全文获取类型
收费全文 | 6012篇 |
免费 | 650篇 |
国内免费 | 1篇 |
出版年
2021年 | 54篇 |
2019年 | 47篇 |
2018年 | 61篇 |
2017年 | 48篇 |
2016年 | 97篇 |
2015年 | 145篇 |
2014年 | 190篇 |
2013年 | 262篇 |
2012年 | 307篇 |
2011年 | 343篇 |
2010年 | 212篇 |
2009年 | 194篇 |
2008年 | 312篇 |
2007年 | 371篇 |
2006年 | 305篇 |
2005年 | 339篇 |
2004年 | 311篇 |
2003年 | 318篇 |
2002年 | 289篇 |
2001年 | 61篇 |
1999年 | 80篇 |
1998年 | 90篇 |
1997年 | 63篇 |
1996年 | 70篇 |
1995年 | 69篇 |
1994年 | 58篇 |
1993年 | 56篇 |
1992年 | 67篇 |
1991年 | 55篇 |
1990年 | 56篇 |
1989年 | 51篇 |
1988年 | 58篇 |
1987年 | 51篇 |
1986年 | 47篇 |
1985年 | 62篇 |
1984年 | 88篇 |
1983年 | 61篇 |
1982年 | 78篇 |
1981年 | 102篇 |
1980年 | 87篇 |
1979年 | 52篇 |
1978年 | 69篇 |
1977年 | 73篇 |
1976年 | 58篇 |
1975年 | 60篇 |
1974年 | 73篇 |
1973年 | 49篇 |
1970年 | 53篇 |
1969年 | 55篇 |
1967年 | 50篇 |
排序方式: 共有6663条查询结果,搜索用时 375 毫秒
11.
A previous experiment(Herzfeld & Taub, 1977) demonstrated that slide projections and explicit suggestions relating to thermal experiences can significantly augment temperature self-regulations training(.5° F,p<.05). However, the experimental design was thought to result in an underestimate of the magnitude of the effect, since each subject served as his own control and could therefore make use on nonsuggestion training days of material provided on training days. In this experiment, separate groups of subjects either were given feedback combined with the suggestion procedure on each of 8 training days or were given feedback alone. The mean temperature self-regulation of the suggestion group(2.01° F) was significantly better than the self-regulation(.73) of the nonsuggestion group(t test,p<.01).a difference of 1.28° F. 相似文献
12.
Summary Osteogenesis imperfecta (OI) is a phenotype with clinical and biochemical heterogeneity. We report here that expression of the OI phenotype extends to the level of dermal fibroblast morphology in vitro. Growth characteristics and morphology of control (n=6) and OI cell strains (n=10, representing the four major OI categories, Sillence classification) were compared by measuring the following: (i) days required in culture to reach confluence after plating at uniform density; (ii) cell density at confluence; (iii) width and length of cells (measured on phase contrast micrographs at 300xmagnification). Our results show that: (i) OI fibroblasts take longer (11–27 days, mean 20 days) than control cells (10–19 days, mean 16 days) to reach stationary phase; (ii) all OI phenotypes achieve a lower cell density (0.87x106 cells/P60, range 0.3–1.6x106) at stationary phase relative to control cells (2.2x106 cells/P60, range 1.7–2.6x106; F4,77=56.1, p<0.01, indicating that OI cells are larger than normal). Cell shape (expressed as the width: length ratio) was also abnormal in OI cells. (F4,730=37.6, p<0.01), types I and II OI cells have significantly increased ratios (p<0.01) relative to control, type III, and type IV cells. Intra-group phenotypic heterogeneity was also apparent in the OI categories and also within the control population. These findings confirm deviant morphologic phenotypes in OI dermal fibroblasts and further demonstrate interindividual heterogeneity in the expression of genes that determine size and shape of dermal fibroblasts in both OI and normal donors.Publication No. 84013 from the Montreal Children's Hospital Research Institute 相似文献
13.
14.
Dennis W. Jung Gerald P. Brierley 《Biochemical and biophysical research communications》1982,106(4):1372-1377
Heart mitochondria respiring in the presence of Pi release endogenous K+ to a sucrose medium when an uncoupler is added. The uncoupled mitochondria retain K+, however, if the oxidation of NAD(P)H is prevented by the addition of rotenone or antimycin. Addition of rotenone, once the uncoupler-dependent K+-efflux has been initiated, results in a rapid reduction of NAD(P) and a simultaneous decrease in permeability to K+. These changes are independent of respiration. The results suggest that a latent pathway for K+-permeability is present in the membrane, that it can be opened and closed reversibly, and that it reflects, either directly or indirectly, the redox status of mitochondrial pyridine nucleotides. The possible relationship of this putative pathway to those available for Ca2+ uptake and release is considered. 相似文献
15.
Gerald Ozanne 《Aerobiologia》1990,6(1):8-10
Summary Under the ?Bois plus? scheme, the CTBA is currently developing a third party certification, based on the Scrivener law, with the aim of defending
the consumers' interests. At this early stage, wood preservatives and treated wood are checked for the efficacy of treatments
in order to ensure the stability and security of works in buildings and civil engineering. According to the different classes
of risks in service, ?Bois plus? provides the most adeguate level of protection. In the close future, the industry is planning to incorporate, with the help
of the CTBA and experts, health criteria within the frame of the ?Bois plus? certification scheme. The means could beSafety indexes, which are objectives of quality for professionals.Safety indexes are concentrations of substances in wood which can be taken as safe for humans and the general environment, while still toxic
for the wood pests.
This attractive experience aims to make with the brandname ?Bois plus? a synonym of efficacy and safety. This approach meets the essential requirements 1, 3, 4 of the 89/106 EEC directive: mechanical
resistance and stability/hygiene, health and environment/safety in use. 相似文献
16.
17.
Recently we demonstrated that ethidium bromide altered the plasma and subcellular membrane glycoproteins in control and virus transformed cells. It is reported here that ethidium bromide also stimulated the membrane associated process of sugar transport. The Km of the virus transformed cells and the ethidium bromide treated cells is the same as that of the control cells while the maximum velocity as compared to the control cells is significantly increased. The transport of 2-deoxy-D-glucose was inhibited by glucose, cytochalasin B and neuraminidase but was unaffected by variations in cell density or pH of the incubation medium. 相似文献
18.
19.
Gerhart Drews 《Archives of microbiology》1981,130(4):325-327
The name Rhodospirillum salexigens, spec. nov., was proposed for the strain WS 68, isolated by W. R. Sistrom at the Oregon coast from salt water. The spiral-shaped phototrophically or chemotrophically growing, salt demanding bacterium contains intracytoplasmic membranes arranged parallel to the cytoplasmic membrane. Bacteriochlorophyll a and spirilloxanthin are the major pigments. Growth occurs between 20 and 45°C at a neutral pH. The DNA base composition was 64 mol % guanine plus cytosine. The cell wall contains peptidoglycan and proteins but no glycolipids. 相似文献
20.