全文获取类型
收费全文 | 403篇 |
免费 | 20篇 |
国内免费 | 1篇 |
专业分类
424篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 23篇 |
2020年 | 10篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 10篇 |
2016年 | 22篇 |
2015年 | 21篇 |
2014年 | 21篇 |
2013年 | 35篇 |
2012年 | 23篇 |
2011年 | 24篇 |
2010年 | 25篇 |
2009年 | 18篇 |
2008年 | 20篇 |
2007年 | 25篇 |
2006年 | 26篇 |
2005年 | 15篇 |
2004年 | 18篇 |
2003年 | 21篇 |
2002年 | 11篇 |
2001年 | 3篇 |
2000年 | 10篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有424条查询结果,搜索用时 15 毫秒
1.
The protein–nanomaterial interface 总被引:1,自引:1,他引:0
2.
Prashanth Sirigeri Jois 《Biochemical and biophysical research communications》2010,394(4):1036-1041
Bovine BSP5 belongs to the Binder of SPerm (BSP) family. BSP5 plays a role in the bovine sperm capacitation by promoting cholesterol and phospholipid efflux. The variable N-terminal part in the BSP proteins is the uncharacterized region with no known function. Full-length, N-terminal part, and individual fibronectin type II domains of bovine BSP5 were cloned, expressed and purified from Escherichia coli. His-S tagged N-terminal part showed large variation in migration on SDS-PAGE in comparison to other constructs. Using mass spectrometry it was demonstrated that the His-S-N-terminal part has the expected molecular mass (13 kDa). The recombinant N-terminal part was sensitive to E. coli endogenous proteases during purification. Denaturing purification involving boiling lysis of cells was carried out, as the protein was thermostable. The His-S-N-terminal part lacked structure as determined by CD analysis. Bioinformatics analyses confirmed that the N-terminal part of bovine BSP5 is intrinsically disordered. In addition, bioinformatics analysis indicated that rabbit BSP and multiple forms of BSP proteins of bovine and equine species possess partially or completely disordered N-terminus. The conservation of disorder at the N-terminus in BSP members belonging to different species suggests a role in biological process such as sperm capacitation and/or sperm-egg interactions. 相似文献
3.
İlker Zeki Kurtoğlu Kübra Ak Songül Genç 《Zeitschrift fur angewandte Ichthyologie》2021,37(6):809-815
In this study, we investigated the effects of different stocking densities water quality and blood parameters during the transportation of the Siberian sturgeon (Acipenser baerii). Experiments were carried out in high-density polyethylene tank with three different stocking densities (50, 100 and 150 kg/m3) for 20 h. Ammonium nitrogen (NH4-N) and nitrite nitrogen (NO2-N) were measured in the water samples. The erythrocyte, leucocyte, haematocrit (HCT), haemoglobin (Hb), cortisol, and sodium ion (Na+) were measured in blood samples. Ammonium nitrogen and nitrite nitrogen concentrations in the water have increased in parallel with the stocking density depending on the time. In the highest stocking density, the maximum levels of NH4-N and NO2-N at the 16th h reached 2.64 mg/L and 4.74 mg/L, respectively. Erythrocyte, leucocyte, HCT, and Hb values did not differ significantly between the experimental groups (p > .05). The results showed that fish could be transported safely for 20 h in 15℃ water temperature at 50 kg/m3 stocking density; however, stocking density of 100 kg/m3 and over could threaten fish welfare and health as from 16th h. 相似文献
4.
Devina Lobine Bryan Pairyanen Gokhan Zengin Mustafa Abdullah Yılmaz Rayene Ouelbani Souheir Bensari Gunes Ak Hassan H. Abdallah Muhammad Imran Mohamad Fawzi Mahomoodally 《化学与生物多样性》2021,18(4):e2000999
Toddalia asiatica (L.) Lam. is extensively used in traditional medicinal systems by various cultures. Despite its frequent use in traditional medicine, there is still a paucity of scientific information on T. asiatica growing on the tropical island of Mauritius. Therefore, the present study was designed to appraise the pharmacological and phytochemical profile of extracts (methanol, ethyl acetate and water) and essential oil obtained from aerial parts of T. asiatica. Biological investigation involved the evaluation of in vitro antioxidant and enzyme inhibitory potentials. The chemical profile of the EO was determined using gas chromatography coupled to mass spectrometry (GC/MS) analysis, while for the extracts, the total phenolic (TPC) and flavonoid content were quantified as well as their individual phenolic compounds by LC/MS/MS. Quinic acid, fumaric acid, chlorogenic acid, quercitrin and isoquercitrin were the main compounds in the extracts. Highest total phenolic (82.5±0.94 mg gallic acid equivalent (GAE/g)) and flavonoid (43.8±0.31 mg rutin equivalent (RE/g)) content were observed for the methanol extract. The GC/MS analysis has shown the presence of 26 compounds with linalool (30.9 %), linalyl acetate (20.9 %) and β-phellandrene (7.9 %) being most abundant components in the EO. The extracts and EO showed notable antioxidant properties, with the methanol extract proved to be superior source of antioxidant compounds. Noteworthy anti-acetylcholinesterase (AChE) and anti-butyrylcholinesterase (BChE) effects were recorded for the tested samples, while only the methanol and ethyl acetate extracts were active against tyrosinase. With respect to antidiabetic effects, the extracts and EO were potent inhibitors of α-glucosidase, while modest activity was recorded against α-amylase. Docking results showed that linalyl acetate has the highest affinity to interact with the active site of BChE with docking score of −6.25 kcal/mol. The findings amassed herein act as a stimulus for further investigations of this plant as a potential source of bioactive compounds which can be exploited as phyto-therapeutics. 相似文献
5.
Melanie Köllmer Carmen Popescu Prashanth Manda Leon Zhou Richard A. Gemeinhart 《AAPS PharmSciTech》2013,14(4):1333-1340
Pharmaceutical excipients contain reactive groups and impurities due to manufacturing processes that can cause decomposition of active drug compounds. The aim of this investigation was to determine if commercially available oral disintegrating tablet (ODT) platforms induce active pharmaceutical ingredient (API) degradation. Benzocaine was selected as the model API due to known degradation through ester and primary amino groups. Benzocaine was either compressed at a constant pressure, 20 kN, or at pressure necessary to produce a set hardness, i.e., where a series of tablets were produced at different compression forces until an average hardness of approximately 100 N was achieved. Tablets were then stored for 6 months under International Conference on Harmonization recommended conditions, 25°C and 60% relative humidity (RH), or under accelerated conditions, 40°C and 75% RH. Benzocaine degradation was monitored by liquid chromatography–mass spectrometry. Regardless of the ODT platform, no degradation of benzocaine was observed in tablets that were kept for 6 months at 25°C and 60% RH. After storage for 30 days under accelerated conditions, benzocaine degradation was observed in a single platform. Qualitative differences in ODT platform behavior were observed in physical appearance of the tablets after storage under different temperature and humidity conditions. 相似文献
6.
Abdullah Mahboob Serguei Vassiliev Prashanth K. Poddutoori Art van der Est Doug Bruce 《PloS one》2013,8(7)
Photosystem II (PSII) of photosynthesis has the unique ability to photochemically oxidize water. Recently an engineered bacterioferritin photochemical ‘reaction centre’ (BFR-RC) using a zinc chlorin pigment (ZnCe6) in place of its native heme has been shown to photo-oxidize bound manganese ions through a tyrosine residue, thus mimicking two of the key reactions on the electron donor side of PSII. To understand the mechanism of tyrosine oxidation in BFR-RCs, and explore the possibility of water oxidation in such a system we have built an atomic-level model of the BFR-RC using ONIOM methodology. We studied the influence of axial ligands and carboxyl groups on the oxidation potential of ZnCe6 using DFT theory, and finally calculated the shift of the redox potential of ZnCe6 in the BFR-RC protein using the multi-conformational molecular mechanics–Poisson-Boltzmann approach. According to our calculations, the redox potential for the first oxidation of ZnCe6 in the BRF-RC protein is only 0.57 V, too low to oxidize tyrosine. We suggest that the observed tyrosine oxidation in BRF-RC could be driven by the ZnCe6 di-cation. In order to increase the efficiency of tyrosine oxidation, and ultimately oxidize water, the first potential of ZnCe6 would have to attain a value in excess of 0.8 V. We discuss the possibilities for modifying the BFR-RC to achieve this goal. 相似文献
7.
8.
9.
ABSTRACTFT-IR and FT-Raman spectra of 2,2′-bipyridine-3,3′-dicarboxylic acid (B3DA), 2,2′-bipyridine-4,4′-dicarboxylic acid (B4DA) and 2,2′-bipyridine-5,5′-dicarboxylic acid (B5DA) were recorded and analysed. The quantum chemical calculations of the title compounds begin with barrier potentials at different rotation angles around the C–C′ and C–Cα bonds in order to arrive conformation of lowest energy using DFT employing B3LYP functional with 6-311++G(d,p) basis set. This confirmation was further optimised to get the global minimum geometry. The vibrational frequencies along with IR, Raman intensities were computed, the rms error between observed and calculated frequencies were 11.2 cm?1, 10.2 cm?1 and 12.2 cm?1 for B3DA, B4DA, and B5DA. An 87-element modified valence force field is derived by solving the inverse vibrational problem using Wilson’s GF matrix method. This force field is refined using 163 observed fundamentals employing in overlay least-squares technique. The average error between computed and experimental frequencies was found as 12.85 cm?1 using potential energy distribution (PED) and eigenvectors. By using the gauge-independent atomic orbital (GIAO) method calculate the 1H and 13C NMR chemical shifts of the molecules and compared with experimental results. The first-order hyperpolarisability, HOMO and LUMO energies, molecular electrostatic potential (MESP) and natural orbital analysis (NBO) of titled compounds were evaluated using DFT. 相似文献
10.
V. Lakshmi Ranganatha B.R. Vijay Avin Prabhu Thirusangu T. Prashanth B.T. Prabhakar Shaukath Ara Khanum 《Life sciences》2013