全文获取类型
收费全文 | 743篇 |
免费 | 58篇 |
国内免费 | 2篇 |
专业分类
803篇 |
出版年
2024年 | 4篇 |
2023年 | 11篇 |
2022年 | 22篇 |
2021年 | 31篇 |
2020年 | 26篇 |
2019年 | 30篇 |
2018年 | 40篇 |
2017年 | 21篇 |
2016年 | 29篇 |
2015年 | 34篇 |
2014年 | 50篇 |
2013年 | 40篇 |
2012年 | 52篇 |
2011年 | 67篇 |
2010年 | 29篇 |
2009年 | 30篇 |
2008年 | 28篇 |
2007年 | 19篇 |
2006年 | 20篇 |
2005年 | 19篇 |
2004年 | 20篇 |
2003年 | 19篇 |
2002年 | 21篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1992年 | 5篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1981年 | 4篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1976年 | 4篇 |
1975年 | 6篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1969年 | 4篇 |
1968年 | 2篇 |
1967年 | 4篇 |
1966年 | 2篇 |
1965年 | 4篇 |
1964年 | 2篇 |
排序方式: 共有803条查询结果,搜索用时 15 毫秒
161.
Background
There are no drugs presently available to treat traumatic brain injury (TBI). A variety of single drugs have failed clinical trials suggesting a role for drug combinations. Drug combinations acting synergistically often provide the greatest combination of potency and safety. The drugs examined (minocycline (MINO), N-acetylcysteine (NAC), simvastatin, cyclosporine A, and progesterone) had FDA-approval for uses other than TBI and limited brain injury in experimental TBI models.Methodology/Principal Findings
Drugs were dosed one hour after injury using the controlled cortical impact (CCI) TBI model in adult rats. One week later, drugs were tested for efficacy and drug combinations tested for synergy on a hierarchy of behavioral tests that included active place avoidance testing. As monotherapy, only MINO improved acquisition of the massed version of active place avoidance that required memory lasting less than two hours. MINO-treated animals, however, were impaired during the spaced version of the same avoidance task that required 24-hour memory retention. Co-administration of NAC with MINO synergistically improved spaced learning. Examination of brain histology 2 weeks after injury suggested that MINO plus NAC preserved white, but not grey matter, since lesion volume was unaffected, yet myelin loss was attenuated. When dosed 3 hours before injury, MINO plus NAC as single drugs had no effect on interleukin-1 formation; together they synergistically lowered interleukin-1 levels. This effect on interleukin-1 was not observed when the drugs were dosed one hour after injury.Conclusions/Significance
These observations suggest a potentially valuable role for MINO plus NAC to treat TBI. 相似文献162.
Emam ElHak Abdel Fatah Natalie R. Shirley Mohamed R. Mahfouz Benjamin M. Auerbach 《American journal of physical anthropology》2012,149(4):547-559
This study presents a novel three‐dimensional analysis using statistical atlases and automated measurements to assess diaphyseal morphology of the clavicle and its relationship to muscle asymmetry. A sample of 505 individuals (285 males, 220 females) from the William McCormick Clavicle Collection was CT scanned, segmented, and added to a statistical bone atlas that captures correspondence between homologous points on the bone surfaces. Muscle attachment sites were localized on the atlas and then propagated across the entire population. Cross‐sectional contours were extracted at 5% increments along the entire bone, as well as at muscle attachment sites and the clavicle waist; maximum and minimum dimensions of each cross‐sectional contour were calculated. In addition, the entire three‐dimensional surface was examined for asymmetry by analyzing the magnitude and directional differences between homologous points across all bone surfaces in the dataset. The results confirm the existing studies on clavicle asymmetry, namely that the left clavicle is longer than the right, but the right is more robust than the left. However, the patterns of asymmetry are sexually dimorphic. Males are significantly asymmetric in all dimensions and at muscle and ligament attachment sites (P < 0.05), whereas female asymmetry is more variable. We hypothesize that this is related to absolute and relative differences in male muscle strength compared to females. However, an area with no muscle attachments on the posterior midshaft was significantly asymmetric in both sexes. We suggest that this is a curvature difference caused by opposing muscle actions at the medial and lateral ends of the bone. Am J Phys Anthropol 2012. © 2012 Wiley Periodicals, Inc. 相似文献
163.
Biomonitoring of the Genotoxic and Hepatotoxic Effects and Oxidative Stress Potentials of Itraconazole in Pregnant Rats 下载免费PDF全文
164.
165.
166.
Because metals can produce health risks, standards for regulating metal exposure are necessary. The purpose of this chapter is to review the application of uncertainty factors to mercury, arsenic, and cadmium. By the conventional method, uncertainty factors are often applied to animal studies to establish the reference dose (RfD) in humans. However, with the availability of a better database from improved study designs, it was demonstrated that uncertainty factors can be decreased. Incorporation of more pharmacokinetic and mechanistic data into the risk assessment process, as well as discussions between risk assessors and the research community to identify research needs are essential in reducing uncertainty factors. 相似文献
167.
Abdel Samie Elewa 《Hydrobiologia》1985,128(3):249-254
The cyclic annual flood reaching Aswan High Dam Reservoir, results in a gradual increase in water level. However, the impacts of this incoming water mass are not merely the increase in water level, but also change the physical and chemical characteristics of the reservoir. The flood water coming from the south is rich in suspended matter, which gradually sediment to the bottom. The highest values of total dissolved solids and electrical conductance can be measured just in front of the edge of the flood. 相似文献
168.
Roots and aerial shoots ofZygophyllum coccineum L.,Z. album L. andZ. dumosum Boiss were extracted with solvents of increasing polarity and tested against spore germination ofVerticellium albo-atrum andFusarium oxysporum f.sp.lycopersici. The effectiveness of each extract depends on the solvent, plant species, organ and test fungus. Petroleum ether extracts
were ineffective as fungistatics while the methanol extracts possessed a high inhibitory effect toward spore germination suppression,
depending on the fungus and plant species. Water or ethyl acetate root extracts ofZ. album caused a marked suppression of spore germination of the test fungi. Six saponins were isolated from the effective extracts
on silica gel and Sephadex columns. They were identified by acid hydrolysis, alkaline saponification, IR and FAB MS. Quinovic
acid was the dominant aglycone. Kaempferol was isolated from the flavonoid fraction ofZ. dumosum for the first time. Some of the isolated saponins and kaempferol provided successful control against the test plant pathogens
under greenhouse experiment when used as seed treatment. 相似文献
169.
The influence of mounting and ejaculation on the FSH, LH and testosterone secretory patterns was studied in three azoospermic (including one 61 XXY; one Sertoli-cell-only Syndrome and one secretory-excretory azoospermic) and three control normospermic bulls. Sexual activity did not result in any alteration in the release of these three hormones. There was no difference between the secretory patterns before and after ejaculation in the two classes of bulls. One of the main features was the elevated concentrations of FSH in the bull with Klinefelter's Syndrome, but the mounting test did not result in any significant effect on this concentration. The LH and testosterone patterns were similar for all individuals. From these results, it can be concluded that the mounting test applied under these experimental conditions had no effect on the pituitary-gonadal axis in bulls characterized by either impairment of spermatogenesis or normal semen production. 相似文献
170.