全文获取类型
收费全文 | 209篇 |
免费 | 11篇 |
专业分类
化学 | 134篇 |
力学 | 7篇 |
数学 | 28篇 |
物理学 | 51篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 11篇 |
2013年 | 9篇 |
2012年 | 14篇 |
2011年 | 25篇 |
2010年 | 10篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 8篇 |
2005年 | 11篇 |
2004年 | 11篇 |
2003年 | 5篇 |
2002年 | 8篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1960年 | 1篇 |
1934年 | 1篇 |
1919年 | 1篇 |
1913年 | 2篇 |
1906年 | 1篇 |
1893年 | 1篇 |
1882年 | 1篇 |
排序方式: 共有220条查询结果,搜索用时 31 毫秒
101.
This review discusses the development and recent advances of probes encapsulated by biologically localized embedding (PEBBLEs), and in particular the application of PEBBLEs as ion sensors. PEBBLEs allow for minimally intrusive sensing of ions in cellular environments due to their small size (20 to 600 nm in diameter) and protect the sensing elements (i.e. fluorescent dyes) by encapsulating them within an inert matrix. The selectivity and sensitivity of these nanosensors are comparable to those of macroscopic ion selective optodes, and electrodes, while the response time and absolute detection limit are significantly better. This paper discusses the principles guiding PEBBLE design including synthesis, characterization, diversification, the advantages and limitations of the sensors, cellular applications and future directions of PEBBLE research. 相似文献
102.
The lower band-edge energy of the first single exciton of naphthalene has been determined as a function of concentration in a C10H8/C10D8 alloy. Experimentally, the vibronic 0–512 fluorescence at 2 K and 1 cm?1 resolution has been measured. Theoretically, the coherent potential approximation (CPA) and the negative factor counting (NFC) results have been derived from the work of Hong and Kopelman. Agreement is good within the experimental and computational uncertainties (2–3 cm?1). 相似文献
103.
The phonon Raman spectra of crystals of dimethylacetylene, perdeutero-dimethylacetylene and their mixtures have been investigated down to 20°K. The high temperature phase shows only one line and the low temperature phase only two. Neither of these is related to the Rz (methyl) rotation, which seems to remain practically free. However, the latter motion is found to be restricted in a newly discovered metastable phase, which is reported here first, displaying 5–6 phonon bands. The well-known λ-point transition appears little related to methyl rotations. The internal rotation of dimethylacetylene seems to stay practically free down to 20°K in the stable phases. 相似文献
104.
An experimental investigation of one-dimensional, diffusion-limited A+BC chemical reactions is reported. The persistence of reactant segregation and the formation of a depletion zone is observed and expressed in terms of the universal time exponents: (motion of the boundary zone), (width of instantaneous product formation zone), (rate of instantaneous local formation of product), (rate of instantaneous global formation of product), etc. There is good agreement with the recently predicted and/or simulated values:=1/2,=1/6,=2/3,=1/2, in contrast to classical predictions (=0,=1/2,=0,=–1/2). Furthermore, classically the segregation would not be preserved and there would be no formation of a depletion zone and no motion (just dissipation) of the reaction zone. We also discuss the relations to electrode oxidation-reduction reactions, i.e., A+CC where C is a catalyst, electrode, or trap. 相似文献
105.
Katja Lindenberg Wen -Shyan Sheu Raoul Kopelman 《Journal of statistical physics》1991,65(5-6):1269-1283
We review our scaling results for the diffusion-limited reactions A + A 0 and A+B0 on Euclidean and fractal geometries. These scaling results embody the anomalies that are observed in these reactions in low dimensions; we collect these observations under a single phenomenological umbrella. Although we are not able to fix all the exponents in our scaling expressions from first principles, we establish bounds that bracket the observed numerical results. 相似文献
106.
Alkanediyl-alpha,omega-bis(dimethylalkylammonium bromide) surfactants: II. Krafft temperature and melting temperature 总被引:1,自引:0,他引:1
Zana R 《Journal of colloid and interface science》2002,252(1):259-261
The melting temperature T(M) of two series of dimeric (gemini) surfactants, the alkanediyl-alpha,omega-bis(dodecyl and hexadecyl dimethylammonium bromide), referred to as 12-s-12 and 16-s-16, respectively (s = carbon number of the alkanediyl spacer), and the Krafft temperature T(K) of 1 wt% aqueous solutions of these surfactants have been measured. The melting temperature of the solid surfactant increases with the carbon number m of the alkyl chain. For each surfactant series, T(M) goes through a maximum at s close to 5, irrespective of the value of m. For the 12-s-12 series, T(M) goes through a minimum at s = 10 to 12. At a constant value of s, the value of T(K) increases with m. The variations of T(M) and T(K) with s show some correlation, with T(K) decreasing when T(M) increases and vice versa. The results are discussed in relation to the solution properties of the investigated surfactants. 相似文献
107.
108.
Micelles formed in water from ammonium dodecyl sulfate (AmDS) are characterized using time-resolved fluorescence quenching (TRFQ), electron paramagnetic resonance (EPR), conductivity, Krafft temperature, and density measurements. TRFQ was used to measure the aggregation number, N, and the quenching rate constant of pyrene by dodecylpyridinium chloride, k(Q). N depends only on the concentration (C(aq)) of ammonium ions in the aqueous phase whether these counterions are derived from the surfactant alone or from the surfactant plus added ammonium chloride as follows: N = N0(C(aq)/cmc0)(gamma), where N0 is the aggregation number at the critical micelle concentration in the absence of added salt, cmc0, and is equal to 77, 70, and 61 at 16, 25, and 35 degrees C, respectively. The exponent gamma = 0.22 is independent of temperature in the range 16 to 35 degrees C. The fact that N depends only on C(aq) permits the determination of the micelle ionization degree (alpha) by employing various experimental approaches to exploit a recent suggestion (J. Phys. Chem. B 2001, 105, 6798) that N depends only on C(aq). Utilizing various combinations of salt and surfactant, values of alpha were obtained by finding common curves as a function of C(aq) of the following experimental results: the Krafft temperature, N, k(Q), the microviscosity of the Stern layer determined from the rotational correlation time of a spin probe, 5-doxyl stearic acid methyl ester, and the spin-probe sensed hydration of the micelle surface. The values of alpha, determined from applying the aggregation number-based definition of alpha to all of these quantities, were within experimental uncertainty of the values alpha = 0.19, 0.20, and 0.21 derived from conductivity measurements at 16, 25, and 35 degrees C, respectively. The volume fraction of the Stern layer occupied by water decreases as N increases. For AmDS micelles, both the hydration and its decrease are predicted by a simple theory of micelle hydration by fixing the parameters of the theory for sodium dodecyl sulfate and employing no further adjustable parameters. For a given value of N, the hydration decreases as the temperature increases. 相似文献
109.
110.
The Locally Conservative Galerkin (LCG) Method — a Discontinuous Methodology Applied to a Continuous Framework
下载免费PDF全文
![点击此处可从《advances in applied mathematics and mechanics.》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Rhodri L. T. Bevan Raoul vanLoon & Perumal Nithiarasu 《advances in applied mathematics and mechanics.》2009,1(3):319-340
This paper presents a comprehensive overview of the element-wise
locally conservative Galerkin (LCG) method. The LCG method was
developed to find a method that had the advantages of the
discontinuous Galerkin methods, without the large computational and
memory requirements. The initial application of the method is
discussed, to the simple scalar transient convection-diffusion
equation, along with its extension to the Navier-Stokes equations
utilising the Characteristic Based Split (CBS) scheme. The
element-by-element solution approach removes the standard finite
element assembly necessity, with an face flux providing continuity
between these elemental subdomains. This face flux provides explicit
local conservation and can be determined via a simple small
post-processing calculation. The LCG method obtains a unique
solution from the elemental contributions through the use of simple
averaging. It is shown within this paper that the LCG method
provides equivalent solutions to the continuous (global) Galerkin
method for both steady state and transient solutions. Several
numerical examples are provided to demonstrate the abilities of the
LCG method. 相似文献