全文获取类型
收费全文 | 1372篇 |
免费 | 86篇 |
国内免费 | 2篇 |
出版年
2023年 | 6篇 |
2022年 | 30篇 |
2021年 | 47篇 |
2020年 | 23篇 |
2019年 | 28篇 |
2018年 | 48篇 |
2017年 | 33篇 |
2016年 | 43篇 |
2015年 | 60篇 |
2014年 | 67篇 |
2013年 | 102篇 |
2012年 | 95篇 |
2011年 | 93篇 |
2010年 | 52篇 |
2009年 | 55篇 |
2008年 | 71篇 |
2007年 | 67篇 |
2006年 | 72篇 |
2005年 | 55篇 |
2004年 | 54篇 |
2003年 | 53篇 |
2002年 | 38篇 |
2001年 | 22篇 |
2000年 | 23篇 |
1999年 | 18篇 |
1998年 | 11篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 10篇 |
1991年 | 12篇 |
1989年 | 11篇 |
1988年 | 11篇 |
1987年 | 11篇 |
1986年 | 8篇 |
1983年 | 13篇 |
1982年 | 5篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1977年 | 8篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1972年 | 7篇 |
1969年 | 4篇 |
1967年 | 9篇 |
1965年 | 3篇 |
1964年 | 3篇 |
排序方式: 共有1460条查询结果,搜索用时 15 毫秒
81.
Roland Frey Alban Gebler Kirk A. Olson Daria Odonkhuu Guido Fritsch Nyamsuren Batsaikhan Ingo W. Stuermer 《Journal of morphology》2008,269(10):1223-1237
This study provides the first evidence of pronounced temporary laryngeal descent in a bovid species. An elaborate acoustic display is prominent in male courtship behavior of polygynous Mongolian gazelle. During rut, rounding up of females is accompanied by continuous head‐up barking by dominant males. Throughout the rut their evolutionarily enlarged larynx descends to a low mid‐neck resting position. In the course of each bark the larynx is additionally retracted toward the sternum by 30% of the resting vocal tract length. A geometric model of active larynx movements was constructed by combining results of video documentation, dissection, skeletonization, and behavioral observation. The considerable distance between resting position and maximal laryngeal descent suggests a backward tilting of the hyoid apparatus and an extension of the thyrohyoid connection during the retraction phase. Return to the resting position is effected by strap muscles and by the elastic recoil of the pharynx and the thyrohyoid connection. An intrapharyngeal inflation of the peculiar palatinal pharyngeal pouch of adult males is inferred from a short‐time expansion of the ventral neck region rostral to the laryngeal prominence. The neck of adult dominant males is accentuated by long gray guard hairs during the rut. The passive swinging of the heavy larynx of adult males during locomotion gives the impression of a handicap imposed on rutting males. Apparently, this disadvantage becomes outweighed by the profits for reproductive success. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc. 相似文献
82.
83.
Katarzyna Danis-Wlodarczyk Tomasz Olszak Michal Arabski Slawomir Wasik Grazyna Majkowska-Skrobek Daria Augustyniak Grzegorz Gula Yves Briers Ho Bin Jang Dieter Vandenheuvel Katarzyna Anna Duda Rob Lavigne Zuzanna Drulis-Kawa 《PloS one》2015,10(5)
We here describe two novel lytic phages, KT28 and KTN6, infecting Pseudomonas aeruginosa, isolated from a sewage sample from an irrigated field near Wroclaw, in Poland. Both viruses show characteristic features of Pbunalikevirus genus within the Myoviridae family with respect to shape and size of head/tail, as well as LPS host receptor recognition. Genome analysis confirmed the similarity to other PB1-related phages, ranging between 48 and 96%. Pseudomonas phage KT28 has a genome size of 66,381 bp and KTN6 of 65,994 bp. The latent period, burst size, stability and host range was determined for both viruses under standard laboratory conditions. Biofilm eradication efficacy was tested on peg-lid plate assay and PET membrane surface. Significant reduction of colony forming units was observed (70-90%) in 24 h to 72 h old Pseudomonas aeruginosa PAO1 biofilm cultures for both phages. Furthermore, a pyocyanin and pyoverdin reduction tests reveal that tested phages lowers the amount of both secreted dyes in 48-72 h old biofilms. Diffusion and goniometry experiments revealed the increase of diffusion rate through the biofilm matrix after phage application. These characteristics indicate these phages could be used to prevent Pseudomonas aeruginosa infections and biofilm formation. It was also shown, that PB1-related phage treatment of biofilm caused the emergence of stable phage-resistant mutants growing as small colony variants. 相似文献
84.
Long Tree-Ring Chronologies Provide Evidence of Recent Tree Growth Decrease in a Central African Tropical Forest 总被引:1,自引:0,他引:1
Giovanna Battipaglia Enrica Zalloni Simona Castaldi Fabio Marzaioli Roberto Cazzolla- Gatti Bruno Lasserre Roberto Tognetti Marco Marchetti Riccardo Valentini 《PloS one》2015,10(3)
It is still unclear whether the exponential rise of atmospheric CO2 concentration has produced a fertilization effect on tropical forests, thus incrementing their growth rate, in the last two centuries. As many factors affect tree growth patterns, short -term studies might be influenced by the confounding effect of several interacting environmental variables on plant growth. Long-term analyses of tree growth can elucidate long-term trends of plant growth response to dominant drivers. The study of annual rings, applied to long tree-ring chronologies in tropical forest trees enables such analysis. Long-term tree-ring chronologies of three widespread African species were measured in Central Africa to analyze the growth of trees over the last two centuries. Growth trends were correlated to changes in global atmospheric CO2 concentration and local variations in the main climatic drivers, temperature and rainfall. Our results provided no evidence for a fertilization effect of CO2 on tree growth. On the contrary, an overall growth decline was observed for all three species in the last century, which appears to be significantly correlated to the increase in local temperature. These findings provide additional support to the global observations of a slowing down of C sequestration in the trunks of forest trees in recent decades. Data indicate that the CO2 increase alone has not been sufficient to obtain a tree growth increase in tropical trees. The effect of other changing environmental factors, like temperature, may have overridden the fertilization effect of CO2. 相似文献
85.
86.
87.
Daria A. Gaykalova Rajita Vatapalli Yingying Wei Hua-Ling Tsai Hao Wang Chi Zhang Patrick T. Hennessey Theresa Guo Marietta Tan Ryan Li Julie Ahn Zubair Khan William H. Westra Justin A. Bishop David Zaboli Wayne M. Koch Tanbir Khan Michael F. Ochs Joseph A. Califano 《PloS one》2015,10(11)
Head and Neck Squamous Cell Carcinoma (HNSCC) is the fifth most common cancer, annually affecting over half a million people worldwide. Presently, there are no accepted biomarkers for clinical detection and surveillance of HNSCC. In this work, a comprehensive genome-wide analysis of epigenetic alterations in primary HNSCC tumors was employed in conjunction with cancer-specific outlier statistics to define novel biomarker genes which are differentially methylated in HNSCC. The 37 identified biomarker candidates were top-scoring outlier genes with prominent differential methylation in tumors, but with no signal in normal tissues. These putative candidates were validated in independent HNSCC cohorts from our institution and TCGA (The Cancer Genome Atlas). Using the top candidates, ZNF14, ZNF160, and ZNF420, an assay was developed for detection of HNSCC cancer in primary tissue and saliva samples with 100% specificity when compared to normal control samples. Given the high detection specificity, the analysis of ZNF DNA methylation in combination with other DNA methylation biomarkers may be useful in the clinical setting for HNSCC detection and surveillance, particularly in high-risk patients. Several additional candidates identified through this work can be further investigated toward future development of a multi-gene panel of biomarkers for the surveillance and detection of HNSCC. 相似文献
88.
89.
Magdalena Paczkowska Miko?aj Mizera Hanna Piotrowska Daria Szymanowska-Powa?owska Kornelia Lewandowska Joanna Goscianska Robert Pietrzak Waldemar Bednarski Zbigniew Majka Judyta Cielecka-Piontek 《PloS one》2015,10(3)
This study aimed to obtain and characterize an RU-β-CD complex in the context of investigating the possibility of changes in the solubility, stability, antioxidative and microbiological activity as well as permeability of complexated rutin as against its free form. The formation of the RU-β-CD complex via a co-grinding technique was confirmed by using DSC, SEM, FT-IR and Raman spectroscopy, and its geometry was assessed through molecular modeling. It was found that the stability and solubility of the so-obtained complex were greater compared to the free form; however, a slight decrease was observed inits antibacterial potency. An examination of changes in the EPR spectra of thecomplex excluded any reducing effect of complexation on the antioxidative activity of rutin. Considering the prospect of preformulation studies involving RU-β-CD complexes, of significance is also the observed possibility of prolongedly releasing rutin from the complex at a constant level over along period of 20 h, and the fact that twice as much complexated rutin was able topermeate compared to its free form. 相似文献
90.