全文获取类型
收费全文 | 1271篇 |
免费 | 213篇 |
出版年
2019年 | 13篇 |
2017年 | 18篇 |
2016年 | 22篇 |
2015年 | 27篇 |
2014年 | 45篇 |
2013年 | 47篇 |
2012年 | 62篇 |
2011年 | 54篇 |
2010年 | 40篇 |
2009年 | 30篇 |
2008年 | 38篇 |
2007年 | 48篇 |
2006年 | 48篇 |
2005年 | 37篇 |
2004年 | 45篇 |
2003年 | 45篇 |
2002年 | 44篇 |
2001年 | 39篇 |
2000年 | 48篇 |
1999年 | 35篇 |
1998年 | 24篇 |
1997年 | 25篇 |
1996年 | 14篇 |
1995年 | 20篇 |
1994年 | 17篇 |
1993年 | 19篇 |
1992年 | 28篇 |
1991年 | 33篇 |
1990年 | 38篇 |
1989年 | 13篇 |
1988年 | 15篇 |
1987年 | 18篇 |
1986年 | 21篇 |
1985年 | 13篇 |
1984年 | 23篇 |
1983年 | 14篇 |
1982年 | 15篇 |
1981年 | 13篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 19篇 |
1976年 | 12篇 |
1975年 | 18篇 |
1974年 | 25篇 |
1973年 | 25篇 |
1972年 | 23篇 |
1971年 | 18篇 |
1970年 | 19篇 |
1969年 | 12篇 |
1968年 | 16篇 |
排序方式: 共有1484条查询结果,搜索用时 931 毫秒
861.
862.
Robert N. Booher Harold Hatch Brian M. Dolinski Thi Nguyen Lauren Harmonay Ali-Samer Al-Assaad Mark Ayers Michael Nebozhyn Andrey Loboda Heather A. Hirsch Theresa Zhang Bin Shi Carrie E. Merkel Minilik H. Angagaw Yaolin Wang Brian J. Long Xianlu Q. Lennon Nathan Miselis Vincenzo Pucci James W. Monahan Junghoon Lee Anna Georgieva Kondic Eun Kyung Im David Mauro Rebecca Blanchard Gary Gilliland Stephen E. Fawell Leigh Zawel Alwin G. Schuller Peter Strack 《PloS one》2014,9(10)
Dinaciclib is a potent CDK1, 2, 5 and 9 inhibitor being developed for the treatment of cancer. Additional understanding of antitumor mechanisms and identification of predictive biomarkers are important for its clinical development. Here we demonstrate that while dinaciclib can effectively block cell cycle progression, in vitro and in vivo studies, coupled with mouse and human pharmacokinetics, support a model whereby induction of apoptosis is a main mechanism of dinaciclib''s antitumor effect and relevant to the clinical duration of exposure. This was further underscored by kinetics of dinaciclib-induced downregulation of the antiapoptotic BCL2 family member MCL1 and correlation of sensitivity with the MCL1-to-BCL-xL mRNA ratio or MCL1 amplification in solid tumor models in vitro and in vivo. This MCL1-dependent apoptotic mechanism was additionally supported by synergy with the BCL2, BCL-xL and BCL-w inhibitor navitoclax (ABT-263). These results provide the rationale for investigating MCL1 and BCL-xL as predictive biomarkers for dinaciclib antitumor response and testing combinations with BCL2 family member inhibitors. 相似文献
863.
H. Lemriss Martins Sim?es P S. Lemriss M. Butin A. Ibrahimi S. El Kabbaj JP Rasigade F. Laurent 《Standards in genomic sciences》2014,9(3):1118-1127
Staphylococcus capitis is a coagulase-negative staphylococcus (CoNS) commonly found in the human microflora. Recently, a clonal population of Staphylococcus capitis (denominated NRCS-A) was found to be a major cause of late-onset sepsis (LOS) in several neonatal intensive care units in France. Here, we report the complete genome sequence and annotation of the prototype Staphylococcus capitis NCRS-A strain CR01. The 2,504,472 bp long genome (1 chromosome and no plasmids) exhibits a G+C content of 32.81%, and contains 2,468 protein-coding and 59 tRNA genes and 4 rRNA genes. 相似文献
864.
865.
The intrinsic fluorescence of hemoglobins is known to respond to ligand-induced changes in the quaternary structure of the protein. Carp hemoglobin is an interesting model to study the quaternary transition since its R----T equilibrium is pH-dependent and at low pH, in the presence of organic phosphate, it remains in the T or 'deoxy' quaternary structure, even when saturated with ligand. In this study, using front-face fluorometry, we show that the intrinsic fluorescence intensity exhibited by carp carboxyhemoglobin increases as the pH is lowered below 6.5 in the presence of inositol hexaphosphate. At low pH, carp methemoglobin is less affected by the addition of inositol hexaphosphate than is the CO derivative, while little or no change is observed in the met-azide derivative. We conclude: (1) the exact nature of the R to T state transition induced by inositol hexaphosphate differs for carp carboxy-, met- and met-azide hemoglobin derivatives; (2) the chromophores responsible for the changes observed with absorption spectroscopy may not be the same as those chromophores responsible for the fluorescence differences; and (3) alpha 46-Trp is tentatively assigned as one source of fluorescence emission. Furthermore, fluorescence properties of carp hemoglobin are compared to those of human hemoglobin. 相似文献
866.
Laura L. Phelan Zachary A. Rodd Helmut V. B. Hirsch Robert A. Rosellini 《Physiological Entomology》2001,26(3):219-224
Abstract. Temperature changes can be especially threatening for ectotherms, such as Drosophila melanogaster (Diptera: Drosophilidea Meigen, 1830 ), and in this study we tested whether flies can associate olfactory stimuli with a sudden drop in temperature. Such Pavlovian conditioning would allow them to make appropriate behavioural and/or physiological responses in the future. We found that exposing individual flies to one of two odours in the presence of a sudden drop in temperature resulted in Pavlovian conditioning with flies subsequently avoiding the odour paired with cold. The characteristics of Pavlovian conditioning in flies were comparable to those observed for mammalian species. Specifically, the strength of conditioning increased with increasing intensity of the cold and decreased as the time interval between the olfactory stimulus (CS) and cold (US) was lengthened. Finally, the order in which CS and US were presented affected the strength of conditioning. Learning was observed when the CS preceded US and when the US immediately preceded the CS, but not when the CS preceded the US by 30 s or more. These results provide further evidence for learning in individual flies, and confirm that Pavlovian conditioning is a general mechanism used by organisms to obtain information about their environment. 相似文献
867.
Christoph Wallner Jessica Schira Johannes Maximilian Wagner Matthias Schulte Sebastian Fischer Tobias Hirsch Wiltrud Richter Stephanie Abraham Ulrich Kneser Marcus Lehnhardt Bj?rn Behr 《PloS one》2015,10(3)
Although bone regeneration is typically a reliable process, type 2 diabetes is associated with impaired or delayed healing processes. In addition, angiogenesis, a crucial step in bone regeneration, is often altered in the diabetic state. In this study, different stages of bone regeneration were characterized in an unicortical bone defect model comparing transgenic type 2 diabetic (db-/db-) and wild type (WT) mice in vivo. We investigated angiogenesis, callus formation and bone remodeling at early, intermediate and late time points by means of histomorphometry as well as protein level analyses. In order to enhance bone regeneration, defects were locally treated with recombinant FGF-9 or VEGFA. Histomorphometry of aniline blue stained sections indicated that bone regeneration is significantly decreased in db-/db- as opposed to WT mice at intermediate (5 days post operation) and late stages (7 days post operation) of bone regeneration. Moreover, immunohistochemical analysis revealed significantly decreased levels of RUNX-2, PCNA, Osteocalcin and PECAM-1 in db-/db- defects. In addition, osteoclastogenesis is impaired in db-/db- indicating altered bone remodeling. These results indicate significant impairments in angiogenesis and osteogenesis in type 2 diabetic bones. Importantly, angiogenesis, osteogenesis and bone remodeling could be reconstituted by application of recombinant FGF-9 and, in part, by VEGFA application. In conclusion, our study demonstrates that type 2 diabetes affects angiogenesis, osteogenesis and subsequently bone remodeling, which in turn leads to decreased bone regeneration. These effects could be reversed by local application of FGF-9 and to a lesser degree VEGFA. These data could serve as a basis for future therapeutic applications aiming at improving bone regeneration in the type 2 diabetic patient population. 相似文献
868.
High genetic diversity declines towards the geographic range periphery of Adonis vernalis,a Eurasian dry grassland plant
下载免费PDF全文
![点击此处可从《Plant biology (Stuttgart, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
H. Hirsch V. Wagner J. Danihelka E. Ruprecht P. Sánchez‐Gómez M. Seifert I. Hensen 《Plant biology (Stuttgart, Germany)》2015,17(6):1233-1241
Genetic diversity is important for species' fitness and evolutionary processes but our knowledge on how it varies across a species' distribution range is limited. The abundant centre hypothesis (ACH) predicts that populations become smaller and more isolated towards the geographic range periphery – a pattern that in turn should be associated with decreasing genetic diversity and increasing genetic differentiation. We tested this hypothesis in Adonis vernalis, a dry grassland plant with an extensive Eurasian distribution. Its life‐history traits and distribution characteristics suggest a low genetic diversity that decreases and a high genetic differentiation that increases towards the range edge. We analysed AFLP fingerprints in 28 populations along a 4698‐km transect from the geographic range core in Russia to the western range periphery in Central and Western Europe. Contrary to our expectation, our analysis revealed high genetic diversity (range of proportion of polymorphic bands = 56–81%, He = 0.168–0.238) and low genetic differentiation across populations (ΦST = 0.18). However, in congruence with the genetic predictions of the ACH, genetic diversity decreased and genetic differentiation increased towards the range periphery. Spanish populations were genetically distinct, suggesting a divergent post‐glacial history in this region. The high genetic diversity and low genetic differentiation in the remaining A. vernalis populations is surprising given the species' life‐history traits and points to the possibility that the species has been widely distributed in the studied region or that it has migrated from a diverse source in an East–West direction, in the past. 相似文献
869.
Rodrigo Lima Massara Ana Maria de Oliveira Paschoal Paul Francis Doherty Jr. André Hirsch Adriano Garcia Chiarello 《PloS one》2015,10(11)
Forest fragmentation and habitat loss are detrimental to top carnivores, such as jaguars (Panthera onca) and pumas (Puma concolor), but effects on mesocarnivores, such as ocelots (Leopardus pardalis), are less clear. Ocelots need native forests, but also might benefit from the local extirpation of larger cats such as pumas and jaguars through mesopredator release. We used a standardized camera trap protocol to assess ocelot populations in six protected areas of the Atlantic forest in southeastern Brazil where over 80% of forest remnants are < 50 ha. We tested whether variation in ocelot abundance could be explained by reserve size, forest cover, number of free-ranging domestic dogs and presence of top predators. Ocelot abundance was positively correlated with reserve size and the presence of top predators (jaguar and pumas) and negatively correlated with the number of dogs. We also found higher detection probabilities in less forested areas as compared to larger, intact forests. We suspect that smaller home ranges and higher movement rates in smaller, more degraded areas increased detection. Our data do not support the hypothesis of mesopredator release. Rather, our findings indicate that ocelots respond negatively to habitat loss, and thrive in large protected areas inhabited by top predators. 相似文献
870.
Lauren R. Biehle Jessica M. Cottreau David J. Thompson Rachel L. Filipek J. Nicholas O’Donnell Todd M. Lasco Monica V. Mahoney Elizabeth B. Hirsch 《PloS one》2015,10(11)