全文获取类型
收费全文 | 3271篇 |
免费 | 68篇 |
国内免费 | 13篇 |
专业分类
化学 | 2249篇 |
晶体学 | 39篇 |
力学 | 45篇 |
数学 | 194篇 |
物理学 | 825篇 |
出版年
2023年 | 15篇 |
2021年 | 26篇 |
2020年 | 38篇 |
2019年 | 48篇 |
2018年 | 34篇 |
2017年 | 28篇 |
2016年 | 55篇 |
2015年 | 59篇 |
2014年 | 77篇 |
2013年 | 180篇 |
2012年 | 157篇 |
2011年 | 168篇 |
2010年 | 96篇 |
2009年 | 116篇 |
2008年 | 152篇 |
2007年 | 174篇 |
2006年 | 165篇 |
2005年 | 182篇 |
2004年 | 184篇 |
2003年 | 153篇 |
2002年 | 144篇 |
2001年 | 77篇 |
2000年 | 66篇 |
1999年 | 31篇 |
1998年 | 48篇 |
1997年 | 48篇 |
1996年 | 63篇 |
1995年 | 63篇 |
1994年 | 48篇 |
1993年 | 45篇 |
1992年 | 45篇 |
1991年 | 44篇 |
1990年 | 48篇 |
1989年 | 46篇 |
1988年 | 29篇 |
1987年 | 34篇 |
1986年 | 20篇 |
1985年 | 34篇 |
1984年 | 29篇 |
1983年 | 17篇 |
1982年 | 16篇 |
1981年 | 23篇 |
1980年 | 21篇 |
1979年 | 18篇 |
1978年 | 26篇 |
1977年 | 21篇 |
1976年 | 19篇 |
1975年 | 14篇 |
1974年 | 18篇 |
1973年 | 26篇 |
排序方式: 共有3352条查询结果,搜索用时 15 毫秒
11.
Takashi Yoshitake Ryuji Iizuka Kaoru Fujino Osamu Inoue Kenji Yamagata Hitoshi Nohta Masatoshi Yamaguchi 《Analytical sciences》2004,20(12):1687-1690
An improved high-performance liquid-chromatographic (HPLC) assay for the simultaneous determination of serotonin (5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA) in human urine is reported. Following the automated precolumn derivatization of urinary 5-HT and 5-HIAA with benzylamine, the derivatives are separated by isocratic elution on a reversed-phase C18 semi-microbore column, and are fluorometrically detected at an excitation wavelength of 345 nm and an emission wavelength of 480 nm. The detection limits of 5-HT and 5-HIAA are 7 and 5 nmol/l in urine (0.7 and 0.5 fmol/20-microl injection). The proposed automatic method permits a highly selective and sensitive determination of 5-HT and 5-HIAA in human urine without any sample purification. 相似文献
12.
Takayuki Abe 《Mathematical Methods in the Applied Sciences》2004,27(9):1007-1048
This paper is concerned with the standard Lp estimate of solutions to the resolvent problem for the Stokes operator on an infinite layer with ‘Neumann–Dirichlet‐type’ boundary condition. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
13.
Y. Abe 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):143-148
Based on the theory of the compound nucleus reaction, a brief review is given on the special aspects of the reaction dynamics
in the synthesis of the superheavy elements (SHE), where the fusion probability is the most unknown factor. A new viewpoint
of the fusion reaction is proposed that it consists of two processes; the first process up to the contact of two nuclei of
the incident channel and the second one of a dynamical evolution to the spherical compound nucleus from the contact configuration.
The fusion probability is, thus, given as a product of a contact probability and a formation probability. Analytic studies
of the latter probability are discussed in the one-dimensional model, where a simple expression is given to the so-called
extra-push energy in terms of the reduced friction, the curvature parameter of the conditional saddle point and the nuclear
temperature. Preliminary results of numerical analyses of the contact probability are given, using the surface friction model
(SFM). Remarks are given on the present status of our knowledge and for future developments.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
14.
Masaharu Asano Jinhua Chen Yasunari Maekawa Takahiro Sakamura Hitoshi Kubota Masaru Yoshida 《Journal of polymer science. Part A, Polymer chemistry》2007,45(13):2624-2637
A novel process comprising the UV‐induced photografting of styrene into poly(tetrafluoroethylene) (PTFE) films and subsequent sulfonation has been developed for preparing proton‐conducting membranes. Although under UV irradiation the initial radicals were mainly generated on the surface of the PTFE films by the action of photosensitizers such as xanthone and benzoyl peroxide, the graft chains were readily propagated into the PTFE films. The sulfonation of the grafted films was performed in a chlorosulfonic acid solution. Fourier transform infrared and scanning electron microscopy were used to characterize the grafted and sulfonated membranes. With a view to use in fuel cells, the proton conductivity, water uptake, and mechanical properties of the prepared membranes were measured. Even through the degree of grafting was lower than 10%, the proton conductivity in the thickness direction of the newly prepared membranes could reach a value similar to that of a Nafion membrane. In comparison with γ‐ray radiation grafting, UV‐induced photografting is very simple and safe and is less damaging to the membranes because significant degradation of the PTFE main chains can be avoided. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2624–2637, 2007 相似文献
15.
Ilda Abe Rafael E. de Ges Jos L. Fabris Hypolito J. Kalinowski Mrcia Müller Meire C. Fugihara Rosane Falate Barbara W. Diesel Ricardo C. Kamikawachi Carmen L. Barbosa 《Optics and Lasers in Engineering》2003,39(5-6):537-548
In this work, we report production and modelling of both Bragg gratings and rocking filters in high birefringence fibre optics. Bragg gratings are produced by UV (257.0 nm) external interferometric exposition of a frequency-doubled Ar+ ion laser, whereas for rocking filters formation the visible Ar+ ion laser lines in 488.0 and 514.5 nm are used in an internal method. The spectral characteristics due to the birefringence properties are studied through numerical methods and experimental techniques. The spectral responsivity of the structures under temperature changes and stress application is presented. 相似文献
16.
A convergent synthesis of the key synthetic intermediate of hemibrevetoxin B was achieved via the intramolecular allylation of an α-chloroacetoxy ether and subsequent ring-closing metathesis. 相似文献
17.
On a certain move generating link-homology 总被引:4,自引:0,他引:4
Dedicated to Professor Kunio Murasugi on his sixtieth birthday 相似文献
18.
Midori Kobayashi Hitoshi Awoki Yoshimi Nakazaki Gisaku Nakamura 《Graphs and Combinatorics》1989,5(1):243-244
In this paper, a perfect one-factorization ofK
36 is given, which is factor-1-rotational. 相似文献
19.
Embeddings of the CAR (canonical anticommutation relations) algebra of fermions into the Cuntz algebra ?2 (or ?2
d
more generally) are presented by using recursive constructions. As a typical example, an embedding of CAR onto the U(1)-invariant subalgebra of ?2 is constructed explicitly. Generalizing this construction to the case of ?2
p
, an embedding of CAR onto the U(1)-invariant subalgebra of ?2
p
is obtained. Restricting a permutation representation of the Cuntz algebra, we obtain the Fock representation of CAR. We
apply the results to embed the algebra of parafermions of order p into ?2
p
according to Green's ansatz.
Received: 3 September 2001 / Accepted: 19 January 2002 相似文献
20.
Hideyuki Yoshida Yuki Ohno Kenichiro Yoshikuni Kenichiro Todoroki Hitoshi Nohta Masatoshi Yamaguchi 《Analytical sciences》2003,19(2):317-319
A simple and sensitive fluorometric high-performance liquid chromatographic method was developed for the determination of midodrine in human plasma. After liquid-liquid extraction from plasma, the drug and 2-phenylglycinol (internal standard) were convened into the corresponding fluorescent derivatives by reaction with 3,4-dihydro-6,7-dimethoxy-4-methyl-3-oxoquinoxaline-2-carbonyl chloride, a fluorescence derivatization reagent for amines. The derivatives were separated within 30 min on a reversed-phase column using isocratic elution with acetonitrile-methanol-water (10:30:60, v/v) and were detected spectrofluorometrically at 485 nm with excitation at 400 nm. The detection limit for midodrine was 0.3 pmol (76 pg) per mL plasma at a signal-to-noise ratio of 3. 相似文献