全文获取类型
收费全文 | 1452篇 |
免费 | 153篇 |
专业分类
1605篇 |
出版年
2023年 | 12篇 |
2022年 | 20篇 |
2021年 | 32篇 |
2020年 | 22篇 |
2019年 | 23篇 |
2018年 | 25篇 |
2017年 | 32篇 |
2016年 | 58篇 |
2015年 | 89篇 |
2014年 | 107篇 |
2013年 | 103篇 |
2012年 | 136篇 |
2011年 | 108篇 |
2010年 | 76篇 |
2009年 | 55篇 |
2008年 | 96篇 |
2007年 | 91篇 |
2006年 | 77篇 |
2005年 | 61篇 |
2004年 | 58篇 |
2003年 | 44篇 |
2002年 | 58篇 |
2001年 | 16篇 |
2000年 | 7篇 |
1999年 | 14篇 |
1998年 | 12篇 |
1997年 | 17篇 |
1996年 | 13篇 |
1995年 | 17篇 |
1994年 | 17篇 |
1993年 | 13篇 |
1992年 | 15篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 12篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1963年 | 1篇 |
排序方式: 共有1605条查询结果,搜索用时 15 毫秒
21.
Maarten W. Barentsz Hester Wessels Paul J. van Diest Ruud M. Pijnappel Carmen C. van der Pol Arjen J. Witkamp Maurice A. A. J. van den Bosch Helena M. Verkooijen 《PloS one》2014,9(7)
Background
Same-day diagnosis based on histology is increasingly being offered to patients suspected of breast cancer. We evaluated to which extent same-day diagnosis affected diagnostic accuracy and patients'' anxiety levels during the diagnostic phase.Patients and methods
All 759 women referred for same-day evaluation of suspicious breast lesions between November 2011–March 2013 were included. Diagnostic accuracy was assessed by linking all patients to the national pathology database to identify diagnostic discrepancies, in which case slides were reviewed. Patients'' anxiety was measured in 127 patients by the State Trait and Anxiety Inventory on six moments during the diagnostic workup and changes over time (< = 1 week) were analyzed by mixed effect models.Results
Core-needle biopsy was indicated in 374/759 patients (49.3%) and in 205/759 (27%) patients, invasive or in situ cancer was found. Final diagnosis on the same day was provided for 606/759 (79.8%) patients. Overall, 3/759 (0.4%) discordant findings were identified. Anxiety levels decreased significantly over time from 45.2 to 30.0 (P = <0.001). Anxiety levels decreased from 44.4 to 25.9 (P = <0.001) for patients with benign disease, and remained unchanged for patients diagnosed with malignancies (48.6 to 46.7, P = 0.933). Time trends in anxiety were not affected by other patient or disease characteristics like age, education level or (family) history of breast cancer.Conclusion
Same-day histological diagnosis is feasible in the vast majority of patients, without impairing diagnostic accuracy. Patients'' anxiety rapidly decreased in patients with a benign diagnosis and remained constant in patients with malignancy. 相似文献22.
Lskow Florian Galbraith Moira D. Hunt Brian P. V. Perry R. Ian Boersma Maarten Pakhomov Evgeny A. 《Hydrobiologia》2022,849(7):1543-1557
Hydrobiologia - Marine ecosystems on continental shelves face multiple challenges due to anthropogenic disturbances, many of which can change the seawater stoichiometry (C:N:P) and consequently... 相似文献
23.
24.
Proteomics of Protein Secretion by Bacillus subtilis: Separating the “Secrets” of the Secretome 下载免费PDF全文
Harold Tjalsma Haike Antelmann Jan D.H. Jongbloed Peter G. Braun Elise Darmon Ronald Dorenbos Jean-Yves F. Dubois Helga Westers Geeske Zanen Wim J. Quax Oscar P. Kuipers Sierd Bron Michael Hecker Jan Maarten van Dijl 《Microbiological reviews》2004,68(2):207-233
Secretory proteins perform a variety of important “remote-control” functions for bacterial survival in the environment. The availability of complete genome sequences has allowed us to make predictions about the composition of bacterial machinery for protein secretion as well as the extracellular complement of bacterial proteomes. Recently, the power of proteomics was successfully employed to evaluate genome-based models of these so-called secretomes. Progress in this field is well illustrated by the proteomic analysis of protein secretion by the gram-positive bacterium Bacillus subtilis, for which ~90 extracellular proteins were identified. Analysis of these proteins disclosed various “secrets of the secretome,” such as the residence of cytoplasmic and predicted cell envelope proteins in the extracellular proteome. This showed that genome-based predictions reflect only ~50% of the actual composition of the extracellular proteome of B. subtilis. Importantly, proteomics allowed the first verification of the impact of individual secretion machinery components on the total flow of proteins from the cytoplasm to the extracellular environment. In conclusion, proteomics has yielded a variety of novel leads for the analysis of protein traffic in B. subtilis and other gram-positive bacteria. Ultimately, such leads will serve to increase our understanding of virulence factor biogenesis in gram-positive pathogens, which is likely to be of high medical relevance. 相似文献
25.
26.
Subordinates explore but dominants profit: resource competition in high Arctic barnacle goose flocks
Social dominance plays an important role in assessing and obtaining access to patchy or scarce food sources in group-foraging herbivores. We investigated the foraging strategies of individuals with respect to their social position in the group in a flock of nonbreeding, moulting barnacle geese, Branta leucopsis, on high Arctic Spitsbergen. We first determined the dominance rank of individually marked birds. The dominance of an individual was best described by its age and its sex-specific body mass. Mating status explained the large variation in dominance among younger birds, as unpaired yearlings ranked lowest. In an artificially created, competitive situation, subordinate individuals occupied explorative front positions in the flock and were the first to find sites with experimentally enriched vegetation. Nevertheless, they were displaced quickly from these favourable sites by more dominant geese which were able to monopolize them. The enhanced sites were subsequently visited preferentially by individuals that succeeded in feeding there when the exclosures were first opened. Data on walking speed of foraging individuals and nearest-neighbour distances in the group suggest that subordinates try to compensate for a lower energy intake by exploring and by lengthening the foraging bout. Observations of our focal birds during the following breeding season revealed that females that returned to the study area were significantly more dominant in the previous year than those not seen in the area again. Copyright 2001 The Association for the Study of Animal Behaviour. 相似文献
27.
In mitochondria, chloroplasts, and Gram-negative eubacteria, Oxa1p(-like) proteins are critical for the biogenesis of membrane proteins. Here we show that the Gram-positive eubacterium Bacillus subtilis contains two functional Oxa1p orthologues, denoted SpoIIIJ and YqjG. The presence of either SpoIIIJ or YqjG is required for cell viability. Whereas SpoIIIJ is required for sporulation, YqjG is dispensable for this developmental process. The stability of two membrane proteins was found to be mildly affected upon SpoIIIJ limitation in the absence of YqjG. Surprisingly, the topology and stability of other membrane proteins remained unaffected under these conditions. In contrast, SpoIIIJ- and YqjG-limiting conditions resulted in a strong post-translocational defect in the stability of secretory proteins. Together, these data indicate that SpoIIIJ and YqjG of B. subtilis are involved in both membrane protein biogenesis and protein secretion. However, the reduced stability of secretory proteins seems to be the most prominent phenotype of SpoIIIJ/YqjG-depleted B. subtilis cells. In conclusion, our observations show that SpoIIIJ and YqjG have different, but overlapping functions in B. subtilis. Most importantly, it seems that different members of the Oxa1p protein family have acquired at least partly distinct, species-specific, functions that are essential for life. 相似文献
28.
Discovering lactic acid bacteria by genomics 总被引:25,自引:0,他引:25
Klaenhammer T Altermann E Arigoni F Bolotin A Breidt F Broadbent J Cano R Chaillou S Deutscher J Gasson M van de Guchte M Guzzo J Hartke A Hawkins T Hols P Hutkins R Kleerebezem M Kok J Kuipers O Lubbers M Maguin E McKay L Mills D Nauta A Overbeek R Pel H Pridmore D Saier M van Sinderen D Sorokin A Steele J O'Sullivan D de Vos W Weimer B Zagorec M Siezen R 《Antonie van Leeuwenhoek》2002,82(1-4):29-58
This review summarizes a collection of lactic acid bacteria that are now undergoing genomic sequencing and analysis. Summaries are presented on twenty different species, with each overview discussing the organisms fundamental and practical significance, nvironmental habitat, and its role in fermentation, bioprocessing, or probiotics. For those projects where genome sequence data were available by March 2002, summaries include a listing of key statistics and interesting genomic features. These efforts will revolutionize our molecular view of Gram–positive bacteria, as up to 15 genomes from the low GC content lactic acid bacteria are expected to be available in the public domain by the end of 2003. Our collective view of the lactic acid bacteria will be fundamentally changed as we rediscover the relationships and capabilities of these organisms through genomics. 相似文献
29.
Self-organization of vegetation in arid ecosystems 总被引:1,自引:0,他引:1
30.
Susen Werner Bernice C. van Aken Thomas Hulst Maarten A. Frens Jos N. van der Geest Heiko K. Strüder Opher Donchin 《PloS one》2015,10(4)
Previous studies on sensorimotor adaptation revealed no awareness of the nature of the perturbation after adaptation to an abrupt 30° rotation of visual feedback or after adaptation to gradually introduced perturbations. Whether the degree of awareness depends on the magnitude of the perturbation, though, has as yet not been tested. Instead of using questionnaires, as was often done in previous work, the present study used a process dissociation procedure to measure awareness and unawareness. A naïve, implicit group and a group of subjects using explicit strategies adapted to 20°, 40° and 60° cursor rotations in different adaptation blocks that were each followed by determination of awareness and unawareness indices. The awareness index differed between groups and increased from 20° to 60° adaptation. In contrast, there was no group difference for the unawareness index, but it also depended on the size of the rotation. Early adaptation varied between groups and correlated with awareness: The more awareness a participant had developed the more the person adapted in the beginning of the adaptation block. In addition, there was a significant group difference for savings but it did not correlate with awareness. Our findings suggest that awareness depends on perturbation size and that aware and strategic processes are differentially involved during adaptation and savings. Moreover, the use of the process dissociation procedure opens the opportunity to determine awareness and unawareness indices in future sensorimotor adaptation research. 相似文献