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491.
应用碳离子束进行大分割放射治疗从而缩短治疗周期是碳离子束治疗的优势之一。为研究大分割放疗增加单次照射剂量后,碳离子束相对生物学效应(RBE)的变化,应用细胞存活线性平方(LQ)模型推导出RBE与剂量的依赖关系。基于此关系研究了具有不同辐射敏感性的肿瘤细胞和正常组织细胞RBE随剂量的变化。结果表明,在0~20 Gy范围内,不论肿瘤细胞与正常组织细胞具有怎样的辐射敏感性,肿瘤细胞的RBE值始终大于正常组织细胞。此外,基于理论推导和对相关实验数据的分析,证实了RBE随剂量增加而递增现象的存在。这些结果对应用碳离子束进行大分割放射治疗具有重要的指导作用。Short treatment course due to the suitability of hypofractionated regimen for carbon ion beam is one of the advantages of carbon ion radiotherapy. To study the dependence of relative biological effectiveness (RBE) on dose, the relationship between RBE and dose was deduced through the linear-quadratic (LQ) model. Based on the relationship, the change of RBE of tumor cells and normal tissue cells with different radiosensitivities with dose was studied. The results showed that the RBE value of tumor cells was always greater than that of normal tissue cells in the dose range of 0~20 Gy, regardless of the radiosensitivity of tumor and normal tissue cells. In addition, based on theoretical deduction and analysis of the relevant experimental data, the existence of RBE increase with increasing dose was verified. These results are of great significance for conducting hypofractionated radiotherapy with carbon ion beam. 相似文献
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A. Shahzad A. B. Phatangare V. D. Bharud M. S. Bhadane C. D. Tahakik B. J. Patil 《辐射效应与固体损伤》2017,172(11-12):931-951
A system for the electron and photon therapy has been designed and developed at SAMEER, IITB, Mumbai. All the components of the system such as the 270° beam bending electromagnet, trim coils, magnet chamber, electron scattering foil, slits, applicators, etc., were designed and fabricated indigenously. The electrons of 6, 8, 9, 12, 15 and 18?MeV energies were provided by a linear accelerator, indigenously designed and made at SAMEER, IITB campus, Mumbai. The electron beam from the LINAC enters the magnet chamber horizontally, and after deflection and focusing in the 270° bending magnet, comes out of the exit port, and travels a straight path vertically down. After passing through the beryllium and tantalum scattering foils, the electron beam gets scattered and turns into a solid cone shape such that the diameter increases with the travel distance. The simulation results indicate that at the exit port of the 270° beam bending magnet, the electron beam has a divergence angle of ≤ 3?mrad and diameter ~2–3?mm, and remains constant over 6–18?MeV. Normally, 6–18?MeV electrons are used for the electron therapy of skin and malignant cancer near the skin surface. On a plane at a distance of 100?cm from the scattering foils, the size of the electron beam could be varied from 10?cm?×?10?cm to 25?cm?×?25?cm using suitable applicators and slits. Different types of applicators were therefore designed and fabricated to provide required beam profile and dose of electrons to a patient. The 6?MeV cyclic electron accelerator called Race-Track Microtron of S. P. Pune University, Pune, was extensively used for studying the performances of the scattering foils, electron beam uniformity and radiation dose measurement. Different types of thermoluminescent dosimetry dosimeters were developed to measure dose in the range of 1–10kGy. 相似文献
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Direct measurement and analysis of total ionizing dose effect on 130 nm PD SOI SRAM cell static noise margin 下载免费PDF全文
In this work, the total ionizing dose(TID) effect on 130 nm partially depleted(PD) silicon-on-insulator(SOI) static random access memory(SRAM) cell stability is measured. The SRAM cell test structure allowing direct measurement of the static noise margin(SNM) is specifically designed and irradiated by gamma-ray. Both data sides' SNM of 130 nm PD SOI SRAM cell are decreased by TID, which is different from the conclusion obtained in old generation devices that one data side's SNM is decreased and the other data side's SNM is increased. Moreover, measurement of SNM under different supply voltages(Vdd) reveals that SNM is more sensitive to TID under lower Vdd. The impact of TID on SNM under data retention Vddshould be tested, because Vddof SRAM cell under data retention mode is lower than normal Vdd.The mechanism under the above results is analyzed by measurement of I–V characteristics of SRAM cell transistors. 相似文献
497.
Radiation processing of wastewater evaluated by toxicity assays 总被引:3,自引:0,他引:3
S. I. Borrely M. H. O. Sampa C. B. Pedroso H. Oikawa C. G. Silveira E. H. Cherbakian M. C. F. Santos 《Radiation Physics and Chemistry》2000,57(3-6):507-511
Biological assays have been applied to industrial effluents and sewage influents, from distinct sites, before and after being submitted to ionizing radiation treatment. The objective of this study was to evaluate the efficiency of radiation, mainly electron beam accelerator, for the acute toxicity removal. The selected sampling presented a very toxic level and the radiation process was efficient for toxicity removal for 87.7% of irradiated samples. The sewage influents required lower radiation doses to reduce toxicity when compared to raw industrial effluents. 相似文献
498.
红外光吸收研究35MeV/u Ar离子辐照半晶质聚酯膜引起的效应 总被引:3,自引:1,他引:2
35MeV/u Ar离子在室温下辐照了多层堆叠的半晶质聚酯膜,采用傅立叶转换的红外光吸收技术分析和研究了由辐照引起的化学键断裂及其对离子剂量、离子在样品中的平均电子能量损失和吸收剂量的依赖性.结果表明,辐照导致聚酯膜中发生了明显的化学键断裂,断键过程主要发生在反式构型的乙二醇残留物和苯环的对位上,苯环的基本结构在辐照中变化较小.断键不仅强烈地依赖于离子的照射剂量,而且还跟样品中电子能量沉积密切相关,明显的断键发生在4.0MGy以上的吸收剂量. 相似文献
499.
步进扫描投影光刻机剂量控制参量优化新算法研究 总被引:1,自引:0,他引:1
提出了一种以生产率、剂量精度与激光器使用成本三者最佳匹配为优化目标的步进扫描投影光刻机剂量控制参量优化新算法及其数学模型,通过将激光器重复频率作为可调参量并引入有效脉冲个数的概念,获得了有效剂量区间内任意给定剂量所应采取的优化策略并给出了剂量控制参量的具体计算方法。理论推导和模拟计算结果表明,新算法既保持了原算法在生产率和剂量精度优化方面的优势,又改进了原算法在激光器成本优化目标上的缺陷。随着准分子激光器及其剂量控制技术的进一步发展,新算法可望更能显示出其优越性并具有更广阔的应用前景。 相似文献
500.
O. I. Shpotyuk E. R. Skordeva R. Ya. Golovchak V. D. Pamukchieva A. P. Kovalskii 《Journal of Applied Spectroscopy》1999,66(5):749-753
The radiative-optical properties of chalcogenide glass-like semiconductors of the As2S2−Ge2S3 system in the region of a topological 2D-3D-phase transition are investigated. It is shown that γ-irradiation of samples
by an absorbed dose of 4.4 · 106 Gy leads to a longwave shift of their optical-transmission edge in the spectrum. The effect observed depends on the structural
type of the glasses investigated and changes considerably near the 2D-3D-phase transition. Two components of the transmission-edge
shift are detected: a static component, which remains unchanged for a long time after irradiation of the samples, and a dynamic
one, which gradually fades in 2–3 months. It is suggested that the microstructural mechanism of these changes is attributable
to processes of coordination defect formation in the structural skeleton of the samples.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, pp. 657–660, September–October, 1999. 相似文献