全文获取类型
收费全文 | 3181篇 |
免费 | 191篇 |
国内免费 | 13篇 |
专业分类
3385篇 |
出版年
2024年 | 6篇 |
2023年 | 43篇 |
2022年 | 86篇 |
2021年 | 149篇 |
2020年 | 107篇 |
2019年 | 183篇 |
2018年 | 174篇 |
2017年 | 123篇 |
2016年 | 136篇 |
2015年 | 187篇 |
2014年 | 226篇 |
2013年 | 277篇 |
2012年 | 263篇 |
2011年 | 242篇 |
2010年 | 149篇 |
2009年 | 137篇 |
2008年 | 144篇 |
2007年 | 128篇 |
2006年 | 129篇 |
2005年 | 84篇 |
2004年 | 68篇 |
2003年 | 59篇 |
2002年 | 41篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 17篇 |
1998年 | 15篇 |
1997年 | 18篇 |
1996年 | 14篇 |
1995年 | 6篇 |
1994年 | 9篇 |
1993年 | 14篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1987年 | 8篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1972年 | 4篇 |
1971年 | 7篇 |
1970年 | 4篇 |
1969年 | 3篇 |
排序方式: 共有3385条查询结果,搜索用时 0 毫秒
81.
82.
83.
The aim of this study was to compare the physiological responses and energy cost between two ascending patterns, the single-step (SS) and the double-step (DS), in climbing a public staircase. In the SS pattern, a person climbs one step at a time whilst in the double-step (DS) pattern, the individual traverses two steps in a single stride. Advocates of each stepping pattern claimed that their type of ascent is physically more taxing and expends more calories. Thirty subjects (10 males and 20 females) climbed a typical 11-storey flat (each step height of 0.15 m, a total of 180 steps and a vertical displacement of 27.0 m). The subjects climbed using either the SS pattern at a tempo of 100 steps x min(-1) or the DS pattern at 50 steps x min(-1). The prescribed stepping frequencies ensured that an equal amount of total work was performed between the SS and DS patterns. The climbing patterns were performed in random order. Physiological measures during the last 30 s of the climbs were used in the comparative analysis. The results showed that ventilation, oxygen uptake and heart rate values were significantly higher (all p < 0.01) in the SS as compared to the DS pattern. However, the caloric expenditure during the SS pattern was calculated to be only marginally higher than the DS pattern. In conclusion, ascending with the SS pattern led to significantly higher physiological responses compared to the DS pattern. The higher calorie expended with the SS compared to the DS pattern was deemed to be of little practical significance. 相似文献
84.
85.
Mohammad Firdaus Bin Abdul Aziz Michael Morrison Jane Kaye 《New genetics and society》2018,37(1):2-20
Many “rising powers” such as India, China, Argentina, Singapore, and Brazil are investing in stem cell technology, joining the traditional leaders in the field, such as the UK, Germany, USA, and Japan. Malaysia is also entering this sector because of the potential medical and economic benefits that the use of stem cell technologies could provide. Like other countries, Malaysia faces the challenge of how to encourage scientific progress and innovation in an ethical manner while at the same time ensuring a safe and accessible market for regenerative therapies. This paper reports on the research findings of semi-structured interviews with local stakeholders to investigate how they perceived and evaluated the current regulatory framework for human stem cell research in Malaysia, and what might be at stake if the state continues with its current regulatory approach. 相似文献
86.
Plasmonics - Surface plasmon resonance is one of the important properties of noble metals which can be controlled by shape, size, and composition. This feature helps scientists to detect individual... 相似文献
87.
Hemagglutinin–neuraminidase (HN) protein besides its mediation in viral pathogenesis, is composed of various antigenic sites which stimulate production of host’s antibodies. Thus, application of this protein in serological tests and vaccination plays a major role in biosecurity and control programs. In the present study, we designed a recombinant HN protein containing different neutralizing antigenic sites with velogenic patterns, and sub-cloned it into pET-43.1a+ expression vector. The expression of NusA-HN recombinant protein was induced. Affinity chromatography protein purification using HisPur? Ni–NTA was then conducted. Moreover, we performed western-blot technique using HRP-conjugated Anti His-Tag. Results revealed that following induction of recombinant protein, two distinct bands of HN-61 kDa and NusA-63 kDa were purified and identified by western-blotting. We recommend further analysis should be carried out to determine the functional role of this recombinant protein in enzyme-linked immunosorbent assays for Newcastle disease diagnosis. This HN protein containing multi neutralizing antigenic sites might also be applicable in vaccination programs to increase vaccines potency. 相似文献
88.
Vahid Fadaei Naeini Masumeh Foroutan Mina Maddah Yves Rémond Majid Baniassadi 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(12):2815-2823
The inhibition of water permeation through aquaporins by ligands of pharmaceutical compounds is considered as a method to control the cell lifetime. The inhibition of aquaporin 1 (AQP1) by bacopaside-I and torsemide, was explored and its atomistic nature was elucidated by molecular docking and molecular dynamics (MD) simulation collectively along with Poisson-Boltzmann surface area (PBSA) method. Docking results revealed that torsemide has a lower level of docking energy in comparison with bacopaside-I at the cytoplasmic side. Furthermore, the effect of steric constraints on water permeation was accentuated. Bacopaside-I inhibits the channel properly due to the strong interaction with the channel and larger spatial volume, whereas torsemide blocks the cytoplasmic side of the channel imperfectly. The most probable active sites of AQP1 for the formation of hydrogen bonds between the inhibitor and the channel were identified by numerical analysis of the bonds. Eventually, free energy assessments indicate that binding of both inhibitors is favorable in complex with AQP1, and van der Waals interaction has an important contribution in stabilizing the complexes. 相似文献
89.
90.
Behrooz Soltani Narges Bodaghabadi Gita Mahpour Nasser Ghaemi Majid Sadeghizadeh 《Biotechnology letters》2016,38(12):2081-2088