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991.
992.
采用光抽运有机激光增益材料产生的放大自发辐射(amplified spontaneous emission ASE), 实现了不同浓度液体的实时检测. 以两种聚合物poly(9, 9-dioctylfluorene-co-benzothiadiazole)和poly(3-hexylthiophene)共混的激光增益介质薄膜作为平面光波导, 观察在滴加少量溶液前后以及不同溶液浓度下, 由于光波导的相对折射率变化导致的放大自发辐射阈值及峰位的变化, 实现对溶液检测. 实验结果显示, 在常温常压下对25 wt.% NaCl溶液检测可得与纯水相比, 放大自发辐射光谱红移了4.5 nm, ASE阈值从0.579 μJ/pulse上升到1.447 μJ/pulse, 约2.5倍, 溶液检测灵敏度达到97.8 nm/RIU(refractive index unit), 精度达到141.9 nm/RIU, 充分说明上述方法能实现高灵敏度溶液检测. 相似文献
993.
复合材料在制造、使用和维修过程中不可避免的受外来意外物体的低速冲击,造成结构的损伤。材料本身存在各向异性、纤维铺层方向误差等复杂结构特性,导致延迟-累加损伤成像方法难以实现冲击损伤的准确检测。针对这一问题,本文采用了一种与信号传播速度无关的损伤概率成像方法,该方法利用能量损伤因子,将各路径周围的像素点以椭圆分布的形式对损伤进行概率化表述,然后对各路径损伤因子进行合成成像,实现了复合材料冲击损伤的准确监测。实验结果表明,利用能量损伤因子可以监测复合材料冲击损伤,利用损伤概率成像方法可以实现冲击损伤位置的判别。 相似文献
994.
995.
Let G be an unicycle graph and d
v
the degree of the vertex v. In this paper, we investigate the following topological indices for an unicycle graph ,
, where m ≥ 2 is an integer. All unicycle graphs with the largest values of the three topological indices are characterized.
This research is supported by the National Natural Science Foundation of China(10471037)and the Education Committee of Hunan
Province(02C210)(04B047). 相似文献
996.
A (n, n + 1)-graph G is a connected simple graph with n vertices and n + 1 edges. If d
v
denotes the degree of the vertex v, then the zeroth-order general Randić index
of the graph G is defined as
, where α is a real number. We characterize, for any α, the (n,n + 1)-graphs with the smallest and greatest zeroth-order general Randić index. 相似文献
997.
Natalini B Sardella R Camaioni E Gioiello A Pellicciari R 《Analytical and bioanalytical chemistry》2007,388(8):1681-1688
The discovery that bile acids are involved in the modulation of nuclear steroid receptors has prompted renewed interest in
this field of research. Due to the nature of research in this field, a technique that enables simple and effective assessment
of the hydrophobic/hydrophilic balance, thus improving and speeding up evaluations of the biological profiles of these compounds,
is greatly needed. In this context, both CMC value determination and RP-HPLC mobility evaluation were explored as possible
approaches. While the CMC was calculated using the noninvasive conductimetric method, the RP-HPLC mobility was assessed by
measuring the retention factor at several mobile phase compositions and extrapolating back to the pure aqueous mobile phase.
The correlation of the CMC with the derived chromatographic hydrophobic index ϕ
0 was satisfactory.
Figure Experimental versus predicted pCMC values 相似文献
998.
Alexander Alldridge 《Journal of Functional Analysis》2007,249(2):425-453
We study multivariate generalisations of the classical Wiener-Hopf algebra, which is the C∗-algebra generated by the Wiener-Hopf operators, given by convolutions restricted to convex cones. By the work of Muhly and Renault, this C∗-algebra is known to be isomorphic to the reduced C∗-algebra of a certain restricted action groupoid, given by the action of Euclidean space on a certain compactification. Using groupoid methods, we construct composition series for the Wiener-Hopf C∗-algebra by a detailed study of this compactification. We compute the spectrum, and express homomorphisms in K-theory induced by the symbol maps which arise by the subquotients of the composition series in analytical terms. Namely, these symbols maps turn out to be given by an analytical family index of a continuous family of Fredholm operators. In a subsequent paper, we also obtain a topological expression of these indices. 相似文献
999.
Let be an integral projective curve. One defines the speciality index e(C) of C as the maximal integer t such that , where ω
C
denotes the dualizing sheaf of . Extending a classical result of Halphen concerning the speciality of a space curve, in the present paper we prove that
if is an integral degree d curve not contained in any surface of degree < s, in any threefold of degree < t, and in any fourfold of degree < u, and if , then Moreover equality holds if and only if C is a complete intersection of hypersurfaces of degrees u, , and . We give also some partial results in the general case , .
相似文献
1000.
Let G(k, n) be the set of connected graphs without multiple edges or loops which have n vertices and the minimum degree of vertices is k. The Randi? index χ = χ(G) of a graph G is defined by χ(G)=∑(uv)(δuδv)-1/2, where δu is the degree of vertex u and the summation extends over all edges (uv) of G. Caporossi et al. [G. Caporossi, I. Gutman, P. Hansen, Variable neighborhood search for extremal graphs IV: Chemical trees with extremal connectivity index, Computers and Chemistry 23 (1999) 469–477] proposed the use of linear programming as one of the tools for finding the extremal graphs. In this paper we introduce a new approach based on quadratic programming for finding the extremal graphs in G(k, n) for this index. We found the extremal graphs or gave good bounds for this index when the number nk of vertices of degree k is between n − k and n. We also tried to find the graphs for which the Randi? index attained its minimum value with given k (k ? n/2) and n. We have solved this problem partially, that is, we have showed that the extremal graphs must have the number nk of vertices of degree k less or equal n − k and the number of vertices of degree n − 1 less or equal k. 相似文献