全文获取类型
收费全文 | 5888篇 |
免费 | 151篇 |
国内免费 | 56篇 |
专业分类
化学 | 3764篇 |
晶体学 | 78篇 |
力学 | 235篇 |
综合类 | 12篇 |
数学 | 522篇 |
物理学 | 1484篇 |
出版年
2021年 | 36篇 |
2020年 | 45篇 |
2019年 | 48篇 |
2018年 | 51篇 |
2017年 | 37篇 |
2016年 | 90篇 |
2015年 | 103篇 |
2014年 | 83篇 |
2013年 | 285篇 |
2012年 | 229篇 |
2011年 | 262篇 |
2010年 | 154篇 |
2009年 | 133篇 |
2008年 | 231篇 |
2007年 | 242篇 |
2006年 | 258篇 |
2005年 | 233篇 |
2004年 | 198篇 |
2003年 | 172篇 |
2002年 | 192篇 |
2001年 | 138篇 |
2000年 | 139篇 |
1999年 | 94篇 |
1998年 | 84篇 |
1997年 | 126篇 |
1996年 | 126篇 |
1995年 | 97篇 |
1994年 | 114篇 |
1993年 | 136篇 |
1992年 | 121篇 |
1991年 | 75篇 |
1990年 | 69篇 |
1989年 | 97篇 |
1988年 | 85篇 |
1987年 | 80篇 |
1986年 | 78篇 |
1985年 | 93篇 |
1984年 | 103篇 |
1983年 | 78篇 |
1982年 | 79篇 |
1981年 | 79篇 |
1980年 | 73篇 |
1979年 | 72篇 |
1978年 | 69篇 |
1977年 | 69篇 |
1976年 | 57篇 |
1975年 | 79篇 |
1974年 | 72篇 |
1973年 | 59篇 |
1972年 | 31篇 |
排序方式: 共有6095条查询结果,搜索用时 234 毫秒
11.
The gedanken experiment of the clock paradox is solved exactly using the general relativistic equations for a static homogeneous gravitational
field. We demonstrate that the general and special relativistic clock paradox solutions are identical and in particular that
they are identical for finite acceleration. Practical expressions are obtained for proper time and coordinate time by using the destination distance as
the key observable parameter. This solution provides a formal demonstration of the identity between the special and general
relativistic clock paradox with finite acceleration and where proper time is assumed to be the same in both formalisms. By
solving the equations of motion for a freely falling clock in a static homogeneous field elapsed times are calculated for
realistic journeys to the stars.
1 Both authors contributed equally to this paper. 相似文献
12.
Christopher Batchelor-McAuley Craig E Banks Andrew O Simm Timothy G J Jones Richard G Compton 《Chemphyschem》2006,7(5):1081-1085
The benefits of using nanoparticle-modified electrodes are exemplified through the electrochemical detection of protons and/or hydrogen. It is shown that a palladium-nanoparticle-modified boron-doped diamond allows voltammetric information relating to the relative roles played by the surface and the bulk metal to be obtained for the proton-hydrogen system at palladium surfaces which is not accessible using palladium macroelectrodes or microelectrodes. 相似文献
13.
CHEN Zhi-hong XU Li BA Xue-qing ZENG Xian-lu 《高等学校化学研究》2006,22(3):302-307
Introduction Migrationandrecruitmentofleukocytesfromblood toinflammatorylesionsitesaresequentiallyregulated byadhesionmoleculesandtheirreceptors[1].These lectinfamilyplaysamajorroleininitiatingattachement ofneutrophilstotheactivatedendothelium.P selectin,… 相似文献
14.
15.
It is shown that data on the dissociation rate of deuterium obtained in an experiment at the Sudbury Neutrino Observatory provides evidence that the Continuous Spontaneous Localization wavefunction collapse model should have mass–proportional coupling to be viable. 相似文献
16.
Jacques Rouzaud MatthewD. Jones Robert Raja BrianF.G. Johnson John MeurigThomas MelindaJ. Duer 《Helvetica chimica acta》2003,86(5):1753-1759
A set of new, air‐stable, RhI‐based heterogeneous asymmetric hydrogenation catalysts have been synthesised, characterised, and tested. Individual members of this new family all exhibit good enantioselectivity. 相似文献
17.
S. D. Gunapala S. V. Bandara J. K. Liu S. B. Rafol J. M. Mumolo C. A. Shott R. Jones J. Woolaway II J. M. Fastenau A. K. Liu M. Jhabvala K. K. Choi 《Infrared Physics & Technology》2003,44(5-6):411-425
A 9 μm cutoff 640 × 512 pixel hand-held quantum well infrared photodetector (QWIP) camera has been demonstrated with excellent imagery. A noise equivalent differential temperature (NEDT) of 10.6 mK is expected at a 65 K operating temperature with f/2 optics at a 300 K background. This focal plane array has shown background limited performance at a 72 K operating temperature with the same optics and background conditions. In this paper, we discuss the development of this very sensitive long-wavelength infrared camera based on a GaAs/AlGaAs QWIP focal plane array and its performance in quantum efficiency, NEDT, uniformity, and operability. In the second section of this paper, we discuss the first demonstration of a monolithic spatially separated four-band 640 × 512 pixel QWIP focal plane array and its performance. The four spectral bands cover 4–5.5, 8.5–10, 10–12, and 13.5–15 μm spectral regions with 640 × 128 pixels in each band. In the last section, we discuss the array performance of a 640 × 512 pixel broad-band (10–16 μm full-width at half-maximum) QWIP focal plane. 相似文献
18.
19.
Let M be a symplectic manifold with a Hamiltonian circle action with isolated fixed points. We prove that σ (M) = b0(M) − b2(M) + b4(M) − b6(M) + … where σ (M) is the signature of M and bi(M) is the ith Betti number of M. 相似文献
20.
A. K. Shahani N. Korve K. P. Jones D. J. Paynton 《The Journal of the Operational Research Society》1994,45(8):916-926
Asthma is one of the major chronic diseases in many countries. At present there is no cure for asthma, but medical advances can help to reduce the chances of attacks of the condition. Efficient care for asthma involves complexity, uncertainty, variability and the use of scarce resources, and these are the same conditions that indicate a possible use for the modelling approach of operational research. This paper is concerned with a pilot model that was developed through joint work by medical professionals and operational researchers. The development of the model is explained and illustrative results indicate the potential value of the modelling approach for the care of asthma in the community. 相似文献