全文获取类型
收费全文 | 490篇 |
免费 | 33篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 14篇 |
2020年 | 13篇 |
2019年 | 9篇 |
2018年 | 16篇 |
2017年 | 14篇 |
2016年 | 16篇 |
2015年 | 25篇 |
2014年 | 26篇 |
2013年 | 24篇 |
2012年 | 45篇 |
2011年 | 46篇 |
2010年 | 30篇 |
2009年 | 22篇 |
2008年 | 22篇 |
2007年 | 31篇 |
2006年 | 22篇 |
2005年 | 28篇 |
2004年 | 11篇 |
2003年 | 21篇 |
2002年 | 14篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1920年 | 1篇 |
排序方式: 共有523条查询结果,搜索用时 15 毫秒
91.
Turning the tables of sex distinction in craniofacial identification: Why females possess thicker facial soft tissues than males,not vice versa 下载免费PDF全文
Carl N. Stephan Rory Preisler Ozgur Bulut Mike Bennett 《American journal of physical anthropology》2016,161(2):283-295
Males are universally reported to possess larger facial soft‐tissue thickness (FSTT) than females, however, this observation oversimplifies the raw data yielding an underpowered assessment of FSTT sex‐patterning where: differences are small (η2 < 5%) and inconsistent (females are routinely larger than males at the cheeks). Here we investigate body‐size normalized data to assess whether more general and improved understanding of FSTT sex‐variation in humans is possible. FSTTs were measured in 52 healthy living Australians aged 18 to 30 years using B‐mode ultrasound. Participants' stature and body mass were also measured. Sex differences were calculated before and after normalization by the aforementioned body‐composition variables. Methods were repeated in three other independent samples to evaluate reproducibility: 100 American Whites and 60 American Blacks measured by B‐mode ultrasound; and 50 Turkish residents measured by regular supine CT. Compared to raw mean differences (F < M, by ?6%), females displayed much thicker FSTTs than males when normalized for body mass (F > M, by +16%). Consequently, while the sexes share similar raw values, females possess much larger FSTTs for their relatively lighter bodies. The relative FSTT difference was 2.7× larger than the raw mean difference. Sex differences in FSTT are of larger magnitude and reversed direction in mass normalized data. Contrary to popular thought, females possess much larger FSTTs than males owing to their generically lighter bodies (?18 kg). These data patterns help explain why the pooling of sex‐categorized FSTT does not jeopardize the sex‐difference—it is encoded more strongly in terms relative to body mass. 相似文献
92.
Fiona Bragg Liming Li Ling Yang Yu Guo Yiping Chen Zheng Bian Junshi Chen Rory Collins Richard Peto Chunmei Wang Caixia Dong Rong Pan Jinyi Zhou Xin Xu Zhengming Chen China Kadoorie Biobank collaborative group 《PLoS medicine》2016,13(7)
BackgroundIn China, diabetes prevalence is rising rapidly, but little is known about the associated risks and population burden of cardiovascular diseases. We assess associations of diabetes with major cardiovascular diseases and the relevance of diabetes duration and other modifiable risk factors to these associations.ConclusionsAmong Chinese adults, diabetes is associated with significantly increased risks of major cardiovascular diseases. The increasing prevalence and younger age of onset of diabetes foreshadow greater diabetes-attributable disease burden in China. 相似文献
93.
Sarah H. Wild Janet Hanley Stephanie C. Lewis John A. McKnight Lucy B. McCloughan Paul L. Padfield Richard A. Parker Mary Paterson Hilary Pinnock Aziz Sheikh Brian McKinstry 《PLoS medicine》2016,13(7)
BackgroundSelf-monitoring of blood glucose among people with type 2 diabetes not treated with insulin does not appear to be effective in improving glycemic control. We investigated whether health professional review of telemetrically transmitted self-monitored glucose results in improved glycemic control in people with poorly controlled type 2 diabetes.ConclusionsSupported telemonitoring resulted in clinically important improvements in control of glycaemia in patients with type 2 diabetes in family practice. Current Controlled Trials, registration number ISRCTN71674628.
Trial Registration
Current Controlled Trials ISRCTN 71674628 相似文献94.
Daniel Padfield Genevieve Yvon‐Durocher Angus Buckling Simon Jennings Gabriel Yvon‐Durocher 《Ecology letters》2016,19(2):133-142
Understanding the mechanisms that determine how phytoplankton adapt to warming will substantially improve the realism of models describing ecological and biogeochemical effects of climate change. Here, we quantify the evolution of elevated thermal tolerance in the phytoplankton, Chlorella vulgaris. Initially, population growth was limited at higher temperatures because respiration was more sensitive to temperature than photosynthesis meaning less carbon was available for growth. Tolerance to high temperature evolved after ≈ 100 generations via greater down‐regulation of respiration relative to photosynthesis. By down‐regulating respiration, phytoplankton overcame the metabolic constraint imposed by the greater temperature sensitivity of respiration and more efficiently allocated fixed carbon to growth. Rapid evolution of carbon‐use efficiency provides a potentially general mechanism for thermal adaptation in phytoplankton and implies that evolutionary responses in phytoplankton will modify biogeochemical cycles and hence food web structure and function under warming. Models of climate futures that ignore adaptation would usefully be revisited. 相似文献
95.
96.
97.
98.
Dietary salt intake and urinary sodium excretion were compared in normotensive and hypertensive subjects in Renfrew, Scotland. All groups had high 24-hour urinary salt excretions, and hypertensive subjects did not eat or excrete more salt than normotensive subjects. The only significant relations found were a lower sodium excretion in hypertensive women than in normotensive women (p < 0.02) and a lower urinary sodium concentration in hypertensive men than in normotensive men (p < 0.05). These data provide no support for the hypothesis that dietary salt is a major cause of hypertension. 相似文献
99.
Rory Pruitt Nidhish Sasi Michael L. Freeman Konjeti R. Sekhar 《Bioorganic & medicinal chemistry letters》2010,20(20):5997-6000
Radiation sensitization is significantly increased by proteotoxic stress, such as a heat shock. We undertook an investigation, seeking to identify natural products that induced proteotoxic stress and then determined if a compound exhibited radiosensitizing properties. The hydroxychalcones, 2′,5′-dihydroxychalcone (D-601) and 2,2′-dihydroxychalcone (D-501), were found to activate heat shock factor 1 (Hsf1) and exhibited radiation sensitization properties in colon and pancreatic cancer cells. The radiosensitization ability of D-601 was blocked by pretreatment with α-napthoflavone (ANF), a specific inhibitor of cytochrome P450 1A2 (CYP1A2), suggesting that the metabolite of D-601 is essential for radiosensitization. The study demonstrated the ability of hydroxychalcones to radiosensitize cancer cells and provides new leads for developing novel radiation sensitizers. 相似文献
100.
Onchocerca volvulus and Mansonella ozzardi are two human filarial parasites present in South and Central America. In the Brazilian Amazonia they are found in sympatry, and the lack of clear morphological diagnostic characters in the microfilariae hinders their identification. The major sperm protein (MSP) gene of both species has been sequenced and characterised to determine its potential as a molecular diagnostic character. The length of the MSP gene is different in each species, and this could be used to detect and differentiate them by running the polymerase chain reaction (PCR) product in an agarose gel. Two major gene groups were identified in O. volvulus with a genetic distance of 6% between them. In M. ozzardi only one major group of genes was observed. The high similarity between the protein amino acid sequence of both filarial species confirms that the MSP has been highly conserved through nematode evolution. 相似文献