全文获取类型
收费全文 | 85440篇 |
免费 | 889篇 |
国内免费 | 158篇 |
专业分类
化学 | 46563篇 |
晶体学 | 1288篇 |
力学 | 3557篇 |
综合类 | 1篇 |
数学 | 9103篇 |
物理学 | 25975篇 |
出版年
2022年 | 720篇 |
2021年 | 1018篇 |
2020年 | 1107篇 |
2019年 | 1269篇 |
2018年 | 1721篇 |
2017年 | 1798篇 |
2016年 | 2421篇 |
2015年 | 1225篇 |
2014年 | 1963篇 |
2013年 | 3730篇 |
2012年 | 3380篇 |
2011年 | 3779篇 |
2010年 | 2933篇 |
2009年 | 2906篇 |
2008年 | 3441篇 |
2007年 | 3348篇 |
2006年 | 3183篇 |
2005年 | 2795篇 |
2004年 | 2575篇 |
2003年 | 2368篇 |
2002年 | 2389篇 |
2001年 | 2333篇 |
2000年 | 1721篇 |
1999年 | 1340篇 |
1998年 | 1204篇 |
1997年 | 1111篇 |
1996年 | 990篇 |
1995年 | 904篇 |
1994年 | 862篇 |
1993年 | 855篇 |
1992年 | 907篇 |
1991年 | 990篇 |
1990年 | 932篇 |
1989年 | 946篇 |
1988年 | 846篇 |
1987年 | 799篇 |
1986年 | 780篇 |
1985年 | 908篇 |
1984年 | 1012篇 |
1983年 | 861篇 |
1982年 | 888篇 |
1981年 | 791篇 |
1980年 | 759篇 |
1979年 | 810篇 |
1978年 | 935篇 |
1977年 | 973篇 |
1976年 | 848篇 |
1975年 | 816篇 |
1974年 | 819篇 |
1973年 | 791篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Patrick Imrie Jianyong Jin 《Journal of polymer science. Part A, Polymer chemistry》2022,60(2):149-174
4D printing is an exciting branch of additive manufacturing. It relies on established 3D printing techniques to fabricate objects in much the same way. However, structures which fall into the 4D printed category have the ability to change with time, hence the “extra dimension.” The common perception of 4D printed objects is that of macroscopic single-material structures limited to point-to-point shape change only, in response to either heat or water. However, in the area of polymer 4D printing, recent advancements challenge this understanding. A host of new polymeric materials have been designed which display a variety of wonderful effects brought about by unconventional stimuli, and advanced additive manufacturing techniques have been developed to accommodate them. As a result, the horizons of polymer 4D printing have been broadened beyond what was initially thought possible. In this review, we showcase the many studies which evolve the very definition of polymer 4D printing, and reveal emerging areas of research integral to its advancement. 相似文献
2.
Gaineev A. M. Galkina I. V. Davletshin R. R. Davletshina N. V. Kuznetsov N. O. Grishaev D. Yu. Shulayeva M. P. Pozdeev O. K. 《Russian Journal of General Chemistry》2022,92(7):1208-1213
Russian Journal of General Chemistry - Aminophosphabetaines, i.e., isobutyl {[alkyl(dimethyl)ammonio]methyl}phosphonates with higher alkyl substituents at the nitrogen atom, were obtained by a... 相似文献
3.
Kinetics and Catalysis - The results of studies in the field of synthesis and characterization of layered double hydroxides (LDHs) obtained using solid-phase reactions are summarized. The effect of... 相似文献
4.
Hassan E. A. M. Elabid A. E. A. Bashier E. O. Elagib T. H. H. 《Mechanics of Composite Materials》2022,58(2):261-270
Mechanics of Composite Materials - Carbon fiber (CF)/ polyamide (PA6) composites are one of the most promising thermoplastic materials for automobile applications. However, the interfacial... 相似文献
5.
Dr. Jordan Donat Mr. Patrick Dubourdeaux Dr. Martin Clémancey Dr. Julia Rendon Clara Gervasoni Mr. Morgan Barbier Jessica Barilone Dr. Jacques Pécaut Prof. Dr. Serge Gambarelli Prof. Dr. Pascale Maldivi Prof. Dr. Jean-Marc Latour 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(70):e202201875
Nitrene transfer reactions have emerged as one of the most powerful and versatile ways to insert an amine function to various kinds of hydrocarbon substrates. However, the mechanisms of nitrene generation have not been studied in depth albeit their formation is taken for granted in most cases without definitive evidence of their occurrence. In the present work, we compare the generation of tosylimido iron species and NTs transfer from FeII and FeIII precursors where the metal is embedded in a tetracarbene macrocycle. Catalytic nitrene transfer to reference substrates (thioanisole, styrene, ethylbenzene and cyclohexane) revealed that the same active species was at play, irrespective of the ferrous versus ferric nature of the precursor. Through combination of spectroscopic (UV-visible, Mössbauer), ESI-MS and DFT studies, an FeIV tosylimido species was identified as the catalytically active species and was characterized spectroscopically and computationally. Whereas its formation from the FeII precursor was expected by a two-electron oxidative addition, its formation from an FeIII precursor was unprecedented. Thanks to a combination of spectroscopic (UV-visible, EPR, Hyscore and Mössbauer), ESI-MS and DFT studies, we found that, when starting from the FeIII precursor, an FeIII tosyliodinane adduct was formed and decomposed into an FeV tosylimido species which generated the catalytically active FeIV tosylimide through a comproportionation process with the FeIII precursor. 相似文献
6.
Tsyganova S. I. Fetisova O. Yu. Mazurova E. N. Taran O. P. Kuznetsov B. N. 《Russian Journal of Applied Chemistry》2022,95(3):408-416
Russian Journal of Applied Chemistry - A method for the disposal of hydrolysis lignin waste based on its modification with ZnCl2 and FeCl3 and subsequent carbonization at 800°C was proposed.... 相似文献
7.
Mathematical Notes - Subspaces of the space of analytic functions on a convex domain in the complex plane that are invariant with respect to the differentiation operator are studied. The problem of... 相似文献
8.
Daulbaev O. Isaenko L. I. Bogdzel’ A. A. Lobanov S. I. Krinitsyn P. G. Milkov V. M. Belushkin A. V. 《Crystallography Reports》2022,67(3):464-469
Crystallography Reports - Two LiInSe2 single crystals, grown under different conditions, have been studied. Characteristics of these crystals for neutron detection have been compared using... 相似文献
9.
Kolesnikov A. O. Shatokhin A. N. Vishnyakov E. A. Ragozin E. N. 《Journal of Russian Laser Research》2022,43(4):467-475
Journal of Russian Laser Research - We analyze the way of advancing to tender X-rays the short-wavelength bound of the operating range of flat-field grating spectrographs. We design two VLS grating... 相似文献
10.
Ukrainian Mathematical Journal - We establish new criteria of compatibility for a linear system of equations (equivalent to the Kronecker–Capelli theorem) or inequalities (equivalent to the... 相似文献