全文获取类型
收费全文 | 176篇 |
免费 | 8篇 |
专业分类
化学 | 127篇 |
晶体学 | 2篇 |
力学 | 2篇 |
数学 | 24篇 |
物理学 | 29篇 |
出版年
2024年 | 3篇 |
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 4篇 |
2020年 | 6篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 9篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 15篇 |
2012年 | 8篇 |
2011年 | 10篇 |
2010年 | 5篇 |
2009年 | 7篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2004年 | 6篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 4篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有184条查询结果,搜索用时 31 毫秒
91.
Brittany P. Rickard Marta Overchuk Girgis Obaid Mustafa Kemal Ruhi Utkan Demirci Suzanne E. Fenton Janine H. Santos David Kessel Imran Rizvi 《Photochemistry and photobiology》2023,99(2):448-468
Ovarian cancer is the most lethal gynecologic malignancy with a stubborn mortality rate of ~65%. The persistent failure of multiline chemotherapy, and significant tumor heterogeneity, has made it challenging to improve outcomes. A target of increasing interest is the mitochondrion because of its essential role in critical cellular functions, and the significance of metabolic adaptation in chemoresistance. This review describes mitochondrial processes, including metabolic reprogramming, mitochondrial transfer and mitochondrial dynamics in ovarian cancer progression and chemoresistance. The effect of malignant ascites, or excess peritoneal fluid, on mitochondrial function is discussed. The role of photodynamic therapy (PDT) in overcoming mitochondria-mediated resistance is presented. PDT, a photochemistry-based modality, involves the light-based activation of a photosensitizer leading to the production of short-lived reactive molecular species and spatiotemporally confined photodamage to nearby organelles and biological targets. The consequential effects range from subcytotoxic priming of target cells for increased sensitivity to subsequent treatments, such as chemotherapy, to direct cell killing. This review discusses how PDT-based approaches can address key limitations of current treatments. Specifically, an overview of the mechanisms by which PDT alters mitochondrial function, and a summary of preclinical advancements and clinical PDT experience in ovarian cancer are provided. 相似文献
92.
The ultraviolet photochemistry of phenylacetylene and the enthalpy of formation of 1,3,5-hexatriyne. 总被引:1,自引:0,他引:1
The ultraviolet photochemistry of phenylacetylene was studied in a molecular beam at 193 nm. The only primary photofragments observed were HCCH (acetylene) and C(6)H(4). Some of the C(6)H(4) molecules were found to decompose to 1,3,5-hexatriyne and molecular hydrogen. An enthalpy of formation of DeltaH(f) < or = 160 +/- 4 kcal mol(-1) was determined for 1,3,5-hexatriyne from the energetic threshold for this process. This experimentally determined value agrees well with our ab initio calculations performed at the G2 level of theory. Angular distribution measurements for the HCCH + C(6)H(4) channel yielded an isotropic distribution and were attributed to a long-lived intermediate and ground-state dissociation. An exhaustive search yielded no evidence for the phenyl + ethynyl or the atomic hydrogen elimination channels even though these were observed in the pyrolytic studies of phenylacetylene [Hofmann, J.; Zimmermann, G.; Guthier, K.; Hebgen, P.; Homann, K. H. Liebigs Ann. 1995, 631, 1995. Guthier, K.; Hebgen, P.; Hofmann, K. H.; Zimmermann, G. Liebigs Ann. 1995, 637, 1995]. 相似文献
93.
Abdul Shakoor Tasneem Zahra Rizvi Hafiz Umer Farooq Najmul Hassan Abdul Majid Muhammad Saeed Muhammad Farooq 《Polymer Science Series A》2013,55(4):279-284
Polypyrrole is synthesized and doped with Dodecylbenzenesulphonic acid. The doped Polypyrrole with Dodecylbenzenesulphonic acid is intercalated into the layers of Montmorillonite clay successfully by in situ polymerization. The structural properties of synthesized doped Polypyrrole and intercalated doped Polypyrrole were studied by XRD analysis. The crystallinity of intercalated doped Polypyrrole into the layers of Montmorillonite clay is confirmed by means of X-rays diffraction studies, which is more than the doped Polypyrrole. Enhanced d-spacing of Montmorillonite confirmed that doped Polypyrrole is interclated into the layers of Montmorillonite clay at nanoscale. The scanning electron micrographs also confirm the formation of dual phase of platelet as well as of flaky structure of intercalated doped Polypyrrole. Temperature dependant conductivity showed three dimensional variable ranges hopping model. Activation energy, density of states and hopping length are calculated and found to be influenced by intercalating Doped Polypyrole into the layers of Montmorillonite clay. 相似文献
94.
Determination of elemental fingerprint profile of 40 commercial beer samples was performed using inductively coupled plasma–mass
spectrometry combined with principal component analysis and receiver operating characteristic (ROC) analysis. Fourteen trace
elements, 51V, 52Cr, 59Co, 60Ni, 75As, 82Se, 95Mo, 111Cd, 115In, 121Sb, 133Cs, 208Pb, 209Bi, and 238U, were monitored. All 40 beer samples are distinguishable by using the proposed method. ROC analysis showed that individual
beer samples can be correctly identified via the magnitude of its correlation coefficient with respect to the other beers
with low false positive rate. The obtained results suggested that the elemental fingerprint technique is feasible for sample
differentiation and comparison. 相似文献
95.
Md. Irshad Alam Aquil ur‐Rahim Siddiqui Nazia Khanam Shaikh Jalil Kamaruddin 《Journal of separation science》2020,43(18):3597-3606
An innovative high‐performance liquid chromatography assay method was developed and validated for quantification of dextromethorphan hydrobromide and desloratadine simultaneously in monophasic liquid formulation by preparing syrup containing 30 mg/5 mL of dextromethorphan hydrobromide and 1.2 mg/mL of desloratadine. The chromatographic severance was executed by gradient solution A and B. The composition of buffer solution A contained 0.05 M monobasic potassium, then 1 mL triethylamine was added to it and the pH was adjusted to 2.3 with orthophosphoric acid. Methanol was used as solution B. The gradient elution was executed with Kromasil C8 (250 mm × 4.6 mm) column having 1.5 mL/min flow rate and 20 µL injection volume with UV‐estimation at 254 nm for dextromethorphan hydrobromide and DES. The present research was planned according to Box‐Behnken design by utilizing design expert software, using four factors such as column temperature (A), flow rate (B), mobile phase–organic phase (C), and pH (D); correspondingly the selected response variables were resolution between A and B, that is, desloratadine and methyl paraben (Y1), tailing of dextromethorphan hydrobromide (Y2), and tailing of desloratadine (Y3). The parameters such as system suitability, linearity, accuracy, precision, robustness, limit of detection, limit of quantitation, and ruggedness were analyzed to validate the developed method in accordance with current regulatory guidelines. 相似文献
96.
Resveratrol, the red-wine polyphenol, is intensively studied polyphenols for its pleiotropic biological effects. A plethora of health beneficial effects of this stilbene has been reported including cardio-protective, neuro-protective, anti-cancer, anti-diabetic and interesting anti-aging. Though it has been proposed that these effects of resveratrol arise from its capacity to interact with multiple molecular targets involved in diverse intracellular pathways including activation of sirtuins, the antioxidant property of this compound is the most described one to attribute its diverse health beneficial effects. In the present review we have explained the biological activities of resveratrol with the latest laboratory evidences towards its antioxidant effects. 相似文献
97.
Yaroslavov AA Sybachin AV Kesselman E Schmidt J Talmon Y Rizvi SA Menger FM 《Journal of the American Chemical Society》2011,133(9):2881-2883
Cryo-TEM and NaCl-leakage experiments demonstrated that the cationic polymer polylysine induces fusion of anionic liposomes but that the cationic polymer poly(N-ethyl-4-vinylpyridinium bromide) (PEVP) does not, although both polymers bind strongly to the liposomes. The difference was traced to the thickness of the coatings at constant charge coverage. Polylysine is believed to form planar β-sheets that are sufficiently thin to allow membrane fusion. In contrast, looping and disorganization among adsorbed PEVP molecules physically prevent fusion. A similar effect is likely to be applicable to important polycation-induced fusion of cell membranes. 相似文献
98.
We introduce the notion of 𝒦-nonsingularity of a module and show that the class of 𝒦-nonsingular modules properly contains the classes of nonsingular modules and of polyform modules. A necessary and sufficient condition is provided to ensure that this property is preserved under direct sums. Connections of 𝒦-nonsingular modules to their endomorphism rings are investigated. Rings for which all modules are 𝒦-nonsingular are precisely determined. Applications include a type theory decomposition for 𝒦-nonsingular extending modules and internal characterizations for 𝒦-nonsingular continuous modules which are of type I, type II, and type III, respectively. 相似文献
99.
In this paper, we consider a generalized mixed equilibrium problem in real Hilbert space. Using the auxiliary principle, we define a class of resolvent mappings. Further, using fixed point and resolvent methods, we give some iterative algorithms for solving generalized mixed equilibrium problem. Furthermore, we prove that the sequences generated by iterative algorithms converge weakly to the solution of generalized mixed equilibrium problem. These results require monotonicity (θ-pseudo monotonicity) and continuity (Lipschitz continuity) for mappings. 相似文献
100.
F. K. Amanuel B. Zelalem A. K. Chaubey Avinash Agarwal I. A. Rizvi Anjana Maheshwari Tauseef Ahmed 《The European Physical Journal A - Hadrons and Nuclei》2011,47(12):156
In this paper, we present the results of our investigation of reaction dynamics leading to incomplete fusion of heavy ions
at moderate excitation energies, especially the influence of incomplete fusion on complete fusion of 12C -induced reactions at specific energies ≈ 4–7.2M eV/nucleon. Excitation functions of various reaction products populated
via complete and/or incomplete fusions of a 12C projectile with 93Nb, 59Co and 52Cr targets were measured at several specific energies ≈ 4–7.2 MeV/nucleon, using a recoil catcher technique, followed by off-line
γ-ray spectrometry. The measured excitation functions were compared with theoretical values obtained using the PACE4 statistical
model code. For representative non-α-emitting channels in the 12C + 93Nb system, the experimentally measured excitation functions were, in general, found to be in good agreement with the theoretical
predictions. However, for α-emitting channels in the 12C + 93Nb, 12C + 59Co, and 12C + 52Cr systems, the measured excitation functions were higher than the predictions of the theoretical model code, which may be
credited to incomplete fusion reactions at these energies. An attempt was made to estimate the incomplete fusion fraction
for the present systems, which revealed that the fraction was sensitive to the projectile energy and mass asymmetry of the
entrance channel. 相似文献