全文获取类型
收费全文 | 2279篇 |
免费 | 235篇 |
出版年
2023年 | 29篇 |
2022年 | 41篇 |
2021年 | 101篇 |
2020年 | 54篇 |
2019年 | 62篇 |
2018年 | 107篇 |
2017年 | 68篇 |
2016年 | 103篇 |
2015年 | 175篇 |
2014年 | 172篇 |
2013年 | 165篇 |
2012年 | 194篇 |
2011年 | 192篇 |
2010年 | 115篇 |
2009年 | 97篇 |
2008年 | 109篇 |
2007年 | 103篇 |
2006年 | 77篇 |
2005年 | 58篇 |
2004年 | 78篇 |
2003年 | 73篇 |
2002年 | 56篇 |
2001年 | 20篇 |
2000年 | 15篇 |
1999年 | 14篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 11篇 |
1991年 | 6篇 |
1990年 | 11篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1972年 | 9篇 |
1971年 | 8篇 |
1968年 | 7篇 |
1967年 | 5篇 |
排序方式: 共有2514条查询结果,搜索用时 765 毫秒
181.
Kyle Lapham Mark N. Kvale Jue Lin Sheryl Connell Lisa A. Croen Brad P. Dispensa Lynn Fang Stephanie Hesselson Thomas J. Hoffmann Carlos Iribarren Eric Jorgenson Lawrence H. Kushi Dana Ludwig Tetsuya Matsuguchi William B. McGuire Sunita Miles Charles P. Quesenberry Jr. Sarah Rowell Marianne Sadler Lori C. Sakoda David Smethurst Carol P. Somkin Stephen K. Van Den Eeden Lawrence Walter Rachel A. Whitmer Pui-Yan Kwok Neil Risch Catherine Schaefer Elizabeth H. Blackburn 《Genetics》2015,200(4):1061-1072
The Kaiser Permanente Research Program on Genes, Environment, and Health (RPGEH) Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort includes DNA specimens extracted from saliva samples of 110,266 individuals. Because of its relationship to aging, telomere length measurement was considered an important biomarker to develop on these subjects. To assay relative telomere length (TL) on this large cohort over a short time period, we created a novel high throughput robotic system for TL analysis and informatics. Samples were run in triplicate, along with control samples, in a randomized design. As part of quality control, we determined the within-sample variability and employed thresholds for the elimination of outlying measurements. Of 106,902 samples assayed, 105,539 (98.7%) passed all quality control (QC) measures. As expected, TL in general showed a decline with age and a sex difference. While telomeres showed a negative correlation with age up to 75 years, in those older than 75 years, age positively correlated with longer telomeres, indicative of an association of longer telomeres with more years of survival in those older than 75. Furthermore, while females in general had longer telomeres than males, this difference was significant only for those older than age 50. An additional novel finding was that the variance of TL between individuals increased with age. This study establishes reliable assay and analysis methodologies for measurement of TL in large, population-based human studies. The GERA cohort represents the largest currently available such resource, linked to comprehensive electronic health and genotype data for analysis. 相似文献
182.
183.
184.
Isolation and Genetic Characterization of Toxoplasma gondii from Black Bears (Ursus americanus), Bobcats (Lynx rufus), and Feral Cats (Felis catus) from Pennsylvania
下载免费PDF全文
![点击此处可从《The Journal of eukaryotic microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jitender P. Dubey Shiv K. Verma Rafael Calero‐Bernal Ana B. Cassinelli Oliver C. H. Kwok Kyle Van Why Chunlei Su Jan G. Humphreys 《The Journal of eukaryotic microbiology》2015,62(3):410-415
Toxoplasma gondii infects virtually all warm‐blooded hosts worldwide. Recently, attention has been focused on the genetic diversity of the parasite to explain its pathogenicity in different hosts. It has been hypothesized that interaction between feral and domestic cycles of T. gondii may increase unusual genotypes in domestic cats and facilitate transmission of potentially more pathogenic genotypes to humans, domestic animals, and wildlife. In the present study, we tested black bear (Ursus americanus), bobcat (Lynx rufus), and feral cat (Felis catus) from the state of Pennsylvania for T. gondii infection. Antibodies to T. gondii were found in 32 (84.2%) of 38 bears, both bobcats, and 2 of 3 feral cats tested by the modified agglutination test (cut off titer 1:25). Hearts from seropositive animals were bioassayed in mice, and viable T. gondii was isolated from 3 of 32 bears, 2 of 2 bobcats, and 2 of 3 feral cats. DNA isolated from culture‐derived tachyzoites of these isolates was characterized using multilocus PCR‐RFLP markers. Three genotypes were revealed, including ToxoDB PCR‐RFLP genotype #1 or #3 (Type II, 1 isolate), #5 (Type 12, 3 isolates), and #216 (3 isolates), adding to the evidence of genetic diversity of T. gondii in wildlife in Pennsylvania. Pathogenicity of 3 T. gondii isolates (all #216, 1 from bear, and 2 from feral cat) was determined in outbred Swiss Webster mice; all three were virulent causing 100% mortality. Results indicated that highly mouse pathogenic strains of T. gondii are circulating in wildlife, and these strains may pose risk to infect human through consuming of game meat. 相似文献
185.
186.
187.
Efficient salt removal in a continuously operated upflow microbial desalination cell with an air cathode 总被引:1,自引:0,他引:1
Microbial desalination cells (MDCs) hold great promise for drinking water production because of potential energy savings during the desalination process. In this study, we developed a continuously operated MDC - upflow microbial desalination cell (UMDC) for the purpose of salt removal. During the 4-month operation, the UMDC constantly removed salts and generated bio-electricity. At a hydraulic retention time (HRT) of 4 days (salt solution) and current production of ∼62 mA, the UMDC was able to remove more than 99% of NaCl from the salt solution that had an initial salt concentration of 30 g total dissolved solids (TDS)/L. In addition, the TDS removal rate was 7.50 g TDS L−1 d−1 (salt solution volume) or 5.25 g TDS L−1 d−1 (wastewater volume), and the desalinated water met the drinking water standard, in terms of TDS concentration. A high charge transfer efficiency of 98.6% or 81% was achieved at HRT 1 or 4 d. The UMDC produced a maximum power density of 30.8 W/m3. The phenomena of bipolar electrodialysis and proton transport in the UMDC were discussed. These results demonstrated the potential of the UMDC as either a sole desalination process or a pre-desalination reactor for downstream desalination processes. 相似文献
188.
Kyle A. Cutting Keith A. Hobson Jay J. Rotella Jeffrey M. Warren Susan E. Wainwright‐de la Cruz John Y. Takekawa 《Journal of avian biology》2011,42(6):505-513
Lesser scaup Aythya affinis populations have declined throughout the North American continent for the last three decades. It has been hypothesized that the loss and degradation of staging habitats has resulted in reduced female body condition on the breeding grounds and a concomitant decline in productivity. We explored the importance of body (endogenous) reserves obtained prior to arrival on the breeding ground in egg protein formation in southwestern Montana during 2006–2008 using stable‐carbon (δ13C) and nitrogen (δ15N) isotope analyses of scaup egg components, female tissue, and local prey items. From arrival on the breeding grounds through the egg‐laying period, δ15N values of scaup red blood cells decreased while δ13C values became less variable; a pattern consistent with endogenous tissues equilibrating with local (freshwater) dietary sources. In 2006 and 2008, isotopic values for egg albumen and yolk protein indicated that most (>90%) protein used to produce these components was obtained on the breeding grounds. However, in 2007, a year with an exceptionally warm and dry spring, endogenous reserves contributed on average 41% of yolk and 29% of albumen. Results from this study suggest that female scaup can meet the protein needs of egg production largely from local dietary food sources. This highlights the importance of providing high‐quality breeding habitats for scaup. Whether this pattern holds in areas with similar breeding season lengths but longer migration routes, such as those found in the western boreal forest, should be investigated. 相似文献
189.
The hippocampus is critical to remembering the flow of events in distinct experiences and, in doing so, bridges temporal gaps between discontiguous events. Here, we report a robust hippocampal representation of sequence memories, highlighted by "time cells" that encode successive moments during an empty temporal gap between the key events, while also encoding location and ongoing behavior. Furthermore, just as most place cells "remap" when a salient spatial cue is altered, most time cells form qualitatively different representations ("retime") when the main temporal parameter is altered. Hippocampal neurons also differentially encode the key events and disambiguate different event sequences to compose unique, temporally organized representations of specific experiences. These findings suggest that hippocampal neural ensembles segment temporally organized memories much the same as they represent locations of important events in spatially defined environments. 相似文献
190.
Neitz RJ Konradi AW Sham HL Zmolek W Wong K Qin A Lorentzen C Nakamura D Quinn KP Sauer JM Powell K Ruslim L Chereau D Ren Z Anderson J Bard F Yednock TA Griswold-Prenner I 《Bioorganic & medicinal chemistry letters》2011,21(12):3726-3729
In this Letter, we describe the evolution of selective JNK3 inhibitors from 1, that routinely exhibit >10-fold selectivity over JNK1 and >1000-fold selectivity over related MAPKs. Strong SAR was found for substitution of the naphthalene ring, as well as for inhibitors adopting different central scaffolds. Significant potency gains were appreciated by inverting the polarity of the thione of the parent triazolothione 1, resulting in potent compounds with attractive pharmacokinetic profiles. 相似文献