全文获取类型
收费全文 | 26185篇 |
免费 | 4421篇 |
国内免费 | 3348篇 |
专业分类
化学 | 19142篇 |
晶体学 | 320篇 |
力学 | 1531篇 |
综合类 | 240篇 |
数学 | 3104篇 |
物理学 | 9617篇 |
出版年
2024年 | 30篇 |
2023年 | 475篇 |
2022年 | 586篇 |
2021年 | 780篇 |
2020年 | 980篇 |
2019年 | 1053篇 |
2018年 | 850篇 |
2017年 | 835篇 |
2016年 | 1126篇 |
2015年 | 1163篇 |
2014年 | 1527篇 |
2013年 | 2023篇 |
2012年 | 2406篇 |
2011年 | 2690篇 |
2010年 | 1853篇 |
2009年 | 1856篇 |
2008年 | 1960篇 |
2007年 | 1792篇 |
2006年 | 1549篇 |
2005年 | 1254篇 |
2004年 | 1000篇 |
2003年 | 776篇 |
2002年 | 757篇 |
2001年 | 639篇 |
2000年 | 587篇 |
1999年 | 473篇 |
1998年 | 385篇 |
1997年 | 326篇 |
1996年 | 365篇 |
1995年 | 307篇 |
1994年 | 256篇 |
1993年 | 215篇 |
1992年 | 193篇 |
1991年 | 167篇 |
1990年 | 138篇 |
1989年 | 130篇 |
1988年 | 76篇 |
1987年 | 59篇 |
1986年 | 63篇 |
1985年 | 48篇 |
1984年 | 39篇 |
1983年 | 30篇 |
1982年 | 20篇 |
1981年 | 17篇 |
1980年 | 9篇 |
1979年 | 15篇 |
1977年 | 7篇 |
1976年 | 9篇 |
1975年 | 7篇 |
1957年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
1.
2.
Nonlinear Dynamics - The modal truncation is usually used in the dynamic response analysis of flexible multibody systems, in which, appropriate selection of modal shapes is very critical to achieve... 相似文献
3.
Zheng Xinyan Hu Po Yao Ruxian cheng Jinhe Chang Yiheng Wu Haitao Mei Hongying Sun Shuxiang Chen Qingtai liu Fang Chen Shujing Wen Hua 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(5):2217-2226
Journal of Radioanalytical and Nuclear Chemistry - Enhancement of U(VI) biomineralization by Saccharomyces cerevisiae through addition of inorganic phosphorus was studied in this work. The addition... 相似文献
4.
Science China Chemistry - 相似文献
5.
6.
Given a graph sequence denote by T3(Gn) the number of monochromatic triangles in a uniformly random coloring of the vertices of Gn with colors. In this paper we prove a central limit theorem (CLT) for T3(Gn) with explicit error rates, using a quantitative version of the martingale CLT. We then relate this error term to the well-known fourth-moment phenomenon, which, interestingly, holds only when the number of colors satisfies . We also show that the convergence of the fourth moment is necessary to obtain a Gaussian limit for any , which, together with the above result, implies that the fourth-moment condition characterizes the limiting normal distribution of T3(Gn), whenever . Finally, to illustrate the promise of our approach, we include an alternative proof of the CLT for the number of monochromatic edges, which provides quantitative rates for the results obtained in [7]. 相似文献
7.
Donglei Wei Huili Li Chuanqing Yang Jianmin Fu Hou Chen Liangjiu Bai Wenxiang Wang Huawei Yang Lixia Yang Ying Liang 《Journal of polymer science. Part A, Polymer chemistry》2022,60(10):1588-1594
Acridone as a new kind of visible light photocatalyst has been developed to catalyze metal free atom transfer radical polymerization (ATRP). The photocatalyst possess low excited state potential as can undergo an oxidative quenching pathway to initiate ATRP of vinyl monomers. Kinetic study and light on/off reaction demonstrate the “living”/controlled nature of the polymerization by light. Block copolymers can be achieved by using PMMA as macroinitiator to reinitiate polymerization of other vinyl monomers, which shows highly preserved Br chain-end functionality in the synthesized polymers. Moreover, the polymerization can be conducted under air atmosphere as most photocatalysts need anaerobic condition, which may give inspiration of further application of this kind of photocatalyst. 相似文献
8.
Yaoli Wang Yan Liang Huixiang Sheng Jin Wang Junjie Wang Shunhao He Mengdan Guan Yaqi Chen Prof. Gang Lu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(2):e202103709
Surface plasmon can trigger or accelerate many photochemical reactions, especially useful in energy and environmental industries. Recently, molecular adsorption has proven effective in modulating plasmon-mediated photochemistry, however the realized chemical reactions are limited and the underlying mechanism is still unclear. Herein, by using in situ dark-field optical microscopy, the plasmon-mediated oxidative etching of silver nanoparticles (Ag NPs), a typical hot-hole-driven reaction, is monitored continuously and quantitatively. The presence of thiol or thiophenol molecules is found essential in the silver oxidation. In addition, the rate of silver oxidation is modulated by the choice of different thiol or thiophenol molecules. Compared with the molecules having electron donating groups, the ones having electron accepting groups accelerate the silver oxidation dramatically. The thiol/thiophenol modulation is attributed to the modulation of the charge separation between the Ag NPs and the adsorbed thiol or thiophenol molecules. This work demonstrates the great potential of molecular adsorption in modulating the plasmon-mediated photochemistry, which will pave a new way for developing highly efficient plasmonic photocatalysts. 相似文献
9.
Nonlinear Dynamics - As a simplified model of structures of many kinds, the Euler Bernoulli beam has proved useful for studying vibration suppression. In order to meet engineering design... 相似文献
10.
Zhongxian Fan Jiaen Xie Dr. Tumpa Sadhukhan Chao Liang Can Huang Wenqing Li Tingxuan Li Dr. Pingyu Zhang Dr. Samya Banerjee Dr. Krishnan Raghavachari Dr. Huaiyi Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(3):e202103346
Four photo-catalysts of the general formula [Ir(CO6/ppy)2(L)]Cl where CO6=coumarin 6 ( Ir1 – Ir3 ), ppy=2-phenylpyridine ( Ir4 ), L=4′-(3,5-di-tert-butylphenyl)-2,2′ : 6′,2′′-terpyridine ( Ir1 ), 4′-(3,5-bis(trifluoromethyl)phenyl)-2,2′ : 6′,2′′-terpyridine ( Ir2 and Ir4 ), and 4-([2,2′ : 6′,2′′-terpyridin]-4′-yl)-N,N-dimethylaniline ( Ir3 ) were synthesized and characterized. These photostable photo-catalysts ( Ir1 – Ir3 ) showed strong visible light absorption between 400–550 nm. Upon light irradiation (465 and 525 nm), Ir1 – Ir3 generated singlet oxygen and induced rapidly photo-catalytic oxidation of cellular coenzymes NAD(P)H. Ir1 – Ir3 showed time-dependent cellular uptake with excellent intracellular retention efficiency. Upon green light irradiation (525 nm), Ir2 provided a much higher photo-index (PI=793) than the clinically used photosensitizer, 5-aminolevulinicacid (5-ALA, PI>30) against HeLa cancer cells. The observed necro-apoptotic anticancer activity of Ir2 was due to the Ir2 triggered photo-induced intracellular redox imbalance (by NAD(P)H oxidation and ROS generation) and change in the mitochondrial membrane potential. Remarkably, Ir2 showed in vivo photo-induced catalytic anticancer activity in mouse models. 相似文献