全文获取类型
收费全文 | 11093篇 |
免费 | 1013篇 |
国内免费 | 744篇 |
专业分类
化学 | 1603篇 |
晶体学 | 30篇 |
力学 | 923篇 |
综合类 | 133篇 |
数学 | 8318篇 |
物理学 | 1843篇 |
出版年
2024年 | 23篇 |
2023年 | 101篇 |
2022年 | 140篇 |
2021年 | 184篇 |
2020年 | 300篇 |
2019年 | 311篇 |
2018年 | 282篇 |
2017年 | 296篇 |
2016年 | 355篇 |
2015年 | 275篇 |
2014年 | 505篇 |
2013年 | 1009篇 |
2012年 | 544篇 |
2011年 | 594篇 |
2010年 | 512篇 |
2009年 | 675篇 |
2008年 | 643篇 |
2007年 | 717篇 |
2006年 | 630篇 |
2005年 | 540篇 |
2004年 | 500篇 |
2003年 | 468篇 |
2002年 | 455篇 |
2001年 | 358篇 |
2000年 | 372篇 |
1999年 | 342篇 |
1998年 | 274篇 |
1997年 | 278篇 |
1996年 | 177篇 |
1995年 | 127篇 |
1994年 | 118篇 |
1993年 | 66篇 |
1992年 | 93篇 |
1991年 | 50篇 |
1990年 | 51篇 |
1989年 | 39篇 |
1988年 | 29篇 |
1987年 | 27篇 |
1986年 | 32篇 |
1985年 | 47篇 |
1984年 | 54篇 |
1983年 | 25篇 |
1982年 | 40篇 |
1981年 | 39篇 |
1980年 | 38篇 |
1979年 | 36篇 |
1978年 | 18篇 |
1977年 | 24篇 |
1976年 | 23篇 |
1974年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Nicolas Bouleau 《Journal of Functional Analysis》2007,251(1):325-345
The error on a real quantity Y due to the graduation of the measuring instrument may be asymptotically represented, when the graduation is regular and fines down, by a Dirichlet form on R whose square field operator does not depend on the probability law of Y as soon as this law possesses a continuous density. This feature is related to the “arbitrary functions principle” (Poincaré, Hopf). We give extensions of this property to Rd and to the Wiener space for some approximations of the Brownian motion. This gives new approximations of the Ornstein-Uhlenbeck gradient. These results apply to the discretization of some stochastic differential equations encountered in mechanics. 相似文献
92.
采用旋转锥镜相机,进行激光散斑剪切照相,研测缓慢变形物体的动态曲率和斜率。拍摄一张散斑图即可获得曲率和斜率动态变化的全过程。 相似文献
93.
For an impulsive delay differential equation exponent estimates of solutions have been obtained. 相似文献
94.
A trajectory-following method for unconstrained optimization 总被引:2,自引:0,他引:2
A trajectory-following method with interesting properties is considered for solving unconstrained nonlinear programming problems. The trajectory is defined by a special system of ordinary differential equations. This system uses only the gradient of the objective function. Numerical examples are given.The work of the second author was supported by the DFG Schwerpunkt Anwendungs-bezogene Optimierung and Steuerung. 相似文献
95.
We compute the cyclic homology of the coordinate ring A(SLq(2)) of the quantum algebraic group SL
q
(2). We observe a degeneration of the noncommutative de Rham complex. The results are also verified from the point of view of Connes' noncommutative differential geometry. 相似文献
96.
A recursive method is developed for the solution of coupled algebraic Riccati equations and corresponding linear Nash strategies of weakly interconnected systems. It is shown that the given algorithm converges to the exact solution with the rate of convergence ofO(2), where is a small coupling parameter. In addition, only low-order systems are involved in algebrdic computations; the amount of computations required does not grow per iteration and no analyticity assumption is imposed on the system coefficients.This work was supported by Rutgers University Research Council under Grant No. 2-02188. 相似文献
97.
A. Bigi P. P. Castellani G. Cojazzi N. Roveri 《Journal of Thermal Analysis and Calorimetry》1992,38(3):505-514
A differential scanning calorimetric, thermogravimetric and electron microscopic investigation has been carried out on the uncalcified areas of turkey leg flexor tendon as a function of age. Rehydrated samples exhibit an increase of thermal stability with age. The HD values drop from about 11 cal·g–1 in the first weeks of life down to 7 cal·g–1 after the 11th week.At about 11 weeks, the collagen fibril diameter distribution passes from unimodal to multimodal. The DSC curves as well as the TG-DTG curves recorded from dried samples do not show any appreciable difference with ageing. The variations in thermal behaviour of rehydrated samples and fibril diameter distribution could be related to modifications in water binding with ageing.The Authors are grateful to Dr. G. Fabris for discussion and help in the selection of the samples. They also wish to thank Mr. G. Pizzuto for excellent technical assistance. The financial support by Consiglio Nazionale delle Ricerche is gratefully acknowledged. 相似文献
98.
李和 《广东微量元素科学》2002,9(3):66-68
为研制司帕沙星软膏,建立其含量测定方法。用差示紫外分光光度法在306nm外测定司帕沙星的含量。平均回收率为99.98%,RSD为0.72%,线性范围15.62-40.14μg/ml。该法简便、准确、快捷。 相似文献
99.
100.
Mura P. Maestrelli F. Cirri M. Furlanetto S. Pinzauti S. 《Journal of Thermal Analysis and Calorimetry》2003,73(2):635-646
The interactions of trimethoprim, sulphadiazine and sulphamethoxazole with natural (a- b-, g- ) and amorphous (RAMEB) or crystalline
(DIMEB) methylated b-cyclodextrins were investigated both in aqueous solution (using phase-solubility analysis) and in the
solid state (using DSC supported by X-ray analysis). In particular, DSC studies enabled determination of the relative degree
of crystallinity of each drug in its physical and ground mixtures with the different cyclodextrins on the basis of the variation
of its heat of fusion in comparison with that of the pure drug. In all cases, the host cavity size was a prevalent factor
for the inclusion complexation in liquid state. On the contrary, it had a negligible effect on solid-state interactions in
terms of drug amorphization. DIMEB and RAMEB exhibited similar performances in aqueous solution, showing that the presence
of methyl-groups improved the complexing and solubilizing properties of b-cyclodextrin. However, DSC studies revealed that
RAMEB was clearly more active in performing solid-state interactions, i.e. drug amorphization, and as stabilizing agent for
the amorphous state brought forth.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献