全文获取类型
收费全文 | 714篇 |
免费 | 41篇 |
国内免费 | 2篇 |
学科分类
工业技术 | 757篇 |
出版年
2023年 | 5篇 |
2022年 | 5篇 |
2021年 | 21篇 |
2020年 | 13篇 |
2019年 | 16篇 |
2018年 | 13篇 |
2017年 | 9篇 |
2016年 | 20篇 |
2015年 | 18篇 |
2014年 | 29篇 |
2013年 | 43篇 |
2012年 | 35篇 |
2011年 | 38篇 |
2010年 | 29篇 |
2009年 | 28篇 |
2008年 | 29篇 |
2007年 | 36篇 |
2006年 | 27篇 |
2005年 | 23篇 |
2004年 | 21篇 |
2003年 | 20篇 |
2002年 | 21篇 |
2001年 | 13篇 |
2000年 | 6篇 |
1999年 | 10篇 |
1998年 | 9篇 |
1997年 | 12篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 11篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1974年 | 10篇 |
1973年 | 5篇 |
1971年 | 3篇 |
排序方式: 共有757条查询结果,搜索用时 15 毫秒
11.
12.
Alexandra C. K?lbl Udo Jeschke Ulrich Andergassen 《International journal of molecular sciences》2016,17(8)
Epithelial to mesenchymal transition (EMT) is a process involved in embryonic development, but it also plays a role in remote metastasis formation in tumor diseases. During this process cells lose their epithelial features and adopt characteristics of mesenchymal cells. Thereby single tumor cells, which dissolve from the primary tumor, are enabled to invade the blood vessels and travel throughout the body as so called “circulating tumor cells” (CTCs). After leaving the blood stream the reverse process of EMT, the mesenchymal to epithelial transition (MET) helps the cells to seed in different tissues, thereby generating the bud of metastasis formation. As metastasis is the main reason for tumor-associated death, CTCs and the EMT process are in the focus of research in recent years. This review summarizes what was already found out about the molecular mechanisms driving EMT, the consequences of EMT for tumor cell detection, and suitable markers for the detection of CTCs which underwent EMT. The research work done in this field could open new roads towards combating cancer. 相似文献
13.
14.
15.
16.
L. T. Phong J. J. Stoorvogel M. E. F. van Mensvoort H. M. J. Udo 《Nutrient Cycling in Agroecosystems》2011,90(1):33-49
This study quantifies soil nutrient balances of Integrated Agriculture-Aquaculture Systems in the Mekong Delta of Vietnam.
Eleven farms were monitored to collect data on farm activities and nutrient inputs and outputs to compute these balances of
the rice-based and high input fish system in O Mon district (R-HF); the rice-based and medium input fish system in Tam Binh
district (R-MF); and the orchard-based and low input fish system in Cai Be district (O-LF). For the estimation, the Nutmon
model has been adapted to the specific conditions in these integrated systems in Asia (Nutmon-Asia). New regression models
of leaching and gaseous losses of nitrogen were applied to fields used for upland crops and paddy rice. Reference values were
used for the assessment of nitrogen fixation in paddy soils, wet atmospheric deposition, and irrigation water. The results
showed that farms in all three systems have nitrogen, phosphorus and potassium surpluses (84 kg N, 73 kg P, and 69 kg K ha−1 year−1). The O-LF system had the smallest nitrogen surplus while the smallest surplus of phosphorus and potassium was seen in the
R-HF system. High surpluses of phosphorus and potassium were found in vegetable fields, whereas a negative potassium balance
was found in the rice fields of all three systems. The positive farm nutrient balances indicate that it is likely that soil
fertility will be maintained although there is a risk for environmental contamination. 相似文献
17.
Hae‐Ryong Kim Alexander Haensch Il‐Doo Kim Nicolae Barsan Udo Weimar Jong‐Heun Lee 《Advanced functional materials》2011,21(23):4402-4402
18.
19.
Cover Picture: Selective Inhibitors of the Protein Tyrosine Phosphatase SHP2 Block Cellular Motility and Growth of Cancer Cells in vitro and in vivo (ChemMedChem 5/2015) 下载免费PDF全文
20.
Hans-Juergen Odenthal Uwe Thiedemann Udo Falkenreck Jochen Schlueter 《Metallurgical and Materials Transactions B》2010,41(2):396-413
The oscillation of argon oxygen decarburization (AOD) converters is flow related and depends on the process parameters (e.g., vessel geometry, melt fill height, process gas type and blowing rate, vessel tilting angle, as well as geometry, number,
and arrangement of the side-wall nozzles). For a 120-ton AOD converter with seven submerged side-wall nozzles, plant tests,
physical simulations on a 1:4 scale water model, and computational fluid dynamics simulations have been done. The investigations
show that the penetration depth of an inert gas jet into the melt does not exceed approximately 0.4 m. The plumes are located
close to the nozzle-side converter wall and induce a large-scale primary vortex as well as intensive surface movements; both
are responsible for the oscillation. Several process mechanisms were investigated. The oscillation is highest in the last
stage of the dynamic blow and is still high during the reduction stage. As the amount of inert gas increases, the vibration
level also increases. Inert gas has a greater influence on the oscillation than oxygen. Tilting the converter around 8 deg
clearly leads to more intensive oscillations. Increasing the blowing rate increases the forces and torques acting on the vessel,
whereas the oscillation frequency remains nearly constant. A varying fill level does not influence the vibration level the
same way as the blowing rate. The operational test shows, for example, that the maximum torque does not depend on the heat
size when the latter varies between –8 pct and +21 pct of the nominal heat size. The water model test shows decreasing forces
and torques with a rising fill level. 相似文献