全文获取类型
收费全文 | 40483篇 |
免费 | 1400篇 |
国内免费 | 10篇 |
专业分类
化学 | 22652篇 |
晶体学 | 173篇 |
力学 | 856篇 |
数学 | 6548篇 |
物理学 | 11664篇 |
出版年
2023年 | 220篇 |
2021年 | 332篇 |
2020年 | 533篇 |
2019年 | 360篇 |
2018年 | 467篇 |
2017年 | 448篇 |
2016年 | 1057篇 |
2015年 | 886篇 |
2014年 | 989篇 |
2013年 | 2179篇 |
2012年 | 1736篇 |
2011年 | 2106篇 |
2010年 | 1077篇 |
2009年 | 887篇 |
2008年 | 1974篇 |
2007年 | 1933篇 |
2006年 | 1710篇 |
2005年 | 1519篇 |
2004年 | 1199篇 |
2003年 | 1033篇 |
2002年 | 958篇 |
2001年 | 806篇 |
2000年 | 716篇 |
1999年 | 493篇 |
1998年 | 430篇 |
1997年 | 446篇 |
1996年 | 546篇 |
1995年 | 489篇 |
1994年 | 506篇 |
1993年 | 588篇 |
1992年 | 496篇 |
1991年 | 371篇 |
1990年 | 417篇 |
1989年 | 336篇 |
1988年 | 356篇 |
1987年 | 359篇 |
1986年 | 317篇 |
1985年 | 495篇 |
1984年 | 491篇 |
1983年 | 454篇 |
1982年 | 466篇 |
1981年 | 478篇 |
1980年 | 425篇 |
1979年 | 396篇 |
1978年 | 437篇 |
1977年 | 409篇 |
1976年 | 370篇 |
1975年 | 357篇 |
1974年 | 331篇 |
1973年 | 344篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Periodica Mathematica Hungarica - 相似文献
62.
P. González D. Fernández J. Pou E. García J. Serra B. León M. Pérez-Amor T. Szörényi 《Applied Physics A: Materials Science & Processing》1993,57(2):181-185
A study of the gas-phase parameters involved in ArF laser induced chemical vapour deposition of silicon-oxide thin films is presented. A complete set of experiments has been performed showing the influence of the concentration of the precursor gases, N2O and SiH4, and their influence on total and partial pressures on film growth and properties. In this paper we demonstrate the ability of this LCVD method to deposit silicon oxide films of different compositions and densities by appropriate control of gas composition and total pressure. Moreover, a material specific calibration plot comprising data obtained using different preparation techniques is presented, allowing determination of the stoichiometry of SiO
x
films by using FTIR spectroscopy independently of the deposition method. For the range of processing conditions examined, the experimental results suggest that chemical processes governing deposition take place mainly in the gas phase. 相似文献
63.
T. Engel M. Würtz S. Borneis St. Becker I. Klaft A. Kohl T. Kühl F. Laeri D. Marx K. Meier R. Neumann F. Schmitt P. Seelig L. Völker 《Hyperfine Interactions》1997,108(1-3):251-258
Laser spectroscopy at storage rings often suffers from a limited resolution due to Doppler-broadened resonances. Broadening
is caused by the velocity spread of the ions stored in the beam. In the following, the present status of our work on laser
systems specialized on the specific needs of laser spectroscopy at storage rings is reported.
Two pulsed laser systems were developed. One is a dye laser whose spectral bandwidth can be switched by inserting different
Littrow-prisms into the resonator. An increase in bandwidth up to a factor of 45 was achieved. This laser was used for fast
qualitative scans and high resolution measurements. The other laser system is a Nd : YAG laser pumped optical parametric oscillator.
It is a tunable laser system covering the spectral range from 410 to 4000 nm. Furthermore, a continuous wave laser with a
frequency shifted feedback cavity is described. It shows broadband emission with an adjustable bandwidth of up to 4.5 GHz.
This laser can be advantageous for laser cooling of ion beams.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
64.
65.
Holger Poths Erik Wischerhoff Rudolf Zentel Axel Sch nfeld Guido Henn Friedrich Kremer 《Liquid crystals》1995,18(5):811-818
Two new ferroelectric oligosiloxanes, a cyclic tetramer and a twin, have been synthesized. By a comparative study with their corresponding monomer and side chain polysiloxanes, the influence of oligo- and polymerization on the liquid crystalline and ferroelectric properties have been investigated. Polymerization leads to a stabilization of LC phases through increase of the clearing temperatures and suppression of crystallization. Oligomerization also leads to mesophase broadening, but, due to the low degree of polymerization, the effect is inferior to the linear polysiloxanes. The low viscosity of the oligosiloxanes ensures response times in the microsecond region, thus being comparable with their monomer and conventional LMWFLCs. It is found that polymerization increases the spontaneous polarization Ps. This is attributed to the density increase after polymerization, enhancing the inter-mesogenic interactions. The collective and local dynamics of the OFLCs are influenced differently with respect to their molecular structures. Each oligomer is already a good model for its corresponding polymer concerning the soft mode dynamics. For the local β-relaxation a similar temperature dependence of the relaxation times τ for the cyclic tetramer and for the side chain polysiloxanes is observed. The long axial rotation of the twin, having a very efficient decoupling, is significantly faster, thus resembling the monomer. 相似文献
66.
L. Landström D. Brodoceanu K. Piglmayer D. Bäuerle 《Applied Physics A: Materials Science & Processing》2006,84(4):373-377
Extraordinary optical transmission through metal-coated close-packed monolayers has been observed. The monolayers consist of silica (a-SiO2) or polystyrene microspheres that form two-dimensional close-packed lattices by self-assembly. Metal layers of Ag, Au and Ni with different thicknesses (larger than the skin depth) were evaporated onto such lattices by means of standard techniques. The optical transmission spectra investigated between 300 and 2500 nm show pronounced peaks that scale with the diameter and the optical properties of the composite slabs. The enhanced transmission observed is most likely mediated via plasmons. PACS 78.66.-w; 81.16.Dn; 82.70.Dd 相似文献
67.
S. Trebert Haeberlin F. Lux J. Karl T. Spruss H. Schönenberger 《Journal of Radioanalytical and Nuclear Chemistry》1987,113(2):461-467
As part of an examination of the cytostatic effects of 1,2-diarylethylenediamine-platinum(II)-complexes the contents of platinum and biologically essential trace elements of tumour tissue and different organs were determined. The activation analysis procedure — separation of32P, isolation of199Au and99Mo — is described. In the course of a pharmakokinetical experiment with tumourbearing rats (DMBA induced hormone-dependent tumours) the desired enrichment of the administered drug in the tumour tissue was found. Changes of the trace element level of tumour tissue were found for hormone-dependent MXT-mammary tumours on mice. 相似文献
68.
Vlasov Yu. G. Murzina Yu. G. Legin A. V. Ermolenko Yu. E. Schubert J. Schüoning M. J. Lut H. 《Russian Journal of Applied Chemistry》2002,75(3):351-356
Methods of silicon planar technology and pulsed laser deposition were applied to fabricate fully solid-state chemical sensors for determining ions of copper, lead, cadmium, thallium, and also sulfide and chloride ions on the basis of thin chalcogenide films as ion-sensitive membranes. 相似文献
69.
We derive a moderate deviation principle for the lower tail probabilities of the length of a longest increasing subsequence in a random permutation. It refers to the regime between the lower tail large deviation regime and the central limit regime. The present article together with the upper tail moderate deviation principle in Ref. 12 yields a complete picture for the whole moderate deviation regime. Other than in Ref. 12, we can directly apply estimates by Baik, Deift, and Johansson, who obtained a (non-standard) Central Limit Theorem for the same quantity. 相似文献
70.