全文获取类型
收费全文 | 2549篇 |
免费 | 145篇 |
出版年
2023年 | 21篇 |
2022年 | 33篇 |
2021年 | 54篇 |
2020年 | 35篇 |
2019年 | 53篇 |
2018年 | 89篇 |
2017年 | 89篇 |
2016年 | 122篇 |
2015年 | 146篇 |
2014年 | 132篇 |
2013年 | 203篇 |
2012年 | 211篇 |
2011年 | 211篇 |
2010年 | 138篇 |
2009年 | 100篇 |
2008年 | 148篇 |
2007年 | 140篇 |
2006年 | 155篇 |
2005年 | 125篇 |
2004年 | 101篇 |
2003年 | 90篇 |
2002年 | 89篇 |
2001年 | 11篇 |
2000年 | 4篇 |
1999年 | 10篇 |
1998年 | 17篇 |
1997年 | 14篇 |
1996年 | 10篇 |
1995年 | 9篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1969年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有2694条查询结果,搜索用时 31 毫秒
61.
Piotr Bursztyka Dominique Saffray Céline Lafont-Lecuelle Antoine Brin Patrick Pageat 《PloS one》2013,8(11)
Evidence that terrestrial gastropods are able to detect chemical cues from their predators is obvious yet scarce, despite the scientific relevance of the topic to enhancing our knowledge in this area. This study examines the influence of cuticular extracts from predacious ground beetles (Carabus auratus, Carabus hispanus, Carabus nemoralis and Carabus coriaceus), and a neutral insect species (Musca domestica) on the shelter-seeking behavior of naive slugs (Deroceras reticulatum). Slugs, known to have a negative phototactic response, were exposed to light, prompting them to make a choice between either a shelter treated with a cuticular extract or a control shelter treated with pure ethyl alcohol. Their behavioral responses were recorded for one hour in order to determine their first shelter choice, their final position, and to compare the percentage of time spent in the control shelters with the time spent in the treated shelters.The test proved to be very effective: slugs spent most of the experiment in a shelter. They spent significantly more time in the control shelter than in the shelter treated with either C. nemoralis (Z = 2.43; p = 0.0151; Wilcoxon matched-pairs signed-ranks test) or C. coriaceus cuticular extracts (Z = 3.31; p<0.01; Wilcoxon matched-pairs signed-ranks test), with a seemingly stronger avoidance effect when presented with C. coriaceus extracts. The other cuticular extracts had no significant effect on any of the behavioral items measured. Although it cannot be entirely excluded that the differences observed, are partly due to the intrinsic properties of the vehicle employed to build the cuticular extracts, the results suggest that slugs can innately discriminate amongst different potential predators and adjust their behavioral response according to the relevance of the threat conveyed by their predator’s chemical cues. 相似文献
62.
Muszyńska Bożena Kała Katarzyna Włodarczyk Anna Krakowska Agata Ostachowicz Beata Gdula-Argasińska Joanna Suchocki Piotr 《Biological trace element research》2020,194(2):614-615
Biological Trace Element Research - The original version of this article unfortunately contained a mistake. 相似文献
63.
Wenjing Li Piotr Łączyński Hermes E. Escalona Jonas Eberle Lizhi Huo Xiaosheng Chen Weidong Huang Bingxu Chen Dirk Ahrens Adam Ślipiński Wioletta Tomaszewska Xingmin Wang 《Systematic Entomology》2020,45(2):447-463
Ladybirds of the cosmopolitan tribe Chilocorini prey mainly on coccids and include several important biocontrol agents. The phylogenetic relationships of Chilocorini are poorly known. In this paper, we provide a phylogenetic reconstruction of Chilocorini containing all 27 genera based on five molecular markers and 86 adult morphological characters. Morphological character states were mapped on the combined data tree from Bayesian inference to analyse morphological traits of each genus. Sixteen morphological characters were selected to reconstruct the ancestral states using maximum parsimony and maximum likelihood methods. Divergence times were estimated based on the relaxed molecular clock approach. Our results indicate that Chilocorini, excluding Chilocorellus Miyatake, is monophyletic and closely related to Plotinini. The crown group Chilocorini was estimated to date back to the Middle Cretaceous. Anisorcus Crotch, Egius Mulsant, Phaenochilus Weise and Simmondsius Ahmad & Ghani are synonymized here with Chilocorus Leach ( syn.n. ). The genus Chilocorellus is excluded from Chilocorini. The split of current genera was estimated to have occurred during the Middle Paleogene to Late Paleogene. 相似文献
64.
Dorota Dziadkowiec Karol Kramarz Karolina Kanik Piotr Wi?niewski Antony M. Carr 《Nucleic acids research》2013,41(17):8196-8209
Previously we identified Rrp1 and Rrp2 as two proteins required for the Sfr1/Swi5-dependent branch of homologous recombination (HR) in Schizosaccharomyces pombe. Here we use a yeast two-hybrid approach to demonstrate that Rrp1 and Rrp2 can interact with each other and with Swi5, an HR mediator protein. Rrp1 and Rrp2 form co-localizing methyl methanesulphonate–induced foci in nuclei, further suggesting they function as a complex. To place the Rrp1/2 proteins more accurately within HR sub-pathways, we carried out extensive epistasis analysis between mutants defining Rrp1/2, Rad51 (recombinase), Swi5 and Rad57 (HR-mediators) plus the anti-recombinogenic helicases Srs2 and Rqh1. We confirm that Rrp1 and Rrp2 act together with Srs2 and Swi5 and independently of Rad57 and show that Rqh1 also acts independently of Rrp1/2. Mutants devoid of Srs2 are characterized by elevated recombination frequency with a concomitant increase in the percentage of conversion-type recombinants. Strains devoid of Rrp1 or Rrp2 did not show a change in HR frequency, but the number of conversion-type recombinants was increased, suggesting a possible function for Rrp1/2 with Srs2 in counteracting Rad51 activity. Our data allow us to propose a model placing Rrp1 and Rrp2 functioning together with Swi5 and Srs2 in a synthesis-dependent strand annealing HR repair pathway. 相似文献
65.
Attachment of Brachyspira hyodysenteriae to intestinal epithelial cell lines and its possible mediation by outer membrane proteins (OMPs) of the spirochete were examined. Different B. hyodysenteriae serotypes were shown to adhere to rat and swine intestinal epithelial cells (IEC-18 and IPEC-J2) in vitro but not to the human rectal tumor cell line (HRT-18). Adherence of strain B204 to IPEC-J2 cells was reduced by rOMP-specific antisera in amounts of 29 % (anti-rBhlp29.7), 59 % (anti-rBhlp16), 70 % (anti-rBhmp39h), and 74 % (anti-rBhmp39h), respectively. By use of pooled antisera against Bhlp16 and Bhmp39f inhibition rates of the other serotypes ranged from 53 to 91 %. In a western blot assay OMPs of all serotypes but one were detected by the respective rOMP antisera. Altogether the results indicated that OMPs of B. hyodysenteriae displayed a serotype overlapping antigenicity and mediated adherence of the spirochetes to animal cell cultures. 相似文献
66.
Ole J Hamming Ewa Terczyńska‐Dyla Gabrielle Vieyres Ronald Dijkman Sanne E Jørgensen Hashaam Akhtar Piotr Siupka Thomas Pietschmann Volker Thiel Rune Hartmann 《The EMBO journal》2013,32(23):3055-3065
The IFNL4 gene is a recently discovered type III interferon, which in a significant fraction of the human population harbours a frameshift mutation abolishing the IFNλ4 ORF. The expression of IFNλ4 is correlated with both poor spontaneous clearance of hepatitis C virus (HCV) and poor response to treatment with type I interferon. Here, we show that the IFNL4 gene encodes an active type III interferon, named IFNλ4, which signals through the IFNλR1 and IL‐10R2 receptor chains. Recombinant IFNλ4 is antiviral against both HCV and coronaviruses at levels comparable to IFNλ3. However, the secretion of IFNλ4 is impaired compared to that of IFNλ3, and this impairment is not due to a weak signal peptide, which was previously believed. We found that IFNλ4 gets N‐linked glycosylated and that this glycosylation is required for secretion. Nevertheless, this glycosylation is not required for activity. Together, these findings result in the paradox that IFNλ4 is strongly antiviral but a disadvantage during HCV infection. 相似文献
67.
Magdalena K?dzierska Rafa? G?owacki Urszula Czernek Katarzyna Szyd?owska-Pazera Piotr Potemski Janusz Piekarski Arkadiusz Jeziorski Beata Olas 《Molecular and cellular biochemistry》2013,372(1-2):47-55
Different low-molecular-weight thiols, including glutathione, cysteine, and cysteinylglycine are physiological free radical scavengers. On the other hand, homocysteine may play a role as an oxidant. The aim of our present study was to establish in vitro the effects of the commercial extract of Aronia melanocarpa (Aronox?) on the amount of selected low-molecular-weight thiols and the activity of antioxidative enzymes (superoxide dismutase, glutathione peroxidase, and glutathione reductase) in plasma obtained from patients with invasive breast cancer during different phases of treatment [before or after the surgery and patients after different phases of chemotherapy (doxorubicin and cyclophosphamide)] and from healthy subjects. Patients were hospitalized in Department of Oncological Surgery and Department of Chemotherapy, Medical University of Lodz, Poland. The level of low-molecular-weight thiols was determined by high-performance liquid chromatography. We observed that in the presence of the Aronia extract changes in amount of thiols in plasma from breast cancer patients (at all tested groups) were significantly reduced. Our results showed that tested commercial extract reduced modifications of antioxidative enzymes activity in plasma from patients during different phases of treatment, but this effect was not statistical significant. Our results suggest that the Aronia extract supplementation in breast cancer patients has a beneficial effect on thiols concentration in plasma. Plasma, as reported in this work, could be used as an experimental model to evaluate the beneficial action of plant supplements, including phenolic extracts on thiols or other molecules during different phases of treatment. 相似文献
68.
Krzysztof Mędrek Piotr Magnowski Bartłomiej Masojć Anita Chudecka-Głaz Bogdan Torbe Janusz Menkiszak Marek Spaczyński Jacek Gronwald Jan Lubiński Bohdan Górski 《Molecular biology reports》2013,40(3):2145-2147
Among many alterations within the TP53 gene the rs1042522 (C72G, p.Pro72Arg) has been associated with numerous cancers , however the results differ between populations for opposite Pro or Arg alleles. Similar thus inconclusive results are observed in ovarian cancer, which may suggest that the rs1042522 does not influence ovarian carcinogensis directly, but might be linked to another pathogenic alteration. WRAP53 which overlaps the TP53 is required to maintain normal levels of p53 upon DNA damage, but also when altered may independently increase the risk of cancer. To evaluate the association between three SNPs located in WRAP53–TP53 region: rs1042522, rs2287497, rs2287498 and ovarian cancer risk in Polish population we genotyped 626 cases and 1,045 healthy controls. Our results provide the evidence for an association between studied SNPs and a risk of invasive ovarian cancer in Poland. We found that CC homozygotes in rs1042522 were more frequent in cancers when compared to controls (OR = 1.46, p = 0.03). Similarly in WRAP53 both TT homozygotes in rs2287497 (OR = 1.95, p = 0.03) and AA homozygotes in rs2287498 (OR = 2.65, p = 0,01) were more frequent among cases than healthy individuals. There is also a suggestive evidence that specific homozygosity of studied SNPs in TP53–WRAP53 region is significantly overrepresented in ovarian cancer patients. In conclusion SNPs in WRAP53 (rs2287497 and rs2287498) have stronger association with an ovarian cancer risk than rs1042522 in TP53. 相似文献
69.
70.
The predator satiation hypothesis states that synchronous periodic production of seeds is an adaptive strategy evolved to reduce the pressure of seed predators. The seed production pattern is crucial to the predator satiation hypothesis, but there are few studies documenting the success of individuals that are in synchrony and out of synchrony with the whole population. This study is based on long-term data on seed production of Sorbus aucuparia and specialised pre-dispersal seed predation by Argyresthia conjugella, in a subalpine spruce forest in the Western Carpathians (Poland). At the population level, we tested whether functional and numerical responses of predators to the variation of fruit production operate. At the individual level, we tested whether individuals with higher interannual variability in their own seed crops and higher synchrony with the population have higher percentages of uninfested fruits. The intensity of pre-dispersal seed predation was high (average 70 %; range 19–100 %). There were both functional and numerical responses of predators to the variation of fruit production at the population level. We found that individuals that were expected to be preferred under seed predator pressure had higher reproductive success. With increasing synchrony of fruit production between individual trees and the population, the percentage of infested fruits decreased. There was also a negative relationship between the interannual variation in individual fruit production and the percentage of infested fruits. These results confirm selection for individuals with a masting strategy. However, the population does not seem well adapted to strong seed predation pressure and we suggest that this may be a result of prolonged diapause of A. conjugella. 相似文献