全文获取类型
收费全文 | 20390篇 |
免费 | 1898篇 |
国内免费 | 12篇 |
出版年
2023年 | 121篇 |
2022年 | 301篇 |
2021年 | 563篇 |
2020年 | 268篇 |
2019年 | 388篇 |
2018年 | 436篇 |
2017年 | 340篇 |
2016年 | 586篇 |
2015年 | 985篇 |
2014年 | 1020篇 |
2013年 | 1399篇 |
2012年 | 1598篇 |
2011年 | 1565篇 |
2010年 | 967篇 |
2009年 | 844篇 |
2008年 | 1213篇 |
2007年 | 1192篇 |
2006年 | 1074篇 |
2005年 | 1016篇 |
2004年 | 914篇 |
2003年 | 852篇 |
2002年 | 824篇 |
2001年 | 197篇 |
2000年 | 153篇 |
1999年 | 178篇 |
1998年 | 168篇 |
1997年 | 141篇 |
1996年 | 117篇 |
1995年 | 110篇 |
1994年 | 117篇 |
1993年 | 112篇 |
1992年 | 119篇 |
1991年 | 107篇 |
1990年 | 97篇 |
1989年 | 85篇 |
1988年 | 92篇 |
1987年 | 72篇 |
1986年 | 66篇 |
1985年 | 89篇 |
1984年 | 96篇 |
1983年 | 62篇 |
1982年 | 81篇 |
1981年 | 72篇 |
1980年 | 67篇 |
1979年 | 77篇 |
1978年 | 54篇 |
1977年 | 60篇 |
1976年 | 65篇 |
1975年 | 70篇 |
1973年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
831.
Mazanko Maria S. Makarenko Maksim S. Chistyakov Vladimir A. Usatov Alexander V. Prazdnova Evgeniya V. Bren Anzhelika B. Gorlov Ivan F. Komarova Zoya B. Weeks Richard Chikindas Michael L. 《Probiotics and antimicrobial proteins》2019,11(4):1324-1329
Probiotics and Antimicrobial Proteins - A promising approach for slowing down the rate of reproductive aging is the use of probiotic bacteria as a feed additive. In the current study was... 相似文献
832.
Total internal reflection fluorescence excitation (TIRF) microscopy allows the selective observation of fluorescent molecules in immediate proximity to an interface between different refractive indices. Objective‐type or prism‐less TIRF excitation is typically achieved with laser light sources. We here propose a simple, yet optically advantageous light‐emitting diode (LED)‐based implementation of objective‐type TIRF (LED‐TIRF). The proposed LED‐TIRF condenser is affordable and easy to set up at any epifluorescence microscope to perform multicolor TIRF and/or combined TIRF‐epifluorescence imaging with even illumination of the entire field of view. Electrical control of LED light sources replaces mechanical shutters or optical modulators. LED‐TIRF microscopy eliminates safety burdens that are associated with laser sources, offers favorable instrument lifetime and stability without active cooling. The non‐coherent light source and the type of projection eliminate interference fringing and local scattering artifacts that are associated with conventional laser‐TIRF. Unlike azimuthal spinning laser‐TIRF, LED‐TIRF does not require synchronization between beam rotation and the camera and can be monitored with either global or rolling shutter cameras. Typical implementations, such as live cell multicolor imaging in TIRF and epifluorescence of imaging of short‐lived, localized translocation events of a Ca2+‐sensitive protein kinase C α fusion protein are demonstrated. 相似文献
833.
834.
835.
Sabrina C. Lachmann Tabea Mettler‐Altmann Alexander Wacker Elly Spijkerman 《Ecology and evolution》2019,9(3):1070-1082
In freshwaters, algal species are exposed to different inorganic nitrogen (Ni) sources whose incorporation varies in biochemical energy demand. We hypothesized that due to the lesser energy requirement of ammonium ()‐use, in contrast to nitrate ()‐use, more energy remains for other metabolic processes, especially under CO2‐ and phosphorus (Pi) limiting conditions. Therefore, we tested differences in cell characteristics of the green alga Chlamydomonas acidophila grown on or under covariation of CO2 and Pi‐supply in order to determine limitations, in a full‐factorial design. As expected, results revealed higher carbon fixation rates for ‐grown cells compared to growth with under low CO2 conditions. ‐grown cells accumulated more of the nine analyzed amino acids, especially under Pi‐limited conditions, compared to cells provided with . This is probably due to a slower protein synthesis in cells provided with . In contrast to our expectations, compared to ‐grown cells ‐grown cells had higher photosynthetic efficiency under Pi‐limitation. In conclusion, growth on the Ni‐source did not result in a clearly enhanced Ci‐assimilation, as it was highly dependent on Pi and CO2 conditions (replete or limited). Results are potentially connected to the fact that C. acidophila is able to use only CO2 as its inorganic carbon (Ci) source. 相似文献
836.
The leukocyte adhesion cascade is of critical importance for both the maintenance of immune homeostasis and the ability of immune cells to perform effector functions. Here, we present data showing CD4+ T cells migrate upstream (against the direction of flow) after completing the leukocyte adhesion cascade on surfaces displaying either ICAM-1 or ICAM-1 and VCAM-1, but migrate downstream on surfaces displaying only VCAM-1. Cells completing the cascade on HUVECs initially migrate upstream before reverting to more random migration, partly caused by transmigration of cells migrating against the flow. Furthermore, cells migrating upstream transmigrate faster than cells migrating downstream. On HUVECs, blocking interactions between LFA-1 and ICAM-1 resulted in downstream migration and slower transmigration. These results further suggest a possible physiological role for upstream migration in vivo. 相似文献
837.
838.
839.