全文获取类型
收费全文 | 90633篇 |
免费 | 16362篇 |
国内免费 | 9197篇 |
专业分类
化学 | 61618篇 |
晶体学 | 918篇 |
力学 | 5748篇 |
综合类 | 524篇 |
数学 | 10126篇 |
物理学 | 37258篇 |
出版年
2024年 | 344篇 |
2023年 | 2043篇 |
2022年 | 3293篇 |
2021年 | 3561篇 |
2020年 | 3927篇 |
2019年 | 3510篇 |
2018年 | 3217篇 |
2017年 | 2866篇 |
2016年 | 4585篇 |
2015年 | 4363篇 |
2014年 | 5323篇 |
2013年 | 6768篇 |
2012年 | 8213篇 |
2011年 | 8401篇 |
2010年 | 5550篇 |
2009年 | 5384篇 |
2008年 | 5785篇 |
2007年 | 5071篇 |
2006年 | 4763篇 |
2005年 | 3821篇 |
2004年 | 2943篇 |
2003年 | 2298篇 |
2002年 | 2111篇 |
2001年 | 1816篇 |
2000年 | 1605篇 |
1999年 | 1843篇 |
1998年 | 1593篇 |
1997年 | 1580篇 |
1996年 | 1563篇 |
1995年 | 1322篇 |
1994年 | 1150篇 |
1993年 | 997篇 |
1992年 | 858篇 |
1991年 | 783篇 |
1990年 | 644篇 |
1989年 | 504篇 |
1988年 | 372篇 |
1987年 | 311篇 |
1986年 | 326篇 |
1985年 | 266篇 |
1984年 | 153篇 |
1983年 | 117篇 |
1982年 | 100篇 |
1981年 | 57篇 |
1980年 | 42篇 |
1979年 | 15篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1957年 | 31篇 |
1922年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
In this paper, a generalized anti–maximum principle for the second order differential operator with potentials is proved. As an application, we will give a monotone iterative scheme for periodic solutions of nonlinear second order equations. Such a scheme involves the Lp norms of the growth, 1 ≤ p ≤ ∞, while the usual one is just the case p = ∞. 相似文献
32.
This paper shows that the dimension of internal structure of a component can be measured remotely to a resolution better than 5 μm by use of the combination of high resolution optical microscopy and image processing.A specialised high resolution, long working distance and diffraction limited lens was used to image within the component. A series of digital images were made to map spatially the interior of the component. An edge detector was then used to localise the specific location of features in order that an accurate internal measurement could be made. A visualisation of the internal surface finish was also achieved. 相似文献
33.
Zhao Zheng Zhang Jian-hua Jiang Ya-ling 《International Journal of Theoretical Physics》1997,36(6):1359-1368
The Hawking effect of a nonuniformly rectilinearly accelerating Kinnersley black hole is studied. Its horizons are rotationally
symmetric. Its Hawking temperature depends not only on the time, but also on the polar angle. When a Kinnersley black hole
touches its Rindler horizon, the Hawking temperature at the contact point is reduced to zero. But at the opposite pole of
the black hole, the Hawking temperature increases rapidly. A jet appears as a tail of the accelerating black hole. 相似文献
34.
The thermal and thermo-elastic-plastic response of newly developed ceramic-metalfunctionally graded materials under a thermal shock load is studied.The materials are heated at the ce-ramic surface with a sudden high-intensity heat flux input,and cooled at the metal surface with aflowing liquid nitrogen.Emphasis is placed on two aspects:(1)the influence of the graded composi-tion of the materials on the temperature and stress response;and(2)the optimum design of the gradedcomposition from a unified viewpoint of the heat insulation property and stress relaxation property.Moreover,a comparison between the thermoelastic stress and the thermo-elastic-plastic stress is alsomade to indicate the plasticity effect. 相似文献
35.
L.-Q. Han S.-Y. Zhao Y.-D. Zhou P.-L. Zhang 《Applied physics. B, Lasers and optics》1997,65(3):399-402
Received: 18 June 1996/Revised version: 3 January 1997 相似文献
36.
37.
Lizeng Wang Chengsong Ma Xiaoli Zhang Yibing Ren Yong Yu 《Fresenius' Journal of Analytical Chemistry》1995,351(7):689-691
The electrochemical behavior of the copper-tyrosine complex has been studied by linear-sweep adsorption voltammetry. In 0.02 mol/L Na2HPO4 buffer solution (pH=9.6), the complex can be adsorped on a hanging mercury drop electrode and reduced at a peak potential of about –0.42 V (vs. SCE). The secondary derivative peak height is linear proportional to the concentration of tyrosine in the range 1.0×10–7–5.0×10–5 mol/L. The detection limit is 5×10–8 mol/L.Project supported by the Provincial Science Foundation of Shandong Province 相似文献
38.
39.
40.
采用固源Si分子束外延,在较高的生长温度于Si(100)衬底上制备出Si1-xGex/Si量子阱发光材料。发光样品的质量和特性通过卢瑟福背散射、X射线双晶衍射及光致发光评估。背散射实验中观察到应变超晶格的反常沟道效应;X射线分析表明材料的生长是共度的、无应力释放的,结晶完整性好。低温光致发光主要是外延合金量子阱中带边激子的无声发射和横光学声子参与的激子复合。并讨论了生长温度对量于阱发光的影响。 相似文献