全文获取类型
收费全文 | 268篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
化学 | 145篇 |
力学 | 2篇 |
数学 | 16篇 |
物理学 | 111篇 |
出版年
2022年 | 2篇 |
2017年 | 2篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 11篇 |
2012年 | 10篇 |
2011年 | 13篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 9篇 |
2007年 | 12篇 |
2006年 | 13篇 |
2005年 | 17篇 |
2004年 | 8篇 |
2003年 | 14篇 |
2002年 | 10篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1968年 | 2篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1943年 | 3篇 |
1942年 | 2篇 |
1924年 | 2篇 |
1905年 | 1篇 |
排序方式: 共有274条查询结果,搜索用时 15 毫秒
1.
Edward S. Fry 《量子光学学报》2006,12(B08):66-67
Since the data show that Bell inequalities are violated experimentally, we must conclude that any hidden variable theory (which correctly predicts experimental data ) will be non-local. But, to conclude that the experimental violations of Bell inequalities show quantum mechanics to be non-local is unjustified. Specifically, the key assumptions required to obtain a Bell inequality are ( 1 ) locality and (2) the assignment of meaningful ( non- negative) probabilities to seemingly physical correlations (Bell expresses these correlations via " hidden variables" ). Since the Bell inequality is violated by experiment, at least one of these assumptions is wrong. The widespread conclusion that locality must be relinquished is valid only if we retain the previously mentioned correlations ( "hidden variables" ). We will demonstrate that the latter are not physical observables - they are not elements of physical reality. 相似文献
2.
Shaw NM Blanis D Bodek A Budd H Coombes R Eno S Fry CA Harada H Ho YH Kim YK Kumita T Mori T Olsen SL Sill A Thorndike EH Ueno K Zheng HW Imlay R Kirk P Lim J McNeil RR Metcalf W Myung SS Cheng CP Gu P Li J Li YK Mao ZP Xu YT Zhu YC Abashian A Gotow K Hu K Low EH Mattson ME Naito F Piilonen L Sterner KL Lusin S Rosenfeld C Wang AT Wilson S Frautschi M Kagan H Kass R Trahern CG Breedon RE Kim GN Ko W Lander RL Maeshima K Malchow RL Smith JR Sparks K Williams MC Abe K Fujii Y Higashi Y Kim SK 《Physical review letters》1989,63(13):1342-1345
3.
Fry BG Wüster W Ryan Ramjan SF Jackson T Martelli P Kini RM 《Rapid communications in mass spectrometry : RCM》2003,17(18):2047-2062
The evolution of the venomous function of snakes and the diversification of the toxins has been of tremendous research interest and considerable debate. It has become recently evident that the evolution of the toxins in the advanced snakes (Colubroidea) predated the evolution of the advanced, front-fanged delivery mechanisms. Historically, the venoms of snakes lacking front-fanged venom-delivery systems (conventionally grouped into the paraphyletic family Colubridae) have been largely neglected. In this study we used liquid chromatography with mass spectrometry (LC/MS) to analyze a large number of venoms from a wide array of species representing the major advanced snake clades Atractaspididae, Colubrinae, Elapidae, Homalopsinae, Natricinae, Psammophiinae, Pseudoxyrhophiinae, Xenodontinae, and Viperidae. We also present the first sequences of toxins from Azemiops feae as well as additional toxin sequences from the Colubrinae. The large body of data on molecular masses and retention times thus assembled demonstrates a hitherto unsuspected diversity of toxins in all lineages, having implications ranging from clinical management of envenomings to venom evolution to the use of isolated toxins as leads for drug design and development. Although definitive assignment of a toxin to a protein family can only be done through demonstrated structural studies such as N-terminal sequencing, the molecular mass data complemented by LC retention information, presented here, do permit formulation of reasonable hypotheses concerning snake venom evolution and potential clinical effects to a degree not possible till now, and some hypotheses of this kind are proposed here. The data will also be useful in biodiscovery. 相似文献
4.
5.
Fry B Silva SR Kendall C Anderson RK 《Rapid communications in mass spectrometry : RCM》2002,16(9):854-858
Elemental analyzers have been successfully coupled to stable-isotope-ratio mass spectrometers for online measurements of the delta(34)S isotopic composition of plants, animals and soils. We found that the online technology for automated delta(34)S isotopic determinations did not yield reproducible oxygen isotopic compositions in the SO(2) produced, and as a result calculated delta(34)S values were often 1-3 per thousand too high versus their correct values, particularly for plant and animal samples with high C/S ratio. Here we provide empirical and analytical methods for correcting the S isotope values for oxygen isotope variations, and further detail a new SO(2)-SiO(2) buffering method that minimizes detrimental oxygen isotope variations in SO(2). 相似文献
6.
Fry BG Wickramaratna JC Hodgson WC Alewood PF Kini RM Ho H Wüster W 《Rapid communications in mass spectrometry : RCM》2002,16(6):600-608
Death adders (genus Acanthophis) are unique among elapid snakes in both morphology and venom composition. Despite this genus being among the most divergent of all elapids, the venom has been historically regarded as relatively quite simple. In this study, liquid chromatography/mass spectrometry (LC/MS) analysis has revealed a much greater diversity in venom composition, including the presence of molecules of novel molecular weights that may represent a new class of venom component. Furthermore, significant variation exists between species and populations, which allow for the LC/MS fingerprinting of each species. Mass profiling of Acanthophis venoms clearly demonstrates the effectiveness of this technique which underpins fundamental studies ranging from chemotaxonomy to drug design. 相似文献
7.
A. Bergier H. Gennow S. Nilsson J. Norrby W. Evans J. R. Fry P. Mason H. Muirhead H. Fenker J. Marraffino S. Reucroft C. Roos M. S. Webster 《Zeitschrift fur Physik C Particles and Fields》1980,5(4):265-274
We present data on \(\bar pn\) and π? n collisions obtained from an exposure of the 30′' FNAL deuterium filled bubble chamber to a mixed \({{\bar p} \mathord{\left/ {\vphantom {{\bar p} {\pi ^ - }}} \right. \kern-0em} {\pi ^ - }}\) beam with a momentum of 100 GeV/c. We find that in 17±2% of the collisions with the antiproton there is an interaction on the spectator while for the collisions with π? mesons the corresponding number is 15±2%. The \(\bar pn\) and π? n multiplicity distributions have average charged multiplicities of 6.46±0.07 and 6.53±0.08 respectively. The average multiplicities for both types of interactions are slightly smaller than those for the corresponding reactions on hydrogen by an amount that is the same as observed at other energies. As an estimate of \(\bar pn\) annihilation we have calculated the difference \(\sigma _n (\bar pn) - \sigma _n (pn)\) for each prong numbern. We find an average multiplicity of 9±1, a value close to that for \(\bar pp\) annihilation at the same energy. combining our data with lower energy \(\bar pn\) annihilation data, we observe that the average negative multiplicity is systematically larger than that for \(\bar pp\) annihilation similar to the difference between neutron and proton target data with other beam projectiles. 相似文献
8.
The anodic oxidation of methyl 3-phenyl-2-dimethylsilylpropionate occurs at a potential almost 1 V positive of that required to oxidize other alpha-silyl esters. Semiempirical and ab initio calculations on the model compound 1-phenyl-2-trimethylsilylethane indicate that electron removal from these two compounds is highly stereoelectronically dependent. Both molecules exist almost exclusively in a conformation in which the phenyl group and silicon atom are anti and the side chain is perpendicular to the aromatic ring. This conformation has a higher energy HOMO orbital and lower computed ionization potential than the only other significantly populated conformation of 1-phenyl-2-trimethylsilylethane. Finally, the ab initio calculations show that in the cation radical of this model compound the ipso carbon of the aromatic ring and the side chain carbon bound to silicon draw significantly closer together than in the neutral species; an electrostatic potential map of the cation radical shows that the ipso carbon bears the highest degree of positive charge of any of the benzenoid carbons. We interpret these data, taken together, as an indication that this cation radical is stabilized by overlap of the rear lobe of the carbon-silicon bond with the p-orbital of the ipso carbon. 相似文献
9.
Optical fiber (OF) sensors are often limited by the immobilization technique used to associate a specific sensing ligand with the OF surface. This is particularly true when the ligand is biologically active as, for example, in the case of immobilized haptens or antibodies. The dynamic modification protocol is a regenerable and experimentally simple way to immobilize a variety of sensing molecules on an OF surface. Furthermore, the protocol is immune to hydrolysis and not limited by diffusion through a membrane or sol–gel. In this publication the approach is extended by immobilizing the hydrophobic hapten (octadecyl 6-(2,4 dinitrophenyl)aminohexanoic acid) as a means to prepare an OF sensor for antibodies specific for 2,4 dinitrophenyl (DNP). The LOD for anti-DNP is 0.5 nanomolar and the Kapparent is 1.0±0.2×106. Nonspecific antibody adsorption is problematic in this sensing approach and was found to limit the quantitative capabilities of the sensor. However, time discrimination can be used to allow the nonspecific antibody to desorb prior to measurement thus minimizing the influence of nonspecific binding on sensor performance. 相似文献
10.
Fry HC Scaltrito DV Karlin KD Meyer GJ 《Journal of the American Chemical Society》2003,125(39):11866-11871
The observation and fast time-scale kinetic determination of a primary dioxygen-copper interaction have been studied. The ability to photorelease carbon monoxide from [Cu(I)(tmpa)(CO)](+) in mixtures of CO and O(2) in tetrahydrofuran (THF) between 188 and 218 K results in the observable formation of a copper-superoxide species, [Cu(II)(tmpa)(O(2)(-))](+) lambda(max) = 425 nm. Via this "flash-and-trap" technique, temperature-dependent kinetic studies on the forward reaction between dioxygen and [Cu(I)(tmpa)(thf)](+) afford activation parameters DeltaH = 7.62 kJ/mol and DeltaS = -45.1 J/mol K. The corresponding reverse reaction proceeds with DeltaH = 58.0 kJ/mol and DeltaS = 105 J/mol K. Overall thermodynamic parameters are DeltaH degrees = -48.5 kJ/mol and DeltaS degrees = -140 J/mol K. The temperature-dependent data allowed us to determine the room-temperature second-order rate constant, k(O2) = 1.3 x 10(9) M(-1) s(-1). Comparisons to copper and heme proteins and synthetic complexes are discussed. 相似文献