全文获取类型
收费全文 | 4479篇 |
免费 | 233篇 |
国内免费 | 35篇 |
专业分类
化学 | 3331篇 |
晶体学 | 25篇 |
力学 | 129篇 |
数学 | 323篇 |
物理学 | 939篇 |
出版年
2023年 | 21篇 |
2022年 | 20篇 |
2021年 | 101篇 |
2020年 | 108篇 |
2019年 | 106篇 |
2018年 | 66篇 |
2017年 | 62篇 |
2016年 | 167篇 |
2015年 | 136篇 |
2014年 | 175篇 |
2013年 | 291篇 |
2012年 | 341篇 |
2011年 | 385篇 |
2010年 | 252篇 |
2009年 | 198篇 |
2008年 | 307篇 |
2007年 | 250篇 |
2006年 | 240篇 |
2005年 | 223篇 |
2004年 | 195篇 |
2003年 | 171篇 |
2002年 | 155篇 |
2001年 | 78篇 |
2000年 | 61篇 |
1999年 | 41篇 |
1998年 | 25篇 |
1997年 | 33篇 |
1996年 | 36篇 |
1995年 | 31篇 |
1994年 | 46篇 |
1993年 | 39篇 |
1992年 | 25篇 |
1991年 | 26篇 |
1990年 | 18篇 |
1989年 | 25篇 |
1988年 | 16篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 26篇 |
1984年 | 22篇 |
1983年 | 16篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 15篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1976年 | 16篇 |
1975年 | 12篇 |
1974年 | 11篇 |
1972年 | 10篇 |
排序方式: 共有4747条查询结果,搜索用时 15 毫秒
1.
Mohammad A. Khalilzadeh Soo Young Kim Ho Won Jang Rafael Luque Rajender S. Varma Richard A. Venditti Mohammadreza Shokouhimehr 《Materials Today Chemistry》2022
The requirement of green and sustainable materials to prepare heterogeneous catalysts has intensified for practical reasons over the past few decades. Carbohydrates are possibly the most plentiful and renewable organic materials in nature with inimitable physiochemical properties, plausible low-cost and large-scale production, and sustainability features could be exploited in the generation of nanostructured heterogeneous catalysts. This review article outlines the organic transformations catalyzed by diverse carbohydrate-based nanostructured catalysts in greener and environmentally friendly processes. Selected examples are highlighted for a variety of organic reactions exploiting the proposed catalysts’ reactivity and reusability, and interactions with the intrinsic nature of the applied carbohydrate supports; advantages and speculated challenges of the introduced catalysts are deliberated as well. 相似文献
2.
Park Kyueun Kim Youngjin Lee Kyung Jin 《Journal of Radioanalytical and Nuclear Chemistry》2019,319(2):487-531
Journal of Radioanalytical and Nuclear Chemistry - An extensive series of evaluations have been performed as part of an IAEA coordinated research project to study a set of nuclear reactions that... 相似文献
3.
The European Physical Journal H - The widespread positivist approach of physics research in Italy at the turn of the XIX and XX centuries did not provide a fertile ground for the scientific debate... 相似文献
4.
Vito Gigante Laura Aliotta Maria Beatrice Coltelli Patrizia Cinelli Luigi Botta Francesco Paolo La Mantia Andrea Lazzeri 《Journal of polymer science. Part A, Polymer chemistry》2020,58(23):3264-3282
The development of biodegradable materials for tailored applications, particularly in the field of polymeric films and sheets, is a challenging technological goal as well as a contribution to help protect the environment. Poly(lactic) acid (PLA) is a promising substitute for several oil-based polymers; however, to overcome its thermal and mechanical drawbacks, researchers have developed solutions such as blending PLA with polybutylene adipate terephthalate (PBAT), which is capable of increasing the ductility of the final material. In this study, PLA/PBAT binary blends, with minimum possible content of nonrenewable materials, were examined from processing, thermal, morphological, and rheological perspective. An optimized PLA/PBAT ratio was chosen as the polymeric basis to obtain a biodegradable formulation by adding a biobased plasticizer and appropriate fillers to produce a micrometer film with tailored flexibility and tear resistance. The processing technology involved flat-die extrusion, followed by calendering. The tearing resistance of the produced film was investigated, and the results were compared with literature data. A study on the essential work of fracture was implemented to explore the mode III out-of-plane fracture resistance starting from a trouser tear test. 相似文献
5.
Shantaram Kothavale Kyung Hyung Lee Prof. Jun Yeob Lee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(4):845-852
Two efficient thermally activated delayed fluorescent (TADF) emitters were developed by utilizing CN-modified imidazopyridine as an acceptor unit. The CN-modified imidazopyridine acceptor was combined with either an acridine donor or a phenoxazine donor through a phenyl linker to produce two TADF emitters, Ac-CNImPy and PXZ-CNImPy. The acridine-based Ac-CNImPy emitter exhibited sky-blue emission with a CIE coordinate of (0.18, 0.38), whereas the phenoxazine-donor-based PXZ-CNImPy showed greenish-yellow emission with a CIE coordinate of (0.32, 0.58). A high photoluminescence quantum yield of 80 % was observed for the PXZ-CNImPy emitter compared with 40 % for the Ac-CNImPy emitter. Organic light-emitting diodes based on the PXZ-CNImPy emitter demonstrated high external quantum efficiency of 17.0 %. Hence, the CN-modified imidazopyridine unit can be considered as a useful electron acceptor for the future design of highly efficient TADF emitters. 相似文献
6.
7.
8.
9.
Simultaneous analysis of 210 prohibited substances in human urine by ultrafast liquid chromatography/tandem mass spectrometry in doping control 下载免费PDF全文
10.