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991.
The bifunctional metalloligand bis(carboxyethylgermanium)sesquioxide, (HOOCCH2CH2Ge)2O3, was employed in the systematic high‐throughput (HT) investigation of the system Zn2+/(HOOCCH2CH2Ge)2O3/H2O/C4H9OH. Two new metal‐organogermanates Zn[(OOCCH2CH2Ge)2O3] ( 1 ) and Zn2(O3GeCH2CH2COO) ( 2 ) were discovered that show two new structural motifs for this class of compounds. Whereas in compound 1 a formal intercalation in the structure of (HOOCCH2CH2Ge)2O3 is observed, 2 exhibits a new layered structure composed of CGeO3 and ZnO4 unit linked by μ3‐oxygen atoms. Both connectivity modes lead to dense three‐dimensional framework structures. 相似文献
992.
Dr. Wei Su Dr. Peiyuan Li Libei Yao Fang Yang Prof. Lifang Liang Juan Chen 《Chemphyschem》2011,12(6):1143-1147
We demonstrate a simple route to fabricating copper circuit patterns on the surface of polyimide film. The copper pattern can be obtained in three steps: 1) Formation of partially potassium hydroxide modified pattern via a screen‐printing process, 2) formation of macromolecular metal complex with copper, and 3) copper metallization by DMAB reduction. The morphologies of these copper patterns are determined by cross‐sectional transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), and atomic force microscopy (AFM). Furthermore, the growing process of the metallic copper film is investigated. The direct patterning of copper patterns onto polyimide substrates is promising for use in electronics industry as a large‐area and low‐cost processing technique. 相似文献
993.
Mechanistic Insights into the Ni‐Catalyzed Reductive Carboxylation of C−O Bonds in Aromatic Esters with CO2: Understanding Remarkable Ligand and Traceless‐Directing‐Group Effects 下载免费PDF全文
Yan‐Li Han Bing‐Yuan Zhao Kun‐Yao Jiang Hui‐Min Yan Dr. Zhu‐Xia Zhang Dr. Wen‐Jing Yang Prof. Dr. Zhen Guo Prof. Dr. Yan‐Rong Li 《化学:亚洲杂志》2018,13(12):1570-1581
The mechanism of the Ni0‐catalyzed reductive carboxylation reaction of C(sp2)?O and C(sp3)?O bonds in aromatic esters with CO2 to access valuable carboxylic acids was comprehensively studied by using DFT calculations. Computational results revealed that this transformation was composed of several key steps: C?O bond cleavage, reductive elimination, and/or CO2 insertion. Of these steps, C?O bond cleavage was found to be rate‐determining, and it occurred through either oxidative addition to form a NiII intermediate, or a radical pathway that involved a bimetallic species to generate two NiI species through homolytic dissociation of the C?O bond. DFT calculations revealed that the oxidative addition step was preferred in the reductive carboxylation reactions of C(sp2)?O and C(sp3)?O bonds in substrates with extended π systems. In contrast, oxidative addition was highly disfavored when traceless directing groups were involved in the reductive coupling of substrates without extended π systems. In such cases, the presence of traceless directing groups allowed for docking of a second Ni0 catalyst, and the reactions proceed through a bimetallic radical pathway, rather than through concerted oxidative addition, to afford two NiI species both kinetically and thermodynamically. These theoretical mechanistic insights into the reductive carboxylation reactions of C?O bonds were also employed to investigate several experimentally observed phenomena, including ligand‐dependent reactivity and site‐selectivity. 相似文献
994.
Visible‐Light‐Driven Chemoselective Hydrogenation of Nitroarenes to Anilines in Water through Graphitic Carbon Nitride Metal‐Free Photocatalysis 下载免费PDF全文
Green and efficient procedures are essential for the chemoselective hydrogenation of functionalized nitroarenes to form industrially important anilines. Herein, it is shown that visible‐light‐driven, chemoselective hydrogenation of functionalized nitroarenes with groups sensitive to forming anilines can be achieved in good to excellent yields (82–100 %) in water under relatively mild conditions and catalyzed by low‐cost and recyclable graphitic carbon nitride. The process is also applicable to gram‐scale reaction, with a yield of aniline of 86 %. A study of the mechanism reveals that visible‐light‐induced electrons are responsible for the hydrogenation reactions, and thermal energy can also promote the photocatalytic activity. A study of the kinetics shows that this reaction possibly occurs through one‐step hydrogenation or stepwise condensation routes. A wide range of applications can be expected for this green, efficient, and highly selective photocatalysis system in reduction reactions for the synthesis of fine chemicals. 相似文献
995.
Dr. Rud Wegscheider 《Monatshefte für Chemie / Chemical Monthly》1895,16(1):153-158
Ohne Zusammenfassung 相似文献
996.
Dr. August Chwala 《Colloid and polymer science》1931,56(1):117-122
Ohne Zusammenfassung 相似文献
997.
998.
J. G. C. M. van Duijneveldt-van de Rijdt Dr. F. B. van Duijneveldt 《Theoretical chemistry accounts》1970,19(1):83-91
Using perturbation theory of intermolecular forces (including exchange effects) hydrogen-bond energies are calculated for a simple model representing the water dimer. Several orientations of the proton acceptor with respect to the O...O axis are considered and it is found that the optimum orientation depends sensitively on the oxygen lone-pair hybridization assumed. The main orientation-dependent energy term is found to be the classical electrostatic energy between the unperturbed molecules. The relation of the present results to the structures of the ices I and Ic, and to the results of recent SCF studies are discussed briefly.
For some recent CNDO/2 calculations on (H2O)2 which concentrate mainly on rotations of the donor see Ref. [5]. 相似文献
Zusammenfassung Die Energien von Wasserstoffbindungen werden für ein einfaches Modell des dimeren Wassers mit Hilfe der Störungstheorie für intermolekulare Kräfte (mit Austauscheffekten) berechnet. Verschiedene Orientierungen des Protonen-Akzeptors bezüglich der O ... O-Achse werden untersucht; man findet, daß die optimale Orientierung empfindlich von der angenommen Hybridisierung des einsamen Elektronenpaars des Sauerstoffs abhängt. Der hauptsächliche, von der Orientierung abhängige Energieterm ist die klassische elektrostatische Energie zwischen den beiden ungestörten Molekülen. Die Beziehung der vorliegenden Ergebnisse zu den Strukturen von Eis I und Ic sowie zu den Ergebnissen kürzlicher SCF-Rechnungen wird kurz diskutiert.
For some recent CNDO/2 calculations on (H2O)2 which concentrate mainly on rotations of the donor see Ref. [5]. 相似文献
999.
Summary Previous studies have indicated that non-ionic surface active agents, such as n-dodecylhexaoxyethylene glycol monoether, confer considerable protection on silver iodide sols to flocculation by inorganic cations. In the present study the effects of hydrolysis of the flocculating cations, lanthanum, aluminium and thorium have been examined. It was found that with the hydrolysed cations the protective action of the non-ionic surface active agent was considerably diminished. It was deduced that the hydrolysed species are more strongly adsorbed than the nonionic surface active agent and either displace the latter from the surface or form species which are large enough to cause flocculation by interparticle bridging.
With 6 figures and 1 table 相似文献
Zusammenfassung Vorausgehende Untersuchungen haben gezeigt, daß nichtionische oberflächenaktive Substanzen wie n-Dodecylhexaoxyäthylen-glykol-monoäther beträchtliche Schutzwirkung Silberjodidsolen gegenüber Flokkung durch anorganische Kationen verleihen. In der vorliegenden Untersuchung wird die Wirkung der Hydrolyse flockender Kationen, Lanthan, Aluminium und Thorium, geprüft. Es wurde gefunden, daß durch die hydrolisierten Kationen die Schutzwirkung der nichtionischen oberflächenaktiven Substanz beträchtlich vermindert wird. Daraus ist zu schließen, daß die hydrolisierte Ionenart stärker als das nichtoberflächenaktive Agens adsorbiert wird und deshalb das letztere von der Oberfläche entfernt wird oder genügend große interpartikuläre Brücken, bildet, um Flockung zu verursachen.
With 6 figures and 1 table 相似文献
1000.
Dr. Theodor N. Kleinert Dr. Roderick E. Townshend 《Monatshefte für Chemie / Chemical Monthly》1970,101(2):375-379
Zusammenfassung Die beim Verstrecken sowie Mahlen von künstlichen organischen Fasermaterialien (Polyester-, Polyamid- und Viskosefasern) als Folge homolytischer Kettenspaltungen auftretende Freiradikalbildung wurde untersucht.
Mit 3 Abbildungen
Die Elektronspinresonanz-Messungen wurden im Chemischen Institut der Sir George Williams University, Montreal, Canada, durchgeführt. 相似文献
Mechanochemical reactions in synthetic organic fibres
The formation of free radicals due to homolytic chain fission occurring in the course of stretching and grinding of synthetic organic fibres (polyester, polyamide, and viscose fibres) has been investigated by means of ESR spectroscopy.
Mit 3 Abbildungen
Die Elektronspinresonanz-Messungen wurden im Chemischen Institut der Sir George Williams University, Montreal, Canada, durchgeführt. 相似文献