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511.
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Attenuating performance of a polymer layer coated onto floating structures subjected to water blasts
Yong Chen Zhiyi Zhang Yu Wang Hongxing Hua Houyu Gou 《European Journal of Mechanics - A/Solids》2009,28(3):591-598
The water blast attenuating performance of a polymer layer coated onto floating structures has been experimentally investigated. A series of contrastive live fire tests were conducted on a rectangular metal box before and after coating a layer of polymer on its outer hull. The blast responses of the box and water pressure near the wet surface were monitored and analyzed. Test results show that the transmitted impulse at the initial FSI stage can be reduced by almost 50%, owing to the rubber wall flexibility. Consequently, both acceleration and strain peaks of the box induced by the first shock wave can be effectively reduced. Further shock response spectrum analysis indicates that the coating performs like a low pass filter with cutoff frequency at about 50 Hz. Response components higher than 50 Hz can be attenuated effectively, but for components lower than the cutoff frequency, the attenuating effect is limited. 相似文献
513.
Wei Huang Hui‐Fen Qian Yi‐Hu Chen Shao‐Hua Gou Yi‐Zhi Li 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(8):o479-o480
The title compound, (1S,3R)‐3‐carbamoyl‐2,2,3‐trimethylcyclopentane‐1‐carboxylic acid, C10H17NO3, was synthesized and characterized by IR, EA, ES–MS (electrospray ionization mass spectra), 1H NMR, 13C NMR and X‐ray diffraction techniques. The two independent molecules form a two‐dimensional network via O—H⃛O and N—H⃛O hydrogen‐bonding interactions between their carboxylic acid and carbamoyl groups. 相似文献
514.
Electronic Structure and Circular Dichroism of Natural Alboatisins Isolated from Aerial Parts of Isodon Albopilosus: DFT and TDDFT Study
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The stable conformations of a series of bioactive molecules, (?)-alboatisins A?C, are identified via Monte Carlo searching with the MMFF94 molecular mechanics force field. Then, the optical rotation (OR) values, vibrational circular dichroism (VCD), and electronic circular dichroism (ECD) spectra were calculated using the gradient-corrected density functional theory method. The vibrational and transition modes of molecular chirality were explored in terms of their microscopic origin. The calculated specific rotations are in agreement with the experimental values. From the OR analysis, it was concluded that optical rotation values areregulated by hydroxyl substitution. Vibrations occurring on the chiral skeleton may cause strong absorption in VCD spectra; VCD spectra are thus the spectral response to deformation vibrations on the chiral carbon skeleton. The lowest-energy negative Cotton effect is caused by σ→π* transition. Frontier molecular orbital analysis showed that strong ECD absorptions are produced when the dominant transition on the chiral skeleton is asymmetric; ECD spectra show the result of transitions lacking asymmetry on the chiral skeleton. 相似文献
515.
本文利用基于密度泛函理论的第一性原理研究了不同浓度的Mo掺杂BiVO4的V位的电子结构、光学性质和光催化性能.缺陷形成能的计算结果说明BiMoxV1-xO4(x=0.0625, 0.125, 0.25)三种掺杂体系都是可以稳定存在的.电子结构计算结果表明:BiMoxV1-xO4(x=0, 0.0625, 0.125, 0.25)四种体系的带隙分别为2.123 eV,2.142 eV,2.160 eV和2.213 eV.掺杂BiVO4体系的带隙值均大于本征BiVO4,且带隙随着Mo浓度的增加而增大. BiMoxV1-xO4(x=0.0625, 0.125, 0.25)三种掺杂体系的能带结构全部向低能量区域移动,导致掺杂体系导带底越过费米能级,Mo掺杂BiVO4后具... 相似文献
516.
As present NO donor drugs cannot localize to release NO at the hypoxic site, along with the short half-life and bidirectional regulation of NO, they are unable to overcome low bioavailability and side effects in the treatment of myocardial hypoxia injury. In this study, we designed and prepared a novel hypoxia-activated NO donor (Hano) by hybridization of a known NO donor compound (Nno) with a hypoxia-activated group. Hano and isosorbide dinitrate were compared in terms of NO release and anti-myocardial hypoxia injury. Furthermore, the effects of Hano and Nno on releasing NO, dilating blood vessels, and preventing myocardial hypoxia injury were studied and compared in smooth muscle cells, cardiomyocytes and mice. The results showed that the NO release by Hano increased either in smooth muscle cells or in myocardial cells under hypoxia conditions. Significantly, Hano was found capable of dilating blood vessels and attenuating hypoxia injury both in vitro and in vivo, and has great potential as a hypoxia-activated NO donor drug to treat hypoxic heart diseases.A novel HAP-type NO donor was found to release NO under hypoxia locally. It dilates blood vessels in smooth muscle cells and attenuates myocardial hypoxia injury in cardiomyocytes. 相似文献
517.
518.
针对200 L核废物桶分段γ扫描(SGS)过程中的效率刻度问题,提出了一种效率刻度函数模型,采用MCNP程序计算不同基质密度和γ射线能量条件下的离散断层效率,经过多元非线性回归获取函数参数,从而建立效率刻度函数,实现核废物桶SGS断层效率刻度。对核废物桶样品进行实验分析,结果表明:对于桶内基质分别为密度0.310 g·cm^-3的硅酸铝、密度0.595 g·cm^-3的木质纤维,桶内核素分别为活度3.110×10^5 Bq的点源137Cs、活度1.371×10^5 Bq的点源60Co,在桶内仅有单个点源存在的核素分布极端不均匀情况下,桶内核素活度重建误差在-37.68%~31.52%范围内。本文的方法能够准确有效实现核废物桶SGS断层效率矩阵计算,并确定核废物桶内放射性核素活度,满足实际检测要求。 相似文献
519.
本文测定了2-三氟甲基吡啶在2∽20 GHz频率范围内的高分辨转动光谱. 测定了转动常数、14N核四极耦合常数及离心畸变常数等一系列光谱参数. 同时还在自然丰度下测定了5个13C和1个14N单取代同位素异数体的光谱数据. 实验结果结合从头算准确地推导出2-三氟甲基吡啶的骨架结构. 实验测得同位素异数体的平面转动惯量Pcc数值均为44.46 u?2,表明此分子具有Cs对称性. 此外,本文计算了吡啶、2-氟吡啶、2-甲基吡啶和2-三氟甲基吡啶的分子表面静电势,以此分析了三氟甲基的取代对电子分布的影响. 相似文献
520.
四氨基铝酞菁作为过氧化物酶模拟酶新型红区荧光底物的研究 总被引:6,自引:0,他引:6
本文按照文献[1]合成了一种优良的红区荧光探针-四氨基铝酞菁(TAAIPc,在强酸性介质中,它的最大激发与最大发射波长分别在610nm和678nm处),并将它作为过氧化物酶模拟酶的红区荧光底物用于痕量过氧化氢的测定。由于在长波区具有荧光的天然物质很少,且溶液体系的散射光强度与1/λ^4成正比,因而在长波处进行样品测定时可以很好地避开背景荧光和散射光的干扰,检测限可得到较大的改善。 相似文献