全文获取类型
收费全文 | 757篇 |
免费 | 71篇 |
出版年
2023年 | 7篇 |
2022年 | 2篇 |
2021年 | 23篇 |
2020年 | 12篇 |
2019年 | 7篇 |
2018年 | 23篇 |
2017年 | 15篇 |
2016年 | 31篇 |
2015年 | 56篇 |
2014年 | 67篇 |
2013年 | 69篇 |
2012年 | 83篇 |
2011年 | 71篇 |
2010年 | 48篇 |
2009年 | 35篇 |
2008年 | 50篇 |
2007年 | 49篇 |
2006年 | 40篇 |
2005年 | 39篇 |
2004年 | 25篇 |
2003年 | 29篇 |
2002年 | 19篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1989年 | 1篇 |
排序方式: 共有828条查询结果,搜索用时 15 毫秒
801.
Sebastian C. A. Ferse Maggy M. Nugues Sascha B. C. Romatzki Andreas Kunzmann 《Restoration Ecology》2013,21(6):745-754
Coral transplantation is frequently advocated as a possible means of coral reef rehabilitation. One of the purported benefits of transplantation is a positive effect of transplants on coral recruitment by sexual reproduction of transplants (“seeding”) and/or settlement cues generated by the presence of live coral (“attraction”). However, evidence for this assertion is scarce. Here, we investigated the effect of coral transplantation on larval recruitment. A total of 6,164 fragments of four coral species (acroporids and pocilloporids) were transplanted at three sites in North Sulawesi, Indonesia. Coral recruitment onto limestone settlement plates was examined every 3 months and on concrete structures at the end of the study (≥15 months) in the presence and absence of transplants. Transplant survival after 1 year ranged between 20 and 30% for pocilloporids and between 40 and 80% for acroporids. Transplantation had no consistent effect on the number of coral recruits on the settlement plates or on the concrete structures. Recruitment was relatively high compared to other locations in the region and fluctuated seasonally, with increased rates in all treatments during peaks of reproduction. We conclude that, in the presence of high background recruitment and detrimental environmental conditions, coral transplantation may not be an effective method to boost coral recruitment. The provision of stable substrate for settlement in the form of artificial reefs, combined with improved management to reduce chronic stressors, constitutes a better use of resources. 相似文献
802.
C. Renner Gerhard Held Sascha Ohnesorge Stefan Bauer Klaus Gerlach Jan-Peter Pfitzenmeier Michael Pfreundschuh 《Cancer immunology, immunotherapy : CII》1997,44(2):70-76
Bispecific monoclonal antibodies (bi-mAb), directed against a tumor-associated antigen and the CD3 or CD28 antigen on T lymphocytes,
induce activation of resting T lymphocytes and target-specific tumor cell lysis. We now show that both necrosis and apoptosis
contribute to T-cell-mediated tumor cell destruction. Even though T cells up-regulate FAS/APO-1 expression upon bi-mAb stimulation,
FAS/APO-1-mediated apoptosis does not contribute to bi-mAb-mediated destruction of Hodgkin’s cells. CD8+ lymphocytes were the most potent effectors of bi-mAb-mediated cytotoxicity and had the highest levels of mRNA coding for
perforin and granzyme A and B. Ca2+-complexing agents, which abrogate perforin activity, led to decreased levels of necrosis, while inhibition of granzyme activity
in effector or target cells had a similar effect on apoptosis. Granzyme-mediated apoptosis critically dependent on the proliferative
state of the target cells, while perforin-induced necrosis was not cell-cycle-dependent. Our results underline the importance
of the expression levels of perforin and granzymes in the effector T cells and of the proliferative state of the target cells
in bi-mAb-mediated apoptosis and necrosis of tumor cells.
Received: 5 December 1996 / Accepted: 16 January 1997 相似文献
803.
LNX functions as a RING type E3 ubiquitin ligase that targets the cell fate determinant Numb for ubiquitin-dependent degradation. 下载免费PDF全文
Jing Nie Melanie A McGill Matt Dermer Sascha E Dho Cheryl D Wolting C Jane McGlade 《The EMBO journal》2002,21(1-2):93-102
LNX is a RING finger and PDZ domain containing protein that interacts with the cell fate determinant Numb. To investigate the function of LNX, we tested its RING finger domain for ubiquitin ligase activity. The isolated RING finger domain was able to function as an E2-dependent, E3 ubiquitin ligase in vitro and mutation of a conserved cysteine residue within the RING domain abolished its activity, indicating that LNX is the first described PDZ domain-containing member of the E3 ubiquitin ligase family. We have identified Numb as a substrate of LNX E3 activity in vitro and in vivo. In addition to the RING finger, a region of LNX, including the Numb PTB domain-binding site and the first PDZ domain, is required for Numb ubiquitylation. Expression of wild-type but not mutant LNX causes proteasome-dependent degradation of Numb and can enhance Notch signalling. These results suggest that the levels of mammalian Numb protein and therefore, by extension, the processes of asymmetric cell division and cell fate determination may be regulated by ubiquitin-dependent proteolysis. 相似文献
804.
805.
Sascha Fuller 《The Australian journal of anthropology》2020,31(2):240-256
In a small Bahun village in Gorkha district, West Nepal, in only one generation, there has been a huge shift to educating young women and including them in modernity. Ideologies of ‘gender equality’ in education that are promoted in development programs and discourse, and in Maoist rhetoric, have been powerful drivers behind this. In this paper I highlight the gender and generational dynamics of the changing relationship of women to education in Nepal. I argue that the move to educating women is not a simple one, nor is it necessarily a development success story. The importance placed on educating the younger generation, including women, is also very much tied to local Bahun culture, marriage values and status. Bahun villagers of Ludigaun place great importance on both education and marriage. When combined, I argue, education has in fact become dowry. While there have been transformations in education and other modernising processes, as well as in dowry practices, in this paper I show that they have come to maintain traditional hierarchies and to support the status making of the educated Bahun man. 相似文献
806.
Sascha R?sner Kirsten Bogatz Hendrik Trapp Thomas Grünkorn Roland Brandl 《Journal of Ornithology》2009,150(1):293-297
Many bird species adjust their offspring sex ratio as a response to environmental conditions or sexual dimorphism in size
and dispersal. Offspring sex ratios may therefore vary among populations depending on the different demographic and ecological
trajectories. We sampled Common Raven Corvus corax nestlings close to the fledging stage from three Central European regions to test for skewed secondary sex ratios and to
investigate differences in sex ratios between populations that differ in recent recolonization history and breeding densities.
Between 2005 and 2007, a total of 108 broods with 335 nestlings were sampled and their sex determined using molecular methods.
We observed a mean of 3.1 (±1.2) nestlings per brood with no differences among nesting sites, years or regions. Nestling sex
ratios were independent of the number of siblings. The overall secondary sex ratio was close to parity and did not differ
between the variably structured populations. 相似文献
807.
808.
Nga Nguyen Peter J. Fashing Derek A. Boyd Tyler S. Barry Ryan J. Burke C. Barret Goodale Sorrel C.Z. Jones Jeffrey T. Kerby Bryce S. Kellogg Laura M. Lee Carrie M. Miller Niina O. Nurmi Malcolm S. Ramsay Jason D. Reynolds Kathrine M. Stewart Taylor J. Turner Vivek V. Venkataraman Yvonne Knauf Christian Roos Sascha Knauf 《American journal of primatology》2015,77(5):579-594
809.
810.
Schreiber Sarah Thiefes Axel Schuldt Ute Dähne Lars Scheper Thomas Beutel Sascha 《Applied microbiology and biotechnology》2017,101(2):599-607
Applied Microbiology and Biotechnology - The objective of this study was to use for the first time depth filters, which are usually intended for clarification of cell culture broth, as a direct... 相似文献