全文获取类型
收费全文 | 464篇 |
免费 | 49篇 |
专业分类
513篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 11篇 |
2020年 | 5篇 |
2019年 | 12篇 |
2018年 | 16篇 |
2017年 | 16篇 |
2016年 | 10篇 |
2015年 | 22篇 |
2014年 | 30篇 |
2013年 | 28篇 |
2012年 | 39篇 |
2011年 | 28篇 |
2010年 | 19篇 |
2009年 | 23篇 |
2008年 | 21篇 |
2007年 | 27篇 |
2006年 | 22篇 |
2005年 | 15篇 |
2004年 | 18篇 |
2003年 | 15篇 |
2002年 | 16篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 9篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 8篇 |
1989年 | 2篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1977年 | 6篇 |
1974年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1966年 | 3篇 |
1937年 | 1篇 |
1933年 | 2篇 |
排序方式: 共有513条查询结果,搜索用时 0 毫秒
101.
Williams TM Rutishauser M Long B Fink T Gafney J Mostman-Liwanag H Casper D 《Physiological and biochemical zoology : PBZ》2007,80(4):433-443
Otariids, like other wild mammals, contend with a wide variety of energetic demands across seasons. However, due to the cryptic behaviors of this marine group, few studies have been able to examine longitudinal energetic costs or the potential impact of these costs on seasonal or annual prey requirements. Here we evaluated the changes in energy demand and intake of female California sea lions (Zalophus californianus) during reproductive (n=2 sea lions) and nonreproductive (n=3) periods. Monthly measurements included resting metabolic rate, blood hormone levels, body condition (blubber thickness and body mass), and caloric intake for adult sea lions throughout molting, late pregnancy, lactation, and postweaning. We found that maintenance energy demands decreased from 32.0 to 23.1 MJ d(-1) before pupping, remaining stable at 19.4+/-0.6 MJ d(-1) during lactation and postweaning. Energy intake rates to meet these demands showed marked changes with activity level and the reproductive cycle, reaching a peak intake of 3.6 times baseline levels during lactation. Translating this into prey demands, we find that 20,000 reproductively active females on San Nicolas Island rookeries would maximally require 4,950 metric tons of Pacific whiting during a month of the breeding season. This localized impact is reduced significantly with postbreeding dispersal and demonstrates the importance of considering spatial and temporal factors driving the energetic requirements of predators when designing marine protected areas. 相似文献
102.
103.
High-rate evolution of Saccharomyces sensu lato chromosomes 总被引:1,自引:0,他引:1
Spírek M Yang J Groth C Petersen RF Langkjaer RB Naumova ES Sulo P Naumov GI Piskur J 《FEMS yeast research》2003,3(4):363-373
104.
105.
106.
Olaf Brouwers Liang Yu Petra Niessen Jos Slenter Karolien Jaspers Allard Wagenaar Mark Post Toshio Miyata Walter Backes Coen Stehouwer Maya Huijberts Casper Schalkwijk 《Glycoconjugate journal》2016,33(4):627-630
We hypothesize that diabetes-induced impaired collateral formation after a hindlimb ligation in rats is in part caused by intracellular glycation and that overexpression of glyoxalase-I (GLO-I), i.e. the major detoxifying enzyme for advanced-glycation-endproduct (AGE) precursors, can prevent this. Wild-type and GLO-I transgenic rats with or without diabetes (induced by 55 mg/kg streptozotocin) were subjected to ligation of the right femoral artery. Laser Doppler perfusion imaging showed a significantly decreased blood perfusion recovery after 6 days in the diabetic animals compared with control animals, without any effect of Glo1 overexpression. In vivo time-of-flight magnetic resonance angiography at 7-Tesla showed a significant decrease in the number and volume of collaterals in the wild-type diabetic animals compared with the control animals. Glo1 overexpression partially prevented this decrease in the diabetic animals. Diabetes-induced impairment of arteriogenic adaptation can be partially rescued by overexpressing of GLO-I, indicating a role of AGEs in diabetes-induced impaired collateral formation. 相似文献
107.
The general control of amino acid biosynthesis was investigated in Candida spec. EH 15/D, using single and double mutant auxotrophic strains and prototrophic revertants starved for their required amino acids. These experiments show that starvation for lysine, histidine, arginine, leucine, threonine, proline, serine, methionine, homoserine, asparagine, glutamic acid or aspartic acid can result in derepression of enzymes. A correlation was found between the degree of derepression, growth of strains, and concentration of required amino acids. The amino acids pool pattern of mutants and revertants is different from that in the wild type strain. 相似文献
108.
109.
Genomic RNA of plum pox virus (PPV) was used as a template for the synthesis of complementary DNA (cDNA). The generated cDNA molecules were subsequently cloned into pBR 322. A physical map covering 9700 bases of the PPV genome was constructed from 8, clones by hybridization and restriction endonuclease digestion. Clone pPPV-NAT 309, starting at the 3′-end, with an 866 bp insert was used in Northern- and Dot-hybridizations for the detection of single-stranded viral RNA in total nucleic acid as well as in sap preparations of PPV infected Nicotiana clevelandii. The nucleotide sequence of this clone was determined, the amino acid sequence of the coat protein C-terminal part was deduced and compared with four other coat proteins of potyviruses. 相似文献
110.