全文获取类型
收费全文 | 1566篇 |
免费 | 72篇 |
国内免费 | 15篇 |
专业分类
化学 | 927篇 |
晶体学 | 17篇 |
力学 | 35篇 |
数学 | 379篇 |
物理学 | 295篇 |
出版年
2024年 | 3篇 |
2023年 | 13篇 |
2022年 | 36篇 |
2021年 | 45篇 |
2020年 | 32篇 |
2019年 | 44篇 |
2018年 | 42篇 |
2017年 | 52篇 |
2016年 | 60篇 |
2015年 | 43篇 |
2014年 | 97篇 |
2013年 | 143篇 |
2012年 | 110篇 |
2011年 | 97篇 |
2010年 | 84篇 |
2009年 | 66篇 |
2008年 | 100篇 |
2007年 | 81篇 |
2006年 | 83篇 |
2005年 | 58篇 |
2004年 | 63篇 |
2003年 | 51篇 |
2002年 | 41篇 |
2001年 | 19篇 |
2000年 | 19篇 |
1999年 | 19篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 16篇 |
1981年 | 1篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有1653条查询结果,搜索用时 187 毫秒
991.
Mujahid Abbas Safeer Hussain Khan Abdul Rahim Khan Ravi P. Agarwal 《Applied Mathematics Letters》2011,24(2):97-102
In this paper, we introduce a new one-step iterative process to approximate common fixed points of two multivalued nonexpansive mappings in a real uniformly convex Banach space. We establish weak and strong convergence theorems for the proposed process under some basic boundary conditions. 相似文献
992.
Srinivas Anga Mitali Paul Kishor Naktode Ravi K. Kottalanka Prof. Dr. Tarun K. Panda 《无机化学与普通化学杂志》2012,638(9):1311-1315
The cobalt(II) complex [CoCl2(2, 6‐iPrC6H3‐BIAO)]2 ( 1 ) of rigid unsymmetrical imine, carbonyl mixed ligand [N‐(2, 6‐diisopropylphenyl)‐imino]acenapthenone] (2, 6‐iPrC6H3‐BIAO) ( L1 ) can be achieved by the reaction of CoCl2 and neutral [N‐(2, 6‐diisopropylphenyl)‐imino]acenapthenone] ligand. When ligand L1 reacted with CuCl in dichloromethane solution, only nitrogen coordinated copper complex [CuCl(2, 6‐iPrC6H3‐BIAO)] ( 2 ) was obtained. In the solid‐state structure, compound 1 is dimeric through the chelating two μ2 chlorine atoms and each cobalt atom adopts either a distorted trigonal bipyramidal or a distorted square pyramidal arrangement. In contrast, the molecular structure of compound 2 reveals that copper is coordinated by imino nitrogen and adopts a linear arrangement around the central metal atom. The crystal structure of the rigid bidentate mixed nitrogen and oxygen ligand (2, 6‐iPrC6H3‐BIAO) ( L1 ) is also reported. 相似文献
993.
994.
995.
Pushpakumar K. Varalakshmi M. Sankar A. Uma Ravi Naidu Reddi Mohan Umamahesh K. Reddy D. Venkataramana Raju C. Naga 《Russian Journal of Organic Chemistry》2022,58(4):612-618
Russian Journal of Organic Chemistry - A series of new 1,1′-(1,4-phenylene)diurea derivatives were synthesized by reacting 1,4-diisocyanatobenzene with various biologically... 相似文献
996.
Niklas Reinfandt Nadine Michenfelder Dr. Christoph Schoo Dr. Ravi Yadav Stephan Reichl Prof. Sergey N. Konchenko Prof. Dr. Andreas N. Unterreiner Prof. Dr. Manfred Scheer Prof. Dr. Peter W. Roesky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(29):7862-7871
Reduction chemistry induced by divalent lanthanides has been primarily focused on samarium so far. In light of the rich physical properties of the lanthanides, this limitation to one element is a drawback. Since molecular divalent compounds of almost all lanthanides have been available for some time, we used one known and two new non-classical reducing agents of the early lanthanides to establish a sophisticated reduction chemistry. As a result, six new d/f-polyphosphides or d/f-polyarsenides, [K(18-crown-6)] [Cp′′2Ln(E5)FeCp*] (Ln=La, Ce, Nd; E=P, As) were obtained. Their reactivity was studied by activation of P4, resulting in a selective expansion of the P5 rings. The obtained compounds [K(18-crown-6)] [Cp′′2Ln(P7)FeCp*] (Ln=La, Nd) are the first examples of an activation of P4 by a f-element-polypnictide complex. Additionally, the first systematic femtosecond (fs)-spectroscopy investigations of d/f-polypnictides are presented to showcase the advantages of having access to a broader series of lanthanide compounds. 相似文献
997.
Mathan Kumar Shanmugaiah Kesavan Mokkandi Palsamy Ravi Lokesh Indra Gandhi N. Liviu Mitu Rajesh Jegathalaprathaban Rajagopal Gurusamy 《应用有机金属化学》2019,33(3)
Among the bio‐metals, copper derivatives of O, N, S donor salicylaldehyde thiosemicarbazones have been obtained large interest due to their potential biological applications. Multisubstituted thiosemicarbazone ligand HL derived, new ternary Cu (II) complexes of [Cu(L)(bpy)] ( 1 ) and [Cu(L)(phen)] ( 2 ) (where, bpy is 2,2′‐bipyridine and phen is 1,10‐phenanthroline) have been synthesized and characterized using different physico‐chemical techniques. Complexes 1 and 2 are structurally characterized by single crystal X‐ray diffraction analysis, which reveals the trigonal bipyramidal distorted square based pyramid geometry of both the complexes 1 and 2 with ONS‐donor thiosemicarbazone bonded at the upper plane. The ground state electronic structures of complexes 1 and 2 have been investigated by using DFT/B3LYP theoretical evaluation with 6‐31G (d,p) and LANL2DZ basis set. The affinity towards DNA and human serum albumin has been evaluated using computational docking analysis and complex 2 exposes significant binding ability towards DNA and human serum albumin, because of its immense hydrophobicity. Consequently, complex 2 have higher antimicrobial in addition to the cytotoxic activity than complex 1 and free ligand HL under visible light. Along with, their apoptosis pathway of cytotoxicity has been evaluated by fluorescent microscopic analysis using acridine orange/ethidium bromide (AO/EB) stains. From these preliminary investigations, we believe that complex 2 can play a role as a more robust pharmacological agent. 相似文献
998.
Sakram B. Rambabu S. Ashok K. Sonyanaik B. Ravi D. 《Russian Journal of General Chemistry》2016,86(12):2737-2743
Russian Journal of General Chemistry - A simple and high yielding method for synthesized benzothiazoles and benzimidazole in water under micro wave irradiation by the reaction of 2-amino thiophenol... 相似文献
999.
A series of novel α‐aminophosphonates have been prepared by one‐pot three‐component condensation in the presence of a zinc acetate (Zn(OAc)2•2H2O) catalyst at 50°C under solvent‐free conditions with excellent yields. The major advantages of the present method are high yields, a short reaction time, and solvent‐free reaction conditions. Their antimicrobial activity was evaluated, and some of them showed significant activity. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:160–165, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20765 相似文献
1000.
Rajiv Kumar Ashok K. Tiwari Uttara Chaturvedi G. Ravi Kumar Aditya P. Sahoo R. S. Rajmani Lovleen Saxena Shikha Saxena Sangeeta Tiwari Sudesh Kumar 《Applied biochemistry and biotechnology》2012,167(7):2005-2022
Cancer is one of the killer diseases in humans and needs alternate curative measures despite recent improvement in modern treatment modalities. Oncolytic virotherapy seems to be a promising nonconventional way to treat cancers. Newcastle disease virus (NDV), a poultry virus, is nonpathogenic to human and domestic animals and has a long history of being used in oncotherapy research in several preclinical studies. The ability of NDV to successfully infect and destroy cancer cells is dependent on the strain and the pathotype of the virus. Adaptation of viruses to heterologous hosts without losing its replicative and oncolytic potential is prerequisite for use as cancer virotherapeutics. In the present study, velogenic NDV was adapted for replication in HeLa cells, and its cytotoxic potential was evaluated by observing morphological, biochemical, and nuclear landmarks of apoptosis. Our results indicated that the NDV-induced apoptosis in HeLa cells was dependent on upregulation of TNF-related apoptosis-inducing ligand (TRAIL) and caspases activation. Different determinants of apoptosis evaluated in the present study indicated that this strain could be a promising candidate for cancer therapy in future. 相似文献