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991.
AlOOH在一氧化碳加氢反应中结构与性能的研究 《燃料化学学报》2016,44(7):830-836
采用沉淀水热法,通过调变水热过程中水与凝胶的质量比制备了不同的AlOOH,将其与工业甲醇催化剂C302混合形成复合催化剂,考察复合催化剂对一氧化碳加氢的影响,同时运用XRD、FT-IR、BET、NH_3-TPD-M S、TG-DTG和H_2-TPR等技术对不同AlOOH进行了表征。结果表明,水热过程中水与凝胶的质量比对AlOOH择优取向晶面、孔结构、表面酸强度等存在明显影响,进而导致复合催化剂产物中出现分布不同的低碳醇或二甲醚。其中,当水和凝胶的质量比为2∶1时,AlOOH的(020)和(120)晶面择优取向,孔容增大,且其表面具有适宜的强弱酸比例中心,复合催化剂呈现出较高的低碳醇选择性,表明AlOOH具有碳链增长的作用,这为合成气制取低碳醇催化剂提供了新的思路。 相似文献
992.
Wen‐Neng Wu Man‐Ni Gao Hong Tu Gui‐Ping Ouyang 《Journal of heterocyclic chemistry》2016,53(6):2042-2048
A series of novel N‐substituted‐2‐(6‐morpholino‐9H‐purin‐9‐yl)acetamide and 4‐(9‐((5‐substituted‐1,3,4‐oxadiazole/thiadiazole‐2‐yl)methyl)‐9H‐purin‐6‐yl)‐morpholine derivatives were synthesized and evaluated their antibacterial activities against rice bacterial leaf blight and tobacco bacterial wilt caused by Xanthomonas oryzae pv. oryzae (Xoo) and Ralstonia solanacearum (R. solanacearum) via the turbidimeter test in vitro. Antibacterial bioassay indicated that most compounds demonstrated good inhibitory effect against Xoo and R. solanacearum. Especially, compound 6a demonstrated the best inhibitory effect against Xoo with half‐maximal effective concentration (EC50) value of 8.39 μg/mL, which was even better than those of commercial agents Bismerthiazol and Thiodiazole copper. The synthesized purine derivatives containing amide and 1,3,4‐oxadiazole/thiadiazole moieties exhibited excellent antibacterial activities against Xanthomonas oryzae pv. oryzae and R. solanacearum in vitro. 相似文献
993.
994.
设a≥2是正整数.本文证明了:当a=2时,方程X~2一(a~2+1)Y~4=3-4a仅有正整数解(X,Y)=(20,3);当a=3时,该方程仅有2组互素的正整数解(X,Y)=(1,1)和(79,5);当a≥4且4a+1非平方数时,该方程最多有4组互素的正整数解(X,Y);当a≥4且4a+1为平方数时,该方程最多有5组互素的正整数解(X,Y). 相似文献
995.
996.
Thermally Induced Intra‐Carboxyl Proton Shuttle in a Molecular Rack‐and‐Pinion Cascade Achieving Macroscopic Crystal Deformation
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Dr. You‐Gui Huang Yoshihito Shiota Sheng‐Qun Su Shu‐Qi Wu Zi‐Shuo Yao Guo‐Ling Li Shinji Kanegawa Soonchul Kang Takashi Kamachi Kazunari Yoshizawa Prof. Katsuhiko Ariga Prof. Osamu Sato 《Angewandte Chemie (International ed. in English)》2016,55(47):14628-14632
Proton transport via dynamic molecules is ubiquitous in chemistry and biology. However, its use as a switching mechanism for properties in functional molecular assemblies is far less common. In this study, we demonstrate how an intra‐carboxyl proton shuttle can be generated in a molecular assembly akin to a rack‐and‐pinion cascade via a thermally induced single‐crystal‐to‐single‐crystal phase transition. In a triply interpenetrated supramolecular organic framework (SOF), a 4,4′‐azopyridine (azpy) molecule connects to two biphenyl‐3,3′,5,5′‐tetracarboxylic acid (H4BPTC) molecules to form a functional molecular system with switchable mechanical properties. A temperature change reversibly triggers a molecular movement akin to a rack‐and‐pinion cascade, which mainly involves 1) an intra‐carboxyl proton shuttle coupled with tilting of the azo molecules and azo pedal motion and 2) H4BPTC translation. Moreover, both the molecular motions are collective, and being propagated across the entire framework, leading to a macroscopic crystal expansion and contraction. 相似文献
997.
Determination of arsenic species in Solanum Lyratum Thunb using capillary electrophoresis with inductively coupled plasma mass spectrometry
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Pei‐Yu Shuai Xiao‐Jun Yang Zong‐Qing Qiu Xiao‐Hui Wu Xi Zhu Ganga Raj Pokhrel Yu‐Ying Fu Hui‐Min Ye Wen‐Xiong Lin Gui‐Di Yang 《Journal of separation science》2016,39(16):3239-3245
A simple and highly efficient interface to couple capillary electrophoresis with inductively coupled plasma mass spectrometry by a microflow polyfluoroalkoxy nebulizer and a quadruple ion deflector was developed in this study. By using this interface, six arsenic species, including arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, and arsenocholine, were baseline‐separated and determined in a single run within 11 min under the optimized separation conditions. The instrumental detection limit was in the range of 0.02–0.06 ng/mL for the six arsenic compounds. Repeatability expressed as the relative standard deviation (n = 5) of both migration time and peak area were better than 2.5 and 4.3% for six arsenic compounds. The proposed method, combined with a closed‐vessel microwave‐assisted extraction procedure, was successfully applied for the determination of arsenic species in the Solanum Lyratum Thunb samples from Anhui province in China with the relative standard deviations (n = 5) ≤4%, method detection limits of 0.2–0.6 ng As/g and a recovery of 98–104%. The experimental results showed that arsenobetaine was the main speciation of arsenic in the Solanum Lyratum Thunb samples from different provinces in China, with a concentration of 0.42–1.30 μg/g. 相似文献
998.
Crystal polymorphism of protein GB1 examined by solid-state NMR spectroscopy and X-ray diffraction 总被引:1,自引:0,他引:1
Schmidt HL Sperling LJ Gao YG Wylie BJ Boettcher JM Wilson SR Rienstra CM 《The journal of physical chemistry. B》2007,111(51):14362-14369
The study of micro- or nanocrystalline proteins by magic-angle spinning (MAS) solid-state NMR (SSNMR) gives atomic-resolution insight into structure in cases when single crystals cannot be obtained for diffraction studies. Subtle differences in the local chemical environment around the protein, including the characteristics of the cosolvent and the buffer, determine whether a protein will form single crystals. The impact of these small changes in formulation is also evident in the SSNMR spectra; however, the changes lead only to correspondingly subtle changes in the spectra. Here, we demonstrate that several formulations of GB1 microcrystals yield very high quality SSNMR spectra, although only a subset of conditions enable growth of single crystals. We have characterized these polymorphs by X-ray powder diffraction and assigned the SSNMR spectra. Assignments of the 13C and 15N SSNMR chemical shifts confirm that the backbone structure is conserved, indicative of a common protein fold, but side chain chemical shifts are changed on the surface of the protein, in a manner dependent upon crystal packing and electrostatic interactions with salt in the mother liquor. Our results demonstrate the ability of SSNMR to reveal minor structural differences among crystal polymorphs. This ability has potential practical utility for studying the formulation chemistry of industrial and therapeutic proteins, as well as for deriving fundamental insights into the phenomenon of single-crystal growth. 相似文献
999.
A new fluorescent dye, N-allyl-4-morpholinyl-1,8-naphthalimide (AMN), was synthesized as a fluorescence indicator in the fabrication of a sensor for
determining water content in organic solvents. To prevent leakage of the fluorophore, AMN was photo-copolymerized with acrylamide,
(2-hydroxyethyl)methacrylate, and triethylene glycol dimethacrylate on a glass surface treated with a silanizing agent. The
sensing mechanism is based on the solvatochromic feature of the covalently immobilized AMN. The fluorescence intensity of
AMN decreased with increasing water contents when it was excited at 400 nm. In the range of ca. 0.00–4.40% (v/v), the fluorescence
intensity of AMN changed as a linear function of water content. The sensor exhibited satisfactory reproducibility, reversibility,
and a response time (t
99) of the order of 50 s. The detection limit was solvent-dependent, when acetonitrile was used as the solvent, and the detection
limit could be as low as 0.006% (v/v) of water. Additionally, the prepared sensor is pH-insensitive and possesses a relatively
long lifetime of at least one month. 相似文献
1000.
Fluorescence enhancements of benzene-cored luminophors by restricted intramolecular rotations: AIE and AIEE effects 总被引:3,自引:0,他引:3
Zeng Q Li Z Dong Y Di C Qin A Hong Y Ji L Zhu Z Jim CK Yu G Li Q Li Z Liu Y Qin J Tang BZ 《Chemical communications (Cambridge, England)》2007,(1):70-72
Photoluminescence of simple arylbenzenes with ready synthetic accessibility is enhanced by two orders of magnitude through aggregate formation; viscosity and temperature effects indicate that the emission enhancement is due to the restriction of their intramolecular rotations in the solid state. 相似文献