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101.
Milda Nainytė Felix Müller Giacomo Ganazzoli Chun-Yin Chan Antony Crisp Dr. Daniel Globisch Prof. Dr. Thomas Carell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(65):14856-14860
Fossils of extinct species allow us to reconstruct the process of Darwinian evolution that led to the species diversity we see on Earth today. The origin of the first functional molecules able to undergo molecular evolution and thus eventually able to create life, are largely unknown. The most prominent idea in the field posits that biology was preceded by an era of molecular evolution, in which RNA molecules encoded information and catalysed their own replication. This RNA world concept stands against other hypotheses, that argue for example that life may have begun with catalytic peptides and primitive metabolic cycles. The question whether RNA or peptides were first is addressed by the RNA-peptide world concept, which postulates a parallel existence of both molecular species. A plausible experimental model of how such an RNA-peptide world may have looked like, however, is absent. Here we report the synthesis and physicochemical evaluation of amino acid containing adenosine bases, which are closely related to molecules that are found today in the anticodon stem-loop of tRNAs from all three kingdoms of life. We show that these adenosines lose their base pairing properties, which allow them to equip RNA with amino acids independent of the sequence context. As such we may consider them to be living molecular fossils of an extinct molecular RNA-peptide world. 相似文献
102.
对近十年来化学计量学在生命科学领域相关研究中的应用进行了综述,主要对其在DNA、蛋白质及氨基酸这三大生命物质有关研究中的使用展开了评述和讨论,参考文献59篇。 相似文献
103.
CoSi is an inexpensive thermoelectric material for medium temperature (200–500 °C). Its power factor is as large as the state of the art materials; however, its thermal conductivity is too large. Then, improving its thermoelectric performances implies increasing the scattering of phonons, which can be performed by nanostructuring the material. In this paper we investigate the effect of nanostructuration on the structure, microstructure, lattice dynamics and stability of CoSi. We obtained powders of about 13 nm by mechanical milling bulk CoSi for only four hours or by mechanical alloying pure elements for twelve hours. Nanostructuration induces a 0.1% expansion of the lattice parameter. Raman spectroscopy, associated to ab initio calculations, highlights the effectiveness of nanostructuration on phonon scattering, showing a reduction of the phonon relaxation time by as much as 80%. Powders are stable up to 450 °C; then grains coarsen and a partial degradation of the material occurs, probably due to silicon sublimation. Our results indicate that nanostructuration should be considered when interested to reduce CoSi thermal conductivity. 相似文献
104.
Surendra V. Singh Jayaram Vishakantaiah Jaya K. Meka Vijayan Sivaprahasam Vijayanand Chandrasekaran Rebecca Thombre Vijay Thiruvenkatam Ambresh Mallya Balabhadrapatruni N. Rajasekhar Mariyappan Muruganantham Akshay Datey Hugh Hill Anil Bhardwaj Gopalan Jagadeesh Kalidevapura P. J. Reddy Nigel J. Mason Bhalamurugan Sivaraman 《Molecules (Basel, Switzerland)》2020,25(23)
The building blocks of life, amino acids, are believed to have been synthesized in the extreme conditions that prevail in space, starting from simple molecules containing hydrogen, carbon, oxygen and nitrogen. However, the fate and role of amino acids when they are subjected to similar processes largely remain unexplored. Here we report, for the first time, that shock processed amino acids tend to form complex agglomerate structures. Such structures are formed on timescales of about 2 ms due to impact induced shock heating and subsequent cooling. This discovery suggests that the building blocks of life could have self-assembled not just on Earth but on other planetary bodies as a result of impact events. Our study also provides further experimental evidence for the ‘threads’ observed in meteorites being due to assemblages of (bio)molecules arising from impact-induced shocks. 相似文献
105.
106.
Shaohua Guo Dr. Pan Liu Dr. Yang Sun Kai Zhu Dr. Jin Yi Prof. Mingwei Chen Prof. Masayoshi Ishida Prof. Haoshen Zhou 《Angewandte Chemie (International ed. in English)》2015,54(40):11701-11705
Recently, there has been great interest in developing advanced sodium‐ion batteries for large‐scale application. Most efforts have concentrated on the search for high‐performance electrode materials only in sodium half‐cells. Research on sodium full cells for practical application has encountered many problems, such as insufficient cycles with rapid capacity decay, low safety, and low operating voltage. Herein, we present a layered P2‐Na0.66Ni0.17Co0.17Ti0.66O2, as both an anode (ca. 0.69 V versus Na+/Na) and as a high‐voltage cathode (ca. 3.74 V versus Na+/Na). The full cell based on this bipolar electrode exhibits well‐defined voltage plateaus near 3.10 V, which is the highest average voltage in the symmetric cells. It also shows the longest cycle life (75.9 % capacity retention after 1000 cycles) in all sodium full cells, a usable capacity of 92 mAh g?1, and superior rate capability (65 mAh g?1 at a high rate of 2C). 相似文献
107.
HU Rong TIAN Jinping & YIN Yingwu . College of Chemistry & Environment Protection Engineering Southwest University for Nationalities Chengdu China . TH-UNIS Insight Co. Ltd. Beijing China . Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology Ministry of Education Department of Chemistry Tsinghua University Beijing China 《中国科学B辑(英文版)》2006,49(4):351-356
The formation of peptides and then protein by small abiological molecules clusters such as amino acid is a key stage in the origin of life[1]. More and more ex- perimental results showed that phosphate plays an important role in the formation of biomolecules in prebiotic chemical evolution. The principal reservoirs of biochemical energy are phosphates (such as ATP). The peculiar role of phosphates in contemporary life might suggest its essential role in prebiotic energy conversion, syntheses … 相似文献
108.
Michael Popall Jürgen Kappel Monika Pilz Jochen Schulz Gusty Feyder 《Journal of Sol-Gel Science and Technology》1994,2(1-3):157-160
Inorganic-organic polymers with barrier properties against water vapor, excellent electrical data (3, 2, R
D>1016 cm, E
D up to 400 V/µm) and good adhesion to various substrate materials have been developed. Tailored modifications of these materials provide an excellent protective coating for thin film capacitors. Several mm thick, expensive, encapsulations could be replaced by thin coatings (up to 10 µm). The polymer coating allows the use of thin film chip capacitors in surface-mount technology. As a measure for the efficiency of the coating, the capacitance decrease under controlled humidity has been used. The influence of the material composition, the type of catalyst during sol-gel processing and the curing conditions have been studied. Adhesion and water vapor permeation properties of the polymers and rheological properties of the coating solutions have been investigated. A protective coating is developed, which increases the withstandness of capacitors against humid conditions (90°C, 100% rel. humidity) by a factor of about 30 (compared to uncoated capacitors) and shows no crack formation during thermal cycling. 相似文献
109.
110.
The origin of long homochiral biopolymers in living systems has recently been the focus of intense research. In one particular research line, scientists studied, experimentally and theoretically, chiral amplification obtained during peptide formation by polymerization of amino acid building blocks. It was suggested that processes leading to temporal or spatial separation, and thus, to the growth of homochiral polymers at the expense of their heterochiral counterparts, can explain the chirality observed in larger molecules. We introduce a simple model and stochastic simulation for the polymerization of amino acids and β-sheet formation, showing the crucial effects of the β sheets on the distributions of peptide lengths. When chiral affinities are included, racemic β sheets of alternating homochiral strands lead to the formation of chiral peptides, the isotacticity of which increases with length, consistent with previous experimental results in aqueous solutions. The tendency to form isotactic peptides is shown for both initially racemic and initially nonracemic systems, as well as for closed and open systems. We suggest that these or similar mechanisms may explain the origin of chiroselectivity in prebiotic environments. 相似文献