全文获取类型
收费全文 | 997篇 |
免费 | 122篇 |
专业分类
1119篇 |
出版年
2022年 | 8篇 |
2021年 | 14篇 |
2019年 | 10篇 |
2018年 | 9篇 |
2017年 | 11篇 |
2016年 | 21篇 |
2015年 | 32篇 |
2014年 | 22篇 |
2013年 | 34篇 |
2012年 | 69篇 |
2011年 | 46篇 |
2010年 | 49篇 |
2009年 | 40篇 |
2008年 | 46篇 |
2007年 | 40篇 |
2006年 | 38篇 |
2005年 | 40篇 |
2004年 | 36篇 |
2003年 | 23篇 |
2002年 | 31篇 |
2001年 | 39篇 |
2000年 | 28篇 |
1999年 | 15篇 |
1998年 | 8篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 11篇 |
1994年 | 13篇 |
1993年 | 11篇 |
1992年 | 19篇 |
1991年 | 14篇 |
1990年 | 13篇 |
1989年 | 20篇 |
1988年 | 10篇 |
1987年 | 15篇 |
1986年 | 17篇 |
1985年 | 11篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 10篇 |
1979年 | 11篇 |
1978年 | 11篇 |
1977年 | 21篇 |
1974年 | 8篇 |
1973年 | 10篇 |
1972年 | 9篇 |
1970年 | 15篇 |
1968年 | 8篇 |
排序方式: 共有1119条查询结果,搜索用时 15 毫秒
11.
G. N. Harrington V. R. Franceschi C. E. Offler J. W. Patrick M. Tegeder W. B. Frommer J. F. Harper W. D. Hitz 《Protoplasma》1997,197(3-4):160-173
Summary In developing seeds ofVicia faba, transfer cells line the inner surface of the seed coat and the juxtaposed epidermal surface of the cotyledons. Circumstantial evidence, derived from anatomical and physiological studies, indicates that these cells are the likely sites of sucrose efflux to, and influx from, the seed apoplasm, respectively. In this study, expression of an H+/sucrose symporter-gene was found to be localised to the epidermal-transfer cell complexes of the cotyledons. The sucrose binding protein (SBP) gene was expressed in these cells as well as in the thin-walled parenchyma transfer cells of the seed coat. SBP was immunolocalised exclusively to the plasma membranes located in the wall ingrowth regions of the transfer cells. In addition, a plasma membrane H+-ATPase was most abundant in the wall ingrowth regions with decreasing levels of expression at increasing distance from the transfer cell layers. The observed co-localisation of high densities of a plasma membrane H+-ATPase and sucrose transport proteins to the wall ingrowths of the seed coat and cotyledon transfer cells provides strong evidence that these regions are the principal sites of facilitated membrane transport of sucrose to and from the seed apoplasm.Abbreviations BCIP
5-bromo-4-chloro-3-indolyl phosphate
- DIG
digoxigenin
- H+-ATPase
plasma membrane H+-translocating adenosine triphosphatase
- Ig
immunoglobulin
- LeSUT1
tomato H+/sucrose symporter
- SBP
sucrose binding protein 相似文献
12.
The Telomerase/vault-associated protein TEP1 is required for vault RNA stability and its association with the vault particle 总被引:7,自引:0,他引:7
Kickhoefer VA Liu Y Kong LB Snow BE Stewart PL Harrington L Rome LH 《The Journal of cell biology》2001,152(1):157-164
Vaults and telomerase are ribonucleoprotein (RNP) particles that share a common protein subunit, TEP1. Although its role in either complex has not yet been defined, TEP1 has been shown to interact with the mouse telomerase RNA and with several of the human vault RNAs in a yeast three-hybrid assay. An mTep1(-/-) mouse was previously generated which resulted in no apparent change in telomere length or telomerase activity in six generations of mTep1-deficient mice. Here we show that the levels of the telomerase RNA and its association with the telomerase RNP are also unaffected in mTep1(-/-) mice. Although vaults purified from the livers of mTep1(-/-) mice appear structurally intact by both negative stain and cryoelectron microscopy, three-dimensional reconstruction of the mTep1(-/-) vault revealed less density in the cap than previously observed for the intact rat vault. Furthermore, the absence of TEP1 completely disrupted the stable association of the vault RNA with the purified vault particle and also resulted in a decrease in the levels and stability of the vault RNA. Therefore, we have uncovered a novel role for TEP1 in vivo as an integral vault protein important for the stabilization and recruitment of the vault RNA to the vault particle. 相似文献
13.
14.
The removal of cobalt from cobalt(II) bovine carbonic anhydrase by pyridine-2-carboxylate, pyridine-2,6-dicarboxylate and 5-methyl-1,10-phenanthroline occurs via formation of an intermediate. This is presumed to be a ternary adduct of cobalt(II) enzyme with the ligand. In this, metal-protein bonds are loosened, probably via distortion of the normal geometry, resulting in accelerated breakdown of the adduct to apoprotein, compared with the behavior of the cobalt(II) enzyme alone. With 2-carboxy-1,10-phenanthroline, removal of metal is very rapid but no adduct is observed. Values of stability constants of the adducts and rate constants for their decomposition to apoprotein and their formation from apoprotein and cobalt(II) complex were measured at pH 5.5 and 25°C. Formation and dissociation rate constants for the adduct of cobalt carbonic anhydrase with pyridine-2,6-dicarboxylate could be measured from pH 5 to 7 and 10° to 25°C by stopped flow. Values of thermodynamic parameters for the various reactions agreed well with those estimated from the kinetic data. 相似文献
15.
16.
17.
18.
Denise C.O.F. Valdetaro Thomas C. Harrington Leonardo S.S. Oliveira Lúcio M.S. Guimarães Douglas L. McNew Lucas V.A. Pimenta Rivadalve C. Gonçalves Daniel A. Schurt Acelino C. Alfenas 《Fungal biology》2019,123(2):170-182
Ceratocystis fimbriata Ellis & Halsted recently was recorded causing seed and seedling blight on Carapa guianensis Aubl. (andiroba), a tree species native to the Amazon Rainforest and prized for its valuable timber and medicinal seed oil. C. fimbriata more commonly causes wilt type diseases in woody hosts, especially on non-native host trees. However, on andiroba the disease occurs on seedlings and seeds, affecting the species regeneration. We studied 73 isolates of C. fimbriata on andiroba from three regions of the Amazon Basin to see if they represented natural or introduced populations. Analysis of ITS rDNA sequences and phylogenetic analysis of mating type genes revealed new haplotypes of C. fimbriata from the Latin American Clade that were closely related to other Brazilian populations of the fungus. In mating experiments, andiroba isolates were inter-fertile with tester strains of C. fimbriata from Brazil and elsewhere, confirming that they belong to a single biological species. Using microsatellite markers, 14 genotypes and populations with intermediate levels of genetic variability were found, suggesting that the fungus is indigenous to the Amazon Basin. Inoculation tests indicated that the andiroba isolates are host-specialized on andiroba, supporting the proposition of the special form C. fimbriata f. sp. carapa. 相似文献
19.
20.