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61.
Aycan Akın Elçin Ekdal Yasemin Tuncer Arslanlar Mehmet Ayvacıklı Turgay Karalı Nurdoğan Can 《Luminescence》2015,30(6):830-834
Thermally stimulated luminescence glow curves of CaB4O7:Dy samples after β‐irradiation showed glow peaks at ~335, 530 and 675 K, with a heating rate of 2 K/s. The main peak at 530 K was analyzed using the Tmax–Tstop method and was found to be composed of at least five overlapping glow peaks. A curve‐fitting program was used to perform computerized glow curve deconvolution (CGCD) analysis of the complex peak of the dosimetric material of interest. The kinetic parameters, namely activation energy (E) and frequency factor (s), associated with the main glow peak of CaB4O7:Dy at 520 K were evaluated using peak shape (PS) and isothermal luminescence decay (ILD) methods. In addition, the kinetics was determined to be first order (b =1) by applying the additive dose method. The activation energies and frequency factors obtained using PS and ILD methods are calculated to be 0.72 and 0.72 eV and 8.76 × 105 and 1.44 × 106/s, respectively. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
62.
Although transient receptor potential (TRP) channel biology research has expanded rapidly in recent years, the field is hampered by the widely held, but relatively poorly investigated, belief that most of the pharmacological tools used to investigate TRP channel function may not be particularly selective for their intended targets. The objective of this study was therefore to determine if this was indeed the case by systematically evaluating the effects of three routinely used putative TRP channel antagonists, SKF 96365, flufenamic acid (FF) and 2-aminoethoxydiphenyl borate (2-APB) against one of the most widely expressed CNS receptor subtypes CNS, the human α1β2γ2 GABA(A) receptor. Using whole cell patch-clamp recording to record responses to rapidly applied GABA in the absence and presence of the three putative antagonists in turn we found that SKF 96365 (1-100 μM) and FF (1-100 μM) significantly inhibited GABA responses of recombinant human α1β2γ2 GABA(A) receptor stably expressed in HEK293 cells with IC(50) values of 13.4 ± 5.1 and 1.9 ± 1.4 μM, respectively, suppressing the maximal response to GABA at all concentrations used in a manner consistent with a non-competitive mode of action. SKF 96365 and FF also both significantly reduced desensitisation and prolonged the deactivation kinetics of the receptors to GABA (1mM; P<0.05). 2-APB (10-1000 μM) also inhibited responses to GABA at all concentrations used with an IC(50) value of 16.7 ± 5.4 μM (n=3-5) but had no significant effect on the activation, desensitisation or deactivation kinetics of the GABA responses. Taken together this investigation revealed that these widely utilised TRP channel antagonists display significant 'off-target' effects at concentrations that are routinely used for the study of TRP channel function in numerous biological systems and as such, data which is obtained utilising these compounds should be interpreted with caution. 相似文献
63.
Akihiro Nezu Akihiko TanimuraTakao Morita Akiko ShitaraYosuke Tojyo 《Biochimica et Biophysica Acta (BBA)/General Subjects》2006
LIBRA is a fluorescent biosensor of inositol 1,4,5-trisphosphate (IP3) and is composed of the ligand-binding domain of the rat type 3 IP3 receptor and cyan and yellow fluorescent proteins. We examined the responses of LIBRA and its IP3-insensitive mutant LIBRA-N to compounds known to inhibit IP3-induced Ca2+ release. Heparin, a competitive antagonist of IP3 receptors, increased the emission ratio of LIBRA but not that of LIBRA-N. In contrast, 2-aminoethoxydiphenyl borate, a known non-competitive inhibitor of IP3 receptor, decreased the emission ratios of both LIBRA and LIBRA-N. Thus, the concurrent use of LIBRA-N with LIBRA identifies nonspecific responses. These results indicate that LIBRA and its mutant control can be used to detect specific agonists and antagonists of IP3 receptors. We also demonstrate the utility of LIBRA and LIBRA-N in discriminating between specific and nonspecific responses in intact cells. 相似文献
64.
Lourdes Cabrera 《Inorganica chimica acta》2006,359(9):3066-3071
Trityl borate salts [4-RPyCPh3][B(C6F5)4] (R = H 1, tBu 2, Et 3, NMe24) and [R3PCPh3][B(C6F5)4] (R = Me 5, nBu 6, Ph[1] 7, p-MeC6H48) are readily prepared via equimolar reaction of the appropriate pyridine or phosphine and trityl borate [CPh3][B(C6F5)4]. The analogous reactions of PiPr3 affords the product [(p-iPr3P-C6H4)Ph2CH][B(C6F5)4] (9) while the corresponding reactions of Cy3P and tBu3P gave the cyclohexadienyl derivatives [(p-R3PC6H5)CPh2][B(C6F5)4] (R = Cy 10, tBu 11). X-ray structures of 5 and 9 are reported. 相似文献
65.
Hai-Yan Zhao Yong-Heng Xing Zhang-Peng Li Mao-Fa Ge Shu-Yun Niu 《Inorganica chimica acta》2009,362(11):4110-4118
A series of oxo-vanadium(IV) complexes: Tp∗VO(pzH∗)(CH3COO) (1), Tp∗VO(pzH∗)(CCl3COO) (2), Tp∗VO(pzH∗)(C6H5COO) (3), Tp∗VO(pzH∗)(m-NO2-C6H4COO)·CH3CN (4) and [Tp∗VO(pzH∗)(H2O)]+[m-NO2-C6H4-SO3]−·CH3OH (5) (Tp∗ = hydrotris(3,5-dimethylpyrazolyl)borate; pzH∗ = 3,5-dimethylpyrazole) are synthesized in methanol solution under physiological conditions. They are characterized by elemental analysis, IR, UV-Vis and X-ray crystallography. Structural analyses show that the vanadium atoms in complexes 1-5 are all in a distorted-octahedral environment with the N4O2 donor set, and intra- or inter-hydrogen bonding linkages have been also observed in each complex. Bromination reaction activity of the complexes has been evaluated by the method with phenol red as organic substrate in the presence of H2O2, Br− and phosphate buffer, indicating that they can be considered as potential functional model vanadium-dependent haloperoxidases. In addition, thermal analysis and quantum chemistry calculations were also performed and discussed in detail. 相似文献
66.
Aneta Czy? Jan Fronk Krzysztof Zab?ocki 《Biochemical and biophysical research communications》2009,381(2):176-2564
Tunicamycin effect on thapsigargin-induced store-operated calcium entry was investigated. Ca2+ influx was stimulated by 50% upon exposure of Jurkat cells to tunicamycin. Moreover, tunicamycin efficiently prevented the inhibition of store-operated calcium entry caused by dissipation of mitochondrial membrane potential. Protective action of tunicamycin on store-operated Ca2+ entry was also partially preserved in Jurkat cells depleted of ATP, while Ca2+ entry into ATP-deprived cells grown in tunicamycin-free medium was almost completely inhibited. Tunicamycin-evoked changes in cellular Ca2+ fluxes coincided with decreased glycosylation of STIM1 protein. Although the latter observation is correlative and needs additional confirmation it may suggest that deglycosylation of STIM1 protein deprives store-operated calcium entry system of an important regulatory mechanism. This study suggests a novel mechanism of modulation of the activity of store-operated calcium channels in lymphoidal cells. 相似文献
67.
Anastasija?ZaikoEmail author Darius?Daunys Sergej?Olenin 《Helgoland Marine Research》2009,63(1):85-94
Habitat engineering role of the invasive zebra mussel Dreissena polymorpha (Pallas) was studied in the Curonian lagoon, a shallow water body in the SE Baltic. Impacts of live zebra mussel clumps and
its shell deposits on benthic biodiversity were differentiated and referred to unmodified (bare) sediments. Zebra mussel bed
was distinguished from other habitat types by higher benthic invertebrate biomass, abundance, and species richness. The impact
of live mussels on biodiversity was more pronounced than the effect of shell deposits. The structure of macrofaunal community
in the habitats with >103 g/m2 of shell deposits devoid of live mussels was similar to that found within the zebra mussel bed. There was a continuous shift
in species composition and abundance along the gradient ‘bare sediments—shell deposits—zebra mussel bed’. The engineering
impact of zebra mussel on the benthic community became apparent both in individual patches and landscape-level analyses. 相似文献
68.
Calcium-dependent facilitation and graded deactivation of store-operated calcium entry in fetal skeletal muscle 总被引:2,自引:0,他引:2
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Activation of store-operated Ca2+ entry (SOCE) into the cytoplasm requires retrograde signaling from the intracellular Ca2+ release machinery, a process that involves an intimate interaction between protein components on the intracellular and cell surface membranes. The cellular machinery that governs the Ca2+ movement in muscle cells is developmentally regulated, reflecting maturation of the junctional membrane structure as well as coordinated expression of related Ca2+ signaling molecules. Here we demonstrate the existence of SOCE in freshly isolated skeletal muscle cells obtained from embryonic days 15 and 16 of the mouse embryo, a critical stage of muscle development. SOCE in the fetal muscle deactivates incrementally with the uptake of Ca2+ into the sarcoplasmic reticulum (SR). A novel Ca2+-dependent facilitation of SOCE is observed in cells transiently exposed to high cytosolic Ca2+. Our data suggest that cytosolic Ca2+ can facilitate SOCE whereas SR luminal Ca2+ can deactivate SOCE in the fetal skeletal muscle. This cooperative mechanism of SOCE regulation by Ca2+ ions not only enables tight control of SOCE by the SR membrane, but also provides an efficient mechanism of extracellular Ca2+ entry in response to physiological demand. Such Ca2+ signaling mechanism would likely contribute to contraction and development of the fetal skeletal muscle. 相似文献
69.
Sayli BS 《Biological trace element research》2003,93(1-3):19-29
In order to rule out the possibility of omitting some individuals in the study at field visits described in previous articles,
either because of the reluctance of the subject or because of his appointment elsewhere, fertility and infertility states
of borate workers of the Borax and Acid Plants in Bandirma, Balikesir are given. Balikesir is one of the four provinces with
large borate deposits of Turkey, and Bandirma is 1 of its 19 districts. This county is relatively far away from borate deposits,
and drinking water piped out through the springs has a boron amount between 0.10 and 0.82 ppm B. That the participants are
occupationally exposed to the mineral in essence is therefore conceivable. At the first phase of the investigation, 191 workers
were interviewed, as detailed previously. Among these, there were six infertiles of the primary type with a rate 3.1%. Boron-unrelated
infertile couples among sibs were found to be 2.6–3.6%, and 3.2% for three-generation marriages—none being higher than those
revealed in different sets of controls. In the second stage of work, computerized files of all workers of the facility and
all employees of the general management sharing the same location were checked without an interview. Twenty-four subjects
(3.4%) out of 712 workers were childless versus 2.7% among 108 employees, and 2.2% among 91 workers of a distantly located
sulfuric acid plant of the same complex. The differences were not significant, and these recent findings support the conclusion
already reached almost unambiguously that boron exposure at the present levels does not interfere with human reproduction. 相似文献
70.
Understanding the physical basis of protein aggregation covers strong physical and biomedical interests. Sickle hemoglobin (HbS) is a point-mutant form of normal human adult hemoglobin (HbA). It is responsible for the first identified "molecular disease," as its propensity to aggregation is responsible for sickle cell disease. At moderately higher than physiological pH value, this propensity is inhibited: The rate of aggregate nucleation becomes exceedingly small and solubility after polymerization increases. These order-of-magnitude effects on polymer nucleation rates and concurrent relatively modest changes of solubility after polymerization are here shown to be related to both pH-induced changes of location and shape of the liquid-liquid demixing (LLD) region. This allows establishment of a self-consistent contact between the thermodynamics of the solution as such (i.e., the LLD region), the kinetics of fiber nucleation, the theory of percolation, and the thermodynamics of gelation. The observed pH-induced changes are largely attributable to strong perturbations of hydrophobic hydration configurations and related free energy by electric charges. Similar mechanisms of effective control of aggregate nucleation rates by means of agents such as cosolutes, pH, salts, and additives, shifting the LLD and associated regions of anomalous fluctuations, promise to be relevant to the whole field of protein aggregation pathologies. 相似文献