全文获取类型
收费全文 | 834篇 |
免费 | 12篇 |
国内免费 | 8篇 |
专业分类
化学 | 502篇 |
晶体学 | 9篇 |
力学 | 27篇 |
数学 | 118篇 |
物理学 | 198篇 |
出版年
2021年 | 10篇 |
2020年 | 5篇 |
2018年 | 9篇 |
2016年 | 9篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 29篇 |
2012年 | 41篇 |
2011年 | 43篇 |
2010年 | 19篇 |
2009年 | 19篇 |
2008年 | 41篇 |
2007年 | 43篇 |
2006年 | 46篇 |
2005年 | 25篇 |
2004年 | 35篇 |
2003年 | 20篇 |
2002年 | 23篇 |
2001年 | 29篇 |
2000年 | 22篇 |
1999年 | 12篇 |
1998年 | 7篇 |
1997年 | 24篇 |
1996年 | 18篇 |
1995年 | 11篇 |
1994年 | 15篇 |
1993年 | 16篇 |
1992年 | 11篇 |
1991年 | 17篇 |
1990年 | 15篇 |
1989年 | 12篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 11篇 |
1978年 | 11篇 |
1977年 | 10篇 |
1976年 | 14篇 |
1975年 | 9篇 |
1974年 | 13篇 |
1973年 | 5篇 |
1972年 | 6篇 |
1971年 | 6篇 |
1970年 | 5篇 |
1967年 | 5篇 |
排序方式: 共有854条查询结果,搜索用时 46 毫秒
101.
James L. Reid 《Physics letters. A》1984,103(9):403-404
Analytic linearization maps are found for autonomous systems of n coupled Bernoulli equations of a certain class. The class of equations is determined by the requirement that the nonlinear system linearize to its linear part. These equations have applications as models for interacting biological systems. 相似文献
102.
103.
Mitchem L Buajarern J Ward AD Reid JP 《The journal of physical chemistry. B》2006,110(28):13700-13703
We demonstrate that the coagulation of two aerosol droplets of different chemical composition can be studied directly through the unique combination of optical tweezers and Raman spectroscopy. Multiple optical traps can be established, allowing the manipulation of multiple aerosol droplets. Spontaneous Raman scattering allows the characterization of droplet composition and mixing state, permitting the phase segregation of immiscible components in multiphase aerosol to be investigated with spatial resolution. Stimulated Raman scattering allows the integrity of the droplet and uniformity of refractive index to be probed. The combination of these spectroscopic probes with optical tweezers is shown to yield unprecedented detail in studies of the coagulation of decane and water droplets. 相似文献
104.
Tao C Deselnicu M Fan H Mukarakate C Ionescu I Reid SA 《Physical chemistry chemical physics : PCCP》2006,8(6):707-713
To further investigate the Renner-Teller (RT) effect and barriers to linearity and dissociation in the simplest singlet carbene, we recorded fluorescence excitation spectra of bands involving the pure bending levels 2(n)(0) with n = 0-9 and the combination states 1(1)(0)2(n)(0) with n = 1-8 and 2(n)(0)3(1)(0) with n = 0-5 in the A(1)A'<-- X(1)A' system of CDF, in addition to some weak hot bands. The spectra were measured under jet-cooled conditions using a pulsed discharge source, and rotationally analyzed to yield precise values for the band origins and rotational constants; fluorescence lifetimes were also measured to probe for lifetime lengthening effects due to the RT interaction. The derived A state parameters are compared with previous results for CHF and with predictions of ab initio electronic structure theory. The approach to linearity in the A state is evidenced in a sharp increase in the A rotational constant with bending excitation, and a minimum in the vibrational intervals near 2(9). A fit of the vibrational intervals for the pure bending levels yields an A state barrier to linearity in good agreement both with that previously derived for CHF and ab initio predictions. From the spectra and lifetime measurements, the onset of extensive RT perturbations is found to occur at a higher energy than in CHF, consistent with the smaller A constant. 相似文献
105.
James E. Reid 《Geometriae Dedicata》2018,197(1):173-192
Let J be the limit set of an iterated function system in \(\mathbb {R}^d\) satisfying the open set condition. It is well known that the h-dimensional packing measure of J is positive and finite when h is given by Hutchinson’s formula. However, it may be hard to find a formula for the h-dimensional packing measure of J. We introduce the super separation condition and use it to reduce the problem of computing the packing measure to checking densities of a finite number of balls around each point in the limit set. We then use this fact to find formulas for the packing measure of a class of Cantor sets in \(\mathbb {R}\), a class of fractals based on regular convex polygons in \(\mathbb {R}^2\), and a class of fractals based on regular simplexes in \(\mathbb {R}^d\) for \(d \ge 3\). 相似文献
106.
Talmage J. Reid Jakayla Robbins Haidong Wu Xiangqian Zhou 《Discrete Mathematics》2010,310(17-18):2389-2397
107.
108.
Dr. Joshua E. S. J. Reid Pedro H. G. Aquino Dr. Adam J. Walker Dr. Peter B. Karadakov Dr. Seishi Shimizu 《Chemphyschem》2019,20(11):1538-1544
The kinetics of Diels-Alder (DA) reactions in water has been known to be altered by salts for a long time. Yet the question how salts influence the reaction rate, either as rate-enhancing or rate-reducing additives, has so far remained unresolved. Conflicting hypotheses involve (i) indirect salt contributions through the modulation of internal pressure and (ii) making (or breaking) of the so-called “water-structure” by salts that strengthen (or weaken) the hydrophobic effect. In contrast to the qualitative nature of these hypotheses, here we answer this question quantitatively through a combination of transition state theory and fluctuation adsorption-solvation theory (FAST) using the DA reaction between anthracene-9-carbinol and N-ethylmaleimide as an example. We show that rate enhancement is driven by the salting out of the hydrophobic reactant, while rate-enhancing salts exhibit stronger affinity to the transition state. 相似文献
109.
Scarlett Puebla-Barragan Emiley Watson Charlotte van der Veer John A. Chmiel Charles Carr Jeremy P. Burton Mark Sumarah Remco Kort Gregor Reid 《Molecules (Basel, Switzerland)》2021,26(15)
Lactobacillus crispatus is the dominant species in the vagina of many women. With the potential for strains of this species to be used as a probiotic to help prevent and treat dysbiosis, we investigated isolates from vaginal swabs with Lactobacillus-dominated and a dysbiotic microbiota. A comparative genome analysis led to the identification of metabolic pathways for synthesis and degradation of three major biogenic amines in most strains. However, targeted metabolomic analysis of the production and degradation of biogenic amines showed that certain strains have either the ability to produce or to degrade these compounds. Notably, six strains produced cadaverine, one produced putrescine, and two produced tyramine. These biogenic amines are known to raise vaginal pH, cause malodour, and make the environment more favourable to vaginal pathogens. In vitro experiments confirmed that strains isolated from women with a dysbiotic vaginal microbiota have higher antimicrobial effects against the common urogenital pathogens Escherichia coli and Enterococcus faecium. The results indicate that not all L. crispatus vaginal strains appear suitable for probiotic application and the basis for selection should not be only the overall composition of the vaginal microbiota of the host from which they came, but specific biochemical and genetic traits. 相似文献
110.
The Role of Torsional Dynamics on Hole and Exciton Stabilization in π‐Stacked Assemblies: Design of Rigid Torsionomers of a Cofacial Bifluorene 下载免费PDF全文
Dr. Denan Wang Dr. Maxim V. Ivanov Dr. Damian Kokkin John Loman Jin‐Zhe Cai Prof. Scott A. Reid Prof. Rajendra Rathore 《Angewandte Chemie (International ed. in English)》2018,57(27):8189-8193
Exciton and charge delocalization across π‐stacked assemblies is of importance in biological systems and functional polymeric materials. To examine the requirements for exciton and hole stabilization, cofacial bifluorene ( F 2) torsionomers were designed, synthesized, and characterized: unhindered (model) Me F 2, sterically hindered tBu F 2, and cyclophane‐like C F 2, where fluorenes are locked in a perfect sandwich orientation via two methylene linkers. This set of bichromophores with varied torsional rigidity and orbital overlap shows that exciton stabilization requires a perfect sandwich‐like arrangement, as seen by strong excimeric‐like emission only in C F 2 and Me F 2. In contrast, hole delocalization is less geometrically restrictive and occurs even in sterically hindered tBu F 2, as judged by 160 mV hole stabilization and a near‐IR band in the spectrum of its cation radical. These findings underscore the diverse requirements for charge and energy delocalization across π‐stacked assemblies. 相似文献