全文获取类型
收费全文 | 179篇 |
免费 | 11篇 |
专业分类
190篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2016年 | 5篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 10篇 |
2012年 | 7篇 |
2011年 | 11篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 7篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 2篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1958年 | 1篇 |
1957年 | 1篇 |
1955年 | 1篇 |
1954年 | 1篇 |
1943年 | 1篇 |
1937年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有190条查询结果,搜索用时 0 毫秒
71.
Seed size and seedling growth: differential response of Australian and British Fabaceae to nutrient limitation 总被引:1,自引:0,他引:1
Seed size is widely held to exert an important influence over plant establishment, but while large seeds are often assumed to be at an advantage in nutrient-limited conditions, there is in fact, little consistent evidence to support this hypothesis. Here, we examined the interspecific relationship between seedling growth and seed size for Australian and British Fabaceae species in nutrient solutions deficient in nitrogen, phosphorus, potassium or all nutrients combined (distilled water). The British species showed no consistent link between mean seed mass and seedling growth in nutrient-limited conditions. By contrast, all four nutrient-deficient treatments yielded a significant relationship for the Australian species. Linear regression showed that growth under balanced nutrient conditions was positively associated with growth without nutrients, although in fewer cases for the British species. We suggest that habitat-specific differences in regeneration conditions and/or evolutionary history may influence the role that seed size plays in dictating how seedlings of different species respond to nutrient shortage. We recommend caution in attempts to link traits like seed size to wider patterns of plant community ecology. 相似文献
72.
73.
A nuclear magnetic resonance (NMR) experiment is described for the direct detection of N-H[...]O=C hydrogen bonds (H-bonds) in 15N and 13C isotope-labeled biomolecules. This quantitative 'long-range' HNCO-COSY (correlation spectroscopy) experiment detects and quantifies electron-mediated scalar couplings across the H-bond (H-bond scalar couplings), which connect the magnetically active (15)N and (13)C nuclei on both sides of the H-bond. Detectable H-bonds comprise the canonical backbone H-bonds in proteins as well as other H-bonds in proteins and nucleic acids with N-H donors and O=C (carbonylic or carboxylic) acceptors. Unlike other NMR observables, which provide only indirect evidence of the presence of H-bonds, the H-bond scalar couplings identify all partners of the H-bond, the donor, the donor proton and the acceptor, in a single experiment. The size of the scalar couplings can be related to H-bond geometries. The time required to detect the N-H[...]O=C H-bonds in small proteins (< or = approximately 10 kDa) is typically on the order of 1 d at millimolar concentrations, whereas H-bond detection for larger proteins (< or = approximately 30 kDa) may be possible within several days depending on concentration, isotope composition, magnetic field strength and molecular weight. The proteins ubiquitin (8.6 kDa), dimeric RANTES (2 x 8.5 kDa) and MAP30 (30 kDa) are used as examples to illustrate this procedure. 相似文献
74.
Floriane Malvolti Olivier Cador Jean-François Halet Loic Toupet Stéphane Cordier 《Inorganica chimica acta》2011,374(1):288-301
The new thiocyanato- (5) and azido- (6) complexes were synthesized and studied under their Fe(II) and Fe(III) redox states. For the first time among the various [Fe(η5-C5Me5)(η2-dppe)]-based cationic radicals studied so far, the magnitude and spatial orientation of the g-tensor diagonal values were experimentally determined for 5[PF6]. These data are in good agreement with those issued from a DFT modelization. The changes experienced by the electronic structure of the Fe(II) complexes subsequent to oxidation are reminiscent of these previously observed for the known arylalkynyl analogues, albeit some differences can be pointed out. Thus, the differences observed in the 1H NMR spectra of 5[PF6] and 6[PF6] are attributed to a slower electronic spin relaxation and to the differently oriented magnetic anisotropy. The sizeable spin density evidenced by DFT on the terminal atom of the ligands of the Fe(III) complexes renders these new paramagnetic metallo-ligands quite appealing for accessing larger polynuclear molecular assemblies with magnetically interacting centers. 相似文献
75.
Richard Anaïs Orvain Francis Morelle Jérôme Romero-Ramirez Alicia Bernard Guillaume Paulin-Henricksson Stéphane Cordier Marie-Ange Montaudouin Xavier de Maire Olivier 《Ecosystems》2023,26(5):1077-1094
Ecosystems - Microphytobenthos (MPB) is one of the most important primary producers in coastal and estuarine ecosystems, where it plays a substantial role in many ecological functions. Although the... 相似文献
76.
J Bonnet M P Cordier E Ollagnon M H Guillaud D Raudrant J M Robert F Charvet 《Journal de génétique humaine》1987,35(4):279-289
The occurrence of a polymalformation pattern associated with a polydactyly indicates a mendelian inheritance. We report a case with renal hypoplasia, polydactyly, congenital heart defects. A large literature review makes the differential diagnosis and brings this case nearer to an anterior observation of the literature. We discuss an eventual new syndrome with autosomal recessive inheritance. 相似文献
77.
78.
Johnny Tam Guillaume Alan Cordier Joseph Steven Borbely ángel Sandoval álvarez Melike Lakadamyali 《PloS one》2014,9(7)
Multi-color stochastic optical reconstruction microscopy (STORM) is routinely performed; however, the various approaches for achieving multiple colors have important caveats. Color cross-talk, limited availability of spectrally distinct fluorophores with optimal brightness and duty cycle, incompatibility of imaging buffers for different fluorophores, and chromatic aberrations impact the spatial resolution and ultimately the number of colors that can be achieved. We overcome these complexities and develop a simple approach for multi-color STORM imaging using a single fluorophore and sequential labelling. In addition, we present a simple and versatile method to locate the same region of interest on different days and even on different microscopes. In combination, these approaches enable cross-talk-free multi-color imaging of sub-cellular structures. 相似文献
79.
Summary A new triple-resonance 3D HNCOCA pulse scheme is presented, designed to identify the backbone nuclei (HN, N, CO, C) of doubly labelled proteins. The two carbon frequencies are labelled along the same indirect dimension and the corresponding dwell times can be independently scaled in order to account for the relaxation properties and chemical shift ranges of the CO and C. If one takes advantage of the symmetry properties of the spectra in the course of the peak picking, this 3D scheme has the same sensitivity as the 4D experiment, but with an improved resolution. The sequence is illustrated on a 0.5 mM sample of Rhodobacter capsulatus cytochrome c a homodimeric paramagnetic protein of 2×14 kDa. A resonance assignment strategy, based on a low-concentration 13C/15N-labelled sample and a more concentrated 15N-labelled sample, is proposed for proteins where the expression system shows a limited efficiency. 相似文献
80.