全文获取类型
收费全文 | 174篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 61篇 |
力学 | 2篇 |
数学 | 25篇 |
物理学 | 89篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 1篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 6篇 |
2013年 | 5篇 |
2012年 | 13篇 |
2011年 | 17篇 |
2010年 | 6篇 |
2009年 | 9篇 |
2008年 | 14篇 |
2007年 | 13篇 |
2006年 | 3篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 10篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 4篇 |
排序方式: 共有177条查询结果,搜索用时 15 毫秒
31.
Sakari Leino Patrick JC May Paavo Alku Lassi A Liikkanen Hannu Tiitinen 《BMC neuroscience》2007,8(1):78
Background
In the field of auditory neuroscience, much research has focused on the neural processes underlying human sound localization. A recent magnetoencephalography (MEG) study investigated localization-related brain activity by measuring the N1m event-related response originating in the auditory cortex. It was found that the dynamic range of the right-hemispheric N1m response, defined as the mean difference in response magnitude between contralateral and ipsilateral stimulation, reflects cortical activity related to the discrimination of horizontal sound direction. Interestingly, the results also suggested that the presence of realistic spectral information within horizontally located spatial sounds resulted in a larger right-hemispheric N1m dynamic range. Spectral cues being predominant at high frequencies, the present study further investigated the issue by removing frequencies from the spatial stimuli with low-pass filtering. This resulted in a stepwise elimination of direction-specific spectral information. Interaural time and level differences were kept constant. The original, unfiltered stimuli were broadband noise signals presented from five frontal horizontal directions and binaurally recorded for eight human subjects with miniature microphones placed in each subject's ear canals. Stimuli were presented to the subjects during MEG registration and in a behavioral listening experiment. 相似文献32.
33.
L. P. Cavalcanti H. Haas H. N. Bordallo O. Konovalov T. Gutberlet G. Fragneto 《The European physical journal. Special topics》2007,141(1):217-221
Liposome suspensions comprising the synthetic cationic
lipid DOTAP, the zwitterionic DPPC and the anti-cancer agent
Paclitaxel were deposited on solid substrates and investigated by
X-ray and neutron reflectivity measurements at ESRF and ILL. Well
ordered multilamellar drug/lipid membranes were obtained,
such as indicated by the several orders of Bragg reflections in the
diffraction pattern. With an excess of Paclitaxel, additional
Bragg peaks from the drug crystalline phase could be observed.
Changes of the molecular organization in the drug-lipid system were
investigated as a function of relative humidity using a custom-built
controlled humidity chamber. For DOTAP multilayers the effects of
bilayer swelling were much more pronounced than for DPPC under
similar conditions, while the crystalline peaks of the drug were not
affected. The pronounced swelling of DOTAP multilayers might be
related to the electrostatic repulsion between the charged lipid
headgroups. 相似文献
34.
35.
Kowarik S Gerlach A Sellner S Schreiber F Cavalcanti L Konovalov O 《Physical review letters》2006,96(12):125504
We study kinetically controlled orientational and structural transitions of molecular thin films during growth in situ and in real time, using diindenoperylene (DIP) as an example. By time-resolved surface-sensitive x-ray scattering (out of plane and in plane), we follow the organic molecular beam deposition of DIP on silicon oxide, on stepped sapphire, and on rubrene as an organic model surface. We identify transitions for the few-monolayer (ML) regime, as well as for thick (several 10's of ML) films. We show that the differences in the interaction of DIP with the substrate change the thickness as well as temperature range of the transitions, which include (transient) strain, subtle changes of the orientation, as well as complete reorientation. These effects should be considered rather general features of the growth of organics, which, with its orientational degrees of freedom, is qualitatively different from growth of inorganics. 相似文献
36.
We introduce a method to resolve a symplectic orbifold(M,ω) into a smooth symplectic manifold . Then we study how the formality and the Lefschetz property of are compared with that of (M,ω). We also study the formality of the symplectic blow-up of (M,ω) along symplectic submanifolds disjoint from the orbifold singularities. This allows us to construct the first example of a simply connected compact symplectic manifold of dimension 8 which satisfies the Lefschetz property but is not formal, therefore giving a counter-example to a conjecture of Babenko and Taimanov. 相似文献
37.
DC Muddiman AP Null JC Hannis 《Rapid communications in mass spectrometry : RCM》1999,13(12):1201-1204
Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) has been used to determine the mass of a double-stranded 500 base-pair (bp) polymerase chain reaction (PCR) product with an average theoretical mass of the blunt-ended (i.e. unadenylated) species of 308 859.35 Da. The PCR product was generated from the linearized bacteriophage Lambda genome which is a double-stranded template. Utilization of ethanol precipitation in tandem with a rapid microdialysis step to purify and desalt the PCR product was crucial to obtain a precise mass measurement. The PCR product (0.8 pmol/μL) was electrosprayed from a solution containing 75% acetonitrile, 25 mM piperidine, and 25 mM imidazole and was infused at a rate of 200 nL/min. The average molecular mass and the corresponding precision were determined using the charge-states ranging from 172 to 235 net negative charges. The experimental mass and corresponding precision (reported as the 95% confidence interval of the mean) was 309 406 +/- 27 Da (87 ppm). The mass accuracy was compromised due to the fact that the PCR generates multiple products when using Taq polymerase due to the non-template directed 3'-adenylation. This results in a mixture of three PCR products with nearly identical mass (i.e. blunt-ended, mono-adenylated and di-adenylated) with unknown relative abundances that were not resolved in the spectrum. Thus, the experimental mass will be a weighted average of the three species which, under our experimental conditions, reflects a nearly equal concentration of the mono- and di-adenylated species. This report demonstrates that precise mass measurements of PCR products up to 309 kDa (500 bp) can be routinely obtained by ESI-FTICR requiring low femtomole amounts. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
38.
Josepha Yohanna de Jesus Eliane Santos de Carvalho Dantas Mairim Russo Serafini Paula dos Passos Menezes Juliana Cordeiro Cardoso Ricardo Luiz Cavalcanti Albuquerque-Jr Jivaldo do Rosário Matos Juliana Ferreira de Oliveira Irwin Rose Alencar de Menezes Francilene Amaral da Silva Adriano Antunes de Souza Araújo 《Journal of Thermal Analysis and Calorimetry》2016,123(3):2003-2012
39.
L.C. Alves M.G.S. Cavalcanti H.R.C. Araújo G.M. Silva D.L. Veras M.H.S. Paiva F.A. Brayner 《Micron (Oxford, England : 1993)》2009,40(5-6):659-664
Single dose of diethylcarbamazine (DEC) used in control programs is effective in breaking the transmission of filariasis. In order to investigate the effect of aggressive therapy on Wuchereria bancrofti (Wb) microfilariae, DEC was given to 29 patients who were positive for the circulating filarial antigen (CFA) assay but did not have clinical manifestations of filariasis, at 6 mg/kg/day for 12 days and again six months later using the same dosing regimen. For each patient, microfilarial density and serum CFA were followed up for two years. Ultrastructural analyses on Wb microfilariae obtained after repeated treatment with DEC were also performed. Microfilaremia and antigenemia decreased significantly after 12 months but returned to the initial levels after 24 months. This could indicate, as shown by other authors, that aggressive repeated therapy with DEC alone is ineffective in eradicating adult W. bancrofti, particularly in infected but asymptomatic individuals. The objective of the present study was to analyze the microfilaremic and antigenemic behavior and ultrastructural changes caused by different DEC concentrations in vitro in Wb microfilariae obtained from individuals who were sensitive and refractory to treatment. After in vitro treatment of the microfilariae using 5 and 10 μg/ml of DEC for 1 h, ultrastructural analysis revealed low levels of cell damage compared with embryos obtained from individuals from a different area who had never received DEC treatment before. The results obtained suggest that microfilariae from patients who receive repeated aggressive therapy are less sensitive to DEC in vitro. 相似文献
40.
Brustein VP Cavalcanti CL de Melo-Junior MR Correia MT Beltrão EI Carvalho LB 《Applied biochemistry and biotechnology》2012,166(2):268-275
Nowadays, there is an increase of investigations into the fibroadenoma, mainly because some studies have shown that the occurrence
of fibroadenoma is linked to an increased risk of developing breast carcinoma. Currently, the chemiluminescence biomarkers
are applied for validation methods and screening. Here, a lectin chemiluminescence is proposed as new histochemistry method
to identify carbohydrates in mammary tumoral tissues. The lectins concanavalin A (Con A) and peanut agglutinin (PNA) conjugated
to acridinium ester were used to characterize the glycocode of breast tissues: normal, fibroadenoma, and invasive duct carcinoma
(IDC). The lectin chemiluminescence expressed in relative light units (RLU) was higher in fibroadenoma and IDC than in normal
tissue for both lectins tested. The relationship RLU emission versus tissue area described a linear and hyperbolic curve for
IDC and fibroadenoma, respectively, using Con A whereas hyperbolic curves for both transformed tissues using PNA. RLU was
abolished by inhibiting the interaction between tissues and lectins using their specific carbohydrates: methyl-α-d-mannoside (Con A) and galactose (PNA). The intrinsic fluorescence emission did not change with combination of the lectins
(Con A/PNA) to the acridinium ester for hydrophobic residues. These results represent the lectin chemiluminescence as an alternative
of histochemistry method for tumoral diagnosis in the breast. 相似文献