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71.
Aza-Michael addition of 4-aryl-1H-1,2,3-triazoles to 2-cycloalken-1-ones has been studied in the presence of DABCO as organic base. The reactions were carried out in acetonitrile at room temperature to provide 2,4-disubstituted 2H-1,2,3-triazoles as major adducts and 1,4-disubstituted 1H-1,2,3-triazoles as minor adducts. Though the reaction times are longer (4–8 days), the two regioisomers were separated by using column chromatography and the adducts were obtained in very good to excellent combined chemical yields. The electron-rich and electron-poor substituents on aryl moiety of 4-aryl-triazoles could tolerate the reaction conditions to afford the title adducts. 相似文献
72.
Obaid-Ur-Rahman Abid Muhammad Nawaz Nasim Hasan Rama Peter Langer 《Tetrahedron letters》2010,51(4):657-7025
The [4+2] cycloaddition of 1-ethoxy-2-chloro-1,3-bis(trimethylsilyloxy)-1,3-diene with dimethyl acetylenedicarboxylate (DMAD) afforded dimethyl 4-chloro-3,5-dihydroxyphthalate. Site-selective Suzuki-Miyaura reactions of its bis(triflate) provide a convenient approach to 3,5-diaryl-4-chlorophthalates containing two different aryl groups. 相似文献
73.
Fusion toxins are an emerging class of targeted therapeutics for the treatment of cancer. Diphtheria toxin-stem cell factor
(DT-SCF) is one such novel fusion toxin designed to target malignancies expressing c-kit. Since, c-kit overexpression has
been reported on many types of cancers, it appeared to be a reasonably good molecule to target. In the present study, we report
construction, expression, purification, and characterization of DT-SCF. DT-SCF gene coding for 1–387 amino acids of diphtheria
toxin, His-Ala linker, 2–141 amino acids of SCF was cloned into expression vector with C terminal His tag. The induced DT-SCF
protein was exclusively expressed in insoluble fraction. Purification of DT-SCF was achieved by inclusion body isolation and
metal affinity chromatography under denaturing and reducing conditions. Purified DT-SCF was renatured partially on-column
by gradually reducing denaturant concentration followed by complete refolding through rapid dilution technique. Cell viability
assay provided the evidence that DT-SCF is a potent cytotoxic agent selective to cells expressing c-kit. The novelty of this
study lies in employing SCF as a ligand in construction of fusion toxin to target wide range of malignancies expressing c-kit.
Efficacy of DT-SCF fusion toxin was demonstrated over a range of malignancies such as chronic myeloid leukemia (K562), acute
lymphoblastic leukemia (MOLT4), pancreatic carcinoma (PANC-1), and cervical carcinoma (HeLa 229). This is the first study
reporting specificity and efficacy of DT-SCF against tumor cells expressing c-kit. There was significant correlation (P = 0.007) between c-kit expression on cells and their sensitivity to DT-SCF fusion toxin. 相似文献
74.
Jin Young Park Hong Chae Jung G. Seeta Rama Raju Byung Kee Moon Jung Hyun Jeong Jung Hwan Kim 《Solid State Sciences》2010,12(5):719-724
A series of Eu3+ ions co-doped (Gd0.9Y0.1)3Al5O12:Bi3+, Tb3+ (GYAG) phosphors have been synthesized by means of solvothermal reaction method. The XRD pattern of GYAG phosphor sintered at 1500 °C confirms their garnet phase. The luminescence properties of these phosphors have been explored by analyzing their excitation and emission spectra along with their decay curves. The excitation spectra of the GYAG:Bi3+, Tb3+, Eu3+ phosphors consists of broad bands in the shorter wavelength region due to 4f8 → 4f75d1 transition of Tb3+ ions overlapped with 6s2 → 6s16p1 (1S0 → 3P1) transition of Bi3+ ions and the charge transfer band of Eu3+–O2?. The present phosphors exhibit green and red colors due to 5D4 → 7F5 transition of Tb3+ ions and 5D0 → 7F1 transition of Eu3+ ions, respectively. The emission was shifted from green to red color by co-doping with Eu3+ ions, which indicate that the energy transfer probability from Tb3+ to Eu3+ ions are dependent strongly on the concentration of Eu3+ ions. 相似文献
75.
T. Raghavendra RaoCh. Rama Krishna U.S. Udayachandran ThampyCh. Venkata Reddy Y.P. ReddyP. Sambasiva Rao R.V.S.S.N. Ravikumar 《Physica B: Condensed Matter》2011,406(11):2132-2137
The effect of Li2O content in vanadyl doped 20ZnO+xLi2O+(30−x)Na2O+50B2O3 (5≤x≥25) glasses has been studied with respect to their physical and structural properties. The absence of sharp peaks in XRD spectra of these glass samples confirms the amorphous nature. The physical parameters like density, refractive index, ionic concentration and electronic polarizability vary non-linearly with x mol% depending on the diffusivities of alkali ions. EPR and optical absorption spectra reveal that the resonance signals are characteristics of VO2+ ions in tetragonally compressed octahedral site. Spin-Hamiltonian, crystal field, tetragonal field and bonding parameters are found to be in good agreement with the other reported glass systems. The tetragonal distortion (g⊥-g∥) and Dt reveals that their values vary non-linearly with Li2O content and reaches a minimum at x=10 mol%. An anomaly of character has been observed in all the properties of vanadyl doped glass systems, which gives a clear indication of mixed alkali effect. 相似文献
76.
D. Madhavi LathaV.G.K.M. Pisipati C. Rama Chandra PrabhuP.V. Datta Prasad 《Journal of Molecular Liquids》2011,164(3):187-190
The thermodynamic parameters like Moelwyn-Hughes parameter (C1), reduced molar volume (V~), isochoric temperature coefficient of internal pressure (X), Huggin's parameter (F), Gruneisen parameter (Γp), isothermal microscopic Gruneisen parameter, Sharma parameter (So), fraction free volume (f) and (A?) a dimensionless thermal parameter, etc and the Beyer's nonlinearity parameter (B/A) were deduced employing the thermal expansion coefficient derived from density data for the homologues series of compounds terephthalyidene-bis-p-n-alkyl anilines, TBnA with n = 5 to 10,12,14,16 and 18. Further, it is found that the variation of molecular radius, Mr increases with the increase of alkyl chain number, with a core radius of 4.78 Å and the increment for methylene unit is 0.086 Å . The results were discussed with the body of the data available. 相似文献
77.
78.
Chintakunta RameshB. Rama Raju Veerababurao KavalaChun-Wei Kuo Ching-Fa Yao 《Tetrahedron》2011,67(6):1187-1192
A simple route for the synthesis of 1,4-benzoxazin-3-(4H)-ones is described herein. This method involves the reductive cyclization of 2-(2-nitrophenoxy)acetonitrile adducts in the presence of Fe/acetic acid in good to excellent yields. This system was compatible with various other functional groups. 相似文献
79.
K Rama Mohana Rao 《Pramana》1990,35(2):141-149
A flow chart (inverted ‘tree’) for generating and identifying the 58 magnetic and 18 polychromatic point groups using a classification
for the 32 generating crystallographic point groups is suggested. The idea of colour generator is explored for generating
the colour symmetry point groups. The advantages in presenting the identification of colour groups through a tree are discussed. 相似文献
80.
M. V. Rama Krishna 《Journal of computational chemistry》1990,11(5):629-635
An analytical procedure is presented for the determination of the proper dissociation configurations of a molecule. We illustrate this procedure by determining the proper dissociation configurations of many electronic states of the first-row diatomic molecules and ozone. Finally, a few simple guidelines are provided to help in the identification of the important configurations needed for proper dissociation of a molecule. 相似文献