全文获取类型
收费全文 | 3489篇 |
免费 | 441篇 |
国内免费 | 3篇 |
出版年
2021年 | 51篇 |
2019年 | 40篇 |
2018年 | 49篇 |
2017年 | 38篇 |
2016年 | 76篇 |
2015年 | 126篇 |
2014年 | 133篇 |
2013年 | 142篇 |
2012年 | 189篇 |
2011年 | 194篇 |
2010年 | 123篇 |
2009年 | 109篇 |
2008年 | 139篇 |
2007年 | 174篇 |
2006年 | 132篇 |
2005年 | 159篇 |
2004年 | 143篇 |
2003年 | 133篇 |
2002年 | 117篇 |
2001年 | 89篇 |
2000年 | 67篇 |
1999年 | 80篇 |
1998年 | 44篇 |
1997年 | 44篇 |
1996年 | 36篇 |
1995年 | 35篇 |
1994年 | 28篇 |
1993年 | 33篇 |
1992年 | 62篇 |
1991年 | 55篇 |
1990年 | 60篇 |
1989年 | 51篇 |
1988年 | 45篇 |
1987年 | 46篇 |
1986年 | 40篇 |
1985年 | 54篇 |
1984年 | 43篇 |
1983年 | 43篇 |
1982年 | 32篇 |
1981年 | 28篇 |
1980年 | 29篇 |
1979年 | 42篇 |
1978年 | 28篇 |
1977年 | 36篇 |
1976年 | 34篇 |
1974年 | 38篇 |
1973年 | 37篇 |
1972年 | 34篇 |
1971年 | 42篇 |
1966年 | 33篇 |
排序方式: 共有3933条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Páraic ó Cuív Rajesh Gupta Hareshwar P. Goswami Mark Morrison 《Applied and environmental microbiology》2013,79(19):6173-6175
Clostridium thermocellum encodes a cellulosomal, modular, and thermostable serine protease inhibitor (serpin), PinA. PinA stability but not inhibitory activity is affected by the Fn(III) and Doc(I) domains, and PinA is a broad inhibitor of subtilisin-like proteases and may play a key role in protecting the cellulosome from protease attack. 相似文献
5.
Solange Faria Lua Figueiredo Norma Albarello Vera Regina Campos Viana 《In vitro cellular & developmental biology. Plant》2001,37(4):471-475
Summary A protocol for in vitro propagation of Rollinia mucosa, an important medicinal plant, was developed. The presence of 500 mg l−1 polyvinylpyrrolidone (PVP) during explant excision was important to avoid browning. Axillary buds, adventitious buds, and
shoot cluster proliferation were achieved from epicotyl and hypocotyl explants from nursery-grown seedlings. The highest direct
organogenesis percentage from hypocotyl explants was obtained upon culture of explants on Murashige and Skoog medium supplemented
with 2.2 μM benzyladenine (BA) plus 2.32 μM kinetin. Epicotyl explants display highest regeneration frequency on a medium containing 8.8 μM BA and 0.54 μM naphthaleneacetic acid. Gibberellic acid was necessary for shoot elongation. Root induction was observed when shoots were
pretreated with activated charcoal for 7 d in the dark before culture on Woody Plant Medium supplemented with 49.21 μM indolebutyric acid for 10 d. Root development was observed when 20 g l−1 sucrose was used. Rooted plantlets were acclimatized and grown in the greenhouse. 相似文献
6.
Norma Lake 《Neurochemical research》1982,7(11):1385-1390
Taurine is the major free amino acid of the vertebrate retina. Treatment of rats with guanidinoethyl sulfonate (GES), a taurine analogue which competes with taurine for transport sites, leads to depletion of 60% of retinal taurine with little effect on other free amino acids. Supplementation of the diet with 0.3% taurine gives partial protection against depletion, confirming that taurine-GES competition underlies part of the effects. The magnitude of the depletion suggests the importance of taurine transport across the blood-retinal barrier for the maintenance of retinal taurine levels. 相似文献
7.
Li Zhang Mark Morrison Páraic ó Cuív Paul Evans Claire M. Rickard 《Journal of bacteriology》2012,194(23):6639
In recent years, Staphylococcus epidermidis has become a major nosocomial pathogen and the most common cause of intravascular catheter-related bacteremia, which can increase morbidity and mortality and significantly affect patient recovery. We report a draft genome sequence of Staphylococcus epidermidis AU12-03, isolated from an intravascular catheter tip. 相似文献
8.
Susan Morrison Grace John-Stewart John J. Egessa Sezi Mubezi Sylvia Kusemererwa Dennis K. Bii Nulu Bulya Francis Mugume James D. Campbell Jonathan Wangisi Elizabeth A. Bukusi Connie Celum Jared M. Baeten Partners PrEP Study Team 《PloS one》2015,10(10)
During an HIV-1 prevention clinical trial in East Africa, we observed 16 cases of primary HIV-1 infection in women coincident with pregnancy or breastfeeding. Nine of eleven pregnant women initiated rapid combination antiretroviral therapy (ART), despite having CD4 counts exceeding national criteria for ART initiation; breastfeeding women initiated ART or replacement feeding. Rapid ART initiation during primary HIV-1 infection during pregnancy and breastfeeding is feasible in this setting. 相似文献
9.
P D Blanchard R A Angus R L Morrison S K Frost-Mason J H Sheetz 《Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society》1991,4(5-6):240-246
Electron micrographs of skin from xanthic (gold) sailfin mollies revealed numerous xanthophores, as well as scattered melanophores. The melanophores were seen to contain premelanosomes in various stages of development. This is consistent with the fact that xanthic mollies have been shown to be tyrosinase positive. Melanosomes in xanthic mollies appear to develop by one of two pathways: 1) from an endoplasmic reticulum-derived vesicle which develops an internal lamellar framework, and 2) by fusion of multiple Golgi-derived vesicles which lack an internal lamellar framework. Analysis of the pigments in the skin of the xanthic mollies identified four colorless pteridine pigments (xanthopterin, isoxanthopterin, neopterin, and pterin) and a carotenoid with an absorbance spectrum similar to beta-carotene. It appears that, unlike some other poeciliid fishes, sailfin mollies do not use pteridine pigments for orange coloration. Rather, they appear to rely primarily on carotenoids. 相似文献
10.
We have compared the species richness of medicinal plants and the differential patterns of use amongst settlements in the
Andean communities of Northwest Argentina which have differing levels of isolation. About 259 ethnoespecies, belonging to
74 plant families, were included, representing between 70 and 80% of the total estimate. The results indicate that Coronopus didymus is the most relevant and important species. The method of use of medicinal plants and the ailments treated by rural doctors compared to those of the layperson is different. Native and exotic plants are used differently according to the body system
treated. There are some relationships between internal and external use and body systems and recipes. The greater medicinal
species richness found in the less isolated locations is due to external enriching cultural influences. 相似文献