全文获取类型
收费全文 | 8800篇 |
免费 | 1546篇 |
国内免费 | 1126篇 |
专业分类
化学 | 6490篇 |
晶体学 | 210篇 |
力学 | 480篇 |
综合类 | 99篇 |
数学 | 927篇 |
物理学 | 3266篇 |
出版年
2024年 | 21篇 |
2023年 | 199篇 |
2022年 | 451篇 |
2021年 | 394篇 |
2020年 | 474篇 |
2019年 | 514篇 |
2018年 | 434篇 |
2017年 | 425篇 |
2016年 | 550篇 |
2015年 | 568篇 |
2014年 | 635篇 |
2013年 | 833篇 |
2012年 | 941篇 |
2011年 | 882篇 |
2010年 | 657篇 |
2009年 | 609篇 |
2008年 | 602篇 |
2007年 | 484篇 |
2006年 | 365篇 |
2005年 | 306篇 |
2004年 | 234篇 |
2003年 | 164篇 |
2002年 | 153篇 |
2001年 | 110篇 |
2000年 | 77篇 |
1999年 | 79篇 |
1998年 | 39篇 |
1997年 | 44篇 |
1996年 | 49篇 |
1995年 | 49篇 |
1994年 | 20篇 |
1993年 | 25篇 |
1992年 | 12篇 |
1991年 | 15篇 |
1990年 | 17篇 |
1989年 | 9篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 9篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1980年 | 4篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
文章合成了Lu(NO3)3(C2H5O2N)4.H2O,用红外和元素分析对其进行了表征。用高精度全自动绝热量热仪,测定了该配合物80-382 K温区的热容, 利用实验热容数据, 根据热容与焓、熵的热力学关系, 求出了配合物85-350 K温区内每隔5 K相对于298.15K的标准热力学函数(HT - H298.15)m和(ST - S298.15)m.在80-350 K温度区间内,配合物的热容随温度升高而增大,没有相转移点和热力学吸收峰的出现,该配合物在此温度区间内是稳定存在的。 相似文献
992.
993.
Fei Wang Yasukazu Kobayashi Yuxin Li Yao Wang Dezheng Wang 《Research on Chemical Intermediates》2015,41(12):9561-9573
With the calorimetric (adsorption heat versus coverage) curve also measured together with the adsorption isotherm, the simultaneous use of both curves showed that there were two phases of adsorption in the adsorption of methanol, dimethyl ether, ethene and propane in SAPO-34. The dual-site Langmuir equation gave good fits to the adsorption data to support the interpretation that a second (type 2) adsorption phase occurred in the high-pressure region in addition to a first (type 1) adsorption phase on the acid sites at lower pressures. Adsorption experiments and calculations using binary gas mixtures showed that due to the existence of two types of adsorption, the multicomponent Langmuir isotherm equation (Langmuir competitive adsorption model) calculated incorrect surface concentrations when the concentrations were high. In contrast, the ideal adsorbed solution theory (IAST) calculated correct surface concentrations in the adsorption of mixtures. 相似文献
994.
Research on Chemical Intermediates - The electronic parameters of two azole molecules, namely benzoxazole (BOX) and benzothiazole (BTH), have been studied using DFT/B3LYP, MP2, and HF methods with... 相似文献
995.
High capacity and cycling stability of poly(diaminoanthraquinone) as an organic cathode for rechargeable lithium batteries 下载免费PDF全文
Yi Fei Shen Ding Ding Yuan Xin Ping Ai Han Xi Yang Min Zhou 《Journal of Polymer Science.Polymer Physics》2015,53(4):235-238
Poly(1,5‐diaminoanthraquinone) is synthesized by oxidative polymerization of diaminoanthraquinone monomers and investigated as an organic host for Li‐storage reaction. Benefiting from its high density of redox‐active, Li+‐associable benzoquinone groups attached to conducting polyaniline backbones, this polymer undergoes its cathodic reaction predominately through Li+‐insertion/extraction processes, delivering a very high reversible capacity of 285 mAh g?1. In addition, the PDAQ polymer cathode exhibits an excellent rate capability (125 mAh g?1 at 800 mA g?1) and a considerable cyclability with a capacity retention of ~160 mAh g?1 over 200 cycles, possibly serving as a sustainable, high capacity Li+ host cathode for Li‐ion batteries. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 235–238 相似文献
996.
Ai‐Hua Zhou Fei Pan Dr. Chunyin Zhu Prof. Dr. Long‐Wu Ye 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(29):10278-10288
Fluorenes are a commonly encountered structural motif in materials science, pharmaceutical chemistry, and organic synthesis. Among various strategies towards the synthesis of this unique structure, transition metal‐catalyzed functionalization has emerged as one of the most efficient methods. This Minireview presents an overview of the recent advances in this emerging area by highlighting the reactions’ specificity and applicability and, where possible, provides a mechanistic rationale. 相似文献
997.
Fei Wang Xueqian Wang Ping Ning Xuli Jing Yixing Ma Ping Wang Wei Chen 《Adsorption》2015,21(5):401-408
A series of adsorbents were studied for removal efficiency of carbon disulfide (CS2) under micro-oxygen conditions. It was found that activated carbon modified by Cu and cobalt sulfonated phthalocyanine (CoSPc) denoted as ACCu–CoSPc showed significantly enhanced adsorption ability. Reaction temperature was found to be a key factor for adsorption, and 20 °C seems to be optimal for CS2 removal. Samples were analyzed by N2-BET, XRD, XPS, SEM–EDS and CO2-TPD. The characterization results demonstrated that large quantities of SO4 2? anions were formed and adsorbed in the reaction process. SO2, CS2 and COS were detected in the effluent gas generated from the temperature programmed desorption of ACCu–CoSPc–CS2. Therefore, it can be concluded that ACCu–CoSPc most likely acted as a catalyst in the adsorption/oxidation process on the surface of the impregnated sample. The generated sulfide and sulfur oxide can cover the active sites of adsorbents, resulting in pronounced reduction of adsorbent activity. Finally, the exhausted ACCu–CoSPc can be regenerated by thermal desorption. 相似文献
998.
999.
1000.