全文获取类型
收费全文 | 423篇 |
免费 | 24篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 8篇 |
2018年 | 10篇 |
2017年 | 5篇 |
2016年 | 13篇 |
2015年 | 21篇 |
2014年 | 20篇 |
2013年 | 37篇 |
2012年 | 27篇 |
2011年 | 32篇 |
2010年 | 16篇 |
2009年 | 18篇 |
2008年 | 22篇 |
2007年 | 25篇 |
2006年 | 24篇 |
2005年 | 25篇 |
2004年 | 12篇 |
2003年 | 18篇 |
2002年 | 23篇 |
2001年 | 3篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1990年 | 7篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1957年 | 1篇 |
1939年 | 1篇 |
1930年 | 1篇 |
排序方式: 共有447条查询结果,搜索用时 15 毫秒
81.
82.
83.
Spirodela oligorrhiza (duckweed) is capable of transforming some steroids of the androstane series. Hydrolysis of the acetates of testosterone and of 3β-hydroxyandrost-5-en-17-one by this species yielded the corresponding alcohols. Further transformation of testosterone and reduction of androst-4-ene-3,17-dione indicated the interconversions of the hydroxyl-ketone function on C-17 and reduction of the Δ4-double bond to the trans-A/B system. Only a trace amount of 3β-hydroxyandrost-5-en-17-one underwent further transformations. 相似文献
84.
Jerzy Paszkowski Alex Peterhans Roland Bilang Witold Filipowicz 《Plant molecular biology》1992,19(5):825-836
A plant selectable marker gene consisting of cauliflower mosaic virus expression signals and the proteincoding sequence of bacterial neomycin phosphotransferase was modified by insertion of an intron sequence from a storage protein gene, phaseolin. Correct and efficient splicing of the resulting mosaic RNA was observed in transgenic tobacco plants. The insertion of various linkers or gradual increase of intron size by addition in both orientations of internal intron sequences from another plant gene (parsley, 4-coumarate ligase) had little or no effect on the precision of slicing. The gene activity measured by selectability assay in the protoplast transformation showed that only introns enlarged to 1161 bases and longer caused decreased selectability. The suitability of such mosaic marker genes for studies of RNA splicing, DNA recombination and early events after infection of plants with Agrobacterium is discussed. 相似文献
85.
86.
Witold Wachowiak Julia Zaborowska Bartosz Łabiszak Annika Perry Giovanni M. Zucca Santiago C. González-Martínez Stephen Cavers 《Tree Genetics & Genomes》2018,14(6):83
Efforts to detect loci under selection in plants have mostly focussed on single species. However, assuming that intraspecific divergence may lead to speciation, comparisons of genetic variation within and among recently diverged taxa can help to locate such genes. In this study, coalescent and outlier detection methods were used to assess nucleotide polymorphism and divergence at 79 nuclear gene fragments (1212 SNPs) in 16 populations (153 individuals) of the closely related, but phenotypically and ecologically distinct, pine taxa Pinus mugo, P. uliginosa and P. uncinata across their European distributions. Simultaneously, mitochondrial DNA markers, which are maternally inherited in pines and distributed by seeds at short geographic distance, were used to assess genetic relationships of the focal populations and taxa. The majority of nuclear loci showed homogenous patterns of variation between the taxa due to a high number of shared SNPs and haplotypes, similar levels of polymorphism, and low net divergence. However, against this common genetic background and an overall low population structure within taxa at mitochondrial markers, we identified several genes showing signatures of selection, accompanied by significant intra- and interspecific divergence. Our results indicate that loci involved in species divergence may be involved in intraspecific local adaptation. 相似文献
87.
Bkaily Ghassan Pothier Pierre D'Orléans-Juste Pedro Simaan May Jacques Danielle Jaalouk Doris Belzile François Hassan Ghada Boutin Chantal Haddad Georges Neugebauer Witold 《Molecular and cellular biochemistry》1997,172(1-2):171-194
In recent years, fluorescence microscopy imaging has become an important tool for studying cell structure and function. This non invasive technique permits characterization, localisation and qualitative quantification of free ions, messengers, pH, voltage and a pleiad of other molecules constituting living cells. In this paper, we present results using various commercially available fluorescent probes as well as some developed in our laboratory and discuss the advantages and limitations of these probes in confocal microscopy studies of the cardiovascular system. 相似文献
88.
Dehalogenation Activity of Selected Fungi Toward δ‐Iodo‐γ‐Lactone Derived from trans,trans‐Farnesol
下载免费PDF全文
![点击此处可从《化学与生物多样性》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Anna Gliszczyńska Witold Gładkowski Marta Świtalska Joanna Wietrzyk Antoni Szumny Elżbieta Gębarowska Czesław Wawrzeńczyk 《化学与生物多样性》2016,13(4):477-482
Time‐course of biotransformation of racemic trans‐4‐((E)‐4′,8′‐dimethylnona‐3′,7′‐dien‐1‐yl)‐5‐iodomethyl‐4‐methyldihydrofuran‐2‐one ( 1 ) in fungal and yeast cultures was investigated. In these conditions, the substrate 1 was enantioselectively dehalogenated yielding 4‐((E)‐4′,8′‐dimethylnona‐3′,7′‐dien‐1‐yl)‐4‐methyl‐5‐methylenedihydrofuran‐2‐one ( 2 ) and its structure was established based on the spectroscopic data. The most effective biocatalyst used was Didymosphaeria igniaria, which catalyzed the process with highest rate and enantioselectivity (ee of product = 76%). The antiproliferative activity of δ‐iodo‐γ‐lactone 1 , product of its biotransformation 2 , and starting substrate (farnesol) were evaluated toward two cancer cell lines: A549 (human lung adenocarcinoma) and HL‐60 (human promyelocytic leukemia). 相似文献
89.
The majority of abnormal sex chromosome complexes in the male have been considered to be variants of Klinefelter''s syndrome but an exception should probably be made in the case of the XXXXY individual who has distinctive phenotypic features. Clinical, radiological and cytological data on three new cases of XXXXY syndrome are presented and 30 cases from the literature are reviewed. In many cases the published clinical and radiological data were supplemented and re-evaluated. Mental retardation, usually severe, was present in all cases. Typical facies was observed in many; clinodactyly of the fifth finger was seen in nearly all.Radiological examination revealed abnormalities in the elbows and wrists in all the 19 personally evaluated cases, and other skeletal anomalies were very frequent. Cryptorchism is very common and absence of Leydig''s cells may differentiate the XXXXY chromosome anomaly from polysomic variants of Klinefelter''s syndrome. The relationship of this syndrome to Klinefelter''s syndrome and to Down''s syndrome is discussed. 相似文献
90.
Résumé Les auteurs discutent les résultats de l'expérimentation de la méthode complexe à la liquidation du foyer primaire de gradation
deAcantholyda nemoralis
Thoms.
Ce complexe comprenait les expériences suivantes: concentration de Sangliers, concentration d'Oiseaux, colonisation artificielle
de Fourmis, application deTrichogramma embryophagum
Htg., introduction deNeoaplectana janickii
Weis. etKoeh. ainsi que les anneaux toxiques. Les résultats obtenus sont satisfaisants.
相似文献