全文获取类型
收费全文 | 1574篇 |
免费 | 109篇 |
国内免费 | 1篇 |
专业分类
1684篇 |
出版年
2023年 | 13篇 |
2022年 | 34篇 |
2021年 | 57篇 |
2020年 | 25篇 |
2019年 | 36篇 |
2018年 | 32篇 |
2017年 | 36篇 |
2016年 | 36篇 |
2015年 | 85篇 |
2014年 | 75篇 |
2013年 | 86篇 |
2012年 | 136篇 |
2011年 | 119篇 |
2010年 | 89篇 |
2009年 | 52篇 |
2008年 | 83篇 |
2007年 | 100篇 |
2006年 | 70篇 |
2005年 | 70篇 |
2004年 | 56篇 |
2003年 | 59篇 |
2002年 | 61篇 |
2001年 | 11篇 |
2000年 | 18篇 |
1999年 | 15篇 |
1998年 | 12篇 |
1997年 | 14篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 8篇 |
1967年 | 4篇 |
1965年 | 3篇 |
1964年 | 3篇 |
排序方式: 共有1684条查询结果,搜索用时 15 毫秒
51.
Sophie S.W. Wang Ching‐Min Huang Yi‐Wei Lee Michael Isaac Chen Szu‐An Chuang Shu‐Hua Chen Ying‐Wei Lu Chun‐Cheng Lin Ka‐Wo Lee Wen‐Hung Hsu Kun‐Pin Wu Yu‐Ju Chen 《Proteomics》2017,17(11)
We reported an integrated platform to explore serum protein variant pattern in cancer and its utility as a new class of biomarker panel for diagnosis. On the model study of serum amyloid A (SAA), we employed nanoprobe‐based affinity mass spectrometry for enrichment, identification and quantitation of SAA variants from serum of 105 gastric cancer patients in comparison with 54 gastritis patients, 54 controls, and 120 patients from other cancer. The result revealed surprisingly heterogeneous and most comprehensive SAA bar code to date, which comprises 24 SAA variants including SAA1‐ and SAA2‐encoded products, polymorphic isoforms, N‐terminal–truncated forms, and three novel SAA oxidized isotypes, in which the variant‐specific peptide sequence were also confirmed by LC‐MS/MS. A diagnostic model was developed for dimension reduction and computational classification of the 24 SAA‐variant bar code, providing good discrimination (AUC = 0.85 ± 3.2E?3) for differentiating gastric cancer group from gastritis and normal groups (sensitivity, 0.76; specificity, 0.81) and was validated with external validation cohort (sensitivity, 0.71; specificity, 0.74). Our platform not only shed light on the occurrence and modification extent of under‐represented serum protein variants in cancer, but also suggested a new concept of diagnostic platform by serum protein variant profile. 相似文献
52.
Serrano-Luna Jde J Cervantes-Sandoval I Calderón J Navarro-García F Tsutsumi V Shibayama M 《Canadian journal of microbiology》2006,52(1):16-23
Acanthamoeba spp. are free-living amoebae that cause amoebic granulomatous encephalitis, skin lesions, and ocular amoebic keratitis in humans. Several authors have suggested that proteases could play a role in the pathogenesis of these diseases. In the present work, we performed a partial biochemical characterization of proteases in crude extracts of Acanthamoeba spp. and in conditioned medium using 7.5% SDS-PAGE copolymerized with 0.1% m/v gelatin as substrate. We distinguished a total of 17 bands with proteolytic activity distributed in two species of Acanthamoeba. The bands ranged from 30 to 188 kDa in A. castellanii and from 34 to 144 kDa in A. polyphaga. Additionally, we showed that the pattern of protease activity differed in the two species of Acanthamoeba when pH was altered. By using protease inhibitors, we found that the proteolytic activities belonged mostly to the serine protease family and secondly to cysteine proteases and that the proteolytic activities from A. castellanii were higher than those in A. polyphaga. Furthermore, aprotinin was found to inhibit crude extract protease activity on Madin-Darby canine kidney (MDCK) monolayers. These data suggest that protease patterns could be more complex than previously reported. 相似文献
53.
Matthew J. Wirick Allison R. Cale Isaac T. Smith Amelia F. Alessi Margaret R. Starostik Liberta Cuko Kyal Lalk Mikayla N. Schmidt Benjamin S. Olson Payton M. Salomon Alexis Santos Axel Schmitter-Snchez Himani Galagali Kevin J. Ranke Payton A. Wolbert Macy L. Knoblock John K. Kim Xantha Karp 《PLoS genetics》2021,17(11)
54.
55.
Isaac Neibaur Maria Gallo Fredy Altpeter 《In vitro cellular & developmental biology. Plant》2008,44(6):480-486
Seashore paspalum (Paspalum vaginatum Swartz) is a salt tolerant, fine textured turfgrass used on golf courses in coastal, tropical, and subtropical regions. A
callus induction and plant regeneration protocol for this commercially important turfgrass species has been developed. Induction
of highly regenerable callus with approximately 400 shoots per cultured immature inflorescence (1 cm in length) was achieved
by culturing 0.2 cm segments on media with 3 mg l−1 3,6-dichloro-2-methoxybenzoic acid (dicamba) and 0.1 or 1.0 mg l−1 benzylaminopurine (BA). A multifactorial experiment demonstrated the combination of 3 mg l−1 dicamba and 1.0 mg l−1 BA for induction of callus resulted in 12 times higher plant regeneration frequency compared to 3 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) alone or ten times higher plant regeneration frequency than the combination of 3 mg
l−1 2,4-D and 1.0 mg l−1 BA. These results are expected to support the development of a genetic transformation protocol for seashore paspalum. 相似文献
56.
57.
Guangyuan Li Isaac N. Hayward Brittany R. Jenkins Heather M. Rothfuss Coleman H. Young Marja T. Nevalainen Aaron Muth Paul R. Thompson Amy M. Navratil Brian D. Cherrington 《PloS one》2016,11(1)
Peptidylarginine deiminases (PADs) post-translationally convert arginine into neutral citrulline residues. Our past work shows that PADs are expressed in the canine and murine mammary glands; however, the mechanisms regulating PAD expression and the function of citrullination in the normal mammary gland are unclear. Therefore, the first objective herein was to investigate regulation of PAD expression in mammary epithelial cells. We first examined PAD levels in CID-9 cells, which were derived from the mammary gland of mid-pregnant mice. PAD3 expression is significantly higher than all other PAD isoforms and mediates protein citrullination in CID-9 cells. We next hypothesized that prolactin regulates PAD3 expression. To test this, CID-9 cells were stimulated with 5 μg/mL of prolactin for 48 hours which significantly increases PAD3 mRNA and protein expression. Use of a JAK2 inhibitor and a dominant negative (DN)-STAT5 adenovirus indicate that prolactin stimulation of PAD3 expression is mediated by the JAK2/STAT5 signaling pathway in CID-9 cells. In addition, the human PAD3 gene promoter is prolactin responsive in CID-9 cells. Our second objective was to investigate the expression and activity of PAD3 in the lactating mouse mammary gland. PAD3 expression in the mammary gland is highest on lactation day 9 and coincident with citrullinated proteins such as histones. Use of the PAD3 specific inhibitor, Cl4-amidine, indicates that PAD3, in part, can citrullinate proteins in L9 mammary glands. Collectively, our results show that upregulation of PAD3 is mediated by prolactin induction of the JAK2/STAT5 signaling pathway, and that PAD3 appears to citrullinate proteins during lactation. 相似文献
58.
Joseph Stabile Daniel Lipus Lorraine Maceda Michele Maltz Nirmal Roy Isaac Wirgin 《Biological invasions》2016,18(9):2517-2529
Phragmites australis is a perennial grass that has invaded wetlands of the northeastern United States over the past century. The Hudson River Estuary and surrounding watersheds are no exception in that populations of P. australis have spread dramatically along its shores and tributaries in the past 40 years. Recent studies have shown that genetically variable populations of P. australis can spread by seed dispersal in addition to clonal mechanisms. It is important to characterize the genetic variation of Hudson River populations as part of a management strategy for this species to determine the mechanisms by which its spreads and colonizes new habitats, particularly those with frequent anthropogenic disturbances. The goals of this study were to quantify levels of genetic variation and structuring in Hudson River populations of P. australis using microsatellite DNA analysis. A total of 354 culms of P. australis were collected from nine locations ranging from Albany, New York to Staten Island, New York in the summers of 2004 (N = 174) and 2011 (N = 180). Microsatellite data from eight loci indicated that the Hudson River Estuary has some of the highest levels of genetic variation of all U. S. Atlantic Coast regions containing P. australis. Gene diversity (Hs) across all loci in the 2004 collection was 0.45 (±0.02) and that of the 2011 collection was 0.47 (±0.07). Patches within sample sites were rarely monoclonal and had multiple genetic phenotypes. Moran’s Identity tests indicated that individuals within a patch were closely related, whereas little genetic relatedness was evident among individuals from sample sites >1 km apart. Spatial structuring was also not evident in autospatial correlation and principle coordinate analyses. These findings suggest that genetic diversity is maintained within stands by sexual reproduction and that seeds are important in dispersal of P. australis across the Hudson River Estuary. Ample habitats are available for establishment of new Phragmites stands due to high levels of anthropogenic disturbance from populations living along the Estuary. Wildlife managers should focus on monitoring habitats that provide seedbed for Phragmites and promote land use practices that prevent soil disturbance and establishment of new stands. 相似文献
59.
Jennifer K. Hellmann Michael G. Sovic H. Lisle Gibbs Adam R. Reddon Constance M. O'Connor Isaac Y. Ligocki Susan Marsh‐Rollo Sigal Balshine Ian M. Hamilton 《Molecular ecology》2016,25(16):4001-4013
In group‐living species, the degree of relatedness among group members often governs the extent of reproductive sharing, cooperation and conflict within a group. Kinship among group members can be shaped by the presence and location of neighbouring groups, as these provide dispersal or mating opportunities that can dilute kinship among current group members. Here, we assessed how within‐group relatedness varies with the density and position of neighbouring social groups in Neolamprologus pulcher, a colonial and group‐living cichlid fish. We used restriction site‐associated DNA sequencing (RADseq) methods to generate thousands of polymorphic SNPs. Relative to microsatellite data, RADseq data provided much tighter confidence intervals around our relatedness estimates. These data allowed us to document novel patterns of relatedness in relation to colony‐level social structure. First, the density of neighbouring groups was negatively correlated with relatedness between subordinates and dominant females within a group, but no such patterns were observed between subordinates and dominant males. Second, subordinates at the colony edge were less related to dominant males in their group than subordinates in the colony centre, suggesting a shorter breeding tenure for dominant males at the colony edge. Finally, subordinates who were closely related to their same‐sex dominant were more likely to reproduce, supporting some restraint models of reproductive skew. Collectively, these results demonstrate that within‐group relatedness is influenced by the broader social context, and variation between groups in the degree of relatedness between dominants and subordinates can be explained by both patterns of reproductive sharing and the nature of the social landscape. 相似文献
60.
Summary Axillary bud expiants from South Pacific (Solomon Islands) taro, Colocasia esculenta var. esculenta cv. Akalomamale (Araceae) cultured on a modified Murashige-Skoog medium containing 1 mg NAA 1–1 and TE formed callus and produced multiple plantlets. Explants died if NAA was present at levels lower than 0.1 mg 1–1. BA was not required and may have been inhibitory. Plantlets developed faster and became larger following transfer to a hormone-free medium two weeks after the start of culture. Fully grown plants were established in a potting mix and are growing well in a greenhouse.Abbreviations BA
benzyladenine
- BM
basal medium
- Ca
Colocasia esculenta var. antiquorum
- Ce
Colocasia esculenta var. esculenta
- Ck
cytokinin(s)
- CW
coconut water
- HSMSM
half strength Murashige Skoog macroelements
- HSMS
half strength Murashige and Skoog medium
- IM
initial medium(ia)
- MS
Murashige and Skoog medium
- NAA
naphthaleneacetic acid
- SM
second medium
- TE
taro corm extract
- UCI
University of California, Irvine 相似文献