全文获取类型
收费全文 | 4796篇 |
免费 | 358篇 |
国内免费 | 1篇 |
出版年
2023年 | 24篇 |
2022年 | 10篇 |
2021年 | 68篇 |
2020年 | 52篇 |
2019年 | 72篇 |
2018年 | 81篇 |
2017年 | 75篇 |
2016年 | 137篇 |
2015年 | 265篇 |
2014年 | 271篇 |
2013年 | 279篇 |
2012年 | 442篇 |
2011年 | 394篇 |
2010年 | 259篇 |
2009年 | 227篇 |
2008年 | 300篇 |
2007年 | 294篇 |
2006年 | 268篇 |
2005年 | 264篇 |
2004年 | 258篇 |
2003年 | 248篇 |
2002年 | 230篇 |
2001年 | 45篇 |
2000年 | 23篇 |
1999年 | 62篇 |
1998年 | 63篇 |
1997年 | 37篇 |
1996年 | 34篇 |
1995年 | 41篇 |
1994年 | 47篇 |
1993年 | 31篇 |
1992年 | 25篇 |
1991年 | 21篇 |
1990年 | 15篇 |
1989年 | 24篇 |
1988年 | 11篇 |
1987年 | 21篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 16篇 |
1983年 | 22篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 16篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1971年 | 3篇 |
排序方式: 共有5155条查询结果,搜索用时 15 毫秒
1.
Coralie Fouquet Jean-Fran?ois Gilles Nicolas Heck Marc Dos Santos Richard Schwartzmann Vidjeacoumary Cannaya Marie-Pierre Morel Robert Stephen Davidson Alain Trembleau Susanne Bolte 《PloS one》2015,10(3)
Resolution, high signal intensity and elevated signal to noise ratio (SNR) are key issues for biologists who aim at studying the localisation of biological structures at the cellular and subcellular levels using confocal microscopy. The resolution required to separate sub-cellular biological structures is often near to the resolving power of the microscope. When optimally used, confocal microscopes may reach resolutions of 180 nm laterally and 500 nm axially, however, axial resolution in depth is often impaired by spherical aberration that may occur due to refractive index mismatches. Spherical aberration results in broadening of the point-spread function (PSF), a decrease in peak signal intensity when imaging in depth and a focal shift that leads to the distortion of the image along the z-axis and thus in a scaling error. In this study, we use the novel mounting medium CFM3 (Citifluor Ltd., UK) with a refractive index of 1.518 to minimize the effects of spherical aberration. This mounting medium is compatible with most common fluorochromes and fluorescent proteins. We compare its performance with established mounting media, harbouring refractive indices below 1.500, by estimating lateral and axial resolution with sub-resolution fluorescent beads. We show furthermore that the use of the high refractive index media renders the tissue transparent and improves considerably the axial resolution and imaging depth in immuno-labelled or fluorescent protein labelled fixed mouse brain tissue. We thus propose to use those novel high refractive index mounting media, whenever optimal axial resolution is required. 相似文献
2.
Gijs Fortrie Susanne Stads Albert-Jan H. Aarnoudse Robert Zietse Michiel G. Betjes 《PloS one》2015,10(3)
Background and Objectives
Acute kidney injury (AKI) necessitating renal replacement therapy (RRT) is associated with high mortality and increased risk for end stage renal disease. However, it is unknown if this applies to patients with a preliminary unremarkable medical history. The purpose of this study was to describe overall and renal survival in critically ill patients with AKI necessitating RRT stratified by the presence of comorbidity.Design, Setting, Participants, and Measurements
A retrospective cohort study was performed, between 1994 and 2010, including all adult critically ill patients with AKI necessitating RRT, stratified by the presence of comorbidity. Logistic regression, survival curve and cox proportional hazards analyses were used to evaluate overall and renal survival. Standardized mortality rate (SMR) analysis was performed to compare long-term survival to the predicted survival in the Dutch population.Results
Of the 1067 patients included only 96(9.0%) had no comorbidity. Hospital mortality was 56.6% versus 43.8% in patients with and without comorbidity, respectively. In those who survived hospitalization 10-year survival was 45.0% and 86.0%, respectively. Adjusted for age, sex and year of treatment, absence of comorbidity was not associated with hospital mortality (OR=0.74, 95%-CI=0.47-1.15), while absence of comorbidity was associated with better long-term survival (adjusted HR=0.28, 95%-CI = 0.14-0.58). Compared to the Dutch population, patients without comorbidity had a similar mortality risk (SMR=1.6, 95%-CI=0.7-3.2), while this was increased in patients with comorbidity (SMR=4.8, 95%-CI=4.1-5.5). Regarding chronic dialysis dependency, 10-year renal survival rates were 76.0% and 92.9% in patients with and without comorbidity, respectively. Absence of comorbidity was associated with better renal survival (adjusted HR=0.24, 95%-CI=0.07-0.76).Conclusions
While hospital mortality remains excessively high, the absence of comorbidity in critically ill patients with RRT-requiring AKI is associated with a relative good long-term prognosis in those who survive hospitalization. 相似文献3.
Susanne Metzger Andrea Erxleben B. Lippert 《Journal of biological inorganic chemistry》1997,2(2):256-264
The analogy between H-bonded nucleobase pairs and their metalated analogues is extended to the hemiprotonated pair of 7,9-dimethylguanine
(7,9-DimeG) and the Watson-Crick and reversed Watson-Crick pair between 7,9-dimethylguaninium (7,9-DimeGH+) and 1-methylcytosine (1-MeC). The crystal structure analyses of two model compounds, trans–[Pt(CH3NH2)2(7,9-DimeG-N1)2](NO3)2 (1) and trans–[Pt(NH3)2(1-MeC-N3)(7, 9-DimeG-N1)](PF6)2· 2.5 H2O (3a) are reported. Pt binding is through N1 of 7,9-DimeG and N3 of 1-MeC. In solution, 3a exists in a mixture with Watson-Crick and reversed Watson-Crick arrangements of the two bases, depending on solvent, concentration
and anions.
Received: 16 October 1996 / Accepted: 27 January 1997 相似文献
4.
5.
Dominique Muschter Nicole Sch?fer Hubert Stangl Rainer H. Straub Susanne Gr?ssel 《PloS one》2015,10(10)
Excessive synovial osteoclastogenesis is a hallmark of rheumatoid arthritis (RA). Concomitantly, local synovial changes comprise neuronal components of the peripheral sympathetic nervous system. Here, we wanted to analyze if collagen-induced arthritis (CIA) alters bone marrow-derived macrophage (BMM) osteoclastogenesis and osteoclast activity, and how sympathetic neurotransmitters participate in this process. Therefore, BMMs from Dark Agouti rats at different CIA stages were differentiated into osteoclasts in vitro and osteoclast number, cathepsin K activity, matrix resorption and apoptosis were analyzed in the presence of acetylcholine (ACh), noradrenaline (NA) vasoactive intestinal peptide (VIP) and assay-dependent, adenylyl cyclase activator NKH477. We observed modulation of neurotransmitter receptor mRNA expression in CIA osteoclasts without affecting protein level. CIA stage-dependently altered marker gene expression associated with osteoclast differentiation and activity without affecting osteoclast number or activity. Neurotransmitter stimulation modulated osteoclast differentiation, apoptosis and activity. VIP, NA and adenylyl cyclase activator NKH477 inhibited cathepsin K activity and osteoclastogenesis (NKH477, 10-6M NA) whereas ACh mostly acted pro-osteoclastogenic. We conclude that CIA alone does not affect metabolism of in vitro generated osteoclasts whereas stimulation with NA, VIP plus specific activation of adenylyl cyclase induced anti-resorptive effects probably mediated via cAMP signaling. Contrary, we suggest pro-osteoclastogenic and pro-resorptive properties of ACh mediated via muscarinic receptors. 相似文献
6.
Phylogenetic signals in thermal traits remain stronger in the tropics if we can believe published physiological data. A reply to McKechnie et al., “Data quality problems undermine analyses of endotherm upper critical temperatures” 下载免费PDF全文
Christian Hof Susanne A. Fritz Roland Prinzinger Markus Pfenninger Katrin Böhning‐Gaese Imran Khaliq 《Journal of Biogeography》2017,44(10):2427-2431
Due to concerns about data quality, McKechnie, Coe, Gerson, and Wolf ( 2016 ) questioned the conclusions of our study (Khaliq et al., 2015 ) published in this journal. Here, we argue that most of the questioned data points are in fact useful for macrophysiological analyses, mostly because the vast majority of data are explicitly reported in the peer‐reviewed physiological literature. Furthermore, we show that our conclusions remain largely robust irrespective of the data inclusion criterion. While we think that constructive debates about the adequate use of primary data in meta‐studies as well as more transparency in data inclusion criteria are indeed useful, we also emphasize that data suitability should be evaluated in the light of the scope and scale of the study in which they are used. We hope that this discussion will not discourage the exchange between disciplines such as biogeography and physiology, as this integration is needed to address some of the most urgent scientific challenges. 相似文献
7.
8.
Markus Draaken Michael Knapp Tracie Pennimpede Johanna M. Schmidt Anne-Karolin Ebert Wolfgang R?sch Raimund Stein Boris Utsch Karin Hirsch Thomas M. Boemers Elisabeth Mangold Stefanie Heilmann Kerstin U. Ludwig Ekkehart Jenetzky Nadine Zwink Susanne Moebus Bernhard G. Herrmann Manuel Mattheisen Markus M. N?then Michael Ludwig Heiko Reutter 《PLoS genetics》2015,11(3)
The bladder exstrophy-epispadias complex (BEEC) represents the severe end of the uro-rectal malformation spectrum, and is thought to result from aberrant embryonic morphogenesis of the cloacal membrane and the urorectal septum. The most common form of BEEC is isolated classic bladder exstrophy (CBE). To identify susceptibility loci for CBE, we performed a genome-wide association study (GWAS) of 110 CBE patients and 1,177 controls of European origin. Here, an association was found with a region of approximately 220kb on chromosome 5q11.1. This region harbors the ISL1 (ISL LIM homeobox 1) gene. Multiple markers in this region showed evidence for association with CBE, including 84 markers with genome-wide significance. We then performed a meta-analysis using data from a previous GWAS by our group of 98 CBE patients and 526 controls of European origin. This meta-analysis also implicated the 5q11.1 locus in CBE risk. A total of 138 markers at this locus reached genome-wide significance in the meta-analysis, and the most significant marker (rs9291768) achieved a P value of 2.13 × 10−12. No other locus in the meta-analysis achieved genome-wide significance. We then performed murine expression analyses to follow up this finding. Here, Isl1 expression was detected in the genital region within the critical time frame for human CBE development. Genital regions with Isl1 expression included the peri-cloacal mesenchyme and the urorectal septum. The present study identified the first genome-wide significant locus for CBE at chromosomal region 5q11.1, and provides strong evidence for the hypothesis that ISL1 is the responsible candidate gene in this region. 相似文献
9.
Drug safety and efficacy are highly variable among patients. Most patients will experience the desired drug effect, but some may suffer from adverse drug reactions or gain no benefit. Pharmacogenetic testing serves as a pre-treatment diagnostic option in situations where failure or adverse events should be avoided at all costs. One such situation is human space flight. On the international space station (ISS), a list of drugs is available to cover typical emergency settings, as well as the long-term treatment of common conditions for the use in self-medicating common ailments developing over a definite period. Here, we scrutinized the list of the 78 drugs permanently available at the ISS (year 2014) to determine the extent to which their metabolism may be affected by genetic polymorphisms, potentially requiring genotype-specific dosing or choice of an alternative drug. The purpose of this analysis was to estimate the potential benefit of pharmacogenetic diagnostics in astronauts to prevent therapy failure or side effects. 相似文献
10.
Frank-Michael Stolz Hans-Peter Pfau Gernot Reipen Susanne Schnittger Karl-Heinz Grzeschik Ingo Hansmann 《Genomics》1991,11(4):948-955
Employing the flow-sorted chromosome 20-specific DNA library LL20NS01, we isolated seven novel unique poly- and monomorphic DNA markers specific to human chromosome 20. Initially, 201 phage clones were analyzed regarding insert size and repetitivity. By testing 14 single- and low-copy number clones for their ability to detect RFLPs, three polymorphisms were revealed by two probes, pFMS22-1.4 [D20S22] and pFMS76 [D20S23]. Seven of twenty probes (35%) were assigned to chromosome 20 using a somatic cell hybrid DNA panel. Five of them were regionally mapped by in situ hybridization. Three DNA markers, pFMS51 [D20S29], pFMS76 [D20S23], and pFMS106 [D20S30], were assigned to 20p11.2-p12, and two markers, pFMS22-1.4 [D20S22] and pFMS135 [D20S31], to 20q12-q13.3. Our new chromosome 20-specific DNA markers should be useful for the molecular characterization of this rather underpopulated human chromosome. 相似文献