全文获取类型
收费全文 | 4601篇 |
免费 | 803篇 |
国内免费 | 501篇 |
专业分类
化学 | 3415篇 |
晶体学 | 41篇 |
力学 | 224篇 |
综合类 | 51篇 |
数学 | 491篇 |
物理学 | 1683篇 |
出版年
2024年 | 13篇 |
2023年 | 82篇 |
2022年 | 170篇 |
2021年 | 137篇 |
2020年 | 186篇 |
2019年 | 207篇 |
2018年 | 162篇 |
2017年 | 134篇 |
2016年 | 250篇 |
2015年 | 210篇 |
2014年 | 274篇 |
2013年 | 307篇 |
2012年 | 379篇 |
2011年 | 373篇 |
2010年 | 271篇 |
2009年 | 293篇 |
2008年 | 314篇 |
2007年 | 274篇 |
2006年 | 258篇 |
2005年 | 226篇 |
2004年 | 163篇 |
2003年 | 144篇 |
2002年 | 181篇 |
2001年 | 152篇 |
2000年 | 93篇 |
1999年 | 103篇 |
1998年 | 68篇 |
1997年 | 60篇 |
1996年 | 71篇 |
1995年 | 45篇 |
1994年 | 56篇 |
1993年 | 36篇 |
1992年 | 22篇 |
1991年 | 43篇 |
1990年 | 38篇 |
1989年 | 29篇 |
1988年 | 12篇 |
1987年 | 13篇 |
1986年 | 11篇 |
1985年 | 19篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1970年 | 1篇 |
1966年 | 1篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1959年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有5905条查询结果,搜索用时 0 毫秒
91.
92.
93.
Chang-Sheng Zhang Ya-Ping Shao Fu-Min Zhang Xue Han Xiao-Ming Zhang Kun Zhang Yong-Qiang Tu 《Chemical science》2022,13(28):8429
A novel classical kinetic resolution of 2-aryl-substituted or 2,3-disubstituted cyclobutanones of Baeyer–Villiger oxidation catalyzed by a Cu(ii)/SPDO complex is reported for the first time, producing normal lactones in excellent enantioselectivities (up to 96% ee) and regioselectivities (up to >20/1), along with unreacted ketones in excellent enantioselectivities (up to 99% ee). The current transformation features a wide substrate scope. Moreover, catalytic asymmetric total syntheses of natural eupomatilones 5 and 6 are achieved in nine steps from commercially available 3-methylcyclobutan-1-one.A novel classical kinetic resolution of Baeyer–Villiger oxidation catalyzed by a Cu(ii)/SPDO complex with excellent enantioselectivity, regioselectivity and wide substrate scope is reported for the first time and explore the synthetic application. 相似文献
94.
Bin-Long Sun Ying-Ying Wang Sen Yang Min-Ting Tu Ying-Ying Shao Yi Hua Yi Zhou Cheng-Xia Tan 《Molecules (Basel, Switzerland)》2022,27(12)
To develop new compounds with high activity, broad spectrum and low-toxicity, 17 benzamides substituted with quinoline-linked 1,2,4-oxadiazole were designed using the splicing principle of active substructures and were synthesized. The biological activities were evaluated against 10 fungi, indicating that some of the synthetic compounds showed excellent fungicidal activities. For example, at 50 mg/L, the inhibitory activity of 13p (3-Cl-4-Cl substituted, 86.1%) against Sclerotinia sclerotiorum was superior to that of quinoxyfen (77.8%), and the inhibitory activity of 13f (3-CF3 substituted, 77.8%) was comparable to that of quinoxyfen. The fungicidal activities of 13f and 13p to Sclerotinia sclerotiorum were better than that of quinoxyfen (14.19 mg/L), with EC50 of 6.67 mg/L and 5.17 mg/L, respectively. Furthermore, the acute toxicity of 13p was 19.42 mg/L, classifying it as a low-toxic compound. 相似文献
95.
Yongle Zhao Huichen Xie Wenwen Shi Hong Wang Chenyi Shao Can Li 《Journal of Energy Chemistry》2022,(1):33-37
Tantalum nitride(Ta3N5) is a very promising photoanode material due to its narrow band gap(2.1 eV)and suitable band alignment for solar water splitting.However,it suffers from severe photocorrosion during water oxidation.In this work,it was found that surface passivation by AlOx and TiOx layers results in dramatically different PEC performance of Ta3N5 photoanode for water oxidation.The mechanism study indicates that the negative ... 相似文献
96.
Dr. Qicai Xiao Dr. Wei Du Dr. Xiao Dong Dr. Shubo Du Sing Yee Ong Dr. Guanghui Tang Dr. Changyu Zhang Dr. Fen Yang Prof. Dr. Lin Li Prof. Dr. Liqian Gao Prof. Dr. Shao Q. Yao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(47):12207-12214
Mitochondria are key organelles that perform vital cellular functions such as those related to cell survival and death. The targeted delivery of different types of cargos to mitochondria is a well-established strategy to study mitochondrial biology and diseases. Of the various existing mitochondrion-transporting vehicles, most suffer from poor cytosolic entry, low delivery efficiency, limited cargo types, and cumbersome preparation protocols, and none was known to be universally applicable for mitochondrial delivery of different types of cargos (small molecules, proteins, and nanomaterials). Herein, two new cell-penetrating, mitochondrion-targeting ligands (named MitoLigand) that are capable of effectively “tagging” small-molecule drugs, native proteins and nanomaterials are disclosed, as well as their corresponding chemoselective conjugation chemistry. Upon successful cellular delivery and rapid endosome escape, the released native cargos were found to be predominantly localized inside mitochondria. Finally, by successfully delivering doxorubicin, a well-known anticancer drug, to the mitochondria of HeLa cells, we showed that the released drug possessed potent cell cytotoxicity, disrupted the mitochondrial membrane potential and finally led to apoptosis. Our strategy thus paves the way for future mitochondrion-targeted therapy with a variety of biologically active agents. 相似文献
97.
Pua Aileen Goh Rui Min Vivian Ee Kim-Huey Huang Yunle Liu Shao Quan Lassabliere Benjamin Yu Bin 《Chromatographia》2021,84(5):507-515
Chromatographia - The separation of isomers is one of the key issues in analysing complex natural matrices, thus commanding a higher separating power from the applied analytical system. In this... 相似文献
98.
Ping Lv Xin Shen Zhiliyu Cui Bo Li Qiangqiang Xu Zhuo Yu Weijie Lu Haonan Shao Yan Ge Zhenhui Qi 《Journal of polymer science. Part A, Polymer chemistry》2021,59(23):3001-3008
Fiber-reinforced-concrete (FRC) mechanism refers short discrete fibers that are uniformly distributed and randomly oriented, which offers an effective way to improve the mechanical performance of concrete. In the design of supramolecular polymers, an analogous concept of FRC appears to have been considered very rarely-although fibrous structure has been frequently observed/generated during the supramolecular polymerization. In this work, we apply the alkane thermosets, octadecane (C18H38) and tetracosane (C24H50), taking the role of “concrete”, and the low-molecular-weight monomer with long alkyl chains as the essential “fiber” component, to fabricate the “fiber reinforced supramolecular polymer”. Very much like FRC mechanism in material science, the resulting fiber reinforced supramolecular polymer thus exhibit unusually high mechanical strength and stiffness, which is unprecedented in the conventional supramolecular strategy. 相似文献
99.
Dr. Velayudham Ramadoss Yue Zheng Xiaoqing Shao Dr. Lifang Tian Prof. Yahui Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(10):3213-3228
Owing to their non-toxic, stable, inexpensive properties, carboxylic acids are considered as environmentally benign alternatives as coupling partners in various organic transformations. Electrochemical mediated decarboxylation of carboxylic acid has emerged as a new and efficient methodology for the construction of carbon-carbon or carbon-heteroatom bonds. Compared with transition-metal catalysis and photoredox catalysis, electro-organic decarboxylative transformations are considered as a green and sustainable protocol due to the absence of chemical oxidants and strong bases. Further, it exhibits good tolerance with various functional groups. In this Minireview, we summarize the recent advances and discoveries on the electrochemical decarboxylative transformations on C−C and C−heteroatoms bond formations. 相似文献
100.
设计制作了全固态高重复频率磁脉冲压缩发生器,最高重复频率5 kHz,脉宽70 ns,通过调节初始储能电容上的电压可在500 阻性负载上获得4~40 kV连续可调的输出电压。通过分析简化的磁压缩末级回路,分析了预脉冲产生的过程,得出了预脉冲的电压表达式,选取适当的磁芯相对磁导率,经过求解,得出在磁开关未饱和电感一定时预脉冲随负载阻值变化的曲线簇,从曲线中可以看出:随着负载的阻值的增大,预脉冲的峰值绝对值也增大;在负载恒定的情况下,增大磁开关未饱和电感的大小可以显著地减小负载两端预脉冲的峰值绝对值,这要求磁开关磁芯有更高的相对磁导率。 相似文献