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31.
Martyn Kelly Cathy Bennett Michel Coste Cristina Delgado François Delmas Luc Denys Luc Ector Claude Fauville Martial Ferréol Malgorzata Golub Amelie Jarlman Maria Kahlert John Lucey Bernadette Ní Chatháin Isabel Pardo Peter Pfister Joanna Picinska-Faltynowicz Juliette Rosebery Christine Schranz Jochen Schaumburg Herman van Dam Sirje Vilbaste 《Hydrobiologia》2009,621(1):169-182
The European Union (EU)’s Water Framework Directive (WFD) requires that all Member States participate in intercalibration
exercises in order to ensure that ecological status concepts and assessment levels are consistent across the EU. This paper
describes one such exercise, performed by the countries in the Central/Baltic Geographical Intercalibration Group stretching
from Ireland in the west to Estonia in the east and from the southern parts of Scandinavia to the northern regions of Spain
and Italy (but excluding alpine regions, which were intercalibrated separately). In this exercise, methods used to measure
ecological status of rivers using benthic diatoms were compared. Ecological status is estimated as the ratio between the observed
value of a biological element and the value expected in the absence of significant human impact. Approaches to defining the
‘reference sites’, from which these ‘expected’ values were derived, varied from country to country. Minimum criteria were
established as part of the exercise but there was still considerable variation between national reference values, reflecting
typological differences that could not be resolved during the exercise. A simple multimetric index was developed to compare
boundary values using two widely used diatom metrics. Boundary values for high/good status and good/moderate status set by
each participant were converted to their equivalent values of this intercalibration metric using linear regression. Variation
of ±0.05 EQR units around the median value was considered to be acceptable and the exercise provided a means for those Member
States who fell significantly above or below this line to review their approaches and, if necessary, adjust their boundaries.
Handling editor: J. Padisak 相似文献
32.
E. Dworniczek M. Frączek A. Seniuk J. Kassner B. Sobieszczańska J. Adamski U. Ciesielska 《Folia microbiologica》2009,54(6):559-562
The possible presence of biofilms was examined in mucosal specimens of 15 patients, undergoing functional endoscopic sinus surgery or a modified Caldwell-Luc approach for chronic rhinosinusitis (CRS). Biofilms were found in 7 of the 15 patients, positive cultures being obtained in most samples, which supports the role of biofilms as an important factor in the pathogenesis of CRS. 相似文献
33.
The occipital bun is widely considered a Neanderthal feature. Its homology to the ‘hemibun’ observed in some European Upper Palaeolithic anatomically modern humans is a current problem. This study quantitatively evaluates the degree of occipital plane convexity in African and Australian modern human crania to analyse a relationship between this feature and some neurocranial variables. Neanderthal and European Upper Palaeolithic Homo sapiens crania were included in the analysis as well. The results of this study indicated that there is a significant relationship between the degree of occipital plane convexity and the following two features in the examined crania of modern humans: the ratio of the maximum neurocranial height to the maximum width of the vault and the ratio of bregma–lambda chord to bregma–lambda arc. The results also revealed that some H. sapiens crania (modern and fossil) show the Neanderthal shape of the occipital plane and that the neurocranial height and shape of parietal midsagittal profile has an influence on occipital plane convexity in the hominins included in this study. This study suggests that the occurrence of the great convexity of the occipital plane in the Neanderthals and H. sapiens is a “by-product” of the relationship between the same neurocranial features and there is no convincing evidence that the Neanderthal occipital bun and the similar structure in H. sapiens develop during ontogeny in the same way. 相似文献
34.
The new Cu/Hg bimetallic thiocyanato-bridged coordination polymer, [Cu(2-bzpy)Hg(SCN)4]n, has been synthesized and characterized by elemental analysis, magnetic measurements, EPR, and X-ray crystallography. X-ray diffraction analysis reveals that the title complex structure creates 3D network. 相似文献
35.
Daan Waanders Dennis Janssen Mark A. Miller Kenneth A. Mann Nico Verdonschot 《Journal of biomechanics》2009,42(15):2513-2519
The goal of this study was to quantify the micromechanics of the cement–bone interface under tensile fatigue loading using finite element analysis (FEA) and to understand the underlying mechanisms that play a role in the fatigue behavior of this interface. Laboratory cement–bone specimens were subjected to a tensile fatigue load, while local displacements and crack growth on the specimen's surface were monitored. FEA models were created from these specimens based upon micro-computed tomography data. To accurately model interfacial gaps at the interface between the bone and cement, a custom-written erosion algorithm was applied to the bone model. A fatigue load was simulated in the FEA models while monitoring the local displacements and crack propagation. The results showed the FEA models were able to capture the general experimental creep damage behavior and creep stages of the interface. Consistent with the experiments, the majority of the deformation took place at the contact interface. Additionally, the FEA models predicted fatigue crack patterns similar to experimental findings. Experimental surface cracks correlated moderately with FEA surface cracks (r2=0.43), but did not correlate with the simulated crack volume fraction (r2=0.06). Although there was no relationship between experimental surface cracks and experimental creep damage displacement (r2=0.07), there was a strong relationship between the FEA crack volume fraction and the FEA creep damage displacement (r2=0.76). This study shows the additional value of FEA of the cement–bone interface relative to experimental studies and can therefore be used to optimize its mechanical properties. 相似文献
36.
Witold Diakowski Ewa Bielska Marek Langner Aleksander F. Sikorski 《生物化学与生物物理学报:生物膜》2006,1758(1):4-12
We previously showed that erythrocyte and brain spectrins bind phospholipid vesicles and monolayers prepared from phosphatidylethanolamine and phosphatidylserine and their mixtures with phosphatidylcholine (Review: A.F. Sikorski, B. Hanus-Lorenz, A. Jezierski, A. R. Dluzewski, Interaction of membrane skeletal proteins with membrane lipid domain, Acta Biochim. Polon. 47 (2000) 565). Here, we show how changes in the fluidity of the phospholipid monolayer affect spectrin-phospholipid interaction. The presence of up to 10%-20% cholesterol in the PE/PC monolayer facilitates the penetration of the monolayer by both types of spectrin. For monolayers constructed from mixtures of PI/PC and cholesterol, the effect of spectrins was characterised by the presence of two maxima (at 5 and 30% cholesterol) of surface pressure for erythroid spectrin, and a single maximum (at 20% cholesterol) for brain spectrin. The binding assay results indicated a small but easily detectable decrease in the affinity of erythrocyte spectrin for FAT-liposomes prepared from a PE/PC mixture containing cholesterol, and a 2- to 5-fold increase in maximal binding capacity (Bmax) depending on the cholesterol content. On the other hand, the results from experiments with a monolayer constructed from homogenous synthetic phospholipids indicated an increase in Δπ change with the increase in the fatty acyl chain length of the phospholipids used to prepare the monolayer. This was confirmed by the results of a pelleting experiment. Adding spectrins into the subphase of raft-like monolayers constructed from DOPC, SM and cholesterol (1/1/1) induced an increase in surface pressure. The Δπ change values were, however, much smaller than those observed in the case of a natural PE/PC (6/4) monolayer. An increased binding capacity for spectrins of liposomes prepared from a “raft-like” mixture of lipids could also be concluded from the pelleting assay. In conclusion, we suggest that the effect of membrane lipid fluidity on spectrin-phospholipid interactions is not simple but depends on how it is regulated, i.e., by cholesterol content or by the chemical structure of the membrane lipids. 相似文献
37.
Anita Rybka S?awomir Domaga?a Jerzy Mroziński Bohdan Korybut-Daszkiewicz 《Inorganica chimica acta》2006,359(14):4526-4534
Series of NiII and CuII complexes with dianionic [N2O2] ligands were synthesized and characterised applying spectroscopic and X-ray diffraction techniques. The ligands were obtained by 1:2 condensation of ethylene- and propylenediamine with malonic aldehyde derivatives (R2 = H, R1 = H or OCH3). Although the molecular formulae of the complexes are quite similar, the X-ray investigations have proved a significant structural diversity in the solid state. Among others, we found some simple nearly planar molecules stacked in the crystal lattice with electron density of six-membered rings delocalised over the chelate rings as well as some very complex polymeric or nickel acetate bridged trinuclear complexes. The coordination of the nickel ion by surrounding oxygen and nitrogen atoms is square-planar in the simplest case and octahedral in the most complex one. Small topological differences in similar molecules generate completely different crystal structures.From magnetic studies, a small, negative value of J obtained confirms the occurrence of weak antiferromagnetic interactions between the NiII ions in polymeric chain of the propylenediamine dialdehyde substituted derivative. 相似文献
38.
Isolation and primary structures of seven serine proteinase inhibitors from Cyclanthera pedata seeds
Jolanta Kowalska Agnieszka ZabłockaTadeusz Wilusz 《Biochimica et Biophysica Acta (BBA)/General Subjects》2006
Seven new trypsin inhibitors, CyPTI I–VII, were purified from ripe seeds of Cyclanthera pedata by affinity chromatography on immobilized chymotrypsin in the presence of 5 M NaCl followed by preparative native PAGE at pH 8.9. The CyPTIs (Cyclanthera pedata trypsin inhibitors) belong to a well-known squash inhibitor family. They contain 28–30 amino acids and have molecular weights from 3031 to 3367 Da. All the isolated inhibitors strongly inhibit bovine β-trypsin (Ka > 1011 M− 1) and, more weakly, bovine α-chymotrypsin (Ka ≈ 104–106 M− 1). In the presence of 3 M NaCl the association constants of CyPTIs with α-chymotrypsin increased a few hundred fold. Taking advantage of this phenomenon, a high concentration of NaCl was used to isolate the inhibitors by affinity chromatography on immobilized chymotrypsin. It was found that although one of them, CyPTI IV, had split the Asn25–Gly26 peptide bond, its inhibitory activity remained unchanged. The hydrolyzed bond is located downstream of the reactive site. Presumably, the inhibitor is a naturally occurring, double-chain protein arising during posttranslational modifications. 相似文献
39.
Katarzyna Ginda Martyna Bezulska Małgorzata Ziółkiewicz Jarosław Dziadek Jolanta Zakrzewska‐Czerwińska Dagmara Jakimowicz 《Molecular microbiology》2013,87(5):998-1012
Mycobacteria are among the clinically most important pathogens, but still not much is known about the mechanisms of their cell cycle control. Previous studies suggested that the genes encoding ParA and ParB (ATPase and DNA binding protein, respectively, required for active chromosome segregation) may be essential in Mycobacterium tuberculosis. Further research has demonstrated that a Mycobacterium smegmatis parB deletion mutant was viable but exhibited a chromosome segregation defect. Here, we address the question if ParA is required for the growth of M. smegmatis, and which cell cycle processes it affects. Our data show that parA may be deleted, but its deletion leads to growth inhibition and severe disturbances of chromosome segregation and septum positioning. Similar defects are also caused by ParA overproduction. EGFP–ParA localizes as pole‐associated complexes connected with a patch of fluorescence accompanying two ParB complexes. Observed aberrations in the number and positioning of ParB complexes in the parA deletion mutant indicate that ParA is required for the proper localization of the ParB complexes. Furthermore, it is shown that ParA colocalizes and interacts with the polar growth determinant Wag31 (DivIVA homologue). Our results demonstrate that mycobacterial ParA mediates chromosome segregation and co‐ordinates it with cell division and elongation. 相似文献
40.
Adam Huczyński Jacek Rutkowski Izabela Borowicz Joanna Wietrzyk Ewa Maj Bogumil Brzezinski 《Bioorganic & medicinal chemistry letters》2013,23(18):5053-5056
Seven Mannich base derivatives of polyether antibiotic Lasalocid acid (2a–2g) were synthesized and screened for their antiproliferative activity against various human cancer cell lines. A novel chemoselective one-pot synthesis of these Mannich bases was developed. Compounds 2a–2c and 2g with sterically smaller dialkylamine substituent, displayed potent antiproliferative activity (IC50: 3.2–7.3 μM), and demonstrated higher than twofold selectivity for specific type of cancer. The nature of Mannich base substituent on C-2 atom at the aromatic ring may be critical in the search for selectivity towards a particular cancer cell. 相似文献