全文获取类型
收费全文 | 4918篇 |
免费 | 415篇 |
国内免费 | 1010篇 |
专业分类
化学 | 3289篇 |
晶体学 | 24篇 |
力学 | 247篇 |
综合类 | 240篇 |
数学 | 1418篇 |
物理学 | 1125篇 |
出版年
2024年 | 6篇 |
2023年 | 92篇 |
2022年 | 126篇 |
2021年 | 149篇 |
2020年 | 162篇 |
2019年 | 117篇 |
2018年 | 94篇 |
2017年 | 105篇 |
2016年 | 123篇 |
2015年 | 165篇 |
2014年 | 249篇 |
2013年 | 286篇 |
2012年 | 371篇 |
2011年 | 348篇 |
2010年 | 326篇 |
2009年 | 295篇 |
2008年 | 315篇 |
2007年 | 416篇 |
2006年 | 431篇 |
2005年 | 298篇 |
2004年 | 232篇 |
2003年 | 176篇 |
2002年 | 132篇 |
2001年 | 143篇 |
2000年 | 191篇 |
1999年 | 153篇 |
1998年 | 138篇 |
1997年 | 104篇 |
1996年 | 81篇 |
1995年 | 81篇 |
1994年 | 54篇 |
1993年 | 65篇 |
1992年 | 70篇 |
1991年 | 47篇 |
1990年 | 30篇 |
1989年 | 9篇 |
1988年 | 40篇 |
1987年 | 43篇 |
1986年 | 46篇 |
1985年 | 10篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1981年 | 6篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1971年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有6343条查询结果,搜索用时 15 毫秒
1.
This paper is concerned with the Cauchy problem on the Boltzmann equation without angular cutoff assumption for hard potential in the whole space. When the initial data is a small perturbation of a global Maxwellian, the global existence of solution to this problem is proved in unweighted Sobolev spaces with . But if we want to obtain the optimal temporal decay estimates, we need to add the velocity weight function, in this case the global existence and the optimal temporal decay estimate of the Boltzmann equation are all established. Meanwhile, we further gain a more accurate energy estimate, which can guarantee the validity of the assumption in Chen et al. (0000). 相似文献
2.
3.
4.
《中国化学快报》2022,33(8):3772-3776
RNA molecules contain diverse modifications that display important functions in a variety of physiological and pathological processes. So far over 150 chemical modifications have been characterized to be present in various RNA species, such as in messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA). Previous studies revealed that certain RNA modifications were correlated to specific human diseases, indicating RNA modifications could serve as the potential indicator of human diseases. However, systemic investigation of the alteration of RNA modifications in different RNA species of carcinoma tissues are still lacked. Herein, we carried out the comprehensive profiling and evaluation of the alteration of RNA modifications in thyroid carcinoma by liquid chromatography-tandem mass spectrometry (LC-ESI-MS/MS) analysis. The developed method allowed us to simultaneously detect 48 different types of RNA modifications. Using this method, we detected 10, 15, 14, and 25 modifications in mRNA, 18S rRNA, 28S rRNA and small RNA (< 200 nt), respectively. Compared to the normal tissues, we revealed a total of 14 RNA modification exhibited significant increase and 2 RNA modifications showed significant decrease in thyroid carcinoma tissues. Our study provided the first comprehensive profile as well as the alteration of modifications in different RNA species in thyroid carcinoma and matched tumor-adjacent normal tissues. The altered pattern RNA modifications may serve as the indicator of thyroid carcinoma. Moreover, this study may promote the in-depth understanding of the regulatory roles of RNA modifications in thyroid carcinoma. 相似文献
5.
Chen Fenge Li Bing Peng Xingchun 《Methodology and Computing in Applied Probability》2022,24(2):635-659
Methodology and Computing in Applied Probability - This paper is devoted to the study of an optimal investment and risk control problem for an insurer. The risky asset process and the insurance... 相似文献
6.
7.
Alessandro Morando Paola Trebeschi Tao Wang 《Journal of Differential Equations》2019,266(9):5397-5430
We show the short-time existence and nonlinear stability of vortex sheets for the nonisentropic compressible Euler equations in two spatial dimensions, based on the weakly linear stability result of Morando and Trebeschi (2008) [20]. The missing normal derivatives are compensated through the equations of the linearized vorticity and entropy when deriving higher-order energy estimates. The proof of the resolution for this nonlinear problem follows from certain a priori tame estimates on the effective linear problem in the usual Sobolev spaces and a suitable Nash–Moser iteration scheme. 相似文献
8.
9.
ON A PAIR OF NON-ISOMETRIC ISOSPECTRAL DOMAINS WITH FRACTAL BOUNDARIES AND THE WEYL-BERRY CONJECTURE
ONAPAIROFNONISOMETRICISOSPECTRALDOMAINSWITHFRACTALBOUNDARIESANDTHEWEYLBERRYCONJECTURESLEEMAN,B.D.CHENHUAManuscriptrec... 相似文献
10.
Let V be a hypersurface with an isolated singularity at the origin in ? n+1. It is a natural question to ask when V is defined by weighted homogeneous polynomial or homogeneous polynomial up to biholomorphic change of coordinates. In 1971, a beautiful theorem of Saito gives a necessary and sufficient condition for V to be defined by a weighted homogeneous polynomial. For a two-dimensional isolated hypersurface signularity V, Xu and Yau found a coordinate free characterization for V to be defined by a homogeneous polynomial. Recently Lin and Yau gave necessary and sufficient conditions for a 3-dimensional isolated hypersurface singularity with geometric genus bigger than zero to be defined by a homogeneous polynomial. The purpose of this paper is to prove that Lin-Yau’s theorem remains true for singularities with geometric genus equal to zero. 相似文献