全文获取类型
收费全文 | 3986篇 |
免费 | 252篇 |
国内免费 | 3篇 |
出版年
2023年 | 20篇 |
2022年 | 37篇 |
2021年 | 95篇 |
2020年 | 64篇 |
2019年 | 73篇 |
2018年 | 123篇 |
2017年 | 91篇 |
2016年 | 167篇 |
2015年 | 216篇 |
2014年 | 214篇 |
2013年 | 322篇 |
2012年 | 343篇 |
2011年 | 327篇 |
2010年 | 220篇 |
2009年 | 145篇 |
2008年 | 243篇 |
2007年 | 233篇 |
2006年 | 221篇 |
2005年 | 198篇 |
2004年 | 170篇 |
2003年 | 152篇 |
2002年 | 151篇 |
2001年 | 31篇 |
2000年 | 17篇 |
1999年 | 31篇 |
1998年 | 34篇 |
1997年 | 28篇 |
1996年 | 24篇 |
1995年 | 24篇 |
1994年 | 19篇 |
1993年 | 19篇 |
1992年 | 28篇 |
1991年 | 17篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1974年 | 4篇 |
排序方式: 共有4241条查询结果,搜索用时 15 毫秒
131.
Martin Parnov Reichhardt Hanna Jarva Anna Inkeri Lokki Hannele Laivuori FINNPEC study group Piia Vuorela Vuokko Loimaranta Andreas Glasner Monika Siwetz Berthold Huppertz Seppo Meri 《PloS one》2016,11(2)
Pre-eclampsia is a leading cause of maternal and perinatal morbidity and mortality worldwide. The etiology is not clear, but an immune attack towards components of placenta or fetus has been indicated. This involves activation of the complement system in the placenta. We have previously described the presence of the complement-regulating protein salivary scavenger and agglutinin (SALSA) in amniotic fluid. In this study we investigated the potential role of SALSA in pregnancy by analyzing its presence in amniotic fluid and placental tissue during healthy and complicated pregnancies. SALSA levels in amniotic fluid increased during pregnancy. Before 20 weeks of gestation the levels were slightly higher in patients who later developed pre-eclampsia than in gestation age-matched controls. In the placenta of pre-eclamptic patients syncytial damage is often followed by the formation of fibrinoid structures. SALSA was found clustered into these fibrinoid structures in partial co-localization with complement C1q and fibronectin. In vitro analysis showed direct protein binding of SALSA to fibronectin. SALSA binds also to fibrin/fibrinogen but did not interfere with the blood clotting process in vitro. Thus, in addition to antimicrobial defense and epithelial differentiation, the data presented here suggest that SALSA, together with fibronectin and C1q, may be involved in the containment of injured placental structures into fibrinoids. 相似文献
132.
Darren McMorran Dwayne Chung Kim Chung Monika Toth Oi Wah Liew Murat Muradoglu Tuck Wah Ng 《Analytical biochemistry》2016
During the collection phase of the dried blood spot method, practitioners need to ensure that there is no smearing of the blood sample on the filter paper or else readings from it will be invalid. This can be difficult to accomplish in the field if there is relative motion between the site of blood discharge on the finger and the filter paper. In this article, a gyroscope stabilization method is introduced and demonstrated to provide consistent and improved dried blood spot collection within a circular guide region notwithstanding the presence of rocking. 相似文献
133.
Szymańska-Chargot Monika Chylińska Monika Pieczywek Piotr M. Rösch Petra Schmitt Michael Popp Jürgen Zdunek Artur 《Planta》2016,243(4):935-945
Planta - Du ring on-tree ripening, the pectin distribution changed from polydispersed in cell wall to cumulated in cell wall corners. During apple storage, the pectin distribution returned to... 相似文献
134.
Monika Hassel 《当今生物学》2016,46(4):228-234
Axis formation in animals The last common ancestor of Cnidaria and Bilateria likely used the WNT/β‐Catenin pathway in a regionalized fashion to establish its primary, anterior‐posterior axis. Unexpectedly, the morphological head of Cnidaria corresponds to the rear end of Bilateria. Moreover, annelids use the WNT/β‐Catenin system for early, local and binary decisions, and insects developed a completely unrelated pathway. They use Bicoid (Drosophila) – or Hunchback/Orthodenticle (Tribolium) – to control axis formation. Nevertheless, WNT functions are essential during the segmentation phase in insects and in ancestral insects as well as in other arthropods during formation of posterior structures. In summary, the WNT/β‐Catenin system is an essential part of the molecular tool kit, which helped to establish the unique features of animals. 相似文献
135.
136.
137.
138.
The toxicity of the Aggregatibacter actinomycetemcomitans cytolethal distending toxin correlates with its phosphatidylinositol‐3,4,5‐triphosphate phosphatase activity
下载免费PDF全文
![点击此处可从《Cellular microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Bruce J. Shenker Kathleen Boesze‐Battaglia Monika Damek Scuron Lisa P Walker Ali Zekavat Mensur Dlakić 《Cellular microbiology》2016,18(2):223-243
The Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) induces G2 arrest and apoptosis in lymphocytes and other cell types. We have shown that the active subunit, CdtB, exhibits phosphatidylinositol‐3,4,5‐triphosphate (PIP3) phosphatase activity, leading us to propose that Cdt toxicity is the result of PIP3 depletion and perturbation of phosphatidylinositol‐3‐kinase (PI‐3K)/PIP3/Akt signalling. To further explore this relationship, we have focused our analysis on identifying residues that comprise the catalytic pocket and are critical to substrate binding rather than catalysis. In this context, we have generated several CdtB mutants and demonstrate that, in each instance, the ability of the toxin to induce cell cycle arrest correlates with retention of phosphatase activity. We have also assessed the effect of Cdt on downstream components of the PI‐3K signalling pathway. In addition to depletion of intracellular concentrations of PIP3, toxin‐treated lymphocytes exhibit decreases in pAkt and pGSK3β. Further analysis indicates that toxin‐treated cells exhibit a concomitant loss in Akt activity and increase in GSK3β kinase activity consistent with observed changes in their phosphorylation status. We demonstrate that cell susceptibility to Cdt is dependent upon dephosphorylation and concomitant activation of GSK3β. Finally, we demonstrate that, in addition to lymphocytes, HeLa cells exposed to a CdtB mutant that retains phosphatase activity and not DNase activity undergo G2 arrest in the absence of H2AX phosphorylation. Our results provide further insight into the mode of action by which Cdt may function as an immunotoxin and induce cell cycle arrest in target cells such as lymphocytes. 相似文献
139.
Mirosław Mleczek Paweł Rutkowski Przemysław Niedzielski Piotr Goliński Monika Gąsecka Tomisław Kozubik 《International journal of phytoremediation》2016,18(11):1086-1095
The aim of the study was to estimate the ability of ten tree and bush species to tolerate and accumulate Cd, Cu, Pb, Zn, and As species [As(III), As(V), and total organic arsenic] in industrial sewage sludge extremely contaminated with arsenic (almost 27.5 g kg?1) in a pot experiment. The premise being that it will then be possible to select the most promising tree/bush species, able to grow in the vicinity of dams where sewage sludge/flotation tailings are used as landfill. Six of the ten tested tree species were able to grow on the sludge. The highest content of total As was observed in Betula pendula roots (30.0 ± 1.3 mg kg?1 DW), where the dominant As species was the toxic As(V). The highest biomass of Quercus Q1 robur (77.3 § 2.6 g) and Acer platanoides (76.0 § 4.9 g) was observed. A proper planting of selected tree species that are able to thrive on sewage sludge/flotation tailings could be an interesting and promising way to protect dams. By utilizing differences in their root systems and water needs, we will be able to reduce the risk of fatal environmental disasters. 相似文献
140.
ADP-ribosylation is involved in a variety of biological processes, many of which are chromatin-dependent and linked to important functions during the cell cycle. However, any study on ADP-ribosylation and the cell cycle faces the problem that synchronization with chemical agents or by serum starvation and subsequent growth factor addition already activates ADP-ribosylation by itself. Here, we investigated the functional contribution of ARTD1 in cell cycle re-entry and G1/S cell cycle progression using T24 urinary bladder carcinoma cells, which synchronously re-enter the cell cycle after splitting without any additional stimuli. In synchronized cells, ARTD1 knockdown, but not inhibition of its enzymatic activity, caused specific down-regulation of cyclin E during cell cycle re-entry and G1/S progression through alterations of the chromatin composition and histone acetylation, but not of other E2F-1 target genes. Although Cdk2 formed a functional complex with the residual cyclin E, p27Kip1 protein levels increased in G1 upon ARTD1 knockdown most likely due to inappropriate cyclin E-Cdk2-induced phosphorylation-dependent degradation, leading to decelerated G1/S progression. These results provide evidence that ARTD1 regulates cell cycle re-entry and G1/S progression via cyclin E expression and p27Kip1 stability independently of its enzymatic activity, uncovering a novel cell cycle regulatory mechanism. 相似文献