全文获取类型
收费全文 | 102篇 |
免费 | 16篇 |
出版年
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 6篇 |
2014年 | 12篇 |
2013年 | 6篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 8篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 3篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1975年 | 3篇 |
1971年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有118条查询结果,搜索用时 15 毫秒
111.
Hubert Josien David Bom Dennis P. Curran Yu-Huang Zheng Ting-Chao Chou 《Bioorganic & medicinal chemistry letters》1997,7(24):1574-3194
The synthesis and biological evaluation of about one dozen 7-silylcamptothecin derivatives are described. Most new compounds show potencies comparable to or better than camptothecin itself. The best compound, 11-fluoro-10-amino-7-trimethylsilylcamptothecin, is more than 20 times more potent than camptothecin in cell assays. 相似文献
112.
Veruska Nogueira de Brito Arleana do Bom Parto Ferreira de Almeida Luciano Nakazato Rosemere Duarte Cladson de Oliveira Souza Valéria Régia Franco Sousa 《Memórias do Instituto Oswaldo Cruz》2014,109(7):899-904
Visceral leishmaniasis (VL) in Brazil is transmitted by the phlebotomine
Lutzomyia longipalpis and in some midwestern regions by
Lutzomyia cruzi. Studies of the phlebotomine fauna, feeding
habits and natural infection rate by Leishmania contribute to
increased understanding of the epidemiological chain of leishmaniases and their
vectorial capacity. Collections were performed in Jaciara, state of Mato Grosso from
2010-2013, during which time 2,011 phlebotomines (23 species) were captured (68.70%
Lu. cruzi and 20.52% Lutzomyia whitmani).
Lu. cruzi females were identified by observing the shapes of the
cibarium (a portion of the mouthpart) and spermatheca, from which samples were
obtained for polymerase chain reaction to determine the rates of natural infection.
Engorged phlebotomines were assessed to identify the blood-meal host by ELISA. A
moderate correlation was discovered between the number of Lu. cruzi
and the temperature and the minimum rate of infection was 6.10%. Twenty-two females
were reactive to the antisera of bird (28%), dog (3.30%) and skunk (1.60%). We
conclude that Lu. cruzi and Lu. whitmani have
adapted to the urban environment in this region and that Lu. cruzi
is the most likely vector of VL in Jaciara. Moreover, maintenance of
Leishmania in the environment is likely aided by the presence of
birds and domestic and synanthropic animals. 相似文献
113.
114.
Jan-Paul W R Roovers Johanna G van der Bom C Huub van der Vaart A Peter M Heintz 《BMJ (Clinical research ed.)》2003,327(7418):774-778
Objectives To compare the effects of vaginal hysterectomy, subtotal abdominal hysterectomy, and total abdominal hysterectomy on sexual wellbeing.Design Prospective observational study over six months.Setting 13 teaching and non-teaching hospitals in the Netherlands.Participants 413 women who underwent hysterectomy for benign disease other than symptomatic prolapse of the uterus and endometriosis.Main outcome measures Reported sexual pleasure, sexual activity, and bothersome sexual problems.Results Sexual pleasure significantly improved in all patients, independent of the type of hysterectomy. The prevalence of one or more bothersome sexual problems six months after vaginal hysterectomy, subtotal abdominal hysterectomy, and total abdominal hysterectomy was 43% (38/89), 41% (31/76), and 39% (57/145), respectively (χ2 test, P = 0.88).Conclusion Sexual pleasure improves after vaginal hysterectomy, subtotal abdominal hysterectomy, and total abdominal hysterectomy. The persistence and development of bothersome problems during sexual activity were similar for all three techniques. 相似文献
115.
116.
Long-term fertilisation strategies and form affect nutrient budgets and soil test values,soil carbon retention and crop yield resilience 总被引:1,自引:0,他引:1
Plant and Soil - The aim of this study was to evaluate the effects of long-term mineral and organic fertilisation on crop performance and soil fertility. The Long-Term Nutrient Depletion Trial... 相似文献
117.
118.
We examined annual variation in the timing of conception andparturition in the African buffalo (Syncerus caffer) and thesynchrony of birth timing with resource cues, using 8 yearsof monthly birth, rainfall, and vegetation data, measured asNormalized Difference Vegetation Index (NDVI). Monthly birthshad the strongest significant correlations with NDVI and rainfalllevels 12 and 13 months in the past, respectively. In addition,the synchrony of current year births corresponds most stronglyto the synchrony of the previous year's NDVI distribution. Becausethe gestation period of buffalo has been estimated to be around11 months, these findings suggest that improved protein levels,occurring approximately a month after the first green flushof the wet season, are either a trigger for conception or conceptionhas evolved to be synchronous with correlated environmentalcues that ensure females enter a period of peak body conditionaround the time of conception and/or parturition. With a gestationperiod of approximately 340 days, parturition occurs to takeadvantage of the period when forage has its highest proteincontent. A comparative analysis of gestation periods withinthe subfamily Bovinae indicates that African buffalo have aprotracted gestation for their body size, which we suggest isan adaptation to their seasonal environment. We also found thatinterannual variation in the birth distribution suggests a degreeof plasticity in the date of conception, and variation in thenumber of calves born each year suggest further synchrony ata timescale longer than a single year. 相似文献