全文获取类型
收费全文 | 131900篇 |
免费 | 1814篇 |
国内免费 | 508篇 |
专业分类
化学 | 73695篇 |
晶体学 | 2084篇 |
力学 | 5147篇 |
综合类 | 6篇 |
数学 | 13048篇 |
物理学 | 40242篇 |
出版年
2016年 | 1464篇 |
2015年 | 1161篇 |
2014年 | 1536篇 |
2013年 | 5134篇 |
2012年 | 3872篇 |
2011年 | 4925篇 |
2010年 | 3045篇 |
2009年 | 2744篇 |
2008年 | 4384篇 |
2007年 | 4447篇 |
2006年 | 4516篇 |
2005年 | 4432篇 |
2004年 | 3846篇 |
2003年 | 3469篇 |
2002年 | 3315篇 |
2001年 | 3660篇 |
2000年 | 2751篇 |
1999年 | 2262篇 |
1998年 | 1947篇 |
1997年 | 1946篇 |
1996年 | 1917篇 |
1995年 | 1831篇 |
1994年 | 1605篇 |
1993年 | 1594篇 |
1992年 | 1802篇 |
1991年 | 1774篇 |
1990年 | 1704篇 |
1989年 | 1707篇 |
1988年 | 1724篇 |
1987年 | 1699篇 |
1986年 | 1617篇 |
1985年 | 2190篇 |
1984年 | 2300篇 |
1983年 | 1913篇 |
1982年 | 2260篇 |
1981年 | 2048篇 |
1980年 | 2095篇 |
1979年 | 2085篇 |
1978年 | 2219篇 |
1977年 | 2119篇 |
1976年 | 2136篇 |
1975年 | 2073篇 |
1974年 | 1917篇 |
1973年 | 2118篇 |
1972年 | 1289篇 |
1971年 | 982篇 |
1970年 | 919篇 |
1969年 | 931篇 |
1968年 | 1054篇 |
1967年 | 1106篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Yang T. L. Kao C. L. Kuo C. E. Yeh H. C. Li W. J. Li H. T. Chen C. Y. 《Chemistry of Natural Compounds》2022,58(5):825-827
Chemistry of Natural Compounds - A novel bibenzyl derivative, hydrangchinenin (1), was isolated from the stems of Hydrangea chinensis Maxim. (Hydrangeaceae). Its structure was determined on the... 相似文献
2.
3.
Theoretical and Mathematical Physics - Dynamic systems acting on the plane and possessing the Wada property have been observed. There exist only two topological types, symmetric and antisymmetric,... 相似文献
4.
5.
Li Y. Shi W. H. Dong L. M. Xu S. X. Huang H. J. Yin J. R. 《Journal of Applied Spectroscopy》2022,89(3):534-541
Journal of Applied Spectroscopy - Sr3B2O6:Dy3+, Eu3+ single-matrix white-light-emitting materials are prepared using the high-temperature solid-state method. The microstructure, emission spectrum,... 相似文献
6.
Ajit Kumar Singh Seulgi Ji Baghendra Singh Chittaranjan Das Heechae Choi Prashanth W. Menezes Arindam Indra 《Materials Today Chemistry》2022
Herein, we report a Mott-Schottky catalyst by entrapping cobalt nanoparticles inside the N-doped graphene shell (Co@NC). The Co@NC delivered excellent oxygen evolution activity with an overpotential of merely 248 mV at a current density of 10 mA cm–2 with promising long-term stability. The importance of Co encapsulated in NC has further been demonstrated by synthesizing Co nanoparticles without NC shell. The synergy between the hexagonal close-packed (hcp) and face-centered cubic (fcc) Co plays a major role to improve the OER activity, whereas the NC shell optimizes the electronic structure, improves the electron conductivity, and offers a large number of active sites in Co@NC. The density functional theory calculations have revealed that the hcp Co has a dominant role in the surface reaction of electrocatalytic oxygen evolution, whereas the fcc phase induces the built-in electric field at the interfaces with N-doped graphene to accelerate the H+ ion transport. 相似文献
7.
Restricted testing conditions were considered recently. For the maximal operator, Hytönen, Li and Sawyer [8] first obtained parental testing condition. Later, they [9] showed that it suffices to restrict testing to doubling cubes. Chen and Lacey [3] gave a similar restricted testing condition. In our paper, we discuss a version of the latter in the multilinear setting.
相似文献8.
9.
Su X. F. Zhang Y. L. Maximov A. L. Zhang K. Xin Q. Feng C. Q. Bai X. F. Wu W. 《Russian Journal of Applied Chemistry》2020,93(1):127-136
Russian Journal of Applied Chemistry - Nanoscale ZSM-5 (AlZ5-D) and Ga-substituted ZSM-5 zeolites ((Al,Ga)Z5-D and GaZ5-D) were synthesized by a green dry-gel conversion strategy. For comparison,... 相似文献
10.
Control over Nanostructures and Associated Mesomorphic Properties of Doped Self‐Assembled Triarylamine Liquid Crystals 下载免费PDF全文
Dr. Yuya Domoto Dr. Eric Busseron Prof. Dr. Mounir Maaloum Dr. Emilie Moulin Prof. Dr. Nicolas Giuseppone 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(5):1938-1948
We have synthesized a series of triarylamine‐cored molecules equipped with an adjacent amide moiety and dendritic peripheral tails in a variety of modes. We show by 1H NMR and UV/Vis spectroscopy that their supramolecular self‐assembly can be promoted in solution upon light stimulation and radical initiation. In addition, we have probed their molecular arrangements and mesomorphic properties in the bulk by integrated studies on their film state by using differential scanning calorimetry (DSC), variable‐temperature polarizing optical microscopy (VT‐POM), variable‐temperature X‐ray diffraction (VT‐XRD), and atomic force microscopy (AFM). Differences in the number and the disposition of the peripheral tails significantly affect their mesomorphic properties associated with their lamellar‐ or columnar‐packed nanostructures, which are based on segregated stacks of the triphenylamine cores and the lipophilic/lipophobic periphery. Such structural tuning is of interest for implementation of these soft self‐assemblies as electroactive materials from solution to mesophases. 相似文献