全文获取类型
收费全文 | 8988篇 |
免费 | 995篇 |
国内免费 | 1篇 |
出版年
2021年 | 105篇 |
2019年 | 71篇 |
2018年 | 117篇 |
2017年 | 111篇 |
2016年 | 150篇 |
2015年 | 277篇 |
2014年 | 300篇 |
2013年 | 400篇 |
2012年 | 450篇 |
2011年 | 452篇 |
2010年 | 295篇 |
2009年 | 238篇 |
2008年 | 395篇 |
2007年 | 442篇 |
2006年 | 382篇 |
2005年 | 392篇 |
2004年 | 344篇 |
2003年 | 328篇 |
2002年 | 312篇 |
2001年 | 187篇 |
2000年 | 196篇 |
1999年 | 165篇 |
1998年 | 134篇 |
1997年 | 134篇 |
1996年 | 120篇 |
1995年 | 103篇 |
1994年 | 124篇 |
1993年 | 107篇 |
1992年 | 176篇 |
1991年 | 137篇 |
1990年 | 124篇 |
1989年 | 128篇 |
1988年 | 119篇 |
1987年 | 135篇 |
1986年 | 107篇 |
1985年 | 148篇 |
1984年 | 155篇 |
1983年 | 111篇 |
1982年 | 132篇 |
1981年 | 119篇 |
1980年 | 109篇 |
1979年 | 102篇 |
1978年 | 75篇 |
1977年 | 75篇 |
1976年 | 85篇 |
1975年 | 66篇 |
1974年 | 84篇 |
1973年 | 74篇 |
1972年 | 63篇 |
1971年 | 61篇 |
排序方式: 共有9984条查询结果,搜索用时 13 毫秒
1.
2.
Donald E. Rivett Dean Hewish Alan Kirkpatrick Jerome Werkmeister 《Journal of Protein Chemistry》1999,18(3):291-295
Nine fatty acid–peptide hybrid molecules were constructed using the general formula CH3(CH2)
n
CO-Phe Asp Cys-amide and tested for their ability to inhibit cell lysis induced by the membrane-active peptide melittin. All of these molecules, where n = 4–14, inhibited the action of melittin to some extent, but the longer carbon chains were most effective. Several potential inhibitors were also constructed with conservative substitutions in the peptide portion of the molecule. All were effective to varying degrees. We concluded that in the hexapeptide inhibitor published by Blondelle et al. (1993), the role of the first three residues is only to provide hydrophobic interaction with the melittin and has no particular amino acid sequence specificity. Some of these inhibitors were found to inhibit the lytic activity of a melittin analogue which had only superficial sequence similarity to melittin and also a truncated form of melittin, indicating the generality of the action of the inhibitors.Deceased 5/4/98 相似文献
3.
Keratinocyte growth-promoting activity from human placenta 总被引:4,自引:0,他引:4
Extracts of term human placenta were tested for enhancement of proliferative growth of primary cultures of human keratinocytes. Saline extracts or supernatants from homogenates were dialyzed extensively, lyophilized, and tested in subcultures of keratinocytes in MCDB 153 medium with 0.1 mM Ca++ containing only defined supplements (insulin, hydrocortisone, transferrin, ethanolamine, phosphoethanolamine). Cells plated in the absence of EGF at moderately high densities (1000-3000 cells per cm2) formed colonies and grew in the presence of placental extract at 25-500 micrograms/ml. Extracts of cord serum or maternal serum were inactive, suggesting that the activity is derived from placental tissue. The activity is not EGF, since the activity in the placental extract, unlike EGF, did not promote growth at low cell density, was synergistic with EGF under some conditions, and did not produce changes in colonial morphology which occurred in the presence of EGF. Unlike keratinocyte growth-promoting activity in bovine hypothalamic extract, the activity is non-dialyzable and is destroyed at 100 degrees C. Placental extract could not replace any of the defined components of the medium and is therefore distinct from them. The presence of activity in the placenta with distinctive properties suggests that this is a previously undescribed material with growth-promoting properties for epithelium. 相似文献
4.
5.
6.
Mark Kirkpatrick Stephan Peischl 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2013,368(1610)
A factor that may limit the ability of many populations to adapt to changing conditions is the rate at which beneficial mutations can become established. We study the probability that mutations become established in changing environments by extending the classic theory for branching processes. When environments change in time, under quite general conditions, the establishment probability is approximately twice the ‘effective selection coefficient’, whose value is an average that gives most weight to a mutant''s fitness in the generations immediately after it appears. When fitness varies along a gradient in a continuous habitat, increased dispersal generally decreases the chance a mutation establishes because mutations move out of areas where they are most adapted. When there is a patch of favourable habitat that moves in time, there is a maximum speed of movement above which mutations cannot become established, regardless of when and where they first appear. This critical speed limit, which is proportional to the mutation''s maximum selective advantage, represents an absolute constraint on the potential of locally adapted mutations to contribute to evolutionary rescue. 相似文献
7.
8.
William Russell 《BMJ (Clinical research ed.)》1985,290(6485):1914
9.
10.
Hanna G. Budayeva Arundhati Sengupta-Ghosh Lilian Phu John G. Moffat Gai Ayalon Donald S. Kirkpatrick 《Molecular & cellular proteomics : MCP》2022,21(4):100221
Muscle-specific receptor tyrosine kinase (MuSK) agonist antibodies were developed 2 decades ago to explore the benefits of receptor activation at the neuromuscular junction. Unlike agrin, the endogenous agonist of MuSK, agonist antibodies function independently of its coreceptor low-density lipoprotein receptor–related protein 4 to delay the onset of muscle denervation in mouse models of ALS. Here, we performed dose–response and time-course experiments on myotubes to systematically compare site-specific phosphorylation downstream of each agonist. Remarkably, both agonists elicited similar intracellular responses at known and newly identified MuSK signaling components. Among these was inducible tyrosine phosphorylation of multiple Rab GTPases that was blocked by MuSK inhibition. Importantly, mutation of this site in Rab10 disrupts association with its effector proteins, molecule interacting with CasL 1/3. Together, these data provide in-depth characterization of MuSK signaling, describe two novel MuSK inhibitors, and expose phosphorylation of Rab GTPases downstream of receptor tyrosine kinase activation in myotubes. 相似文献