全文获取类型
收费全文 | 177050篇 |
免费 | 28828篇 |
国内免费 | 23598篇 |
专业分类
化学 | 125869篇 |
晶体学 | 2375篇 |
力学 | 10721篇 |
综合类 | 1612篇 |
数学 | 23065篇 |
物理学 | 65834篇 |
出版年
2024年 | 182篇 |
2023年 | 2995篇 |
2022年 | 3986篇 |
2021年 | 5628篇 |
2020年 | 6624篇 |
2019年 | 6618篇 |
2018年 | 5929篇 |
2017年 | 5734篇 |
2016年 | 8263篇 |
2015年 | 8243篇 |
2014年 | 10174篇 |
2013年 | 13306篇 |
2012年 | 15823篇 |
2011年 | 16609篇 |
2010年 | 11918篇 |
2009年 | 11498篇 |
2008年 | 12392篇 |
2007年 | 11008篇 |
2006年 | 10516篇 |
2005年 | 8772篇 |
2004年 | 6946篇 |
2003年 | 5625篇 |
2002年 | 5696篇 |
2001年 | 4697篇 |
2000年 | 3881篇 |
1999年 | 3825篇 |
1998年 | 3047篇 |
1997年 | 2613篇 |
1996年 | 2516篇 |
1995年 | 2301篇 |
1994年 | 2071篇 |
1993年 | 1705篇 |
1992年 | 1507篇 |
1991年 | 1331篇 |
1990年 | 1132篇 |
1989年 | 874篇 |
1988年 | 661篇 |
1987年 | 554篇 |
1986年 | 538篇 |
1985年 | 452篇 |
1984年 | 280篇 |
1983年 | 248篇 |
1982年 | 193篇 |
1981年 | 138篇 |
1980年 | 86篇 |
1979年 | 54篇 |
1978年 | 29篇 |
1976年 | 27篇 |
1975年 | 27篇 |
1957年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Zhihong Zhao Bin Wang Rui Tan Wenjing Liu Minghui Zhang 《Magnetic resonance in chemistry : MRC》2022,60(4):427-433
In this study, the transverse relaxation time (T2) of activated carbon (AC) in different relative environment humidity was detected firstly by low-field nuclear magnetic resonance (LFNMR). The pore size (diameter) of AC distributions was calculated by the relationship between T2 and surface relaxation rate (ρ), where ρ was obtained by the detection of nine porous materials with known pore size. The results showed that the pore size distributions of AC calculated by ρ < 0.19 nm/ms were in good agreement with that obtained by nitrogen adsorption method and proved that LFNMR as a new detection method was feasible for characterizing AC pore size distribution. 相似文献
2.
Patrick Imrie Jianyong Jin 《Journal of polymer science. Part A, Polymer chemistry》2022,60(2):149-174
4D printing is an exciting branch of additive manufacturing. It relies on established 3D printing techniques to fabricate objects in much the same way. However, structures which fall into the 4D printed category have the ability to change with time, hence the “extra dimension.” The common perception of 4D printed objects is that of macroscopic single-material structures limited to point-to-point shape change only, in response to either heat or water. However, in the area of polymer 4D printing, recent advancements challenge this understanding. A host of new polymeric materials have been designed which display a variety of wonderful effects brought about by unconventional stimuli, and advanced additive manufacturing techniques have been developed to accommodate them. As a result, the horizons of polymer 4D printing have been broadened beyond what was initially thought possible. In this review, we showcase the many studies which evolve the very definition of polymer 4D printing, and reveal emerging areas of research integral to its advancement. 相似文献
3.
Yang T. L. Kao C. L. Kuo C. E. Yeh H. C. Li W. J. Li H. T. Chen C. Y. 《Chemistry of Natural Compounds》2022,58(5):825-827
Chemistry of Natural Compounds - A novel bibenzyl derivative, hydrangchinenin (1), was isolated from the stems of Hydrangea chinensis Maxim. (Hydrangeaceae). Its structure was determined on the... 相似文献
4.
5.
Chen Zi-Han Li Yue-Hua Qi Ming-Yu Tang Zi-Rong Xu Yi-Jun 《Research on Chemical Intermediates》2022,48(1):1-12
Research on Chemical Intermediates - Owing to the simultaneous utilization of photogenerated electrons and holes, coupling light-driven hydrogen (H2) evolution reaction (HER) and biomass-derived... 相似文献
6.
Zhang Bing Yang Jie-qin Liu Ying Hu Bin Yang Yang Zhao Li Lu Qiang 《Cellulose (London, England)》2022,29(12):6565-6578
Cellulose - Heating is essential in various biomass pre-treatments and thermal conversion processes. It is of practical significance to study the characteristics of cellulose-lignin and... 相似文献
7.
8.
Lin Yu Wu Yeyu Tan Xuecai Wu Jiawen Huang Kejing Mi Yan Ou Panpan Wei Fucun 《Journal of Solid State Electrochemistry》2022,26(4):959-971
Journal of Solid State Electrochemistry - An ultrasensitive “signal-off–on” electrochemiluminescence (ECL) biosensor is constructed based on f1-TiO2/g-C3N4/PDA for thrombin... 相似文献
9.
Guo-Xing Li Xiao-Wei Qu Lu-Wei Hao Qing Li Su Chen 《Journal of polymer science. Part A, Polymer chemistry》2022,60(11):1710-1717
From the implementation point of view, the printable magnetic Janus colloidal photonic crystals (CPCs) microspheres are highly desirable. Herein, we developed a dispensing-printing strategy for magnetic Janus CPCs display via a microfluidics-automatic printing system. Monodisperse core/shell colloidal particles and magnetic Fe3O4 nanoparticles precursor serve as inks. Based on the equilibrium of three-phase interfacial tensions, Janus structure is successfully formed, followed by UV irradiation and self-assembly of colloid particle to generate magnetic Janus CPCs microspheres. Notably, this method shows distinct superiority with highly uniform Janus CPCs structure, where the TMPTA/Fe3O4 hemisphere is in the bottom side while CPCs hemisphere is in the top side. Thus, by using Janus CPCs microspheres with two different structural colors as pixel points, a pattern with red flower and green leaf is achieved. Moreover, 1D linear Janus CPCs pattern encapsulated by hydrogel is also fabricated. Both the color and the shape can be changed under the traction of magnets, showing great potentials in flexible smart displays. We believe this work not only offers a new feasible pathway to construct magnetic Janus CPCs patterns by a dispensing-printable fashion, but also provides new opportunities for flexible and smart displays. 相似文献
10.
Dan Chen Kaixin Du Xiaochen Niu Hongwei Zhang Xue Zhang Yu Tang Jianchun Zhao 《Biomedical chromatography : BMC》2022,36(3):e5288
Amlexanox, an anti-inflammatory and anti-allergic agent, has been widely used clinically for the treatment of canker sores, asthma, and allergic rhinitis. Recently, amlexanox has received considerable attention in curing nonalcoholic fatty liver diseases and hepatitis virus infection. Herein, we first established a sensitive high-performance liquid chromatography-tandem mass spectrum (LC–MS/MS) method for the determination of amlexanox in rat plasma. Propranolol was used as the internal standard (IS). Using a simple protein precipitation method, the amlexanox and IS were separated with Capcell Pak C18 column (2.0 × 50 mm, 5 μm) and eluted with water and acetonitrile each containing 0.1% formic acid using gradient elution condition at a flow rate of 0.4 mL·min−1. Amlexanox and IS were detected by a triple quadrupole mass in multiple reactive monitoring (MRM) under the transitions of m/z 299.2 → 281.2 and m/z 259.9 → 116.1 with positive electrospray ionization, respectively. The calibration curves of amlexanox were established with the range of 50 to 2000 ng·mL−1 (r2 > 0.99). The validation method consisted of selectivity, accuracy, precision, carryover effect, matrix effect, recovery, dilution effect, and stability. The fully validated method was successfully applied to the pharmacokinetic study of amlexanox in Wistar rats. 相似文献