全文获取类型
收费全文 | 16669篇 |
免费 | 696篇 |
国内免费 | 51篇 |
专业分类
化学 | 11143篇 |
晶体学 | 264篇 |
力学 | 519篇 |
综合类 | 1篇 |
数学 | 1366篇 |
物理学 | 4123篇 |
出版年
2024年 | 49篇 |
2023年 | 178篇 |
2022年 | 356篇 |
2021年 | 437篇 |
2020年 | 508篇 |
2019年 | 567篇 |
2018年 | 533篇 |
2017年 | 492篇 |
2016年 | 736篇 |
2015年 | 518篇 |
2014年 | 804篇 |
2013年 | 1394篇 |
2012年 | 1209篇 |
2011年 | 1261篇 |
2010年 | 829篇 |
2009年 | 645篇 |
2008年 | 799篇 |
2007年 | 807篇 |
2006年 | 635篇 |
2005年 | 555篇 |
2004年 | 436篇 |
2003年 | 365篇 |
2002年 | 292篇 |
2001年 | 195篇 |
2000年 | 174篇 |
1999年 | 121篇 |
1998年 | 98篇 |
1997年 | 120篇 |
1996年 | 118篇 |
1995年 | 92篇 |
1994年 | 113篇 |
1993年 | 127篇 |
1992年 | 147篇 |
1991年 | 109篇 |
1990年 | 109篇 |
1989年 | 100篇 |
1988年 | 76篇 |
1987年 | 69篇 |
1986年 | 68篇 |
1985年 | 89篇 |
1984年 | 98篇 |
1983年 | 82篇 |
1982年 | 77篇 |
1981年 | 64篇 |
1980年 | 64篇 |
1979年 | 95篇 |
1978年 | 80篇 |
1977年 | 78篇 |
1976年 | 60篇 |
1975年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
941.
Effect of Temperature and Discharge Rate on Electrochemical Performance of Fiber Nickel–Cadmium Cell
Senthilkumar M. Satyavani T. V. S. L. Raman M. Venkat Sahoo P. K. Kumar A. Srinivas 《Russian Journal of Electrochemistry》2022,58(1):43-49
Russian Journal of Electrochemistry - The effect of temperature and discharge rate on the discharge capacity of nickel–cadmium (Ni?Cd) cell is investigated quantitatively. Ni–Cd... 相似文献
942.
Bommireddy Naveen Palathedath Suresh Kumar 《Journal of Solid State Electrochemistry》2022,26(12):2733-2742
Journal of Solid State Electrochemistry - The development of materials with high active surface area/surface modification is of great interest in electrochemistry due to their widespread... 相似文献
943.
Lakshminarayanan Gowtham Das Ujjalkumar Laxmi Moksha Tapas Kumar Roy Nabanita Halder Thirumurthy Velpandian 《Journal of separation science》2022,45(6):1210-1221
4-Hydroxy isoleucine is one of the potent hypoglycemic active constituents of fenugreek seeds. A method capable of reducing biological interferences is required for bioavailability studies. An isocratic separation of 4-hydroxy isoleucine from endogenous interferences was achieved in ZIC-cHILIC column using 0.1% formic acid in water and acetonitrile (20:80, % v/v) pumped at 0.5 ml/min. Quantification was performed in multiple reaction monitoring mode using the transitions of m/z 148.1→102.1 and m/z 276.1→142.2 for 4-hydroxy isoleucine and homatropine (as internal standard), respectively. After full method validation, 4-hydroxy isoleucine levels in human plasma and commercial fenugreek formulations were determined. This method showed good linearity in the range of 50–2000 ng/mL. Intra- and interday accuracies were in the range of 90.64–109.0% and precision was <4.82% CV. The mean (SD) plasma concentration of 4-hydroxy isoleucine in healthy individuals at 2 h after oral administration of fenugreek tablet was found to be 1590 (260) ng/mL. Half of marketed formulations were found to contain <0.05% of 4-hydroxy isoleucine content. We developed a rapid hydrophilic interaction liquid chromatography–tandem mass spectrometry method for analysis of 4-hydroxy isoleucine in human plasma. This method can be applied directly to conduct the clinical pharmacokinetics studies of 4-hydroxy isoleucine in human population. 相似文献
944.
Herein, we report a facile method for synthesizing MoCo-layered double hydroxide (LDH) nanosheets employing Prussian blue analog (PBA) as the precursor. The introduction of Mo in Co-LDH modulates the electronic structure, increases the number of active sites and electrochemical surface area to improve the hydrogen evolution, oxygen evolution, and overall water splitting activity. As a result, PBA-derived Mo0.25Co0.75-LDH nanosheets demonstrated 10 mA cm?2 current density at only 220 mV and 115 mV overpotentials for OER and HER, respectively. The overall water splitting was attained at 1.52 V cell voltage for 10 mA cm?2 current density. 相似文献
945.
G. Yasin S. Ibraheem S. Ali M. Arif S. Ibrahim R. Iqbal A. Kumar M. Tabish M.A. Mushtaq A. Saad H. Xu W. Zhao 《Materials Today Chemistry》2022
Controllable tailoring of metal-free/carbon-based nanostructures tends an encouraging way to enhance the bifunctional activity of electrodes, but a great challenge owing to the sluggish kinetics of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, a facile tempted-defects assisted fractionation strategy is presented to synthesize N, S, and O tri-doped metal-free catalyst (DE-TDAP). Due to this effective tempted-defects and heteroatoms interlinking in DE-TDAP, it delivers the lowest overpotential toward both the OER (346 mV) and HER (154 mV) at 10 mA cm?2. Remarkably, the DE-TDAP-electrode carries only a cell voltage of 1.81 V at 10 mA cm?2 for overall water splitting and long-term stability. Considerably, the density functional theory (DFT) calculation exposes that the tailored-defects in tri-doped interlinking could enhance bifunctional catalytic performance devising from lower Gibbs free energy of OER/HER intermediates on active sites. This struggle henceforth provides a perceptive understanding of the synergetic principles of heteroatom-interlinking-tailoring nanostructures in water splitting. 相似文献
946.
Sabine Briede Anda Barkane Maksims Jurinovs Vijay Kumar Thakur Sergejs Gaidukovs 《Current Opinion in Green and Sustainable Chemistry》2022
Over the years, eco-friendly raw biomass is being investigated to develop novel green monomer and oligomer components for sustainable polymer materials synthesis. The use of naturally obtained biomass can reduce the dependence on petrochemical suppliers and the impact of petroleum prices. Polymer materials obtained from biomass are a competitive alternative comparing with those made from petrochemicals. Domestically and industrially used vegetable oil derivatives are considered widely available, while cellulose derivatives are the most abundant natural polymers. Biobased acrylic polymers developed from vegetable oils and cellulose are very popular nowadays. Using acrylic derivatives of vegetable oils and cellulose as naturally obtained materials leads to long-lasting biopolymers with a wide range of high exploitation properties and applications. The characteristics of vegetable oil- and cellulose-based acrylate resins of high-biorenewable carbon content are suitable for industrial application, while their role is still underestimated. A brief analysis of biomass-derived biopolymer resin compositions, properties, and applications is critically outlined herein. 相似文献
947.
Ashwani Kumar Sahanaz Parvin Dr. Raj Kumar Das Prof. Sayan Bhattacharyya 《化学:亚洲杂志》2021,16(21):3444-3452
Metal-organic coordination polymers (CP) have attracted the scientific attention for electrochemical water oxidation as it has the similar coordination structure like natural photosynthetic coordinated complex. However, the harsh synthesis conditions and bulky nature pose a major challenge in the field of catalysis. Herein, 3–5 nm CP particles synthesized at room temperature using aqueous solutions of Ni2+/Cu2+ and 2,5-dihydroxyterepthalic acid as precursor were applied for alkaline water and urea electrolysis. The overpotential required is only 300 mV at 10 mA cm−2 by Nano-Ni CP for water oxidation, with turnover frequency (TOF) of 21.4 s−1 which is around 8 times higher than its bulk-counterpart. Overall water and urea splitting were achieved with Nano-Cu (−) ∥ Nano-Ni (+) couple on Ni foam at 1.69 and 1.52 V to achieve 10 mA cm−2, respectively. High electrochemical surface area (ECSA), high TOF, and enhanced mass diffusion are found to be the key parameters responsible for the state-of-the-art water and urea splitting performances of nano-CPs as compared to their bulk counterparts. 相似文献
948.
Vartika Srivastava Manukonda Suresh Kumar Puthiya Veetil Nidheesh Carlos A. Martínez-Huitle 《Current Opinion in Electrochemistry》2021
Use of robust and safe water disinfection technologies which are inexpensive and energy-efficient are need of the hour to combat the problem of inadequate access of safe and clean drinking water. Energy and chemically intensive water treatment technologies warrant the need for a safe and environmentally sound treatment technology. Electrochemical disinfection or electrodisinfection (ED) is experiencing a great resurgence among the scientific communities owing to its novel use of electrode materials and electric current in an inexpensive and energy-efficient way for achieving the inactivation of microorganisms. Among the various electrodes used in the ED, boron-doped diamonds emerge as a sustainable alternate for their ability to electro generate strong potent oxidants which result in effective pathogen control in drinking water. ED for disinfecting waters occurs via generation of the reactive species which act in the bacterial inactivation mechanisms. In this mini-review, a critical discussion on the fundamentals and applications of promising electrochemical methods using boron-doped diamond anodes (namely electrochemical oxidation), evidencing their advantages for the remediation of drinking water infected with waterborne agents, is given. 相似文献
949.
Hao-Lin Hsu Milon Miah Shyamal Kumar Saha Jean-Hong Chen Lung-Chuan Chen Sheng-Yen Hsu 《Materials Today Chemistry》2021
Bundle-type mutil-walled carbon nanotubes (MWCNTs) composite electrode is the first investigation and publication for the supercapacitor application. According to the thermogravimetric analysis results, as-synthesized BCNTs are considered as the electrode materials for supercapacitors and electrochemical double-layer capacitor in this study. The Brunauer–Emmett–Teller specific surface area of as-prepared bundled carbon nanotubes (BCNTs) is 95.29 m2/g given to a type III isotherm and H3 hysteresis loops. Slow scanning rates promote and enhance to achieve high Cb because of the superior conductivity of CNT bundles and one side close-layered Ni/Mg/Mo alloy inside the BCNT-based electrode and facile electron diffusivity between electrolyte and electrode. The specific capacitance Cs (1,560 F/g) is nearly equal to the maximum specific capacitance, which the BCNT-based composite electrode can actually be able to charge or fill in. The maximum energy density value is 195 Wh/kg with corresponding power density values of 0.21 kW/kg. Furthermore, the active 3D BCNTs material fabricated electrode enhances to contact the electrolyte directly and decreases the ion diffusion limitation. Electrochemical impedance spectroscopy spectrum summarized as the low-frequency area controls by mass transfer limitation, and the high-frequency area dominates by charge transfer of kinetic control. After 2,000 consecutive cyclic voltammetry sacnings and galvanostatic charge-discharge cycles at a current density of 1.67 A/g performs, the specific capacitance retentions of 3D BCNTs electrodes achieved 128.2 and 77.3%, respectively. Three-dimensional BCNT composite electrodes exhibit good conductivity and low charge transfer resistance, which is beneficial to fast charge transfer between the BCNTs electrode materials and electrolytes. 相似文献
950.
Venkatachalam Rajagopal Nivedhitha Jothi Narayanan Murugavel Kathiresan Deepak Kumar Pattanayak Vembu Suryanarayanan 《Materials Today Chemistry》2021
Herein, we report the synthesis of new covalent organic polymer comprising triazine and o-tolidine by solvothermal method. The formation of polymer was confirmed by Fourier transform infra red spectroscopy (FT-IR), cross polarization–magic angle spinning nuclear magnetic resonance (NMR), transmission electron microscopy, and scanning electron microscopy. Their antibacterial activity toward S. aureus (gram-positive) and P. aeruginosa (gram-negative) was assessed by the optical density measurements and direct contact method. These results have great significance toward the design of new porous polymers for antibacterial applications. 相似文献