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81.
The interaction between lipopolysaccharide (LPS) and an LPS-sensitive serine protease zymogen, factor C, purified from horseshoe crab (Tachypleus tridentatus) hemocytes, was investigated to elucidate the LPS-mediated activation of factor C. The rate of activation of the zymogen factor C was highly dependent on the concentration of LPS and on temperature, and the curve of amount of LPS versus activation showed saturation at 37 degrees C. Moreover, a high-molecular-mass complex formed between factor C and LPS was found in a gel-filtration experiment on a Sepharose 4B column. This complex formation was also confirmed by double diffusion analysis on agarose plates. Triton X-100, which destroys LPS micelles, strongly inhibited the LPS-mediated activation of factor C but not activated factor C. These results indicate that the binding of factor C with LPS is required for its activation and that only LPS-associated factor C generates the active factor C. On the other hand, the LPS-mediated activation of factor C was strongly inhibited by the S-alkylated heavy chain derived from factor C. In contrast, the S-alkylated factor C-light chain did not show any inhibitory effect on the activation of factor C, suggesting that the heavy chain located in the NH2-terminal portion of factor C contains an LPS-binding region. 相似文献
82.
Abstract Extraction of Streptococcus mutans with the detergents HECAMEG and lauroyl sarcosinate preferentially extracted antigen D, previously identified as a low molecular mass wall-associated protein. Western blotting with specific antisera was used to demonstrate that this antigen is the HPr component of the sugar-phosphotransferase transport system. Non-denaturing electrophoresis indicated that HECAMEG selectively extracted only one of the two forms of HPr. It is suggested that this form of HPr may have a specific cell surface location. 相似文献
83.
Syntopic Alouatta seniculus, Ateles chamek and Lagothrix cana (Atelidae) were studied in southwestern Amazonia. Primate populations were first surveyed, and then the party size, diet and vertical spacing were monitored over a 5-month period. Atelids accounted for more than half the survey sightings and Lagothrix was the most abundant. Party sizes recorded for both Alouatta and Lagothrix during monitoring were significantly larger than those recorded during surveys, but no such difference was found for Ateles. Monitored parties were significantly larger in Lagothrix in comparison with either Alouatta or Ateles, as were groups of Ateles in comparison with Alouatta. Mean party size in Ateles decreased progressively during the course of the study, from 8.9 +/- 3.4 in June to 3.9 +/- 2.3 in October. Moraceae was the most important dietary resource for Ateles and Lagothrix, in terms of both feeding records and number of species exploited. There was considerable overlap in the plant taxa exploited, but some notable differences, such as the exclusive use of Hymenaea courbaril (Caesalpinaceae) by Lagothrix and of Euterpe precatoria (Arecaceae) by Ateles. As at other sites in the region, Ateles occupied significantly higher forest strata in comparison with Lagothrix. Despite the preliminary nature of the study, the results indicate a number of ecological differences between species that undoubtedly play an important role in niche separation. 相似文献
84.
M Doi A Asano H Yoshida M Inouguchi K Iwanaga M Sasaki Y Katsuya T Taniguchi D Yamamoto 《The journal of peptide research》2005,66(4):181-189
Bolaform amides were designed from N,N'-bis(carboethoxy-L-valinyl)-diaminoethane (1) by linking t-butyloxycarbonyl-valine through ethylenediamine (EDA) to enable spectroscopic and X-ray diffraction analyses. N,N'-Bis(Boc-L-valinyl)-diaminoethane (2) and N,N'-bis(Boc-D-valinyl)-diaminoethane (3) were composed of L-Val and D-Val, respectively. N-(Boc-L-valinyl)-N'-(Boc-D-valinyl)-diaminoethane (4) was composed of both L-Val and D-Val, and was achiral (meso-peptide). Peptide 5 was a 1:1 mixture of 2 and 3, and was also achiral (racemate). These peptides mediated gelation of corn oil at a concentration of approximately 1%. Within crystals, the peptides formed beta-sheet ribbons, but differences were observed in hydrogen-bonding patterns and side-chain arrangements. These differences were also deduced from temperature dependence of amide protons. Force-field calculations based on the crystal structures indicated that association of beta-sheet ribbons had energy benefits, and it was assumed that molecular aggregation progressed spontaneously. These structural studies indicated the chirality of amino acids affected for the properties of bolaform amides. 相似文献
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A reversed passive latex agglutination (RPLA) assay for detecting Clostridium difficile toxin A is presented. Purified monoclonal antibody (mAb 37B5) was used for latex sensitization. The culture supernatants of 93 strains of C. difficile were tested by RPLA assay and the results compared with those of a commercially available latex agglutination test, PCR and cytotoxin assay with Vero cells. There was agreement between RPLA, cytotoxicity and PCR assays, but 29 strains were positive in the RPLA assay while 35 were positive in the cytotoxicity test and PCR using primer pair NK3-NK2 directed to the nonrepeating portion of the C. difficile toxin A gene. The 6 cytotoxic but RPLA-negative strains were demonstrated to be toxin A-negative/toxin B-positive strains in the PCR assay by using primer pair NK11-NK9 directed to the repeating portion of the C. difficile toxin A gene. There were no cross-reactions with culture supernatants of the other clostridial strains except for two strains of C. sordelli that produced hemorrhagic toxin (which is immunologically related to C. difficile toxin A). 相似文献
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Kawano M Ariyoshi W Iwanaga K Okinaga T Habu M Yoshioka I Tominaga K Nishihara T 《Biochemical and biophysical research communications》2011,(4):1222-580