全文获取类型
收费全文 | 413篇 |
免费 | 31篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 17篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 18篇 |
2014年 | 26篇 |
2013年 | 23篇 |
2012年 | 33篇 |
2011年 | 30篇 |
2010年 | 21篇 |
2009年 | 28篇 |
2008年 | 38篇 |
2007年 | 35篇 |
2006年 | 19篇 |
2005年 | 18篇 |
2004年 | 21篇 |
2003年 | 18篇 |
2002年 | 15篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1984年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有444条查询结果,搜索用时 15 毫秒
1.
Porphyridium cultures grown on either nitrate or ammonium as the nitrogen source showed similar patterns of growth and cell wall polysaccharide production. The effect of nitrogen on growth and cell wall polysaccharide production was studied by applying three regimens of supply: batch mode, in which nitrate was supplied at the beginning of the experiment and became depleted at day 6; continual mode, in which nitrate was added daily; and deficient mode, in which the cells were cultured in a nitrate-free medium. Growth was similar in the batch- and continual-mode cultures, whereas it was totally inhibited in the deficient-mode culture. Polysaccharide content (per volume) was highest in the batch-mode culture and lowest in the deficient-mode culture. However, polysaccharide production per cell was similar in the continual- and deficient-mode cultures, the highest value being found in the batch-mode culture. In addition to its effect on polysaccharide content, nitrogen affected the polysaccharide distribution between soluble and bound polysaccharides. In the deficientmode culture, most of the cell wall polysaccharide was dissolved in the medium. 相似文献
2.
Mordechai Manoach Dalia Varon Mordechai Erez 《Molecular and cellular biochemistry》1995,147(1-2):181-185
Ventricular fibrillation (VF) is one of the most life threatening events. Although in humans VF is generally sustained (SVF) requiring artificial defibrillation, in various mammals and in some cases in humans VF terminates by itself, reverting spontaneously into sinus rhythm. Since VF is one of the main causes of sudden death, one of the important clinical problems today is if and how we can transform the fatal SVF into a self limited transient one (TVF).From electrophysiological studies carried out on anaesthetized open chest animals, we have found that TVF requires a high degree of intercellular coupling and synchronization.Cardiac myocytes are electrically coupled with adjacent cells. The intercellular coupling is a focus of low electrical resistance which allows rapid transmission of electrical impulses between cells. Any decrease in intercellular coupling decreases the ability of the heart for self defibrillation. The cell-to-cell coupling decreases with age, ischemia, VF and variations in physiological conditions probably due to an increase in intercellular resistance (Ri), widening in the internexal gaps, decrease in electrotonic space constant () etc. All of these factors are known to be affected by intracellular concentration of free Ca++ ([Ca++]).On the basis of studies carried out on various mammals at different ages, we hypothesized that the ability of the heart to defibrillate depends on the cardiac catecholamine level [CA], during VF. This hypothesis is supported by the facts, known from the literature, that increase in [CA] decreases intracellular free Ca++ concentration, decreases Ri and increases . By these effects, increase in [CA] enhances intercellular coupling and intercellular synchronization, and thereby, according to our hypothesis, leads to spontaneous ventricular defibrillation — TVF.During VF the sympathetic activity is enhanced but in some cases the [CA] does not reach the level needed for TVF. In order to help the heart in its effort to elevate the [CA] during VF, we proposed to treat these cases with drugs which inhibit the reuptake of [CA]. The facts that administration of [CA] reuptake inhibitors, before the induction of VF, and/or intracoronary infusion of adrenaline, during VF, transforms SVF into TVF, emphasized the validity of our hypothesis. 相似文献
3.
4.
Sivan Laviad-Shitrit Rotem Sela Leena Thorat Yehonatan Sharaby Ido Izhaki Bimalendu B. Nath Malka Halpern 《PLoS neglected tropical diseases》2020,14(12)
Vibrio cholerae causes the fatal cholera diarrhea. Chironomids (Diptera; Chironomidae) are abundant in freshwater aquatic habitats and estuaries and are natural reservoirs of V. cholerae. Until now, only the non-O1/O139 serogroups of V. cholerae were identified in chironomids. Here, we explored whether chironomids are natural reservoirs of V. cholerae O1/O139 serogroups, which are associated with cholera endemics and pandemics. All four life stages of chironomids were sampled from two rivers, and a laboratory culture in Pune, India, and from a pond in Israel. In total, we analyzed 223 chironomid samples. The presence of V. cholerae O1/O139 serogroups was verified using molecular tools. Nine chironomid species were identified; of them, Chironomus circumdatus was the most abundant. The presence of V. cholerae serogroup O1 and the cholera toxin genes were detected in samples from all chironomid species. However, serogroup O139 was detected in only two chironomid species. Besides PCR to detect specific genes, a metagenomic analysis that was performed in three selected C. ramosus larvae, identified a list of virulence genes associated with V. cholerae. The findings provide evidence that chironomids are natural reservoirs of toxigenic V. cholerae O1/O139. Chironomid populations and V. cholerae show biannual peak patterns. A similar pattern is found for cholera epidemics in the Bengal Delta region. Thus, we hypothesize that monitoring chironomids in endemic areas of the disease may provide a novel tool for predicting and preventing cholera epidemics. Moreover, serogroup O139 was detected only in two chironomid species that have a restricted distribution in the Indian subcontinent, possibly explaining why the distribution of the O139 serogroup is limited. 相似文献
5.
Olga Shomron Inbar Nevo-Yassaf Tamar Aviad Yakey Yaffe Eitan Erez Zahavi Anna Dukhovny Eran Perlson Ilya Brodsky Adva Yeheskel Metsada Pasmanik-Chor Anna Mironov Galina V. Beznoussenko Alexander A. Mironov Ella H. Sklan George H. Patterson Yoji Yonemura Mara Sannai Christoph Kaether Koret Hirschberg 《The Journal of cell biology》2021,220(6)
COPII and COPI mediate the formation of membrane vesicles translocating in opposite directions within the secretory pathway. Live-cell and electron microscopy revealed a novel mode of function for COPII during cargo export from the ER. COPII is recruited to membranes defining the boundary between the ER and ER exit sites, facilitating selective cargo concentration. Using direct observation of living cells, we monitored cargo selection processes, accumulation, and fission of COPII-free ERES membranes. CRISPR/Cas12a tagging, the RUSH system, and pharmaceutical and genetic perturbations of ER-Golgi transport demonstrated that the COPII coat remains bound to the ER–ERES boundary during protein export. Manipulation of the cargo-binding domain in COPII Sec24B prohibits cargo accumulation in ERES. These findings suggest a role for COPII in selecting and concentrating exported cargo rather than coating Golgi-bound carriers. These findings transform our understanding of coat proteins’ role in ER-to-Golgi transport. 相似文献
6.
Amir Sherman Ravit Eshed Rotem Harel-Beja Galil Tzuri Vitaly Portnoy Shahar Cohen Mor Rubinstein Arthur A. Schaffer Joseph Burger Nurit Katzir Ron Ophir 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2013,126(2):349-358
The availability of sequence information for many plants has opened the way to advanced genetic analysis in many non-model plants. Nevertheless, exploration of genetic variation on a large scale and its use as a tool for the identification of traits of interest are still rare. In this study, we combined a bulk segregation approach with our own-designed microarrays to map the pH locus that influences fruit pH in melon. Using these technologies, we identified a set of markers that are genetically linked to the pH trait. Further analysis using a set of melon cultivars demonstrated that some of these markers are tightly linked to the pH trait throughout our germplasm collection. These results validate the utility of combining microarray technology with a bulk segregation approach in mapping traits of interest in non-model plants. 相似文献
7.
Human housekeeping genes,revisited 总被引:1,自引:0,他引:1
8.
Leeat Keren Ora Zackay Maya Lotan‐Pompan Uri Barenholz Erez Dekel Vered Sasson Guy Aidelberg Anat Bren Danny Zeevi Adina Weinberger Uri Alon Ron Milo Eran Segal 《Molecular systems biology》2013,9(1)
Most genes change expression levels across conditions, but it is unclear which of these changes represents specific regulation and what determines their quantitative degree. Here, we accurately measured activities of ~900 S. cerevisiae and ~1800 E. coli promoters using fluorescent reporters. We show that in both organisms 60–90% of promoters change their expression between conditions by a constant global scaling factor that depends only on the conditions and not on the promoter's identity. Quantifying such global effects allows precise characterization of specific regulation—promoters deviating from the global scale line. These are organized into few functionally related groups that also adhere to scale lines and preserve their relative activities across conditions. Thus, only several scaling factors suffice to accurately describe genome‐wide expression profiles across conditions. We present a parameter‐free passive resource allocation model that quantitatively accounts for the global scaling factors. It suggests that many changes in expression across conditions result from global effects and not specific regulation, and provides means for quantitative interpretation of expression profiles. 相似文献
9.
Rotem Kadir Tamar Harel Barak Markus Yonatan Perez Anna Bakhrat Idan Cohen Michael Volodarsky Miora Feintsein-Linial Elana Chervinski Joel Zlotogora Sara Sivan Ramon Y. Birnbaum Uri Abdu Stavit Shalev Ohad S. Birk 《PLoS genetics》2016,12(3)
Primary microcephaly is a congenital neurodevelopmental disorder of reduced head circumference and brain volume, with fewer neurons in the cortex of the developing brain due to premature transition between symmetrical and asymmetrical cellular division of the neuronal stem cell layer during neurogenesis. We now show through linkage analysis and whole exome sequencing, that a dominant mutation in ALFY, encoding an autophagy scaffold protein, causes human primary microcephaly. We demonstrate the dominant effect of the mutation in drosophila: transgenic flies harboring the human mutant allele display small brain volume, recapitulating the disease phenotype. Moreover, eye-specific expression of human mutant ALFY causes rough eye phenotype. In molecular terms, we demonstrate that normally ALFY attenuates the canonical Wnt signaling pathway via autophagy-dependent removal specifically of aggregates of DVL3 and not of Dvl1 or Dvl2. Thus, autophagic attenuation of Wnt signaling through removal of Dvl3 aggregates by ALFY acts in determining human brain size. 相似文献
10.