全文获取类型
收费全文 | 10114篇 |
免费 | 301篇 |
国内免费 | 67篇 |
专业分类
化学 | 6931篇 |
晶体学 | 81篇 |
力学 | 282篇 |
综合类 | 1篇 |
数学 | 1573篇 |
物理学 | 1614篇 |
出版年
2023年 | 49篇 |
2021年 | 103篇 |
2020年 | 191篇 |
2019年 | 141篇 |
2018年 | 98篇 |
2017年 | 108篇 |
2016年 | 211篇 |
2015年 | 190篇 |
2014年 | 238篇 |
2013年 | 465篇 |
2012年 | 534篇 |
2011年 | 650篇 |
2010年 | 336篇 |
2009年 | 284篇 |
2008年 | 573篇 |
2007年 | 524篇 |
2006年 | 505篇 |
2005年 | 504篇 |
2004年 | 495篇 |
2003年 | 340篇 |
2002年 | 366篇 |
2001年 | 123篇 |
2000年 | 106篇 |
1999年 | 89篇 |
1998年 | 96篇 |
1997年 | 135篇 |
1996年 | 150篇 |
1995年 | 89篇 |
1994年 | 71篇 |
1993年 | 106篇 |
1992年 | 81篇 |
1991年 | 87篇 |
1990年 | 88篇 |
1989年 | 79篇 |
1988年 | 87篇 |
1987年 | 85篇 |
1986年 | 74篇 |
1985年 | 137篇 |
1984年 | 151篇 |
1983年 | 109篇 |
1982年 | 134篇 |
1981年 | 125篇 |
1980年 | 99篇 |
1979年 | 106篇 |
1978年 | 134篇 |
1977年 | 121篇 |
1976年 | 115篇 |
1975年 | 83篇 |
1974年 | 84篇 |
1973年 | 80篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
61.
Francis J. Narcowich Joseph D. Ward Holger Wendland. 《Mathematics of Computation》2005,74(250):743-763
In this paper we discuss Sobolev bounds on functions that vanish at scattered points in a bounded, Lipschitz domain that satisfies a uniform interior cone condition. The Sobolev spaces involved may have fractional as well as integer order. We then apply these results to obtain estimates for continuous and discrete least squares surface fits via radial basis functions (RBFs). These estimates include situations in which the target function does not belong to the native space of the RBF.
62.
In this paper a new proof of an identity of Giacomin, Olla, and Spohn is given. The identity relates the 2 point correlation function of a Euclidean field theory to the expectation of the Green's function for a pde with random coefficients. The Euclidean field theory is assumed to have convex potential. An inequality of Brascamp and Lieb therefore implies Gaussian bounds on the Fourier transform of the 2 point correlation function. By an application of results from random pde, the previously mentioned identity implies pointwise Gaussian bounds on the 2 point correlation function. 相似文献
63.
We solve a bitangential interpolation problem for contractive multipliers
on the Arveson space with an arbitrary interpolating set in the closed
unit ball . The solvability criterion is established in terms of positive
kernels. The set of all solutions is parametrized by a Redheffer transform.
Submitted: February 2, 2002. 相似文献
64.
65.
Hubert Grudzński 《Reports on Mathematical Physics》2004,53(3):331-338
New elements of the dual cone of the set of fermion N-representable 2-density operators are proposed. So far, the explicit form of the corresponding necessary conditions for N-representability is obtained for N = 3. In this case the new condition is stronger than the known B- and C-conditions for 3-representability. The results provide evidence that in the spectral decomposition of the N-representable 2-density operator there exists an intrinsic relation between the eigenvalue and the corresponding eigenfunction. 相似文献
66.
Anita M. R. Fisher Kathleen Danenberg Debabrata Banerjee Joseph R. Bertino Peter Danenberg Charles J. Gomer 《Photochemistry and photobiology》1997,66(2):265-270
Loss of p53 function has been correlated with decreased sensitivity to chemotherapy and radiation therapy in a variety of human tumors. Comparable analysis of p53 status with sensitivity to oxidative stress induced by pho-todynamic therapy has not been reported. In the current study we examined photosensitivity in human promye-locytic leukemia HL60 cells exhibiting either wild-type p53, mutated p53 or deleted p53 expression. Experiments were performed using a purpurin, tin ethyl etiopurpurin (SnET2)-, or a porphyrin, Photofrin (PH)-based photo-sensitizer. Total SnET2 accumulation was comparable in all three cell lines. Uptake of PH was highest in cells expressing wild-type p53 but incubation conditions could be adjusted to achieve equivalent cellular PH levels during experiments that analyzed photosensitivity. Survival measurements demonstrated that HL60 cells expressing wild-type p53 were more sensitive to PH- and SnET2-mediated photosensitization, as well as to UVC irradiation, when compared to HL60 cells exhibiting deleted or mutated p53 phenotypes. A rapid apoptotic response was observed following purpurin- and porphyrin-induced photosensitization in all cell lines. Results of this study indicate that photosensitivity is increased in HL60 cells expressing wild-type p53 and that photosensitizer-medi-ated oxidative stress can induce apoptosis through a p53-independent mechanism in HL60 cells . 相似文献
67.
Hubert Schneuwly 《Zeitschrift fur Physik C Particles and Fields》1992,56(Z1):S280-S284
The unexpected and, in conventional terms, yet unexplained experimental results, obtained in systematic measurements of muon
transfer from muonic hydrogen to sulphur and oxygen of sulphur dioxide, seem to violate the principle of reproducibility of
muon transfer data. With the hypothesis of ephemeral muonic hydrogen atoms, the number of different hydrogen atoms can be
reduced from four to two. This hypothesis does, however, not help to interpret the transfer data to helium, neon and argon,
where the muonic hydrogen atoms seem to wear colours. 相似文献
68.
Lionel Joucla Florence Popowycz Olivier Lozach Laurent Meijer Benoît Joseph 《Helvetica chimica acta》2007,90(4):753-763
The syntheses of paullone ( 1a ) and three paullone derivatives, including a sulfur analogue ( 2a ), a tricyclic derivative ( 2b ), and a ring‐enlarged variant ( 2c ), are described, Pd‐catalyzed intramolecular Heck reaction being the key step. The kinase‐inhibitory properties of the novel paullone analogues were investigated. 相似文献
69.
A selective synthesis of ethylene acetal of 4‐bromo‐2‐furancarboxaldehyde ( 4 ) and its pinacolborane derivative ( 5 ) is described. The synthesis was carried out using 2‐furancarboxaldehyde ( 1 ) that was bromi‐nated to 4,5‐dibromo‐2‐furancarboxaldehyde ( 2 ) in an emulsion of aluminum chloride and methylene chloride. The product was isolated, protected as ethylene acetal, and selectively debrominated to the ethylene acetal of 4‐bromo‐2‐furancarboxaldehyde ( 4 ) in one step. This moiety was reacted with pinacolborane to give a reactive reagent of Suzuki coupling. 相似文献
70.
R. A. Taylor S. Haacke B. Deveaud I. Bar Joseph R. Zimmermann 《Physica E: Low-dimensional Systems and Nanostructures》1998,2(1-4)
The time-resolved secondary emission of resonantly created excitons in GaAs quantum wells is studied using femtosecond up-conversion spectroscopy. The behaviour of the rise and decay of the secondary emission and reflectivity in quantum wells is strongly dependent upon the disorder at the interfaces, the exciton density and the temperature. In the case of low densities and temperatures the emission is independent of the exciton density and rises quadratically in time, in excellent agreement with recent theory for Rayleigh scattering from two-dimensional excitons subjected to disorder. These rise times are compared directly with
times measured by time-integrated four-wave mixing (FWM). The comparison of the dynamics displayed in time-resolved secondary radiation and time-integrated FWM provide a clear understanding of the coherence properties of QW excitons in the first few picoseconds after excitation. High-contrast oscillations that are due to quantum beats between the heavy- and light-hole 1s-states are seen. The visibility decay at very low densities is long
ps and is related to the action of potential fluctuations on the scattering of heavy-hole and light-hole excitons. 相似文献