全文获取类型
收费全文 | 1558篇 |
免费 | 53篇 |
国内免费 | 1篇 |
专业分类
1612篇 |
出版年
2022年 | 6篇 |
2021年 | 22篇 |
2020年 | 16篇 |
2019年 | 14篇 |
2018年 | 65篇 |
2017年 | 53篇 |
2016年 | 48篇 |
2015年 | 46篇 |
2014年 | 52篇 |
2013年 | 104篇 |
2012年 | 99篇 |
2011年 | 122篇 |
2010年 | 97篇 |
2009年 | 71篇 |
2008年 | 91篇 |
2007年 | 96篇 |
2006年 | 94篇 |
2005年 | 58篇 |
2004年 | 41篇 |
2003年 | 43篇 |
2002年 | 32篇 |
2001年 | 19篇 |
2000年 | 9篇 |
1999年 | 13篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 10篇 |
1995年 | 16篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 15篇 |
1991年 | 8篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1982年 | 10篇 |
1981年 | 7篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1967年 | 7篇 |
1961年 | 7篇 |
1958年 | 5篇 |
1957年 | 8篇 |
1956年 | 7篇 |
1928年 | 5篇 |
1927年 | 8篇 |
1917年 | 5篇 |
排序方式: 共有1612条查询结果,搜索用时 15 毫秒
31.
Ivana Macháková Jan Krekule Dagmar Souková Zdenk Pikryl Jaroslav Ullmann 《Journal of Plant Growth Regulation》1991,10(1):203-209
Aminoethoxyvinylglycine (AVG) applied as a droplet (3 l, 0.1 mM) to the plumule of seedlings of both the short-day plantChenopodium rubrum and the long-day plantChenopodium murale counteracted to a great extent or even canceled the inhibition of flowering due to exogenous indole-3-acetic acid (IAA). This effect was more pronounced with the two substances administered simultaneously than with later application of AVG alone. AVG by itself in some cases promoted the percentage of flowering in bothChenopodium species. Application of IAA to the shoot apex was shown to elevate ethylene production in both species, whereas application of AVG alone was shown to suppress it. Thus, ethylene may be considered an active agent of flowering inhibition brought about by IAA application. 相似文献
32.
Following the “Index of new names” (Theurillat etMoravec 1991a), the present work collects the names of syntaxa (in the sense of the Code of Phytosociological Nomenclature,Barkman et al. 1986) above subassociation rank typified in 1989. The list comprises 110 names of syntaxa. 相似文献
33.
Penicillium cyclopium growing in a surface culture with 2-ketoglutarate or glutamate as a sole carbon source produced ethylene in two phases. The first peak of ethylene production (EP 1) was associated with aerial mycelium growth whereas the second peak of ethylene production (EP 2) occurred with formation and maturation of conidia. Conidiation was induced by blue light between 120 and 172 h after the culture was started and depended on the presence of a carbon source at the stage of conidiophore initiation. Exogenous phosphate content dropper rapidly before the onset of conidiation. The EP 2 was connected with conidiation via this drop. Addition of phosphate prior to the conidiophore initiation and during conidiation inhibited EP 2 without affecting conidiation, but conidia lacked a green pigment and their germination ability decreased by 905. Exogenous ethylene did not restore normal development. The EP 2 in asporogenic cultures was evoked by incubation in the dark and by phosphate removal. The EP 2 and conidiation were accompanied by an increased oxygen consumption. The EP 1 yield of ethylene depended only on biomass growth and was unaffected by any treatment mentioned above. 相似文献
34.
Dagmar Jičínská Eduard Brabec Marcel Rejmánek Jan Jeník Joří Haager Josef Holub Věroslav Samek Hana Rambousková Josef Holub Marie Naděžda Končalová Robert Neuhäusl Josev Kyncl František Krahuleo Jaroslav Dobrý Blanka Úlehlová Jiří Úlehla Eliška Rybníčková Kamil Rybníček 《Folia Geobotanica》1982,17(4):431-448
35.
A mathematical model of the batch cultivation of Claviceps purpurea was formulated. The main attention was devoted to the effect of exocellular and intracellular phosphate on the growth of the mycelium and production of clavine alkaloid under experimental conditions without limitation by carbon and nitrogen sources. The method of nonlinear regression was used ot predict the optional technological regime of the phosphate addition in the batch culture at different time intervals of additions. 相似文献
36.
37.
George L. Wied Peter H. Bartels Marluce Bibbo May Chen Frank R. Reale Hans Schreiber Jaroslav J. Sychra 《Cell biochemistry and biophysics》1979,1(1):39-54
Cytologic preparations made from the tracheobronchial tree taken by the Schreiber catheter have been scanned by three color
microphotometry. The digitized cell images were processed by the analytical cytodiagnostic programs of the TICAS system. Cells
were sorted into two control groups and five groups of increasing atypia ranging from normal epithelium to invasive squamous
cell carcinoma. Standard statistical tests, including Wilk's Lambda, Rao's V, and the Kruskal-Wallis tests are performed on
these subsets of cell image features. This study demonstrates that discriminant analyses permit differentiation between normal
cells and those from marked atypia or carcinoma and that the classification achieves a high degree of agreement with visual
assignment. 相似文献
38.
Simultaneous and stepwise deprotection of the fully benzylated D-glucosyl esters of 1-benzyl N-benzyloxycarbonyl- and N-tert-butyloxycarbonyl-L-glutamic acid (1 and 5, respectively) have been examined. Catalytic hydrogenation of 1 led to intramolecular aminolysis to give pyroglutamic acid and D-glucose, but similar treatment in the presence of trifluoroacetic acid afforded both anomers of 1-O-(L-gamma-glutamyl)-D-glucopyranose, which were characterized as trifluoroacetates (2alpha and 2beta) and converted into 2,3,4,6-tetra-O-acetyl-1-O-[1-methyl N-(acetyl)-L-glutam-5-oyl]-D-glucopyranose (4) which was also prepared by a definitive method. Hydrogenolysis of 5 gave both anomers of 1-O-[N-(tert-butyloxycarbonyl)-L-gamma-glutamyl]-D-glucopyranose (6), which, upon treatment with trifluoroacetic acid at - 10 degrees, afforded 2alpha and 2beta, respectively. The structure of 6beta was established by its conversion into 2,3,4,6-tetra-O-acetyl-1-O-[1-methyl N-(tert-butyloxycarbonyl)-L-glutam-5-oyl]-beta-D-glucopyranose (7beta), whereas similar treatment of 6alpha gave a mixture of 1,3,4,6-tetra-O-acetyl-2-O-[1-methyl N-(tert-butyloxycarbonyl)-L-glutam-5-oyl]-alpha-D-glucopyranose (9) and 7alpha. A 1 leads to 2 acyl migration occurred during esterification of the aglycon carboxyl group of 6alpha with diazomethane to give 2-O-[1-methyl N-(tert-butyloxycarbonyl)-L-glutam-5-oyl]-alpha-D-glucopyranose (8). 相似文献
39.
Elevational species richness gradients in a hyperdiverse insect taxon: a global meta‐study on geometrid moths 下载免费PDF全文
Jan Beck Christy M. McCain Jan C. Axmacher Louise A. Ashton Florian Bärtschi Gunnar Brehm Sei‐Woong Choi Oldrich Cizek Robert K. Colwell Konrad Fiedler Cristina L. Francois Steven Highland Jeremy D. Holloway Jurie Intachat Tomas Kadlec Roger L. Kitching Sarah C. Maunsell Thomas Merckx Akihiro Nakamura Erica Odell Weiguo Sang Pagi S. Toko Jaroslav Zamecnik Yi Zou Vojtech Novotny 《Global Ecology and Biogeography》2017,26(4):412-424
40.