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971.
A catalytic, green and practical method for Friedel-Crafts hydroxyalkylation of mucohalic acid has been accomplished. Reaction of mucohalic acids with various electron-rich aromatic compounds in the presence of catalytic (1 mol % to 10 mol %) In(OTf)3 or Brönsted acid, such as H2SO4 in acetic acid provides γ-aryl γ-butenolides in moderate to excellent yield. 相似文献
972.
Emma van Groesen Dr. Christopher T. Lohans Dr. Jürgen Brem Kristina M. J. Aertker Prof. Dr. Timothy D. W. Claridge Prof. Dr. Christopher J. Schofield 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(51):11837-11841
Bacterial production of β-lactamases with carbapenemase activity is a global health threat. The active sites of class D carbapenemases such as OXA-48, which is of major clinical importance, uniquely contain a carbamylated lysine residue which is essential for catalysis. Although there is significant interest in characterizing this post-translational modification, and it is a promising inhibition target, protein carbamylation is challenging to monitor in solution. We report the use of 19F NMR spectroscopy to monitor the carbamylation state of 19F-labelled OXA-48. This method was used to investigate the interactions of OXA-48 with clinically used serine β-lactamase inhibitors, including avibactam and vaborbactam. Crystallographic studies on 19F-labelled OXA-48 provide a structural rationale for the sensitivity of the 19F label to active site interactions. The overall results demonstrate the use of 19F NMR to monitor reversible covalent post-translational modifications. 相似文献
973.
Synthesis of the seco-Limonoid BCD Ring System Identifies a Hsp90 Chaperon Machinery (p23) Inhibitor
Dr. David M. Pinkerton Dr. Sharon Chow Nada H. Eisa Kashish Kainth Timothy J. Vanden Berg Dr. Jed M. Burns Assoc. Prof. Luke W. Guddat Dr. G. Paul Savage Prof. Ahmed Chadli Prof. Craig M. Williams 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(6):1451-1455
D-Ring-seco-limonoids (tetranortriterpenoids), such as gedunin and xylogranin B display anti-cancer activity, acting via inhibition of Hsp90 and/or associated chaperon machinery (e.g., p23). Despite this, these natural products have received relatively little attention, both in terms of an enabling synthetic approach (which would allow access to derivatives), and as a consequence their structure–activity relationship (SAR). Disclosed herein is a generally applicable synthetic route to the BCD ring system of the seco-D-ring double bond containing limonoids. Furthermore, cell based assays revealed the first skeletal fragment that exhibited inhibition of the p23 enzyme at a level which was equipotent to that of gedunin, despite being much less structurally complex. 相似文献
974.
Murugesan Velayutham Martin Poncelet Timothy D. Eubank Benoit Driesschaert Valery V. Khramtsov 《Molecules (Basel, Switzerland)》2021,26(9)
Alterations in viscosity of biological fluids and tissues play an important role in health and diseases. It has been demonstrated that the electron paramagnetic resonance (EPR) spectrum of a 13C-labeled trityl spin probe (13C-dFT) is highly sensitive to the local viscosity of its microenvironment. In the present study, we demonstrate that X-band (9.5 GHz) EPR viscometry using 13C-dFT provides a simple tool to accurately measure the microviscosity of human blood in microliter volumes obtained from healthy volunteers. An application of low-field L-band (1.2 GHz) EPR with a penetration depth of 1–2 cm allowed for microviscosity measurements using 13C-dFT in the living tissues from isolated organs and in vivo in anesthetized mice. In summary, this study demonstrates that EPR viscometry using a 13C-dFT probe can be used to noninvasively and rapidly measure the microviscosity of blood and interstitial fluids in living tissues and potentially to evaluate this biophysical marker of microenvironment under various physiological and pathological conditions in preclinical and clinical settings. 相似文献
975.
Petrik Galvosas Timothy I. Brox Stefan Kuczera 《Magnetic resonance in chemistry : MRC》2019,57(9):757-765
For over 25 years, nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) techniques have been used to study materials under mechanical deformation. Collectively, these methods are referred to as Rheo-NMR. In many cases, it provides spatially and temporally resolved maps of NMR spectra, intrinsic NMR parameters (such as relaxation times), or motion (such as diffusion or flow). Therefore, Rheo-NMR is complementary to conventional rheological measurements. This review will briefly summarize current capabilities and limitations of Rheo-NMR in the context of material science and food science in particular. It will report on recent advances such as the incorporation of torque sensors or the implementation of large amplitude oscillatory shear and point out future opportunities for Rheo-NMR in food science. 相似文献
976.
Loan T. T. Vo Fuad Hajji Barbora Široká Avinash P. Manian Adrienne Davis Timothy J. Foster Thomas Bechtold 《Cellulose (London, England)》2014,21(1):627-640
The paper is on introducing carbamate groups in sheets of cellulose fiber assemblies by pad-dry-cure treatments with aqueous solutions of polyethylene glycol, amide and salt. The effects of process variables—on carbamation levels and on mechanical properties of the substrate—are reported. Depending on treatment conditions, the nitrogen contents in substrates are in the range 0.668–2.252 wt%, corresponding to nominal degrees of carbamate group substitution of 0.08–0.28. The carbamation is initiated at 140 °C curing, and the levels rise with temperature up to 220 °C, but decrease at higher temperatures. The duration of curing also exerts an influence. There is a catalytic effect of sodium acetate on the carbamation, but the salt also induces a brown coloration in samples, which is likely a result of Maillard-type reactions. The treatments cause hydrolytic degradation in substrates, but there are options to adjust treatment conditions and minimize damage. Pad-dry-cure treatments are a common operation in the textile and paper industries, and the process may be adopted in commercial-scale operations to create derivatized paper or fabrics (woven, knitted or non-woven) for utilization in applications such as adsorbents for heavy metals from waste water, in hygiene products, in the creation of flame retardant products, or in creating all-cellulose composites by further treatment with alkali. 相似文献
977.
978.
Dr. Johannes C. L. Walker Dr. Simon Werrel Prof. Dr. Timothy J. Donohoe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(57):13114-13118
A photochemical approach to polysubstituted heterocycles using UV-induced alkene isomerization is described. The method allows for the synthesis of disubstituted furans and pyrroles under mild and neutral conditions and also provides access to a class of trisubstituted furans pertinent to natural-product synthesis. The method has broad functional-group tolerance and many richly decorated heterocycles have been prepared incorporating functional groups that are unstable under Brønsted and Lewis acidic conditions. 相似文献
979.
Yuchao Deng Xiao-Jing Wei Prof. Xiao Wang Prof. Dr. Yuhan Sun Prof. Dr. Timothy Noël 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(64):14532-14535
Transition-metal-catalyzed cross-coupling chemistry can be regarded as one of the most powerful protocols to construct carbon–carbon bonds. While the field is still dominated by palladium catalysis, there is an increasing interest to develop protocols that utilize cheaper and more sustainable metal sources. Herein, we report a selective, practical, and fast iron-based cross-coupling reaction that enables the formation of Csp−Csp3 and Csp2−Csp3 bonds. In a telescoped flow process, the reaction can be combined with the Grignard reagent synthesis. Moreover, flow allows the use of a supporting ligand to be avoided without eroding the reaction selectivity. 相似文献
980.