全文获取类型
收费全文 | 7772篇 |
免费 | 537篇 |
国内免费 | 3篇 |
专业分类
8312篇 |
出版年
2023年 | 49篇 |
2022年 | 95篇 |
2021年 | 185篇 |
2020年 | 110篇 |
2019年 | 134篇 |
2018年 | 180篇 |
2017年 | 194篇 |
2016年 | 273篇 |
2015年 | 430篇 |
2014年 | 440篇 |
2013年 | 525篇 |
2012年 | 632篇 |
2011年 | 536篇 |
2010年 | 359篇 |
2009年 | 321篇 |
2008年 | 405篇 |
2007年 | 448篇 |
2006年 | 388篇 |
2005年 | 359篇 |
2004年 | 343篇 |
2003年 | 318篇 |
2002年 | 297篇 |
2001年 | 88篇 |
2000年 | 53篇 |
1999年 | 91篇 |
1998年 | 83篇 |
1997年 | 63篇 |
1996年 | 51篇 |
1995年 | 60篇 |
1994年 | 57篇 |
1993年 | 57篇 |
1992年 | 49篇 |
1991年 | 52篇 |
1990年 | 57篇 |
1989年 | 34篇 |
1988年 | 36篇 |
1987年 | 16篇 |
1986年 | 30篇 |
1985年 | 28篇 |
1984年 | 29篇 |
1983年 | 19篇 |
1982年 | 28篇 |
1981年 | 25篇 |
1980年 | 14篇 |
1979年 | 17篇 |
1977年 | 12篇 |
1976年 | 19篇 |
1975年 | 13篇 |
1974年 | 21篇 |
1970年 | 16篇 |
排序方式: 共有8312条查询结果,搜索用时 15 毫秒
51.
Oxytocin (OT) in the central nervous system (CNS) influences social cognition and behavior, making it a candidate for treating clinical disorders such as schizophrenia and autism. Intranasal administration has been proposed as a possible route of delivery to the CNS for molecules like OT. While intranasal administration of OT influences social cognition and behavior, it is not well established whether this is an effective means for delivering OT to CNS targets. We administered OT or its vehicle (saline) to 15 primates (Macaca mulatta), using either intranasal spray or a nebulizer, and measured OT concentration changes in the cerebral spinal fluid (CSF) and in blood. All subjects received both delivery methods and both drug conditions. Baseline samples of blood and CSF were taken immediately before drug administration. Blood was collected every 10 minutes after administration for 40 minutes and CSF was collected once post-delivery, at the 40 minutes time point. We found that intranasal administration of exogenous OT increased concentrations in both CSF and plasma compared to saline. Both delivery methods resulted in similar elevations of OT concentration in CSF, while the changes in plasma OT concentration were greater after nasal spray compared to nebulizer. In conclusion our study provides evidence that both nebulizer and nasal spray OT administration can elevate CSF OT levels. 相似文献
52.
53.
54.
55.
Bruno Bērzinś 《Hydrobiologia》1973,41(4):449-451
Ohne Zusammenfassung 相似文献
56.
Design and expression of peptides with antimicrobial activity against Salmonella typhimurium 下载免费PDF全文
Amalia Porta Anna Maria Petrone Silvana Morello Ilaria Granata Francesca Rizzo Domenico Memoli Alessandro Weisz Bruno Maresca 《Cellular microbiology》2017,19(2)
We showed previously that insertion of Synechocystis Δ12‐desaturase in salmonella's membrane alters membrane physical state (MPS), followed by the expression of stress genes causing inability to survive within murine macrophages (MΦ). Recently, we showed that expression of one membrane lipid domain (MLD) of Δ12‐desaturase (ORF200) interferes with salmonella MPS, causing loss of virulence in mice and immunoprotection. Here, we postulate that an α‐antimicrobial peptide (α‐AMP) intercalates within membrane lipids, and depending on its amino acid sequence, it does so within specific key sensors of MLD. In this study, we choose as target for a putative synthetic AMP, PhoP/PhoQ, a sensor that responds to low Mg2+ concentration. We synthesised a modified DNA fragment coding for an amino acid sequence (NUF) similar to that fragment and expressed it in salmonella typhimurium. We showed that the pattern of gene expression controlled by PhoP/PhoQ highlights dysregulation of pathways involving phospholipids biosynthesis, stress proteins and genes coding for antigens. RNA‐Seq of strain expressing ORF200 showed that the pattern of those genes is also altered here. Accumulation of NUF conferred temporary immunoprotection. This represents a powerful procedure to address synthetic α‐AMPs to a specific MLD generating live non‐virulent bacterial strains. 相似文献
57.
Monolayers prepared from myelin conserve all the compositional complexity of the natural membrane when spread at the air-water interface. They show a complex pressure-dependent surface pattern that, on compression, changes from the coexistence of two liquid phases to a viscous fractal phase embedded in a liquid phase. We dissected the role of major myelin protein components, myelin basic protein (MBP), and Folch-Lees proteolipid protein (PLP) as crucial factors determining the structural dynamics of the interface. By analyzing mixtures of a single protein with the myelin lipids we found that MBP and PLP have different surface pressure-dependent behaviors. MBP stabilizes the segregation of two liquid phases at low pressures and becomes excluded from the film under compression, remaining adjacent to the interface. PLP, on the contrary, organizes a fractal-like pattern at all surface pressures when included in a monolayer of the protein-free myelin lipids but it remains mixed in the MBP-induced liquid phase. The resultant surface topography and dynamics is regulated by combined near to equilibrium and out-of-equilibrium effects. PLP appears to act as a surface skeleton for the whole components whereas MBP couples the structuring to surface pressure-dependent extrusion and adsorption processes. 相似文献
58.
Crisan M Yap S Casteilla L Chen CW Corselli M Park TS Andriolo G Sun B Zheng B Zhang L Norotte C Teng PN Traas J Schugar R Deasy BM Badylak S Buhring HJ Giacobino JP Lazzari L Huard J Péault B 《Cell Stem Cell》2008,3(3):301-313
Mesenchymal stem cells (MSCs), the archetypal multipotent progenitor cells derived in cultures of developed organs, are of unknown identity and native distribution. We have prospectively identified perivascular cells, principally pericytes, in multiple human organs including skeletal muscle, pancreas, adipose tissue, and placenta, on CD146, NG2, and PDGF-Rbeta expression and absence of hematopoietic, endothelial, and myogenic cell markers. Perivascular cells purified from skeletal muscle or nonmuscle tissues were myogenic in culture and in vivo. Irrespective of their tissue origin, long-term cultured perivascular cells retained myogenicity; exhibited at the clonal level osteogenic, chondrogenic, and adipogenic potentials; expressed MSC markers; and migrated in a culture model of chemotaxis. Expression of MSC markers was also detected at the surface of native, noncultured perivascular cells. Thus, blood vessel walls harbor a reserve of progenitor cells that may be integral to the origin of the elusive MSCs and other related adult stem cells. 相似文献
59.
Víctor Faundes William G. Newman Laura Bernardini Natalie Canham Jill Clayton-Smith Bruno Dallapiccola Sally J. Davies Michelle K. Demos Amy Goldman Harinder Gill Rachel Horton Bronwyn Kerr Dhavendra Kumar Anna Lehman Shane McKee Jenny Morton Michael J. Parker Julia Rankin Siddharth Banka 《American journal of human genetics》2018,102(1):175-187
60.
Engineering resistance against tomato yellow leaf curl virus (TYLCV) using antisense RNA 总被引:7,自引:0,他引:7
One of the most severe diseases of cultivated tomato worldwide is caused by tomato yellow leaf curl virus (TYLCV), a geminivirus transmitted by the whitefly Bemisia tabaci. Here we describe the application of antisense RNAs to interfere with the disease caused by TYLCV. The target of the antisense RNA is the rare messenger RNA of the Rep protein, encoded by the C1 gene. Transgenic Nicotiana benthamiana plants expressing C1 antisense RNA were obtained and shown to resist infection by TYLCV. Some of the resistant lines are symptomless, and the replication of challenge TYLCV almost completely suppressed. The transgenes mediating resistance were shown to be effective through at least two generations of progeny. 相似文献