全文获取类型
收费全文 | 359篇 |
免费 | 36篇 |
国内免费 | 2篇 |
出版年
2022年 | 5篇 |
2021年 | 6篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 12篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 11篇 |
2012年 | 14篇 |
2011年 | 20篇 |
2010年 | 11篇 |
2009年 | 5篇 |
2008年 | 17篇 |
2007年 | 18篇 |
2006年 | 20篇 |
2005年 | 15篇 |
2004年 | 13篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 11篇 |
2000年 | 26篇 |
1999年 | 7篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 10篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 5篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1966年 | 6篇 |
排序方式: 共有397条查询结果,搜索用时 15 毫秒
111.
We investigated the cytotoxic and apoptotic effects of a methanol extract of Centaurea nerimaniae, a plant endemic in Turkey, on HeLa and MDA-MB-231 cells. Eight concentrations of C. nerimaniae extract were applied to cells, and cytotoxic effects were measured using the xCELLigence system. The TUNEL assay was used to assess apoptotic cell death and immunohistochemistry was used to determine active caspase-3 using the effective cytotoxic doses of the extract. Doses of 1.42 mg/ml C. nerimaniae inhibited the growth of HeLa cells and 3.67 mg/ml C. nerimaniae inhibited the growth of MDA-MB-231 cells in a dose- and time-dependent manner. The apoptotic indexes for HeLa and MDA-MB-231 cells were increased significantly compared to control groups. Immunohistochemistry showed that the number of caspase-3 immunostained cells increased in the extract treatment groups for both HeLa and MDA-MB-231 cells. In the MDA-MB-231 cell line, caspase-3 immunostaining was observed in nuclei and/or cytoplasm in the extract treated group. Caspase-3 activation was greater in HeLa cells than in MDA-MB-231 cells. We found that the extract of C. nerimaniae had a strong antiproliferative effect and induced apoptosis via caspase-3; MDA-MB-231 cancer cells were more resistant than HeLa cells. 相似文献
112.
Change of calorigenic effect of noradrenaline after 5 week cold exposition (at 6-8 degrees C) as a criteria of specific adaptation was used. Individual differences of calorigenic reaction after cold exposition were negative correlation with blood corticosterone and positive correlation with aggressiveness in dyadic test. 相似文献
113.
Intraretinal variability and specialization of cones in Japanese anchovy (Engraulis japonicus,Engraulidae)
下载免费PDF全文
![点击此处可从《Journal of morphology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
S.L. Kondrashev M.S. Kornienko V.P. Gnyubkina L.T. Frolova 《Journal of morphology》2016,277(4):472-481
The retina of anchovies is characterized by an unusual arrangement and ultrastructure of cones. In the retina of Japanese anchovies, Engraulis japonicus, three types of cones are distributed into rows. The nasal, central, temporal, and ventro‐temporal regions of the retina were occupied exclusively by the long and short cones. Triple cones, made up of two lateral components and one smaller central component, were found only in the dorsal and ventro‐nasal retinal regions. In the outer segments of all short and long cones from the ventro‐temporal region, the lamellae were oriented along the cell axis and were perpendicular to the lamellae in the long cones, providing a morphological basis for the detection of polarization. This lamellar orientation is unique to all vertebrates. The cones were examined with respect to regional differentiation in their size and spectral properties via light microscopy, transmission electron microscopy, and microspectrophotometry. Various dimensions of cones were measured in preparations of isolated cells. The cones from the ventro‐temporal region had different dimensions than cones of the same type located in other retinal regions. Triple cones from the dorsal region were significantly larger than triple cones from the ventro‐nasal region. The spectral absorbance of the lateral components of triple cones in the ventro‐nasal retina was identical to the absorbance of all long and short cones from the ventro‐temporal region. These are shifted to shorter wavelengths relative to the absorbance of the lateral components of the triple cones located in the dorsal retina. Thus, the retina of the Japanese anchovy shows some features of regional specialization common in other fishes that improves spatial resolution for the upwards and forwards visual axis and provides spectral tuning in downwelling light environment. That results from the differentiation of cone types by size and by different spectral sensitivity of various retinal areas. J. Morphol. 277:472–481, 2016. © 2016 Wiley Periodicals, Inc. 相似文献
114.
On seedlings of winter wheat (Triticum aestivum L.) and cucumber (Cucumis sativus L.), the dynamics of cysteine and serine trypsin-like proteinases and also trypsin inhibitors at cold hardening (5°C for
wheat and 10°C for cucumber) was studied. Activation of proteinases and inhibitors coincided in time or preceded an increased
tolerance in wheat and cucumber seedlings in the early period of their hardening. After attaining the highest wheat tolerance,
activity amidases reduced, whereas the increased activity levels of cysteine proteinases and trypsin inhibitors was maintained
during the entire period of hardening. In cucumber, in these period activities of amidases and trypsin inhibitors reduced,
whereas the activity of cysteine proteinases was maintained at the level close to the initial one. It is suggested that cysteine
proteinases, amidases, and trypsin inhibitors are involved in plant adaptation to cold. 相似文献
115.
A. D. Solovieva O. Yu. Frolova A. G. Solovyev S. Yu. Morozov A. A. Zamyatnin Jr. 《Biochemistry. Biokhimii?a》2013,78(9):1006-1012
Programmed cell death (PCD) is the main defense mechanism in plants to fight various pathogens including viruses. The best-studied example of virus-induced PCD in plants is Tobacco mosaic virus (TMV)-elicited hypersensitive response in tobacco plants containing the N resistance gene. It was previously reported that the animal mitochondrial protein Bcl-xL, which lacks a homolog in plants, effectively suppresses plant PCD induced by TMV p50 — the elicitor of hyper-sensitive response in Nicotiana tabacum carrying the N gene. Our studies show that the mitochondria-targeted antioxidant SkQ1 effectively suppresses p50-induced PCD in tobacco plants. On the other hand, SkQ1 did not affect Poa semilatent virus TGB3-induced endoplasmic reticulum stress, which is followed by PCD, in Nicotiana benthamiana epidermal cells. These data suggest that mitochondria-targeted antioxidant SkQ1 can be used to study molecular mechanisms of PCD suppression in plants. 相似文献
116.
Niall J. Foy Maryna Akhrymuk Alexander V. Shustov Elena I. Frolova Ilya Frolov 《Journal of virology》2013,87(13):7569-7584
Venezuelan equine encephalitis virus (VEEV) is one of the most pathogenic members of the Alphavirus genus in the Togaviridae family. This genus is divided into the Old World and New World alphaviruses, which demonstrate profound differences in pathogenesis, replication, and virus-host interactions. VEEV is a representative member of the New World alphaviruses. The biology of this virus is still insufficiently understood, particularly the function of its nonstructural proteins in RNA replication and modification of the intracellular environment. One of these nonstructural proteins, nsP3, contains a hypervariable domain (HVD), which demonstrates very low overall similarity between different alphaviruses, suggesting the possibility of its function in virus adaptation to different hosts and vectors. The results of our study demonstrate the following. (i) Phosphorylation of the VEEV nsP3-specific HVD does not play a critical role in virus replication in cells of vertebrate origin but is important for virus replication in mosquito cells. (ii) The VEEV HVD is not required for viral RNA replication in the highly permissive BHK-21 cell line. In fact, it can be either completely deleted or replaced by a heterologous protein sequence. These variants require only one or two additional adaptive mutations in nsP3 and/or nsP2 proteins to achieve an efficiently replicating phenotype. (iii) However, the carboxy-terminal repeat in the VEEV HVD is indispensable for VEEV replication in the cell lines other than BHK-21 and plays a critical role in formation of VEEV-specific cytoplasmic protein complexes. Natural VEEV variants retain at least one of the repeated elements in their nsP3 HVDs. 相似文献
117.
Jungheim ES Louden ED Chi MM Frolova AI Riley JK Moley KH 《Biology of reproduction》2011,85(4):678-683
Free fatty acids (FFAs) are energy substrates for many cell types, but in excess, some FFAs can accumulate in nonadipose cells, inducing apoptosis. Also known as lipotoxicity, this phenomenon may play a role in the development of obesity-related disease. Obesity is common among reproductive age women and is associated with adverse pregnancy and fetal outcomes; however, little is known about the effects of excess FFAs on embryos and subsequent fetal development. To address this knowledge gap, murine blastocysts were cultured in excess palmitic acid (PA), the most abundant saturated FFA in human serum, and ovarian follicular fluid. Targets susceptible to aberrations in maternal physiology, including embryonic IGF1 receptor (IGF1R) expression, glutamic pyruvate transaminase (GPT2) activity, and nuclei count, were measured. PA-exposed blastocysts demonstrated altered IGF1R expression, increased GPT2 activity, and decreased nuclei count. Trophoblast stem cells derived from preimplantation embryos were also cultured in PA. Cells exposed to increasing doses of PA demonstrated increased apoptosis and decreased proliferation. To demonstrate long-term effects of brief PA exposure, blastocysts cultured for 30 h in PA were transferred into foster mice, and pregnancies followed through Embryonic Day (ED)14.5 or delivery. Fetuses resulting from PA-exposed blastocysts were smaller than controls at ED14.5. Delivered pups were also smaller but demonstrated catch-up growth and ultimately surpassed control pups in weight. Altogether, our data suggest brief PA exposure results in altered embryonic metabolism and growth, with lasting adverse effects on offspring, providing further insight into the pathophysiology of maternal obesity. 相似文献
118.
Alexander V. Shpatov Tatyana S. Frolova Sergey A. Popov Olga I. Sinitsyna Olga I. Salnikova Guangyao Zheng Linlin Yan Nadezhda V. Sinelnikova Lyudmila M. Pshennikova Alexey V. Kochetov 《化学与生物多样性》2020,17(8)
Lipophilic extractive metabolites from needles and defoliated twigs of Pinus armandii and P. kwangtungensis were studied by GC/MS. Needles of P. armandii contained predominantly 15‐O‐functionalized labdane type acids (anticopalic acid), fatty acids, nonacosan‐10‐ol, sterols, nonacosan‐10‐ol and sterol saponifiable esters, and acylglycerols, while P. kwangtungensis needles contained no anticopalic acid, but more trinorlabdane (14,15,16‐trinor‐8(17)‐labdene‐13,19‐dioic acid) and other labdane type acids, nonacosan‐10‐ol and its saponifiable esters. The major compounds in the P. armandii defoliated twig extract were abietane and isopimarane type acids, fatty acids, sterols, labdanoids (cis‐abienol), cembranoids (isocembrol and 4‐epi‐isocembrol), saponifiable sterol esters, and acylglycerols. The same extract of P. kwangtungensis contained larger quantities of fatty acids, caryophyllene oxide, serratanoids, sterols, saponifiable sterol esters, and acylglycerols, but lesser amounts of abietane and isopimarane type acids, cis‐abienol, and lacked cembranoids. Both twig and needle extracts of P. armandii and P. kwangtungensis, as well as the extracts’ fractions, significantly inhibited the growth of Gram‐negative bacteria Serratia marcescens with MIC of 0.1 mg ml?1, while in most cases they slightly stimulated the growth of Gram‐positive bacteria Bacillus subtilis at the same concentrations. Thus, lipophilic extractive compounds from the needles and defoliated twigs of both pines are prospective for the development of antiseptics against Gram‐negative bacteria. 相似文献
119.
David?A?Qualls Mercedes?Prudencio Brittany?LT?Roberts Keith?Crosby Hilda?Brown David?R?BorcheltEmail author 《Molecular neurodegeneration》2013,8(1):46
Mutations in the gene encoding superoxide dismutase 1 (SOD1) account for about 20% of the cases of familial amyotrophic lateral sclerosis (fALS). It is well established that mutations in SOD1, associated with fALS, heighten the propensity of the protein to misfold and aggregate. Although aggregation appears to be a factor in the toxicity of mutant SOD1s, the precise nature of this toxicity has not been elucidated. A number of other studies have now firmly established that raising the levels of wild-type (WT) human SOD1 (hSOD1) proteins can in some manner augment the toxicity of mutant hSOD1 proteins. However, a recent study demonstrated that raising the levels of WT-hSOD1 did not affect disease in mice that harbor a mouse Sod1 gene (mSod1) encoding a well characterized fALS mutation (G86R). In the present study, we sought a potential explanation for the differing effects with WT-hSOD1 on the toxicity of mutant hSOD1 versus mutant mSod1. In the cell culture models used here, we observe poor interactions between WT-hSOD1 and misfolded G86R-mSod1, possibly explaining why over-expression of WT-hSOD1 does not synergize with mutant mSod1 to accelerate the course of the disease in mice. 相似文献
120.
Onishchenko GG Ezhlova EB Mel'nikova AA Lazikova GF Demina IuV Frolova NV 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》2011,(2):12-22
Problem of emergence and spread of poliomyelitis in Russian Federation and neighboring states is examined. Measures taken in Russian Federation to prevent emergence of poliomyelitis cases caused by wild type virus are discussed, as well as treaties and agreements between Russia, Commonwealth of Independent States, Shanghai Cooperation Organization states regarding epidemiological control of poliomyelitis and acute flaccid paralysis. Measure planned by Federal Service for Surveillance for Protection of Consumers Rights and Human Welfare to prevent emergence of poliomyelitis and acute flaccid paralysis cases in Russian Federation and neighboring countries are presented. 相似文献