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281.
Taha M Abdel‐Rahman 《Journal of heterocyclic chemistry》2005,42(7):1257-1265
Behaviour of 2‐(4‐oxo‐4H‐benzo[d][l,3]oxazin‐2‐yl)‐benzoic acid (1) towards nitrogen nucleophiles namely, hydrazine hydrate, in different solvents, ammonium acetate, and o‐phenylenediamine has been investigated to give aminoquinazolin‐4‐one, benzotriazepinone, spiro‐type compound, and nitrogen bridgehead compounds 3‐5 , respectively. Also, reactivity of the aminoquinazolin‐4‐one 2 towards carbon elec‐trophiles such as ethyl acetoacetate, ethyl phenylacetate, ethyl chloroacetate, and aromatic aldehydes has been discussed. Reaction of Schiff s base 8 with sulfur nucleophiles namely o‐aminothiophenol and/or thio‐glycolic acid afforded Michael type adducts. Structural assignments, of products 1‐24 have been confirmed by elemental analysis and spectral data (1H‐ and 13C ‐NMR and MS fragmentation). The bioassay indicates that some of the target compounds obtained have good selective anticancer activity. 相似文献
282.
TheBacillus subtilis alkaline protease(aprA) gene was previously cloned on a pUBHO-derivative plasmid. High levels of expression and gene stability were demonstrated
whenB. subtilis cells were grown on the laboratory medium 2XSG.B. subtilis cells harboring the multicopyaprA gene were grown on basal medium, supplemented with 1 % chicken feather as a source of energy, carbon, and nitrogen. Proteolytic
and kera-tinolytic activities were monitored throughout the cultivation time. A high level of keratinolytic activity was obtained,
and this indicates that alkaline protease is acting as a keratinase. Furthermore, considerable amounts of soluble proteins
and free amino acids were obtained as a result of the enzymatic hydrolysis of feather. Biodegradation of feather waste using
these cells represents an alternative way to improve the nutritional value of feather, since feather waste is currently utilized
on a limited basis as a dietary protein supplement for animal feedstuffs. Moreover, the release of free amino acids from feather
and the secreted keratinase enzyme would promote industries based on feather waste. 相似文献
283.
N-methyl and N-benzyl hydroxylamines were synthetically conjugated to alginic acid to produce hydroxamated derivatives with different degrees of substitution. The new polymeric materials were used to form coordinate complexes with iron(III). The hydroxamated derivatives as well as their iron complexes were characterized using infrared spectroscopy and differential scanning calorimetry.Phenobarbitone-loaded and blank beads were prepared utilizing the new iron-crosslinked hydroxamated polymers and evaluated with respect to their ability to control drug release, as well as their iron leaching properties.The iron-crosslinked polymeric composites proved capable of encapsulating the model drug and sustaining its release in the dissolution media, the release profiles were sensitive to the type and degree of substitution. 相似文献
284.
Cathodic stripping voltammetry was used to determine 5-fluorouracil (5-FU) in the presence of traces of Cu(II). It was found that the addition of 5 x 10(-9) mol dm(-3) Cu(II) to the measurement cell greatly enhanced the peak current of the adsorbed molecule. Different parameters were tested to optimize the conditions for the determination of 5-FU. The adsorbed form is reduced irreversibly. It was observed that by controlling the deposition potential, the technique could be directed to the determination of Cu(II) or the drug. The linear range was from 5 x 10(-9) to 6 x 10(-8) mol dm(-3) for 5-FU and from 6 x 10(-9) to 5 x 10(-8) mol dm(-3) for Cu(II). Detection limits of 4.6 x 10(-10) and 5 x 10(-10) mol dm(-3) were obtained for 5-FU and Cu(II), respectively. The method was applied to urine and molecules or ions which may interfere were studied. 相似文献
285.
Aziz Asim Jamshed Wasim Aziz Taha Bahaidarah Haitham M. S. Ur Rehman Khalil 《Journal of Thermal Analysis and Calorimetry》2021,143(2):1331-1343
Journal of Thermal Analysis and Calorimetry - Hybrid nanofluids are introduced as heat transfer fluids with greater surface stability, diffusion and dispersion capabilities compared to traditional... 相似文献
286.
Chromatographic investigation of an extract of the octocoral Xenia umbellata afforded two new diterpenes, xenibelatols A (1) and B (2), in addition to three known xenicane diterpenes, 7,8-oxidoisoxeniolide (3), 9-hydroxyxeniolide F (4), and florlide C, and a cadinene sesquiterpene, xenitorin A (5). The structures were elucidated through spectroscopic analysis, especially 2D NMR. 相似文献
287.
Asif Hayat Muhammad Sohail Hamid Ali T. A. Taha H. I. A. Qazi Naveed Ur Rahman Zeeshan Ajmal Abul Kalam Abdullah G. Al-Sehemi S. Wageh Mohammed A. Amin Arkom Palamanit W. I. Nawawi Emad F. Newair Yasin Orooji 《Chemical record (New York, N.Y.)》2023,23(2):e202200149
Recently, the growing demand for a renewable and sustainable fuel alternative is contingent on fuel cell technologies. Even though it is regarded as an environmentally sustainable method of generating fuel for immediate concerns, it must be enhanced to make it extraordinarily affordable, and environmentally sustainable. Hydrogen (H2) synthesis by electrochemical water splitting (ECWS) is considered one of the foremost potential prospective methods for renewable energy output and H2 society implementation. Existing massive H2 output is mostly reliant on the steaming reformation of carbon fuels that yield CO2 together with H2 and is a finite resource. ECWS is a viable, efficient, and contamination-free method for H2 evolution. Consequently, developing reliable and cost-effective technology for ECWS was a top priority for scientists around the globe. Utilizing renewable technologies to decrease total fuel utilization is crucial for H2 evolution. Capturing and transforming the fuel from the ambient through various renewable solutions for water splitting (WS) could effectively reduce the need for additional electricity. ECWS is among the foremost potential prospective methods for renewable energy output and the achievement of a H2-based economy. For the overall water splitting (OWS), several transition-metal-based polyfunctional metal catalysts for both cathode and anode have been synthesized. Furthermore, the essential to the widespread adoption of such technology is the development of reduced-price, super functional electrocatalysts to substitute those, depending on metals. Many metal-premised electrocatalysts for both the anode and cathode have been designed for the WS process. The attributes of H2 and oxygen (O2) dynamics interactions on the electrodes of water electrolysis cells and the fundamental techniques for evaluating the achievement of electrocatalysts are outlined in this paper. Special emphasis is paid to their fabrication, electrocatalytic performance, durability, and measures for enhancing their efficiency. In addition, prospective ideas on metal-based WS electrocatalysts based on existing problems are presented. It is anticipated that this review will offer a straight direction toward the engineering and construction of novel polyfunctional electrocatalysts encompassing superior efficiency in a suitable WS technique. 相似文献
288.
Invariant approach to optimal investment–consumption problem: the constant elasticity of variance (CEV) model 下载免费PDF全文
Ahmet Bakkaloglu Taha Aziz Aeeman Fatima F.M. Mahomed Chaudry Masood Khalique 《Mathematical Methods in the Applied Sciences》2017,40(5):1382-1395
The optimal investment–consumption problem under the constant elasticity of variance (CEV) model is solved using the invariant approach. Firstly, the invariance criteria for scalar linear second‐order parabolic partial differential equations in two independent variables are reviewed. The criteria is then employed to reduce the CEV model to one of the four Lie canonical forms. It is found that the invariance criteria help in transforming the original equation to the second Lie canonical form and with a proper parameter selection; the required transformation converts the original equation to the first Lie canonical form that is the heat equation. As a consequence, we find some new classes of closed‐form solutions of the CEV model for the case of reduction into heat equation and also into second Lie canonical form. The closed‐form analytical solution of the Cauchy initial value problems for the CEV model under investigation is also obtained. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
289.
Chemical preparation, X-ray single crystal diffraction, thermal analysis, electrochemical measurements, IR, Raman and UV spectroscopic investigations of a novel organic-inorganic hybrid material(C4H7N2)CdCl3(H2O)(1) were described. 1-Methylimidazolium aquapentachlorocadmate(II) crystallized in the monoclinic system with P21/n space group. Its structure provided a new interesting example of infinite inorganic layers of [CdCl3(H2O)]nn- centered by (-101) planes. The [CdCl5(H2O)]-anions were interconnected by O-H···Cl hydrogen bonds. Acidic protons of the chloride group were transferred to the organic molecule, giving the singly-protonated cations. The ability of ions to form a spontaneous three-dimensional structure through O-H···Cl and N-H···Cl hydrogen bonds was fully utilized. These hydrogen bonds induced notable vibrational effects. IR and Raman spectra were reported and discussed on the basis of group theoretical analysis and on quantum chemical density theory(DFT) calculation. The molecular HOMO-LUMO compositions and their respective energy gaps were also drawn to explain the activity of our compound. The role of the intermolecular interaction in this crystal was analyzed. The optical study was also investigated by UV-Vis absorption spectrum. Thermal analysis reveals the hydrous character of the compound. Cyclic voltammetry was studied to evaluate the spectral and structural changes accompanying electron transfer. 相似文献
290.
Anas Taha Stephanie Taha-Mehlitz Stephanie Petzold Sergey L. Achinovich Dmitry Zinovkin Bassey Enodien Md Zahidul I. Pranjol Eldar A. Nadyrov 《Molecules (Basel, Switzerland)》2022,27(3)
The aim of this study is to reveal the potential roles of apoptosis markers (Bcl2 and p53), proliferation markers (Ki-67 and CyclD1), and the neuroendocrine marker Chromogranin A as markers for the radioresistance of rectal cancer. Statistically significant differences were found in the expression of p53, Ki-67, and Chromogranin A in groups of patients with and without a favorable prognosis after radiotherapy. The survival analysis revealed that the marker of neuroendocrine differentiation, Chromogranin A, also demonstrated a high prognostic significance, indicating a poor prognosis. Markers of proliferation and apoptosis had no prognostic value for patients who received preoperative radiotherapy. Higher Chromogranin A values were predictors of poor prognosis. The results obtained from studying the Chromogranin A expression suggest that the secretion of biologically active substances by neuroendocrine cells causes an increase in tumor aggressiveness. 相似文献