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991.
Kaiwu Yu Rui Zhou Yangyang Xu Yan Zhong Shufang Qian Honghai Zhang Prof. Haibin Shi Dr. Qinggang He Prof. Zhengwei Mao Prof. Haoke Zhang Prof. Yen Wei Prof. Hong Zhang Prof. Mei Tian 《化学:亚洲杂志》2021,16(23):3963-3969
A lack of efficient diagnostic tools for early and noninvasive diagnosis of breast cancer has restricted the clinical treatment effect. This problem might be addressed by the combination of aggregation-induced emission (AIE) fluorescence imaging and positron emission tomography (PET) with the dual advantages of high resolution and easy operation, and unlimited penetration and high sensitivity. Here, a mitochondria-targeted AIE luminogen (AIEgen) radiolabeled with 18F was developed through a two-step radiochemical reaction by virtue of a prosthetic group. The obtained 18/19F-Bz-CP imaging probe was examined by in vitro cell uptake and cell proliferation inhibition in two breast cancer cell lines, showing that the probe can efficiently target and locate in the mitochondria through the analysis of fluorescence imaging and PET simultaneously. Additionally, the probe can induce cancer cell apoptosis with the half maximal inhibitory concentration (IC50) of 4.8 μM for MCF-7 cells and 7.2 μM for T47D cells, indicating its potential application for breast cancer therapy. 相似文献
992.
Yen YC Kuo SW Huang CF Chen JK Chang FC 《The journal of physical chemistry. B》2008,112(35):10821-10829
In this study, we investigated the miscibility behavior and mechanism of interaction of poly(methyl mechacrylate) (PMMA), poly(vinyl pyrrolidone) PVP, and PMMA- co-PVP blends with octa(phenol)octasilsequioxane (OP-POSS). For the PMMA/OP-POSS binary blend, the value of the association constant ( K A = 29) was smaller than that in the poly(vinyl phenol) (PVPh)/PMMA ( K A = 37.4) and ethyl phenol (EPh)/PMMA ( K A = 101) blend systems, implying that the phenol groups of the OP-POSS units in the PMMA/OP-POSS blends interacted to a lesser degree with the CO groups of PMMA than they did in the other two systems. In addition, the ionic conductivity of a LiClO4/PMMA- co-PVP polymer electrolyte was increased after blending with OP-POSS. 相似文献
993.
Schantz MM Bedner M Long SE Molloy JL Murphy KE Porter BJ Putzbach K Rimmer CA Sander LC Sharpless KE Thomas JB Wise SA Wood LJ Yen JH Yarita T NguyenPho A Sorenson WR Betz JM 《Analytical and bioanalytical chemistry》2008,392(3):427-438
As part of a collaboration with the National Institutes of Health’s Office of Dietary Supplements and the Food and Drug Administration’s
Center for Drug Evaluation and Research, the National Institute of Standards and Technology has developed two standard reference
materials (SRMs) representing different forms of saw palmetto (Serenoa repens), SRM 3250 Serenoa repens fruit and SRM 3251 Serenoa repens extract. Both of these SRMs have been characterized for their fatty acid and phytosterol content. The fatty acid concentration
values are based on results from gas chromatography with flame ionization detection (GC-FID) and mass spectrometry (GC/MS)
analysis while the sterol concentration values are based on results from GC-FID and liquid chromatography with mass spectrometry
analysis. In addition, SRM 3250 has been characterized for lead content, and SRM 3251 has been characterized for the content
of β-carotene and tocopherols. SRM 3250 (fruit) has certified concentration values for three phytosterols, 14 fatty acids
as triglycerides, and lead along with reference concentration values for four fatty acids as triglycerides and 16 free fatty
acids. SRM 3251 (extract) has certified concentration values for three phytosterols, 17 fatty acids as triglycerides, β-carotene,
and γ-tocopherol along with reference concentration values for three fatty acids as triglycerides, 17 fatty acids as free
fatty acids, β-carotene isomers, and δ-tocopherol and information values for two phytosterols. These SRMs will complement
other reference materials currently available with concentrations for similar analytes and are part of a series of SRMs being
developed for dietary supplements.
Contribution of the US Government; not subject to copyright 相似文献
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997.
Cha‐Wen Chang Hung‐Ju Yen Kuan‐Yeh Huang Jui‐Ming Yeh Guey‐Sheng Liou 《Journal of polymer science. Part A, Polymer chemistry》2008,46(24):7937-7949
Four series of polyimides I – VI with pendent triphenylamine (TPA) units having inherent viscosities of 0.44–0.88 dL/g were prepared from four diamines with two commercially available tetracarboxylic dianhydrides via a conventional two‐step procedure that included a ring‐opening polyaddition to give polyamic acids, followed by chemical cyclodehydration. These polymers were amorphous and could afford flexible films. All the polyimides had useful levels of thermal stability associated with high softening temperatures (279–300 °C), 10% weight‐loss temperatures in excess of 505 °C, and char yields at 800 °C in nitrogen higher than 58%. The hole‐transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the polyimide films cast onto an indium‐tin oxide (ITO)‐coated glass substrate exhibited a or two reversible oxidation couples at 0.65–0.78 and 1.00–1.08 V versus Ag/AgCl in acetonitrile solution. The polymer films revealed electrochromic characteristics with a color change from neutral pale yellowish to blue doped form at applied potentials ranging from 0.00 to 1.20 V. The CO2 permeability coefficients (P) and permeability selectivity (P/P) for these polyimide membranes were in the range of 4.73–16.82 barrer and 9.49–51.13, respectively. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7937–7949, 2008 相似文献
998.
Simple HPLC-UV determination of nucleosides and its application to the authentication of Cordyceps and its allies 总被引:1,自引:0,他引:1
A simple HPLC-UV method combined with a simple extraction procedure of nucleosides (adenosine, cordycepin, 2'-deoxyadenosine, guanosine and uridine) was developed and applied to the authentication of Cordyceps and its allies. The separation was performed on a C(18) column by isocratic elution with acetonitrile-water, and UV detection at 260 nm. The amounts of adenosine, cordycepin, 2'-deoxyadenosine, guanosine and uridine in Cordyceps were 0.28-14.15, 0.006-6.36, 0.01-0.14, 0.68-14.79 and 0.19-20.29 mg/g, respectively. Among the nucleosides studied, cordycepin was characteristically included in Cordyceps militaris (L.) Link. (CM), which is one of key Cordyceps allies, and might be a good marker for authenticating CM. The ratio of nucleosides to adenosine contents in Cordyceps seemed to be a useful marker for authentication and quality control of Cordyceps. 相似文献
999.
Koppisch AT Hotta K Fox DT Ruggiero CE Kim CY Sanchez T Iyer S Browder CC Unkefer PJ Unkefer CJ 《The Journal of organic chemistry》2008,73(15):5759-5765
The biosynthesis of the 3,4-dihydroxybenzoate moieties of the siderophore petrobactin, produced by B. anthracis str. Sterne, was probed by isotopic feeding experiments in iron-deficient media with a mixture of unlabeled and D-[(13)C6]glucose at a ratio of 5:1 (w/w). After isolation of the labeled siderophore, analysis of the isotopomers was conducted via one-dimensional (1)H and (13)C NMR spectroscopy, as well as (13)C-(13)C DQFCOSY spectroscopy. Isotopic enrichment and (13)C-(13)C coupling constants in the aromatic ring of the isolated siderophore suggested the predominant route for the construction of the carbon backbone of 3,4-DHB (1) involved phosphoenol pyruvate and erythrose-4-phosphate as ultimate precursors. This observation is consistent with that expected if the shikimate pathway is involved in the biosynthesis of these moieties. Enrichment attributable to phosphoenol pyruvate precursors was observed at C1 and C6 of the aromatic ring, as well as into the carboxylate group, while scrambling of the label into C2 was not. This pattern suggests 1 was biosynthesized from early intermediates of the shikimate pathway and not through later shikimate intermediates or aromatic amino acid precursors. 相似文献
1000.
Dr. Corinne A. Lutomski Dr. Tarick J. El-Baba Dr. Joshua D. Hinkle Dr. Idlir Liko Jack L. Bennett Dr. Neha V. Kalmankar Dr. Andrew Dolan Carla Kirschbaum Kim Greis Prof. Dr. Leonhard H. Urner Dr. Parth Kapoor Prof. Hsin-Yung Yen Prof. Kevin Pagel Dr. Christopher Mullen Dr. John E. P. Syka Prof. Carol V. Robinson 《Angewandte Chemie (International ed. in English)》2023,62(36):e202305694
Membrane proteins are challenging to analyze by native mass spectrometry (MS) as their hydrophobic nature typically requires stabilization in detergent micelles that are removed prior to analysis via collisional activation. There is however a practical limit to the amount of energy which can be applied, which often precludes subsequent characterization by top-down MS. To overcome this barrier, we have applied a modified Orbitrap Eclipse Tribrid mass spectrometer coupled to an infrared laser within a high-pressure linear ion trap. We show how tuning the intensity and time of incident photons enables liberation of membrane proteins from detergent micelles. Specifically, we relate the ease of micelle removal to the infrared absorption of detergents in both condensed and gas phases. Top-down MS via infrared multiphoton dissociation (IRMPD), results in good sequence coverage enabling unambiguous identification of membrane proteins and their complexes. By contrasting and comparing the fragmentation patterns of the ammonia channel with two class A GPCRs, we identify successive cleavage of adjacent amino acids within transmembrane domains. Using gas-phase molecular dynamics simulations, we show that areas prone to fragmentation maintain aspects of protein structure at increasing temperatures. Altogether, we propose a rationale to explain why and where in the protein fragment ions are generated. 相似文献