全文获取类型
收费全文 | 385270篇 |
免费 | 3260篇 |
国内免费 | 1063篇 |
专业分类
化学 | 199424篇 |
晶体学 | 6449篇 |
力学 | 17425篇 |
综合类 | 12篇 |
数学 | 43752篇 |
物理学 | 122531篇 |
出版年
2021年 | 3547篇 |
2020年 | 4026篇 |
2019年 | 4456篇 |
2018年 | 5384篇 |
2017年 | 5589篇 |
2016年 | 7981篇 |
2015年 | 4526篇 |
2014年 | 7516篇 |
2013年 | 17989篇 |
2012年 | 13559篇 |
2011年 | 16423篇 |
2010年 | 11884篇 |
2009年 | 11842篇 |
2008年 | 14620篇 |
2007年 | 14499篇 |
2006年 | 13575篇 |
2005年 | 12004篇 |
2004年 | 10955篇 |
2003年 | 9771篇 |
2002年 | 9726篇 |
2001年 | 11538篇 |
2000年 | 8738篇 |
1999年 | 6690篇 |
1998年 | 5557篇 |
1997年 | 5418篇 |
1996年 | 5121篇 |
1995年 | 4587篇 |
1994年 | 4448篇 |
1993年 | 4240篇 |
1992年 | 4973篇 |
1991年 | 5067篇 |
1990年 | 4822篇 |
1989年 | 4869篇 |
1988年 | 4708篇 |
1987年 | 4710篇 |
1986年 | 4484篇 |
1985年 | 5703篇 |
1984年 | 5757篇 |
1983年 | 4622篇 |
1982年 | 4851篇 |
1981年 | 4747篇 |
1980年 | 4485篇 |
1979年 | 4895篇 |
1978年 | 4940篇 |
1977年 | 4962篇 |
1976年 | 4916篇 |
1975年 | 4559篇 |
1974年 | 4472篇 |
1973年 | 4521篇 |
1972年 | 3155篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Soldatova A. E. Tsegelskaya A. Yu. Semenova G. K. Bezsudnov I. V. Polinskaya M. S. Abramov I. G. Kuznetsov A. A. 《Russian Chemical Bulletin》2022,71(4):777-786
Russian Chemical Bulletin - The method of one-stage catalytic polycyclocondensation according to the B4 + AB scheme was used to synthesize new tetraarm star-shaped oligoimides (SOIs) with terminal... 相似文献
132.
Kalinin A. A. Sharipova S. M. Islamova L. N. Fazleeva G. M. Busyurova D. N. Sharipova A. V. Fominykh O. D. Balakina M. Yu. 《Russian Chemical Bulletin》2022,71(5):1009-1018
Russian Chemical Bulletin - Two new D—π—A chromophores with the tricyanofuranyl acceptor (A), an amphi-divinyl quinoxaline π-electron conjugated bridge, and the carbazole or... 相似文献
133.
Ceren Kütahya Nicolai Meckbach Veronika Strehmel Bernd Strehmel 《Journal of polymer science. Part A, Polymer chemistry》2021,59(18):2023-2035
Cyanines with heptamethine pattern namely 5-(6-(2-(3-ethyl-1,1-dimethyl-1H-benzo[e]indol-2(3H)-ylidene)ethylidene)-2-(2-(3-ethyl-1,1-dimethyl-1H-benzo[e]indol-3-ium-2yl) vinyl) cyclo-hex-1-en-1-yl)-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-olate comprising a barbiturate group facilitate controlled radical polymerization using FeBr3 in the ppm range applying radiation at 790 nm. Tris(4-methoylphenyl)phosphine, Tris(2-pyridylmethyl)amine or tetrabutylammonium bromide served as ligand. The latter showed the best performance resulting in a system needing no amino nitrogen for photo-ATRP. Ethyl α-bromophenylacetate worked as initiator. The cyanine interacts with FeBr3 resulting in a new absorption band at 877 nm that also resulted in formation of polymer exhibiting similar molecular weight but higher dispersity compared to that obtained by 790 nm radiation by exposure with a light-emitting diode (LED) emitting at 870 nm. This explains the reactivity of the system while other cyanines such as 2-[2-[3-[2-(1,3-Dihydro-1,3,3-trimethyl-2H-indol-2-ylidene)-ethylidene]-2-(1-phenyl- 1H-tetrazol-5-ylsulfanyl)-1-cyclohexen-1-yl]-ethenyl]-1,3,3-trimethyl-3H-indolium chloride showed no activity by exposure at 790 nm in combination with FeBr3/Br−. Controlled radical polymerization was confirmed by successful chain extension and block copolymerization experiments resulting in polymers, which exhibit a dispersity of about 1.3. Interestingly, the new system comprising the aforementioned barbiturate substituted cyanine, FeBr3/Br− and ethyl α-bromophenylacetate showed a certain oxygen tolerance. Polymers obtained exhibited similar dispersity as those made under inert conditions. 相似文献
134.
Klimova A. V. Mikhailovskaya Z. A. Buyanova E. S. Petrova S. A. 《Russian Journal of Electrochemistry》2021,57(8):825-832
Russian Journal of Electrochemistry - The possibility of synthesizing oxygen-ion conductors based on bismuth molybdate with antimony and tin substituted to the molybdenum sublattice is studied and... 相似文献
135.
Ukhin L. Yu. Kuz’mina L. G. Alexeenko D. V. Belousova L. V. Gribanova T. N. Morkovnik A. S. Shepelenko E. N. Borodkin G. S. Dmitrieva O. I. Podshibyakin V. A. 《Russian Chemical Bulletin》2021,70(7):1368-1376
Russian Chemical Bulletin - New potential biologically active derivatives, in which the sterically hindered pyrocatechol moiety is linked through a 2-thioacetyl covalent bridge to a number of... 相似文献
136.
Novakov I. A. Sheikin D. S. Ruchko E. A. Brunilina L. L. Vernigora A. A. Salykin N. A. Vostrikova O. V. Chapurkin V. V. Nawrozkij M. B. Kurkin D. V. Bakulin D. A. Vorontsov M. Yu. Sablina L. A. Kovalev N. S. Tyurenkov I. N. 《Russian Chemical Bulletin》2021,70(11):2220-2226
Russian Chemical Bulletin - Novel structural analogs of isothiobarbamine, which differ from the prototype scaffold by the substituent at position 2 of the pyrimidine heterocycle, were for the first... 相似文献
137.
Journal of Analytical Chemistry - We validated a procedure for the determination of indicator congeners (ICs) of polychlorinated biphenyls (PCBs) (IUPAC nos. 28, 52, 101, 118, 138, 153, and 180) in... 相似文献
138.
Sizova A. A. Grintsevich S. A. Kochurin M. A. Sizov V. V. Brodskaya E. N. 《Colloid Journal》2021,83(3):372-378
Colloid Journal - Grand canonical Monte Carlo simulations were performed to study the occupancy of structure I multicomponent gas hydrates by CO2/CH4, CO2/N2, and N2/CH4 binary gas mixtures with... 相似文献
139.
Colloid Journal - The influence of the concentration and size of magnetite nanoparticles on the stability of highly concentrated water-in-oil emulsions containing styrene–divinylbenzene... 相似文献
140.
Mironova M. V. Shandryuk G. A. Meshkov I. B. Shabeko A. A. Makarov I. S. Kulichikhin V. G. Muzafarov A. M. 《Russian Chemical Bulletin》2021,70(11):2200-2207
Russian Chemical Bulletin - Highly filled vulcanizates based on polyisoprene, organosilicon fillers (polymethylsilsesquioxane and MQ-copolymers), and p-quinone dioxime derivative as a rubber... 相似文献