全文获取类型
收费全文 | 746篇 |
免费 | 45篇 |
国内免费 | 14篇 |
专业分类
化学 | 480篇 |
晶体学 | 6篇 |
力学 | 42篇 |
数学 | 59篇 |
物理学 | 218篇 |
出版年
2024年 | 2篇 |
2023年 | 10篇 |
2022年 | 21篇 |
2021年 | 31篇 |
2020年 | 38篇 |
2019年 | 29篇 |
2018年 | 42篇 |
2017年 | 47篇 |
2016年 | 44篇 |
2015年 | 30篇 |
2014年 | 48篇 |
2013年 | 94篇 |
2012年 | 62篇 |
2011年 | 45篇 |
2010年 | 24篇 |
2009年 | 31篇 |
2008年 | 31篇 |
2007年 | 24篇 |
2006年 | 13篇 |
2005年 | 18篇 |
2004年 | 14篇 |
2003年 | 16篇 |
2002年 | 12篇 |
2001年 | 11篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有805条查询结果,搜索用时 46 毫秒
151.
Majid M. Heravi Dariush Ajami Mahmood Tajbakhsh Mitra Ghassemzadeh 《Monatshefte für Chemie / Chemical Monthly》2000,1(2):1109-1113
A convenient method for the direct conversion of oximes to carbonyl compounds upon treatment with clay supported BTSC under classical heating as well as microwave irradiation in a solvent-free system is described. 相似文献
152.
In the present study, plant‐mediated synthesis of iron oxide nanoparticles (IONPs) using leaves extract of Rhamnus virgata (Roxb.) as a potential stabilizing, reducing and chelating agent is reported. The biogenic IONPs are extensively characterized for their physical and biological properties. The morphology, structure and physicochemical properties of biogenic IONPs were characterized using ultraviolet spectroscopy, X‐ray diffraction, Fourier transform‐infrared analysis, scanning electron microscopy, energy‐dispersive spectroscopy, transmission electron microscopy, Raman spectroscopy and dynamic light scattering. The Scherrer equation deduced a mean crystallite size of ~20 nm for IONPs. Detailed in vitro biological activities revealed significant therapeutic potentials for IONPs. Potential antibacterial and antifungal activities are reported for IONPs. Bioinspired IONPs have shown potential results against HepG2 cells (IC50: 13.47 μg/ml). Dose‐dependent cytotoxicity assays were revealed against Leishmania tropica (KMH23) promastigotes (IC50: 8.08 μg/ml) and amastigotes (IC50: 20.82 μg/ml) using different concentrations of IONPs (1–200 μg/ml). The cytotoxic activity was also studied using brine shrimps, and their IC50 value was calculated as 32.41 μg/ml. Significant antioxidant [TAC (51.4%), DPPH (79.4%) and total reducing power (62%)], protein kinase and alpha amylase inhibition assays were revealed. The biocompatibility assays using red blood cells (> 200 μg/ml) and macrophages (> 200 μg/ml) confirmed the biosafe nature of IONPs. In conclusion, bioinspired IONPs have shown potential biological applications and should be subjected to further research work to develop their nano‐pharmacological relevance in biomedical applications. 相似文献
153.
Mahmood Tajbakhsh Majid M. Heravi Farajollah Mohanazadeh Siavosh Sarabi Mitra Ghassemzadeh 《Monatshefte für Chemie / Chemical Monthly》2001,132(10):1229-1231
Summary. N-Methylpiperidinium chlorochromate adsorbed on alumina was found to be an efficient and selective reagent for the mild oxidative
cleavage of oximes.
Received March 1, 2001. Accepted March 22, 2001 相似文献
154.
M. F. Mahmood 《Optics & Laser Technology》2001,33(6):379
A variational technique has been applied to the evolution of optical solitons in a nonlinear dispersive lossy fibre. An analytical model has been developed to describe the interaction of two co-propagating orthogonally polarized optical pulses in a lossy fibre, governed by a pair of coupled nonlinear Schroedinger equations, and the threshold amplitude at which the solitons form a bound state has been obtained. 相似文献
155.
Mahmood Tajbakhsh Majid M. Heravi Farajollah Mohanazadeh Siavosh Sarabi Mitra Ghassemzadeh 《Monatshefte für Chemie / Chemical Monthly》2001,45(6):1229-1231
N-Methylpiperidinium chlorochromate adsorbed on alumina was found to be an efficient and selective reagent for the mild oxidative
cleavage of oximes. 相似文献
156.
Riyadh Zendin Mawlud Sangar S. Ahmed Sobhan Mortazavi-Derazkola Omid Amiri Zahra Salehi Peshawa H. Mahmood 《应用有机金属化学》2020,34(8):e5652
In this study, dendrite-like Sn nanocomposites were achieved by engineering the synthesis parameters. The dendritic Sn nanostructures show higher photocatalytic activity compared to nanoplate Sn and hierarchical Sn nanostructures. Flower-like Sn–Cu and cactus-like Sn–Ag nanostructures were prepared to improve the photocatalytic activity of Sn nanostructures. Adding Cu and Ag improved the photocatalytic activity of Sn by 24% and 46%, respectively. The photodegradation results revealed that the cactus-like Sn–Ag has a high degradation rate (5.3 × 10−4 mmol L−1 min−1) compared to the Sn nanostructures (2.9 × 10−4 mmol L−1 min−1). This work provides new insight into the design of highly efficient photocatalysts by engineering the morphology. 相似文献
157.
Mohammad S. Asgari Behnam Tahmasebi Somayeh Mojtabavi Mohammad A. Faramarzi Rahmatollah Rahimi Parviz R. Ranjbar Mahmood Biglar Bagher Larijani Hossein Rastegar Maryam Mohammadi-Khanaposhtani Mohammad Mahdavi 《Journal of heterocyclic chemistry》2020,57(12):4348-4357
A new series of acridine-9-carboxamide-1,2,3-triazole derivatives 7a-m were designed, synthesized, and evaluated as novel α-glucosidase inhibitors. Acridine-9-carboxamide-1,2,3-triazole scaffold has been designed by combination of effective moieties from potent α-glucosidase inhibitors. Most of the synthesized compounds were more potent than standard inhibitor acarbose. Among the title compounds, the most potent compounds were compounds 7j , 7k , and 7a with IC50 values of 120.2 ± 1.0, 151.1 ± 1.4, and 157.6 ± 1.6 μM, respectively (IC50 value of acarbose = 750.0 ± 10.0 μM). Docking study of the most potent compounds demonstrated that these compounds formed stable complexes with α-glucosidase active site. Anti-α-amylase assay of compounds 7j , 7k , and 7a was performed and no activity was observed. in vitro cytotoxicity assay of the latter compounds revealed that these compounds were not cytotoxic toward human normal (HDF) and cancer (MCF-7) cell lines. ADME and toxicity prediction of compounds 7j , 7k , and 7a were also performed. 相似文献
158.
During the life period of Small and Medium Enterprises (SMEs) in incubators they need some training programs to acquire the required knowledge in order to survive and succeed in the business environment. This paper presents a heuristic method based on an optimization model to schedule these programs at the most suitable times. Based on the proposed heuristic, each training program is implemented in a suitable time by considering the SMEs’ requirements and some other logical constraints. The proposed heuristic is described in detail, and its implementation is demonstrated via a real-life numerical example. The numerical results of the heuristic are compared with other methods. 相似文献
159.
Meshkani Fereshteh Golesorkh Sayyede Fateme Rezaei Mehran Andache Mahmood 《Research on Chemical Intermediates》2017,43(1):545-559
Research on Chemical Intermediates - Mesoporous MgAl2O4 nanopowders were synthesized via the homogenous precipitation method and employed as a support for Ni catalysts in the dry reforming... 相似文献
160.
In this article, we present a method to synthesize strong nonlinear components used in encryption algorithms. The proposed nonlinear component assists in transforming the intelligible message or plaintext into an enciphered format by the use of Lorenz and Rössler chaotic systems. A substitution box is generated that uses initial conditions, utilize multi-chaotic parameter values, and employ numerical simulations. 相似文献