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91.
Chiral Schiff base complexes are very efficient for a wide range of reactions, including expoxidation[1], epoxide ring opening[2], Diels-Alder reaction[3], aldol reaction[4], etc. However, there are only few examples of P-N chelate Schiff bases being used as the chiral ligands in the asymmetric transfer hydrogenation of ketones. Recently, Gao et al[5] reported a series of P,N,N,P Schiff base ligands that have relatively low enantioselectivity in the asymmetric transfer hydrogenation of ketones. 相似文献
92.
不同波长紫外光照下纳米TiO2薄膜的光致亲水性与循环伏安行为 总被引:6,自引:1,他引:6
通过溶胶-凝胶方法分别在ITO和玻璃表面制备了纳米TiO_2薄膜,研究了纳米 TiO_2薄膜在254及365nm的紫外光照射下的循环伏安行为和光致超亲水性。在紫外 光的照射下,TiO_2薄膜电极可表现出两个光电化学过程,纳米TiO_2薄膜的光致超 亲水性转变及两个光电化学过程的速率均取决于紫外光的波长,原因在于纳米 TiO_2薄膜对两种波长的光的吸收率和光子的能量不同。提出了光电化学过程的机 理,认为紫外光照射下纳米TiO_2薄膜的超亲水性变化与产生Ti~(3+)的过程引起的 表面微观结构变化存在的一定的内在联系。 相似文献
93.
94.
Qing-shan Liang Jian-Gang Xie ChaoPing Yu ZhuSheng Feng JingChang Ma Yuan Zhang Dong Wang JianGuo Lu Ran Zhuang Jikai Yin 《Experimental & molecular medicine》2021,53(3):393
Splenectomy has been reported to improve liver fibrosis in patients with cirrhosis and hypersplenism. However, the mechanisms remain unclear. Tumor necrosis factor superfamily 14 (TNFSF14; also known as LIGHT) is highly expressed in the context of fibrosis and promotes disease progression in patients with fibrotic diseases such as pulmonary and skin fibrosis. Here, we determined whether splenectomy controls the production of LIGHT to improve liver fibrosis. Splenectomy reduced serum LIGHT levels in cirrhotic patients with hypersplenism and a ConA-induced liver fibrosis mouse model. Blocking LIGHT resulted in the downregulation of TGF-β1 in RAW264.7 cells. LIGHT treatment of RAW264.7 and JS1 cells in coculture regulated transforming growth factor-β1 (TGF-β1) expression through the activation of JNK signaling. Small interfering RNA-mediated silencing of lymphotoxin β receptor (LTβR) in macrophages resulted in pronounced decreases in the levels of fibrosis and αSMA in JS1 cells. These results indicated that LIGHT bound to LTβR and drove liver fibrosis in vitro. Blocking TGF-β1 abolished the effect of LIGHT in vitro. Furthermore, the administration of recombinant murine LIGHT protein-induced liver fibrosis with splenectomy, while blocking LIGHT without splenectomy improved liver fibrosis in vivo, revealing that the decrease in fibrosis following splenectomy was directly related to reduced levels of LIGHT. Thus, high levels of LIGHT derived from the spleen and hepatic macrophages activate JNK signaling and lead to increased TGF-β1 production in hepatic macrophages. Splenectomy attenuates liver fibrosis by decreasing the expression of LIGHT.Subject terms: Tumour-necrosis factors, Liver fibrosis, Hepatic stellate cells, Liver cirrhosis, Experimental models of disease 相似文献
95.
Poly(lactide-co-glycolide)-poly(ethylene glycol)-poly(lactide-co-glycolide)(PLGA-PEG-PLGA) triblock copolymer was synthesized through the ring-opening polymerization of LA and GA with PEG as macroinitiator and stannous octoate as catalyst. The amphiphilic copolymer self-assembled into micelles in aqueous solutions, and formed hydrogels as the increase of temperature at relatively high concentrations(〉 15 wt%). The favorable degradability of the hydrogel was confirmed by in vitro and in vivo degradation experiments. The good cellular and tissular compatibilities of the thermogel were demonstrated. The excellent adhesion and proliferation of bone marrow mesenchymal stem cells endowed PLGA-PEGPLGA thermogelling hydrogel with fascinating prospect for cartilage tissue engineering. 相似文献
96.
采用两步晶化法制备ZSM-5/MCM-48微介孔复合分子筛,通过调变前驱体溶胶的晶化时间获得不同结构的ZSM-5/MCM-48基分子筛催化剂。采用XRD、N2-吸附、SEM、TEM、FT-IR和Py-FTIR等手段进行表征,结果表明,前驱体溶胶的晶化时间对ZSM-5/MCM-48复合分子筛的结构和表面酸性产生重要的影响,而特定结构的复合分子筛基催化剂可以显著改变甲醇制汽油(MTG)反应的产物分布,与ZSM-5基催化剂相比显著降低了油品中芳烃和均四甲苯的含量。阐明了其催化作用机制是由于介孔结构的MCM-48对微孔结构的ZSM-5界面或表面的修饰作用。 相似文献
97.
Aluminum porphyrin complexes are heavy-metal-free and soil-tolerant green catalysts for the copolymerization of CO2 and propylene oxide (PO),but they suffer from relatively poor poly(propylene carbonate) (PPC) selectivity.Herein,steric hindrance porphyrin ligand was used to enhance the PPC selectivity.Typically,a bulky anthracene-like group was incorporated into the porphyrin ring to form 5,10,15,20-tetra(1,2,3,4,5,6,7,8-octahydro-1,4:5,8-dimethanoanthracen-9-yl)porphyrin,the aluminum porphyrin complex with this ligand,in combination with bis(triphenylphosphine)iminium chloride as a co-catalyst,produced completely alternate PPC.Additionally,the obtained PPC showed high regioselectivity,with a head-to-tail linkage content (HT) of 92%.Therefore,we demonstrated that introduction of bulky steric ligand into the porphyrin ring could reduce the propylene oxide homopolymerization activity leading to excellent PPC selectivity,and improve regioselectivity for the PO ring-opening during the copolymerization. 相似文献
98.
Huanrong Liu Mengqi Zhuang Zhanquan Zhang Xiaodong Dai Ling Qian Zifeng Yan 《Chemical Papers》2018,72(8):1973-1979
Soot removal for exhaust gas from diesel engine has been addressed due to the more stringent legislation and environmental concerns. MnCo2O4 catalysts were systematically prepared using glucose as a fuel via the auto-combustion method and applied for soot removal. The as-prepared samples were characterized by X-ray diffraction (XRD), O2-temperature-programmed oxidation (TPO) reaction and H2-temperature-programmed reduction reaction (H2-TPR). The catalytic activities for soot combustion were evaluated by micro activity test (MAT) with a tight contact mode between soot and catalysts. Compared with catalysts prepared by the solid state method without glucose, auto-combustion method in the presence of glucose can decrease the synthetic temperature, avoiding high temperature treatment and sintering. The catalysts prepared with glucose could catalyze soot oxidation effectively and the derived values of T10, T50, and T90 were 326, 408, and 468 °C in a tight contact mode, respectively, showing a significant drop of T10, T50, and T90 by 156, 177, and 178 °C for non-catalytic reaction. 相似文献
99.
Propagation of Enzyme‐Induced Surface Events inside Polymer Nanoassemblies for a Fast and Tunable Response 下载免费PDF全文
Dr. Jiaming Zhuang Dr. Hatice Seçinti Bo Zhao Prof. Dr. S. Thayumanavan 《Angewandte Chemie (International ed. in English)》2018,57(24):7111-7115
We report a new molecular design strategy that allows for the propagation of surface enzymatic events inside a supramolecular assembly for accelerated molecular release. The approach addresses a key shortcoming encountered with many of the currently available enzyme‐induced disassembly strategies, which rely on the unimer–aggregate equilibria of amphiphilic assemblies. The enzymatic response of the host to predictably tune the kinetics of guest‐molecule release can be programmed by controlling substrate accessibility through electrostatic complexation with a complementary polymer. Accelerated guest release in response to the enzyme is shown to be accomplished by a cooperative mechanism of enzyme‐triggered supramolecular host disassembly and host reorganization. 相似文献
100.
Phase‐Transition Induced Conversion into a Photothermal Material: Quasi‐Metallic WO2.9 Nanorods for Solar Water Evaporation and Anticancer Photothermal Therapy 下载免费PDF全文
Lei Sun Zhuo Li Rui Su Yuanlin Wang Zhenglin Li Baosheng Du Prof. Ye Sun Prof. Pengfei Guan Prof. Flemming Besenbacher Prof. Miao Yu 《Angewandte Chemie (International ed. in English)》2018,57(33):10666-10671
Phase transition from WO3 to sub‐stoichiometric WO2.9 by a facile method has varied the typical semiconductor to be quasi‐metallic with a narrowed band gap and a shifted Femi energy to the conduction band, while maintaining a high crystallinity. The resultant WO2.9 nanorods possess a high total absorption capacity (ca. 90.6 %) over the whole solar spectrum as well as significant photothermal conversion capability, affording a conversion efficiency as high as around 86.9 % and a water evaporation efficiency of about 81 % upon solar light irradiation. Meanwhile, the promising potential of the nanorods for anticancer photothermal therapy have been also demonstrated, with a high photothermal conversion efficiency (ca. 44.9 %) upon single wavelength near‐infrared irradiation and a high tumor inhibition rate (ca. 98.5 %). This study may have opened up a feasible route to produce high‐performance photothermal materials from well‐developed oxides. 相似文献