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991.
Tomoharu Sakai Hiroyuki Nakagawa Shinya Kitagawa Hajime Ohtani 《Analytical sciences》2008,24(6):735-738
Dual-gradient capillary electrochromatography (DG-CEC) was developed to provide superior performance with regard to the separation of ionized analytes; in this method, both the eluent composition and the applied voltage are varied during the separation procedure. As for the gradient in the eluent composition, a shift in the pH is employed to control not only the electrophoretic mobility, but also the retention factor of the analytes. The dual-gradient method was shown to be effective in increasing the resolution and reducing the chromatographic period of ionized analytes. Fourteen kinds of o-phthalaldehyde labeled amino acids were separated within 8 min using DG-CEC with multistage enlargement in the applied voltage. The separation efficiency increased particularly for highly retained amino acids in the dual-gradient, as compared to those in the ordinary single-gradient for the eluent. 相似文献
992.
Tokuji Ikeda Hirosuke Tatsumi Hajime Katano Mizue Wanibuchi Takao Hibi Tsutomu Kajino 《Analytical sciences》2008,24(2):237-241
The thermal stability of a redox enzyme, bilirubin oxidase (BOD), has been quantitatively evaluated by measuring the inactivation kinetics of BOD at several temperatures. The enzyme activity is directly related to the mediated bioelectrocatalytic current for the BOD-catalyzed reduction of O(2). Thus, the inactivation process is measured by the time-dependent decrease in the bioelectrocatalytic current. The results reveal that the inactivation obeys first-order kinetics, whose rate constants (k) are determined at pH 7.0 and at 50 - 70 degrees C. The half life of BOD activity, calculated from the k value at 50 degrees C is 114 min, which is in harmony with the thermal-stability data given in a catalog by Amano Enzyme Inc. The bioelectrocatalysis method allows in situ measurements of the inactivation kinetics in the period of a few minutes at relatively high temperatures. The rate constants show a large temperature dependence, leading to a large Arrhenius activation energy (E(A)) of 221 kJ mol(-1). The activation Gibbs energy (DeltaG(not equal)), activation enthalpy (DeltaH(not equal)), and activation entropy (DeltaS(not equal)) are also determined. 相似文献
993.
Kazutoshi Nose Tatsuo Mizuno Norio Yamane Takaharu Kondo Hajime Ohtani Shuki Araki Takao Tsuda 《Analytical sciences》2005,21(12):1471-1474
Identifying and measuring the ammonia gas that emanates from human skin, which we called skin gas, has been achieved using a modified gas chromatographic system with a nitrogen-selective detector (flame-thermoionic detector: FTD). The skin gas is collected with a home-made sampling probe or bag, which is used to cover the skin surface of a subject's wrist, or a finger, for 5 min. It was proved that ammonia was present in skin gas for healthy persons and patients with hepatic disease. The average amounts of ammonia were 1.7 +/- 0.4 and 2.7 +/- 0.8 ng/cm2; furthermore, there was a significant difference between them (p < 0.05). In addition, the ammonia levels present in skin gas were correlated with that in blood (r = 0.64, p < 0.05). 相似文献
994.
Taro Ueda Takayuki Nagano Hajime Okawa Seiji Takahashi 《Electrochemistry communications》2009,11(8):1654-1656
An amperometric zirconia-based sensor attached with perovskite-type oxide sensing electrode was examined for monitoring NO2 in automobile exhaust. The sensor using La0.6Sr0.4Co0.98Mn0.02O3 showed high response to NO2. The response was almost linear to NO2 concentration in the range between 50 and 800 ppm, and a 90% reaction time to 400 ppm NO2 was less than 20 s. Though the NO2 response of the sensor was slightly affected by the changes in O2 concentrations, it showed still high response in the examined range of 5–21 vol%. 相似文献
995.
Momoko Tanaka Hiromitsu Kiriyama Yoshihiro Ochi Yoshiki Nakai Hajime Sasao Hajime Okada Hiroyuki Daido Paul Bolton Shunichi Kawanishi 《Optics Communications》2009,282(22):4401-4985
We have demonstrated that we can homogenize the spatial profile of a high-energy green laser pulse used for pumping a petawatt scale Ti:sapphire amplifier. The second harmonic of a high-energy, large aperture Nd:glass laser system generates laser emission at a green wavelength with 75 J single pulse energy. Using a diffractive optical element for beam homogenization, we have obtained a highly spatially uniform flat-top second harmonic profile. 相似文献
996.
Xu Feng NI Zhi Quan SHEN* Hajime YASUDA Institute of Polymer Science Zhejiang University Hangzhou Department of Applied Chemistry Faculty of Engineering Hiroshima University Higashi-Hiroshima Japan 《中国化学快报》2001,(9)
Synthesis of polymers with controlled molecular weight and narrow polydispersity is of both fundamental interest and practical importance. In recent years, high molecular weight poly (methyl methacrylate) (PMMA) having an unusually narrow polydispersity has been synthesized by using the unique initiating property of (C5Me5)2LnⅢR (R=H, Me, Ln=Sm, Yb) complexes1,2. Herein we report the results of the first example of the polymerization of methyl methacrylate (MMA) with samarocene complex … 相似文献
997.
Hiroyuki Shirahama Kiyoshi Mizuma Koichi Umemoto Hajime Yasuda 《Journal of polymer science. Part A, Polymer chemistry》2001,39(9):1374-1381
Homopoly(L ‐lactide) and homopoly(D,L ‐lactide) were almost inert for biodegradation with tricine buffer or normal enzymes such as bromelain, pronase, and cholesterol esterase but biodegradable with proteinase K. Significantly enhanced biodegradation was observed when an optically active (R)‐ or (S)‐3‐methyl‐4‐oxa‐6‐hexanolide (MOHEL) unit was introduced into poly(L ‐lactide) [poly(L ‐LA)] or poly(D,L ‐lactide) [poly(D,L ‐LA)] sequences. Poly[L ‐LA‐ran‐(R)‐MOHEL] in molar ratios of 86/14 to 43/57 showed good biodegradability that was independent of crystallinity. The biodegradation of polymers with proteinase K increased in the following order: poly[D,L ‐LA‐ran‐(R)‐MOHEL] > poly[L ‐LA‐ran‐(R)‐MOHEL] > poly[D,L ‐LA‐ran‐(S)‐MOHEL] > poly[L ‐LA‐ran‐(S)‐MOHEL] > poly(R)‐MOHEL > poly(D,L ‐LA). The number‐average molecular weight, molecular weight distribution, glass‐transition temperature, and melting temperature did not change before and after the biodegradation of poly[L ‐LA‐ran‐(R)‐MOHEL], indicating that the degradation occurred from the polymer surface. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1374–1381, 2001 相似文献
998.
Kazuaki Ito Yoshihiro Ohba Takafumi Tamura Tomoaki Ogata Hajime Watanabe Yasumitsu Suzuki Takayuki Hara Yukou Morisawa Tyo Sone 《Journal of heterocyclic chemistry》2001,38(1):293-298
Calixarene analogs containing a thiophene unit in the macrocyclic ring were prepared by a stepwise method. The macrocycles adopt a cone‐like form as the preferred conformation in solution. The induced chemical shift change, nOe experiment, and 1H relaxation time (T1) measurement supported the fact that the macrocycle forms a complex with the N‐methylpyridinium salt. In contrast, O‐tetramethylated macrocycles and linear phenol‐formaldehyde tetramer, could not efficiently include the N‐methylpyridinium salt. 相似文献
999.
Haruko Takechi Yasuo Goto Hajime Takahashi Minoru Machida 《Journal of heterocyclic chemistry》2001,38(2):333-338
4‐(7‐Diethylaminocoumarin‐3‐yl)benzeneisocyanate (DACB‐NCO) was synthesized as a new fluorescent derivatization reagent for alcohols for use in high‐performance liquid chromatography (hplc). Saturated alcohols (C6‐C22) were derivatized in good yields into the corresponding fluorescent DACB‐carbamic esters by treating with DACB‐NCO. The DACB‐carbamic esters of these alcohols were clearly separated on a reversed‐phase hplc column (Inertsil ODS‐2, mobile phase: methanol‐water, excitation wavelength 402 nm; emission wavelength 488 nm). The detection limit (S/N = 3) of cetyl alcohol, as a test compound, was 5 fmol/10 μl. 相似文献
1000.
Dr. Masayuki Iguchi Dr. Naoya Onishi Dr. Yuichiro Himeda Dr. Hajime Kawanami 《Chemphyschem》2019,20(10):1296-1300
Aiming to develop a highly effective and durable catalyst for high-pressure H2 production from dehydrogenation of formic acid (DFA), the ligand effect on the catalytic activity and stability of Cp*Ir (Cp*:pentamethylcyclopentadienyl anion) complexes were investigated using 5 different kinds of N,N’-bidentate ligands (bipyridine, biimidazoline, pyridyl-imidazoline, pyridyl-pyrazole and picolinamide). The Ir complex with biimidazoline ligand exhibited the highest catalytic activity, but deactivation occurred readily at high pressure. The pyridine moiety in the ligand can enhance the stability of Ir complex catalysts for the high-pressure reaction. The Ir complex catalyst containing pyridyl-imidazoline ligand showed the high activity and best stability under the high-pressure conditions. 相似文献