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951.
The palladium-catalyzed semi-hydrogenation of alkynes to trans- or cis-alkenes employing HSiEt3 as the reductant is developed. The CuSO4 played a significant role for the trans/cis stereoselectivity. The labeling study revealed that the two olefinic hydrogen atoms came from HSiEt3 and H2O, respectively. 相似文献
952.
Chen Z Concepcion JJ Luo H Hull JF Paul A Meyer TJ 《Journal of the American Chemical Society》2010,132(50):17670-17673
The complex [Ru(Mebimpy)(bpy)(OH(2))](2+) [Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine; bpy = 2,2'-bipyridine] and its 4,4'-(PO(3)H(2)CH(2))(2)bpy derivative on oxide electrodes are water oxidation catalysts in propylene carbonate and 2,2,2-trifluoroethanol (TFE) to which water has been added as a limiting reagent. The rate of water oxidation is greatly enhanced relative to that with water as the solvent and occurs by a pathway that is first-order in H(2)O; an additional pathway that is first-order in acetate appears when TFE is used as the solvent. 相似文献
953.
Mei Luo 《Tetrahedron letters》2010,51(42):5577-5580
A series of novel N-metal complexes containing chiral α-ethylphenyl amines was synthesized and they catalyzed asymmetric Henry reactions affording products with high enantioselectivity. 相似文献
954.
Three novel sandwich‐type polyoxotungstates ( 1 – 3 ) were synthesized in good yield using an in‐situ conventional solution synthesis method by reaction in aqueous media below 80 °C. Compounds 1 – 3 represent the first structurally characterized β‐B‐BiW9 sandwich‐type polyoxometalates with triethanolamine cations. All three compounds have the same building unit [(X(H2O)3)2(X0.5W0.5O)2(β‐B‐BiW9O33)2)]10– [X = MnII ( 1 ), CoII ( 2 ), NiII ( 3 )]. The adjacent units of 1 or 2 are joined by Na+ cations in different ways to construct 1D chains or 2D sheets. A 3D supramolecular structure is further formed by hydrogen bond interactions among water molecules and protonated triethanolamine cations. Meanwhile only compound 3 shows a 0D structure. The compounds were characterized by elemental analysis, IR spectroscopy, TG analysis, and single‐crystal X‐ray diffraction. Magnetic measurements on a sample of 1 show the presence of paramagnetic interactions. 相似文献
955.
A series of novel helicid derivatives containing 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidine2(1H)-thione moiety (3a–3f and 4a–4f) were synthesized starting from helicid. The structure of the new compounds were characterized by 1H NMR, IR and HR-MS spectra. The sedative-hypnotic activities of the target compounds were evaluated using the test of spontaneous
locomotor activity in mice. All of the derivatives produced moderate to high activities; in particular, compound 4a presented the most potent sedative-hypnotic effect in comparison to the other derivatives, and derivatives 3a, 3c, 3d, 3e and 3f also showed potent activities. 相似文献
956.
Pengjun Shi Ning Li Peilong Yang Yaru Wang Huiying Luo Yingguo Bai Bin Yao 《Applied biochemistry and biotechnology》2010,162(3):707-718
An α-l-arabinofuranosidase gene, abf51S9, was cloned from Streptomyces sp. S9 and successfully expressed in Escherichia coli BL21 (DE3). The full-length gene consisted of 1,506 bp and encoded 501 amino acids with a calculated mass of 55.2 kDa. The
deduced amino acid sequence was highly homologous with the α-l-arabinofuranosidases belonging to family 51 of the glycoside hydrolases. The recombinant protein was purified to electrophoretic
homogeneity by Ni-NTA affinity chromatography and subsequently characterized. The optimal pH and temperature for the recombinant
enzyme were 6.0 and 60∼65 °C, respectively. The enzyme showed a broad pH range of stability, retaining over 75% of the maximum
activity at pH 5.0 to 11.0. The specific activity, K
m, and V
max with p-nitrophenyl-α-l-arabinofuranoside as substrate were 60.0 U mg−1, 1.45 mM, and 221 μmol min−1 mg−1, respectively. Abf51S9 showed a mild but significant synergistic effect in combination with xylanase on the degradation of
oat-spelt xylan and soluble wheat arabinoxylan substrates with a 1.19- and 1.21-fold increase in the amount of reducing sugar
released, respectively. These favorable properties make Abf51S9 a good candidate in various industrial applications. 相似文献
957.
A DNA fragment containing the entire coding sequence of nitrilase gene was amplified from Rhodococcus rhodochrous tg1-A6 with high nitrilase activity using PCR and sequenced. The open reading frame of the nitrilase gene contains 1,101 base
pairs, which encodes a putative polypeptide of 366 amino acid residues. The nitrilase gene was cloned into an expression vector
pET-28a and expressed in an Escherichia coli strain BL21(DE3). The enzymatic activity of nitrilase, which converts various nitriles to the corresponding carboxylic acids,
was detected to reach 24.5 U/ml at 9 h in the recombinant bacteria. 相似文献
958.
Shirong Yuan Ruo Yuan Yaqin Chai Ying Zhuo Xia Yang Yali Yuan 《Applied biochemistry and biotechnology》2010,162(8):2189-2196
In this work, an enzyme biosensor based on the immobilization of horseradish peroxidase (HRP) on SiO2/BSA/Au/thionine/nafion-modified gold electrode was fabricated successfully. Firstly, nafion was dropped on the surface of
the gold electrode to form a nafion film followed by chemisorption of thionine (Thi) as an electron mediator via the ion-exchange
interaction between the Thi and nafion. Subsequently, the SiO2/BSA/Au composite nanoparticles were assembled onto Thi film through the covalent bounding with the amino groups of Thi. Finally,
HRP was immobilized on the SiO2/BSA/Au composite nanoparticles due to the covalent conjugation to construct an enzyme biosensor. The surface topographies
of the SiO2/BSA/Au composite nanoparticles were investigated by using scanning electronic microscopy. The stepwise self-assemble procedure
of the biosensor was further characterized by means of cyclic voltammetry and chronoamperometry. The enzyme biosensor showed
high sensitivity, good stability and selectivity, a wide linear response to hydrogen peroxide (H2O2) in the range of 8.0 × 10-6 ∼ 3.72 × 10-3 mol/L, with a detection limit of 2.0 × 10-6 mol/L. The Michaelies-Menten constant KMapp K_M^{app} value was estimated to be 2.3 mM. 相似文献
959.
Jian-Ping Zou Sheng-Lian Luo Ming-Jun Li Xin-Hua Tang Qiu-Ju Xing Qiang Peng Guo-Cong Guo 《Polyhedron》2010
A series of lanthanide(III) complexes with chelidamic acid ligand, [Ln(C7H2NO5)·3H2O]n·nH2O (Ln = La (1), Y (2), Sm (3), and Nd (4)), [Gd2(C7H2NO5)3·4H2O]n·2nH2O (5) and [Ce(C7H2NO5)·1.5H2O]n (6), have been synthesized by hydrothermal method and structurally characterized by single-crystal X-ray diffraction. Complexes 1–4 are isostructural and possess 2D framework. Complex 5 contains two different Gd(III) ions linked through carboxylate group to form a 2D framework. Complex 6 exhibits a (44) topology 2D network. The variable-temperature magnetic properties of 3 and 5 have been investigated. Furthermore, the photoluminescent properties of 1, 2, 3, and 5 at room temperature were also studied. 相似文献
960.
Xiaoteng Luo Jingjing Xu John Barford I-Ming Hsing 《Electrochemistry communications》2010,12(4):531-534
This work reports a novel electrochemical PCR detection platform using magnetic particles as a separation tool. A redox-active intercalator, anthraquinonemonosulfonic acid (AQMS), was firstly intercalated into biotin labeled PCR amplicons, and the resulting complex was then captured by streptavidin-coated magnetic particles (MPs) to form AQMS–DNA–MP conjugates. Subsequently, these conjugates were attracted to the bottom of the tube and separated from the solution by applying an external magnetic field, resulting in a significant reduction of the concentration of solution AQMS. The concentration changes of solution AQMS, which reflect the presence and quantity of PCR amplicons, were monitored by differential pulse voltammetry (DPV) on a chip electrode. PCR cycle number-dependent as well as the initial template DNA concentration-dependent performances were investigated. This electrochemistry based PCR detection platform is simple, convenient and inexpensive, and may have potential applications for practical sample monitoring. 相似文献