全文获取类型
收费全文 | 325篇 |
免费 | 12篇 |
专业分类
化学 | 184篇 |
晶体学 | 3篇 |
力学 | 4篇 |
数学 | 42篇 |
物理学 | 104篇 |
出版年
2023年 | 12篇 |
2022年 | 7篇 |
2021年 | 11篇 |
2020年 | 6篇 |
2019年 | 9篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 14篇 |
2014年 | 17篇 |
2013年 | 23篇 |
2012年 | 38篇 |
2011年 | 27篇 |
2010年 | 12篇 |
2009年 | 15篇 |
2008年 | 20篇 |
2007年 | 20篇 |
2006年 | 8篇 |
2005年 | 18篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 1篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1988年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1965年 | 1篇 |
1939年 | 2篇 |
1938年 | 1篇 |
排序方式: 共有337条查询结果,搜索用时 15 毫秒
21.
K. V. Giri P. N. Bhargava H. Mauban R. J. Bruce und P. G. Denley 《Fresenius' Journal of Analytical Chemistry》1939,118(7-8):279-281
Ohne Zusammenfassung 相似文献
22.
Venkat R. Donuru Giri K. Vegesna Singaravelu Velayudham Ge Meng Haiying Liu 《Journal of polymer science. Part A, Polymer chemistry》2009,47(20):5354-5366
Novel deep‐red emissive poly(2,6‐BODIPY‐ethynylene)s bearing dodecyl side chains (polymers A , B , and C ) have been prepared by palladium‐catalyzed Sonogashira polymerization of 2,6‐diiodo‐functionalized BODIPY monomers with 2,6‐diethynyl‐functionalized BODIPY monomers. These polymers emit in the deep‐red region with emission maxima at up to 690 nm, and exhibit significant red shifts (up to 166 and 179 nm) of both absorption and emission maxima compared with their parent BODIPY dyes due to significant extension of π‐conjugation. These polymers possess good thermal stability with decomposition temperature between 270 and 360 °C. The polymers exhibit a little larger Stokes shifts and shorter lifetime than their corresponding BODIPY dyes. The solid state thin films of polymers A , B , and C emit in near‐infrared region between 723 and 743 nm, and show significantly red shifts (up to 57 nm) in absorption and emission maxima relative to their polymer solution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5354–5366, 2009 相似文献
23.
Lalit Giri Arun Kumar Jugran Amit Bahukhandi Praveen Dhyani Indra D. Bhatt Ranbeer Singh Rawal Shyamal Kumar Nandi Uppeandra Dhar 《Applied biochemistry and biotechnology》2017,181(1):267-282
Habenaria edgeworthii Hook. f. ex Collett is an important terrestrial orchid used in different Ayurvedic formulations. In the present study, variations among morphological, phytochemical and molecular markers were assessed. A significant difference was observed among populations using morphological traits. Inter-simple sequence repeat (ISSR) data revealed lower genetic diversity at population level (He = 0.207) as compared to species level (He = 0.334). Analysis of molecular variance (AMOVA) indicates 74 % variation among populations and 26 % within population. Tuber extracts showed significantly (p < 0.05) higher total phenolics and flavonoids among the populations. Antioxidant activity determined by 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and ferric reducing antioxidant power (FRAP) assays exhibited considerable antioxidant potential. Furthermore, the associations between molecular and morphological and phytochemical attributes were studied using multiple regression analysis (MRA). Several ISSR fragments were associated with some morphological and phytochemical traits. These ISSR fragments can be useful for breeding programme of the species when no other genetic information, such as linkage maps and quantitative trait loci, is available. 相似文献
24.
25.
P. S. Suresh Sanjeev Giri Raghib Husain Ramesh Mullangi 《Biomedical chromatography : BMC》2010,24(10):1052-1058
A highly sensitive, rapid assay method has been developed and validated for the estimation of S‐citalopram (S‐CPM) in rat plasma with liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in the positive‐ion mode. The assay procedure involves a simple liquid–liquid extraction of S‐CPM and phenacetin (internal standard, IS) from rat plasma with t‐butyl methyl ether. Chromatographic separation was operated with 0.2% formic acid:acetonitrile (20:80, v/v) at a flow rate of 0.50 mL/min on a Symmetry Shield RP18 column with a total run time of 3.0 min. The MS/MS ion transitions monitored were 325.26 → 109.10 for S‐CPM and 180.10 → 110.10 for IS. Method validation and pre‐clinical sample analysis were performed as per FDA guidelines and the results met the acceptance criteria. The lower limit of quantitation achieved was 0.5 ng/mL and the linearity was observed from 0.5 to 5000 ng/mL. The intra‐ and inter‐day precisions were in the range of 1.14–5.56 and 0.25–12.3%, respectively. This novel method has been applied to a pharmacokinetic study and to estimate brain‐to‐plasma ratio of S‐CPM in rats. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
26.
Prosenjit Bose Anil Maheshwari Giri Narasimhan Michiel Smid Norbert Zeh 《Computational Geometry》2004,29(3):233-249
In a geometric bottleneck shortest path problem, we are given a set S of n points in the plane, and want to answer queries of the following type: given two points p and q of S and a real number L, compute (or approximate) a shortest path between p and q in the subgraph of the complete graph on S consisting of all edges whose lengths are less than or equal to L. We present efficient algorithms for answering several query problems of this type. Our solutions are based on Euclidean minimum spanning trees, spanners, and the Delaunay triangulation. A result of independent interest is the following. For any two points p and q of S, there is a path between p and q in the Delaunay triangulation, whose length is less than or equal to 2π/(3cos(π/6)) times the Euclidean distance |pq| between p and q, and all of whose edges have length at most |pq|. 相似文献
27.
A non-linear analysis of unbraced, rigid-jointed, and elastically restrained (against rotation) portal frames of variable geometry is presented. The loading system consists of eccentric concentrated loads and a transverse uniformly distributed load. Among the important conclusions one may list the following: (a) symmetric portal frames, loaded symmetrically, buckle through a stable bifurcation (sway-buckling) from a symmetric bent equilibrium configuration, and (b) nonsymmetric portal frames do not buckle; their behavior is similar to that of imperfect cantilever columns. 相似文献
28.
Rao K Chodisetti B Gandi S Mangamoori LN Giri A 《Applied biochemistry and biotechnology》2011,165(5-6):1366-1378
Alpinia galanga is a rhizomatous herb rich in essential oils and various other significant phytoconstituents. Rapid direct regeneration was obtained from the rhizome explants (15.66 ± 0.57 shoots) on MS media supplemented with zeatin at a concentration of 2 mg/l. The callus cultures of A. galanga were initiated from the rhizome explants on MS media supplemented with 2 mg/l each of BAP, 2,4-D, and NAA. The callus was analyzed for the presence of a vital phytoconstituent--acetoxychavicol acetate (ACA) associated with various biological properties. ACA was detected in the young friable callus as well as the stationary phase callus. Moreover, the induction of morphogenetic response in callus resulted in higher accumulation of ACA. The phytohormone withdrawal from the propagation media and the subsequent transfer of callus to BAP (2 mg/l) containing MS media has resulted in multiple shoot induction. The regenerated (indirect) plants have shown 1.6-fold higher ACA content (1.253%) when compared to the control plant (0.783%). Micropropagation of such conventionally propagated plants is very essential to meet the commercial demand as well as to ensure easy storage and transportation of disease free stocks. 相似文献
29.
30.
We have analysed the two body non-leptonic charmed-meson decays of heavyB meson based on the factorization assumption. The transition matrix elements and the corresponding decay widths are calculated
in the heavy quark and chiral symmetry limit and the Isgur-Wise function present in the expression is determined by the wave
function model of Aliet al. The results obtained are quite interesting and agree reasonably well with the experimental data. 相似文献