全文获取类型
收费全文 | 1011篇 |
免费 | 34篇 |
国内免费 | 5篇 |
专业分类
化学 | 628篇 |
晶体学 | 14篇 |
力学 | 28篇 |
数学 | 105篇 |
物理学 | 275篇 |
出版年
2023年 | 9篇 |
2022年 | 19篇 |
2021年 | 21篇 |
2020年 | 16篇 |
2019年 | 26篇 |
2018年 | 17篇 |
2017年 | 19篇 |
2016年 | 30篇 |
2015年 | 20篇 |
2014年 | 38篇 |
2013年 | 52篇 |
2012年 | 55篇 |
2011年 | 62篇 |
2010年 | 41篇 |
2009年 | 34篇 |
2008年 | 70篇 |
2007年 | 69篇 |
2006年 | 48篇 |
2005年 | 48篇 |
2004年 | 25篇 |
2003年 | 26篇 |
2002年 | 25篇 |
2001年 | 22篇 |
2000年 | 14篇 |
1999年 | 17篇 |
1998年 | 11篇 |
1997年 | 7篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 20篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 16篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1977年 | 4篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1972年 | 5篇 |
排序方式: 共有1050条查询结果,搜索用时 93 毫秒
981.
982.
A new theory for incorporating short range order (SRO) in the cluster Bethe lattice method (CBLM) for disordered binary alloys is proposed. It is applied to determine the condition for the appearance of moments in the disordered phase of a narrow-band metal for general values of concentration and SRO parameter. The final result (i) yields all the known limiting conditions exactly and (ii) displays in a transparant form the SRO dependence, indicating the merit of the present approach. 相似文献
983.
Zhao Chun-Liu Lu Chao Yan Min Wang Xiaoyan Lou Junjun Li Qin Zhou Xiaoqun Cai Qing P.R.Chaudhuri 《光学学报》2003,23(Z1)
We demonstrate a highly birefringent photonic crystal fiber by utilizing the asymmetric core design. Based on spectral measurements of the polarization mode interfering, we estimate that the fiber has a beat length of about 0.33 mm at 1545 nm. 相似文献
984.
B. C. Giri A. Goswami K. S. Chaudhuri 《The Journal of the Operational Research Society》1996,47(11):1398-1405
A generalized EOQ model for deteriorating items is considered here in which the demand rate, deterioration rate, holding cost and ordering cost are all assumed to be continuous functions of time. Shortages are also allowed and are completely backlogged. The planning horizon is finite and the replenishment periods are assumed to be constant. The optimal replenishment policy and the decision rule which minimizes the total system cost are derived. A numerical example is given to illustrate the developed model. Sensitivity analysis is also presented for the given model. 相似文献
985.
A novel iridoid glucoside, named globularidin, lacking the typical double bond between C(3) and C(4), has been isolated from the whole plant of Globularia alypum by the combination of open column- and high-performance liquid chromatography. The structure of this compound was established by chemical transformation and spectral data. 相似文献
986.
Pink-brown crystalline alkali-metal trifluoromonosulphatomanganates(III), A2[MnF3(SO4)] (A = NH4, Li, Na or K), have been synthesised in high yields by reacting KMnO4 or MnO(OH) with 40% HF and A2SO4 or by the reaction of MnO(OH) with 40% HF and A2S2O8 (A = NH4 or K). The chemicallly estimated oxidation state of manganese occurs between 2.9 and 3.1, and the room temperature magnetic moments lie in the range 4.0–4.2 BM. (NH4)2[MnF3(SO4)] on being pyrolysed at 340°C yields MnSO4. 相似文献
987.
988.
Wu JJ Yarwood DR Sills MA Chaudhuri B Muller L Zurini M Sills MA 《Combinatorial chemistry & high throughput screening》2000,3(1):27-36
Cyclin-dependent kinases such as Cdk4 are involved in the control of cell cycle progression, and misregulation of Cdk4 has been implicated in many types of cancers. In the present study, we report the development of a novel homogeneous assay using an affinity peptide-tagging technology for rapidly discovering Cdk4 inhibitors. The DNA sequence encoding a streptavidin recognition motif, or StrepTag (AWRHPQFGG), was cloned and expressed at the C-terminus of a fusion protein of a 152-amino acid hyperphosphorylation domain (Rb152) of the retinoblastoma protein (Rb) linked to GST at the N-terminus. This affinity peptide-tagged protein (GST-Rb152-StrepTag), which contains the two known phosphorylation sites of Rb, specifically phosphorylated by Cdk4 in vivo, was used as a substrate in the current in vitro kinase assay. After phosphorylation, scintillation proximity assay (SPA) scintillant beads coated with streptavidin were added. Radiolabeled GST-Rb152-StrepTag was brought in close proximity to the SPA scintillant beads through the interaction between StrepTag and streptavidin, resulting in the emission of light from beads. By applying the affinity peptide-tagging technology, we have eliminated the separation and wash steps which are normally required in a radioactive filtration assay. Therefore, this homogeneous method is simple, robust, and highly amenable to high-throughput screening of Cdk4-specific inhibitors. Furthermore, the affinity peptide tagging technique reported here is a simple, generic method that can be applied to many recombinant proteins for the development of kinase and protein-protein interaction assays. 相似文献
989.
The quantum transport properties of a non-interacting mesoscopic ring sandwiched between two metallic electrodes are investigated by the use of Green's function technique. Here, we introduce parametric approach, based on the tight-binding model to study these transport properties. The electronic transport properties are focused in three aspects: (a) geometry of the mesoscopic ring, (b) coupling strength of the ring with the two electrodes and (c) magnetic flux threaded by the ring. 相似文献
990.
In this paper we study weaknesses of two variants of RSA: Dual RSA and Common Prime RSA. Several schemes under the framework of Dual RSA have been proposed by Sun et al. (IEEE Trans Inf Theory 53(8):2922–2933, 2007). We here concentrate on the Dual CRT-RSA scheme and present certain range of parameters where it is insecure. As a corollary of our work, we prove that the Dual Generalized Rebalanced-RSA (Scheme III of Sun et al.) can be efficiently broken for a significant region where the scheme has been claimed to be secure. Next we consider the Common Prime RSA as proposed by Wiener (IEEE Trans. Inf. Theory 36:553–558, 1990). We present new range of parameters in Common Prime RSA where it is not secure. We use lattice based techniques for the attacks. 相似文献