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311.
Shinji Kishimoto Yuta Tsunematsu Shinichi Nishimura Yutaka Hayashi Akira Hattori Hideaki Kakeya 《Tetrahedron》2012,68(27-28):5572-5578
Tumescenamide C, a new cyclic lipodepsipeptide, was isolated from a culture broth of an actinomycete Streptomyces sp. KUSC_F05. Tumescenamide C was a congener of tumescenamides A and B, representing a sixteen-membered ring system, consisting of two proteinogenic and three non-proteinogenic amino acids, to which a methyl-branched fatty acid was attached. The planar structure was determined by spectroscopic analysis, while its absolute stereochemistry was determined by chemical degradation and asymmetric synthesis. Tumescenamide C exhibited antimicrobial activity with high selectivity against Streptomyces species. 相似文献
312.
The relationship is investigated for QM/MM (quantum-mechanical/molecular-mechanical) systems between the fluctuations of the electronic state of the QM subsystem and of the solvation effect due to the QM-MM interaction. The free-energy change due to the electron-density fluctuation around its average is highlighted, and is evaluated through an approximate functional formulated in terms of distribution functions of the many-body coupling (pairwise non-additive) part of the QM-MM interaction energy. A set of QM/MM simulations are conducted in MM water solvent for QM water solute in ambient and supercritical conditions and for QM glycine solute in the neutral and zwitterionic forms. The variation of the electronic distortion energy of the QM solute in the course of QM/MM simulation is then shown to be compensated by the corresponding variation of the free energy of solvation. The solvation free energy conditioned by the electronic distortion energy is further analyzed with its components. It is found that the many-body contribution is essentially equal between the free energy and the average sum of solute-solvent interaction energy. 相似文献
313.
H Nagase S Imaide T Yamada S Hirayama T Nemoto N Yamaotsu S Hirono H Fujii 《Chemical & pharmaceutical bulletin》2012,60(8):945-948
On the basis of the three-dimensional pharmacophore model of opioid κ agonists, we simplified the structure of nalfurafine (selective κ agonist) to find the essential structural moieties for binding the opioid receptors, especially κ receptor type. As a result, we found that the trans-fused decahydroisoquinoline derivatives without a phenol ring bound the opioid receptor in micromolar order and that both the amide side chain and the nitrogen substituted by the cyclopropylmethyl group were indispensable moieties for eliciting the κ selectivity. The simple decahydroisoquinoline without amide side chain also bound the opioid receptor without receptor type selectivity, suggesting that the message-address concept would be applicable to even these simple derivatives. These findings that the simple decahydroisoquinoline derivatives showed the affinities for the opioid receptors, especially some of the compounds showed κ selectivity, are the first example in the opioid field. 相似文献
314.
Nobuyuki Kawahara Eiji Tomita Takuya Kadowaki Tetsuya Honda Hideaki Katashiba 《Experiments in fluids》2010,49(4):925-936
Vaporized fuel concentration in a spray-guided direct-injection spark-ignition (SG-DISI) engine was measured using an optical
sensor installed in a spark plug. A laser infrared absorption method was applied to quantify the instantaneous gasoline concentration
near the spark plug. This paper discusses the feasibility of obtaining in situ air–fuel ratio measurements with this sensor
installed inside an SG-DISI engine cylinder. First, the effects of the spray plume from a multi-hole injector on the vaporized
fuel concentration measurements near the spark-plug sensor were examined using a visible laser. We determined the best position
for the sensor in the engine, which was critical due to the spray and vapor plume formation. Then, a 3.392-μm He–Ne laser
that coincided with the absorption line of the hydrocarbons was used as a light source to examine the stratified mixture found
during ultra-lean engine operation. A combustible mixture existed around the spark plug during the injection period when a
preset air–fuel ratio of 45.0 was used with different fuel injection timings and net mean effect pressure conditions. The
effects of the orientation of the spark plug on the measured results and ignitability of the SG-DISI engine were examined.
Orienting the spark plug vertically to one of the spray plumes provided more accurate results and better engine reliability.
The study demonstrated that it was possible to qualify the air–fuel ratio near the spark plug during the injection period
using the developed spark-plug sensor in an SG-DISI engine. 相似文献
315.
Yosuke Kataoka 《Journal of Molecular Liquids》2001,90(1-3):35-43
Molecular dynamics simulations on Lennard-Jones mixture in the supercritical region are performed. The number of the molecules in the unit cell is 23328 and the mole fraction is 0.5. The concentration fluctuations near the critical point are large compared to the ideal mixing. The mutual diffusion coefficient normalized by the self-diffusion coefficient has a small value near the critical density because of the large concentration fluctuation. The heat capacity, partial molar volume and correlation lengths of density and concentration in the supercritical region are compared with those at the normal density. 相似文献
316.
Hideaki Fujiwara Atsuomi Kimura Yasuhiro Yanagawa Takashi Kamiya Mineyuki Hattori Takashi Hiraga 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2001,150(2):156
Size dependency of the relaxation time T1 was measured for laser-polarized 129Xe gas encapsulated in different sized cavities made by glass bulbs or gelatin capsules. The use of laser-polarized gas enhances the sensitivity a great deal, making it possible to measure the longer 129Xe relaxation time in quite a short time. The size dependency is analyzed on the basis of the kinetic theory of gases and a relationship is derived in which the relaxation rate is connected with the square inverse of the diameter of the cavity. Such an analysis provides a novel parameter which denotes the wall effect on the relaxation rate when a gas molecule collides with the surface once in a second. The relaxation time of 129Xe gas is also dependent on the material which forms the cavity. This dependency is large and the relaxation study using polarized 129Xe gas is expected to offer important information about the state of the matter of the cavity wall. 相似文献
317.
Shigekazu Ito Hideaki Miyake Hiroki Sugiyama Masaaki Yoshifuji 《Heteroatom Chemistry》2005,16(5):357-360
Kinetically stabilized 2‐lithio‐1‐(2,4,6‐tri‐t‐butylphenyl)‐1‐phosphapropene was allowed to react with a bulky phosphaalkyne Mes*CP (Mes* = 2,4,6‐t‐Bu3C6H2) followed by quenching with iodomethane or benzyl bromide to give the corresponding 1,3‐diphosphabuta‐1,3‐dienes. The presence of the bulky Mes* group on the 1‐phosphorus atom prevents intramolecular [2+2] cyclization and gave the PC PC skeleton, whereas Mes*CP reacted with half an equivalent of nucleophile to afford the PCPC four‐membered ring compounds. X‐ray crystallography of 4‐benzyl‐1,3‐diphosphabuta‐1,3‐diene confirmed the molecular structure showing conjugation on the 1,3‐diphosphabuta‐1,3‐diene moiety. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:357–360, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20104 相似文献
318.
Prof. Dr. Kennosuke Itoh Shun-ichi Nagao Prof. Dr. Ken Tokunaga Dr. Shigeto Hirayama Dr. Fumika Karaki Dr. Takaaki Mizuguchi Dr. Kenichiro Nagai Noriko Sato Dr. Mitsuaki Suzuki Prof. Dr. Masashi Hashimoto Prof. Dr. Hideaki Fujii 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(16):5171-5179
1,2,3,4-Tetrahydroquinolines should be applicable to the development of new pharmaceutical agents. A facile synthesis of 1,2,3,4-tetrahydroquinolines that is achieved by a photoinduced formal [4+2] cycloaddition reaction of acyclic α,β-unsaturated amides and imides with N,N-dialkylanilines under visible-light irradiation, in which a new IrIII complex photosensitizer, a thiourea, and an oxidant act cooperatively in promoting the reaction, is reported. The photoreaction enables the synthesis of a wide variety of 1,2,3,4-tetrahydroquinolines, while controlling the trans/cis diastereoselectivity (>99:1) and constructing contiguous stereogenic centers. A chemoselective cleavage of an acyclic imide auxiliary is demonstrated. 相似文献
319.
Sanae A. Ishijima Lester Clowney Hideaki Koike Masashi Suzuki 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2004,80(1):22
In the crystal the archaeal feast/famine regulatory protein pot0434017 (FL11) forms helical cylinders, each extending along the c axis and densely packed with a hexagonal symmetry in the a/b plane. By applying cryo-electron microscopy to protein solutions yielding crystals, with selectively focussing zero-loss electrons accelerated at 200 KV, two types of regular objects were observed, hexagonal (i.e. projections of crystals to their a/b planes) or rectangular (i.e. projections onto planes perpendicular to a/b). The two types of images are different in the ranges of sizes, suggesting that the crystallization might initiate by forming a hexagonal sheet on the a/b plane, subsequently extending along the c axis. Some other images obtained were intermediate between regular and amorphous, suggesting that some crystals were growing inside amorphous precipitates by rearranging the protein molecules, and that some larger crystals were growing by absorbing smaller amorphous precipitates. Tubes running parallel to each other were also observed in pieces of thin films. These tubes have hollows in their centers, and their lateral arrangement with a periodicity of ~150 Å and the presence of a helical component ~50 Å suggest that they are projections of the helical cylinders, forming mono-layers on the a/c or b/c planes. 相似文献
320.