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991.
A free radical technique is described for the synthesis of tri- and multiblock copolymers of styrene and ethylene oxide through polyethylene oxide-based thermal “iniferters.” The mono- or dihydroxy-terminated oligomeric polyethylene oxides were chemically transformed to the secondary amine terminated species. Thiocarba-mylation and oxidation of the amine groups gave rise to macro- or polymeric thiuram disulfides called macro- or polymeric “iniferters,” respectively. Thermal polymerization of styrene in the presence of the macro iniferter led to the formation of their perfect triblock copolymers, with styrene forming the central block. Utilization of the polymeric iniferter, on the other hand, give rise to (A-B)n type segmented copolymers containing as many as 3 (A-B) sequences. The length of each block could be regulated by the choice of the appropriate iniferter and its relative concentration with respect to the monomer. The iniferters and the block copolymers were characterized. 相似文献
992.
993.
R. Agilandeswari A. Aditya Prasad S. Sivaraman S. Kalainathan 《Molecular Crystals and Liquid Crystals》2016,625(1):238-252
bis(2-nitroaniline) picrate (BNP) single crystals was grown by slow evaporation growth technique using mixed solvent system with methanol–acetone (1:1, v/v) at a constant temperature, and the structure was interpreted by single crystal X-ray, Power Diffraction (XRD) analysis. Inter- and intramolecular hydrogen bonding interactions were interpreted, and crystal cohesion was architectured by N-H···O, O-H···O, C-H···N, H···H, O···O, and π···π staking interactions. All intermolecular interactions occurring in the crystal lattice were calculated using fingerprint analysis. Interaction strengths were graphically illustrated by the Hirshfeld surface analysis. The band gap energy of BNP was estimated by the application of the Kubelka–Munk algorithm. Nonlinear optical behavior was confirmed by the Kurtz–Perry technique. Optimized geometry was derived by the density functional theory calculations. The first-order molecular hyperpolarizability (β) and excited state energies were estimated by the time-dependent density functional theory analysis. 相似文献
994.
Sreenath Nair Abigail Davis Olivia Campagne John D. Schuetz Clinton F. Stewart 《Molecules (Basel, Switzerland)》2022,27(17)
IWR-1-endo, a small molecule that potently inhibits the Wnt/β-catenin signaling pathway by stabilizing the AXIN2 destruction complex, can inhibit drug efflux at the blood–brain barrier. To conduct murine cerebral microdialysis research, validated, sensitive, and reliable liquid chromatography–tandem mass spectrometry (LC-MS/MS) methods were used to determine IWR-1-endo concentration in the murine plasma and brain microdialysate. IWR-1-endo and the internal standard (ISTD) dabrafenib were extracted from murine plasma and microdialysate samples by a simple solid-phase extraction protocol performed on an Oasis HLB µElution plate. Chromatographic separation was executed on a Kinetex C18 (100A, 50 × 2.1 mm, 4 µm particle size) column with a binary gradient of water and acetonitrile, each having 0.1% formic acid, pumped at a flow rate of 0.6 mL/min. Detection by mass spectrometry was conducted in the positive selected reaction monitoring ion mode by monitoring mass transitions 410.40 > 344.10 (IWR-1-endo) and 520.40 > 307.20 (ISTD). The validated curve range of IWR-1-endo was 5–1000 ng/mL for the murine plasma method (r2 ≥ 0.99) and 0.5–500 ng/mL for the microdialysate method (r2 ≥ 0.99). The lower limit of quantification (LLOQ) was 5 ng/mL and 0.5 ng/mL for the murine plasma and microdialysate sample analysis method, respectively. Negligible matrix effects were observed in murine plasma and microdialysate samples. IWR-1-endo was extremely unstable in murine plasma. To improve the stability of IWR-1-endo, pH adjustments of 1.5 were introduced to murine plasma and microdialysate samples before sample storage and processing. With pH adjustment of 1.5 to the murine plasma and microdialysate samples, IWR-1-endo was stable across several tested conditions such as benchtop, autosampler, freeze–thaw, and long term at −80 °C. The LC-MS/MS methods were successfully applied to a murine pharmacokinetic and cerebral microdialysis study to characterize the unbound IWR-1-endo exposure in brain extracellular fluid and plasma. 相似文献
995.
Pottathil Shinu Manu Sharma Girdhari Lal Gupta Somdutt Mujwar Mahmoud Kandeel Manish Kumar Anroop B. Nair Manoj Goyal Purna Singh Mahesh Attimarad Katharigatta N. Venugopala Sreeharsha Nagaraja Mallikarjun Telsang Bandar E. Aldhubiab Mohamed A. Morsy 《Molecules (Basel, Switzerland)》2022,27(20)
The 4-allyl guaiacol is a natural phenolic molecule that has been widely studied for its antioxidant capacity against reactive-oxygen-species-mediated cellular damage. Therefore, we hypothesized that concomitant use of an antioxidant and NSAID may decrease the risk of gastrointestinal toxicity and make the therapy safer. To address the gastrointestinal toxicity of conventional NSAIDs, a new S-naproxen-4-allyl guaiacol chimera (MAS-1696) was computationally developed, chemically synthesized, and tested for anti-inflammatory effectiveness and gastrointestinal safety. The inhibitory potency of MAS-1696 tested against cyclooxygenase-2 (COX2), 15-lipoxygenase-2 (15-LOX2), and lipoxygenase-5 (5-LOX) in vitro revealed a stronger inhibition of COX2. Furthermore, the MAS-1696 chimera increased the COX selectivity index by 23% as compared to the parent compound naproxen, implying higher efficacy and gastric safety. In vivo data showed that MAS-1696 was less likely to cause gastrointestinal harm than naproxen while also exerting anti-inflammatory and analgesic effects equivalent to or superior to naproxen. In conclusion, MAS-1696 is orally active, bio-labile, and crystalline, making it a medication that may be administered orally. 相似文献
996.
Harsh Kumar Meenu Singla Rajeev Jindal 《Monatshefte für Chemie / Chemical Monthly》2014,145(4):565-575
997.
This letter reports a study of a hybrid burst assembly and a hybrid burst loss recovery scheme (delay-based burst assembly and hybrid loss recovery (DBAHLR)) which selectively employs proactive or reactive loss recovery techniques depending on the classification of traffic into short term and long term, respectively. Traffic prediction and segregation of optical burst switching network flows into the long term and short term are conducted based on predicted link holding times using the hidden Markov model (HMM). The hybrid burst assembly implemented in DBAHLR uses a consecutive average-based burst assembly to handle jitter reduction necessary in real-time applications, with variations in burst sizes due to the non-monotonic nature of the average delay handled by additional burst length thresholding. This dynamic hybrid approach based on HMM prediction provides overall a lower blocking probability and delay and more throughput when compared with forward segment redundancy mechanism or purely HMM prediction-based adaptive burst sizing and wavelength allocation (HMM-TP). 相似文献
998.
This paper is concerned with the design of the sensorless controller for the position control of DC motor. The DC motor can be modeled as a linear time invariant single input single output system. In this paper synthesis and analysis of position control of a DC motor using sensor less fuzzy control and conventional PID controllers are carried out and their performance is evaluated and compared. The performance of sensor less fuzzy controller is found superior to conventional PID controllers even in the presence of disturbances. 相似文献
999.
Guanghui Zhu Christopher D. Hoffman Yang Liu Souryadeep Bhattacharyya Dr. Uma Tumuluri Melinda L. Jue Dr. Zili Wu Dr. David S. Sholl Dr. Sankar Nair Dr. Christopher W. Jones Dr. Ryan P. Lively 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(31):10743-10747
Both known and new CC3‐based porous organic cages are prepared and exposed to acidic SO2 in vapor and liquid conditions. Distinct differences in the stability of the CC3 cages exist depending on the chirality of the diamine linkers used. The acid catalyzed CC3 degradation mechanism is probed via in situ IR and a degradation pathway is proposed and supported with computational results. CC3 crystals synthesized with racemic mixtures of diaminocyclohexane exhibited enhanced stability compared to CC3‐R and CC3‐S. Confocal fluorescent microscope images reveal that the stability difference in CC3 species originates from an abundance of mesoporous grain boundaries in CC3‐R and CC3‐S, allowing facile access of aqueous SO2 throughout the crystal, promoting decomposition. These grain boundaries are absent from CC3 crystals made with racemic linkers. 相似文献
1000.