全文获取类型
收费全文 | 1831篇 |
免费 | 135篇 |
国内免费 | 6篇 |
出版年
2023年 | 7篇 |
2022年 | 18篇 |
2021年 | 45篇 |
2020年 | 23篇 |
2019年 | 40篇 |
2018年 | 42篇 |
2017年 | 42篇 |
2016年 | 46篇 |
2015年 | 97篇 |
2014年 | 92篇 |
2013年 | 103篇 |
2012年 | 144篇 |
2011年 | 129篇 |
2010年 | 79篇 |
2009年 | 63篇 |
2008年 | 86篇 |
2007年 | 67篇 |
2006年 | 66篇 |
2005年 | 59篇 |
2004年 | 47篇 |
2003年 | 60篇 |
2002年 | 48篇 |
2001年 | 37篇 |
2000年 | 36篇 |
1999年 | 33篇 |
1998年 | 16篇 |
1997年 | 19篇 |
1996年 | 16篇 |
1995年 | 17篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 37篇 |
1991年 | 23篇 |
1990年 | 14篇 |
1989年 | 23篇 |
1988年 | 24篇 |
1987年 | 38篇 |
1986年 | 25篇 |
1985年 | 14篇 |
1984年 | 22篇 |
1983年 | 26篇 |
1982年 | 9篇 |
1981年 | 16篇 |
1980年 | 13篇 |
1979年 | 16篇 |
1978年 | 9篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1973年 | 8篇 |
1972年 | 12篇 |
排序方式: 共有1972条查询结果,搜索用时 250 毫秒
1.
2.
3.
4.
Satish Malik 《Carbohydrate research》2010,345(7):867-57
Treatment of peracetylated alkyl and aryl 1,2-trans-glycosides with iodine in the presence of HMDS has been found to result in the anomerization leading to the formation of the respective 1,2-cis-glycosides. In the case of alkyl glycosides with aglycons of short alkyl chain length complete anomerization to the α-glycosides was observed while with those of longer chain length the process was found to be incomplete. The observations have been interpreted mechanistically. 相似文献
5.
Osmotic priming of aged onion seeds with 25% polyethylene glycol-8000 for 5 d resulted in a marked increase in the rate of
germination and early seedling growth. Priming reduced electrolyte leakage as well as lipid peroxidation in seeds implying
the activation of membrane repair processes. Priming was also associated with increased levels of antioxidants,i.e. ascorbic acid and tocopherols particularly the latter and the activities of catalase and peroxidase involved in the mitigation
of oxidative damage. In comparison with the priming of unaged seeds, the aged seeds experienced a diminution of response in
terms of changes in the levels of antioxidants and scavenging enzymes. 相似文献
6.
7.
AbstractCircadian rhythms are endogenous, and synchronize biological functions at the most suited time of the day. Insects like other organism display a wide array of circadian functions, which are controlled by a central timing system, in coordination with the peripheral clocks found in many tissues. Many insect behaviours including locomotion, courtship, mating, egg laying and photoperiodism, are influenced by the circadian systems. In this mini-review, we briefly describe the involvement of circadian clocks in various physiological processes and correlate their functions in insect life, focusing on lepidopteran pests (major group of Indian crop pests) and discuss their role(s) in the development of effective pest management strategy. 相似文献
8.
DA/DAPI heteromorphisms in acrocentric chromosomes other than 15 总被引:1,自引:0,他引:1
9.
10.
We studied the effects of the CuZn superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) on endothelial permeability to 125I-albumin after activation of neutrophils (PMN) with phorbol 12-myristate-13-acetate (PMA; 10?8M). PMN were either in direct contact with the endothelial cell monolayer grown on a porous gelatin-coated microporous 10-μm-thick polycarbonate filter (upright system) or separated from the endothelium by a similar filter (inverted system). Transendothelial 125I-albumin clearance rates were measured as an index of endothelial permeability. In the absence of antioxidants, activation of PMN increased transendothelial 125I-albumin clearnace rates in both systems from 0.041 ± 0.006 μl/min (baseline) to 0.262 ± 0.18 μl/min (upright system) and from 0.063 ± 0.02 μl/min to 0.244 ± 0.06 μl/min (inverted system). PMA induced 80–90% of PMN to adhere to either gelatin-coated filters or to endothelial cells, from the basal PMN adhesion value of 5.3 ± 2.2% and 4.3 ± 1.1%, respectively. SOD, which dismutates superoxide anion to hydrogen peroxide (H2O2), did not alter the transendothelial 125I-albumin clearance rates in either systm at any concerntration from 10–300 U/ml. CAT (100–1,000 U/ml) and GSH (0.5–10 mM), which remove the H2O2 generated during PMN activation, did not alter the increase in transendothelial 125I-clearance rates after PMN activation in the upright system, but both agents prvented the increase in transendothelial 125I-clearance rates in the inverted system. We conclude that PMN activation with PMA causes endothelial injury irrespective of PMN contact to the endothelial monolayer. Moreover, H2O2, a release product of PMN activation, is a critical mediator of PMN-dependent endothelial injury. Finally, the results indicate that CAT and GSH prevent endothelial injury only in the absence of direct PMN contact with endothelial cells, suggesting that antioxidants such as GSH and CAT are excluded from sites of PMN-endothelial contact and thus are ineffective antioxidants. © 1993 Wiley-Liss, Inc. 相似文献