全文获取类型
收费全文 | 10395篇 |
免费 | 659篇 |
国内免费 | 232篇 |
专业分类
化学 | 5391篇 |
晶体学 | 87篇 |
力学 | 367篇 |
综合类 | 25篇 |
数学 | 1290篇 |
物理学 | 2302篇 |
无线电 | 1824篇 |
出版年
2023年 | 117篇 |
2022年 | 228篇 |
2021年 | 270篇 |
2020年 | 291篇 |
2019年 | 279篇 |
2018年 | 264篇 |
2017年 | 223篇 |
2016年 | 365篇 |
2015年 | 358篇 |
2014年 | 398篇 |
2013年 | 663篇 |
2012年 | 699篇 |
2011年 | 770篇 |
2010年 | 477篇 |
2009年 | 425篇 |
2008年 | 594篇 |
2007年 | 499篇 |
2006年 | 478篇 |
2005年 | 404篇 |
2004年 | 304篇 |
2003年 | 299篇 |
2002年 | 263篇 |
2001年 | 209篇 |
2000年 | 181篇 |
1999年 | 153篇 |
1998年 | 107篇 |
1997年 | 101篇 |
1996年 | 110篇 |
1995年 | 77篇 |
1994年 | 127篇 |
1993年 | 92篇 |
1992年 | 100篇 |
1991年 | 91篇 |
1990年 | 77篇 |
1989年 | 66篇 |
1988年 | 63篇 |
1987年 | 48篇 |
1986年 | 54篇 |
1985年 | 74篇 |
1984年 | 72篇 |
1983年 | 51篇 |
1982年 | 67篇 |
1981年 | 57篇 |
1980年 | 63篇 |
1979年 | 55篇 |
1978年 | 60篇 |
1977年 | 51篇 |
1976年 | 46篇 |
1974年 | 39篇 |
1973年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
12.
Julien Villard Houman Borouchaki Dominique Chapelle 《Comptes Rendus Mathematique》2002,335(6):561-566
Numerical simulation methods regarding fabric and cloth draping are generally based on mechanical models. These models are usually applied to uniform grids representing the true geometry of the fabric. Fabrics being a very flexible material, wrinkles appear on its surface when submitted to free or constrained motion. The main problem of the simulation is to represent realistically cloth surface motion. This is strongly dependent on the surface discretization. We present a new cloth animation scheme based on adaptive surface discretization. It can be seen as a multi-grid method which allows us to obtain realistic simulations. We propose also a new mechanical model well suited to our adaptive meshing strategy. A numerical example is given to show the efficiency of the method. To cite this article: J. Villard et al., C. R. Acad. Sci. Paris, Ser. I 335 (2002) 561–566. 相似文献
13.
Le C.T.C. Ishimaru A. Kuga Y. Yea J.-H. 《Geoscience and Remote Sensing, IEEE Transactions on》1998,36(1):61-71
The polarimetric angular memory effect is applied to obtain the average topographic height of a rough surface. This novel effect improves the height sensitivity while maintaining a good degree of correlation between the sensors. By using a reference flat surface, the interferometric phase is linearly related to the mean topographic height. The combination of angular memory and wideband frequency interferometry (AMFI) is realized and offers a means to design a robust interferometric system. Extension of the technique to the pulse scattering problem is studied through the two-frequency mutual coherence function, and its time-domain transform provides an equivalent way to obtain the mean topographic height by combining both spatial and temporal diversity. Millimeter-wave (MMW) experiments are conducted with rough surfaces of different statistics and scattering media of different types (gravel, sand, and rough surfaces) to prove the effectiveness of the technique 相似文献
14.
15.
P Vincent A BrioudeC Journet S RabasteS.T Purcell J Le BrusqJ.C Plenet 《Journal of Non》2002,311(2):130-137
We report here the successful inclusion of carbon nanotubes (CNs) into a TiO2 matrix prepared by a sol-gel method. The presence of CNs in the sol-gel matrix and the structure of the film were analyzed principally by transmission electron microscopy. Complementary information about the behavior of embedded carbon nanotubes versus heat treatment and ion irradiation were obtained by X-ray photoelectron spectroscopy. The elaboration of an inorganic matrix containing embedded carbon nanotubes leads to a new nanocomposite. The possible applications of this nanocomposite are discussed. 相似文献
16.
P. Le Bars 《Journal of Combinatorial Theory, Series A》2006,113(8):1771-1782
The aggregate error locator is defined and a computation method is given. The aggregate error locator is then used in a type of Forney algorithm to compute the error values in the received words of a Ca,b algebraic geometry code. 相似文献
17.
Various image processing applications exploit a model of the human visual system (HVS). One element of HVS-models describes the masking-effect, which is typically parameterized by psycho-visual experiments that employ superimposed sinusoidal stimuli. Those stimuli are oversimplified with respect to real images and can capture only very elementary masking-effects. To overcome these limitations a new psycho-visual test method is proposed. It is based on natural scenery stimuli and operates in the wavelet domain. The collected psycho-visual data is finally used to evaluate the performance of various masking models under conditions as found in real image processing applications like compression. 相似文献
18.
In "Stationary distributions for the random waypoint mobility model" (TMC, Vol. 3, No, 1), Navidi and Camp find the stationary distribution of the random waypoint model, with or without pause on a rectangular area. In this short note, we show that, under the stationary regime, speed and location are independent. 相似文献
19.
We present some algorithms related to rings of Ore polynomials (or, briefly, Ore rings) and describe a computer algebra library
for basic operations in an arbitrary Ore ring. The library can be used as a basis for various algorithms in Ore rings, in
particular, in differential, shift, and q-shift rings.
__________
Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 13, Algebra,
2004. 相似文献
20.
从现有的PCDFs分子的正辛醇 /水分配系数 (logKow)实验数据出发 ,建立定量结构 性质关系方程(QSPR) .采用G98W程序包中的PM3方法对 13 5个多氯代二苯并呋喃 (PCDFs)分子和二苯并呋喃进行了优化计算 ,作业命令为 #pPM3optfreqscf(conver =9) ,以计算所得的分子轨道能量、碳原子电荷作为PCDFs分子结构描述符 ,运用多元线性回归技术建立了PCDFs的logKow与分子结构描述符的四元方程 ,最优相关系数为 0 .95 0 7,标准偏差为 0 .173 7,经检验该模型的稳健性好 ,并对未有实验数据的 85个PCDFs的logKow进行预测 相似文献