全文获取类型
收费全文 | 539篇 |
免费 | 29篇 |
专业分类
568篇 |
出版年
2022年 | 3篇 |
2020年 | 3篇 |
2019年 | 9篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 14篇 |
2015年 | 26篇 |
2014年 | 28篇 |
2013年 | 31篇 |
2012年 | 40篇 |
2011年 | 29篇 |
2010年 | 22篇 |
2009年 | 28篇 |
2008年 | 20篇 |
2007年 | 25篇 |
2006年 | 28篇 |
2005年 | 24篇 |
2004年 | 27篇 |
2003年 | 22篇 |
2002年 | 16篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 3篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 3篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1976年 | 3篇 |
1973年 | 3篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1958年 | 2篇 |
1938年 | 2篇 |
排序方式: 共有568条查询结果,搜索用时 15 毫秒
561.
562.
Maria Berndtsson Emma Hernlund Maria C. Shoshan Stig Linder 《Journal of chemical biology》2009,2(2):81-87
The phosphatidylinositol 3-kinase (PI3K)/AKT pathway is frequently upregulated in human cancer. Activation of this pathway
has been reported to be associated with resistance to various chemotherapeutical agents. We here used a chemical biology/chemical
informatic approach to identify apoptotic mechanisms that are insensitive to activation of the PI3K/AKT pathway. The National
Cancer Institute (NCI) Mechanistic Set drug library was screened for agents that induce apoptosis in colon carcinoma cells
expressing a constitutively active form of AKT1. The cytotoxicity screening data available as self-organized maps at the Developmental
Therapeutics Program (DTP) of the NCI was then used to classify the identified compounds according to mechanism of action.
The results showed that drugs that interfere with the mitotic process induce apoptosis which is comparatively insensitive
to constitutive AKT1 activity. The conditional screening approach described here is expected to be useful for identifying
relationships between the state of activation of signaling pathways and sensitivity to anticancer agents. 相似文献
563.
Michael A Hanson Kurt A Brorson Antonio R Moreira Govind Rao 《Microbial cell factories》2009,8(1):44-7
Background
Upstream bioprocesses are extremely complex since living organisms are used to generate active pharmaceutical ingredients (APIs). Cells in culture behave uniquely in response to their environment, thus culture conditions must be precisely defined and controlled in order for productivity and product quality to be reproducible. Thus, development culturing platforms are needed where many experiments can be carried out at once and pertinent scale-up information can be obtained. 相似文献564.
565.
566.
The effect of changed O2 - and CO2 -concentrations in air on oscillations in the transpiration rate of young oat plants in darkness has been investigated. Lowering the O2 -concentration to 5% did not affect the oscillations. When the CO2 in the air was removed, the transpiration rate increased, and the oscillations ceased. When the CO2 -concentration was raised to 0.3 or 3% the transpiration rate temporarily decreased, but the period of the oscillations was not changed. Further increase of the CO2 -concentration caused, after a temporary decrease, an increased transpiration rate, and the oscillations eventually ceased. The period of the oscillations was influenced by the temperature: a lower temperature gave a longer period. It is concluded that substomatal O2 -deficit or high CO2 -concentration do not play a crucial role in the origin of these oscillations. 相似文献
567.
568.
Sverre-Henning Brorson 《Biotechnic & histochemistry》1999,74(5):248-260
We examined the increase in immunogold labeling of variably fixed, resin embedded tissue sections following antigen retrieval by heating in citrate solution. Fibrin clots and porcine renal tissue were fixed in glutaraldehyde, paraformaldehyde or ethanol, and specimens were embedded in LR-White or epoxy resin. Immunogold labeling was performed on ultra-thin sections with anti-fibrinogen for the fibrin clots and anti-IgG for the porcine renal tissue. Immunogold labeling increased greatly after heating epoxy sections regardless of the fixative used. The ratio labelingretrieved/labelingnonretrieved (Lr/Ln) was 2.8 or higher, and the largest increases were obtained for anti-IgG. Heating induced a large increase of immunolabeling for LR-White sections only when the specimens had been fixed in paraformaldehyde (Lr/Ln = 2.2 for anti-IgG and 1.4 for antifibrinogen). LR-White sections showed decreased, insignificant or weakly increased immunolabeling of ethanol or glutaraldehyde fixed tissues following antigen retrieval. Disruption of aldehyde cross-links is not the only mechanism for antigen retrieval when epoxy sections are heated in citrate solution since large increases in immunolabeling were obtained on ethanol fixed tissue. The large heat-induced increases in immunolabeling on epoxy sections are probably caused by the disruption of chemical bonds between the epoxy resin and side groups of proteins. 相似文献