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971.
根据量子统计模型 (QSM )的计算分析 ,找到了一个提取核反应过程中熵产生的新的可观测量 .核反应过程中约化d的产额d/ (d t 3 He 4 He)和熵有单调的函数关系 ,并且和体系的碎裂密度 (ρ/ ρ0 )及体系的N/Z都无关 ,可以作为提取核反应过程中熵产生的一个观测量 .和目前已经有的其他方法相比 ,约化d产额这一提取熵方法可以用于较低能量的重离子核反应中 ,并且数据处理分析简单 .对于 35MeV/u4 0 Ar 197Au的核反应过程所提取的熵和利用约化带电粒子多重性提取的熵结果一致 .结合后角类靶热核发射体系实验提取的同位素核温度为 4 7±1 2MeV及S/A =2 5± 0 5 ,根据熵和核温度的关联关系 ,可以确定其Breakup密度接近但小于 0 1(ρ/ ρ0 ) 相似文献
972.
等角基是正交基的推广,等角基具有和正交基相似的性质,因此研究等角基的性质能够为研究欧氏空间提供一种工具,加深对欧氏空间的了解.本文主要把n维欧氏空间中正交基的一些性质推广到等角基上,得到了五个关于等角基性质的定理. 相似文献
973.
We present a calculation of the electronic Raman cross section for the scattering of light across the energy gap of an antiferromagnetic insulator. The antiferromagnet is described in terms of a spin density wave state for the Hubbard model at half filling. We consider the coupling of the light to the current density and the inverse mass tensor on equal footing. A comparison of the cross section for different scattering geometries is given. 相似文献
974.
Xiaoyi Xie Yi Zhang Dong Li Yuxiu Fan Bin Huang Xiupei Yang 《Particle & Particle Systems Characterization》2023,40(10):2300039
Nanozymes can be used as favorable substitutes for natural enzymes because of their strong catalytic activity and good stability. At the same time, research on single-atom catalysts (SACs) with isolated metal atoms as active centers is also in full swing, showing excellent performance in a variety of catalytic reactions. With the in-depth study of SACs, people have a comprehensive understanding of them and put forward the concept of single-atom nanozymes (SAzymes) by combining nanozymes with SACs. As a new type of nanomaterial, SAzymes have attracted great interest due to their remarkable catalytic activity and rapid energy conversion. However, most applications of SAzymes are mainly in the fields of biomedicine and biosensing, and less research has been done in the field of the environment. Based on the amazing ability of nanozymes to detect and degrade pollutants, SAzymes are also used in the environmental field, and even they will show better capabilities. This review mainly analyses common transition metal-based SAzymes and describes their applications in the field of environmental pollutants. 相似文献
975.
We study the antiferromagnetic q-state Potts model on the square lattice for q=3 and q=4, using the Wang–Swendsen–Kotecký (WSK) Monte Carlo algorithm and a powerful finite-size-scaling extrapolation method. For q=3 we obtain good control up to correlation length 5000; the data are consistent with ()=Ae
2
p
(1+a
1
e
–
+ ...) as , with p1. The staggered susceptibility behaves as
stagg
5/3. For q=4 the model is disordered (2) even at zero temperature. In appendices we prove a correlation inequality for Potts antiferromagnets on a bipartite lattice, and we prove ergodicity of the WSK algorithm at zero temperature for Potts antiferromagnets on a bipartite lattice. 相似文献
976.
X. S. Wu F. Z. Wang J. S. Liu S. S. Jiang J. Gao 《Physica C: Superconductivity and its Applications》1999,320(3-4)
The nominal composition of Y0.8Ca0.2Ba2−xLaxCu3Oy (YBLCO) cuprates with x≤0.50 has been synthesized by the standard solid state reaction technique. X-ray diffraction and the resistivity measurements are used to characterize the structure and the superconductivity of YBLCO cuprates. There is no structural phase transition in the whole doping range. The dependencies of the lattice constants and some other structural parameters on the content of La for the samples YBLCO with x≤0.20 are different than those for the samples with x≥0.25. The zero resistance temperature Tc0 increases with the increase of the content of La in YBLCO as x≤0.20, and decreases as x≥0.25. We compared these results with those of Nd-doped Y0.8Ca0.2Ba2−zNdzCu3Oy cuprates. It seems that Tc0 is related to the structural parameters due to Ca and La codoping in YBLCO. 相似文献
977.
978.
The regime of atomization of Si in the presence of Fe-subgroup metals was investigated with the use of a “Saturn” spectrophotometer
and a “Graphit-2” electrothermic atomizer. The optimal operating parameters of the atomizer have been determined. It was established
that the optimal value of the ashing and the atomization temperatures are, respectively, 900–1000°C and 2400°C, the optimal
rate of temperature rise at the stage of atomization is 1400 K/sec, and the appropriate amount of Fe, Co and Ni additions
is 1–2 μg. It was established that the formation of gaseous silicides of the Fe-subgroup metals, the dissociation energies
of which are lower than the dissociation energies of Si oxides and carbides, increases the sensitivity for determination of
Si.
To whom correspondences should be addressed.
Institute of Single Crystals, National Academy of Sciences of Ukraine, 60, Lenin Ave., Khar'kov, 310001, Ukraine. Translated
from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 2, pp. 153–157, March–April, 1999. 相似文献
979.
MA YuQiang 《理论物理通讯》1999,31(4):537-542
We propose a soluble quantum spherical XY ferromagnet with a random field in the boson space. We obtain a general expression of the critical temperat ure Tc below which the ordered ferromagnet phase appears. The Imry-Ma result concerning the lower critical dimension dc = 4 is recovered, and the critical exponents near the critical temperature Tc are calculated. We show that the random-field fluctuations rather than the quantum fluctuations dominate the phase transition and critical behavior of the system. The entropy vanishes as Td/2 at low temperatures, contrary to the classical spherical model. 相似文献
980.
(Zn、Cd)S:Cu、Br黄色交流电致发光材料的晶体结构和发光特性 总被引:1,自引:0,他引:1
本文首次提出一种制备黄色交流粉末电致发光材料的新方法.在以ZnS为基质的绿色材料的基础上,低温扩散CdS,获得系列黄材料.并测量了晶体结构和发光特性. 相似文献