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排序方式: 共有4849条查询结果,搜索用时 19 毫秒
61.
薄层扫描法测定冬眠过程中刺猬活性组织酶的周期变化冯金城(天津师范大学天津300074)孙金生(天津水产研究所天津300221)1前言为了跟踪观察刺猬在冬眠过程中体内乳酸脱氢酶的周期性变化,利用薄层扫描仪测定了其相关的组织同工酶的差异。实践证明,此法简... 相似文献
62.
Tsutomu Oishi Kensoh Kagawa Minoru Fujimoto 《Journal of polymer science. Part A, Polymer chemistry》1995,33(8):1341-1352
Two types of optically active N-[N′-(α-methylbenzyl)amino/carbonyl-n-alkyl]maleimides (MBAC) were synthesized from maleic anhydride, 6-amino-n-caproic acid (or 12-amino-n-dodecanoic acid), and (R)-(+)-α-methylbenzylamine. Radical homopolymerizations of MBAC were performed in several solvents at 60 and 110°C for 24 h to give optically active polymers. Radical copolymerizations of MBAC were performed with styrene (ST) and methyl methacrylate (MMA) in dioxane at 60°C. The monomer reactivity ratios and the Alfrey-Price Q-e values were determined. Chiroptical properties of the polymers and copolymers were investigated. © 1995 John Wiley & Sons, Inc. 相似文献
63.
David M. Rogers Claire Wells Melanie Joseph Vanessa J. Boddington Joseph J.W. McDouall 《Journal of Molecular Structure》1998,434(1-3):239-245
We describe a procedure which may be used to aid selection of the active space in multiconfigurational self-consistent field (MCSCF) calculations for general chemical systems. Starting from a restricted Hartree-Fock calculation, we define a hierarchy of interacting virtual orbitals for every occupied orbital. The most strongly interacting orbitals are then taken to constitute the active space in a configuration interaction (CI) calculation. The natural orbital occupation numbers obtained from the CI calculation are then used to choose the active space to be used in a subsequent MCSCF calculation. We illustrate our method on a number of systems (Li2, B2, C2, carbonyl oxide and the transition state for oxidation of H2S by dioxirane). In all these cases, ‘intuitive’ active spaces are inadequate, as are active spaces derived from the natural orbitals of unrestricted Hartree-Fock calculations. 相似文献
64.
The reducing system NiCl2·2H2O—Li—arenecat (cat is catalyst) was proposed for use to reduce a wide range of organic compounds, including alkenes, alkynes, carbonyl compounds, imines, halogenated derivatives, sulfonates, aromatic compounds, hydrazines, azo and azoxy compounds, N-oxides, and nitrones. The degree of reduction can be controlled for some substrates. Deuterium can be incorporated in the reaction products using nickel chloride deuteriohydrate. Nitrones, N-alkoxyamides, and acyl azides are also reduced with the Li—arenecat system containing no nickel salt. 相似文献
65.
A need for an elaboration of the methods for synthesis and characterization of activated carbons with a requisite porous structure has existed for a long time. One of the methods giving possibility for creating controlled mesopore and micropore structures deals with the steam gasification of various carbon materials. In this work the effects of calcium catalyst on the catalytic steam gasification of active carbons from plum stones and porous polymers are presented. Determination of micropores capacity and specific adsorption in mesopores have been performed by means of the
s
method, but adsorption on the heterogeneous solids was described by the integral equation with various local isotherms. This equation has been solved by the regularization method. Based on this method the changes in structural parameters of active carbons depending on the amount of calcium catalyst were estimated.Nomenclature
d
width of slit-like micropore
-
F(x)
distribution function of the half-width
-
p
vapor pressure of sorbate
-
p/p
N
relative pressure
- PSAC
Plum Stone Active Carbon
-
average pore radius, nm
-
S
1
relative limit of the validity of experimental point on the adsorption isotherm in the computations by means of regularization method
- SAC
Synthetic Active Carbon
-
S
BET
specific surface area calculated by means of BET method, m2/g
-
S
mes
mesopore surface area, m2/g
-
S
mic
micropore surface area, m2/g
-
T
absolute temperature, K
-
V
mes
sorption capacity of mesopores, cm3/g
-
V
mic
sorption capacity of micropores, cm3/g
-
V
p
sorption capacity of pores, cm3/g
- w/w
weight in weight concentration
-
x
half-width of slit-like micropore, nm
-
x
1
maximum of half-width of micropore slit, nm
-
average half-width of slit-like micropore, nm
-
X
min-X
max
integration limits of thex
Greek Letters Greek Letters
variance of average half-width of slit-like micropore, nm2
-
local relative filling of micropores
-
total relative filling of micropores 相似文献
66.
67.
常压气相氧化羰基化合成碳酸二乙酯 总被引:3,自引:0,他引:3
碳酸二乙酯是一种重要的有机化工原料,可广泛用于合成农药如脱叶灵,医药如喹啉酮衍生物,中间体3-氧硫代羧酸酯,还可用于电子管阴极的镀层[1-3]。生产碳酸二乙酯的传统方法为:无水乙醇与光气反应生成氯甲酸乙酯,氯甲酸乙酯继续与乙醇反应生成碳酸二乙酯后经水洗蒸馏制成。使用光气为原料对设备的要求较高。我们在常压下气相羰基化合成碳酸二乙酯[4]:2NO+C2H5OH+0.5O2→2C2H5ONO+H2O(1)CO+2C2H5ONO→(C2H5O)2CO+2NO(2)产生的一氧化氮可与氧气和乙醇进行反应再生为亚硝酸乙酯,符合原子经济反应且几乎不放出对… 相似文献
68.
研究了H4SiW12O40.24H2O(SiW12)在水,乙醇,乙酸,乙酸丁酯中在活性炭上的吸附得出,活性炭微孔结构对SiW12在其表面的吸附起着分子筛作用,水溶剂化的SiW12分子可顺利进行活性1.7nm左右的微孔,而其它溶剂化的SiW12分子,则需较大的孔径,提出了SiW12在活性炭表面吸附的微孔中孔扩散模型。 相似文献
69.
Stephen P. Walch 《中国化学会会志》1995,42(2):221-231
Computed potential energy surfaces are often required for computation of such observables as rate constants as a function of temperature, product branching ratios, and other detailed properties. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method with the Dunning correlation consistent basis sets to obtain accurate energetics, gives useful results for a number of chemically important systems. Applications to complex reactions leading to NOx and soot formation in hydrocarbon combustion are discussed. 相似文献
70.
The diffusion length of charge carriers in the active layer of a perovskite solar cell (PSC) of the structure Glass/PEDOT: PSS/CH3NH3PbI3/PC60BM/Al is modelled. It is found that the diffusion length depends on the position x in the active layer measured from the PEDOT: PSS interface, Urbach energy and temperature. By varying the voltage in the range from zero to , it is shown that the dependence of diffusion length on the position x in the active layer reduces at higher voltage. The combined influence of applied voltage and temperature on the diffusion length of charge carriers is investigated and it is found that in the low voltage range the diffusion length is temperature independent, but it becomes significantly temperature dependent at higher voltages. Also, it is found that the diffusion length decreases as the applied voltage increases and this reduction becomes much more significant at higher voltage and temperatures. The combined influence of applied voltage and Urbach energy on diffusion length of charge carriers reveals that the diffusion length decreases when both the applied voltage and Urbach energy increase. However, the reduction in the diffusion length due to the increase in Urbach energy becomes less significant at higher voltage. 相似文献