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571.
Ken-ichi Shimizu Maki Sakamoto Manabu Hamada Toshinori Higashi Takeshi Sugai Mitsuru Shoji 《Tetrahedron: Asymmetry》2010,21(16):2043-2049
The substrate specificity of an engineered Bacillus subtilis epoxide hydrolase, which so far had shown high activity and enantioselectivity with 1-benzyloxymethyl-1-methyloxirane, has been studied by altering the methyl substituent into hydrogen, oxygen-containing functionalities, and unsaturated homologs. High enantioselectivity (E = 44) was observed with 1-benzyloxymethyl-1-vinyloxirane with a proper catalytic activity. The elaboration of the reaction conditions and work-up procedures enabled a preparative-scale kinetic resolution, to give (R)-2-benzyloxymethyl-3-butene-1,2-diol and its antipodal (R)-epoxide in high ees. 相似文献
572.
Tom Burr Stephen Croft Michael S. Hamada Stephen Vardeman Brian Weaver 《Accreditation and quality assurance》2012,17(5):485-490
A previous related paper considered rounding error effects in the presence of underlying measurement error and presented a Bayesian approach to estimate instrument input random error standard deviation. This addendum to the previous paper emphasizes that the effects of random error depend on the true (and usually unknown) value of the measurand, in terms of both the variance and the item-specific bias. However, it is shown that if we assume that the true values are uniformly distributed, then instrument variance and item-specific bias can be combined into an ??effective random error variance?? and a strategy to estimate the effective random error variance is provided. 相似文献
573.
Shinya Harusawa Shuji Nakamura Sayoko Yagi Takushi Kurihara Yasumasa Hamada Takayuki Shioiri 《合成通讯》2013,43(14):1365-1371
A simple and convenient procedure for the syntheses of some nonsteroidal anti-inflammatory agents, ibuprofen, rac-naproxen, clidanac and loxoprofen, is described. 相似文献
574.
575.
Daiki Yamane Satsuki Onitsuka Suyong Re Hikaru Isogai Rui Hamada Tadanari Hiramoto Eiji Kawanishi Kenji Mizuguchi Naoya Shindo Akio Ojida 《Chemical science》2022,13(10):3027
The coronavirus disease 2019 (COVID-19) pandemic has necessitated the development of antiviral agents against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The main protease (Mpro) is a promising target for COVID-19 treatment. Here, we report an irreversible SARS-CoV-2 Mpro inhibitor possessing chlorofluoroacetamide (CFA) as a warhead for the covalent modification of Mpro. Ugi multicomponent reaction using chlorofluoroacetic acid enabled the rapid synthesis of dipeptidic CFA derivatives that identified 18 as a potent inhibitor of SARS-CoV-2 Mpro. Among the four stereoisomers, (R,R)-18 exhibited a markedly higher inhibitory activity against Mpro than the other isomers. Reaction kinetics and computational docking studies suggest that the R configuration of the CFA warhead is crucial for the rapid covalent inhibition of Mpro. Our findings highlight the prominent influence of the CFA chirality on the covalent modification of proteinous cysteines and provide the basis for improving the potency and selectivity of CFA-based covalent inhibitors.Chlorofluoroacetamide (CFA) was used as the warhead for covalent targeting of SARS-CoV-2 Mpro. The chirality at CFA showed marked influence on inhibitory activity, suggesting stereospecific activation of CFA for cysteine modification in the protein. 相似文献
576.
Manal Y. Sameeh Manal M. Khowdiary Hisham S. Nassar Mahmoud M. Abdelall Hamada H. Amer Abdelaaty Hamed Ahmed A. Elhenawy 《Molecules (Basel, Switzerland)》2022,27(3)
This work aimed to synthesize a new antihyperglycemic thiazolidinedione based on the spectral data. The DFT\B3LYP\6-311G** level of theory was used to investigate the frontier molecular orbitals (FMOs), chemical reactivity and map the molecular electrostatic potentials (MEPs) to explain how the synthesized compounds interacted with the receptor. The molecular docking simulations into the active sites of PPAR-γ and α-amylase were performed. The in vitro potency of these compounds via α-amylase and radical scavenging were evaluated. The data revealed that compounds (4–6) have higher potency than the reference drugs. The anti-diabetic and anti-hyperlipidemic activities for thiazolidine-2,4-dione have been investigated in vivo using the alloxan-induced diabetic rat model along with the 30 days of treatment protocol. The investigated compounds didn’t show obvious reduction of blood glucose during pre-treatments compared to diabetic control, while after 30 days of treatments, the blood glucose level was lower than that of the diabetic control. Compounds (4–7) were able to regulate hyperlipidemia levels (cholesterol, triglyceride, high-density lipoproteins and low- and very-low-density lipoproteins) to nearly normal value at the 30th day. 相似文献
577.
578.
Tahira Sultana Madiha Ahmed Nosheen Akhtar Mohammad K. Okla Abdulrahman Al-Hashimi Wahidah H. Al-Qahtani Hamada Abdelgawad Ihsan-ul-Haq 《Molecules (Basel, Switzerland)》2022,27(2)
The present study was designed to evaluate polarity-dependent extraction efficiency and pharmacological profiling of Polygonum glabrum Willd. Crude extracts of leaves, roots, stems, and seeds, prepared from solvents of varying polarities, were subjected to phytochemical, antioxidant, antibacterial, antifungal, antidiabetic, and cytotoxicity assays. Maximum extraction yield (20.0% w/w) was observed in the case of an acetone:methanol (AC:M) root extract. Distilled water:methanol (W:M) leaves extract showed maximum phenolic contents. Maximum flavonoid content and free radical scavenging potential were found in methanolic (M) seed extract. HPLC-DAD quantification displayed the manifestation of substantial quantities of quercetin, rutin, gallic acid, quercetin, catechin, and kaempferol in various extracts. The highest ascorbic acid equivalent total antioxidant capacity and reducing power potential was found in distilled water roots and W:M leaf extracts, respectively. Chloroform (C) seeds extract produced a maximum zone of inhibition against Salmonella typhimurium. Promising protein kinase inhibition and antifungal activity against Mucor sp. were demonstrated by C leaf extract. AC:M leaves extract exhibited significant cytotoxic capability against brine shrimp larvae and α-amylase inhibition. Present results suggest that the nature of pharmacological responses depends upon the polarity of extraction solvents and parts of the plant used. P. glabrum can be considered as a potential candidate for the isolation of bioactive compounds with profound therapeutic importance. 相似文献
579.
Numerical analysis and experimental results of output performance for Nd-doped double-clad fiber lasers 总被引:10,自引:0,他引:10
Nam Seong Kim Toshihiro Hamada Mahendra Prabhu Cheng Li Jie Song Ken-ichi Ueda Anping Liu Hong Jin Kong 《Optics Communications》2000,180(4-6):329-337
Numerical analysis is investigated for the high-power double-clad fiber lasers and experimental results using different microscope objectives for focusing into a Nd-doped rectangular double-clad fiber also performed. The numerical analysis includes dependence of output power on output mirror reflectivity, absorbed pump power, loss, and fiber length and pump power distribution for the cases of one-end and two-end pumps with 20 dB/km loss. Calculated conversion efficiencies are 76.36%, 69.73%, and 63.84% for lossless, two-end pump, and one-end pump fiber lasers, respectively. Slope efficiencies from absorbed pump power/output powers measured using microscope objectives are 16.8%/182 mW, 53.8%/351 mW, 24.9%/1240 mW, and 13.9%/649 mW for magnifications of 5×, 10×, 20×, and 40×, respectively. 相似文献
580.
Shinya Harusawa Ryuji Yoneda Takushi Kurihara Yasumasa Hamada Takayuki Shioiri 《Tetrahedron letters》1984,25(4):427-428
Reaction of aromatic ketones with diethyl phosphorocyanidate in the presence of lithium cyanide gave cyanophosphates, which were converted into α,β-unsaturated nitriles by treatment with boron trifluoride etherate in high yields. 相似文献