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991.
Youxin Yao Wenju Zeng Bin Zhang Yunqi Liu Daoben Zhu 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(3):e90-e91
The title complex, C14H20O4S8+.BF4?, is a charge‐transfer complex with typical charges for the donor and anion of +1 and ?1, respectively. Two centrosymmetrically related donors form a face‐to‐face π‐dimer with a strong intermolecular S?S interaction. These π‐dimers stack along the a axis to form a donor column. The structure is extensively hydrogen bonded. 相似文献
992.
Huanrong Li Yingming Yao Qi Shen Linhong Weng 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):747-748
The title complex, [Y2(C6H7)4(C3H7O)2], is a centrosymmetric dimer bridged through the O atoms of the isopropoxide ligands. The Y2O2 unit is planar and the geometry around the eight‐coordinate Y atom is distorted pseudo‐tetrahedral. The Y—O distances are 2.2228 (19) and 2.2432 (19) Å, and the O—Y—O angle is 74.86 (7)°. 相似文献
993.
A novel ion-selective sensor for procaine hydrochloride has been proposed and applied successfully to analysis of pharmaceutical
preparations. The sensor is based on modification of the Ag-electrode of an AT-cut piezoelectric quartz crystal with a PVC
membrane containing procaine tetraphenylborate. A linear relation between the logarithm of the response frequency and the
logarithm of the procaine hydrochloride concentration was found experimentally and could be explained by combination of a
modified Sauerbrey equation and the Freundlich isotherm. The detection range was from 8.3 × 10−8 to 5.0 × 10−3 M with a detection limit of 8.3 × 10−8 M. The selectivity of the sensor and the influence of experimental parameters such as solution pH and detection time were
investigated.
Received February 10, 1999. Revision October 10, 1999. 相似文献
994.
A new type of two-dimensional network was found in the hydrogen-bonded molecular assemblies of copper(II) α,β-unsaturated
carboxylate complexes with TMP [OP(OMe)3], {Cu2A4(H2O)2[OP(OMe)3]}
n
[(1) A = CH2=CHCO2
−; (2) A = CH2=C(Me)CO2
−]. The crystal structure of (1) has been determined by single-crystal X-ray diffraction. Both complexes are unique in terms of a sheet structure brought
about by O—H ⋯ O hydrogen-bonded interactions both between neighbouring Cu2A4(H2O)2 units and between Cu2A4(H2O)2 and OP(OMe)3 molecules. The electronic reflectance spectra in the solid state suggest a square pyramidal coordination environment around
the copper(II) atom. Room temperature X-band e.s.r. spectra of powered samples and variable-temperature magnetic susceptibility
studies indicate the presence of strong antiferromagnetic exchange interactions between two copper(II) atoms, with 2J = −310 cm−1 for (1) and 2J = −304 cm−1 for (2) respectively.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
995.
Zhang Lei Xu Chao Guo Yaohao Zhu Guangpu Cai Shiyu Wang Xin Jing Wenlong Sun Hai Yang Yongfei Yao Jun 《Transport in Porous Media》2021,140(3):713-725
Transport in Porous Media - Pore scale immiscible displacement is crucial in oil industry. The surface roughness of throat is an important factor affecting water–oil interface movement. In... 相似文献
996.
Zhao Xiaopeng Köbis Markus A. Yao Yonghong Yao Jen-Chih 《Journal of Optimization Theory and Applications》2021,190(1):82-107
In this paper, we propose a projected subgradient method for solving constrained nondifferentiable quasiconvex multiobjective optimization problems. The algorithm is based on the Plastria subdifferential to overcome potential shortcomings known from algorithms based on the classical gradient. Under suitable, yet rather general assumptions, we establish the convergence of the full sequence generated by the algorithm to a Pareto efficient solution of the problem. Numerical results are presented to illustrate our findings.
相似文献997.
半导体纳米晶体(NCs)具有良好的光稳定性,广泛的发射持久性和高消光系数,在过去几年被广泛研究报道,其中,硒化镉半导体纳米晶体(CdSe NCs)被广泛用于电子照明、太阳能发电、光电传感等领域。然而CdSe NCs的电学、热力学和光物理性质具有较强的尺寸依赖性,在传统的制备方法及应用中容易出现晶体表面缺陷和悬空键以及较为严重的生物毒性和环境毒性。为了实现量子点在各个领域的应用,必须严格控制CdSe NCs的发光波长,尺寸分布以及荧光性能。本研究通过高温热注射法合成了单分散的胶体发光CdSe NCs,使用表面配体对CdSe NCs进行修饰,研究了不同烷基链长度的配体对CdSe NCs尺寸分布和荧光性能的影响,并通过改变溶剂配比制备了纺丝溶液,将其与聚乙烯吡咯烷酮(PVP)进行杂化,制备了PVP/CdSe QDs荧光杂化纤维。结果表明,与传统CdSe NCs相比,经表面配体的修饰的CdSe NCs在有机溶液中因分子间吸附的降低在溶液中有良好的稳定性,具有可调节的溶解度,弥补了缺陷和悬空键造成的荧光性能下降。在CdSe晶体结构的形成过程中,表面配体也有着显著的调控作用。并且更为重要的是,该研究将表面配体修饰与杂化相结合,改善了表面配体的附着,在杂化材料的制备过程中避免了硒化镉纳米晶体与高分子基体直接接触,为荧光团提供了良好的发光微环境,保证了CdSe NCs的荧光性能,使杂化纤维具有良好而稳定的荧光性能。同时,PVP的引入使CdSe NCs的生物毒性和环境毒性得以改善,使材料更加环境友好且具有更好的生物相容性,大大提升了材料的应用范围。事实证明,PVP/CdSe QDs杂化微纤维杂化相容性和分散性良好,具有优异的荧光性能和材料成型性,纤维合成方式简便易行且造价低廉,可应用于溶液处理,光学照明,电极材料,和生物成像等各个领域。 相似文献
998.
With graphs considered as natural models for many network design problems, edge connectivity κ′(G) and maximum number of edge-disjoint spanning trees τ(G) of a graph G have been used as measures for reliability and strength in communication networks modeled as graph G (see Cunningham, in J ACM 32:549–561, 1985; Matula, in Proceedings of 28th Symposium Foundations of Computer Science, pp 249–251, 1987, among others). Mader (Math Ann 191:21–28, 1971) and Matula (J Appl Math 22:459–480, 1972) introduced the maximum subgraph edge connectivity \({\overline{\kappa'}(G) = {\rm max} \{\kappa'(H) : H {\rm is} \, {\rm a} \, {\rm subgraph} \, {\rm of} G \}}\) . Motivated by their applications in network design and by the established inequalities $$\overline{\kappa'}(G) \ge \kappa'(G) \ge \tau(G),$$ we present the following in this paper:
- For each integer k > 0, a characterization for graphs G with the property that \({\overline{\kappa'}(G) \le k}\) but for any edge e not in G, \({\overline{\kappa'}(G + e) \ge k+1}\) .
- For any integer n > 0, a characterization for graphs G with |V(G)| = n such that κ′(G) = τ(G) with |E(G)| minimized.
999.
1000.
姚裕丰 《纯粹数学与应用数学》2014,(1):1-6
通过计算及归纳的方法,得到了n×n矩阵代数中极大线性无关的反交换2-幂零矩阵的个数,推广了相关文献中的一般线性李代数gl(n)的交换子代数的最大维数这一结论. 相似文献