全文获取类型
收费全文 | 627篇 |
免费 | 21篇 |
国内免费 | 11篇 |
专业分类
化学 | 363篇 |
晶体学 | 4篇 |
力学 | 100篇 |
综合类 | 1篇 |
数学 | 39篇 |
物理学 | 152篇 |
出版年
2022年 | 10篇 |
2021年 | 11篇 |
2020年 | 12篇 |
2019年 | 9篇 |
2018年 | 6篇 |
2017年 | 12篇 |
2016年 | 13篇 |
2015年 | 13篇 |
2014年 | 16篇 |
2013年 | 21篇 |
2012年 | 24篇 |
2011年 | 37篇 |
2010年 | 20篇 |
2009年 | 19篇 |
2008年 | 32篇 |
2007年 | 26篇 |
2006年 | 28篇 |
2005年 | 33篇 |
2004年 | 29篇 |
2003年 | 14篇 |
2002年 | 19篇 |
2001年 | 16篇 |
2000年 | 31篇 |
1999年 | 26篇 |
1998年 | 18篇 |
1997年 | 15篇 |
1996年 | 13篇 |
1995年 | 6篇 |
1994年 | 10篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 12篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 2篇 |
1981年 | 10篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1973年 | 4篇 |
1964年 | 1篇 |
1959年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有659条查询结果,搜索用时 15 毫秒
101.
Hirano A Yoshikawa H Matsushita S Yamada Y Shiraki K 《Langmuir : the ACS journal of surfaces and colloids》2012,28(8):3887-3895
Nanoparticles taken into biological systems can have biological impacts through their interactions with cell membranes, accompanied by protein adsorption onto the nanoparticle surfaces, forming a so-called protein corona. Our current research aims to demonstrate that nanoscale protein aggregates behave like such nanoparticles with regard to the interaction with lipid membranes. In this study, the adsorption and disruption of the lipid membranes by protein aggregates were investigated using amyloid fibrils and nanoscale thermal aggregates of lysozyme. Both types of protein aggregates had disruptive effects on the negatively charged liposomes, similar to polycationic nanoparticles. Interestingly, adsorption of liposomes on the amyloid fibrils preceding disruption occurred even if the net charge of the liposome was zero, suggesting the importance of hydrophobic interactions in addition to electrostatic interactions. The results of the present study provide new insights into the biological impacts of nanoparticles in vivo. 相似文献
102.
This study focuses on the nonlinear dynamic and vibration characteristics of spur gear pair with local spalling defect to explore the spalling mechanism. The dynamic model of the gear pair with spalling defect and time-variant mesh stiffness is established to investigate the effect of spalling defect on mesh stiffness and dynamic response. The analytical solutions of the system which is deduced into four different stages of the gear with the time-variant stiffness in a mesh period are obtained. The dynamic responses with the evolvement of sapll are analyzed by using time history, phase contrail, Poincaré section and spectrum analysis. The spalling characteristics are also evaluated by employing statistical techniques, which shows that the spalling failure is suitable to be detected under low velocity and small excitation. The gearbox with spalling defect is designed and the experiments are carried out to get the dynamic characteristics of the spalling vibration signals. The results obtained herein show the good agreement qualitatively with the theoretical analysis, which provides a theoretical basis to spalling fault diagnosis of gearbox. 相似文献
103.
Wang X Guo Y Shi Y Belik AA Tsujimoto Y Yi W Sun Y Shirako Y Arai M Akaogi M Matsushita Y Yamaura K 《Inorganic chemistry》2012,51(12):6868-6875
The postspinel mineral MgAl(2)O(4) exists only under the severe pressure conditions in the subducted oceanic lithosphere in the Earth's deep interior. Here we report that its analogous oxide CdRh(2)O(4) exhibits a structural transition to a quenchable postspinel phase under a high pressure of 6 GPa at 1400 °C, which is within the general pressure range of a conventional single-stage multianvil system. In addition, the complex magnetic contributions to the lattice and metal nonstoichiometry that often complicate investigations of other analogues of MgAl(2)O(4) are absent in CdRh(2)O(4). X-ray crystallography revealed that this postspinel phase has an orthorhombic CaFe(2)O(4) structure, thus making it a practical analogue for investigations into the geophysical role of postspinel MgAl(2)O(4). Replacement of Mg(2+) with Cd(2+) appears to be effective in lowering the pressure required for transition, as was suggested for CdGeO(3). In addition, Rh(3+) could also contribute to this reduction, as many analogous Rh oxides of aluminous and silicic minerals have been quenched from lower-pressure conditions. 相似文献
104.
Sides CR Liyanage R Lay JO Philominathan ST Matsushita O Sakon J 《Journal of the American Society for Mass Spectrometry》2012,23(3):505-519
Pairing limited proteolysis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS)
to probe clostridial collagenase collagen binding domain (CBD) reveals the solution dynamics and stability of the protein,
as these factors are crucial to CBD effectiveness as a drug-delivery vehicle. MS analysis of proteolytic digests indicates
initial cleavage sites, thereby specifying the less stable and highly accessible regions of CBD. Modulation of protein structure
and stability upon metal binding is shown through MS analysis of calcium-bound and cobalt-bound CBD proteolytic digests. Previously
determined X-ray crystal structures illustrate that calcium binding induces secondary structure transformation in the highly
mobile N-terminal arm and increases protein stability. MS-based detection of exposed residues confirms protein flexibility,
accentuates N-terminal dynamics, and demonstrates increased global protein stability exported by calcium binding. Additionally,
apo- and calcium-bound CBD proteolysis sites correlate well with crystallographic B-factors, accessibility, and enzyme specificity.
MS-observed cleavage sites with no clear correlations are explained either by crystal contacts of the X-ray crystal structures
or by observed differences between Molecules A and B in the X-ray crystal structures. The study newly reveals the absence
of the βA strand and thus the very dynamic N-terminal linker, as corroborated by the solution X-ray scattering results. Cobalt
binding has a regional effect on the solution phase stability of CBD, as limited proteolysis data implies the capture of an
intermediate-CBD solution structure when cobalt is bound. 相似文献
105.
BiPd(2)O(4) and PbPd(2)O(4) were synthesized at high pressure of 6 GPa and 1500 K. Crystal structures of BiPd(2)O(4) and PbPd(2)O(4) were studied with synchrotron X-ray powder diffraction. BiPd(2)O(4) is isostructural with PbPt(2)O(4) and crystallizes in a triclinic system (space group P1, a = 5.73632(4) ?, b = 6.02532(5) ?, c = 6.41100(5) ?, α = 114.371(1)°, β = 95.910(1)°, and γ = 111.540(1)° at 293 K). PbPd(2)O(4) is isostructural with LaPd(2)O(4) and BaAu(2)O(4) and crystallizes in a tetragonal system (space group I4(1)/a, a = 5.76232(1) ?, and c = 9.98347(2) ? at 293 K). BiPd(2)O(4) shows ordering of Pd(2+) and Pd(4+) ions, and it is the third example of compounds with ordered arrangements of Pd(2+) and Pd(4+) in addition to Ba(2)Hg(3)Pd(7)O(14) and KPd(2)O(3). In PbPd(2)O(4), the following charge distribution is realized Pb(4+)Pd(2+)(2)O(4). PbPd(2)O(4) shows a structural phase transition from I4(1)/a to I2/a at about 240 K keeping basically the same structural arrangements (space group I2/a, a = 5.77326(1) ?, b = 9.95633(2) ?, c = 5.73264(1) ?, β = 90.2185(2)° at 112 K). BiPd(2)O(4) is nonmagnetic while PbPd(2)O(4) exhibits a significant temperature-dependent paramagnetic moment of 0.46μ(B)/f.u. between 2 and 350 K. PbPd(2)O(4) shows metallic conductivity, and BiPd(2)O(4) is a semiconductor between 2 and 400 K. 相似文献
106.
107.
In recent studies of generative adversarial networks (GAN), researchers have attempted to combine adversarial perturbation with data hiding in order to protect the privacy and authenticity of the host image simultaneously. However, most of the studied approaches can only achieve adversarial perturbation through a visible watermark; the quality of the host image is low, and the concealment of data hiding cannot be achieved. In this work, we propose a true data hiding method with adversarial effect for generating high-quality covers. Based on GAN, the data hiding area is selected precisely by limiting the modification strength in order to preserve the fidelity of the image. We devise a genetic algorithm that can explore decision boundaries in an artificially constrained search space to improve the attack effect as well as construct aggressive covert adversarial samples by detecting “sensitive pixels” in ordinary samples to place discontinuous perturbations. The results reveal that the stego-image has good visual quality and attack effect. To the best of our knowledge, this is the first attempt to use covert data hiding to generate adversarial samples based on GAN. 相似文献
108.
109.
Gan Chenquan Feng Qingdong Zhu Qingyi Zhang Zufan Zhang Yushu Xiang Yong 《Nonlinear dynamics》2020,100(2):1725-1740
Nonlinear Dynamics - This paper mainly aims to explore the propagation behaviors of computer virus over complex networks under the combined effects of network topology and removable storage media.... 相似文献
110.
Nonlinear Dynamics - Visually meaningful image encryption may keep the data security and appearance security of the digital images. However, there are still security and efficiency shortcomings... 相似文献