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Paul N. Carding Sue Roulstone Kate Northstone ALSPAC Study Team 《Journal of voice》2006,20(4):623-630
There is only very limited information on the prevalence of voice disorders, particularly for the pediatric population. This study examined the prevalence of dysphonia in a large cohort of children (n = 7389) at 8 years of age. Data were collected within a large prospective epidemiological study and included a formal assessment by one of five research speech and language therapists as well as a parental report of their child's voice. Common risk factors that were also analyzed included sex, sibling numbers, asthma, regular conductive hearing loss, and frequent upper respiratory infection. The research clinicians identified a dysphonia prevalence of 6% compared with a parental report of 11%. Both measures suggested a significant risk of dysphonia for children with older siblings. Other measures were not in agreement between clinician and parental reports. The clinician judgments also suggested significant risk factors for sex (male) but not for any common respiratory or otolaryngological conditions that were analyzed. Parental report suggested significant risk factors with respect to asthma and tonsillectomy. These results are discussed in detail. 相似文献
303.
Aditya Narayan Singh 《应用光谱学评论》2016,51(5):359-378
Positron Annihilation Spectroscopy (PAS), sometimes refered to as Positron Annihilation Lifetime Spectroscopy (PALS), are non-destructive techniques commonly used for defects and voids study in materials. It provides a handy tool for in-depth profiling down to few microns, and in determining open volume defects like dislocation, agglomerates, and vacancies at ppm concentration. PAS with the aid of Doppler broadening has certainly opened a new gateway in the spectroscopy of solid state physics, metals, RO systems, and semiconductors. Since it is an antiparticle of the electron it gives better information on the electron density in the material of interest. The lifetime of a positron is a complex function of electron density present at the annihilation site. To add beauty, in principle PAS gives the type and concentration of the defect independently by a single measurement. This article presents PAS based on the most relevant, most iconic, and most recent references. 相似文献
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Heather M. Stein Surendra R. Gundam Aditya Bansal Nicholas R. Nelson Geoffry L. Curran Timothy R. DeGrado Mark A. Frye John D. Port Val J. Lowe Melissa E. Murray Dr. Mukesh K. Pandey 《European journal of organic chemistry》2023,26(3):e202201031
Glycogen synthase kinase-3 α/β is involved in dysregulation of neuronal tau protein in Alzheimer's disease (AD). There is an unmet clinical need for a blood-brain barrier (BBB) permeable positron emission tomography (PET) probe for imaging of GSK-3α/β in the brain to understand the pathogenesis of AD. Herein, we synthesized two PET probes, [18F]F-CNBI and [18F]F-CNPIFE, and evaluated their BBB permeability and affinity towards GSK-3α/β. [19F]F-CNPIFE showed higher in-vitro binding towards GSK-3α/β (IC50=19.4±2.5 nM; n=3, for GSK-3α, IC50=19.4±3.8 nM; n=3, for GSK-3β) compared to [19F]F-CNBI (IC50=107.6±26.0 nM; n=4, for GSK-3α, IC50=105.3±18.2 nM; n=3, for GSK-3β). [18F]F-CNPIFE showed 9.5-fold higher brain uptake than [18F]F-CNBI, in normal FVB/NJ mice, which was increased by additional 1.5-fold on co-administration of [19F]F-CNPIFE with respect to [18F]F-CNBI. Overall, [18F]F-CNPIFE is a promising PET probe for GSK-3α/β imaging and warrants further evaluation in an AD mouse model. 相似文献
305.
Crouzier T Nimmagadda A Nollert MU McFetridge PS 《Langmuir : the ACS journal of surfaces and colloids》2008,24(22):13173-13181
Single walled carbon nanotubes (SWNTs) continue to demonstrate the potential of nanoscaled materials in a wide range of applications. The ability to modulate the mechanical or electrical properties of a material by varying the SWNT component may result in diverse "application tunable" materials. Similarly, biomaterials used in tissue engineering applications may benefit from these characteristics by varying electrical and mechanical properties to enhance or direct tissue specific regeneration. The interactions between SWNTs and cellular systems need to be optimized to integrate these highly hydrophobic nanoparticles within an aqueous environment while maintaining their unique properties. We assessed solubility, conductance, and cellular interactions between four different SWNT preparations (unrefined, refined, and SWNT with either albumin or human plasma adsorbed). Initial interactions between cells and SWNTs were assessed within a 3D environment using a red blood cell lysis model, with longer-term interactions assessing the effects on PC12 and 3T3 fibroblast function when cultured on SWNT-collagen composite hydrogels. After SWNT purification, the lytic effect on red blood cells (RBCs) is significantly reduced from 11% to 0.7%, indicating manufacturing contaminants play a significant role in undesirable cell interactions. Nanotubes with either human plasma or albumin physisorbed onto the nanotube surface were significantly more hydrophilic than either unrefined or refined preparations and displayed improved RBC interactions. Despite improved dispersion, purification, and adsorption of either plasma or albumin, SWNTs caused a significant reduction in conductance. Although the molecular interactions occurring at the cell membrane remain unclear, these investigations have identified two main factors contributing to membrane failure: manufacturing impurities and to a lesser extend the material's innate hydrophobicity. Although purification is a critical step to remove toxic manufacturing contaminants, care must be taken to ensure improved aqueous dispersion does not compromise desirable mechanical and electrical attributes. 相似文献
306.
Maraschek M Gantenbein G Yu Q Zohm H Günter S Leuterer F Manini A;ECRH Group;ASDEX Upgrade Team 《Physical review letters》2007,98(2):025005
The efficiency of generating a helical current in magnetic islands for the purpose of suppression of neoclassical tearing modes (NTMs) by electron cyclotron current drive (ECCD) is studied experimentally in the ASDEX Upgrade tokamak. It is found that the efficiency of generating helical current by continuous current drive in a rotating island drops drastically as the width 2d of the co-ECCD driven current becomes larger than the island width W. However, by modulating the co-ECCD in phase with the rotating islands O point, the efficiency can be recovered. The results are in good agreement with theoretical calculations taking into account the equilibration of the externally driven current on the island flux surfaces. The result is especially important for large next-step fusion devices, such as ITER, where 2d>W is expected to be unavoidable during NTM suppression, suggesting that modulation capability should be foreseen. 相似文献
307.
HL-2M 装置 300MVA 脉冲发电机组的调速装置高压变频器主要由输入和输出部分、功率单元、控
制部分组成。对高压变频器进行了调试及试验运行。试验表明其输入谐波含量小,输出波形也是完美正弦波,启
动到工作转速的时间为 16min,再加速时间未超过 5min,能够满足实验放电要求。根据调试情况对空载电流及转
子时间常数进行了优化,在空载电流为 300A、转子时间常数为 1.34s 时,其性能为最优。 相似文献
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