全文获取类型
收费全文 | 6816篇 |
免费 | 138篇 |
国内免费 | 41篇 |
专业分类
化学 | 5050篇 |
晶体学 | 26篇 |
力学 | 135篇 |
综合类 | 1篇 |
数学 | 924篇 |
物理学 | 859篇 |
出版年
2021年 | 57篇 |
2020年 | 61篇 |
2019年 | 58篇 |
2018年 | 45篇 |
2016年 | 89篇 |
2015年 | 89篇 |
2014年 | 144篇 |
2013年 | 268篇 |
2012年 | 278篇 |
2011年 | 308篇 |
2010年 | 176篇 |
2009年 | 155篇 |
2008年 | 247篇 |
2007年 | 291篇 |
2006年 | 289篇 |
2005年 | 254篇 |
2004年 | 222篇 |
2003年 | 212篇 |
2002年 | 217篇 |
2001年 | 103篇 |
2000年 | 103篇 |
1999年 | 73篇 |
1998年 | 61篇 |
1997年 | 81篇 |
1996年 | 93篇 |
1995年 | 73篇 |
1994年 | 86篇 |
1993年 | 69篇 |
1992年 | 67篇 |
1991年 | 67篇 |
1990年 | 63篇 |
1989年 | 68篇 |
1988年 | 55篇 |
1987年 | 62篇 |
1986年 | 69篇 |
1985年 | 108篇 |
1984年 | 108篇 |
1983年 | 68篇 |
1982年 | 100篇 |
1981年 | 94篇 |
1980年 | 96篇 |
1979年 | 101篇 |
1978年 | 115篇 |
1977年 | 99篇 |
1976年 | 89篇 |
1975年 | 63篇 |
1974年 | 62篇 |
1973年 | 76篇 |
1972年 | 50篇 |
1971年 | 63篇 |
排序方式: 共有6995条查询结果,搜索用时 228 毫秒
31.
32.
Sonya V. Roberson Albert J. Fahey Amit Sehgal Alamgir Karim 《Applied Surface Science》2002,200(1-4):150-164
We present a simple method for chemical modification of chlorosilane self-assembled monolayers (SAMs) on Si surfaces by exposure to a gradient of UV-ozone radiation to create stable substrates with a range of contact angles (θH2O≈5–95°) and surface energies on a single substrate. These gradient energy substrates are developed to potentially generate libraries for combinatorial studies of thin film phenomenology, where a systematic variation of interfacial surface energy represents one of the significant parameters along one axis. The graded oxidation process presents a systematic variation of surface chemical composition. We have utilized contact angle measurements and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to investigate this variation for a series of ions, among which are SiCH3+, SiOH+ and COOH−. We show that the macroscopic measurements of surface free energy/contact angle correlate with the detailed analysis of surface chemistry (as assessed by ToF-SIMS) on these test substrates. 相似文献
33.
M. Le Vassor D’yerville D. Monge D. Cassagne J. P. Albert 《Optical and Quantum Electronics》2002,34(5-6):445-454
We present here a tight-binding-like modelling of two-dimensional (2D) photonic crystals (PCs). Adopted from solid-state physics,
the concept of generalized Wannier functions is used to construct a localized state basis that allows a parameter-free ab
initio study of defects in PCs. We demonstrate here for a 2D triangular lattice of dielectric rods in air, the existence of
this localized basis and the possibility to study large scale complex dielectric structures deviating from periodicity. Specific
numerical simulations on a split waveguide embedded in this triangular lattice are performed, and they demonstrate the superiority
of this method over plane wave based techniques. 相似文献
34.
Greg Gillen Albert Fahey Matt Wagner Christine Mahoney 《Applied Surface Science》2006,252(19):6537-6541
Thin monolayer and bilayer films of spin cast poly(methyl methacrylate) (PMMA), poly(2-hydroxyethyl methacrylate) (PHEMA), poly(lactic) acid (PLA) and PLA doped with several pharmaceuticals have been analyzed by dynamic SIMS using SF5+ polyatomic primary ion bombardment. Each of these systems exhibited minimal primary beam-induced degradation under cluster ion bombardment allowing molecular depth profiles to be obtained through the film. By combing secondary ion imaging with depth profiling, three-dimensional molecular image depth profiles have been obtained from these systems. In another approach, bevel cross-sections are cut in the samples with the SF5+ primary ion beam to produce a laterally magnified cross-section of the sample that does not contain the beam-induced damage that would be induced by conventional focussed ion beam (FIB) cross-sectioning. The bevel surface can then be examined using cluster SIMS imaging or other appropriate microanalysis technique. 相似文献
35.
36.
Rudolf Andreasch 《Monatshefte für Chemie / Chemical Monthly》1887,8(1):407-424
Ohne Zusammenfassung 相似文献
37.
Albert Cohen Sidi Mahmoud Kaber Siegfried Mü ller Marie Postel. 《Mathematics of Computation》2003,72(241):183-225
The use of multiresolution decompositions in the context of finite volume schemes for conservation laws was first proposed by A. Harten for the purpose of accelerating the evaluation of numerical fluxes through an adaptive computation. In this approach the solution is still represented at each time step on the finest grid, resulting in an inherent limitation of the potential gain in memory space and computational time. The present paper is concerned with the development and the numerical analysis of fully adaptive multiresolution schemes, in which the solution is represented and computed in a dynamically evolved adaptive grid. A crucial problem is then the accurate computation of the flux without the full knowledge of fine grid cell averages. Several solutions to this problem are proposed, analyzed, and compared in terms of accuracy and complexity.
38.
Rudolf Sturm 《Mathematische Annalen》1882,19(4):461-486
Ohne Zusammenfassung 相似文献
39.
Rudolf Ofner 《Monatshefte für Chemie / Chemical Monthly》1904,25(6):611-620
Ohne Zusammenfassung 相似文献
40.
Currently, most combinatorial optimisation problems have to be solved, if the optimum solution is sought, using general techniques
to explore the space of feasible solutions and, more specifically, through exploratory enumerative procedures in trees and
search graphs. We propose Branch and Win, a general formulation for understanding and synthesising the different tree search
procedures that have been presented in the literature of operations research as well as in that of artificial intelligence.
Several general ideas are also presented, whose application allows designing new hybrid search algorithms, in order to implement
the procedure. 相似文献