全文获取类型
收费全文 | 9151篇 |
免费 | 774篇 |
国内免费 | 801篇 |
专业分类
化学 | 2520篇 |
晶体学 | 100篇 |
力学 | 973篇 |
综合类 | 149篇 |
数学 | 4687篇 |
物理学 | 2297篇 |
出版年
2023年 | 76篇 |
2022年 | 150篇 |
2021年 | 201篇 |
2020年 | 291篇 |
2019年 | 241篇 |
2018年 | 259篇 |
2017年 | 244篇 |
2016年 | 350篇 |
2015年 | 241篇 |
2014年 | 427篇 |
2013年 | 751篇 |
2012年 | 385篇 |
2011年 | 474篇 |
2010年 | 404篇 |
2009年 | 511篇 |
2008年 | 549篇 |
2007年 | 616篇 |
2006年 | 496篇 |
2005年 | 441篇 |
2004年 | 416篇 |
2003年 | 427篇 |
2002年 | 342篇 |
2001年 | 297篇 |
2000年 | 255篇 |
1999年 | 246篇 |
1998年 | 207篇 |
1997年 | 172篇 |
1996年 | 176篇 |
1995年 | 147篇 |
1994年 | 135篇 |
1993年 | 96篇 |
1992年 | 82篇 |
1991年 | 79篇 |
1990年 | 71篇 |
1989年 | 48篇 |
1988年 | 57篇 |
1987年 | 42篇 |
1986年 | 30篇 |
1985年 | 48篇 |
1984年 | 37篇 |
1983年 | 23篇 |
1982年 | 36篇 |
1981年 | 22篇 |
1980年 | 13篇 |
1979年 | 30篇 |
1978年 | 19篇 |
1977年 | 23篇 |
1976年 | 20篇 |
1975年 | 6篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
ISSDE: A Monte Carlo implicit simulation code based on Stratonovich SDE approach of Coulomb collision 下载免费PDF全文
《中国物理 B》2021,30(9):95201-095201
A Monte Carlo implicit simulation program, Implicit Stratonovich Stochastic Differential Equations(ISSDE), is developed for solving stochastic differential equations(SDEs) that describe plasmas with Coulomb collision. The basic idea of the program is the stochastic equivalence between the Fokker–Planck equation and the Stratonovich SDEs. The splitting method is used to increase the numerical stability of the algorithm for dynamics of charged particles with Coulomb collision. The cases of Lorentzian plasma, Maxwellian plasma and arbitrary distribution function of background plasma have been considered. The adoption of the implicit midpoint method guarantees exactly the energy conservation for the diffusion term and thus improves the numerical stability compared with conventional Runge–Kutta methods. ISSDE is built with C++ and has standard interfaces and extensible modules. The slowing down processes of electron beams in unmagnetized plasma and relaxation process in magnetized plasma are studied using the ISSDE, which shows its correctness and reliability. 相似文献
12.
Anthony Blanchard Flavien Melis Fabrice Gouanvé Jean-Matthieu Brouillat Eliane Espuche 《Journal of polymer science. Part A, Polymer chemistry》2021,59(1):70-83
The influences of the molar mass (low, medium, and high) and content of poly(vinyl alcohol) (PVOH) dispersed by melt-blending in an ethylene vinyl alcohol (EVOH) copolymer on the morphology, microstructure, thermal, mechanical, and oxygen barrier properties were investigated. Multilayer films with external low-density polyethylene layers and inner EVOH/PVOH blend layer and respective monolayer films were elaborated and characterized. EVOH/PVOH blends exhibited a good compatibility because of the initial presence of PVOH segments in EVOH. The detailed quantitative analysis of the morphology performed for all blends showed that the finest dispersion was obtained with the PVOH with the lowest molar mass. The properties of the films as a function of the PVOH content and its molar mass were determined herein. Significant improvement of barrier properties was obtained at moderated water activities (up to aw = 0.6) by using the PVOH with the lowest molar mass. Compared to the neat EVOH material, the oxygen permeability coefficients decreased by a factor 2 by adding 15 vol% PVOH while the thermal and mechanical properties remained similar. 相似文献
13.
《Comptes Rendus Chimie》2015,18(5):474-477
A series of ternary CuMOR–SiO2 mixed materials were prepared by two synthesis approaches (CuMOR1–y–SiO2 and CuMOR2–y–SiO2). Extensive characterization was done for both series and some selected materials were tested in CO catalytic oxidation and NO reduction. The presence of CuMOR and SiO2 segregated phases was observed in both series by XRD, suggesting that silica formation was not inhibited by the mordenite (MOR) presence. UV–Vis results exhibited that Cu ion exchange was successfully done for CuMOR1–y–SiO2 series. In the CuMOR2–y–SiO2 series, the amount of copper was below the sensitivity limit of EDS analysis. CuMOR1–50%–SiO2 catalyst resulted with higher specific surface area and catalytic activity. A possible relation between reduction temperature, the increase in Cu plasmon excitation, and catalytic activity was observed. 相似文献
14.
WEI Qi-cai 《高校应用数学学报(英文版)》2015,(2):217-226
In this paper, with the aid of large deviation formulas established in strong topology of functional space generated by H¨older norm, we discuss the functional sample path properties of subsequence's C-R increments for a Wiener process in H¨older normThe obtained results,generalize the corresponding results of Chen and the classic Strassen's law of iterated logarithm for a Wiener process. 相似文献
15.
A back propagation artificial neural network (BPANN) prediction model for warpage of injection-molded polypropylene was developed based on an orthogonal design method. The BPANN model was trained by the input and output data obtained from the moldflow software platform simulations. It is proved that the BPANN model can predict the warpage with reasonable accuracy. Utilizing the BPANN model, the effects of the process parameters, packing pressure (Pp), melt temperature (Tme), mold temperature (Tmo), packing time (tp), cooling time (tc), and fill pressure (pf), on the warpage were investigated. The most important process parameter affecting the warpage was Pp, and the second most important was Tme. The rest of the process parameters, Tmo, tp, tc, and pf, were found to be relatively less influential. Warpage increased with elevating Tmo. In contrast, an increase in Pp and Tme caused the warpage to decrease. 相似文献
16.
17.
18.
19.
《Stochastic Processes and their Applications》2020,130(5):2596-2638
In this paper we introduce a new generalisation of the relative Fisher Information for Markov jump processes on a finite or countable state space, and prove an inequality which connects this object with the relative entropy and a large deviation rate functional. In addition to possessing various favourable properties, we show that this generalised Fisher Information converges to the classical Fisher Information in an appropriate limit. We then use this generalised Fisher Information and the aforementioned inequality to qualitatively study coarse-graining problems for jump processes on discrete spaces. 相似文献
20.
Non-equilibrium self-assembly is ubiquitous in physico-chemical and biological systems, and manifests itself at different scales, ranging from the molecular to the cosmological. The formation of microtubules, gels, cells and living beings among many others takes place through self-assembly under nonequilibrium conditions. We propose a general thermodynamic non-equilibrium model to understand the formation of assembled structures such as gels and Liesegang patterns and at the same time able to describe the kinetics and the energetics of the structure formation process. The model is supported for a global mechanism to obtain self-assembled structures from building blocks via activation, deactivation, assembly, and disassembly processes. It is proposed that the resulting structures can be characterised by a structural parameter. Our model may contribute to a better understanding of non-equilibrium self-assembly processes and give deeper insight as to how to obtain a specific structural architecture to materials, such as hydrogels which are of great importance in the design of advanced devices and novel materials. 相似文献