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961.
Polyamide I1 (PAll) and its nanocomposites with different organoclay loadings were prepared by melt-compounding and subsequent pelletizing. The crystal phase transitions of PAl 1 and its clay nanocomposites were investigated by variable-temperature X-ray diffraction. It was found that the Brill transition of the nanocomposite was 20 K higher than that of the neat PAl 1 for both heating and cooling processes. The PAl 1 d-spacings of the nanocomposites were observed to be smaller than those of the neat PAl 1 for melt crystallization. The constraints imposed by the addition of layered clay, restricting the thermal expansion of the polymer chains, are probably responsible for such a reduction of the d-spacing. 相似文献
962.
对紫外荧光硫分析仪用石英燃烧管进行了结构改进,在原结构设计的基础上,增加了裂解氧预热管、挡板和氧气反吹口等。实验表明,相比于原结构设计的石英燃烧管进样量20μL和检出限0.2 mg/L,改进后的燃烧管进样量提高到了100μL,检出限达0.05 mg/L,线性范围为0.1~600 mg/L,相关系数大于0.999。采用改进后的燃烧管测定10.0 mg/L硫含量标准物质,其相对偏差为–1.5%~3.1%,测定结果的相对标准偏差为1.77%(n=10),两者均符合油品硫含量检测要求。改进后的燃烧管可替代市场上的其它国产石英燃烧管,进行油品中硫含量的测定。 相似文献
963.
Qunfeng Fu Dr. Hongyu Li Dongban Duan Changlun Wang Siyong Shen Prof. Dr. Huimin Ma Prof. Dr. Zhibo Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(48):21730-21736
Radiation-induced cleavage for controlled release in vivo is yet to be established. We demonstrate the use of 3,5-dihydroxybenzyl carbamate (DHBC) as a masking group that is selectively and efficiently removed by external radiation in vitro and in vivo. DHBC reacts mainly with hydroxyl radicals produced by radiation to afford hydroxylation at para/ortho positions, followed by 1,4- or 1,6-elimination to rescue the functionality of the client molecule. The reaction is rapid and can liberate functional molecules under physiological conditions. This controlled-release platform is compatible with living systems, as demonstrated by the release of a rhodol fluorophore derivative in cells and tumor xenografts. The combined benefits of the robust caging group, the good release yield, and the independence of penetration depth make DHBC derivatives attractive chemical caging moieties for use in chemical biology and prodrug activation. 相似文献
964.
Fumaric acid was reacted with the binary superacidic systems HF/SbF5 and HF/AsF5. The O,O'-diprotonated [C4H6O4]2+([MF6]–)2 (M = As, Sb) and the O-monoprotonated [C4H5O4]+[MF6]– (M = As, Sb) species are formed depending on the stoichiometric ratio of the Lewis acid to fumaric acid. The colorless salts were characterized by low-temperature vibrational spectroscopy. In case of the hexafluoridoantimonates single-crystal X-ray structure analyses were carried out. The [C4H6O4]2+([SbF6]–)2 crystallizes in the monoclinic space group C2/c with four formula units per unit cell and [C4H5O4]+[SbF6]– crystallizes in the triclinic space group P1 with one formula unit per unit cell. The protonation of fumaric acid does not cause a notable change of the C=C bond length. The experimental data are discussed together with quantum chemical calculations of the cations [C4H6O4 · 4 HF]2+ and [C4H6O4 · 2 H2CO · 2 HF]2+. 相似文献
965.
Mohd Muddassir Abdullah Alarifi Mohd Afzal Ahmad Alowais Naaser A. Y. Abduh 《无机化学与普通化学杂志》2020,646(14):1205-1211
This article outlines the magnetic features of a new six–coordinate high-spin cobalt(II) complex cis-[CoII(tmphen)2(NCS)2] ( 1 ) achieved via the reactions of cobalt(II) thiocyanate with 3,4,7,8-tetramethyl-1,10-phenanthroline. The complex 1 was thoroughly characterized by different analytical and spectroscopic techniques and further confirmed by single X-ray crystal diffraction pattern. Complex 1 is a neutral molecule and adopt highly distorted six-coordinate CoN6 octahedral coordination sphere surrounded by two thiocyanate N atoms in cis locations and the equatorial plane is occupied by two imine N atoms from the two tmphen ligand while the remaining two imine N atoms reside in the axial positions. Magnetic susceptibility data of complex 1 revealed that the χΜT values decrease significantly to a value of 1.49 cm3 · K · mol–1 at 2.0 K on decreasing temperatures below 100 K, mainly ascribed to the significant spin–orbit coupling (SOC) of six-coordinate CoII ions. Furthermore, a field-dependence measurement was performed at 2 K, which shows a positive curvature up to 27 kOe, while it becomes linear up to 2.01 NμB, which authenticated the fact that only the lowest Kramers doublet of ground state is appreciably populated. 相似文献
966.
Chun-Yaung Lu Tsung-Yen Lee Chia-Chun Chou 《International journal of quantum chemistry》2020,120(1):e26055
The moving boundary truncated grid (TG) method is used to study wave packet dynamics of multidimensional quantum systems. As time evolves, appropriate Eulerian grid points required for propagating a wave packet are activated and deactivated with no advance information about the dynamics. This method is applied to the Henon-Heiles potential and wave packet barrier scattering in two, three, and four dimensions. Computational results demonstrate that the TG method not only leads to a great reduction in the number of grid points needed to perform accurate calculations but also is computationally more efficient than the full grid calculations. 相似文献
967.
Attempts to synthesize complexes of group 6 carbonyl compounds [M(CO)6] (M = Cr, Mo, W) with the carbone C(PPh3)2 ( 1 ) via the photo chemically created adducts [(CO)5M(THF)] lead to quantitative formation of the salts [HC(PPh3)2]2[M2(CO)10] ( 2 , Cr; 3 , Mo; 4 , W). Alternatively, a long-time thermal reaction of [Mo(CO)6] performed with 1 in THF generates a series of products initiated by a Wittig-type reaction. In addition to 3 , minor amounts of [(CO)5MoCCPPh3] ( 8 ), [(CO)5MoO2CC{PPh3}2] ( 5 ), and the carbonate complexes [HC(PPh3)2]2[(CO)5Mo(CO3)Mo(CO)4] ( 6 ) and [HC(PPh3)2]2[(CO)4Mo(CO3)Mo(CO)4] ( 7 ) were found. Compounds 2 , 3 , 5 , 6 , and 7 were characterized by X-ray analyses, 31P NMR, and IR spectroscopy. The water, necessary for the formation of the carbonate, stems from decomposition of THF. 相似文献
968.
Shiwani Berry Shamsher S. Bari Pooja Yadav Ankita Garg Sadhika Khullar Sanjay K. Mandal 《合成通讯》2020,50(19):2969-2980
Abstract An efficient protocol for the stereoselective synthesis of pyrazolo[5,1-b]thiazole-3-carboxylate tethered β-lactam conjugates 8a–j from novel pyrazolo [5,1-b]thiazole-3-carboxylate substituted Schiff’s bases 6a–f is reported here. The reaction between various ketene precursors and novel Schiff’s bases 6a–f afforded exclusive formation of trans-β-lactams 8a–j. The substrate scope of this approach was investigated extensively by varying different groups (R, Z). All the novel compounds were characterized using various spectroscopic techniques, such as FT-IR, 1H NMR, 13C NMR, elemental analysis, 13C NMR (DEPT-135), and mass spectrometry in representative cases. Single crystal X-ray crystallographic study of trans-ethyl 7-(1-(4-methoxyphenyl)-4-oxo-3-phenoxyazetidin-2-yl)-6-methyl-2-(methylthio)pyrazolo[5,1-b]thiazole-3-carboxylate 8a has confirmed the molecular structure and the stereochemical outcome. To the best of our knowledge, the synthesis of such types of Schiff’s bases and β-lactam conjugates has not been reported so far. 相似文献
969.
Pariya Bazyari Masoumeh Tabatabaee Navid Nasirizadeh Michal Dušek Václav Eigner 《无机化学与普通化学杂志》2020,646(17):1444-1448
Reaction of 4-amino-5-methyl-1,2,4-triazol-3(2H)-thione (AMTT) and 4-amino-6-methyl-3-thio-3,4-dihydro-1,2,4-triazin-5(2H)-one (AMTTO) with 2-hydroxybenzaldehyde led to the synthesis of corresponding Schiff base ligands [(Z)-4-((2-hydroxybenzylidene)amino)-3-methyl-1H-1,2,4-triazole-5(4H)-thione ( L1 ) and (Z)-4-((2-hydroxybenzylidene)amino)-6-methyl-3-thioxo-3,4-dihydro-1,2,4-triazin-5(2H)-one ( L2 )]. Treatment of synthesized Schiff base ligands with CuCl provided the complexes [Cu(L1)3Cl] ( 1 ) and [Cu(L2)2Cl] ( 2 ). Synthesized complexes were characterized by elemental analyses, IR spectroscopy and X-ray diffraction studies. Complex 1 consists of a metal ion coordinated with one chloride ion and three Schiff base ligands via sulfur atoms in a distorted tetrahedral environment, whereas 2 consists of a metal ion coordinated with one chloride ion and two sulfur atoms from two different Schiff base ligands in a trigonal planar arrangement. Crystal data for 1 at –153 °C revealed an orthorhombic space group Fdd2, a = 34.8088(7), b = 33.8156(8), c = 11.6142(2) Å, Z = 16, R1 = 0.0357; for 2 at –178 °C the symmetry was triclinic, space group P1 , a = 7.27520(10), b = 15.4620(2), c = 23.7985(4) Å, α = 72.1964(13), β = 86.5208(12), γ = 89.8597(11)°, Z = 4, R1 = 0.0359. 相似文献
970.
Abeer F. Shunnar Dr. Bhausaheb Dhokale Dr. Durga Prasad Karothu David H. Bowskill Dr. Isaac J. Sugden Dr. Hector H. Hernandez Prof. Panče Naumov Dr. Sharmarke Mohamed 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(21):4752-4765
The discovery of molecular ionic cocrystals (ICCs) of active pharmaceutical ingredients (APIs) widens the opportunities for optimizing the physicochemical properties of APIs whilst facilitating the delivery of multiple therapeutic agents. However, ICCs are often observed serendipitously in crystallization screens and the factors dictating their crystallization are poorly understood. We demonstrate here that mechanochemical ball milling is a versatile technique for the reproducible synthesis of ternary molecular ICCs in less than 30 min of grinding with or without solvent. Computational crystal structure prediction (CSP) calculations have been performed on ternary molecular ICCs for the first time and the observed crystal structures of all the ICCs were correctly predicted. Periodic dispersion-corrected DFT calculations revealed that all the ICCs are thermodynamically stable (mean stabilization energy=−2 kJ mol−1) relative to the crystallization of a physical mixture of the binary salt and acid. The results suggest that a combined mechanosynthesis and CSP approach could be used to target the synthesis of higher-order molecular ICCs with functional properties. 相似文献