全文获取类型
收费全文 | 468403篇 |
免费 | 4554篇 |
国内免费 | 1302篇 |
专业分类
化学 | 236046篇 |
晶体学 | 7473篇 |
力学 | 23621篇 |
综合类 | 17篇 |
数学 | 56781篇 |
物理学 | 150321篇 |
出版年
2021年 | 4295篇 |
2020年 | 4562篇 |
2019年 | 5300篇 |
2018年 | 7403篇 |
2017年 | 7591篇 |
2016年 | 10327篇 |
2015年 | 5666篇 |
2014年 | 9732篇 |
2013年 | 21701篇 |
2012年 | 16841篇 |
2011年 | 20127篇 |
2010年 | 15226篇 |
2009年 | 15315篇 |
2008年 | 18407篇 |
2007年 | 18275篇 |
2006年 | 16651篇 |
2005年 | 14570篇 |
2004年 | 13649篇 |
2003年 | 12174篇 |
2002年 | 12193篇 |
2001年 | 14155篇 |
2000年 | 10482篇 |
1999年 | 8095篇 |
1998年 | 6825篇 |
1997年 | 6731篇 |
1996年 | 6229篇 |
1995年 | 5455篇 |
1994年 | 5503篇 |
1993年 | 5281篇 |
1992年 | 5898篇 |
1991年 | 6189篇 |
1990年 | 5836篇 |
1989年 | 5852篇 |
1988年 | 5557篇 |
1987年 | 5691篇 |
1986年 | 5345篇 |
1985年 | 6794篇 |
1984年 | 6951篇 |
1983年 | 5770篇 |
1982年 | 5806篇 |
1981年 | 5586篇 |
1980年 | 5344篇 |
1979年 | 5887篇 |
1978年 | 5833篇 |
1977年 | 6015篇 |
1976年 | 5990篇 |
1975年 | 5654篇 |
1974年 | 5545篇 |
1973年 | 5659篇 |
1972年 | 4142篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
The Effect of the Spacer of Bis(biurea) Ligands on the Structure of A2L3‐type (A=anion) Phosphate Complexes
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Prof. Biao Wu Dr. Shaoguang Li Prof. Yibo Lei Prof. Huaiming Hu Dr. Nader de Sousa Amadeu Prof. Dr. Christoph Janiak Dr. Jennifer S. Mathieson Dr. De‐Liang Long Prof. Leroy Cronin Prof. Xiao‐Juan Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2588-2593
By tuning the length and rigidity of the spacer of bis(biurea) ligands L, three structural motifs of the A2L3 complexes (A represents anion, here orthophosphate PO43?), namely helicate, mesocate, and mono‐bridged motif, have been assembled by coordination of the ligand to phosphate anion. Crystal structure analysis indicated that in the three complexes, each of the phosphate ions is coordinated by twelve hydrogen bonds from six surrounding urea groups. The anion coordination properties in solution have also been studied. The results further demonstrate the coordination behavior of phosphate ion, which shows strong tendency for coordination saturation and geometrical preference, thus allowing for the assembly of novel anion coordination‐based structures as in transition‐metal complexes. 相似文献
103.
Journal of Applied and Industrial Mathematics - We consider the optimization of the short wave phased antenna arrays as a quadratic programming problem. The penalty function method and the gradient... 相似文献
104.
Indermeet Kohli Taylor L. Braunberger Amanda F. Nahhas Fatima N. Mirza Mohsen Mokhtari Alexis B. Lyons Nikiforos Kollias Eduardo Ruvolo Henry W. Lim Iltefat H. Hamzavi 《Photochemistry and photobiology》2020,96(1):208-214
Human skin is exposed to visible light (VL; 400–700 nm) and long-wavelength ultraviolet A1 (UVA1) radiation (370–400 nm) after the application of organic broad-spectrum sunscreens. The biologic effects of these wavelengths have been demonstrated; however, a dose–response has not been investigated. Ten subjects with Fitzpatrick skin phototype IV-VI were enrolled. Subjects were irradiated with 2 light sources (80–480 J cm−2): one comprising VL with less than 0.5% UVA1 (VL+UVA1) and the other pure VL. Skin responses were evaluated for 2 weeks using clinical and spectroscopic assessments. 4-mm punch biopsies were obtained from nonirradiated skin and sites irradiated with 480 J cm−2 of VL+UVA1 and pure VL 24 h after irradiation. Clinical and spectroscopic assessments demonstrated a robust response at VL+UVA1 sites compared with pure VL. Histology findings demonstrated a statistically significant increase in the marker of inflammation (P < 0.05) and proliferation (P < 0.05) at the irradiated sites compared with nonirradiated control. Threshold doses of VL+UVA1 resulting in biologic responses were calculated. Results indicate that approximately 2 h of sun exposure, which equates to VL+UVA1 dose (~400 J cm−2), is capable of inducing inflammation, immediate erythema and delayed tanning. These findings reinforce the need of photoprotection beyond the UV range. 相似文献
105.
106.
107.
108.
109.
110.