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101.
102.
Burkhard Luy Alexander Diener Rolf-Peter Hummel Ernst Sturm Wolf-Rüdiger Ulrich Christian Griesinger 《European journal of biochemistry》2004,271(11):2076-2085
The solution structure of a recombinant mutant [rSP-C (FFI)] of the human surfactant-associated protein C (hSP-C) in a mixture of chloroform and methanol was determined by high-resolution NMR spectroscopy. rSP-C (FFI) contains a helix from Phe5 to the C-terminal Leu34 and is thus longer by two residues than the helix of porcine SP-C (pSP-C), which is reported to start at Val7 in the same solvent. Two sets of resonances at the C-terminus of the peptide were observed, which are explained by low-order oligomerization, probably dimerization of rSP-C (FFI) in its alpha-helical form. The dimerization may be induced by hydrogen bonding of the C-terminal carboxylic groups or by the strictly conserved C-terminal heptapeptide segment with a motif similar to the GxxxG dimerization motif of glycophorin A. Dimerization at the heptapeptide segment would be consistent with findings based on electrospray ionization MS data, chemical cross-linking studies, and CNBr cleavage data. 相似文献
103.
104.
New Karyotypes of Vicia faba L. 总被引:1,自引:1,他引:0
Five new karyotypes of V. faba are presented and the types and positions of the structural changes combined in the construction of these new karyotypes are described. All their chromosomes are easily distinguishable by morphological criteria. These new chromosome complements are presently used to study the inter- and intrachromosomal distribution of induced chromatid aberrations and related problems. 相似文献
105.
106.
Invertases. Primary structures, functions, and roles in plant development and sucrose partitioning. 总被引:28,自引:0,他引:28
A Sturm 《Plant physiology》1999,121(1):1-8
107.
The acid hydrolase alpha-mannosidase, which accumulates in plant vacuoles and probably is involved in the catabolism and turnover of N-linked glycoproteins, is itself a glycoprotein with at least one high-mannose-type and one complex-type N-glycan. The puzzling finding that alpha-mannosidase stably carries its own substrate suggests that the N-glycans have unique topologies, and important functions in protein folding, oligomerization or enzyme activity. As a first step towards the elucidation of this enigma, we purified the N-glycans of jack bean alpha-mannosidase and determined their structures by sugar composition analysis, mass spectrometry and 1H-NMR. The structures of two N-glycans were identified in an approximate ratio of one-to-one: a glucose-containing high-mannose-type glycan (Glc1Man9GlcNAc2) and a small xylose- and fucose-containing complex-type glycan (Xyl1Man1Fuc1GlcNAc2). Isolation and sequencing of glycopeptides strongly suggests that one high-mannose-type and one complex-type glycan are linked to specific glycosylation sites of the large alpha-mannosidase subunit. The high-mannose-type glycan, which is a good substrate of the endoglycosidase (endo-H), can only be removed from the enzyme after denaturation and cleavage of disulfide bonds by a reducing agent, suggesting that this glycan is buried within the folded polypeptide and, thus, protected from its hydrolytic activity. Denaturation and reduction of the native enzyme led to a marked decrease in alpha-mannosidase activity. However, the activity could largely be recovered by renaturation in an appropriate renaturation buffer. In contrast, recovery of alpha-mannosidase activity failed when the high-mannose-type glycan was removed by endo-H prior to renaturation, indicating that this glycan appears to be important for enzyme activity. 相似文献
108.
S. R. Schmolke K. Broeg S. Zander V. Bissinger P. D. Hansen N. Kress B. Herut E. Jantzen G. Krüner A. Sturm W. Körting H. von Westernhagen 《Helgoland Marine Research》1999,53(3-4):257-266
A comprehensive database, containing biological and chemical information, collected in the framework of the bilateral interdisciplinary
MARS project (”biological indicators of natural and man-made changes in marine and coastal waters”) during the years 1995–1997
in the coastal environment of the North Sea, was subjected to a multivariate statistical evaluation. The MARS project was
designated to combine a variety of approaches and to develop a set of methods for the employment of biological indicators
in pollution monitoring and environmental quality assessment. In total, nine ship cruises to four coastal sampling sites were
conducted; 765 fish and 384 mussel samples were analysed for biological and chemical parameters. Additional information on
the chemical background at the sampling sites was derived from sediment samples, collected at each of the four sampling sites.
Based on the available chemical data in sediments and black mussel (Mytilus edulis) a pollution gradient between the selected sites, was established. The chemical body burden of flounder (Platichthys flesus) from these sites, though, did not reflect this gradient equally clear. In contrast, the biological information derived from
measurements in fish samples displayed significant a regional as well as a temporal pattern. A multivariate bioindicator data
matrix was evaluated employing a factor analysis model to identify relations between selected biological indicators, and to
improve the understanding of a regional and temporal component in the parameter response. In a second approach, applying the
k-means algorithm on the data matrix, two significantly different clusters of samples, characterised by the current health
status of the fish, were extracted. Using this classification a temporal, and in the second order, a less pronounced spatial
effect was evident. In particular, during July 1996, a clear sign of deteriorating environmental conditions was extracted
from the biological data matrix.
Received: 20 June 1999 / Received in revised form: 8 November 1999 / Accepted: 8 November 1999 相似文献
109.
Vladimir Bresler Vera Bissinger Avigdor Abelson Halim Dizer Armin Sturm Renate Kratke Lev Fishelson Peter-Diedrich Hansen 《Helgoland Marine Research》1999,53(3-4):219-243
The intensive development of industry and urban structures along the seashores of the world, as well as the immense increase
in marine transportation and other activities, has resulted in the deposition of thousands of new chemicals and organic compounds,
endangering the existence of organisms and ecosystems. The conventional single biomarker methods used in ecological assessment
studies cannot provide an adequate base for environmental health assessment, management and sustainability planning. The present
study uses a set of novel biochemical, physiological, cytogenetic and morphological methods to characterize the state of health
of selected molluscs and fish along the shores of the German North Sea, as well as the Israeli Mediterranean and Red Sea.
The methods include measurement of activity of multixenobiotic resistance-mediated transporter (MXRtr) and the system of active
transport of organic anions (SATOA) as indicators of antixenobiotic defence; glutathione S-transferase (GST) activity as an
indicator of biotransformation of xenobiotics; DNA unwinding as a marker of genotoxicity; micronucleus test for clastogenicity;
levels of phagocytosis for immunotoxicity; cholinesterase (ChE) activity and level of catecholamines as indicators of neurotoxicity;
permeability of external epithelia to anionic hydrophilic probe, intralysosomal accumulation of cationic amphiphilic probe
and activity of non-specific esterases as indicators of cell/tissue viability. Complete histopathological examination was
used for diagnostics of environmental pathology. The obtained data show that the activity of the defensive pumps, MXRtr and
SATOA in the studied organisms was significantly higher in the surface epithelia of molluscs from a polluted site than that
of the same species from control, unpolluted stations, providing clear evidence of response to stress. Enhanced frequency
of DNA lesions (alkaline and acidic DNA unwinding) and micronucleus-containing cells was significantly higher in samples from
polluted sites in comparison to those from the clean sites that exhibited genotoxic and clastogenic activity of the pollutants.
In all the studied molluscs a negative correlation was found between the MXRtr levels of activity and the frequency of micronucleus-containing
hemocytes. The expression of this was in accordance with the level of pollution. The complete histopathological examination
demonstrates significantly higher frequencies of pathological alterations in organs of animals from polluted sites. A strong
negative correlation was found between the frequency of these alterations and MXRtr activity in the same specimens. In addition
to these parameters, a decrease in the viability was noted in molluscs from the polluted sites, but ChE activities remained
similar at most sites. The methods applied in our study unmasked numerous early cryptic responses and negative alterations
of health in populations of marine biota sampled from the polluted sites. This demonstrates that genotoxic, clastogenic and
pathogenic xenobiotics are present and act in the studied sites and this knowledge can provide a reliable base for consideration
for sustainable development.
Received: 2 March 1999 / Received in revised form: 2 August 1999 / Accepted: 3 August 1999 相似文献
110.
A 39-nucleotide leader is trans-spliced onto all trypanosome nuclear mRNAs. The precursor spliced leader RNA was tested for trans-splicing function in vivo by mutating the intron. We report that in Leishmania tarentolae spliced leader RNA 5' modification is influenced by the primary sequence of stem-loop II, the Sm-binding site, and the secondary structure of stem-loop III. The sequence of stem-loop II was found to be important for cap 4 formation and splicing. As in Ascaris, mutagenesis of the bulge nucleotide in stem-loop II was detrimental to trans-splicing. Because restoration of the L. tarentolae stem-loop II structure was not sufficient to restore splicing, this result contrasts the findings in the kinetoplastid Leptomonas, where mutations that restored stem-loop II structure supported splicing. Methylation of the cap 4 structure and splicing was also dependent on both the Sm-binding site and the structure of stem-loop III and was inhibited by incomplete 3' end processing. The critical nature of the L. tarentolae Sm-binding site is consistent with its essential role in the Ascaris spliced leader RNA, whereas in Leptomonas mutation of the Sm-binding site and deletion of stem-loop III did not affect trans-splicing. A pathway for Leishmania spliced leader RNA processing and maturation is proposed. 相似文献