全文获取类型
收费全文 | 605篇 |
免费 | 111篇 |
专业分类
716篇 |
出版年
2021年 | 6篇 |
2020年 | 8篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 6篇 |
2015年 | 20篇 |
2014年 | 23篇 |
2013年 | 25篇 |
2012年 | 30篇 |
2011年 | 25篇 |
2010年 | 20篇 |
2009年 | 17篇 |
2008年 | 19篇 |
2007年 | 26篇 |
2006年 | 23篇 |
2005年 | 12篇 |
2004年 | 14篇 |
2003年 | 15篇 |
2002年 | 16篇 |
2001年 | 25篇 |
2000年 | 18篇 |
1999年 | 15篇 |
1998年 | 14篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 13篇 |
1993年 | 6篇 |
1992年 | 19篇 |
1991年 | 17篇 |
1989年 | 14篇 |
1988年 | 26篇 |
1987年 | 16篇 |
1986年 | 12篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1975年 | 5篇 |
1974年 | 11篇 |
1973年 | 9篇 |
1972年 | 10篇 |
1971年 | 6篇 |
1970年 | 7篇 |
1966年 | 5篇 |
排序方式: 共有716条查询结果,搜索用时 0 毫秒
51.
The aim of this 2-year longitudinal observational study was to explore hand bone loss as a disease outcome measure in established
rheumatoid arthritis (RA). 相似文献
52.
Screening by chlorophyll (Chl) affects photoconversion rates and photoequilibrium ratios of phytochrome in vivo and may cause distortion of the action spectra of photomorphogenesis (N Kazarinova-Fukshansky, M Seyfried, E Schäfer 1985 Photochem Photobiol 41: 689-702). Inhibitors that reduce the Chl content of seedlings are sometimes used in photomorphogenesis research to decrease the effects of Chl screening on the state of phytochrome in vivo. Streptomycin is one of the inhibitors that can be used for this purpose. The effects of streptomycin on phytochrome-mediated anthocyanin accumulation in young seedlings are significantly different in closely related systems. The use of `Chl-bleachers' in photomorphogenesis studies may produce undesirable side effects. At the level of the expression of a photoregulated response, the effects of differences in the state of phytochrome between water-grown Chl-rich and inhibitor-treated Chl-poor seedlings may be difficult to evaluate because they may be masked by the effects of the inhibitor on the response. 相似文献
53.
54.
55.
H F Hoff W A Bradley C L Heideman J W Gaubatz M D Karagas A M Gotto 《Biochimica et biophysica acta》1979,573(2):361-374
Physical and chemical criteria of lipoproteins containing apolipoprotein B, extracted from human aortic intima, were compared with those of plasma low density lipoproteins (LDL). Homogenates of grossly normal intima and advanced atherosclerotic lesions were subjected to differential ultracentrifugation to isolate a d = 1.006--1.063 g/ml density fraction which was extensively characterized. By electroimmunoassay, over 90% of the recovered apolipoprotein B immunological reactivity was found in isolates from both plaques and normal intima. In isolates of plaque and normal intima, particles of the same size as LDL were found, although a small population of very large structures was also present in plaque fractions. Apolipoprotein composition was similar to that of plasma LDL except for the presence of human serum albumin in aortic isolates. Fractions from aorta demonstrated greater electrophoretic mobilities than LDL. The lipid composition of isolates from normal intima was similar to that of LDL. The lipid composition of plaque fractions showed a significant decrease in the cholesteryl ester to free cholesterol ratio and in the triglyceride content in comparison to LDL and to fractions from normal intima. The fatty acid pattern of the cholesteryl ester fraction from isolates of both normal and plaque aortic homogenates demonstrated a significant decrease in the linoleate to oleate ratio as compared to LDL. Our initial studies suggest that althought aortic fractions are similar to LDL by certain criteria, some differences observed are more pronounced in fractions from lesions than from normal intima. 相似文献
56.
Roel W. Ten Broek Sander Grefte Johannes W. Von den Hoff 《Journal of cellular physiology》2010,224(1):7-16
Skeletal muscle regeneration is a complex process, which is not yet completely understood. Satellite cells, the skeletal muscle stem cells, become activated after trauma, proliferate, and migrate to the site of injury. Depending on the severity of the myotrauma, activated satellite cells form new multinucleated myofibers or fuse to damaged myofibers. The specific microenvironment of the satellite cells, the niche, controls their behavior. The niche contains several components that maintain satellite cells quiescence until they are activated. In addition, a great diversity of stimulatory and inhibitory growth factors such as IGF‐1 and TGF‐β1 regulate their activity. Donor‐derived satellite cells are able to improve muscle regeneration, but their migration through the muscle tissue and across endothelial layers is limited. Less than 1% of their progeny, the myoblasts, survive the first days upon intra‐muscular injection. However, a range of other multipotent muscle‐ and non‐muscle‐derived stem cells are involved in skeletal muscle regeneration. These stem cells can occupy the satellite cell niche and show great potential for the treatment of skeletal muscle injuries and diseases. The aim of this review is to discuss the niche factors, growth factors, and other stem cells, which are involved in skeletal muscle regeneration. Knowledge about the factors regulating satellite cell activity and skeletal muscle regeneration can be used to improve the treatment of muscle injuries and diseases. J. Cell. Physiol. 224:7–16, 2010 © 2010 Wiley‐Liss, Inc. 相似文献
57.
Martin Oheim Marcel van 't Hoff Anne Feltz Alsu Zamaleeva Jean-Maurice Mallet Mayeul Collot 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2014
Most chemical and, with only a few exceptions, all genetically encoded fluorimetric calcium (Ca2+) indicators (GECIs) emit green fluorescence. Many of these probes are compatible with red-emitting cell- or organelle markers. But the bulk of available fluorescent-protein constructs and transgenic animals incorporate green or yellow fluorescent protein (GFP and YFP respectively). This is, in part, not only heritage from the tendency to aggregate of early-generation red-emitting FPs, and due to their complicated photochemistry, but also resulting from the compatibility of green-fluorescent probes with standard instrumentation readily available in most laboratories and core imaging facilities. Photochemical constraints like limited water solubility and low quantum yield have contributed to the relative paucity of red-emitting Ca2+ probes compared to their green counterparts, too. The increasing use of GFP and GFP-based functional reporters, together with recent developments in optogenetics, photostimulation and super-resolution microscopies, has intensified the quest for red-emitting Ca2+ probes. In response to this demand more red-emitting chemical and FP-based Ca2+-sensitive indicators have been developed since 2009 than in the thirty years before. 相似文献
58.
Endonuclease III of Escherichia coli is normally involved in the repair of oxidative DNA damage. Here, we have investigated a possible role of EndoIII in the repair of alkylation damage because of its structural similarity to the alkylation repair enzyme 3-methyladenine DNA glycosylase II. It was found that overproduction of EndoIII partially relieved the alkylation sensitivity of alkA mutant cells. Site-directed mutagenesis to make the active site of EndoIII more similar to AlkA (K120W) had an adverse effect on the complementation and the mutant protein apparently inhibited repair by competing for the substrate without base release. These results suggest that EndoIII might replace AlkA in some aspect of alkylation repair, although high expression levels are needed to produce this effect. 相似文献
59.
Manikumar G Wadkins RM Bearss D Von Hoff DD Wani MC Wall ME 《Bioorganic & medicinal chemistry letters》2004,14(21):5377-5381
By developing a new synthetic procedure for introduction of side chains onto the camptothecin ring system, we were able to achieve the preparation of a number of analogs bearing bulky, hydrophobic groups directly attached to the 7-position. These include 7-tert-butylcamptothecin, 7-benzylcamptothecin and the corresponding 10,11-methylenedioxycamptothecins. This method involves the reaction of an appropriate orthoaminobenzonitrile with various Grignard reagents to give the corresponding orthoaminoketones. Friedlander condensation of the latter with the key tricyclic ketone leads to 7-substituted camptothecin analogs. We report the activity of these compounds as topoisomerase I poisons and their ability to inhibit growth of selected tumor cell lines. 相似文献
60.
The efficacy of teflubenzuron (Calicide) for the treatment of farmed Atlantic salmon Salmo salar L. infested with sea lice Lepeophtheirus salmonis (Kr?yer, 1838), was investigated at low water temperatures in 2 commercial salmon farms. Calicide, coated on commercial feed pellets, was administered orally at 10 mg kg(-1) d(-1) for 7 consecutive days. Fish were randomly sampled and lice numbers recorded from both treated and control groups on 3 or 4 sampling occasions post-medication. Statistically significant reductions in the number of L. salmonis per fish were recorded. Maximum efficacy was observed toward chalimus and preadult stages of L. salmonis, and was achieved approximately 26 d post-medication. No adverse drug reactions or palatability problems were associated with the treatments. 相似文献