全文获取类型
收费全文 | 842篇 |
免费 | 99篇 |
出版年
2020年 | 9篇 |
2018年 | 13篇 |
2017年 | 12篇 |
2016年 | 11篇 |
2015年 | 17篇 |
2014年 | 14篇 |
2013年 | 20篇 |
2012年 | 41篇 |
2011年 | 38篇 |
2010年 | 20篇 |
2009年 | 18篇 |
2008年 | 27篇 |
2007年 | 27篇 |
2006年 | 32篇 |
2005年 | 31篇 |
2004年 | 32篇 |
2003年 | 43篇 |
2002年 | 24篇 |
2001年 | 20篇 |
2000年 | 25篇 |
1999年 | 14篇 |
1998年 | 16篇 |
1994年 | 14篇 |
1993年 | 13篇 |
1992年 | 17篇 |
1991年 | 16篇 |
1990年 | 17篇 |
1989年 | 16篇 |
1988年 | 16篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 18篇 |
1984年 | 15篇 |
1983年 | 7篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 12篇 |
1979年 | 8篇 |
1978年 | 20篇 |
1977年 | 11篇 |
1976年 | 16篇 |
1975年 | 9篇 |
1974年 | 9篇 |
1973年 | 8篇 |
1972年 | 9篇 |
1971年 | 14篇 |
1970年 | 11篇 |
1968年 | 8篇 |
1967年 | 13篇 |
1966年 | 7篇 |
排序方式: 共有941条查询结果,搜索用时 234 毫秒
61.
62.
63.
Chromosome numbers are reported for nearly 300 collections of Umbelliferae. Of these, 150 representing “new” or variant counts are figured. Karyotypes of fifteen of the genera included have apparently not been documented before. 相似文献
64.
65.
Ya‐Qian Zhang Yaosen Tian Yihan Xiao Lincoln J. Miara Yuichi Aihara Tomoyuki Tsujimura Tan Shi M. C. Scott Gerbrand Ceder 《Liver Transplantation》2020,10(27)
The interfacial instability between a thiophosphate solid electrolyte and oxide cathodes results in rapid capacity fade and has driven the need for cathode coatings. In this work, the stability, evolution, and performance of uncoated, Li2ZrO3‐coated, and Li3B11O18‐coated LiNi0.5Co0.2Mn0.3O2 cathodes are compared using first‐principles computations and electron microscopy characterization. Li3B11O18 is identified as a superior coating that exhibits excellent oxidation/chemical stability, leading to substantially improved performance over cells with Li2ZrO3‐coated or uncoated cathodes. The chemical and structural origin of the different performance is interpreted using different microscopy techniques which enable the direct observation of the phase decomposition of the Li2ZrO3 coating. It is observed that Li is already extracted from the Li2ZrO3 in the first charge, leading to the formation of ZrO2 nanocrystallites with loss of protection of the cathode. After 50 cycles separated (Co, Ni)‐sulfides and Mn‐sulfides can be observed within the Li2ZrO3‐coated material. This work illustrates the severity of the interfacial reactions between a thiophosphate electrolyte and oxide cathode and shows the importance of using coating materials that are absolutely stable at high voltage. 相似文献
66.
Fred Bernardes Filho Jaci Maria Santana Regina Coeli Palma de Almeida Glauber Voltan Natlia Aparecida de Paula Marcel Nani Leite Claudia Maria Lincoln Silva Camila Tormena Lean Basoli Joelma Menezes Moises Batista da Silva John Stewart Spencer Wilson Marques Jr Norma Tiraboschi Foss Marco Andrey Cipriani Frade 《PLoS neglected tropical diseases》2020,14(12)
BackgroundThis study evaluates an active search strategy for leprosy diagnosis based on responses to a Leprosy Suspicion Questionnaire (LSQ), and analyzing the clinical, immunoepidemiological and follow-up aspects for individuals living in a prison population.MethodsA cross-sectional study based on a questionnaire posing 14 questions about leprosy symptoms and signs that was distributed to 1,400 prisoners. This was followed by dermatoneurological examination, anti-PGL-I serology and RLEP-PCR. Those without leprosy were placed in the Non-leprosy Group (NLG, n = 1,216) and those diagnosed with clinical symptoms of leprosy were placed in the Leprosy Group (LG, n = 34).FindingsIn total, 896 LSQ were returned (64%), and 187 (20.9%) of the responses were deemed as positive for signs/symptoms, answering 2.7 questions on average. Clinically, 1,250 (89.3%) of the prisoners were evaluated resulting in the diagnosis of 34 new cases (LG), based on well-accepted clinical signs and symptoms, a new case detection rate of 2.7% within this population, while the NLG were comprised of 1,216 individuals. The confinement time medians were 39 months in the LG while it was 36 months in the NLG (p>0.05). The 31 leprosy cases who responded to the questionnaire (LSQ+) had an average of 1.5 responses. The symptoms “anesthetized skin area” and “pain in nerves” were most commonly mentioned in the LG while “tingling, numbness in the hands/feet”, “sensation of pricks and needles”, “pain in nerves” and “spots on the skin” responses were found in more than 30% of questionnaires in the NLG. Clinically, 88.2% had dysesthetic macular skin lesions and 97.1% presented some peripheral nerve impairment, 71.9% with some degree of disability. All cases were multibacillary, confirming a late diagnosis. Anti-PGL-I results in the LG were higher than in the NLG (p<0.0001), while the RLEP-PCR was positive in 11.8% of the patients.InterpretationOur findings within the penitentiary demonstrated a hidden prevalence of leprosy, although the individuals diagnosed were likely infected while living in their former communities and not as a result of exposure in the prison. The LSQ proved to be an important screening tool to help identify leprosy cases in prisons. 相似文献
67.
Cristian Koepfli Lincoln Timinao Tiago Antao Alyssa E. Barry Peter Siba Ivo Mueller Ingrid Felger 《PloS one》2013,8(6)
Introduction
The importance of Plasmodium vivax in malaria elimination is increasingly being recognized, yet little is known about its population size and population genetic structure in the South Pacific, an area that is the focus of intensified malaria control.Methods
We have genotyped 13 microsatellite markers in 295 P. vivax isolates from four geographically distinct sites in Papua New Guinea (PNG) and one site from Solomon Islands, representing different transmission intensities.Results
Diversity was very high with expected heterozygosity values ranging from 0.62 to 0.98 for the different markers. Effective population size was high (12′872 to 19′533 per site). In PNG population structuring was limited with moderate levels of genetic differentiation. F ST values (adjusted for high diversity of markers) were 0.14–0.15. Slightly higher levels were observed between PNG populations and Solomon Islands (F ST = 0.16).Conclusions
Low levels of population structure despite geographical barriers to transmission are in sharp contrast to results from regions of low P. vivax endemicity. Prior to intensification of malaria control programs in the study area, parasite diversity and effective population size remained high. 相似文献68.
Lenno van den Berg Catherine M. Kirkland Joseph D. Seymour Sarah L. Codd Mark C. M. van Loosdrecht Merle K. de Kreuk 《Biotechnology and bioengineering》2020,117(12):3809-3819
Aerobic granular sludge (AGS) technology allows simultaneous nitrogen, phosphorus, and carbon removal in compact wastewater treatment processes. To operate, design, and model AGS reactors, it is essential to properly understand the diffusive transport within the granules. In this study, diffusive mass transfer within full-scale and lab-scale AGS was characterized with nuclear magnetic resonance (NMR) methods. Self-diffusion coefficients of water inside the granules were determined with pulsed-field gradient NMR, while the granule structure was visualized with NMR imaging. A reaction-diffusion granule-scale model was set up to evaluate the impact of heterogeneous diffusion on granule performance. The self-diffusion coefficient of water in AGS was ∼70% of the self-diffusion coefficient of free water. There was no significant difference between self-diffusion in AGS from full-scale treatment plants and from lab-scale reactors. The results of the model showed that diffusional heterogeneity did not lead to a major change of flux into the granule (<1%). This study shows that differences between granular sludges and heterogeneity within granules have little impact on the kinetic properties of AGS. Thus, a relatively simple approach is sufficient to describe mass transport by diffusion into the granules. 相似文献
69.
70.
Amanda Linkous Demosthenes Balamatsias Matija Snuderl Lincoln Edwards Ken Miyaguchi Teresa Milner Batsheva Reich Leona Cohen-Gould Andrew Storaska Yasumi Nakayama Emily Schenkein Richa Singhania Stefano Cirigliano Tarig Magdeldin Ying Lin Gouri Nanjangud Kalyani Chadalavada David Pisapia Howard A. Fine 《Cell reports》2019,26(12):3203-3211.e5