全文获取类型
收费全文 | 642篇 |
免费 | 29篇 |
国内免费 | 3篇 |
专业分类
化学 | 497篇 |
晶体学 | 2篇 |
力学 | 11篇 |
数学 | 48篇 |
物理学 | 116篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 16篇 |
2020年 | 13篇 |
2019年 | 17篇 |
2018年 | 13篇 |
2017年 | 11篇 |
2016年 | 18篇 |
2015年 | 17篇 |
2014年 | 18篇 |
2013年 | 30篇 |
2012年 | 44篇 |
2011年 | 58篇 |
2010年 | 26篇 |
2009年 | 14篇 |
2008年 | 46篇 |
2007年 | 39篇 |
2006年 | 44篇 |
2005年 | 45篇 |
2004年 | 43篇 |
2003年 | 49篇 |
2002年 | 31篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有674条查询结果,搜索用时 0 毫秒
61.
Runyan Ni Naoto Mitsuda Takeru Kashiwagi Kazunobu Igawa Katsuhiko Tomooka 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(4):1206-1210
A variety of medium‐sized cycloalkynes were efficiently synthesized by the double Nicholas reaction of cobalt complex and bis(hetero)substituted acyclic compound. The alkyne moiety within the ring has a unique bent structure and high reactivity toward cycloaddition reactions. Furthermore, preparation of multifunctionalized alkynes was achieved by embedding the cycloalkyne within a peptide chain. 相似文献
62.
Kuwamura N Kitano K Hirotsu M Nishioka T Teki Y Santo R Ichimura A Hashimoto H Wright LJ Kinoshita I 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(38):10708-10715
Interchange between the nickel +2 and +3 oxidation states precisely controls the reversible rearrangement of the tris(2-pyridylthio)methanide (tptm) ligand in the organometallic nickel(II) complex [{Ni(μ-Br)-(tptm)}(2)] (2). Oxidation of 2 first gives the corresponding Ni(III) complex [{Ni(μ-Br)(tptm)}(2)][PF(6)](2) (4). However, in solution the tptm ligand in 4 slowly undergoes a rearrangement, in which the N and S atoms of one of the pyridylthiolate arms exchange Ni and C bonding partners, thereby resulting in an "N,S-confused" isomer of tptm in the product, [NiBr(bpttpm)]PF(6) (5; bpttpm= bis(2-pyridylthio)(2-thiopyridinium)-methyl). Reduction of 5 reverses this ligand rearrangement and 2 is reformed quantitatively. The individual steps involved in these unusual ligand rearrangements were investigated by a number of methods, including voltammetric analysis, and a mechanism for this process is proposed. X-ray crystal structure determinations of the key compounds 2, 4 and 5 have been obtained. 相似文献
63.
Fukumoto Y Hagihara M Kinashi F Chatani N 《Journal of the American Chemical Society》2011,133(26):10014-10017
The reaction of terminal alkynes with hydrosilanes and tert-alkyl isocyanides in the presence of Rh(4)(CO)(12) gives (Z)-β-silyl-α,β-unsaturated imines in good yields. On the other hand, the use of aryl isocyanides in place of tert-alkyl isocyanides leads to the formation of E isomers. 相似文献
64.
A simple and sensitive high-performance liquid chromatography (HPLC) method was developed to quantitate imatinib in human plasma. Imatinib and the internal standard dasatinib were separated using a mobile phase of 0.5% KH(2)PO(4) (pH3.5)-acetonitrile-methanol (55:25:20, v/v/v) on a CAPCELL PAK C18 MG II column (250 mm × 4.6 mm) at a flow rate of 0.5 mL/min and measurement at UV 265 nm. Analysis required 100 μL of plasma and involved a solid phase extraction with an Oasis HLB cartridge, which gave recoveries of imatinib from 73% to 76%. The lower limit of quantification for imatinib was 10 ng/mL. The linear range of this assay was between 10 and 5000 ng/mL (regression line r(2) > 0.9992). Inter- and intra-day coefficients of variation were less than 11.9% and accuracies were within 8.3% over the linear range. The plasma concentrations of imatinib obtained by our present method were almost the same as those assayed by an LC-MS-MS method at the Toray Research Center, Inc. This method can be applied effectively to measure imatinib concentrations in clinical samples. 相似文献
65.
Tanaka H Zaima N Yamamoto N Suzuki M Mano Y Konno H Unno N Setou M 《Analytical and bioanalytical chemistry》2011,400(7):1873-1880
Arteriovenous fistulae (AVF) using vein grafts are frequently used for vascular access in hemodialysis. When superficial veins
are used as autogenous access grafts for hemodialysis, atherosclerotic-like tissue degeneration often causes stenosis and
obstruction. Although the differences between the pathology of degeneration in AVF and atherosclerosis (i.e., peripheral artery
occlusive disease (PAD)) are known, their underlying molecular mechanisms are not. We determined the characteristic abnormal
lipid metabolism of AVF. Oil red O staining clearly showed the accumulation of lipid molecules in AVF and PAD tissues. We
found that the staining pattern was different between AVF and PAD tissues. The media and adventitia of AVF and the intima
and media of PAD were intensely stained. Quantitative lipid analysis revealed that the amount of PL was significantly increased
in AVF and PAD. Next, we performed matrix-assisted laser desorption/ionization imaging mass spectroscopy and determined the
characteristic distribution of lysophosphatidylcholine (LPC) and phosphatidylcholine (PC) in AVF. The distribution patterns
of LPC (1-acyl 16:0) and PC (diacyl 16:0/20:4) were consistent with the Oil red O staining images, suggesting that metabolisms
related to LPC (1-acyl 16:0) and PC (diacyl 16:0/20:4) are altered in AVF. 相似文献
66.
Nanostructured noble metals exhibit an intense optical near field due to surface plasmon resonance, therefore promising widespread
applications and being of interest to a broad spectrum of scientists, ranging from physicists, chemists, and materials scientists
to biologists. A wealth of research is available discussing the synthesis, characterization, and application of noble metal
nanoparticles in optical sensing. However, with respect to the sensitivity of the frequency and width of these surface plasmon
resonance modes to the particle’s shape, size, and environment, in nearly every case, success strongly depends on the availability
of highly stable, adhesive, and sensitive nanoparticles. This undoubtedly presents a challenging task to nanofabrication.
The past decade has witnessed fascinating advances in this field, in particular, the construction of oxide-based hybrid plasmonic
interfaces to overcome the problem addressed above by (1) coating the metallic nanostructures with thin overlayers to form
sandwiched structures or (2) embedding metallic nanostructures in a dielectric matrix to obtain metal/dielectric matrix nanocomposite
films. In this critical review, we focus on recent work related to this field, beginning with a presentation of hybrid films
with enhanced structural and optical stability, readily and selectively designed using chemical and physical techniques. We
then illustrate their interesting optical properties and demonstrate exciting evidence for the postulated application in surface
plasmon sensing fields. Finally, we survey the work remaining to be done for that potential to be realized. 相似文献
67.
We performed the first investigations of coherent acoustic phonons in Au-Ag core-shell nanorods, which were compared with the results of parental Au nanorods. Both breathing and extensional modes were observed in Au-Ag core-shell nanorods with ~11 nm Ag shell while only extensional modes were detected in other core-shell nanorods with 4-7 nm Ag shell. Young's modulus estimated from the oscillation period of extensional modes was found to be larger for Au-Ag core-shell nanorods with ~4 nm Ag shell, as compared with that of Au nanorods. The value of Young's modulus decreases with the increase of the Ag shell thickness and finally becomes smaller than that of Au nanorods. This phenomenon is interpreted in terms of the surface effects and the existence of grain boundaries in the lattice structure of Ag shell. 相似文献
68.
Saeki A Yamamoto N Yoshida Y Kozawa T 《The journal of physical chemistry. A》2011,115(36):10166-10173
Dynamics of radical cations and electrons in an admixture of a linear saturated hydrocarbon (n-dodecane) and halocarbon (carbon tetrachloride, CCl(4)) were investigated by picosecond electron beam pulse radiolysis. The decay of thermalized electrons (e(th)(-)) observed in infrared transient photoabsorption were simply accelerated by the addition of CCl(4), giving a high rate constant of 2.3 × 10(11) mol(-1) dm(3) s(-1). The decrease of the initial yield of e(th)(-) was quantified by C(37) (50 mmol), which is linked to the reaction of epithermal electrons (e(-)) with CCl(4). In contrast, the n-dodecane radical cation (RH(2)(?+)) monitored in the near-infrared indicated a convex-type dependence of the decay rate on CCl(4) concentration, although the initial yield of RH(2)(?+) remained almost constant up to a much higher CCl(4) concentration. The decay of RH(2)(?+) was analyzed by Monte Carlo simulations of geminate ion recombination with e(th)(-), chlorine anion (Cl(-)) formed via dissociative electron attachment, and CCl(4) radical anion. The results showed a good agreement with the experiments by considering two assumptions: (1) CCl(4) radical anion formed via e(th)(-) attachment and (2) narrowing of the initial distribution of Cl(-). The decrease in the initial yield of RH(2)(?+) at high CCl(4) concentration was well explained by immediate decomposition of CCl(4)(?+) to CCl(3)(+) and hole transfer from CCl(4)(?+) to adjacent RH(2) without diffusive motion of the reactants. Time-dependent density functional theory supported the spectroscopic assignment of intermediate species in the n-dodecane/CCl(4) system. The present results would be of help in understanding the electron capture reaction in multicomponent systems such as a chemically amplified resist in lithography. 相似文献
69.
Preparation of carbon quantum dots with tunable photoluminescence by rapid laser passivation in ordinary organic solvents 总被引:2,自引:0,他引:2
Li X Wang H Shimizu Y Pyatenko A Kawaguchi K Koshizaki N 《Chemical communications (Cambridge, England)》2011,47(3):932-934
A simple approach to prepare carbon quantum dots is presented in this communication by laser rapid passivation of nano carbon particles in ordinary organic solvent. The as-prepared carbon dots exhibited visible, tunable and stable photoluminescence (PL). XPS analysis showed that the increased oxygen concentration might be concerned with the origin of PL. 相似文献
70.
TiO(2) nanocrystals are assembled together by interfacial Ti-Ti electronic bonding. Such nanocrystal assemblies have a narrower band gap, greatly enhanced visible light absorption, and solar photocatalysis compared with individual nanocrystals. 相似文献