全文获取类型
收费全文 | 141篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
化学 | 104篇 |
晶体学 | 2篇 |
力学 | 2篇 |
数学 | 9篇 |
物理学 | 29篇 |
出版年
2022年 | 1篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 9篇 |
2018年 | 6篇 |
2017年 | 8篇 |
2016年 | 14篇 |
2015年 | 4篇 |
2014年 | 13篇 |
2013年 | 19篇 |
2012年 | 9篇 |
2011年 | 8篇 |
2010年 | 8篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 1篇 |
2005年 | 5篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有146条查询结果,搜索用时 234 毫秒
91.
A series of 2-(thiazol-2-yl)-4,5-dihydropyridazin-3(2H)-one derivatives were synthesized by one-pot multicomponent cyclocondensation of ketoacid, thiosemicarbazide, and phenacyl bromide using catalytical amount of KSF in EtOH under reflux. The straightforward synthesis, presence of two important class of heterocyclic rings in the individual molecule, easy workup of the products, rapid reaction, mild conditions, and good to excellent yields are notable features of this protocol.
[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
92.
Betamethasone sodium phosphate (BMNaP) has been employed as an electroactive material in the design of an ion-selective electrode (ISE). The electrode incorporates PVC membrane with betamethasone sodium phosphate-lidocaine ion pair complex. The influences of membrane composition, temperature, pH of the test solution, and the interfering ions on the electrode performance were investigated. The sensor exhibits a Nernstian response for betamethasone sodium phosphate ions over a relatively wide concentration range (1.0 × 10?1 to 1.0 × 10?5 M) with a slope of 28.4 ± 0.9 mV per decade at 25°C. It can be used in the pH range 4.0–10.0. The isothermal temperature coefficient of this electrode amounted to ?0.0008 V/°C. The membrane sensor was successfully applied to the determination of betamethasone sodium phosphate in pharmaceutical products. 相似文献
93.
The ionic liquid 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was immobilized on superparamagnetic Fe3O4 nanoparticles (IL-MNPs) and used as an efficient heterogeneous catalyst for the one-pot synthesis of 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions using microwave irradiation. The reactions in conventional heating conditions were compared with the microwave-assisted reactions. The combined merits of microwave irradiation and immobilized ionic liquid on superparamagnetic nanoparticles make the four-component condensation with safe operation, low pollution, and rapid access to products and simple work-up. 相似文献
94.
X. Liu E.K. Akdogan A. Safari R.E. Riman 《Applied Physics A: Materials Science & Processing》2005,81(3):531-537
Mechanical activation was successfully used to synthesize nanostructured phase-pure Pb(Zr0.7Ti0.3)O3 (PZT) powders. Lead–zirconium–titanium (PbZrTi) hydrous oxide precursor, synthesized from chemical co-precipitation, was mechanically activated in a NaCl matrix. The synthesized PZT particles were characterized by using X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, laser-light diffraction, and nitrogen adsorption. Thermogravimetric analysis and differential thermal analysis were used to monitor dehydration and phase transformation of PbZrTi hydrous oxide precursor during mechanical activation. The best mechanical activation conditions corresponded to mechanically activating PbZrTi hydrous oxide precursor in a NaCl matrix with a NaCl/precursor weight ratio of 4:1 for 8 h. These conditions resulted in a dispersible phase-pure PZT powder with a median secondary-particle size of ∼110 nm. The properties of PZT 70/30 from mechanically activated powder, as measured on discs sintered at 1150 °C for 2 h, were found to be in close conformity to those obtained by a conventional mixed oxide solid state reaction route. PACS 81.07.Wx; 77.84.Dy; 81.20.Ev 相似文献
95.
A. Mobinikhaledi N. Foroughifar J. Alipour Safari T. Mosleh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2329-2335
3-Oxo-2-[(Z)-1-phenylmethylidene]-5H-[1,3]thiazolo[3,2-a] pyrimidine derivatives 2a–f were synthesized by the reaction of an appropriate 3,4-dihydro-2(H)-pyrimidone 1 , chloroacetic acid, sodium acetate and benzaldehyde. Reaction of 1 with acetic anhydride under heating afforded only 3-N-acetylated 3,4-dihydro-2(H)-pyrimidines 3a–f . The yields of the products after recrystallization from ethanol were of the order of 60–92 %. IR, 1 H NMR spectroscopy, and elemental analysis were used for the identification of these compounds. 相似文献
96.
A fast, general, environmentally friendly, and facile method for preparation of 5, 5-disubstituted hydantoins from the reaction between ketone (or aldehyde) derivatives with KCN and ammonium carbonate under microwave irradiation is presented. The microwaves remarkably accelerated this reaction, the reaction times decreased dramatically, the reaction conditions were milder, and the yields were also greater. Also a comparative study of microwave versus classical conditions has been done. All the products were characterized by infrared, NMR, and CHN analysis, and their melting points are identical to those of the known compounds reported in the literature. This method might be useful in the future for the preparation of similar derivatives. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resources: Full experimental and spectral details.] 相似文献
97.
Estimation of thermal lensing effect in the high-power end-pumped direct-cut crystal lasers 总被引:1,自引:0,他引:1
At this working, analytical (with Gaussian pump beam profile) and numerical FEM (with super-Gaussian pump beam profile) methods were compared for estimation of thermal lensing effect in the diode-end-pumped solid-state laser rods. These results were applied to the design and realization of a direct-cut (i.e., cut in right-angle ) crystal Nd:YVO4 laser. The results showed that for such crystal (direct-cut), two methods obtained almost the same results, but slightly different from experimental results. However, estimation of thermal lensing effect led to realization of a diode-end-pumped Nd:YVO4 cw high-power laser with good optical quality. 相似文献
98.
Sedigheh Safari Alireza Zomorodipour Nour Amirmozaffari Morteza Daliri Choopari 《Applied biochemistry and biotechnology》2009,159(2):404-414
Hemophilia B is an X-linked recessive bleeding disorder caused by deficiency or malfunctioning of human coagulation factor
IX (hFIX). Hemophilia B patients are treated at present by infusion of plasma derived hFIX which is not always efficient,
because development of anti-hFIX antibodies (alloantibodies) in some cases inhibits the activity of the infused hFIX. The
hFIX alloantibodies are directed against γ-carboxyglutamic acid residues (Gla-domain) or protease domain in hFIX light chain.
An epitope-containing fragment of hFIX light-chain was expressed in a T7-based Escherichia coli expression system and after purification, it was used for the immunization of rabbit to develop specific antibodies anti-hFIX.
The plasma, derived from the immunized rabbit, was shown to be able to detect the normal hFIX, which indicates for the presence
of a specific anti-hFIX antibody and supporting that a bacterially expressed hFIX subfragment might be able to neutralize
the alloantibodies. Considering the importance of hFIX and its related investigations, both the produced hFIX antigen and
its corresponding antibody will play important roles for experiments dealing with the production of hFIX and studies involved
in the neutralization of the hFIX inhibitors in hFIX-related disorders and other clinical applications. 相似文献
99.
Hashem Shahroosvand Nasser Safari Ezeddin Mohajerani 《Journal of the Iranian Chemical Society》2014,11(4):1173-1182
UV lamp, filtered halogen lamp (at 425 nm) and Green laser (532 nm) experiments on a series of meso-substituted tetra phenyl porphyrin, TPP, bearing methoxy peripheral groups together with a metal derivate of 3,4 dimethoxy TPP were lead to different protonation and aggregation structures. Properties of irradiated porphyrins were investigated using their absorption and emission spectra in dichloromethane solution. The results show that the optical properties of the TPP derivates depend on light irradiation source, which shows the tuning of the absorption and emission spectra of the TPP derivates. From the dynamic light scattering measurements, the size distribution of samples was estimated about 5–15 nm in solvent after irradiation. Atomic force microscopy images of deposited porphyrins on the glass surface were shown average particle size between 10 and 30 nm. Particularly, self-assembly of the porphyrin derivates was also observed when green laser was used. We suggest that the irradiation source plays an important role in the controlling of size and morphology of products, and we propose a self-organization model to explain the formation of the porphyrin nanostructures. 相似文献
100.