全文获取类型
收费全文 | 3192篇 |
免费 | 426篇 |
出版年
2021年 | 45篇 |
2020年 | 31篇 |
2019年 | 39篇 |
2018年 | 49篇 |
2017年 | 35篇 |
2016年 | 85篇 |
2015年 | 98篇 |
2014年 | 110篇 |
2013年 | 152篇 |
2012年 | 161篇 |
2011年 | 145篇 |
2010年 | 96篇 |
2009年 | 93篇 |
2008年 | 140篇 |
2007年 | 164篇 |
2006年 | 137篇 |
2005年 | 129篇 |
2004年 | 131篇 |
2003年 | 105篇 |
2002年 | 120篇 |
2001年 | 84篇 |
2000年 | 62篇 |
1999年 | 75篇 |
1998年 | 49篇 |
1997年 | 38篇 |
1996年 | 35篇 |
1995年 | 41篇 |
1994年 | 38篇 |
1993年 | 36篇 |
1992年 | 74篇 |
1991年 | 55篇 |
1990年 | 57篇 |
1989年 | 59篇 |
1988年 | 50篇 |
1987年 | 54篇 |
1986年 | 45篇 |
1985年 | 56篇 |
1984年 | 40篇 |
1983年 | 42篇 |
1982年 | 36篇 |
1981年 | 35篇 |
1980年 | 28篇 |
1979年 | 28篇 |
1978年 | 24篇 |
1977年 | 30篇 |
1976年 | 23篇 |
1974年 | 26篇 |
1973年 | 28篇 |
1972年 | 24篇 |
1969年 | 23篇 |
排序方式: 共有3618条查询结果,搜索用时 15 毫秒
1.
G S Aulakh E B Stephens D L Rose J G Tully M F Barile 《Journal of bacteriology》1983,153(3):1338-1341
3H-labeled Acholeplasma DNA probes were generated in vitro by the nick-translation method and used to determine the nucleotide sequence homology among the type strains of the eight currently recognized species of Acholeplasma. Very little nucleotide sequence homology (less than or equal to 18%) was found among the eight species, with heteroduplexes showing at least 12% or more mismatching as determined by thermal elution midpoints. The small amount of nucleotide sequence homology among the eight species indicates that these species are quite distinct and are not closely related to each other genomically. 相似文献
2.
Peter J Stephens 《BMJ (Clinical research ed.)》2005,330(7506):1508-1509
3.
4.
5.
6.
Food sharing: a model of manipulation by harassment 总被引:3,自引:1,他引:2
Most analyses of food-sharing behavior invoke complex explanationssuch as indirect and delayed benefits for sharing via kin selectionand reciprocal altruism. However, food sharing can be a moregeneral phenomenon accounted for by more parsimonious, mutualisticexplanations. We propose a game theoretical model of a generalsharing situation in which food owners share because it is
in their own self-interestthey avoid high costs associatedwith beggar harassment. When beggars harass, owners may benefitfrom sharing part of the food if their consumption rate islow relative to the rate of cost accrual. Our model predictsthat harassment can be a profitable strategy for beggars if
they reap some direct benefits from harassing other than sharedfood (such as picking up scraps). Therefore, beggars may manipulatethe owner's fitness payoffs in such a way as to make sharingmutualistic. 相似文献
7.
C A Tyson D L Story R J Stephens 《Biochemical and biophysical research communications》1983,114(2):511-517
Ultrastructural data are presented on time-course changes in isolated rat hepatocyte suspensions exposed either to 1.2 or 1.8 mM CCl4 for up to 1 h. The subcellular changes at the lower concentration, but not the higher, are shown to closely parallel those reported to occur in rat hepatocytes following ingestion of CCl4. 相似文献
8.
Secretion of Recombinant Pediocin PA-1 by Bifidobacterium longum, Using the Signal Sequence for Bifidobacterial α-Amylase 下载免费PDF全文
Gi-Seong Moon Yu-Ryang Pyun Myeong Soo Park Geun Eog Ji Wang June Kim 《Applied microbiology》2005,71(9):5630-5632
A recombinant DNA, encoding the chimeric protein of the signal sequence for bifidobacterial α-amylase mature pediocin PA-1, was introduced into Bifidobacterium longum MG1. Biologically active pediocin PA-1 was successfully secreted from the strain and showed bactericidal activity against Listeria monocytogenes and the same molecular mass as native pediocin PA-1. 相似文献
9.
10.