全文获取类型
收费全文 | 310篇 |
免费 | 9篇 |
专业分类
化学 | 197篇 |
晶体学 | 1篇 |
力学 | 16篇 |
数学 | 13篇 |
物理学 | 92篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 4篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 11篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 12篇 |
2013年 | 25篇 |
2012年 | 20篇 |
2011年 | 14篇 |
2010年 | 8篇 |
2009年 | 14篇 |
2008年 | 14篇 |
2007年 | 16篇 |
2006年 | 12篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 12篇 |
2002年 | 12篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1963年 | 2篇 |
排序方式: 共有319条查询结果,搜索用时 942 毫秒
151.
Triazole‐Tailored Guanosine Dinucleosides as Biomimetic Ion Channels to Modulate Transmembrane Potential 下载免费PDF全文
Y. Pavan Kumar Rabindra Nath Das Sonu Kumar Ole Mathis Schütte Prof. Dr. Claudia Steinem Prof. Dr. Jyotirmayee Dash 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(11):3023-3028
A “click” ion channel platform has been established by employing a clickable guanosine azide or alkyne with covalent spacers. The resulting guanosine derivatives modulated the traffic of ions across the phospholipid bilayer, exhibiting a variation in conductance spanning three orders of magnitude (pS to nS). Förster resonance energy transfer studies of the dansyl fluorophore with the membrane binding fluorophore Nile red revealed that the dansyl fluorophore is deeply embedded in the phospholipid bilayer. Complementary cytosine can inhibit the conductance of the supramolecular guanosine channels in the phospholipid bilayers. 相似文献
152.
Emal M. Alekozai Pavan K. GhattyVenkataKrishna Edward C. Uberbacher Michael F. Crowley Jeremy C. Smith Xiaolin Cheng 《Cellulose (London, England)》2014,21(2):951-971
The Family 7 cellobiohydrolase (Cel7A) from Trichoderma reesei consists of a carbohydrate-binding module (CBM) joined by a linker to a catalytic domain. Cellulose hydrolysis is limited by the accessibility of Cel7A to crystalline substrates, which is perceived to be primarily mediated by the CBM. Here, the binding of CBM to the cellulose Iβ fiber is characterized by combined Brownian dynamics (BD) and molecular dynamics (MD) simulations. The results confirm that CBM prefers to dock to the hydrophobic than to the hydrophilic fiber faces. Both electrostatic (ES) and van der Waals (VDW) interactions are required for achieving the observed binding preference. The VDW interactions play a more important role in stabilizing the CBM-fiber binding, whereas the ES interactions contribute through the formation of a number of hydrogen bonds between the CBM and the fiber. At long distances, an ES steering effect is also observed that tends to align the CBM in an antiparallel manner relative to the fiber axis. Furthermore, the MD results reveal hindered diffusion of the CBM on all fiber surfaces. The binding of the CBM to the hydrophobic surfaces is found to involve partial dewetting at the CBM-fiber interface coupled with local structural arrangements of the protein. The present simulation results complement and rationalize a large body of previous work and provide detailed insights into the mechanism of the CBM-cellulose fiber interactions. 相似文献
153.
I. Tsakovska A. Gallegos Saliner T. Netzeva M. Pavan A. P. Worth 《SAR and QSAR in environmental research》2013,24(3-4):221-235
The proposed REACH regulation within the European Union (EU) aims to minimise the number of laboratory animals used for human hazard and risk assessment while ensuring adequate protection of human health and the environment. One way to achieve this goal is to develop non-testing methods, such as (quantitative) structure–activity relationships ([Q]SARs), suitable for identifying toxicological hazard from chemical structure and physicochemical properties alone. A database containing data submitted within the EU New Chemicals Notification procedure was compiled by the German Bundesinstitut für Risikobewertung (BfR). On the basis of these data, the BfR built a decision support system (DSS) for the prediction of several toxicological endpoints. For the prediction of eye irritation and corrosion potential, the DSS contains 31 physicochemical exclusion rules evaluated previously by the European Chemicals Bureau (ECB), and 27 inclusion rules that define structural alerts potentially responsible for eye irritation and/or corrosion. This work summarises the results of a study carried out by the ECB to assess the performance of the BfR structural rulebase. The assessment included: (a) evaluation of the structural alerts by using the training set of 1341 substances with experimental data for eye irritation and corrosion; and (b) external validation by using an independent test set of 199 chemicals. Recommendations are made for the further development of the structural rules in order to increase the overall predictivity of the DSS. 相似文献
154.
Marcela Pavan Bagagli Hélia Harumi Sato 《Applied biochemistry and biotechnology》2013,170(5):1057-1065
Transglutaminase catalyzes the cross-linking reaction between a glutamine residue and a free amine residue of proteins leading to the formation of protein aggregates. In this research, the effects of temperature, agitation, and aeration on the production of transglutaminase in a bench reactor by a newly isolated Streptomyces sp. from Brazilian soils were investigated using a factorial experimental design. The parameters evaluated influenced the enzyme production, and the data showed that the best conditions to enhance cell growth were different from those leading to enhanced transglutaminase production. Thus, a temperature and agitation shift strategy was adopted to increase transglutaminase productivity. The temperature and agitation were first set at 34 °C and 350 rpm, respectively, and after 24 h decreasing to 26 °C and 150 rpm until the end of fermentation. The transglutaminase activity obtained was 2.18 U/mL after 42 h of fermentation, which was twice than that obtained using a constant temperature and agitation fermentation strategy. 相似文献
155.
Pavan F. A. Gobbi S. A. Costa T. M. H. Benvenutti E. V. 《Journal of Thermal Analysis and Calorimetry》2002,68(1):199-206
FTIR thermal analysis was used for a hybrid xerogel, anilinepropylsilica, obtained from three different organic precursor
amounts, using HF and NaF as catalysts in the sol–gelprocess. The aniline ring vibrational mode at 1500 cm−1 of attached aniline groups was used to obtain the relative aniline content in the xerogel materials after being submitted
to thermal treatment in the temperature range from 100 to 400°C. This technique allowed to evaluate the thermal stability
of organic phase. The organic coverage on the surface and the fraction of trapped organic groups in closed pores can also
be evaluated.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
156.
Recent experiments have observed bulk superconductivity in doped topological insulators. Here we ask whether vortex Majorana zero modes, previously predicted to occur when s-wave superconductivity is induced on the surface of topological insulators, survive in these doped systems with metallic normal states. Assuming inversion symmetry, we find that they do but only below a critical doping. The critical doping is tied to a topological phase transition of the vortex line, at which it supports gapless excitations along its length. The critical point depends only on the vortex orientation and a suitably defined SU(2) Berry phase of the normal state Fermi surface. By calculating this phase for available band structures we determine that superconducting p-doped Bi(2)Te(3), among others, supports vortex end Majorana modes. Surprisingly, superconductors derived from topologically trivial band structures can support Majorana modes too. 相似文献
157.
Luis Gustavo Saboia Ponte Isadora Carolina Betim Pavan Mariana Camargo Silva Mancini Luiz Guilherme Salvino da Silva Ana Paula Morelli Matheus Brandemarte Severino Rosangela Maria Neves Bezerra Fernando Moreira Simabuco 《Molecules (Basel, Switzerland)》2021,26(7)
Flavonoids represent an important group of bioactive compounds derived from plant-based foods and beverages with known biological activity in cells. From the modulation of inflammation to the inhibition of cell proliferation, flavonoids have been described as important therapeutic adjuvants against several diseases, including diabetes, arteriosclerosis, neurological disorders, and cancer. Cancer is a complex and multifactor disease that has been studied for years however, its prevention is still one of the best known and efficient factors impacting the epidemiology of the disease. In the molecular and cellular context, some of the mechanisms underlying the oncogenesis and the progression of the disease are understood, known as the hallmarks of cancer. In this text, we review important molecular signaling pathways, including inflammation, immunity, redox metabolism, cell growth, autophagy, apoptosis, and cell cycle, and analyze the known mechanisms of action of flavonoids in cancer. The current literature provides enough evidence supporting that flavonoids may be important adjuvants in cancer therapy, highlighting the importance of healthy and balanced diets to prevent the onset and progression of the disease. 相似文献
158.
Vishakha Sharma Krupa Jani Pavan Khosla Erin Butler Donald Siegel Elisa Wurmbach 《Electrophoresis》2019,40(9):1353-1364
This study examined 266 individuals from various populations including African American, East Asian, South Asian, European, and mixed populations to evaluate the ForenSeq? Signature Prep Kit Primer Mix B. Focus was placed on phenotypic and biogeographical ancestry predictions by Illumina's Universal Analysis Software (UAS). These outcomes were compared to those obtained through web‐tools developed at the Erasmus Medical Center (EMC) and available from the Forensic Resource/Reference on Genetics‐knowledge base (FROG‐kb), as well as to eye color predictions by the 8‐plex system. Due to drop‐outs, predictions for eye and hair color by UAS failed for various samples in each run. By including reads below thresholds, predictions could be obtained for all samples through the web‐tools. Eye and hair color predictions for African Americans, East Asians, and South Asians showed no errors. Difficulties however, were noted in intermediate (neither blue nor brown) eye color predictions. These were mitigated by the 8‐plex system through exclusion of one eye color (e.g. “not brown”). Additionally, notable discrepancies were observed in hair color predictions, where some black/dark‐brown haired individuals were predicted to have blond hair. Overall, ancestry predictions were more accurate by FROG‐kb compared to UAS, which did not predict South Asian ancestry, particularly Indian individuals. 相似文献
159.
Aakash D. Nidhankar Goudappagouda Divya S. Mohana Kumari Shailendra Kumar Chaubey Rashmi Nayak Rajesh G. Gonnade G. V. Pavan Kumar Retheesh Krishnan Sukumaran Santhosh Babu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):13179-13185
Room-temperature phosphorescence of metal and heavy atom-free organic molecules has emerged as an area of great potential in recent years. A rational design played a critical role in controlling the molecular ordering to impart efficient intersystem crossing and stabilize the triplet state to achieve room-temperature ultralong phosphorescence. However, in most cases, the strategies to strengthen phosphorescence efficiency have resulted in a reduced lifetime, and the available nearly degenerate singlet-triplet energy levels impart a natural competition between delayed fluorescence and phosphorescence, with the former one having the advantage. Herein, an organic helical assembly supports the exhibition of an ultralong phosphorescence lifetime. In contrary to other molecules, 3,6-phenylmethanone functionalized 9-hexylcarbazole exhibits a remarkable improvement in phosphorescence lifetime (>4.1 s) and quantum yield (11 %) owing to an efficient molecular packing in the crystal state. A right-handed helical molecular array act as a trap and exhibits triplet exciton migration to support the exceptionally longer phosphorescence lifetime. 相似文献
160.
Manoj G. Sanjay H. S. Dinesh P. A. Manoj M. Kumar K. Pavan 《International Applied Mechanics》2022,58(2):236-242
International Applied Mechanics - A wheelchair is perhaps the most important equipment to support patients with disorders in the lower limbs. With the advent of technology, more emphasis is being... 相似文献