全文获取类型
收费全文 | 5076篇 |
免费 | 385篇 |
国内免费 | 2篇 |
专业分类
5463篇 |
出版年
2023年 | 22篇 |
2022年 | 37篇 |
2021年 | 69篇 |
2020年 | 47篇 |
2019年 | 70篇 |
2018年 | 81篇 |
2017年 | 65篇 |
2016年 | 110篇 |
2015年 | 203篇 |
2014年 | 221篇 |
2013年 | 274篇 |
2012年 | 379篇 |
2011年 | 420篇 |
2010年 | 264篇 |
2009年 | 234篇 |
2008年 | 335篇 |
2007年 | 318篇 |
2006年 | 274篇 |
2005年 | 288篇 |
2004年 | 265篇 |
2003年 | 266篇 |
2002年 | 259篇 |
2001年 | 78篇 |
2000年 | 73篇 |
1999年 | 77篇 |
1998年 | 56篇 |
1997年 | 35篇 |
1996年 | 36篇 |
1995年 | 44篇 |
1994年 | 41篇 |
1993年 | 30篇 |
1992年 | 35篇 |
1991年 | 40篇 |
1990年 | 35篇 |
1989年 | 25篇 |
1988年 | 32篇 |
1987年 | 31篇 |
1986年 | 15篇 |
1985年 | 17篇 |
1984年 | 27篇 |
1983年 | 31篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1980年 | 17篇 |
1979年 | 12篇 |
1978年 | 15篇 |
1977年 | 15篇 |
1976年 | 12篇 |
1975年 | 8篇 |
1973年 | 8篇 |
排序方式: 共有5463条查询结果,搜索用时 7 毫秒
1.
2.
Daren Lee Seth Ruffins Queenie Ng Nikhil Sane Steve Anderson Arthur Toga 《BMC bioinformatics》2010,11(1):608
Background
Digital atlases provide a common semantic and spatial coordinate system that can be leveraged to compare, contrast, and correlate data from disparate sources. As the quality and amount of biological data continues to advance and grow, searching, referencing, and comparing this data with a researcher's own data is essential. However, the integration process is cumbersome and time-consuming due to misaligned data, implicitly defined associations, and incompatible data sources. This work addressing these challenges by providing a unified and adaptable environment to accelerate the workflow to gather, align, and analyze the data. 相似文献3.
4.
Sam Mavandadi Steve Feng Frank Yu Stoyan Dimitrov Karin Nielsen-Saines William R. Prescott Aydogan Ozcan 《PloS one》2012,7(10)
We propose a methodology for digitally fusing diagnostic decisions made by multiple medical experts in order to improve accuracy of diagnosis. Toward this goal, we report an experimental study involving nine experts, where each one was given more than 8,000 digital microscopic images of individual human red blood cells and asked to identify malaria infected cells. The results of this experiment reveal that even highly trained medical experts are not always self-consistent in their diagnostic decisions and that there exists a fair level of disagreement among experts, even for binary decisions (i.e., infected vs. uninfected). To tackle this general medical diagnosis problem, we propose a probabilistic algorithm to fuse the decisions made by trained medical experts to robustly achieve higher levels of accuracy when compared to individual experts making such decisions. By modelling the decisions of experts as a three component mixture model and solving for the underlying parameters using the Expectation Maximisation algorithm, we demonstrate the efficacy of our approach which significantly improves the overall diagnostic accuracy of malaria infected cells. Additionally, we present a mathematical framework for performing ‘slide-level’ diagnosis by using individual ‘cell-level’ diagnosis data, shedding more light on the statistical rules that should govern the routine practice in examination of e.g., thin blood smear samples. This framework could be generalized for various other tele-pathology needs, and can be used by trained experts within an efficient tele-medicine platform. 相似文献
5.
Frank H. Gleason Steve K. Schmidt Agostina V. Marano 《Extremophiles : life under extreme conditions》2010,14(5):417-425
Zoosporic true fungi are thought to be ubiquitous in many ecosystems, especially in cool, moist soils and freshwater habitats
which are rich in organic matter. However, some of the habitats where these fungi are found may periodically experience extreme
conditions, such as soils in extremely dry, hot and cold climates, acidic and alkaline soils, polluted rivers, anaerobic soil
and water, saline soil and water, periglacial soils, oligotrophic soils, tree canopies and hydrothermal vents. It is clear
that many ecotypes of zoosporic true fungi have indeed adapted to extreme or stressful environmental conditions. This conclusion
is supported by studies in both the field and in the laboratory. Therefore, in our opinion, at least some true zoosporic fungi
can be considered to be extremophiles. 相似文献
6.
Steve E. Bellan 《PloS one》2010,5(4)
Nearly all mathematical models of vector-borne diseases have assumed that vectors die at constant rates. However, recent empirical research suggests that mosquito mortality rates are frequently age dependent. This work develops a simple mathematical model to assess how relaxing the classical assumption of constant mortality affects the predicted effectiveness of anti-vectorial interventions. The effectiveness of mosquito control when mosquitoes die at age dependent rates was also compared across different extrinsic incubation periods. Compared to a more realistic age dependent model, constant mortality models overestimated the sensitivity of disease transmission to interventions that reduce mosquito survival. Interventions that reduce mosquito survival were also found to be slightly less effective when implemented in systems with shorter EIPs. Future transmission models that examine anti-vectorial interventions should incorporate realistic age dependent mortality rates. 相似文献
7.
8.
Human papillomavirus deoxyribonucleic acid was detected in prostate tissue from patients with benign prostatic hyperplasia or prostatic carcinoma. Radiolabelled genomic probes, specific for the sexually transmitted human papillomavirus types 16 and 18, were used to detect viral genomic sequences in prostate DNA samples analyzed by the Southern blot technique. Viral sequences were identified in DNA from 7 of 16 prostate samples including both hyperplastic and carcinoma tissues and including tissues obtained by transurethral resection or suprapubic prostatectomy. These data indicate that the prostate gland can be infected with human papillomavirus and imply that the prostate may act as a reservoir for the sexual transmission of papillomavirus via seminal fluid. The detection of both episomal and integrated viral DNA sequences in prostate tissue may have important implications for the etiology of prostate disease. 相似文献
9.
Do male hoots betray parasite loads in Tawny Owls? 总被引:1,自引:0,他引:1
Bird song structure may honestly reveal the health and vigour of individual males to potential mates and competitors. If this is the case then song may reflect the level of parasitic infections in males. We initially examined the relationship between blood parasite infections and the time taken to respond by 22 male Tawny Owls to a broadcast hoot. We then examined the call structure (total length and frequency) in relation to parasite infection, an index of owl condition and an index of food abundance. Owls with higher parasite loads responded more slowly to an intruder, although this relationship was not significant once condition and vole abundance were controlled for. We found no relationship between call length and any of the measured variables. However, the high frequency and the range of frequencies used in calls decreased with increasing parasite load. Thus, there was the potential for individuals to assess male parasite load from the speed of response and the structure of the call. Experimental tests of these relationships are now required. 相似文献
10.
Janet L. Taylor Jonathan D. G. Jones Steve Sandler Gunhild M. Mueller John Bedbrook Pamela Dunsmuir 《Molecular & general genetics : MGG》1987,210(3):572-577
Summary The Serratia marcescens chiA gene encodes a secreted chitinase activity which contributes to the fungal growth inhibition exhibited by this bacterium. The coding region from the chiA gene was fused to the promoter and 3 polyadenylation region of the Agrobacterium nopaline synthase gene. Site-directed mutagenesis of specific nucleotides surrounding the initiating AUG of the coding sequence of this chimeric gene resulted in up to an eight-fold increase in the amount of chitinase protein detected in transformed plant tissue. Analysis of the chiA mRNA indicated that these nucleotides also affected mRNA levels. At least 50% of the chitinase protein produced in transformed tobacco cells was the same molecular weight as the S. marcescen secreted protein. 相似文献