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991.
Computational design and screening of promising energetic materials: Novel azobis(tetrazoles) with ten catenated nitrogen atoms chain 下载免费PDF全文
Piao He Jian‐Guo Zhang Le Wu Jin‐Ting Wu Tong‐Lai Zhang 《Journal of Physical Organic Chemistry》2017,30(10)
Density functional theory methods were used to study on 2 N10 compounds, 1,1′‐azobis(tetrazole) and 1,1′‐azobis(5‐methyltetrazole). We systematically investigated 10 novel substituted azobis(tetrazoles) with 10 catenated nitrogen atoms and various energetic groups (–CF3 1 , –C(NO2)3 3 , –N3 5 , –NH2 6 , –NHNH2 7 , –NHNO2 8 , –NO2 9 , –OCH3 10 , –OH 11 , –ONO2 12 ). The optimized geometry, frontier molecular orbitals, electrostatic potential, Infrared and nuclear magnetic resonance spectrum were calculated for inspecting the molecular structure and stability as well as chemical reactivity. The effects of different substituents on the density, enthalpy of formation, heat of explosion, detonation velocity and pressure, and sensitivity of the azobis(tetrazole) derivatives have been investigated. Compound 9 with nitro was found to have remarkable detonation performances (D = 9.61 km/s, P = 42.14 GPa), which are close to the excellent explosive CL‐20. Results show that compounds 1 , 3 , 4 , 7 , 9 , 11, and 12 have high potential to replace RDX. It is surprising that compounds 1 , 3 , 9, and 12 possess better energetic properties than HMX. These novel substituted azobis(tetrazoles) with unique N10 structure may be promising candidates of HEDMs with outstanding performance and acceptable sensitivities. 相似文献
992.
993.
Optical tomography system based on modified simultaneous iterative reconstruction tech-nique is designed to real-time monitor spatial distribution and diffusion process of smoke plume in a power plant. Concentration profiles, rather than just a point value, of smoke plume concentrations are the goal of this method, and the tomography algorithm is ana-lyzed. According to incomplete projection data in the process of reconstruction and exiting noise interference, the modified simultaneous iterative reconstruction technique (SIRT) is adopted to extract the information of the trace gas concentration by a fan beam scanning and is compared to the conventional SIRT. Three evaluation indexes show that the recon-struction effect is the best by choosing proper relaxation factor, which reduces the index d to 0.044 from 0.435 and reduces the index r to 0.044 from 0.376 for 5500 iterations. Hence, the modified algorithm performs better in estimating the shape of the plume, this method is used to process the measured spectra in field campaign, the reconstruction results and the measured data are basically consistent, which is further confirmed by the experimental results. 相似文献
994.
X.L. Tong K. Lin D.J. Lv M.H. Yang Z.X. Liu D.S. Zhang 《Applied Surface Science》2009,255(18):7995-7998
(1 ? x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–PT) thin films have been deposited on quartz substrates using pulsed laser deposition (PLD). Crystalline microstructure of the deposited PMN–PT thin films has been investigated with X-ray diffraction (XRD). Optical transmission spectroscopy and Raman spectroscopy are used to characterize optical properties of the deposited PMN–PT thin films. The results show that the PMN–PT thin films of perovskite structure have been formed, and the crystalline and optical properties of the PMN–PT thin films can be improved as increasing the annealing temperature to 750 °C, but further increasing the annealing temperature to 950 °C may lead to a degradation of the crystallinity and the optical properties of the PMN–PT thin films. In addition, a weak second harmonic intensity (SHG) has been observed for the PMN–PT thin film formed at the optimum annealing temperature of 750 °C according to Maker fringe method. All these suggest that the annealing temperature has significant effect on the structural and optical properties of the PMN–PT thin films. 相似文献
995.
The aim of this study was to investigate the influences of time pressure on long-range correlations in heart rate variability (HRV), the effects of relaxation on the cardiovascular regulation system and the advantages of detrended fluctuation analysis (DFA) over the conventional power spectral analysis in discriminating states of the cardiovascular systems under different levels of time pressure. Volunteer subjects (n=10, male/female=5/5) participated in a computer-mouse task consisting of five sessions, i.e. baseline session (BSS) which was free of time pressure, followed by sessions with 80% (SS80), 100% (SS100), 90% (SS90) and 150% (SS150) of the baseline time. Electrocardiogram (ECG) and task performance were recorded throughout the experiments. Two rest sessions before and after the computer-mouse work, i.e. RS1 and RS2, were also recorded as comparison. HRV series were subsequently analyzed by both conventional power spectral analysis and detrended fluctuation analysis (DFA). The long-term scaling exponent α2 by DFA was significantly lower in SS80 than that in other sessions. It was also found that short-term release of time pressure had positive influences on the cardiovascular system, i.e. the α2 in RS2 was significantly higher than that in SS80, SS100 and SS90. No significant differences were found between any two sessions by conventional power spectral analysis. Our results showed that DFA performed better in discriminating the states of cardiovascular autonomic modulation under time pressure than the conventional power spectral analysis. 相似文献
996.
In [A.L. Carey, J. Phillips, A. Rennie, Twisted cyclic theory and an index theory for the gauge invariant KMS state on Cuntz algebras. arXiv:0801.4605], we presented a K-theoretic approach to finding invariants of algebras with no non-trivial traces. This paper presents a new example that is more typical of the generic situation. This is the case of an algebra that admits only non-faithful traces, namely SUq(2) and also KMS states. Our main results are index theorems (which calculate spectral flow), one using ordinary cyclic cohomology and the other using twisted cyclic cohomology, where the twisting comes from the generator of the modular group of the Haar state. In contrast to the Cuntz algebras studied in [A.L. Carey, J. Phillips, A. Rennie, Twisted cyclic theory and an index theory for the gauge invariant KMS state on Cuntz algebras. arXiv:0801.4605], the computations are considerably more complex and interesting, because there are non-trivial ‘eta’ contributions to this index. 相似文献
997.
Wai Tung Lee Xin Tong Dennis Rich Yun Liu Michael Fleenor Akbar Ismaili Joshua Pierce Mark Hagen Jonny Dadras J. Lee Robertson 《Physica B: Condensed Matter》2009,404(17):2670-2672
In recent years, polarized 3He gas has increasingly been used as neutron polarizers and polarization analyzers. Two of the leading methods to polarize the 3He gas are the spin-exchange optical pumping (SEOP) method and the meta-stable exchange optical pumping (MEOP) method. At present, the SEOP setup is comparatively compact due to the fact that it does not require the sophisticated compressor system used in the MEOP method. The temperature and the laser power available determine the speed, at which the SEOP method polarizes the 3He gas. For the quantity of gas typically used in neutron scattering work, this speed is independent of the quantity of the gas required, whereas the polarizing time using the MEOP method is proportional to the quantity of gas required. Currently, using the SEOP method to polarize several bar-liters of 3He to 70% polarization would require 20−40 h. This is an order of magnitude longer than the MEOP method for the same quantity of gas and polarization. It would therefore be advantageous to speed up the SEOP process. In this article, we analyze the requirements for temperature, laser power, and the type of alkali used in order to shorten the time required to polarize 3He gas using the SEOP method. 相似文献
998.
Ni25+离子1s23s-1s2np跃迁的全能域理论研究 总被引:2,自引:2,他引:0
用全实加关联方法计算了Ni25+离子1s23s和1s2np (n 9)态的能量.通过引入价电子的有效核电荷,在类氢近似下,估算了对能量的高阶相对论修正和QED修正.计算了该离子1s23s-1s2np的跃迁能,波长和在三种规范下的振子强度.依据量子亏损理论,确定了Rydberg系列1s2np的量子数亏损,据此可以实现对任意高激发态(n 10)的能量的可靠预言;得到该离子从1s23s态到电离阈附近高激发1s2np态间的跃迁振子强度以及到相应连续态跃迁的振子强度密度. 相似文献
999.
GJ 436b is a Neptune-size planet with 23.2 Earth masses in an elliptical orbit of period 2.64 days and eccentricity 0.16.
With a typical tidal dissipation factor (Q′∼106) as that of a giant planet with convective envelope, its orbital circularization timescale under internal tidal dissipation
is around 1 Ga, at least two times less than the stellar age (> 3 Ga). A plausible mechanism is that the eccentricity of GJ
436b is modulated by a planetary companion due to their mutual perturbation. Here we investigate this possibility from the
dynamical viewpoint. A general method is given to predict the possible locations of the dynamically coupled companions, including
nearby/distance non-resonant or mean motion resonance orbits with the first planet. Applying the method to GJ 436 system,
we find it is very unlikely that the eccentricity of GJ 436b is maintained at the present location by a nearby/distance companion
through secular perturbation or mean motion resonance. In fact, in all these simulated cases, GJ 436b will undergo eccentricity
damp and orbital decay, leaving the present location within the stellar age. However, these results do not rule out the possible
existence of planet companions in nearby/distance orbits, although they are not able to maintain the eccentricity of GJ 436b.
Supported by the National Natural Science Foundation of China (Grant Nos. 10833001 and 10778603) and the National Basic Research
Program of China (Grant No. 2007CB4800) 相似文献
1000.