全文获取类型
收费全文 | 168120篇 |
免费 | 1819篇 |
国内免费 | 500篇 |
专业分类
化学 | 86328篇 |
晶体学 | 2254篇 |
力学 | 7108篇 |
综合类 | 3篇 |
数学 | 19392篇 |
物理学 | 55354篇 |
出版年
2020年 | 1405篇 |
2019年 | 1558篇 |
2018年 | 1984篇 |
2017年 | 2067篇 |
2016年 | 3193篇 |
2015年 | 1892篇 |
2014年 | 3123篇 |
2013年 | 7667篇 |
2012年 | 5763篇 |
2011年 | 6889篇 |
2010年 | 5028篇 |
2009年 | 5008篇 |
2008年 | 6542篇 |
2007年 | 6436篇 |
2006年 | 6084篇 |
2005年 | 5512篇 |
2004年 | 5104篇 |
2003年 | 4501篇 |
2002年 | 4090篇 |
2001年 | 5047篇 |
2000年 | 3655篇 |
1999年 | 2732篇 |
1998年 | 2284篇 |
1997年 | 2243篇 |
1996年 | 2052篇 |
1995年 | 2054篇 |
1994年 | 2047篇 |
1993年 | 1944篇 |
1992年 | 2226篇 |
1991年 | 2176篇 |
1990年 | 2124篇 |
1989年 | 2056篇 |
1988年 | 2063篇 |
1987年 | 2061篇 |
1986年 | 1962篇 |
1985年 | 2583篇 |
1984年 | 2629篇 |
1983年 | 2315篇 |
1982年 | 2444篇 |
1981年 | 2251篇 |
1980年 | 2235篇 |
1979年 | 2394篇 |
1978年 | 2431篇 |
1977年 | 2375篇 |
1976年 | 2422篇 |
1975年 | 2345篇 |
1974年 | 2311篇 |
1973年 | 2482篇 |
1972年 | 1602篇 |
1971年 | 1322篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
JETP Letters - The behavior of an NdFeB-based multicomponent alloy subjected to high-pressure torsion has been studied. The high-pressure torsion results in the partial amorphization of the alloy,... 相似文献
82.
Journal of Analytical Chemistry - We review the main techniques, procedures, and information products used in non-target analysis (NTA) to reveal the composition of substances. Sampling and sample... 相似文献
83.
Dr. Yulia Y. Enakieva Dr. Anna A. Sinelshchikova Prof. Mikhail S. Grigoriev Prof. Vladimir V. Chernyshev Dr. Konstantin A. Kovalenko Prof. Irina A. Stenina Prof. Andrey B. Yaroslavtsev Prof. Yulia G. Gorbunova Prof. Aslan Y. Tsivadze 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(45):10552-10556
The design of new solid-state proton-conducting materials is a great challenge for chemistry and materials science. Herein, a new anionic porphyrinylphosphonate-based MOF ( IPCE-1Ni ), which involves dimethylammonium (DMA) cations for charge compensation, is reported. As a result of its unique structure, IPCE-1Ni exhibits one of the highest value of the proton conductivity among reported proton-conducting MOF materials based on porphyrins (1.55×10−3 S cm−1 at 75 °C and 80 % relative humidity). 相似文献
84.
Matveev Vladimir B. Semenov-Tian-Shansky Michel 《Letters in Mathematical Physics》2019,109(6):1269-1270
Letters in Mathematical Physics - 相似文献
85.
Mykhaylychenko Sergiy S. Markitanov Yuriy N. Rudenko Timofii V. Rusanov Eduard B. Shermolovich Yuriy G. 《Chemistry of Heterocyclic Compounds》2019,55(2):189-192
Chemistry of Heterocyclic Compounds - New 4-polyfluoroalkyl-1,3-dithiolanes were synthesized by reaction of polyfluoroalkanethioamides with thiocarbonyl ylide that was generated in situ by... 相似文献
86.
Farnesene (Far) is a bio‐based terpene monomer that is similar in structure to commercially used dienes like butadiene and isoprene. Nitroxide‐mediated polymerization (NMP) is adept for the polymerization of dienes, but not particularly effective at controlling the polymerization of methacrylates using commercial nitroxides. In this study, Far is statistically copolymerized with a functional methacrylate, glycidyl methacrylate (GMA), by NMP using N‐succinimidyl modified commercial BlocBuilder (NHS‐BB) initiator. Reactivity ratios are determined to be r Far = 0.54 ± 0.04 and r GMA = 0.24 ± 0.02. The ability of the poly(Far‐stat‐GMA) chains to reinitiate for chain extension with styrene showed a clear shift in molecular weight and monomodal distribution. Copolymerizations using a new alkoxyamine, Dispolreg 007 (D7), is explored as it is shown to homopolymerize methacrylates, but not yet reported for statistical copolymerizations. Bimodal molecular weight distributions are observed when an equimolar ratio of Far and GMA is copolymerized with D7 due to slow decomposition of the initiator, but chain ends are active as shown by successful chain extension with styrene. Both NHS‐BB and D7 initiators are used to synthesize poly[Far‐b‐(GMA‐stat‐Far)] and poly(Far‐b‐GMA) diblock copolymers. While the NHS‐BB initiated polymer chains have lower dispersity, D7 exhibits more linear polymerization kinetics and maintains more active chain ends. 相似文献
87.
Crystallography Reports - Temperature measurements (in the range of 375–830 K) of the ionic conductivity of terbium trifluoride single crystals (structure type β-YF3) along three... 相似文献
88.
Kaminskii A. A. Manomenova V. L. Rudneva E. B. Sorokina N. I. Grebenev V. V. Kozlova N. N. Angeluts A. A. Ozheredov I. A. Solyankin P. M. Denisyuk I. Yu. Fokina M. I. Zulina N. A. Shkurinov A. P. Voloshin A. E. 《Crystallography Reports》2019,64(4):669-677
Crystallography Reports - Aqueous solutions of guanylurea hydrogen phosphite (GUHP) have been synthesized. The temperature dependence of equilibrium GUHP concentration in water was obtained. The... 相似文献
89.
Russian Journal of General Chemistry - Reactions of 2-and 3-furoyl chlorides having chloromethyl or butylthiomethyl group in the adjacent position of the furan ring as well as of analogous... 相似文献
90.
General dual curvature measures have recently been introduced by Lutwak, Yang and Zhang [24]. These new measures unify several other geometric measures of the Brunn–Minkowski theory and the dual Brunn–Minkowski theory. dual curvature measures arise from qth dual intrinsic volumes by means of Alexandrov-type variational formulas. Lutwak, Yang and Zhang [24] formulated the dual Minkowski problem, which concerns the characterization of dual curvature measures. In this paper, we solve the existence part of the dual Minkowski problem for and , and we also discuss the regularity of the solution. 相似文献