首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   115058篇
  免费   12296篇
  国内免费   10776篇
化学   74629篇
晶体学   1264篇
力学   6273篇
综合类   673篇
数学   12858篇
物理学   42433篇
  2025年   100篇
  2024年   1279篇
  2023年   2377篇
  2022年   4066篇
  2021年   4668篇
  2020年   5134篇
  2019年   4841篇
  2018年   3750篇
  2017年   3357篇
  2016年   5143篇
  2015年   5033篇
  2014年   6181篇
  2013年   7849篇
  2012年   9341篇
  2011年   9556篇
  2010年   6657篇
  2009年   6378篇
  2008年   6707篇
  2007年   6005篇
  2006年   5603篇
  2005年   4708篇
  2004年   3737篇
  2003年   2953篇
  2002年   2693篇
  2001年   2256篇
  2000年   1964篇
  1999年   2070篇
  1998年   1747篇
  1997年   1565篇
  1996年   1578篇
  1995年   1386篇
  1994年   1256篇
  1993年   1024篇
  1992年   917篇
  1991年   792篇
  1990年   675篇
  1989年   527篇
  1988年   403篇
  1987年   349篇
  1986年   349篇
  1985年   269篇
  1984年   196篇
  1983年   159篇
  1982年   136篇
  1981年   88篇
  1980年   62篇
  1979年   28篇
  1978年   23篇
  1976年   25篇
  1957年   26篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
International Journal of Theoretical Physics - Quantum-dot is the result of elastic relaxation which has a straight relationship with the optical and electronic aspects of the quantum-dot-based...  相似文献   
104.
International Journal of Theoretical Physics - In this paper, we present a quantum key agreement (QKA) protocol with non-maximally entangled four-qubit cluster states. In our scheme, each...  相似文献   
105.
International Journal of Theoretical Physics - We propose a bidirectional controlled teleportation scheme using two pairs of Bell states as quantum channels. This solution uses Charlie as the...  相似文献   
106.
A novel series of ethyl 1,3‐disubstituted‐1,6‐dihydropyrrolo[2,3‐c]pyrazole‐5‐carboxylates can be rapidly and efficiently synthesized in excellent yields by condensing a variety of 1,3‐substituted‐4‐formyl‐5‐chloropyrazole with ethyl isocyanoacetate in the presence of 1‐methyl‐3‐butylimidazolium hydroxide under microwave irradiation. The simple experimental procedure, DMSO‐free condition, short period of conversion, and excellent yields are the advantages of the present method. The structures of the novel compounds are confirmed by IR, 1H NMR, 13C NMR, MALDI‐TOF MS, and elemental analysis.  相似文献   
107.
We have combined the molecular imprinting and the layer-by-layer assembly techniques to obtain molecularly imprint polymers (MIPs) for the electrochemical determination of p-nitrophenol (p-NPh). Silica microspheres functionalized with thiol groups and gold nanoparticles (Au-NPs) were assembled on a gold electrode surface layer by layer. The electrode was then immersed into a solution of pyrrole and p-NPh (the template), and electropolymerization led to the creation of a polymer-modified surface. After the removal of the silica spheres and the template, electrochemical impedance spectroscopy and differential pulse voltammetry (DPV) were employed to characterize the surface. The results demonstrated the successful fabrication of macroporous MIPs embedded with Au-NPs on the gold electrode. The effects of monomer concentration and scan rate on the performance of the electrode were optimized. Excellent recognition capacity is found for p-NPh over chemically similar species. The DPV peak current is linearly related to concentration of p-NPh in the 0.1 μM to 1.4 mM range, with a 0.1 μM limit of detection (at S/N?=?3).
Figure
Molecularly imprinted polymers (MIPs) and nanomaterials were combined to prepare a novel macroporous structured MIPs based electrochemical sensor for the investigation of an environmental pollutant, p-nitrophenol (p-NPh). The sensor exhibited a fast binding dynamics, good specific adsorption capacities, and high selective recognition to p-NPh.  相似文献   
108.
The single or co-combustion experiments of high-Ca pyrolyzed biochar and high-Si coal were carried out on a drop tube furnace (DTF) at 1300 °C under air and oxyfuel (CO2:O2=50:50, oxy50) conditions. The produced PM10 (of an aerodynamic diameter of 10 µm or less) was analyzed to investigate the interactions during co-combustion. Due to the characteristics of the selected samples (low S and Cl), the PM1 emissions including PM0.1 and PM0.1–1 are very low during single combustion, except for the PM0.1–1 emission during the combustion of biochar under oxy50 condition because of the massive partitioning of Mg, Ca and Fe. The interaction during co-combustion was observed to mainly occur in the generation of PM1–10, and also slightly occur in the formation of PM0.1–1 under oxy50 condition. The capture of Mg, Ca, and Fe from biochar by the Si-containing minerals in coal under the oxy50 condition results in a slight decrease in PM0.1–1 during co-combustion. The higher the proportion of coal blended, the more obvious the reduction of elements. As for the formation of PM1–10 during co-combustion, high-melting minerals of biochar would weaken the coalescence of minerals in coal to cause more PM10, while the large mineral grains of coal would capture the minerals in biochar to generate more PM10+. Under the competition of the above two types of interactions, the experimental value of PM1–10 yields was almost consistent with the theoretically calculated value, except for blended ratio of 80:20 (coal: biochar, air) or 50:50 (oxy50) with prior interaction predominating.  相似文献   
109.
Two-dimensional surface-enhanced Raman scattering(SERS) substrates have drawn intense attention due to their excellent spectral reproducibility, high uniformity and perfect anti-interference ability. However, the inferior detection sensitivity and low enhancement have limited the practical application of two-dimensional SERS substrates. To address this issue, we propose that the interaction between the MoTe_2 substrate and the analyte rhodamine 6 G molecules could be remarkably enhanced by the introduced p-doping effect and lattice distortion of MoTe_2 via hydrogen plasma treatment. After the treatment, the SERS is greatly improved, the enhancement factor of probe molecules reaches 1.83 × 10~6 as well as the limit of detection concentration reaches 10-13 M.This method is anticipated to afford new enhancement probability for other 2D materials, even non-metal oxide semiconductor SERS substrates.  相似文献   
110.
Main observation and conclusion Anode materials based on conversion reactions usually possess high energy densities for lithium-ion batteries (LIBs).However,the...  相似文献   
[首页] « 上一页 [6] [7] [8] [9] [10] 11 [12] [13] [14] [15] [16] 下一页 » 末  页»
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号