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101.
102.
Phase separation behavior has been studied in aqueous solutions of partially butyralized poly(vinyl alcohol) (BuPVA) with various degrees of butyralization xBu and various molecular weights. It is found that these systems exhibit both upper and lower critical solution temperatures. The theta temperatures θLCST, evaluated by means of Shultz–Flory plots, are found to be 25.1, 23.3, and 14.4°C for BuPVAs with xBu of 7.5, 9.9, and 12.7 mol %, respectively. The unperturbed dimension 〈R20/M is evaluated as ca. 1.2 × 10?16 Å2 in the above range of xBu from viscosity measurement at θLCST. Properties of the BuPVA solutions are compared with those of other PVA copolymers.  相似文献   
103.
[reaction: see text] The TiCl(4)-catalyzed Evans-aldol reaction of optically active 3,3,3-trifluoropropanoic imide gave the non-Evans syn product stereoselectively, whereas the Reformatsky reaction of 2-bromo-3,3,3-trifluoropropanoic imide in the presence of Et(3)Al led to the Evans anti product. These new approaches enabled us to synthesize all stereoisomers of trifluoromethylated aldol products for the first time.  相似文献   
104.
Changes in the intracellular Ca2+ concentration regulate numerous cell functions and display diverse spatiotemporal dynamics, which underlie the versatility of Ca2+ in cell signaling. In many cell types, an increase in the intracellular Ca2+ concentration starts locally, propagates within the cell (Ca2+ wave) and makes oscillatory changes (Ca2+ oscillation). Studies of the intracellular Ca2+ release mechanism from the endoplasmic reticulum (ER) showed that the Ca2+ release mechanism has inherent regenerative properties, which is essential for the generation of Ca2+ waves and oscillations. Ca2+ may shuttle between the ER and mitochondria, and this appears to be important for pacemaking of Ca2+ oscillations. Importantly, Ca2+ oscillations are an efficient mechanism in regulating cell functions, having effects supra-proportional to the sum of duration of Ca2+ increase. Furthermore, Ca2+ signaling mechanism studies have led to the development of a method for specific inhibition of Ca2+ signaling, which has been used to identify hitherto unrecognized functions of Ca2+ signals.  相似文献   
105.
In laser ablation of biological tissue, tomography of the tissue surface is necessary for measurement of the crater shape and the crater depth. In this paper, we demonstrate in-situ observation of biological-tissue surface in laser ablation by optical coherence tomography (OCT). Depth of a crater of human tooth is measured by these OCT images, and then the ablation rate of 0.21 μm/pulse is determined.  相似文献   
106.
Competitive nitrations of two pairs of aromatic substrates were carried out in order to clarify the effect of several methods of mixing on the observed relative rates. The experimental results indicate that a commercially available four-jet mixer for rapid reaction could not achieve homogeneous mixing in the competitive nitration of aromatic substrates in aqueous sulfuric acid.  相似文献   
107.
A novel multi-functional vertical high shear kneader has been developed. Wet kneading of pharmaceutical powders was conducted under various blade components and operating conditions. Compression properties of wet kneaded mass was analyzed and dispersion of hinder liquid (water) among the mass was investigated by assaying tracer aqueous pigment. Pellets were produced through a dome type extrusion granulator with continuous extrusion pressure measurement device and a fluidized bed drier, and then the physical properties were measured. Quantitative relationship between the pellet's physical properties and the binder dispersion condition as well as the compression properties could be obtained. It was found that the newly developed kneader was very effective to uniformly disperse binder as well as impart high shear stress to the wet mass without generating obvious adhesion onto the vessel wall. It was also pointed out that the extrusion pressure could determine the physical strength of pellet. This method proposes a new methodology for continuous monitoring of kneading condition as well as predicting pellet's physical properties.  相似文献   
108.
A novel Hantzsch 1,4-dihydropyridine derivative could function in an organic solvent-free solution, and thus it could function in biological systems. These functions can be accomplished through regeneration of the reduced form of nicotinamine adenine dinucleotide (NADH), an essential compound for living organisms. The results obtained here demonstrate the usefulness of a water-soluble Hantzsch 1,4-dihydropyridine derivative and its wide applicability as a chemical energy source, which drives various biological processes efficiently.  相似文献   
109.
This paper examines an optimal stopping problem for a geometric Brownian motion with random jumps. It is assumed that jumps occur according to a time-homogeneous Poisson process and the proportions of these sizes are independent and identically distributed nonpositive random variables. The objective is to find an optimal stopping time of maximizing the expected discounted terminal reward which is defined as a nondecreasing power function of the stopped state. By applying the “smooth pasting technique” [1,2], we derive almost explicitly an optimal stopping rule of a threshold type and the optimal value function of the initial state. That is, we express the critical state of the optimal stopping region and the optimal value function by formulae which include only given problem parameters except an unknown to be uniquely determined by a nonlinear equation.  相似文献   
110.
Measurements have been made of F and H centre production rates in KBr doped with KI, when electron irradiated at 5°K. Significant concentrations of I reduce the production rates of both centres. In the mixed crystals complex H bands are formed and the thermal annealing behaviour of these bands has been measured.  相似文献   
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