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1.
The role of π‐conjugated molecular bridges in through‐space and through‐bond electron transfer is studied by comparing two porphyrin–fullerene donor–acceptor (D–A) dyads. One dyad, ZnP–Ph–C60 (ZnP=zinc porphyrin), incorporates a phenyl bridge between D and A and behaves very similarly to analogous dyads studied previously. The second dyad, ZnP–EDOTV–C60, introduces an additional 3,4‐ethylenedioxythienylvinylene (EDOTV) unit into the conjugated bridge, which increases the distance between D and A, but, at the same time, provides increased electronic communication between them. Two essential outcomes that result from the introduction of the EDOTV unit in the bridge are as follows: 1) faster charge recombination, which indicates enhanced electronic coupling between the charge‐separated and ground electronic states; and 2) the disappearance of the intramolecular exciplex, which mediates photoinduced charge separation in the ZnP–Ph–C60 dyad. The latter can be interpreted as a gradual decrease in electronic coupling between locally excited singlet states of D and A when introducing the EDOTV unit into the D–A bridge.  相似文献   
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The existence of gas‐phase electrostatic ion–ion interactions between protonated sites on peptides ([Glu] Fibrinopeptide B, Angiotensin I and [Asn1, Val5]‐Angiotensin II) and attaching anions (ClO4? and HSO4?) derived from strong inorganic acids has been confirmed by CID MS/MS. Evidence for ion–ion interactions comes especially from the product ions formed during the first dissociation step, where, in addition to the expected loss of the anion or neutral acid, other product ions are also observed that require covalent bond cleavage (i.e. H2O loss when several carboxylate groups are present, or NH3 loss when only one carboxylate group is present). For [[Glu] Fibrinopeptide B + HSO4]?, under CID, H2O water loss was found to require less energy than H2SO4 departure. This indicates that the interaction between HSO4? and the peptide is stronger than the covalent bond holding the hydroxyl group, and must be an ion–ion interaction. The strength and stability of this type of ion‐pairing interaction are highly dependent on the accessibility of additional mobile charges to the site. Positive mobile charges such as protons from the peptide can be transferred to the attaching anion to possibly form a neutral that may depart from the complex. Alternatively, an ion–ion interaction can be disrupted by a competing proximal additional negatively charged site of the peptide that can potentially form a salt bridge with the positively charged site and thereby facilitate the attaching anion's departure. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
4.
The reaction of benzilmonoxime (BMOH) with CrCl3.6H2O in methanol gives the mono nuclear Cr(III) complex, [Cr(BMO)33 ( 1 ). Reaction of complex 1 with a methanolic solution of KOH at room temperature leads to a di‐nuclear Cr(III)‐Cr(III) complex, [Cr(BMO)2(OH)]2 ( 2 ). The complexes were characterized on the basis of their elemental analysis, Mass, IR, 1H and 13C‐NMR and electronic spectra. The IR studies were useful in assigning the coordination mode of the benzilmonoxime ligand to the chromium(III) ion. In addition, the presence of a hydroxo bridge in the dimeric complex 2 is inferred from the IR spectral studies. The electronic spectra of the complexes revealed two bands due to d–d transitions, and one band assignable to an oxygen (pπ)→Cr(eg*) LMCT transition observed in both complexes. An additional charge transfer transition, assignable to μ‐OH(pπ)→Cr(eg*), was only observed for the dimeric complex 2 . The splitting energy and Racah parameter were calculated to be 18484 cm‐1 and 560 cm‐1 for [Cr(BMO)3] ( 1 ), 17986 cm‐1 and 545 cm‐1 for [Cr(BMO)2(OH)]2 ( 2 ) respectively.  相似文献   
5.
通过分析惠斯登电桥测电阻的误差,提出改进实验方法提高灵敏度,减小测量误差.  相似文献   
6.
Dental pulp vitality is a desideratum for preserving the health and functionality of the tooth. In certain clinical situations that lead to pulp exposure, bioactive agents are used in direct pulp-capping procedures to stimulate the dentin-pulp complex and activate reparative dentinogenesis. Hydraulic calcium-silicate cements, derived from Portland cement, can induce the formation of a new dentin bridge at the interface between the biomaterial and the dental pulp. Odontoblasts are molecularly activated, and, if necessary, undifferentiated stem cells in the dental pulp can differentiate into odontoblasts. An extensive review of literature was conducted on MedLine/PubMed database to evaluate the histological outcomes of direct pulp capping with hydraulic calcium-silicate cements performed on animal models. Overall, irrespective of their physico-chemical properties and the molecular mechanisms involved in pulp healing, the effects of cements on tertiary dentin formation and pulp vitality preservation were positive. Histological examinations showed different degrees of dental pulp inflammatory response and complete/incomplete dentin bridge formation during the pulp healing process at different follow-up periods. Calcium silicate materials have the ability to induce reparative dentinogenesis when applied over exposed pulps, with different behaviors, as related to the animal model used, pulpal inflammatory responses, and quality of dentin bridges.  相似文献   
7.
This paper deals with the long‐term properties of the thermoelastic nonlinear string‐beam system related to the well‐known Lazer–McKenna suspension bridge model (0.1) In particular, no mechanical dissipation occurs in the equations, because the loss of energy is entirely due to thermal effects. The existence of regular global attractors for the associated solution semigroup is proved (without resorting to a bootstrap argument) for time‐independent supplies f,g,h and any . Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
8.
光学平衡桥式电流互感器的设计   总被引:1,自引:0,他引:1  
为了消除传感头随温度变化的线性双折射对光学电流互感器性能的影响,提出了光学平衡桥式电流互感器的概念,并给出了设计原理.推导了与温度有关的线性双折射导致的线偏振光方化角变化量的解析式,并计算了用1/2波片来消除线性双折射影响时波片光轴的方向.给出了光学平衡桥的工作原理和信号处理的方法,推导出计算电流的表达式.进行了实验研究,螺线管电流为2 A,温度在20℃-65℃范围变化时,所设计互感器的输出误差在2.96%以内.提出的光学平衡桥式电流互感器,解决了原有方法存在的线性双折射随温度变化对测量精度影响的难题,有利于促进光学电流互感器的实用化进程.  相似文献   
9.
非平衡电桥的输出特性研究   总被引:2,自引:0,他引:2  
研究了非平衡电桥的工作原理和输出特性,利用自组的实验装置进行了测量.  相似文献   
10.
为获知CFRP索斜拉桥的动力特性,推动CFRP索斜拉桥在我国的发展并积累经验,对国 内首座CFRP索斜拉桥分别进行了基于环境激励和锤击激励的结构动态特性测试研究,对不同 测试方案的试验结果进行了对比分析,结果表明脉动测试与锤击激励测试结果在对应的频率 值误差小、振型相似;环境激励测试法从测试的可行性、方便性及测试所得频率成分的组成 上较锤击激励测试法更为丰富.  相似文献   
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