全文获取类型
收费全文 | 6934篇 |
免费 | 582篇 |
国内免费 | 39篇 |
专业分类
7555篇 |
出版年
2024年 | 8篇 |
2023年 | 36篇 |
2022年 | 98篇 |
2021年 | 149篇 |
2020年 | 111篇 |
2019年 | 158篇 |
2018年 | 201篇 |
2017年 | 176篇 |
2016年 | 274篇 |
2015年 | 402篇 |
2014年 | 439篇 |
2013年 | 526篇 |
2012年 | 593篇 |
2011年 | 599篇 |
2010年 | 425篇 |
2009年 | 348篇 |
2008年 | 446篇 |
2007年 | 435篇 |
2006年 | 356篇 |
2005年 | 341篇 |
2004年 | 283篇 |
2003年 | 242篇 |
2002年 | 245篇 |
2001年 | 79篇 |
2000年 | 77篇 |
1999年 | 77篇 |
1998年 | 44篇 |
1997年 | 40篇 |
1996年 | 26篇 |
1995年 | 28篇 |
1994年 | 18篇 |
1993年 | 16篇 |
1992年 | 21篇 |
1991年 | 20篇 |
1990年 | 14篇 |
1989年 | 17篇 |
1988年 | 12篇 |
1987年 | 16篇 |
1986年 | 15篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 7篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1975年 | 9篇 |
1974年 | 8篇 |
1972年 | 7篇 |
1971年 | 7篇 |
1970年 | 8篇 |
1968年 | 9篇 |
排序方式: 共有7555条查询结果,搜索用时 15 毫秒
1.
2.
Michael D. Jensen Ji?í Bajnárek Sang Yeoup Lee Soren Nielsen Christina Koutsari 《Journal of lipid research》2009,50(9):1863-1869
The relationship between overnight postabsorptive (fasting) respiratory exchange ratio (RER) and plasma FFA concentrations was addressed using data from three separate protocols, each of which involved careful control of the antecedent diet. Protocol 1 examined the relationship between fasting RER and the previous daytime RER. In Protocol 2 fasting, RER and plasma palmitate concentrations were measured in 29 women and 31 men (body mass index <30 kg·m−2). Protocol 3 analyzed data from Nielsen et al. (Nielsen, S., Z. K. Guo, J. B. Albu, S. Klein, P. C. O''Brien, M. D. Jensen. 2003. Energy expenditure, sex and endogenous fuel availability in humans. J. Clin. Invest. 111: 981-988.) to understand how fasting RER and palmitate concentrations relate within individuals during four consecutive measurements. The results were as follows: 1) Fasting RER was correlated (r = 0.74, P < 0.001) with the previous day''s average RER, and less so with RER variability. 2) Fasting RER was correlated (r = −0.39, P = 0.007) with fasting plasma palmitate concentrations. 3) The pattern of the RER/palmitate relationship was similar within individuals and between individuals; a negative slope was observed significantly more often than a positive slope (χ2 test; P < 0.001). Our findings suggest that, despite a fixed food quotient, the slight departures from energy equilibrium in a controlled General Clinical Research Center environment can effect plasma FFA concentrations. We suggest that including indirect calorimetry as part of FFA metabolism studies may aid in data interpretation. 相似文献
3.
4.
Tyrosinase plays a pivotal role in the synthesis of melanin pigment synthesis on skin utilizing tyrosine as a substrate. Melanin is responsible for the protection against harmful ultraviolet irradiation, which can cause significant pathological conditions, such as skin cancers. However, it can also create esthetic problems when accumulated as hyperpigmented spots. Various skin-whitening ingredients which inhibit tyrosinase activity have been identified. Some of them, especially ones with natural product origins, possess phenolic moiety and have been employed in cosmetic products. Semi-synthetic and synthetic inhibitors have also been developed under inspiration of the natural inhibitors yet some of which have no phenolic groups. In this review, tyrosinase inhibitors with natural, semi-synthetic and synthetic origins are listed up with their structures, activities and characteristics. Further, a recent report on the adverse effect of a natural melanin synthesis inhibitor which was included in skin-whitening cosmetics is also briefly discussed. 相似文献
5.
6.
Il-Young Paik Hwa-Eun Jin Ah-Ram Suh Hee-Tae Roh Sang-Hoon Suh 《Biochemical and biophysical research communications》2009,383(1):103-107
To investigate the effects of hydration status on oxidative DNA damage and exercise performance, 10 subjects ran on a treadmill until exhaustion at 80% VO2max during four different trials [control (C), 3% dehydration (D), 3% dehydration + water (W) or 3% dehydration + sports drink (S)]. Dehydration significantly decreased exercise time to exhaustion (D < C and S). Plasma MDA levels were significantly higher at pre-exercise in D than C. Plasma TAS was significantly lower at pre-exercise in C and S than in D, and was significantly lower in S than D at 60 min of recovery. Dehydration significantly increased oxidative DNA damage during exercise, but fluid replacement with water or sports drink alleviated it equally. These results suggest that (1) dehydration impairs exercise performance and increases DNA damage during exercise to exhaustion; and (2) fluid replacement prolongs exercise endurance and attenuates DNA damage. 相似文献
7.
Scaffolding proteins are involved in the incorporation, anchoring, maintenance, and removal of AMPA receptors (AMPARs) at synapses, either through a direct interaction with AMPARs or via indirect association through auxiliary subunits of transmembrane AMPAR regulatory proteins (TARPs). Synaptic scaffolding molecule (S-SCAM) is a newly characterized member of the scaffolding proteins critical for the regulation and maintenance of AMPAR levels at synapses, and directly binds to TARPs through a PDZ interaction. However, the functional significance of S-SCAM–TARP interaction in the regulation of AMPARs has not been tested. Here we show that overexpression of the C-terminal peptide of TARP-γ2 fused to EGFP abolished the S-SCAM-mediated enhancement of surface GluA2 expression. Conversely, the deletion of the PDZ-5 domain of S-SCAM that binds TARPs greatly attenuated the S-SCAM-induced increase of surface GluA2 expression. In contrast, the deletion of the guanylate kinase domain of S-SCAM did not show a significant effect on the regulation of AMPARs. Together, these results suggest that S-SCAM is regulating AMPARs through TARPs. 相似文献
8.
Distinct effects of climate warming on populations of silver fir (Abies alba) across Europe 下载免费PDF全文
9.
10.
Enzymatic methylation of in vitro synthesized apocytochrome c enhances its transport into mitochondria 总被引:4,自引:0,他引:4