全文获取类型
收费全文 | 1378篇 |
免费 | 106篇 |
国内免费 | 16篇 |
出版年
2023年 | 11篇 |
2022年 | 10篇 |
2021年 | 33篇 |
2020年 | 21篇 |
2019年 | 25篇 |
2018年 | 36篇 |
2017年 | 31篇 |
2016年 | 46篇 |
2015年 | 63篇 |
2014年 | 58篇 |
2013年 | 81篇 |
2012年 | 108篇 |
2011年 | 81篇 |
2010年 | 59篇 |
2009年 | 50篇 |
2008年 | 57篇 |
2007年 | 59篇 |
2006年 | 51篇 |
2005年 | 58篇 |
2004年 | 51篇 |
2003年 | 65篇 |
2002年 | 37篇 |
2001年 | 38篇 |
2000年 | 40篇 |
1999年 | 27篇 |
1998年 | 15篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 13篇 |
1992年 | 23篇 |
1991年 | 21篇 |
1990年 | 18篇 |
1989年 | 13篇 |
1988年 | 16篇 |
1987年 | 20篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1979年 | 9篇 |
1978年 | 10篇 |
1976年 | 6篇 |
1974年 | 5篇 |
1972年 | 12篇 |
1970年 | 5篇 |
1968年 | 6篇 |
1967年 | 9篇 |
1965年 | 7篇 |
排序方式: 共有1500条查询结果,搜索用时 15 毫秒
81.
Taxol is an anticancer drug that triggers apoptosis in a wide spectrum of cancers such as ovarian, breast, lung, head and neck, and bladder carcinoma by both caspase-dependent and -independent apoptosis mechanisms. However, the exact signaling pathways involved in taxol-induced apoptosis strongly depend on the cellular background and they are not completely established yet. In this study we demonstrate that taxol induces caspase-3-independent apoptosis in NIH3T3 cells by a calpain-mediated mechanism. Taxol treatment produced changes in the mitochondrial membrane potential (Delta Psi m) which could be responsible of Ca(2+) release from the mitochondria and the consequent calpain activation. Interestingly, we show that calpain produced proteolysis of caspase-3 and demonstrate that, accordingly, calpain inhibition increased taxol-induced apoptosis. In addition, we reveal that poly (ADP-ribose) polymerase (PARP) was processed by calpain in taxol-treated cells and by caspase-3 after calpain inhibition. In conclusion, these results demonstrate for the first time that calpain could play an important role modulating taxol-induced apoptosis. Further studies are needed to address the potentiality of inducing apoptosis by a combined use of taxol and calpain inhibitors in cells with increased calpain activity. 相似文献
82.
Piñeiro D González VM Hernández-Jiménez M Salinas M Martín ME 《Experimental cell research》2007,313(17):3694-3706
Changes to the translational machinery that occur during apoptosis have been described in the last few years. The two principal ways in which translational factors are modified during apoptosis are: (i) changes in protein phosphorylation and (ii) specific proteolytic cleavages. Taxol, a member of a new class of anti-tubulin drugs, is currently used in chemotherapeutic treatments of different types of cancers. We have previously demonstrated that taxol induces calpain-mediated apoptosis in NIH3T3 cells [Pi?eiro et al., Exp. Cell Res., 2007, 313:369-379]. In this study we found that translation was significantly inhibited during taxol-induced apoptosis in these cells. We have studied the phosphorylation status and expression levels of eIF2a, eIF4E, eIF4G and the regulatory protein 4E-BP1, all of which are implicated in translation regulation. We found that taxol treatment did not induce changes in eIF2alpha phosphorylation, but strongly decreased eIF4G, eIF4E and 4E-BP1 expression levels. MDL28170, a specific inhibitor of calpain, prevented reduction of eIF4G, but not of eIF4E or 4E-BP1 levels. Moreover, the calpain inhibitor did not block taxol-induced translation inhibition. All together these findings demonstrated that none of these factors are responsible for the taxol-induced protein synthesis inhibition. On the contrary, taxol treatment increased elongation factor eEF2 phosphorylation in a calpain-independent manner, supporting a role for eEF2 in taxol-induced translation inhibition. 相似文献
83.
Macholán M Munclinger P Sugerková M Dufková P Bímová B Bozíková E Zima J Piálek J 《Evolution; international journal of organic evolution》2007,61(4):746-771
In this paper, we present results of the first comprehensive study of the introgression of both autosomal and sex-chromosome markers across the central European portion of the hybrid zone between two house mouse subspecies, Mus musculus musculus and M. m. domesticus. More than 1800 individuals sampled from 105 sites were analyzed with a set of allozyme loci (hopefully representing neutral or nearly neutral markers) and X-linked loci (which are assumed to be under selection). The zone center is best modeled as a single straight line independent of fine-scale local geographic or climatic conditions, being maintained by a balance between dispersal and selection against hybrids. The width (w) of the multilocus autosomal cline was estimated as 9.6 km whereas the estimate for the compound X-chromosome cline was about 4.6 km only. As the former estimate is comparable to that of the Danish portion of the zone (assumed to be much younger than the central European one), zone width does not appear to be related to its age. The strength (B) of the central barrier was estimated as about 20 km; with dispersal (sigma) of about 1 km/gen(1/2), this means effective selection (s*) is approximately 0.06-0.09 for autosomal loci and about 0.25 for X-linked loci. The number of loci under selection was estimated as N= 56-99 for autosomes and about 380 for X-linked loci. Finally, we highlight some potential pitfalls in hybrid zone analyses and in comparisons of different transects. We suggest that conclusions about parts of the mouse genome involved in reproductive isolation and speciation should be drawn with caution and that analytical approaches always providing some estimates should not be used without due care regarding the support or confidence of such estimates, especially if conclusions are based on the difference between these estimates. Finally, we recommend that analysis in two-dimensional space, dense sampling, and rigorous treatment of data, including inspection of likelihood profiles, are essential for hybrid zone studies. 相似文献
84.
Pig acute-phase protein levels after stress induced by changes in the pattern of food administration
Piñeiro C Piñeiro M Morales J Carpintero R Campbell FM Eckersall PD Toussaint MJ Alava MA Lampreave F 《Animal : an international journal of animal bioscience》2007,1(1):133-139
A total of 240 pigs, 74 days old, half boars and half females, were included in a trial designed to assess the effect of the stress caused by changes in the pattern of food administration on the concentration of acute phase proteins (APP) and productive performance parameters. Half of the animals (pigs fed ad libitum, AL group) had free access to feed, while the rest were fed following a disorderly pattern (DIS group), in which animals had alternating periods of free access to feed and periods of no feeding, when food was removed from the feeder. The periods of free access to feed (two daily periods of 2-h duration) were randomly assigned, and varied from day to day. Total feed supplied per day was identical in both groups, and exceeded the minimal amount required for animals of these ages. Pen feed intake, individual body weights and the main positive pig APP pig major acute phase protein (Pig-MAP), haptoglobin, serum amyloid A (SAA), C-reactive protein (CRP), and the negative APP apolipoprotein A-I (ApoA-I) and transtherytin were determined every 2 weeks during the period 76 to 116 days of age. Animals fed ad libitum had better average daily gain (ADG) than DIS animals in the whole experimental period (P < 0.01) but the differences in ADG were only produced in the two first experimental sub-periods (60 to 74 and 74 to 116 days of age), suggesting that the stress diminished when the animals get used to the DIS feeding. Interestingly differences in ADG between DIS and AL pigs were due to males, whereas no differences were observed between females. The same differences observed for ADG were found for APP. DIS males had higher Pig-MAP concentration than AL males at 74 and 116 days of age, lower ApoA-I concentration at 74 days of age and higher haptoglobin and CRP concentration at 116 days of age (P < 0.05). The results obtained in this trial show an inverse relationship between weight gain and APP levels, and suggest that APP may be biomarkers for the evaluation of distress and welfare in pigs. 相似文献
85.
A new smut fungus Ustilago aldabrensis on the grass Dactyloctenium ctenoides is described and illustrated from Aldabra Island in the Seychelles archipelago. It is compared with similar species known
on the genus Dactyloctenium. A further two smut fungi infecting this host plant genus, U. dactyloctenii-gigantei and U. idonea are discussed. U. dactyloctenii-gigantei is reported for the first time from Nigeria on a new host plant, D. aegyptium. U. idonea is redescribed, and its nomenclature and geographical distribution are clarified. A key to smut fungi infecting species of
Dactyloctenium is provided. 相似文献
86.
Říčan Oldřich Říčanová Štěpánka Dragová Klára Piálek Lubomír Almirón Adriana Casciotta Jorge 《Hydrobiologia》2019,832(1):331-354
Hydrobiologia - We address the diversity of two species groups of the cichlid genus Gymnogeophagus in the Middle Paraná basin using molecular phylogeography and traditional morphological... 相似文献
87.
88.
89.
Plant Ecology - In forests, the majority of fine roots are located within the upper soil horizons, and fine root biomass decreases with depth. We evaluated spatial patterns in the distribution of... 相似文献
90.