全文获取类型
收费全文 | 81篇 |
免费 | 5篇 |
专业分类
86篇 |
出版年
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 7篇 |
2014年 | 4篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 7篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 7篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2000年 | 4篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1980年 | 2篇 |
1976年 | 1篇 |
排序方式: 共有86条查询结果,搜索用时 0 毫秒
61.
Margarida Cepa Georgina Correia-da-Silva Elisiário J Tavares da Silva Fernanda MF Roleira Margarida Borges Natércia A Teixeira 《BMC cell biology》2008,9(1):41
Background
Aromatase, the cytochrome P-450 enzyme (CYP19) responsible for estrogen biosynthesis, is an important target for the treatment of estrogen-dependent breast cancer. In fact, the use of synthetic aromatase inhibitors (AI), which induce suppression of estrogen synthesis, has shown to be an effective alternative to the classical tamoxifen for the treatment of postmenopausal patients with ER-positive breast cancer. New AIs obtained, in our laboratory, by modification of the A and D-rings of the natural substrate of aromatase, compounds 3a and 4a, showed previously to efficiently suppress aromatase activity in placental microsomes. In the present study we have investigated the effects of these compounds on cell proliferation, cell cycle progression and induction of cell death using the estrogen-dependent human breast cancer cell line stably transfected with the aromatase gene, MCF-7 aro cells. 相似文献62.
Kihslinger RL Lema SC Nevitt GA 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2006,145(2):145-151
Recent studies suggest that hatchery-reared fish can have smaller brain-to-body size ratios than wild fish. It is unclear, however, whether these differences are due to artificial selection or instead reflect differences in rearing environment during development. Here we explore how rearing conditions influence the development of two forebrain structures, the olfactory bulb and the telencephalon, in juvenile Chinook salmon (Oncorhynchus tshawytscha) spawned from wild-caught adults. First, we compared the sizes of the olfactory bulb and telencephalon between salmon reared in a wild stream vs. a conventional hatchery. We next compared the sizes of forebrain structures between fish reared in an enriched NATURES hatchery and fish reared in a conventional hatchery. All fish were size-matched and from the same genetic cohort. We found that olfactory bulb and telencephalon volumes relative to body size were significantly larger in wild fish compared to hatchery-reared fish. However, we found no differences between fish reared in enriched and conventional hatchery treatments. Our results suggest that significant differences in the volume of the olfactory bulb and telencephalon between hatchery and wild-reared fish can occur within a single generation. 相似文献
63.
Juliana R Martins Francis MF Nunes Alexandre S Cristino Zilá LP Simões Márcia MG Bitondi 《BMC molecular biology》2010,11(1):23
Background
Hexamerins are hemocyanin-derived proteins that have lost the ability to bind copper ions and transport oxygen; instead, they became storage proteins. The current study aimed to broaden our knowledge on the hexamerin genes found in the honey bee genome by exploring their structural characteristics, expression profiles, evolution, and functions in the life cycle of workers, drones and queens. 相似文献64.
Nevitt GA 《The Biological bulletin》2000,198(2):245-253
Antarctic procellariiform seabirds forage over vast stretches of open ocean in search of patchily distributed prey resources. These seabirds are unique in that most species have anatomically well-developed olfactory systems and are thought to have an excellent sense of smell. Results from controlled experiments performed at sea near South Georgia Island in the South Atlantic indicate that different species of procellariiforms are sensitive to a variety of scented compounds associated with their primary prey. These include krill-related odors (pyrazines and trimethylamine) as well as odors more closely associated with phytoplankton (dimethyl sulfide, DMS). Data collected in the context of global climatic regulation suggest that at least one of these odors (DMS) tends to be associated with predictable bathymetry, including upwelling zones and seamounts. Such odor features are not ephemeral but can be present for days or weeks. I suggest that procellariiforms foraging over vast distances may be able to recognize these features reflected in the olfactory landscape over the ocean. On the large scale, such features may aid seabirds in navigation or in locating profitable foraging grounds. Once in a profitable foraging area, procellariiforms may use olfactory cues on a small scale to assist them in locating prey patches. 相似文献
65.
66.
Exploring individual quality: basal metabolic rate and reproductive performance in storm-petrels 总被引:1,自引:0,他引:1
Blackmer Alexis L.; Mauck Robert A.; Ackerman Joshua T.; Huntington Charles E.; Nevitt Gabrielle A.; Williams Joseph B. 《Behavioral ecology》2005,16(5):906-913
Despite evidence that some individuals achieve both superiorreproductive performance and high survivorship, the factorsunderlying variation in individual quality are not well understood.The compensation and increased-intake hypotheses predict thatbasal metabolic rate (BMR) influences reproductive performance;if so, variation in BMR may be related to differences in individualquality. We evaluated whether BMR measured during the incubationperiod provides a proximate explanation for variation in individualquality by measuring the BMRs and reproductive performance ofLeach's storm-petrels (Oceanodroma leucorhoa) breeding on KentIsland, New Brunswick, Canada, during 2000 and 2001. We statisticallycontrolled for internal (body mass, breeding age, sex) and external(year, date, time of day) effects on BMR. We found that maleswith relatively low BMRs hatched their eggs earlier in the seasonand that their chicks' wing growth rates were faster comparedto males with relatively high BMRs. Conversely, BMR was notrelated to egg volume, hatching date, or chick growth rate forfemales or to lifetime (23 years) hatching success for eithersex. Thus, for males but not for females, our results supportthe compensation hypothesis. This hypothesis predicts that animalswith low BMRs will achieve better reproductive performance thananimals with high BMRs because they have lower self-maintenancecosts and therefore can apportion more energy to reproduction.These results provide evidence that intraspecific variationin reproductive performance is related to BMR and suggest thatBMR may influence individual quality in males. 相似文献
67.
Eduardo?M?Del Aguila Marcio?B?Dutra Joab?T?Silva Vania?MF?PaschoalinEmail author 《BMC molecular biology》2005,6(1):9
Background
Preparation of RNA free from DNA is a critical step before performing RT-PCR assay. Total RNA isolated from several sources, including those obtained from Saccharomyces cerevisiae, using routine methodologies are frequently contaminated with DNA, which can give rise to amplification products that mimic the amplicons expected from the RNA target. 相似文献68.
Eduardo?S?SilvaEmail author Gerard?J?Schoone Celia?MF?Gontijo Reginaldo?P?Brazil Raquel?S?Pacheco Henk?DFH?Schallig 《Kinetoplastid biology and disease》2005,4(1):4
Background
The direct agglutination test (DAT) has proved to be a very important sero-diagnostic tool combining high levels of intrinsic validity and ease of performance. Otherwise, fast agglutination screening test (FAST) utilises only one serum dilution making the test very suitable for the screening of large populations. 相似文献69.
Hunter DJ Li J LaValley M Bauer DC Nevitt M DeGroot J Poole R Eyre D Guermazi A Gale D Felson DT 《Arthritis research & therapy》2007,9(5):R108-8
We used data from a longitudinal observation study to determine whether markers of cartilage turnover could serve as predictors of cartilage loss on magnetic resonance imaging (MRI). We conducted a study of data from the Boston Osteoarthritis of the Knee Study (BOKS), a completed natural history study of knee osteoarthritis (OA). All subjects in the study met American College of Rheumatology criteria for knee OA. Baseline and follow-up knee magnetic resonance images were scored for cartilage loss by means of the WORMS (Whole Organ Magnetic Resonance Imaging Score) semiquantitative grading scheme. Within the BOKS population, 80 subjects who experienced cartilage loss and 80 subjects who did not were selected for the purposes of this nested case control study. We assessed the baseline levels of cartilage degradation and synthesis products by means of assays for type I and II cleavage by collagenases (Col2:3/4C(short) or C1,2C), type II cleavage only with Col2:3/4C(longmono) (C2C), type II synthesis (C-propeptide), the C-telopeptide of type II (Col2CTx), aggrecan 846 epitope, and cartilage oligomeric matrix protein (COMP). We performed a logistic regression to examine the relation of levels of each biomarker to the risk of cartilage loss in any knee. All analyses were adjusted for gender, age, and body mass index (BMI); results stratified by gender gave similar results. One hundred thirty-seven patients with symptomatic knee OA were assessed. At baseline, the mean (standard deviation) age was 67 (9) years and 54% were male. Seventy-six percent of the subjects had radiographic tibiofemoral OA (Kellgren & Lawrence grade of greater than or equal to 2) and the remainder had patellofemoral OA. With the exception of COMP, none of the other biomarkers was a statistically significant predictor of cartilage loss. For a 1-unit increase in COMP, the odds of cartilage loss increased 6.09 times (95% confidence interval [CI] 1.34 to 27.67). After the analysis of COMP was adjusted for age, gender, and BMI, the risk for cartilage loss was 6.35 (95% CI 1.36 to 29.65). Among subjects with symptomatic knee OA, a single measurement of increased COMP predicted subsequent cartilage loss on MRI. The other biochemical markers of cartilage synthesis and degradation do not facilitate prediction of cartilage loss. With the exception of COMP, if changes in cartilage turnover in patients with symptomatic knee OA are associated with cartilage loss, they do not appear to affect systemic biomarker levels. 相似文献
70.
Status of complete proteome analysis by mass spectrometry: SILAC labeled yeast as a model system 总被引:4,自引:1,他引:4