全文获取类型
收费全文 | 78283篇 |
免费 | 17753篇 |
国内免费 | 2438篇 |
专业分类
电工技术 | 4145篇 |
技术理论 | 3篇 |
综合类 | 2762篇 |
化学工业 | 22757篇 |
金属工艺 | 2389篇 |
机械仪表 | 3379篇 |
建筑科学 | 4643篇 |
矿业工程 | 1452篇 |
能源动力 | 1980篇 |
轻工业 | 10573篇 |
水利工程 | 1379篇 |
石油天然气 | 1584篇 |
武器工业 | 486篇 |
无线电 | 11533篇 |
一般工业技术 | 15678篇 |
冶金工业 | 2689篇 |
原子能技术 | 497篇 |
自动化技术 | 10545篇 |
出版年
2024年 | 267篇 |
2023年 | 884篇 |
2022年 | 1891篇 |
2021年 | 2651篇 |
2020年 | 3229篇 |
2019年 | 4490篇 |
2018年 | 4607篇 |
2017年 | 5244篇 |
2016年 | 5388篇 |
2015年 | 6111篇 |
2014年 | 6526篇 |
2013年 | 8034篇 |
2012年 | 6036篇 |
2011年 | 5771篇 |
2010年 | 5413篇 |
2009年 | 4907篇 |
2008年 | 4393篇 |
2007年 | 3936篇 |
2006年 | 3236篇 |
2005年 | 2663篇 |
2004年 | 2237篇 |
2003年 | 2027篇 |
2002年 | 1973篇 |
2001年 | 1661篇 |
2000年 | 1493篇 |
1999年 | 775篇 |
1998年 | 324篇 |
1997年 | 304篇 |
1996年 | 261篇 |
1995年 | 205篇 |
1994年 | 196篇 |
1993年 | 146篇 |
1992年 | 137篇 |
1991年 | 103篇 |
1990年 | 93篇 |
1989年 | 95篇 |
1988年 | 61篇 |
1987年 | 63篇 |
1986年 | 70篇 |
1985年 | 57篇 |
1984年 | 61篇 |
1983年 | 59篇 |
1982年 | 50篇 |
1981年 | 47篇 |
1980年 | 49篇 |
1979年 | 32篇 |
1978年 | 36篇 |
1977年 | 31篇 |
1976年 | 32篇 |
1975年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The Influence of Carbon Nitride Nanosheets Doping on the Crystalline Formation of MIL‐88B(Fe) and the Photocatalytic Activities 下载免费PDF全文
Zhen‐Dong Lei Yuan‐Cheng Xue Wen‐Qian Chen Lin Li Wen‐Hui Qiu Yong Zhang Liang Tang 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(35)
In this research, bulk graphitic carbon nitride (g‐C3N4) is exfoliated and transferred to the carbon nitride nanosheets (CNNSs), which are then coupled with MIL‐88B(Fe) to form the hybrid. From the results of the powder X‐ray diffraction, scanning electronic microscopy and thermogravimetric analysis, it is found that the doping of CNNSs on the surface of MIL‐88(Fe) could maintain the basic structure of MIL‐88B(Fe), and the smaller dimension of CNNSs might influence the crystallization process of metal‐organic frameworks (MOFs) compared to bulk g‐C3N4. Besides, the effects of the CNNSs incorporation on photocatalysis are also investigated. Through the photoluminescence spectra, electrochemical measurements, and photocatalytic experiments, the hybrid containing 6% CNNSs is certified to possess the highest catalytic activity to degrade methylene blue and reduce Cr(VI) under visible light. The improvement of the photocatalytic performance can be attributed to the matched energy level which favors the formation of the heterojunctions. Besides, it promotes the charge migration such that the contact between MOFs and CNNSs is more intimate, which can be inferred from the electronic microscopy images. Finally, a possible photocatalytic mechanism is put forward by the relative calculation and the employment of the scavengers to trap the active species. 相似文献
992.
993.
MXene Yarn Supercapacitors: High‐Performance Biscrolled MXene/Carbon Nanotube Yarn Supercapacitors (Small 37/2018) 下载免费PDF全文
994.
Highly Uniform Resistive Switching Properties of Solution‐Processed Silver‐Embedded Gelatin Thin Film 下载免费PDF全文
Yu‐Chi Chang Cheng‐Jung Lee Li‐Wen Wang Yeong‐Her Wang 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(13)
The silver‐embedded gelatin (AgG) thin film produced by the solution method of metal salts dissolved in gelatin is presented. Its simple fabrication method ensures the uniform distribution of Ag dots. Memory devices based on AgG exhibit good device performance, such as the ON/OFF ratio in excess of 105 and the coefficient of variation in less of 50%. To further investigate the position of filament formation and the role of each element, current sensing atomic force microscopy (CSAFM) analysis as well as elemental line profiles across the two different conditions in the LRS and HRS are analyzed. The conductive and nonconductive regions in the current map of the CSAFM image show that the conductive filaments occur in the AgG layer around Ag dots. The migration of oxygen ions and the redox reaction of carbon are demonstrated to be the driving mechanism for the resistive switching of AgG memory devices. The results show that dissolving metal salts in gelatin is an effective way to achieve high‐performance organic–electronic applications. 相似文献
995.
Green Synthesis of Hierarchically Porous Carbon Nanotubes as Advanced Materials for High‐Efficient Energy Storage 下载免费PDF全文
Jian‐Gan Wang Hongzhen Liu Xingyuan Zhang Xu Li Xingrui Liu Feiyu Kang 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(13)
Hierarchically porous carbon nanomaterials with well‐defined architecture can afford a promising platform for effectively addressing energy and environmental concerns. Herein, a totally green and straightforward synthesis strategy for the fabrication of hierarchically porous carbon nanotubes (HPCNTs) by a simple carbonization treatment without any assistance of soft/hard templates and activation procedures is demonstrated. A high specific surface area of 1419 m2 g?1 and hierarchical micro‐/meso‐/macroporosity can be achieved for the HPCNTs. The unique porous architecture enables the HPCNTs serving as excellent electrode/host materials for high‐performance supercapacitors and Li–sulfur batteries. The design strategy may pave a new avenue for the rational synthesis of hierarchically porous carbon nanostructures for high‐efficient energy storage applications. 相似文献
996.
Sheng Huang Chao Meng Min Xiao Shan Ren Shuanjin Wang Dongmei Han Yuning Li Yuezhong Meng 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(21)
Sodium ion batteries (SIB) are considered promising alternative candidates for lithium ion batteries (LIB) because of the wide availability and low cost of sodium, therefore the development of alternative sodium storage materials with comparable performance to LIB is urgently desired. The sodium ions with larger sizes resist intercalation or alloying because of slow reaction kinetics. Most pseudocapacitive sodium storage materials are based on subtle nanomaterial engineering, which is difficult for large‐scale production. Here, ferroelectric Sn2P2S6 with layered nanostructure is developed as sodium ion storage material. The ferroelectricity‐enhanced pseudocapacitance of sodium ion in the interlayer spacing makes the electrochemical reaction easier and faster, endowing the Sn2P2S6 electrode with excellent rate capability and cycle stability. Furthermore, the facile solid state reaction synthesis and common electrode fabrication make the Sn2P2S6 that becomes a promising anode material of SIB. 相似文献
997.
Fabricating Ir/C Nanofiber Networks as Free‐Standing Air Cathodes for Rechargeable Li‐CO2 Batteries 下载免费PDF全文
Chengyi Wang Qinming Zhang Xin Zhang Xin‐Gai Wang Zhaojun Xie Zhen Zhou 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(28)
Li‐CO2 batteries are promising energy storage systems by utilizing CO2 at the same time, though there are still some critical barriers before its practical applications such as high charging overpotential and poor cycling stability. In this work, iridium/carbon nanofibers (Ir/CNFs) are prepared via electrospinning and subsequent heat treatment, and are used as cathode catalysts for rechargeable Li‐CO2 batteries. Benefitting from the unique porous network structure and the high activity of ultrasmall Ir nanoparticles, Ir/CNFs exhibit excellent CO2 reduction and evolution activities. The Li‐CO2 batteries present extremely large discharge capacity, high coulombic efficiency, and long cycling life. Moreover, free‐standing Ir/CNF films are used directly as air cathodes to assemble Li‐CO2 batteries, which show high energy density and ultralong operation time, demonstrating great potential for practical applications. 相似文献
998.
999.
Nanoconfined Nickel@Carbon Core–Shell Cocatalyst Promoting Highly Efficient Visible‐Light Photocatalytic H2 Production 下载免费PDF全文
Ke Zhang Jingrun Ran Bicheng Zhu Huanxin Ju Jiaguo Yu Li Song Shi‐Zhang Qiao 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(38)
The realization of large‐scale solar hydrogen (H2) production relies on the development of high‐performance and low‐cost photocatalysts driven by sunlight. Recently, cocatalysts have demonstrated immense potential in enhancing the activity and stability of photocatalysts. Hence, the rational design of highly active and inexpensive cocatalysts is of great significance. Here, a facile method is reported to synthesize Ni@C core–shell nanoparticles as a highly active cocatalyst. After merging Ni@C cocatalyst with CdS nanorod (NR), a tremendously enhanced visible‐light photocatalytic H2‐production performance of 76.1 mmol g?1 h?1 is achieved, accompanied with an outstanding quantum efficiency of 31.2% at 420 nm. The state‐of‐art characterizations (e.g., synchrotron‐based X‐ray absorption near edge structure) and theoretical calculations strongly support the presence of pronounced nanoconfinement effect in Ni@C core–shell nanoparticles, which leads to controlled Ni core size, intimate interfacial contact and rapid charge transfer, optimized electronic structure, and protection against chemical corrosion. Hence, the combination of nanoconfined Ni@C with CdS nanorod leads to significantly improved photocatalytic activity and stability. This work not only for the first time demonstrates the great potential of using highly active and inexpensive Ni@C core–shell structure to replace expensive Pt in photocatalysis but also opens new avenues for synthesizing cocatalyst/photocatalyst hybridized systems with excellent performance by introducing nanoconfinement effect. 相似文献
1000.