frequency of 12.6 +1.1 oscillations per min. The baseline [Ca2+], was 171 ± 13 nm and the mean oscillation amplitude was 194 ± 12 nm. Generation of [Ca2+]
i
waves was also independent of influx of extracellular Ca2+. [Ca2+]
i
waves originated in one cell pole and were visualized as propagation mostly along the subplasmalemmal space or occasionally throughout the cytoplasm. The mean velocity was 23 +3 m per sec (n = 6). Increases of [Ca2+]
i
induced by different agonists were encoded into changes of baseline [Ca2+]
i
and the amplitude of oscillations, but not into their frequency. The observed spatiotemporal pattern of [Ca2+]
i
regulation may be the underlying mechanism for slow wave generation and propagation in this tissue. These findings are consistent with a [Ca2+]
i
regulation whereby cell regulators modulate the spatiotemporal pattern of intracellularly generated [Ca2+]
i
oscillations.The authors thank Debbie Anderson for excellent technical assistance with the electron microscopy and Dr. M. Regoli for providing the NK-1 agonist [Sar9,Met(O2)11]-SP. This work was supported by National Institutes of Health Grants DK 40919 and DK 40675 and Veterans Administration Grant SMI. 相似文献
8.
Tao Ke Filipe Marques Gonçalves Cinara Ludvig Gonçalves Alessandra Antunes dos Santos João B.T. Rocha Marcelo Farina Anatoly Skalny Aristidis Tsatsakis Aaron B. Bowman Michael Aschner 《生物化学与生物物理学报:疾病的分子基础》2019,1865(8):2068-2081
Mercury (Hg) exposure remains a major public health concern due to its widespread distribution in the environment. Organic mercurials, such as MeHg, have been extensively investigated especially because of their congenital effects. In this context, studies on the molecular mechanism of MeHg-induced neurotoxicity are pivotal to the understanding of its toxic effects and the development of preventive measures. Post-translational modifications (PTMs) of proteins, such as phosphorylation, ubiquitination, and acetylation are essential for the proper function of proteins and play important roles in the regulation of cellular homeostasis. The rapid and transient nature of many PTMs allows efficient signal transduction in response to stress. This review summarizes the current knowledge of PTMs in MeHg-induced neurotoxicity, including the most commonly PTMs, as well as PTMs induced by oxidative stress and PTMs of antioxidant proteins. Though PTMs represent an important molecular mechanism for maintaining cellular homeostasis and are involved in the neurotoxic effects of MeHg, we are far from understanding the complete picture on their role, and further research is warranted to increase our knowledge of PTMs in MeHg-induced neurotoxicity. 相似文献
9.
Anatoly D. Shutalev Valeriy E. Zavodnik Galina V. Gurskaya 《Nucleosides, nucleotides & nucleic acids》2013,32(10-12):1831-1846
Abstract Acid catalysed transformations of (6S)-6,5′-anhydro-6-hydroxy-1-(2′,3′-O-isopropylidene-β-D-ribofuranosyl)hexahydropyrimidine-2-thione are studied. (6R)-6,2′-anhydro-6-hydroxy-1-(α-D-ribofuranosyl)hexahydropyrimidine-2-thione was formed as a thermodynamically stable product. Two intermediates, (6S)-6,5′-anhydro-6-hydroxy-1-(β-D-ribofuranosyl)hexahydropyrimidine-2-thione and 6-hydroxy-1-(D-ribosyl)hexahydropyrimidine-2-thione and products of cleavage of glycosidic bond were identified in the reaction mixtures. Results of X-ray structural determination of the synthesised nucleosides are presented. 相似文献
10.
Anatoly Dubnovitsky Anders Sandberg M. Mahafuzur Rahman Iryna Benilova Christofer Lendel Torleif H?rd 《PloS one》2013,8(7)
Structural and biochemical studies of the aggregation of the amyloid-β peptide (Aβ) are important to understand the mechanisms of Alzheimer''s disease, but research is complicated by aggregate inhomogeneity and instability. We previously engineered a hairpin form of Aβ called Aβcc, which forms stable protofibrils that do not convert into amyloid fibrils. Here we provide a detailed characterization of Aβ42
cc protofibrils. Like wild type Aβ they appear as smooth rod-like particles with a diameter of 3.1 (±0.2) nm and typical lengths in the range 60 to 220 nm when observed by atomic force microscopy. Non-perturbing analytical ultracentrifugation and nanoparticle tracking analyses are consistent with such rod-like protofibrils. Aβ42
cc protofibrils bind the ANS dye indicating that they, like other toxic protein aggregates, expose hydrophobic surface. Assays with the OC/A11 pair of oligomer specific antibodies put Aβ42
cc protofibrils into the same class of species as fibrillar oligomers of wild type Aβ. Aβ42
cc protofibrils may be used to extract binding proteins in biological fluids and apolipoprotein E is readily detected as a binder in human serum. Finally, Aβ42
cc protofibrils act to attenuate spontaneous synaptic activity in mouse hippocampal neurons. The experiments indicate considerable structural and chemical similarities between protofibrils formed by Aβ42
cc and aggregates of wild type Aβ42. We suggest that Aβ42
cc protofibrils may be used in research and applications that require stable preparations of protofibrillar Aβ. 相似文献