全文获取类型
收费全文 | 731篇 |
免费 | 84篇 |
出版年
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 13篇 |
2017年 | 11篇 |
2016年 | 10篇 |
2015年 | 25篇 |
2014年 | 36篇 |
2013年 | 35篇 |
2012年 | 38篇 |
2011年 | 23篇 |
2010年 | 27篇 |
2009年 | 19篇 |
2008年 | 26篇 |
2007年 | 24篇 |
2006年 | 30篇 |
2005年 | 32篇 |
2004年 | 23篇 |
2003年 | 13篇 |
2002年 | 24篇 |
2001年 | 17篇 |
2000年 | 15篇 |
1999年 | 16篇 |
1998年 | 10篇 |
1997年 | 7篇 |
1996年 | 11篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 12篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1981年 | 6篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1975年 | 9篇 |
1974年 | 7篇 |
1973年 | 5篇 |
1969年 | 5篇 |
1909年 | 5篇 |
1905年 | 4篇 |
1904年 | 7篇 |
排序方式: 共有815条查询结果,搜索用时 15 毫秒
121.
122.
123.
Rats given either intragastric or intraventricular injections of clozapine showed a dose-dependent increase in food intake. 相似文献
124.
125.
Meng M. Rowland Joseph D. Schonhoft Paige L. McKibbin Sheila S. David James T. Stivers 《Nucleic acids research》2014,42(14):9295-9303
The DNA backbone is often considered a track that allows long-range sliding of DNA repair enzymes in their search for rare damage sites in DNA. A proposed exemplar of DNA sliding is human 8-oxoguanine (oG) DNA glycosylase 1 (hOGG1), which repairs mutagenic oG lesions in DNA. Here we use our high-resolution molecular clock method to show that macroscopic 1D DNA sliding of hOGG1 occurs by microscopic 2D and 3D steps that masquerade as sliding in resolution-limited single-molecule images. Strand sliding was limited to distances shorter than seven phosphate linkages because attaching a covalent chemical road block to a single DNA phosphate located between two closely spaced damage sites had little effect on transfers. The microscopic parameters describing the DNA search of hOGG1 were derived from numerical simulations constrained by the experimental data. These findings support a general mechanism where DNA glycosylases use highly dynamic multidimensional diffusion paths to scan DNA. 相似文献
126.
127.
The biological activities of a sterile red fungus (SRF) capable of plant growth promotion and suppression of take-all disease
were investigated in soils collected from Lancelin, Newdegate and Mt. Barker regions of Western Australia. Further, the effects
of three wheat cultivars and the presence of two isolates ofStreptomyces on the biological activities of the SRF were tested using the Lancelin soil. The biological activities of the SRF were greatest
in the Lancelin and Newdegate (wheat field) soils and with the wheat cultivar Gutha. In in vitro studies the soil streptomycetes
tested showed either a significant increase in the exudate production by the SRF, which had antifungal and growth promoting
properties, or an inhibition of growth of the fungus. Streptomycete A63 which stimulated the exudate production by the SRF
in vitro, however, did not enhance disease protection in vivo. On the other hand, protection from root rot by the SRF in vivo
was reduced in the presence of the streptomycete isolate Ax which is capable of inhibiting the growth of the SRF in vitro. 相似文献
128.
Antonio C. L. da Costa Lucy Rowland Rafael S. Oliveira Alex A. R. Oliveira Oliver J. Binks Yann Salmon Steel S. Vasconcelos João A. S. Junior Leandro V. Ferreira Rafael Poyatos Maurizio Mencuccini Patrick Meir 《Global Change Biology》2018,24(1):249-258
Transpiration from the Amazon rainforest generates an essential water source at a global and local scale. However, changes in rainforest function with climate change can disrupt this process, causing significant reductions in precipitation across Amazonia, and potentially at a global scale. We report the only study of forest transpiration following a long‐term (>10 year) experimental drought treatment in Amazonian forest. After 15 years of receiving half the normal rainfall, drought‐related tree mortality caused total forest transpiration to decrease by 30%. However, the surviving droughted trees maintained or increased transpiration because of reduced competition for water and increased light availability, which is consistent with increased growth rates. Consequently, the amount of water supplied as rainfall reaching the soil and directly recycled as transpiration increased to 100%. This value was 25% greater than for adjacent nondroughted forest. If these drought conditions were accompanied by a modest increase in temperature (e.g., 1.5°C), water demand would exceed supply, making the forest more prone to increased tree mortality. 相似文献
129.
Heterogeneity in host susceptibility and transmissibility to parasite attack allows a lower transmission rate to sustain an epidemic than is required in homogeneous host populations. However, this heterogeneity can leave some hosts with little susceptibility to disease, and at high transmission rates, epidemic size can be smaller than for diseases where the host population is homogeneous. In a heterogeneous host population, we model natural selection in a parasite population where host heterogeneity is exploited by different strains to varying degrees. This partitioning of the host population allows coexistence of competing parasite strains, with the heterogeneity-exploiting strains infecting the more susceptible hosts, in the absence of physiological tradeoffs and spatial heterogeneity, and even for markedly different transmission rates. In our model, intermediate-strategy parasites were selected against: should coexistence occur, an equilibrium is reached where strains occupied only the extreme ends of trait space, under appropriate conditions selecting for lower R0 . 相似文献
130.
Comparison of Cultures from Rectoanal-Junction Mucosal Swabs and Feces for Detection of Escherichia coli O157 in Dairy Heifers
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Margaret A. Davis Daniel H. Rice Haiqing Sheng Dale D. Hancock Thomas E. Besser Rowland Cobbold Carolyn J. Hovde 《Applied microbiology》2006,72(5):3766-3770
Fecal culture for Escherichia coli O157:H7 was compared to rectoanal mucosal swab (RAMS) culture in dairy heifers over a 1-year period. RAMS enrichment culture was as sensitive as fecal culture using immunomagnetic separation (IMS) (P = 0.98, as determined by a chi-square test). RAMS culture is less costly than fecal IMS culture and can yield quantitative data. 相似文献