全文获取类型
收费全文 | 1804篇 |
免费 | 119篇 |
出版年
2023年 | 8篇 |
2022年 | 10篇 |
2021年 | 37篇 |
2020年 | 15篇 |
2019年 | 42篇 |
2018年 | 44篇 |
2017年 | 27篇 |
2016年 | 41篇 |
2015年 | 80篇 |
2014年 | 110篇 |
2013年 | 129篇 |
2012年 | 135篇 |
2011年 | 150篇 |
2010年 | 92篇 |
2009年 | 87篇 |
2008年 | 120篇 |
2007年 | 114篇 |
2006年 | 108篇 |
2005年 | 108篇 |
2004年 | 106篇 |
2003年 | 79篇 |
2002年 | 67篇 |
2001年 | 13篇 |
2000年 | 10篇 |
1999年 | 14篇 |
1998年 | 17篇 |
1997年 | 12篇 |
1996年 | 10篇 |
1995年 | 16篇 |
1994年 | 14篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 11篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1972年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有1923条查询结果,搜索用时 296 毫秒
141.
142.
143.
Vilmos Soós Endre Sebestyén Angéla Juhász Marnie E Light Ladislav Kohout Gabriella Szalai Júlia Tandori Johannes Van Staden Ervin Balázs 《BMC plant biology》2010,10(1):236
Background
Smoke released from burning vegetation functions as an important environmental signal promoting the germination of many plant species following a fire. It not only promotes the germination of species from fire-prone habitats, but several species from non-fire-prone areas also respond, including some crops. The germination stimulatory activity can largely be attributed to the presence of a highly active butenolide compound, 3-methyl-2H-furo[2,3-c]pyran-2-one (referred to as karrikin 1 or KAR1), that has previously been isolated from plant-derived smoke. Several hypotheses have arisen regarding the molecular background of smoke and KAR1 action. 相似文献144.
145.
Balogh Z Fóris G Kosztáczky B Paragh G Seres I Zsíros E Kónya G Paragh G 《Peptides》2007,28(10):2081-2083
In human monocytes 100 ng/mL leptin increased both statin-inhibitable free radical and cholesterol production in vitro. In our recent study, we aimed to elucidate the concentration dependence of observed leptin-effect. Following leptin stimulation cholesterol synthesis was measured in the presence of inhibitors to determine affected signal pathways. Leptin at low (10-100 ng/mL) concentrations increased [(14)C]acetate incorporation, whereas at 250 ng/mL and higher concentrations it suppressed cholesterol synthesis. HMG CoA reductase, phosphatidyl-3-kinase (PI3K) and mitogen activated protein kinase (MAPK) were involved in mediating leptin effects at low concentrations, whereas the cholesterol synthesis suppression was abolished by inhibitors of protein kinase C (PKC) and PI3K. 相似文献
146.
Parazzini M Ravazzani P Tognola G Thuróczy G Molnar FB Sacchettini A Ardesi G Mainardi LT 《Bioelectromagnetics》2007,28(2):122-129
In this study, 26 healthy young volunteers were submitted to 900 MHz (2 W) GSM cellular phone exposure and to sham exposure in separate sessions. The study was designed to assess cardiac regulatory mechanism in different autonomic nervous system (ANS) states during exposure to low-intensity EMF. Rest-to-stand protocol was applied to evaluate ANS in quiet condition (rest, vagal prevalence) and after a sympathetic activation (stand). The procedure is conducted twice in a double-blind design: once with a genuine EMF exposure and once with a sham exposure (at least 24 h apart). During each session three-leads electrocardiograms were recorded and RR series extracted off-line. Time domain and frequency domain HRV parameters were calculated in every phase of the protocol and during different exposures. The analysis of the data show there was no statistically significant effect due to EMF exposure both on main (i.e., RR mean) and most of the other HRV parameters. A weak interaction between some HRV parameters (i.e., SDNN, TINN, and triangular index in time domain and LF power in frequency domain analysis) and RF exposure was observed and this effect seems to be gathered around the sympathetic response to stand. 相似文献
147.
Human serum albumin (HSA) is the most prominent protein in plasma, but it is also found in tissues and secretions throughout the body. The three-domain design of HSA provides a variety of binding sites for many ligands, including heme and drugs. HSA has been used as a model multidomain protein to investigate how interdomain interactions affect the global folding/unfolding process. Here, we report on the reversible chemical denaturation of heme-HSA involving three different conformational states (F, N, and B, occurring at pH 4.0, 7.0, and 9.0, respectively) and on the effect of prototypic drugs ibuprofen and warfarin on thermodynamics of the reversible unfolding process. Chaotropic unfolding of heme-HSA in the F, N, and B conformations is governed by different thermodynamic regimes, with the B form showing an entropic stabilization of the structure that compensates an enthalpic destabilization, and the F form easily unfolding under entropic control. Warfarin and ibuprofen binding stabilizes heme-HSA in both N and B states. 相似文献
148.
BACKGROUND: The history of domestication of artichoke and leafy cardoon is not yet fully understood and when and where it occurred remains unknown. Evidence supports the hypothesis that wild cardoon is the wild progenitor of both these crops. Selection for large, non-spiny heads resulted in artichoke and selection for non-spiny, large stalked tender leaves resulted in leafy cardoon. The two crops differ in their reproductive system: artichoke is mostly vegetatively propagated and perennial, while leafy cardoon is seed propagated and mostly grown as an annual plant. Here, new trends in artichoke cultivation are analysed, while the consequences of these tendencies on the conservation of artichoke genetic resources are highlighted. SCOPE: The historical and artistic records, together with recent literature on genetics and biosystematics, are examined with the aim of achieving a better understanding of the present-day knowledge on the domestication of these two crops. CONCLUSIONS: Historical, linguistic and artistic records are consistent with genetic and biosystematic data and indicate that the domestication of artichoke and cardoon diverged at different times and in different places. Apparently, artichoke was domesticated in Roman times, possibly in Sicily, and spread by the Arabs during early Middle Ages. The cardoon was probably domesticated in the western Mediterranean in a later period. 相似文献
149.
Chiappelli F Prolo P Cajulis KD Angeli A Dovio A Perotti P Pautasso M Sartori ML Saba L Mussino S Fraccalini T Fanto F Manfrini E Mocellini C Rosso MG Grasso E 《Bioinformation》2007,2(1):1-4
The emerging domain of epigenetics in molecular medicine finds application for a variety of patient populations. Here, we present fundamental neuroendocrine immune evidence obtained in patients with senile dementia of the Alzheimer's type (sDAT), and discuss the implications of these data from the viewpoint of translational epigenetics of Alzheimer's disease. We followed 18 subjects with mild sDAT treated with acetylcholinesterase inhibitors, and 10 control subjects matched for age in a repeated measure design every six months for 18 months. We monitored psychosocial profile (Mini-Mental State Examination, Functional Assessment Staging, Independence in Activities of Daily Living, Depression, Profile of Moods States) in parallel to immunophenotypic parameters of T cell subpopulations by flow cytometry. Based on change in the mini-mental state score at entry and at 18 months, patients with sDAT were assigned to a "fast progression" (delta greater than 2 points) or to a "slow progression" group (delta less than or equal to 2 points). The change in circulating activated T cells (CD3+Dr+) with time in patients with sDAT was significantly inversely correlated with the change in time in natural killer (NK) cytotoxic activity to cortisol modulation in these patients, which was greater in patients with fast progression, compared to slow progression sDAT. These data indicate underlying neuroendocrine immune processes during progression of sDAT. Our observations suggest that psychoimmune measures such as those we have monitored in this study provide relevant information about the evolving physiological modulation in patients with sDAT during progression of Alzheimer's disease, and point to new or improved translational epigenetic treatment interventions. 相似文献
150.
Prolo P Chiappelli F Angeli A Dovio A Perotti P Pautasso M Sartori ML Saba L Mussino S Fraccalini T Fantó F Mocellini C Rosso MG Grasso E 《Bioinformation》2007,1(9):363-366
Patients with Alzheimer's disease (AD) are characterized by an altered sensitivity to cortisol-mediated modulation of circulating lymphocytes. Longitudinal studies are needed to address the clinical applicability of these abnormalities as prognostic factors. Therefore, we designed a longitudinal study to address the clinical applicability of physiologic modulation of Natural Killer (NK) cell activity as a prognostic factor in AD. NK activity was assessed as baseline measurement and in response to modulation by cortisol at 10(-6)M. To verify the immunophysiological integrity of the NK cell population, we tested augmentation of NK cytotoxicity by human recombinant interleukin (IL)-2 (100 IU/ml) as control. The response to modulation by cortisol or by IL-2 was significantly greater in patients with AD. Based on change in the Mini-Mental State score at entry and at 18 months, patients with AD could be assigned to a "fast progression" (Delta > 2 points) or to a "slow progression" group (Delta 相似文献