全文获取类型
收费全文 | 273223篇 |
免费 | 2313篇 |
国内免费 | 738篇 |
专业分类
化学 | 127269篇 |
晶体学 | 3991篇 |
力学 | 14543篇 |
综合类 | 7篇 |
数学 | 42172篇 |
物理学 | 88292篇 |
出版年
2021年 | 991篇 |
2020年 | 1112篇 |
2019年 | 1127篇 |
2018年 | 10440篇 |
2017年 | 11407篇 |
2016年 | 6533篇 |
2015年 | 2844篇 |
2014年 | 2609篇 |
2013年 | 7821篇 |
2012年 | 10749篇 |
2011年 | 20841篇 |
2010年 | 12437篇 |
2009年 | 12586篇 |
2008年 | 18258篇 |
2007年 | 21895篇 |
2006年 | 7208篇 |
2005年 | 13883篇 |
2004年 | 9558篇 |
2003年 | 8563篇 |
2002年 | 6394篇 |
2001年 | 6188篇 |
2000年 | 4866篇 |
1999年 | 3515篇 |
1998年 | 2671篇 |
1997年 | 2632篇 |
1996年 | 2743篇 |
1995年 | 2370篇 |
1994年 | 2249篇 |
1993年 | 2110篇 |
1992年 | 2410篇 |
1991年 | 2379篇 |
1990年 | 2093篇 |
1989年 | 2076篇 |
1988年 | 2108篇 |
1987年 | 2040篇 |
1986年 | 1945篇 |
1985年 | 2860篇 |
1984年 | 2850篇 |
1983年 | 2298篇 |
1982年 | 2473篇 |
1981年 | 2357篇 |
1980年 | 2313篇 |
1979年 | 2278篇 |
1978年 | 2355篇 |
1977年 | 2229篇 |
1976年 | 2197篇 |
1975年 | 2168篇 |
1974年 | 2068篇 |
1973年 | 2190篇 |
1972年 | 1232篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
H. Caines 《The European Physical Journal C - Particles and Fields》2007,49(1):297-301
The soft physics, pT<2 GeV/c, observables at both RHIC and the SPS have now been mapped out in quite specific detail. From these results there
is mounting evidence that this regime is primarily driven by the multiplicity per unit rapidity, dNch/dη. This suggests that the entropy of the system alone is the underlying driving force for many of the global observables
measured in heavy-ion collisions. That this is the case and there is an apparent independence on collision energy is surprising.
I present the evidence for this multiplicity scaling and use it to make some extremely naive predictions for the soft sector
results at the LHC. 相似文献
992.
993.
Emrys A. Jones Nicholas P. Lockyer John C. Vickerman 《International journal of mass spectrometry》2007,260(2-3):146
Recent developments in desorption/ionisation mass spectrometry techniques have made their application to biological analysis a realistic and successful proposition. Developments in primary ion source technology, mainly through the advent of polyatomic ion beams, have meant that the technique of secondary ion mass spectrometry (SIMS) can now access the depths of information required to allow biological imaging to be a viable option.Here the role of the primary ion C60+ is assessed with regard to molecular imaging of lipids and pharmaceuticals within tissue sections. High secondary ion yields and low surface damage accumulation are demonstrated on both model and real biological samples, indicating the high secondary ion efficiency afforded to the analyst by this primary ion when compared to other cluster ion beams used in imaging. The newly developed 40 keV C60+ ion source allows the beam to be focused such that high resolution imaging is demonstrated on a tissue sample, and the greater yields allow the molecular signal from the drug raclopride to be imaged within tissue section following in vivo dosing.The localisation shown for this drug alludes to issues regarding the chemical environment affecting the ionisation probability of the molecule; the importance of this effect is demonstrated with model systems and the possibility of using laser post-ionisation as a method for reducing this consequence of bio-sample complexity is demonstrated and discussed. 相似文献
994.
V. G. Maiorov A. I. Nikolaev B. Ya. Zil’berman V. M. Shcherbakov 《Russian Journal of Applied Chemistry》2007,80(6):874-878
A scheme for utilization of chloride solutions of complex composition with α-and β-activity of up to 35 and 28 kBq 1?1, respectively, is suggested. 相似文献
995.
996.
A new mechanism of pulsed laser oscillation based on ion-ion recombination is proposed. The advantages of utilizing this mechanism in a pulsed mode are considered, and the expected characteristics of the proposed lasers are estimated. 相似文献
997.
998.
A Network Simulation of High-congestion Road-traffic Flows in Cities with Marine Container Terminals
James A. Pope Terry R. Rakes Loren Paul Rees Ingrid W. M. Crouch 《The Journal of the Operational Research Society》1995,46(9):1090-1101
Port cities where marine cargo terminals are located are generally near urban areas characterized by high-congestion road traffic. Changes in cargo traffic volumes into a marine terminal, or in the surrounding traffic arteries, which carry this traffic, can significantly affect the terminal's operations. Conversely, activity at the terminal can have an impact on the traffic levels and congestion for a considerable distance from the terminal. This paper demonstrates a methodology useful for studying the impact of road traffic flows on marine container terminals located in highly congested areas. This model was developed at the request of the Virginia Center for World Trade and was used to answer three planning questions in the port of Hampton Roads, Virginia, USA-what would be the impact of: opening a new section of interstate highway, a projected doubling of container traffic at one terminal, and a daily unit train in the vicinity of another terminal. The problem was made more challenging by limited data-collection funds. None the less, the model was deemed valid by a panel of traffic experts and officials from several major state and private agencies involved in marine traffic management. The model results were subsequently a factor in two major decisions related to terminal management. 相似文献
999.
I. N. Belousov A. A. Makhnev 《Proceedings of the Steklov Institute of Mathematics》2007,257(1):S47-S60
Possible orders and subgraphs of the fixed points of a distance-regular graph with the intersection array {8, 7, 5; 1, 1, 4} are found. It is shown that such a graph is not vertex-transitive. 相似文献
1000.
A. V. Potepun 《Journal of Mathematical Sciences》2007,141(5):1545-1556
In part I of the paper, we have defined n-dimensional C0-manifolds in ℝn(m ≥ n) with locally-finite n-dimensional variations (a generalization of locally-rectifiable curves to dimensionn > 1) and
integration of measurable differential n-forms over such manifolds. The main result of part II states that an n-dimensional
manifold that is C1-embedded into ℝm has locally-finite variations and the integral of a measurable differential n-form defined in part I can be calculated by
the well-known formula. Bibliography: 5 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 333, 2006, pp. 66–85. 相似文献