全文获取类型
收费全文 | 317321篇 |
免费 | 4437篇 |
国内免费 | 1117篇 |
专业分类
化学 | 173155篇 |
晶体学 | 4485篇 |
力学 | 13117篇 |
综合类 | 7篇 |
数学 | 36841篇 |
物理学 | 95270篇 |
出版年
2020年 | 2044篇 |
2019年 | 2025篇 |
2018年 | 2011篇 |
2017年 | 1914篇 |
2016年 | 3957篇 |
2015年 | 3325篇 |
2014年 | 4496篇 |
2013年 | 14129篇 |
2012年 | 10978篇 |
2011年 | 13656篇 |
2010年 | 8386篇 |
2009年 | 8375篇 |
2008年 | 12564篇 |
2007年 | 12796篇 |
2006年 | 12478篇 |
2005年 | 11386篇 |
2004年 | 10230篇 |
2003年 | 9031篇 |
2002年 | 8837篇 |
2001年 | 10153篇 |
2000年 | 7745篇 |
1999年 | 6142篇 |
1998年 | 4926篇 |
1997年 | 4777篇 |
1996年 | 4831篇 |
1995年 | 4394篇 |
1994年 | 4145篇 |
1993年 | 3968篇 |
1992年 | 4457篇 |
1991年 | 4308篇 |
1990年 | 4036篇 |
1989年 | 3845篇 |
1988年 | 4145篇 |
1987年 | 3799篇 |
1986年 | 3692篇 |
1985年 | 5355篇 |
1984年 | 5421篇 |
1983年 | 4393篇 |
1982年 | 4782篇 |
1981年 | 4816篇 |
1980年 | 4564篇 |
1979年 | 4686篇 |
1978年 | 4680篇 |
1977年 | 4656篇 |
1976年 | 4613篇 |
1975年 | 4521篇 |
1974年 | 4365篇 |
1973年 | 4535篇 |
1972年 | 2575篇 |
1971年 | 1881篇 |
排序方式: 共有10000条查询结果,搜索用时 0 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.
Dr. Kyung-Seok Kang Dr. Krishnan A. Iyer Prof. Dr. Jeffrey Pyun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(35):e202200115
In this concept review, the fundamental and polymerization chemistry of inverse vulcanization for the preparation of statistical and segmented sulfur copolymers, which have been actively developed and advanced in various applications over the past decade is discussed. This concept review delves into a discussion of step-growth polymerization constructs to describe the inverse vulcanization process and discuss prepolymer approaches for the synthesis of segmented sulfur polyurethanes. Furthermore, this concept review discusses the advantages of inverse vulcanization in conjunction with dynamic covalent polymerization and post-polymerization modifications to prepare segmented block copolymers with enhanced thermomechanical and flame retardant properties of these materials. 相似文献
3.
Experimental Mechanics - Temperature gradients significantly affect the material fatigue process. A reliable and robust test procedure is needed for quantifying the effects of temperature gradients... 相似文献
4.
Machado J. A. Tenreiro Rocha-Neves J. M. Azevedo Filipe Andrade J. P. 《Nonlinear dynamics》2021,106(2):1525-1555
Nonlinear Dynamics - Given a data-set of Ribonucleic acid (RNA) sequences we can infer the phylogenetics of the samples and tackle the information for scientific purposes. Based on current data and... 相似文献
5.
Kobayashi M. Zhang Y. Ishikawa H. Sun J. Oddershede J. Juul Jensen D. Miura H. 《Experimental Mechanics》2021,61(5):817-828
Experimental Mechanics - The internal strain distribution developing during plastic deformation is important for understanding the mechanical properties of polycrystalline materials. Such... 相似文献
6.
Laguel Yassine Pillutla Krishna Malick Jérôme Harchaoui Zaid 《Set-Valued and Variational Analysis》2021,29(4):967-996
Set-Valued and Variational Analysis - R. Tyrell Rockafellar and his collaborators introduced, in a series of works, new regression modeling methods based on the notion of superquantile (or... 相似文献
7.
8.
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
9.
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10.
S. Venkatesan S. Suresh P. Ramu M. Kandasamy J. Arumugam S. Thambidurai K.M. Prabu N. Pugazhenthiran 《印度化学会志》2022,99(5):100436
A facile biosynthesis route was followed to prepare zinc oxide nanoparticles (ZnO NPs) using Euphorbia milii (E. milii) leaf constituents. The SEM images exhibited presence of spherical ZnO NPs and the corresponding TEM images disclosed monodisperse nature of the ZnO NPs with diameter ranges between 12 and 20 nm. The Brunauer–Emmett–Teller (BET) analysis revealed that the ZnO NPs have specific surface area of 20.46 m2/g with pore diameter of 2 nm–10 nm and pore volume of 0.908 cm3/g. The EDAX spectrum exemplified the existence of Zn and O elements and non-appearance of impurities that confirmed pristine nature of the ZnO NPs. The XRD pattern indicated crystalline peaks corresponding to hexagonal wurtzite structured ZnO with an average crystallite size of 16.11 nm. The FTIR spectrum displayed strong absorption bands at 512 and 534 cm?1 related to ZnO. The photocatalytic action of ZnO NPs exhibited noteworthy degradation of methylene blue dye under natural sunlight illumination. The maximum degradation efficiency achieved was 98.17% at an illumination period of 50 min. The reusability study proved considerable photostability of the ZnO NPs during photocatalytic experiments. These findings suggest that the E. milii leaf constituents can be utilized as suitable biological source to synthesis ZnO NPs for photocatalytic applications. 相似文献