全文获取类型
收费全文 | 5218篇 |
免费 | 406篇 |
国内免费 | 5篇 |
专业分类
5629篇 |
出版年
2023年 | 21篇 |
2022年 | 59篇 |
2021年 | 96篇 |
2020年 | 71篇 |
2019年 | 70篇 |
2018年 | 131篇 |
2017年 | 109篇 |
2016年 | 164篇 |
2015年 | 293篇 |
2014年 | 320篇 |
2013年 | 348篇 |
2012年 | 449篇 |
2011年 | 405篇 |
2010年 | 269篇 |
2009年 | 231篇 |
2008年 | 329篇 |
2007年 | 290篇 |
2006年 | 273篇 |
2005年 | 246篇 |
2004年 | 252篇 |
2003年 | 242篇 |
2002年 | 160篇 |
2001年 | 110篇 |
2000年 | 101篇 |
1999年 | 90篇 |
1998年 | 29篇 |
1997年 | 35篇 |
1996年 | 36篇 |
1995年 | 25篇 |
1994年 | 17篇 |
1993年 | 16篇 |
1992年 | 37篇 |
1991年 | 26篇 |
1990年 | 18篇 |
1989年 | 16篇 |
1988年 | 22篇 |
1987年 | 19篇 |
1986年 | 19篇 |
1985年 | 14篇 |
1984年 | 15篇 |
1983年 | 15篇 |
1982年 | 11篇 |
1981年 | 14篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 7篇 |
1975年 | 12篇 |
1974年 | 9篇 |
1971年 | 6篇 |
排序方式: 共有5629条查询结果,搜索用时 15 毫秒
951.
Jung-Youn Han Meeyul Hwang Sung-Yong Hwa Jin-Kyu Park Mi-Ran Ki Il-Hwa Hong Ah-Young Kim Eun-Mi Lee Eun-Joo Lee Chang-Woo Min Kyung-Ku Kang Myeong-Mi Lee Soo-Eun Sung Kyu-Shik Jeong 《Molecular and cellular biochemistry》2014,391(1-2):175-182
ENA-actimineral resource A (ENA-A) is an alkaline mineral water and has a few biological activities such as antioxidant activity. The aim of this study was to examine the effects of ENA-A on lifespan in mice using senescence marker protein-30 knockout mice. The present study had groups of 18-week-old mice (n = 24), 26-week-old mice (n = 12), and 46-week-old mice (n = 20). Each differently aged mice group was divided into three subgroups: a control group, a 5 % ENA-A-treated group, and a 10 % ENA-A-treated group. Mice in the 18-week-old group were treated with vitamin C drinking water 1.5 g/L. However, the mice in the 26-week-old and 46-week-old groups were not treated with vitamin C. The experiments were done for 18 weeks. All vitamin C-treated mice were alive at week 18 (100 % survival rate). In the non-vitamin C group, the 10 % ENA-A-treated mice were alive at week 18. The control and 5 % ENA-A-treated mice died by week 15. As expected, vitamin C was not detected in the non-vitamin C-treated group. However, vitamin C levels were increased in an ENA-A dose-dependent manner in the vitamin C-treated group. In the TUNEL assay, a number of positive hepatocytes significantly decreased in an ENA-A dose-dependent manner. Periodic acid Schiff positive hepatocytes were significantly increased in an ENA-A dose-dependent manner. In addition, the expression level of CuZnSOD was increased by the ENA-A treatment. These data suggest that the intake of ENA-A has a critical role in the anti-aging mechanism and could be applied toward the lifespans of humans. 相似文献
952.
953.
Hong IH Ji H Hwa SY Jeong WI Jeong DH Do SH Kim JM Ki MR Park JK Goo MJ Hwang OK Hong KS Han JY Chung HY Jeong KS 《Marine biotechnology (New York, N.Y.)》2011,13(3):462-473
ENA Actimineral Resource A (ENA-A) is alkaline water that is composed of refined edible cuttlefish bone and two different species of seaweed, Phymatolithon calcareum and Lithothamnion corallioides. In the present study, ENA-A was investigated as an antioxidant to protect against CCl(4)-induced oxidative stress and hepatotoxicity in rats. Liver injury was induced by either subacute or chronic CCl(4) administration, and the rats had free access to tap water mixed with 0% (control group) or 10% (v/v) ENA-A for 5 or 8?weeks. The results of histological examination and measurement of antioxidant activity showed that the reactive oxygen species production, lipid peroxidation, induction of CYP2E1 were decreased and the antioxidant activity, including glutathione and catalase production, was increased in the ENA-A groups as compared with the control group. On 2-DE gel analysis of the proteomes, 13 differentially expressed proteins were obtained in the ENA-A groups as compared with the control group. Antioxidant proteins, including glutathione S-transferase, kelch-like ECH-associated protein 1, and peroxiredoxin 1, were increased with hepatocyte nuclear factor 3-beta and serum albumin precursor, and kininogen precursor decreased more in the ENA-A groups than compared to the control group. In conclusion, our results suggest that ENA-A does indeed have some protective capabilities against CCl(4)-induced liver injury through its antioxidant function. 相似文献
954.
Homolasonolide A and 10-desmethyllasonolide A are biologically less active than lasonolide A. The ethyl ester analogue of lasonolide A exhibited higher activity than the parent compound in some biological test. 相似文献
955.
Kim JH Lee ER Jeon K Choi HY Lim H Kim SJ Chae HJ Park SH Kim S Seo YR Kim JH Cho SG 《Biochimica et biophysica acta》2012,1823(4):876-888
Bax Inhibitor-1 (BI-1) is an evolutionally conserved apoptotic suppressor and belongs to the BI-1 family of proteins, which contain BI-1-like transmembrane domains. As their cellular functions and regulatory mechanisms remain incompletely understood, we compared their anti-apoptotic properties. Forced expression of BI-1 resulted in the most effective suppression of stress-induced apoptosis, compared with other family members, together with significant extracellular signal-regulated kinase (ERK)1/2 activation. BI-1-mediated ERK1/2 activation led to the suppression of mitochondria-mediated reactive oxygen species (ROS) production. Involvement of the ERK signaling pathway in BI-1-induced anti-apoptotic effects was confirmed by knockdown studies with ERK- or BI-1-specific siRNA. Moreover, we produced transgenic (TG) mice overexpressing BI-1, and the relationship between ERK1/2 activation and the suppression of ROS production or apoptosis was confirmed in mouse embryonic fibroblast (MEF) cells derived from these mice. Interestingly, we found that BI-1 TG mice showed splenomegaly and abnormal megakaryopoiesis. Taken together, our results suggest that BI-1-induced ERK1/2 activation plays an important role in the modulation of intracellular ROS generation and apoptotic cell death and may also affect autoimmune response. 相似文献
956.
High-performance muscles such as the shaker muscles in the tails of western diamond-backed rattlesnakes (Crotalus atrox) are excellent systems for studying the relationship between contractile performance and metabolic capacity. We observed that shaker muscle contraction frequency increases dramatically with growth in small individuals but then declines gradually in large individuals. We tested whether metabolic capacity changed with performance, using shaker muscle contraction frequency as an indicator of performance and maximal activities of citrate synthase and lactate dehydrogenase as indicators of aerobic and anaerobic capacities, respectively. Contraction frequency increased 20-fold in 20-100-g individuals but then declined by approximately 30% in individuals approaching 1,000 g. Mass-independent aerobic capacity was positively correlated with contractile performance, whereas mass-independent anaerobic capacity was slightly but negatively correlated with performance; body mass was not correlated with performance. Rattle mass increased faster than the ability to generate force. Early in ontogeny, shaker muscle performance appears to be limited by aerobic capacity, but later performance becomes limited equally by aerobic capacity and the mechanical constraint of moving a larger mass without proportionally thicker muscles. This high-performance muscle appears to shift during ontogeny from a metabolic constraint to combined metabolic and mechanical constraints. 相似文献
957.
958.
959.
Young Bin Hong Jaesoon Joo Young Se Hyun Geon Kwak Yu-Ri Choi Ha Kyung Yeo Dong Hwan Jwa Eun Ja Kim Won Min Mo Soo Hyun Nam Sung Min Kim Jeong Hyun Yoo Heasoo Koo Hwan Tae Park Ki Wha Chung Byung-Ok Choi 《PLoS genetics》2016,12(2)
Charcot-Marie-Tooth disease (CMT) is a heterogeneous group of peripheral neuropathies with diverse genetic causes. In this study, we identified p.I43N mutation in PMP2 from a family exhibiting autosomal dominant demyelinating CMT neuropathy by whole exome sequencing and characterized the clinical features. The age at onset was the first to second decades and muscle atrophy started in the distal portion of the leg. Predominant fatty replacement in the anterior and lateral compartment was similar to that in CMT1A caused by PMP22 duplication. Sural nerve biopsy showed onion bulbs and degenerating fibers with various myelin abnormalities. The relevance of PMP2 mutation as a genetic cause of dominant CMT1 was assessed using transgenic mouse models. Transgenic mice expressing wild type or mutant (p.I43N) PMP2 exhibited abnormal motor function. Electrophysiological data revealed that both mice had reduced motor nerve conduction velocities (MNCV). Electron microscopy revealed that demyelinating fibers and internodal lengths were shortened in both transgenic mice. These data imply that overexpression of wild type as well as mutant PMP2 also causes the CMT1 phenotype, which has been documented in the PMP22. This report might expand the genetic and clinical features of CMT and a further mechanism study will enhance our understanding of PMP2-associated peripheral neuropathy. 相似文献
960.