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排序方式: 共有141条查询结果,搜索用时 15 毫秒
111.
R M Wadowsky T M Wilson N J Kapp A J West J M Kuchta S J States J N Dowling R B Yee 《Applied and environmental microbiology》1991,57(7):1950-1955
A model was developed to study the multiplication of various Legionella spp. in tap water containing Hartmannella vermiformis. Tap water cultures prepared with the following components were suitable for the multiplication studies: Legionella spp., 10(3) CFU/ml; H. vermiformis, 10(4.4) cysts per ml; and killed Pseudomonas paucimobilis, 10(9) cells per ml. Cocultures were incubated at 37 degrees C for at least 1 week. The following legionellae multiplied in tap water cocultures in each replicate experiment: L. bozemanii (WIGA strain), L. dumoffii (NY-23 and TX-KL strains), L. micdadei (two environmental strains), and L. pneumophila (six environmental strains and one clinical isolate). Growth yield values for these strains were 0.6 to 3.5 log CFU/ml. Legionellae which did not multiply in replicate cocultures included L. anisa (one strain), L. bozemanii (MI-15 strain), L. micdadei (a clinical isolate), L. longbeachae, (one strain), and L. pneumophila (Philadelphia 1 strain). L. gormanii and an environmental isolate of L. pneumophila multiplied in only one of three experiments. None of the legionellae multiplied in tap water containing only killed P. paucimobilis. The mean growth yield (+/- standard deviation) of H. vermiformis in the cocultures was 1.2 +/- 0.1 log units/ml. H. vermiformis supports multiplication of only particular strains of legionellae, some of which are from diverse origins. 相似文献
112.
Replication process of the parvovirus H-1. VIII. Partial denaturation mapping and localization of the replication origin of H-1 replicative-form DNA with electron microscopy. 总被引:7,自引:5,他引:2 下载免费PDF全文
Partial denaturation mapping, restriction endonuclease digestion, and electron microscopy were used to determine which end of the linear duplex replicative-form (RF) DNA molecule contains the origin of RF replication for the parvovirus H-1. This origin was localized within approximately 300 base pairs of the arbitrarily designated right end of the RF DNA, in the EcoRI or HaeII-A fragment. Based on denaturation behavior in formamide, the right end was also found to have a relatively high guanine plus cytosine content, whereas the region adjacent to the left terminus of the RF DNA molecule was adenine plus thymine rich. 相似文献
113.
The activity of gamma-glutamyltranspeptidase (GGTP) was determined in cultured skin fibroblasts initiated from normals and cystinotics. For the most part, fibroblasts cell lines from patients with nephropathic cystinosis had elevated levels of gamma-glutamyltranspeptidase averaging 37.01 ± 5.88 (16 determinations) as compared with levels in cells from normals of 14.53 ± 1.43 (17 determinations) nanomoles p-nitroaniline released/hr/mg protein with glycylglycine as acceptor substrate. Enzymatic activities also were elevated in affected cells when cystine was the receptor substrate. Increased GGTP is not secondary to the abnormal amounts of intracellular free cystine since the depletion of the cystine pool did not affect the elevated transpeptidase levels. Whether the increased transpeptidase is closely related to the genetic basis for cystinosis, however, remains to be elucidated. 相似文献
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Bert O. States 《Dreaming》1998,8(4):223-228
My response to Allan Hobson makes several points. Primarily, I argue that the coherence of any dream cannot be determined by the recall of the dream events alone. Rather, coherence must surely reside in the dreamer's felt involvement in those dream events, and this is virtually impossible to determine from a dream report. Second, in response to Hobson's claim that a purely associative thought process neglects the role of dissociation, I argue that metaphor (analogical thinking in general), in all its forms, consists of a tension between resemblance and dissociation (a shift from one domain to another) and that the function of metaphor is, precisely, to free us from the gravity of received understanding. I suggest ways in which this process operates in all speculation, including art and science. Finally, I discuss the nature of dream orientation in connection with the specimen dream that Hobson provided. 相似文献
116.
The gun cells which develop from germinating cysts in Haptoglossa produce a specialized infection apparatus, the injection tube. Upon eversion this tube fires a missile-like projectile which penetrates the host cuticle and then forms an infective sporidium within the body cavity of the nematode host. The temporal assembly of this complex cell organelle has been determined by serial-section reconstructions of maturing gun cells in a previously undescribed Haptoglossa species. The differentiation of the partially walled inverted injection tube is an unusual example of internal tube growth, in which membrane and wall assembly are temporally separated. There is no evidence that the shape of this inverted tube, which coils around the nucleus until it doubles back on itself, is dictated by the disposition of cytoplasmic microtubules. However, actin-like material was associated with the delimiting membrane of the differentiating tube, particularly in the regions of extension. From these studies it seems likely that the "head and buttress" structures previously depicted as the barbed tip of the "harpoon-like" penetration missile are part of a separate, structurally complex system which we suggest locks the "missile" into position in the invaginated injection tube. From this detailed account of cell architecture, models for the likely mechanism of infection cell firing are discussed, and unresolved questions relating to the cell biology and biochemistry of these complex organelles are highlighted. Copyright 1998 Academic Press. 相似文献
117.
MOTIVATION: Searching a protein sequence database for homologs is a
powerful tool for discovering the structure and function of a sequence. Two
new methods for searching sequence databases have recently been described:
Probabilistic Smith-Waterman (PSW), which is based on Hidden Markov models
for a single sequence using a standard scoring matrix, and a new version of
BLAST (WU-BLAST2), which uses Sum statistics for gapped alignments.
RESULTS: This paper compares and contrasts the effectiveness of these
methods with three older methods (Smith- Waterman: SSEARCH, FASTA and
BLASTP). The analysis indicates that the new methods are useful, and often
offer improved accuracy. These tools are compared using a curated (by Bill
Pearson) version of the annotated portion of PIR 39. Three different
statistical criteria are utilized: equivalence number, minimum errors and
the receiver operating characteristic. For complete-length protein query
sequences from large families, PSW's accuracy is superior to that of the
other methods, but its accuracy is poor when used with partial-length query
sequences. False negatives are twice as common as false positives
irrespective of the search methods if a family-specific threshold score
that minimizes the total number of errors (i.e. the most favorable
threshold score possible) is used. Thus, sensitivity, not selectivity, is
the major problem. Among the analyzed methods using default parameters, the
best accuracy was obtained from SSEARCH and PSW for complete-length
proteins, and the two BLAST programs, plus SSEARCH, for partial-length
proteins.
相似文献
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120.
Data management and preliminary data analysis in the pilot phase of the HUPO Plasma Proteome Project
Adamski M Blackwell T Menon R Martens L Hermjakob H Taylor C Omenn GS States DJ 《Proteomics》2005,5(13):3246-3261
The pilot phase of the HUPO Plasma Proteome Project (PPP) is an international collaboration to catalog the protein composition of human blood plasma and serum by analyzing standardized aliquots of reference serum and plasma specimens using a variety of experimental techniques. Data management for this project included collection, integration, analysis, and dissemination of findings from participating organizations world-wide. Accomplishing this task required a communication and coordination infrastructure specific enough to support meaningful integration of results from all participants, but flexible enough to react to changing requirements and new insights gained during the course of the project and to allow participants with varying informatics capabilities to contribute. Challenges included integrating heterogeneous data, reducing redundant information to minimal identification sets, and data annotation. Our data integration workflow assembles a minimal and representative set of protein identifications, which account for the contributed data. It accommodates incomplete concordance of results from different laboratories, ambiguity and redundancy in contributed identifications, and redundancy in the protein sequence databases. Recommendations of the PPP for future large-scale proteomics endeavors are described. 相似文献