全文获取类型
收费全文 | 116764篇 |
免费 | 6123篇 |
国内免费 | 5959篇 |
专业分类
化学 | 54023篇 |
晶体学 | 1431篇 |
力学 | 8556篇 |
综合类 | 465篇 |
数学 | 36420篇 |
物理学 | 27951篇 |
出版年
2024年 | 83篇 |
2023年 | 632篇 |
2022年 | 1055篇 |
2021年 | 1214篇 |
2020年 | 1392篇 |
2019年 | 1427篇 |
2018年 | 11418篇 |
2017年 | 11241篇 |
2016年 | 7585篇 |
2015年 | 2608篇 |
2014年 | 2398篇 |
2013年 | 3194篇 |
2012年 | 7028篇 |
2011年 | 13955篇 |
2010年 | 8243篇 |
2009年 | 8531篇 |
2008年 | 9376篇 |
2007年 | 11263篇 |
2006年 | 2535篇 |
2005年 | 3310篇 |
2004年 | 3105篇 |
2003年 | 3251篇 |
2002年 | 2344篇 |
2001年 | 1388篇 |
2000年 | 1211篇 |
1999年 | 950篇 |
1998年 | 836篇 |
1997年 | 681篇 |
1996年 | 788篇 |
1995年 | 587篇 |
1994年 | 526篇 |
1993年 | 481篇 |
1992年 | 417篇 |
1991年 | 380篇 |
1990年 | 306篇 |
1989年 | 270篇 |
1988年 | 243篇 |
1987年 | 210篇 |
1986年 | 212篇 |
1985年 | 218篇 |
1984年 | 152篇 |
1983年 | 110篇 |
1982年 | 121篇 |
1981年 | 94篇 |
1980年 | 101篇 |
1979年 | 109篇 |
1978年 | 79篇 |
1976年 | 58篇 |
1974年 | 53篇 |
1973年 | 72篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
41.
Norbornene derivatives from a metal‐free,strain‐promoted cycloaddition reaction: New building blocks for ring‐opening metathesis polymerization reactions
下载免费PDF全文
![点击此处可从《Journal of polymer science. Part A, Polymer chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Christopher E. Hobbs Binhong Lin Thomas Malinski 《Journal of polymer science. Part A, Polymer chemistry》2015,53(20):2357-2362
The preparation of new ring opening metathesis polymerization (ROMP) monomers using a 1,3‐dipolar cycloaddition between aryl azides and norbornadiene is described. Various norbornenetriazolines, obtained through a solvent‐and catalyst‐free reaction, can subsequently be incorporated into polymer backbones through ROMP reactions. Furthermore, thermal decomposition of the triazoline moiety can allow for further polymer functionalization. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2357–2362 相似文献
42.
43.
44.
Dong Liangwei Qi Wei Peng Ping Wang Linxue Zhou Hui Huang Changming 《Nonlinear dynamics》2020,102(1):303-310
Nonlinear Dynamics - We address the nonlinear dynamics of binary Bose-Einstein condensates with mutually symmetric spinor components trapped in an optical lattice. The interaction between the... 相似文献
45.
Hejia Hu Linlin Wu Mei Li Cun Xue Guangcheng Wang Siying Chen Yong Huang Lin Zheng Aimin Wang Yueting Li Zipeng Gong 《Biomedical chromatography : BMC》2020,34(1):e4714
Eucommia ulmoides Oliv. (E. ulmoides) is a valuable and nourishing medicinal herb in China that has been used in the treatment of hypertension. Given the fact that most traditional Chinese medicine is mainly used to treat disease, investigating the pharmacokinetics of traditional Chinese medicines in the pathological state is more useful than that in the normal state. However, the differences in the absorption kinetics of active ingredients of E. ulmoides extract between pathological and physiological conditions have not been reported. Therefore, in this study, the rat intestinal in situ circulatory perfusion model was used to investigate the differences in absorption kinetics of seven active ingredients of E. ulmoides extract in normal and spontaneously hypertensive rats, namely, genipinic acid, protocatechuic acid, neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, (+)-pinoresinol di-O-β-D -glucopyranoside and (+)-pinoresinol 4′-O-β-D -glucopyranoside. Our results indicate that the pathological state of spontaneous hypertension may change the absorption of active components of E. ulmoides extracts, and these findings may provide a reference for improving the rational use of E. ulmoides in the clinic. 相似文献
46.
47.
48.
Lan-Lan Zhang Dr. Wen-Ke Miao Dr. Li-Jun Ren Yu-Kun Yan Dr. Yue Lin Prof. Wei Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(58):13396-13401
Organic polymers and inorganic clusters belong to two different disciplines and have completely different properties and structures. When a cluster is attached to the backbone of a polymer as a pendant, the resultant hybrid polymers (polyclusters) exhibit unique behaviours totally different from those of conventional polymers owing to the nanoscale size of the cluster and its particular interactions. Herein, the aggregation of a poly(polyoxometalate)—a polynorbornene backbone with inorganic polyoxometalate cluster pendants—upon addition of a non-solvent to its dilute solution is reported. A three-dimensional network of tangled and snake-like nanothreads was observed. Direct visualisation of individual nanoscale clusters enabled identification of single chains within the nanothreads. These observations suggest that during the process of aggregation, the hybrid polymer forms curved or extended chains as a consequence of an armouring effect in which the collapsed cluster pendants wrap around the backbone. The collapse occurs because they become less soluble in the solvent/non-solvent mixture. The extended chains then become entwined and form nanoropes consisting of multiple chains wound around each other. This study provides a deeper understanding of the nature of polyclusters and should also prove useful for their future development and application. 相似文献
49.
50.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films
were investigated using a number of techniques. A high saturation magnetic induction up to B
s
= 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed,
which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of
the composition.
The text was submitted by the authors in English. 相似文献