全文获取类型
收费全文 | 1467936篇 |
免费 | 140557篇 |
国内免费 | 1427篇 |
出版年
2021年 | 18065篇 |
2019年 | 16286篇 |
2018年 | 18247篇 |
2017年 | 17019篇 |
2016年 | 28701篇 |
2015年 | 42902篇 |
2014年 | 50995篇 |
2013年 | 77663篇 |
2012年 | 41237篇 |
2011年 | 30376篇 |
2010年 | 44918篇 |
2009年 | 45944篇 |
2008年 | 28525篇 |
2007年 | 26893篇 |
2006年 | 31528篇 |
2005年 | 32396篇 |
2004年 | 31553篇 |
2003年 | 28939篇 |
2002年 | 26916篇 |
2001年 | 39431篇 |
2000年 | 37372篇 |
1999年 | 35593篇 |
1998年 | 26151篇 |
1997年 | 26129篇 |
1996年 | 25666篇 |
1995年 | 23820篇 |
1994年 | 23635篇 |
1993年 | 22803篇 |
1992年 | 31045篇 |
1991年 | 29653篇 |
1990年 | 28308篇 |
1989年 | 28735篇 |
1988年 | 26594篇 |
1987年 | 25320篇 |
1986年 | 24158篇 |
1985年 | 26055篇 |
1984年 | 25214篇 |
1983年 | 22303篇 |
1982年 | 22065篇 |
1981年 | 21348篇 |
1980年 | 19855篇 |
1979年 | 21845篇 |
1978年 | 19938篇 |
1977年 | 18966篇 |
1976年 | 18070篇 |
1975年 | 17930篇 |
1974年 | 18349篇 |
1973年 | 18630篇 |
1972年 | 16176篇 |
1971年 | 14565篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
591.
592.
593.
Factors affecting equal catchability in two swallowtail butterflies, Papilio polyxenes and P.glaucus 总被引:1,自引:0,他引:1
ROBERT C. LEDERHOUSE 《Ecological Entomology》1982,7(4):379-383
Abstract. 1. Recapture probabilities were analysed for individually marked black swallowtails, Papilio polyxenes F., and tiger swallowtails, P.glaucus L. (Lepidoptera: Papilionidae).
2. Recapture rates differed with sex and behaviour at time of capture for P.polyxenes , but not with age. For P.glaucus , only differences related to behaviour at time of capture were significant.
3. Black swallowtail males that were not physically restrained in identification had a recapture probability (73%) that was significantly higher than the 45% for males that were captured and handled. The higher rate was also exhibited by released, laboratory-reared males.
4. The capture effect was due to increased dispersal out of the areas and not to avoidance of capture or the capture site. 相似文献
2. Recapture rates differed with sex and behaviour at time of capture for P.polyxenes , but not with age. For P.glaucus , only differences related to behaviour at time of capture were significant.
3. Black swallowtail males that were not physically restrained in identification had a recapture probability (73%) that was significantly higher than the 45% for males that were captured and handled. The higher rate was also exhibited by released, laboratory-reared males.
4. The capture effect was due to increased dispersal out of the areas and not to avoidance of capture or the capture site. 相似文献
594.
Conformational similarity among amino acid residues, a property derived by analysing (φ, ψ)-probability distributions of 20 proteinous amino acids from 38 different globular proteins, is used to arrive at a set of six ‘obligatory’ amino acids of primitive proteins. The amino acids Ser, Val, Leu, Asp, Gly and Pro have been argued to be ‘obligatory’ and to represent, conformationally, the remaining amino acids. The reasons for consideration of these six residues as ‘obligatory’ are discussed. Methods to check the validity of our proposition are suggested. 相似文献
595.
596.
In C4 plants phosphoenolpyruvate (PEP) of the C4 cycle may betransported on a chloroplast transporter which also transports3-phosphoglycerate (3-PGA) and triosephosphates. In C3 plantsPEP is not considered to be effectively transported on the chloroplastphosphate translocator. The influences of certain organic phosphates,having a similar structure to either PEP or triose-phosphates,on 3-PGA dependent O2 evolution by C4 (Digitaria sanquinalisL. Scop.) and C3 (Hordeum vulgare L.) mesophyll chloroplastswere investigated. In the C4 mesophyll chloroplasts phosphoglycolatewas a competitive inhibitor (Ki = 2.1 mM) of 3-PGA dependentO2 evolution, and was as effective as previously reported forPEP. 2-Phosphoglycerate was also a competitive inhibitor (Kt= 8.6 mM) of O2 evolution in the C4 mesophyll chloroplasts with3-PGA as substrate, while phospholactate was a weak inhibitorand glyphosate had no effect. Neither PEP, phosphoglycolatenor 2-phosphoglycerate were effective inhibitors of 3- PGA dependentO2 evolution in the C3 chloroplasts. Phosphohydroxypyruvatewas a competitive inhibitor of 3-PGA dependent O22 evolutionin both chloroplast types. The selectivity in inhibition ofO2 evolution with 3-PGA as substrate suggests that the C4 mesophyllchloroplasts can recognize certain organic phosphates with thephosphate in the C-2 or C-3 position but that the C4 mesophyllchloroplasts can only effectively recognize certain organicphosphates with the phosphate in the C-3 position. The resultsalso support the view that 3-PGA and PEP are transported onthe same phosphate translocator in C4 mesophyll chloroplasts.
1 Current address: Department of Horticulture, 2001 Fyffe Court,The Ohio State University, Columbus, Ohio 43210-1096. (Received March 24, 1987; Accepted April 16, 1987) 相似文献
597.
598.
599.
600.
J R van Der Ploeg R Iwanicka-Nowicka T Bykowski M M Hryniewicz T Leisinger 《The Journal of biological chemistry》1999,274(41):29358-29365