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排序方式: 共有1590条查询结果,搜索用时 93 毫秒
1.
Pimchaya Luangaramvej Peeranuch Poungsripong Stephan Thierry Dubas 《Polymer International》2022,71(1):139-145
Polyelectrolyte complex (PEC) membranes prepared from poly(styrene sulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDADMAC) were modified by crossflow polymerization of aniline (ANI). The PEC membranes were used as separators in a two-compartment setup where ANI monomer and ammonium persulfate (APS) oxidant diffused through the membranes to form polyaniline (PANI). APS and ANI having different distributions throughout the membranes, the reaction led to the asymmetric polymerization of PANI on one face of each PEC membrane thus producing Janus membranes. Due to the excess PANI content, the membrane displayed distinct asymmetric electrical conductivities on each face. Interestingly, very different ANI polymerizations were obtained when nonstoichiometric PEC membranes having different molar ratio of cationic and anionic polyelectrolytes (P+:P? represents PDADMAC:PSS) were used and transport of APS was fastest through the 2:1 PEC when compared to the 1:2 PEC. In all experiments, the polymerization was most intense on the ANI side of the membranes. Also, the influence of NaCl both during PEC fabrication and during polymerization was studied and found to have some effect on the solute permeability. Results showed that a higher content of PANI was formed on PEC membranes having excess P+ and with no NaCl added during PEC fabrication. Although X-ray diffraction confirmed the presence of PANI on both sides of each membrane, scanning electron microscopy images demonstrated that both sides of each membrane had different PANI content deposited. Electrical conductivity measurements using a four-point probe setup also showed that the PEC–PANI exhibits asymmetric electrical property on different sides. © 2021 Society of Industrial Chemistry. 相似文献
2.
以丁二烯和苯乙烯为单体、正丁基锂为引发剂、双四氢糠丙烷为结构调节剂、1,1-二苯基乙烯为“盖帽剂”、烯丙基三甲氧基硅烷(TIOS)为封端剂,采用负离子聚合法合成了TIOS封端的溶聚丁苯橡胶(SSBR)。采用凝胶渗透色谱和核磁共振波谱表征了封端前后SSBR的结构和分子量及其分布,考察了封端反应时间、反应温度、TIOS用量及SSBR分子量对封端效率的影响。结果表明,封端反应时间为30 min、反应温度为60 ℃、TIOS与正丁基锂摩尔比为2.0及SSBR相对分子质量约为60 000时封端效率较高。 相似文献
3.
采用负离子溶液聚合法,以仲丁基锂为引发剂、环己烷为溶剂、四氢呋喃为结构调节剂,以及1,1-双(4-二甲基氨基苯基)乙烯为官能化共聚单体与丁二烯和苯乙烯进行活性负离子共聚合,制备了二甲氨基链中多官能化丁二烯-苯乙烯共聚物,考察了聚合温度和结构调节剂用量对聚合动力学和聚合物微观结构的影响。结果表明,共聚物链中二甲氨基官能团数量可通过调整聚合温度和结构调节剂用量进行准确控制,随聚合温度升高和四氢呋喃用量的增加,单体的总反应速率和转化率都逐渐增大;聚合物中1,2-结构的含量随结构调节剂用量的增加而逐渐增大,随聚合温度升高而逐渐减小。求得聚合温度为50 ℃时丁二烯和苯乙烯单体的平均竞聚率为69.67。 相似文献
4.
采用中燃油公司基质沥青进行阴离子乳化沥青的制备,并对固含量、乳化剂用量、稳定剂用量等多个因素进行试验研究。结果表明,随着固含量和乳化剂用量的增加,阴离子乳化沥青的标准黏度增加,常温储存稳定性变小。稳定剂的加入能够明显改善阴离子乳化沥青的常温储存稳定性,但标准黏度会有所增大。 相似文献
5.
Yuan Yue Ning Li Yang Ha Matthew J. Crafton Bryan D. McCloskey Wanli Yang Wei Tong 《Advanced functional materials》2021,31(14):2008696
Cation-disordered rocksalts (DRXs) have emerged as a new class of high-capacity Li-ion cathode materials. One unique advantage of the DRX chemistry is the structural flexibility that substantially lessens the elemental constraints in the crystal lattice, such as Li content, choice of transition metal redox center paired with appropriate d0 metal, and incorporation of F anion, which allows optimization of the key redox reactions. Herein, a series of the DRX oxyfluorides based on the Mn redox have been designed and synthesized. By tailoring the stoichiometry of the DRX compositions, high-capacity cycling by promoting the cationic Mn2+/Mn4+ redox reactions while suppressing those from anionic O is successfully demonstrated. A highly fluorinated DRX compound, Li1.2Mn0.625Nb0.175O1.325F0.675 (M0.625F0.675), delivers a capacity of ≈170 mAh g−1 at C/3 for 100 cycles. This work showcases the concept of balancing the cationic and anionic redox reactions in the DRX cathodes for improved electrochemical performance through the rational composition design. 相似文献
6.
Xinru Li Yue Tian Li Shen Zhibin Qu Tianqiong Ma Fei Sun Xiaoyan Liu Chen Zhang Jianqiang Shen Xianyang Li Lina Gao Shengxiong Xiao Taifeng Liu Yi Liu Yunfeng Lu 《Advanced functional materials》2021,31(22):2009718
Lithium (Li) metal batteries hold considerable promise for numerous energy-dense applications. However, the dendritic Li anode produced during Li+/Li deposition-stripping endangers battery safety and shortens cycle lifespan. Herein, an electrolyte interphase built from 2D anionic covalent organic frameworks (ACOF) is coated on Li for dendrite suppression. The ACOF with Li+-affinity facilitates rapid and exclusive passage of Li-ions from the electrolyte, yielding near-unity Li+ transference number (0.82) and ionic conductivity beyond 3.7 mS cm-1 at the interphase. Such high transport efficiency of Li-ions can fundamentally circumvent the Li+ deficiency that results in dendrite formation. Pairing the ACOF-coated Li against a high-voltage LiCoO2 cathode (4.5 V) achieves exceptional cycle stability, mitigated polarization, as well as improved rate capability. Accordingly, this strategy vastly expands the pool of electrolyte interphases that can be used for coating and protecting Li anode. 相似文献
7.
针对己内酰胺阴离子聚合反应特性,通过自行设计的适合该反应体系的树脂注射成型机和搭建的热塑性树脂传递模塑(T-RTM)成型实验平台,在恒压注射条件下,成功地制备了玻璃纤维(GF)体积分数高达48vol%的GF增强阴离子聚合尼龙6(APA-6)复合材料。研究了不同进料方式和压力、模具温度和纤维含量等工艺条件对GF/APA-6复合材料制品的表观质量、结晶度、热变形温度和力学性能的影响。结果表明,采取真空与加压相结合的进料方式并保持一定的溢流量,当注射压力在0.5~1.0 MPa时可以得到表面无缺陷、性能优异的制品;在模具温度为150℃时,GF/APA-6复合材料的弯曲强度和模量最高,分别达到682.7 MPa和24.4 GPa;而在180℃时,复合材料的层间剪切强度最高可达62.3 MPa。 相似文献
8.
某微细粒嵌布磁铁矿选矿工艺研究 总被引:1,自引:0,他引:1
针对某微细粒磁铁矿进行了全磁选流程和磁选-反浮选流程对比试验研究。结果表明,在最终磨矿细度相当的情况下,2种工艺流程都获得了产率48%左右、TFe品位66%左右、回收率80%左右的铁精矿指标,而采用磁选-反浮选流程的第三段磨矿量比全磁选流程减少了2/3。磁选-反浮选流程具有显著的节能降耗优势。 相似文献
9.
10.
This work aims to improve the rheological properties and stability of multiwalled carbon nanotubes (MWCNTs)/acrylamide (AA) base skeleton polymer blends at harsh environment of high salinity-high temperature (HS-HT) or various pH. Different co/terpolymers have been accomplished to modify the structure of AA polymer by free-radical copolymerization of AA-based monomers. Anionic, cationic, and hydrophobic functional groups were used for the synthesis of polyelectrolyte, polyampholytic, and partially hydrophobic AA polymer types. The conversion, molecular weight, and poly dispersity of co/terpolymers have been evaluated by nuclear magnetic resonance (1H-NMR), gel permeation chromatography, and differential scanning calorimetry analysis. The effects of sonication power, concentration of polymer, and concentration of MWCNTs were also investigated on rheological behavior of co/terpolymers. The results show that negative polyelectrolyte and polyampholytic polymers are the best candidates for the improvement of MWCNTs/polymer stability and viscosity at HS-HT and alkali environment, respectively. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47205. 相似文献