全文获取类型
收费全文 | 1280篇 |
免费 | 36篇 |
国内免费 | 7篇 |
专业分类
化学 | 914篇 |
晶体学 | 15篇 |
力学 | 17篇 |
数学 | 153篇 |
物理学 | 224篇 |
出版年
2022年 | 9篇 |
2021年 | 5篇 |
2020年 | 9篇 |
2019年 | 10篇 |
2018年 | 5篇 |
2017年 | 19篇 |
2016年 | 26篇 |
2015年 | 18篇 |
2014年 | 26篇 |
2013年 | 64篇 |
2012年 | 47篇 |
2011年 | 80篇 |
2010年 | 38篇 |
2009年 | 49篇 |
2008年 | 68篇 |
2007年 | 88篇 |
2006年 | 83篇 |
2005年 | 93篇 |
2004年 | 78篇 |
2003年 | 62篇 |
2002年 | 65篇 |
2001年 | 17篇 |
2000年 | 24篇 |
1999年 | 20篇 |
1998年 | 13篇 |
1997年 | 18篇 |
1996年 | 14篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1992年 | 16篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 20篇 |
1984年 | 17篇 |
1983年 | 13篇 |
1982年 | 16篇 |
1981年 | 13篇 |
1980年 | 19篇 |
1979年 | 16篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1976年 | 9篇 |
1975年 | 14篇 |
1974年 | 9篇 |
1973年 | 8篇 |
1971年 | 4篇 |
排序方式: 共有1323条查询结果,搜索用时 15 毫秒
141.
Akira Hasegawa Takao Nagahama Hitoshi Ohki Kenji Hotta Hideharu Ishida Makoto Kiso 《Journal of carbohydrate chemistry》2013,32(3):493-498
Development of an efficient α-glycoside synthesis of sialic acids is critically significant for the syntheses of sialoglycoconjugates, especially gangliosides which carry important biological functions1 in biological systems. Previously, we demonstrated2 a new α-glycosylation of sialic acids by use of dimethyl(methylthio)sulfonium triflate (DMTST)3 as the glycosyl promoter, the suitably protected glycosyl acceptors and the methyl 2-thioglycoside 1 of N-acetylneuraminic acid (Neu5Ac) as the donor in acetonitrile under kinetically controlled conditions, and accomplished4 the syntheses of a variety of gangliosides and their analogs. 相似文献
142.
143.
Akihito Kitajima Takeshi Kashirajima Takao Minamizawa Hiroyasu Sato Kazuo Iwaki Taisuke Ueda Yoshio Kimura Toshimasa Toyo'oka Tamio Maitani Rieko Matsuda Yuzuru Hayashi 《Analytical sciences》2007,23(9):1077-1080
The stochastic properties of baseline noise in HPLC systems with a UV photo-diode array, photo-multiplier and gamma-ray detector were examined by dividing the noise into auto-correlated random process (Markov process) and an independent process (white noise). The present work focused on the effect of the stochastic noise properties on a theoretical estimation of the standard deviation (SD) of area measurements in instrumental analyses. An estimation theory, called FUMI theory (Function of Mutual Information), was taken as an example. A computer simulation of noise was also used. It was shown that the reliability (confidence intervals) of theoretical SD estimates mainly depends on the following factors: the ratio of the white noise and Markov process occurring in the baselines; the number of data points used for the estimation; the width of a target peak for which the SD is estimated. 相似文献
144.
Takao Watanabe 《Monatshefte für Mathematik》2006,61(5):155-172
We generalize the notion of successive minima, Minkowski’s second theorem and Siegel’s lemma to a free module over a simple
algebra whose center is a global field. 相似文献
145.
Takao Sano 《Heat and Mass Transfer》1973,6(2):108-113
Exact asymptotic expansions for heat transfer in laminar forced flow against a non-isothermal rotating disk are obtained for large and small Prandtl numbers using a perturbation method. The surface temperature of the disk is assumed to vary according to a power law with the radial distance. The results point out the erroneous terms in the existing asymptotic solutions and give the further higher order corrections to them.
Zusammenfassung Mit Hilfe einer Störungsmethode werden exakte asymptotische Entwicklungen für den Wärmeübergang in laminarer Zwangskonvektion gegen eine nichtisotherme rotierende Scheibe für kleine und große Prandtl-Zahlen erhalten. Die Oberflächentemperatur soll nach einem Potenzgesetz vom Radius abhängen. Die Ergebnisse zeigen die Fehler in den bisherigen Lösungen auf und geben die Korrekturen höherer Ordnung.相似文献
146.
147.
Hideki Shimura Ryota Tanaka Yoshiaki Shimada Kazuo Yamashiro Nobutaka Hattori Takao Urabe 《BMC biochemistry》2017,18(1):14
Background
Peptides with cytoprotective functions, including antioxidants and anti-infectives, could be useful therapeutics. Carnosine, β-alanine-histidine, is a dipeptide with anti-oxidant properties. Tripeptides of Ala-His-Lys, Pro-His-His, or Tyr-His-Tyr are also of interest in this respect.Results
We synthesized several histidine-containing peptides including glycine or alanine, and tested their cytoprotective effects on hydrogen peroxide toxicity for PC12 cells. Of all these peptides (Gly-His-His, Ala-His-His, Ala-His-Ala, Ala-Ala-His, Ala-Gly-His, Gly-Ala-His (GAH), Ala-His-Gly, His-Ala-Gly, His-His-His, Gly-His-Ala, and Gly-Gly-His), GAH was found to have the strongest cytoprotective activity. GAH decreased lactate dehydrogenase (LDH) leakage, apoptosis, morphological changes, and nuclear membrane permeability changes against hydrogen peroxide toxicity in PC12 cells. The cytoprotective activity of GAH was superior to that of carnosine against hydrogen peroxide toxicity in PC12 cells. GAH also protected PC12 cells against damage caused by actinomycin D and staurosporine. Additionally, it was found that GAH also protected SH-SY5Y and Jurkat cells from damage caused by hydrogen peroxide, as assessed by LDH leakage.Conclusion
Thus, a novel tripeptide, GAH, has been identified as having broad cytoprotective effects against hydrogen peroxide-induced cell damage.148.
We introduce themulti-poly-Bernoulli numbers and polynomialswith a q parameter, which are generalizations of the poly-Bernoulli numbers and polynomials with a q parameter, respectively.We give several combinatorial identities and properties of these new numbers and polynomials. 相似文献
149.
Takao Komatsu 《Periodica Mathematica Hungarica》2017,75(2):302-314
For an integer k, define poly-Euler numbers of the second kind \(\widehat{E}_n^{(k)}\) (\(n=0,1,\ldots \)) by When \(k=1\), \(\widehat{E}_n=\widehat{E}_n^{(1)}\) are Euler numbers of the second kind or complimentary Euler numbers defined by Euler numbers of the second kind were introduced as special cases of hypergeometric Euler numbers of the second kind in Komatsu and Zhu (Hypergeometric Euler numbers, 2016, arXiv:1612.06210), so that they would supplement hypergeometric Euler numbers. In this paper, we study generalized Euler numbers of the second kind and give several properties and applications.
相似文献
$$\begin{aligned} \frac{{\mathrm{Li}}_k(1-e^{-4 t})}{4\sinh t}=\sum _{n=0}^\infty \widehat{E}_n^{(k)}\frac{t^n}{n!}. \end{aligned}$$
$$\begin{aligned} \frac{t}{\sinh t}=\sum _{n=0}^\infty \widehat{E}_n\frac{t^n}{n!}. \end{aligned}$$
150.
Periodic mesoporous organosilicas (PMOs) prepared by surfactant-directed polycondensation of bridged organosilane precursors are promising for a variety of next-generation functional materials, because their large surface areas, well-defined nanoporous structures and the structural diversity of organosilica frameworks are advantageous for functionalization. This critical review highlights the unique structural features of PMOs and their expanding potential applications. Since the early reports of PMOs in 1999, various synthetic approaches, including the selection of hydrolytic reaction conditions, development of new precursor compounds, design of templates and the use of co-condensation or grafting techniques, have enabled the hierarchical structural control of PMOs from molecular- and meso-scale structures to macroscopic morphology. The introduction of functional organic units, such as highly fluorescent π-conjugates and electroactive species, into the PMO framework has opened a new path for the development of fluorescent systems, sensors, charge-transporting materials and solid-state catalysts. Moreover, a combinational materials design approach to the organosilica frameworks, pore wall surfaces and internal parts of mesopores has led to novel luminescent and photocatalytic systems. Their advanced functions have been realized by energy and electron transfer from framework organics to guest molecules or catalytic centers. PMOs, in which the precise design of hierarchical structures and construction of multi-component systems are practicable, have a significant future in a new field of functional materials (93 references). 相似文献