全文获取类型
收费全文 | 59494篇 |
免费 | 5694篇 |
国内免费 | 22篇 |
出版年
2023年 | 243篇 |
2022年 | 503篇 |
2021年 | 1005篇 |
2020年 | 632篇 |
2019年 | 807篇 |
2018年 | 992篇 |
2017年 | 864篇 |
2016年 | 1476篇 |
2015年 | 2442篇 |
2014年 | 2706篇 |
2013年 | 3158篇 |
2012年 | 4211篇 |
2011年 | 4073篇 |
2010年 | 2581篇 |
2009年 | 2346篇 |
2008年 | 3384篇 |
2007年 | 3433篇 |
2006年 | 3260篇 |
2005年 | 3092篇 |
2004年 | 3029篇 |
2003年 | 2772篇 |
2002年 | 2706篇 |
2001年 | 872篇 |
2000年 | 713篇 |
1999年 | 815篇 |
1998年 | 854篇 |
1997年 | 589篇 |
1996年 | 513篇 |
1995年 | 470篇 |
1994年 | 498篇 |
1993年 | 494篇 |
1992年 | 623篇 |
1991年 | 499篇 |
1990年 | 486篇 |
1989年 | 490篇 |
1988年 | 440篇 |
1987年 | 408篇 |
1986年 | 403篇 |
1985年 | 377篇 |
1984年 | 434篇 |
1983年 | 398篇 |
1982年 | 419篇 |
1981年 | 382篇 |
1980年 | 395篇 |
1979年 | 310篇 |
1978年 | 299篇 |
1977年 | 263篇 |
1976年 | 257篇 |
1974年 | 233篇 |
1973年 | 208篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
133.
Techniques are described for capturing and marking redtail monkeys (Cercopithecus ascanius). An air-powered darting rifle and syringe darts loaded with a Ketamine-Rompun mixture were used for capture. Ketamine was used for maintaining anesthesia. Monkeys were darted 48 times and captured 27 times. In 24 of the 27 captures, the monkeys were released unharmed. Adult males were marked with radiotransmitters attached to collars of nylon webbing. Females received nylon webbing collars with colorcoded plastic washers for identification. 相似文献
134.
135.
136.
Markus Pech Thomas Spreter Roland Beckmann Birgitta Beatrix 《The Journal of biological chemistry》2010,285(25):19679-19687
Nascent polypeptide-associated complex (NAC) was identified in eukaryotes as the first cytosolic factor that contacts the nascent polypeptide chain emerging from the ribosome. NAC is present as a homodimer in archaea and as a highly conserved heterodimer in eukaryotes. Mutations in NAC cause severe embryonically lethal phenotypes in mice, Drosophila melanogaster, and Caenorhabditis elegans. In the yeast Saccharomyces cerevisiae NAC is quantitatively associated with ribosomes. Here we show that NAC contacts several ribosomal proteins. The N terminus of βNAC, however, specifically contacts near the tunnel exit ribosomal protein Rpl31, which is unique to eukaryotes and archaea. Moreover, the first 23 amino acids of βNAC are sufficient to direct an otherwise non-associated protein to the ribosome. In contrast, αNAC (Egd2p) contacts Rpl17, the direct neighbor of Rpl31 at the ribosomal tunnel exit site. Rpl31 was also recently identified as a contact site for the SRP receptor and the ribosome-associated complex. Furthermore, in Escherichia coli peptide deformylase (PDF) interacts with the corresponding surface area on the eubacterial ribosome. In addition to the previously identified universal adapter site represented by Rpl25/Rpl35, we therefore refer to Rpl31/Rpl17 as a novel universal docking site for ribosome-associated factors on the eukaryotic ribosome. 相似文献
137.
Growth characteristics of a thermotolerant methylotrophic Bacillus sp. (NCIB 12522) in batch culture
Nader Al-Awadhi Thomas Egli Geoffrey Hamer 《Applied microbiology and biotechnology》1988,29(5):485-493
Summary This contribution deals with problems associated with the culture of a thermotolerant methylotrophic Bacillus sp. The results reported clearly demonstrate why conventional enrichment/isolation procedures have, in the past, failed to allow such microbes to assert themselves. The catastrophic effect of carbon substrate (methanol) exhaustion on such cultures is clearly evidenced, but the effects of other nutrient exhaustion or limitations are demonstrated to be markedly less stringent. The failure of such cultures to complete the sporulation process when growing on methanol has important consequences with respect to their survival characteristics. 相似文献
138.
The presence or absence of light during flotation restricted environmental stimulation: Effects on plasma cortisol,blood pressure,and mood 总被引:1,自引:0,他引:1
John W. Turner Jr. Thomas Fine Gina Ewy Peter Sershon Thomas Freundlich 《Applied psychophysiology and biofeedback》1989,14(4):291-300
This study examined the effect of light on relaxation associated with flotation restricted environmental stimulation therapy (REST), as measured by plasma cortisol, mean arterial pressure, and psychometric parameters. Twenty-one subjects were paired by baseline cortisol levels into two groups: one experiencing flotation REST in the presence of light (REST-L) and one experiencing flotation REST in the absence of light (REST-D). Subjects were 15 male and 6 female students aged 22–28 in normal health who had not experienced REST. Repeated flotation REST (8 sessions) either with light or without light was associated with a decrease in plasma cortisol and a decrease in mean arterial pressure, with no differences in effectiveness between groups. The psychometric assessment of mood, using the POMS scale, before and after sessions 1 and 8 revealed mood state improvement in both REST-L and REST-D groups. These data suggest that the presence of light did not compromise the flotation REST experience, as evidenced by the lack of difference between REST-L and REST-D groups. 相似文献
139.
140.