全文获取类型
收费全文 | 1053篇 |
免费 | 22篇 |
国内免费 | 7篇 |
专业分类
化学 | 770篇 |
晶体学 | 24篇 |
力学 | 20篇 |
数学 | 61篇 |
物理学 | 207篇 |
出版年
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 18篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 17篇 |
2015年 | 12篇 |
2014年 | 30篇 |
2013年 | 49篇 |
2012年 | 64篇 |
2011年 | 79篇 |
2010年 | 40篇 |
2009年 | 39篇 |
2008年 | 84篇 |
2007年 | 70篇 |
2006年 | 68篇 |
2005年 | 46篇 |
2004年 | 38篇 |
2003年 | 47篇 |
2002年 | 38篇 |
2001年 | 22篇 |
2000年 | 17篇 |
1999年 | 10篇 |
1998年 | 13篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 20篇 |
1993年 | 12篇 |
1992年 | 7篇 |
1991年 | 12篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 23篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 13篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1973年 | 3篇 |
排序方式: 共有1082条查询结果,搜索用时 15 毫秒
1.
Hiroshi Tanaka Toru Masuko Keisuke Homma Saburo Okajima 《Journal of polymer science. Part A, Polymer chemistry》1969,7(7):1997-2006
Polypropylene films of various isotacticities and crystallinities were stretched biaxially in one step in air at 140–152°C or polyaxially in poly(ethylene glycol) at 130–160°C, and the morphological changes were studied by electron microscopy (replica). In the initial stage of stretching, with vA = 1.4, the spherulites of one of the films used for the experiment were broken both from the centers and boundaries, and those of another film were broken mainly from the center. This difference in the deformation behavior seems to be characteristic of the film properties and independent of the method of stretching, although the factors involved are still unknown. On further stretching (vA = 22), well annealed spherulites were broken into many small blocklike fragments with unfolded fibrils running among them, particularly at the low stretching temperature (140°C), and fibrillation proceeded at the expense of the residual fragments. In the case of quenched or slightly crystallized material, the fragments were dendritic and divided into finer and finer fibrils on stretching. At elevated temperature, however, even for well annealed spherulites, the deformation behavior resembles that of the quenched material, and at a high degree of stretching the spherulites take on the fibrillar net structure in every case. In films containing a high amount of atactic fraction, radial, tangential, and boundary cracking occurred more easily, and broad fibrils were observed across the cracks. 相似文献
2.
Toru Takagishi Katsushige Takami Nobuhiko Kuroki 《Journal of polymer science. Part A, Polymer chemistry》1974,12(1):191-200
The binding of 4′-dibutylaminoazobenzene-4-sulfonate anion (butyl orange) by bovine serum albumin has been examined quantitatively by an equilibrium dialysis method at 5, 10, 15, 20, 25, and 35°C. The first binding constants and the thermodynamic parameters for the formation of the first dye anion-protein complex have been calculated. The peculiar temperature dependence of the first binding constant could be observed. That is, the value of the first binding constant increases with increasing temperature until it reaches a maximum value at approximately 18°C and then decreases with raising temperature. Accordingly, this binding process is exothermic above 18°C and is endothermic below 18°C. Near 18°C the process exhibits athermal reaction. From the thermodynamic data obtained, it is evident that the favorable free energy of the binding is accompanied by an entropy gain and that the enthalpies of the binding vary from a positive (unfavorable) value below 18°C to a negative (favorable) one above 18°C. Furthermore an apparent temperature dependence of the thermodynamic functions was observed. That is, ΔF° becomes larger in absolute magnitude as the temperature increases. The positive quantity of ΔS° tends to decrease with increasing temperature. All these facts can be interpreted satisfactorily in terms of hydrophobic interactions between hydrophobic portions of the dye and nonpolar parts of the albumin. 相似文献
3.
Yoshihiko Ito Yoshinori Inubushi Toru Sugaya Takeo Saegusa 《Journal of organometallic chemistry》1977,137(1):1-9
Reaction of carboxamides with Cu2O in the presence of t-butyl isocyanide gave new chelated copper(I) complexes, which probably are formed by the insertion of t-butyl isocyanide into the coppernitrogen bond of copper(I) amide isonitrile complexes, which were initially produced from the carboxamides and Cu2Ot-butyl isocyanide complex. The same chelated copper(I) complexes were prepared more readily by the reaction of the corresponding N-trimethylsilyl-carboxamides with Cu2Ot-butyl isocyanide complex. Reactions of the copper(I) complexes thus obtained with alkylating agents, such as alkyl halides, alkyl tosylates and triethyloxonium tetrafluoroborate, also were described. 相似文献
4.
An on-line purification method for catecholamines was studied using a flow system equipped with an alumina microcolumn. The procedure involves catecholamine adsorption, column washing and catecholamine elution steps. The system is designed not to decompose catecholamines under alkaline conditions in the adsorption step. Flow-rates and times for different solutions delivered in each step (alkaline buffer for adsorption, water for washing and an acidic solution for elution), column length and sample volume to be loaded were systematically investigated by liquid chromatography. Under optimum conditions, norepinephrine, epinephrine, dopamine and 3,4- dihydroxybenzylamine (internal standard) can be purified with recoveries of ? 90% within 11 min with manual operation. This method was efficiently applied to urine samples and the results indicate the possibility that catecholamines in biological samples are automatically purified. 相似文献
5.
The dual Meissner effect is observed without monopoles in quenched SU(2) QCD with Landau gauge fixing. Magnetic displacement currents that are time-dependent Abelian magnetic fields act as solenoidal currents squeezing Abelian electric fields. Monopoles are not always necessary for the dual Meissner effect. A mean-field calculation suggests that the dual Meissner effect through the mass generation of the Abelian electric field is related to a gluon condensate A(a)(mu)A(a)(mu) not equal 0 of mass dimension 2. 相似文献
6.
Toru Sasahara 《Journal of Geometry and Physics》2010,60(6-8):884-895
We classify biminimal Lagrangian surfaces in complex space forms under the condition that the integral curves of Maslov vector field are geodesics. 相似文献
7.
8.
Kimio Asaka Yoshihito Hirano Kenji Tatsumi Kumio Kasahara Toru Tajime 《Optical Review》1998,5(5):310-314
We propose a new detection method for a pseudo-random frequency modulation continuous wave (RM-CW) coherent lidar. The feature of this method is modulation of local beam with a time delayed pseudo-random sequence. Heterodyne detection and correlation detection between the received beam and the local beam are simultaneously carried out in an optical field. In the RM-CW coherent lidar using the optical field correlation detection method, the received equipment is greatly simplified. We carried out preliminary experiments and demonstrated that the new method is effective for detection of a CW coherent lidar. 相似文献
9.
A photo-induced radical pair of FADH· and Y8· and in BLUF protein SyPixD was studied by pulsed electron paramagnetic resonance (EPR) spectroscopy. Blue light illumination
at 150 K for 30 min followed by cooling to 50 K during illumination induced the stable radical pair. The EPR signal has been
characterized by a Pake doublet signal with complete S = 1 spin state. The radical pair was utilized as a probe to analyze the oligomer of SyPixD. The relative arrangement of PixD
proteins in the complex was investigated by pulsed electron–electron double resonance (PELDOR) with the orientation selection.
Based on the decameric structure in the crystal, the possible structure for the PELDOR results was discussed. 相似文献
10.
Kenzo Miyazaki Toru Fukatsu Ichiro Yamashita Toshifumi Hasama Kawakatsu Yamada Takuzo Sato 《Applied physics. B, Lasers and optics》1991,52(1):1-7
Improvements in output pulse energy and efficiency of a conventional capacitor-transfer-type discharge excimer laser with automatic preionization have been achieved by extending the discharge volume and resulting moderate pumping of the active medium. The discharge laser produces a pulse energy of more than 1 J for XeCl, KrF, and ArF lasers in square beams of about 2×2 cm2, and the maximum overall efficiency observed is 2.9% for XeCl, 3.2% for KrF and 1.8% for ArF. The laser device has been involved in a picosecond ( 32 ps) XeCl laser amplification system, and was operated as an amplifier at a repetitive frequency of 10 Hz. Saturation fluence for XeCl laser was measured to be 1.4 mJ/cm2, and the picosecond pulse energy of 40 mJ was extracted from the amplifier.On leave from Ebara Corp., 6-6-7, Ginza, Chuo-ku, Tokyo 104, JapanOn leave from Mitsubishi Heavy Industries, LTD., 4-6-22, Kan-on shinmachi, Nishi-ku, Hiroshima 733, Japan 相似文献