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排序方式: 共有1314条查询结果,搜索用时 62 毫秒
911.
Teppei KikuchiRyo Kasuya Shota EndoAkira Nakamura Toshiyuki TakaiNils Metzler-Nolte Kazuyuki TohjiJeyadevan Balachandran 《Journal of magnetism and magnetic materials》2011,323(10):1216-1222
An aqueous magnetic suspension was prepared by dispersing amphiphilic co-polymer-coated monodispersed magnetite nanoparticles synthesized through thermal decomposition of iron acetylacetonate (Fe(acac)3) in a mixture of oleic acid and oleylamine. The average diameter of narrow-size-distributed magnetite nanoparticles varied between 5 and 12 nm depending on the experimental parameters such as reaction temperature, metal salt concentration and oleic acid/oleylamine ratio. Though the as-synthesized particles were coated with oleate and were dispersible in organic solvent, their surfaces were modified using amphiphilic co-polymers composed of poly(maleic anhydride-alt-1-octadecene) and polyethylene glycol-methyl ether and made dispersible in water. Infrared spectra of the sample indicated the existence of −COOH groups on the surface for further conjugation with biomolecules for targeted cancer therapy. 相似文献
912.
Tanaka M Nakamura K Iwado T Sato T Okada M Sue K Iwamura H Hiaki T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(2):606-612
Cyclotrimerization of 1‐phenyl‐2‐propyn‐1‐one in pressurized hot water gave 1,3,5‐tribenzoylbenzene in one pot in 65 % yield after 7 min at 200 °C, or in 74 % yield after 60 min at 150 °C. The reaction did not take place in the absence of water, and added base promoted the reaction at 250 °C, suggesting a mechanism of three‐consecutive Michael addition reactions. The reaction rates increased with temperature, but the yield of 1,3,5‐tribenzoylbenzene decreased at the expense of formation of acetophenone as a side product at higher temperatures. p‐Methyl and p‐chloro‐substituents on the phenyl ring retarded and enhanced the reaction, respectively. A mechanism involving the enol of benzoylacetaldehyde at a branching point of the pathway leading to 1,3,5‐tribenzoylbenzene and acetophenone was suggested. 相似文献
913.
Eiichi Sato Yasuyuki Oda Abulajiang Abudurexiti Osahiko Hagiwara Hiroshi Matsukiyo Akihiro Osawa Toshiyuki Enomoto Manabu Watanabe Shinya Kusachi Shigeaki Sugimura Haruyuki Endo Shigehiro Sato Akira Ogawa Jun Onagawa 《Radiation Physics and Chemistry》2011,80(12):1327-1332
6 Mcps photon counting was carried out using a detector consisting of a 1.0 mm-thick LSO [Lu2(SiO4)O] single-crystal scintillator and an MPPC (multipixel photon counter) module in an X-ray computed tomography (CT) system. The maximum count rate was 6 Mcps (mega counts per second) at a tube voltage of 100 kV and a tube current of 0.91 mA. Next, a photon-counting X-ray CT system consists of an X-ray generator, a turntable, a scan stage, a two-stage controller, the LSO–MPPC detector, a counter card (CC), and a personal computer (PC). Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan with a scan velocity of 25 mm/s. The pulses of the event signal from the module are counted by the CC in conjunction with the PC. The exposure time for obtaining a tomogram was 600 s at a scan step of 0.5 mm and a rotation step of 1.0°, and photon-counting CT was accomplished using gadolinium-based contrast media. 相似文献
914.
Maruyama T Onda K Suzuki T Hayakawa M Takahashi T Matsui T Takasu T Nagase I Ohta M 《Chemical & pharmaceutical bulletin》2012,60(5):647-658
In the search for potent and selective human β3-adrenergic receptor (AR) agonists as potential drugs for use in treating obesity and non-insulin dependent (type 2) diabetes, a series of N-phenyl-(2-aminothiazol-4-yl)acetamides with phenoxypropanolamine moiety were prepared and their biological activities against human β3-, β2-, and β1-ARs were evaluated. Among these compounds, N-phenyl-(2-phenylaminothiazol-4-yl)acetamide (4 g), N-phenyl-(2-benzylaminothiazol-4-yl)acetamide (4j), and N-phenyl-[2-(3-methoxyphenyl)aminothiazol-4-yl]acetamide (6g) derivatives showed potent agonistic activity against the β3-AR with functional selectivity over the β1- and β2-ARs. In addition, these compounds exhibited significant hypoglycemic activity in a rodent model of diabetes. 相似文献
915.
Fahrettin Gogtas Ezman Karabulut Tomokazu Tanaka Toshiyuki Takayanagi Rukiye Tutuk 《International journal of quantum chemistry》2012,112(11):2348-2354
The H + F2 → HF + F reaction on ground state potential energy surface is investigated using the quantum mechanical real wave packet and Flux analysis method based on centrifugal sudden approximation. The initial state selected reaction probabilities for total angular momentum J = 0 have been calculated by both methods while the probabilities for J > 0 have been calculated by Flux analysis method. The initial state selected reaction probabilities, integral cross sections and rate coefficients have been calculated for a broad range of collision energy. The results show a large rotational enhancement of the reaction probability. Some resonances were seen in the state‐to‐state reaction probabilities while state‐to‐all reaction probabilities and the reaction cross section do not manifest any oscillations and the initial state selected reaction rate constants are sensitive to the temperature. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 相似文献
916.
Two new aromatic compounds (1, 2), new d-arabinitol ester (3), and two known compounds (4, 5) were isolated from mushroom Hericium erinaceum. The structures of 1–5 were elucidated on the basis of spectral data. Compounds 1, 2, 4, and 5 exhibited α-glucosidasae inhibitory activity. 相似文献
917.
Ken-ichi Nakashima Masayoshi Oyama Tetsuro Ito Yukihiro Akao Joko Ridho Witono Dedy Darnaedi Toshiyuki Tanaka Jin Murata Munekazu Iinuma 《Tetrahedron》2012,68(10):2421-2428
Six novel quinolinone alkaloids bearing a phenylpropanoid or a coumarin moiety, named melicodenines C–H (1–6), two new cinnamyl alcohol derivatives, named melicodins A (7) and B (8), and a new coumarinolignan, named melicodin C (9), were isolated from the leaves of Melicope denhamii (Seem.) T. G. Hartley. Their structures were established by spectroscopic analyses including extensive 2D-NMR experiments. Compounds 1–5 and 9 possess a cyclobutane ring and are hypothetically produced by a [2+2] cycloaddition, whereas compound 6 is presumed to form through a Diels–Alder cycloaddition followed by the elimination of an acetone molecule. Ten quinolinone alkaloids (1–6, 10–13) and a coumarinolignan (9) were tested for anti-proliferative activity against DLD-1 human colon cancer cells. Melicodenine G (5) showed the most potent inhibitory activity, causing the induction of apoptosis with an IC50 value of 9.4±0.3 μM. 相似文献
918.
Toshiyuki Kamei 《Tetrahedron letters》2012,53(30):3894-3896
Scandium triflate-catalyzed iodination of 2,2′-dimethoxy-1,1′-binaphthyl with 2 equiv of 1,3-diiodo-5,5-dimethylhydantoin (DIH) proceeded to give 6,6′-diiodo-2,2′-dimethoxy-1,1′-binaphtyl in 98% yield and subsequent deprotection of methyl groups provided 6,6′-diiodo-1,1′-binaphthol, which is a useful ligand or reagent for many enantioselective transformations. Use of 2 equiv of NIS in place of DIH in the presence of scandium triflate, however, did not successfully yield 6,6′-diiodo-2,2′-dimethoxy-1,1′-binaphtyl, indicating that one of two types of iodine atoms in DIH is more reactive toward the iodination than iodine in NIS. 相似文献
919.
A Yoshida M Akaiwa T Asakawa Y Hamashima S Yokoshima T Fukuyama T Kan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(36):11192-11195
When life gives you lemons: An efficient and convergent enantioselective total synthesis of (-)-lemonomycin, which shows potent activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VREF), is presented. The key reaction steps are a Hosomi-Sakurai-type cyclization, a thermodynamically controlled Pictet-Spengler reaction, and a glycosidation reaction with lemonose. 相似文献
920.
Hisaki I Sasaki T Tohnai N Miyata M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(33):10066-10073
A twofold helix (2(1) helix) is an essential motif in approximately 70?% of organic crystals. Although handedness of 2(1) helix has not been discussed from a mathematical viewpoint, we noticed that the handedness can be defined by considering the molecular shape and manner of assembly. Herein we propose the supramolecular-tilt-chirality (STC) method to define the handedness, and illustrate it by way of some examples. We believe that establishment of the systematic rules for supramolecular chirality will contribute to the progression of supramolecular chemistry and material science. 相似文献