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251.
Zusammenfassung Um der oft gehörten Meinung entgegenzutreten, die energetischen Wirkungsgrade lebender Organismen seien wesentlich höher als die technischer Verfahren, werden entsprechende Werte miteinander verglichen. Der sehr niedrige Wirkungsgrad der Photosynthese zusammen mit der kleinen Energiedichte der Sonnenstrahlung erzwang ab einer kritischen Größe die Aufspaltung in Energiesammler, die Pflanzen, und Verbraucher chemischer Energie, den Tieren. Dank den 10 mal höheren Wirkungsgraden in der Technik, lassen sich Solarmobile bauen, die von der auf sie fallenden Sonnenstrahlung angetrieben werden. Wegen des Multiplikationsgesetzes der Teilwirkungsgrade ergeben sich sowohl für die Speicherung der Sonnenenergie in den fossilen Brennstoffen wie in der Nahrungskette extrem niedrige Wirkungsgrade.
Herrn Prof. Dr.-Ing. U. Grigull zum 75. Geburtstag gewidmet 相似文献
Efficiencies in the world of life and in engineering
One often hears the opinion, that the efficiencies in the world of life are higher than in engineering. To disprove this, many values of efficiency of corresponding processes are compared. The very low efficiency of photosynthesis in living plants together with the low density of solar radiation has led the world of life to split into collectors of energy, the plants, and consumers of chemical energy, the animals. Thanks to the ten times higher efficiencies of solar cells, it is possible, to produce solar mobiles, vehicles that move driven by solar radiation.
Herrn Prof. Dr.-Ing. U. Grigull zum 75. Geburtstag gewidmet 相似文献
252.
253.
Dr. F. C. Goodrich 《Colloid and polymer science》1967,219(2):156-159
Summary Under steady state conditions the reduction in the diffusive flux into a sphere due the presence of a neighboring, identical sphere is calculated. Taking the flux into a sphere as 1 when the particles are at infinite separation, the flux decreases to a minimum value of 0.693 when the spheres are touching.
With 2 figures 相似文献
Zusammenfassung Unter stationären Bedingungen wird die Abnahme des Diffusionsflusses in eine Kugel, bedingt durch eine benachbarte identische Kugel, berechnet.Wird der Diffusionsfluß in eine Kugel gleich 1 gesetzt, wenn die Partikel unendlich weit voneinander entfernt sind, so nimmt der Diffusionsfluß auf einen Minimalwert von 0,693 ab, wenn sich die Kugeln berühren.
With 2 figures 相似文献
254.
Dr. H. Demel Dipl.-Ing H. J. Grießer Prof. Dr. K. Hummel 《Colloid and polymer science》1977,255(11):1131-1132
Ohne ZusammenfassungMit 1 Abbildung und 1 Tabelle 相似文献
255.
Dr. Ulrich Mayer 《Monatshefte für Chemie / Chemical Monthly》1978,109(2):421-433
A model has been developed for calculating the enthalpy, entropy and free energy change associated with the creation of cavities in a liquid the size of which corresponds to the volume occupied by a solvent molecule. The molar enthalpy change H
cav equals the molar enthalpy of vaporization of the liquid, the free energy change G
cav is given by G
cav=–RT ln (V
m
·p
eq
/RT) (V
m
=molar volume,p
eq
=equilibrium vapor pressure) and is related to the standard free energy of vaporization. This relationship provides an estimate of the free energy of cavity formation required to accomodate a substrate in the liquid. It has been shown, that the free energy of solvation of a substrate can be dissected into different contributions accounting for (1) the concentration dependence of partial molar free energy quantities, (2) the formation of holes in the solvent, (3) the existence of specific, short range solute-solvent interactions and (4) the dielectric polarization of the medium. Application of this concept leads to an equation of the general form G
S
–G
R
=a(DN
S
–DN
R
)+b(AN
S
–AN
R
)+c(G
vp
oS
–G
vp
oR
), where G represents the free energy of reaction or activation,DN the donor number,AN the acceptor number and G
vp
o
the standard free energy of vaporization of a solventS and a reference solventR, resp.
Mit 3 Abbildungen 相似文献
Mit 3 Abbildungen 相似文献
256.
Yellowish crystals of K2[(UO2)As2O7] ( 1 ) have been synthesized by solid‐state reactions method. The structure of 1 [orthorhombic, Pmmn, a = 12.601(2), b = 13.242(2), c = 5.621(1) Å, V = 937.9(3) Å3, Z = 4] has been solved by direct methods and refined to R1 = 0.049, wR2 = 0.1060 for 1059 observed reflections. The structure of 1 is based upon [(UO2)As2O7]2? sheets formed by corner sharing between [UO6]6? distorted octahedra and [As2O7]4? polyarsenate groups. The K+ cations are either in eightfold or tenfold coordination and are located between the sheets. The topology of the uranyl arsenate sheet is related to silicate minerals of the melilite group and related synthetic silicate, aluminate and germanate compounds. 相似文献
257.
Résumé La méthyl-9-trihydroxy-2,3,7-fluorone-6 permet de déceler les ions de l'antimoine, en présence de tous autres cations et anions. Les conditions deph (ph = 4) sont à observer rigoureusement.Ce nouveau réactif est avantageusement utilisé dans la méthode d'analyse à la touche ou par empreinte.Les limites de sensibilité sont: en godet 0,2; sur papier gélatine 0,5; sur papier filtre 0,8.
Summary Methyl-9-trihydroxy-2,3,7-fluorone-6 is a reagent which allows to detect antimony ion in the presence of all the other cations and anions. Aph value of 4 must be strictly maintained.This new reagent can be advantageously applied for spot test and offprint analysis.Limits of identification: On the spot test plate 0,2; On gelatine paper 0,5; On filter paper 0,8.
Zusammenfassung Das Methyl-9-trioxy-2,3,7-fluoron-6 gestattet den Nachweis des Antimonions in Gegenwart aller anderen Kationen und Anionen. Dieph-Bedingungen (ph = 4) sind streng einzuhalten.Dieses neue Reagens läßt sich mit Vorteil zur Tüpfel- oder Abdruckanalyse verwenden.Erfassungsgrenzen: auf der Tüpfelplatte 0,2; auf Gelatinepapier 0,5; auf Filtrierpapier 0,8.相似文献
258.
Chihiro Kachi‐Terajima Dr. Takamasa Akatsuka Masa‐aki Kohbara Satoshi Takamizawa Dr. 《化学:亚洲杂志》2007,2(1):40-50
The crystalline one‐dimensional compound, [RhII2(bza)4(pyz)]n ( 1 ) (bza=benzoate, pyz=pyrazine) demonstrates gas adsorbency for N2, NO, NO2, and SO2. These gas‐inclusion crystal structures were characterized by single‐crystal X‐ray crystallography as 1 ?1.5 N2 (298 K), 1 ?2.5 N2 (90 K), and 1 ?1.95 NO (90 K) under forcible adsorption conditions and 1 ?2 NO2 (90 K) and 1 ?3 SO2 (90 K) under ambient pressure. Crystal‐phase transition to the P space group that correlates with gas adsorption was observed under N2, NO, and SO2 conditions. The C2/c space group was observed under NO2 conditions without phase transition. All adsorbed gases were stabilized by the host lattice. In the N2, NO, and SO2 inclusion crystals at 90 K, short interatomic distances within van der Waals contacts were found among the neighboring guest molecules along the channel. The adsorbed NO molecules generated the trans‐NO???NO associated dimer with short intermolecular contacts but without the conventional chemical bond. The magnetic susceptibility of the NO inclusion crystal indicated antiferromagnetic interaction between the NO molecules and paramagnetism arising from the NO monomer. The NO2 inclusion crystal structure revealed that the gas molecules were adsorbed in the crystal in dimeric form, N2O4. 相似文献
259.
Yuko Ouchi Yasuhiro Morisaki Dr. Tomoki Ogoshi Dr. Yoshiki Chujo Prof. Dr. 《化学:亚洲杂志》2007,2(3):397-402
A reaction of the P‐chiral compound (S,S)‐1,2‐bis(boranato(tert‐butyl)methylphosphino)ethane with an azobenzene derivative gave stimuli‐responsive polymers with P‐chiral phosphines in the main chain. This is the first example of a stimuli‐responsive P‐chiral polymer. The polymer isomerized from the trans to the cis form upon UV irradiation and reverted to the trans form reversibly. The polymer was able to coordinate to platinum, and the resulting polymer complex exhibited the Cotton effect owing to the chirality of the phosphorus atoms. The structure of the P‐chiral polymer obtained could be changed reversibly by light and thermal stimuli, and the polymer chain was induced to rotate helically when complexed with transition metals through the chiral phosphorus atoms. 相似文献
260.
Moraes ML Bonardi C Mendonça CR Campana PT Lottersberger J Tonarelli G Oliveira ON Beltramini LM 《Colloids and surfaces. B, Biointerfaces》2005,41(1):15-20
The study of interactions between biological molecules and model membranes is essential for the understanding of a number of physiological mechanisms involved in viral infections and dissemination. In this paper, the analysis of the interaction between a peptide from the p24 protein of Human Immunodeficiency Virus type 1 (HIV-1) and a phospholipid monolayer has pointed to a cooperative response in which very small amounts of peptide p24-1 (e.g. 0.05 mol%) can lead to measurable effects. Monolayer surface pressure and surface potential isotherms were affected for peptide concentrations as low as 0.05 mol%, with saturation at 0.5 mol%. The expansion effect from p24-1 is confirmed by changes in morphology of the monolayers using Brewster angle microscopy. Even though p24-1 is disordered in aqueous solutions, the interaction with dipalmitoyl phosphatidylcholine (DPPC) causes it to adopt an alpha-helix structure, as shown by circular dichroism (CD) data for multilamellar vesicles (MLV). The expansion of the phospholipid monolayer in a cooperative way may imply that p24-1 has potential antiviral activity, by participating in the cell rupture, with no need of specific receptors in the membrane. 相似文献