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821.
The addition of combined nitrogen to substrate at an appropriate rate can stimulate N2-fixation thus inreasing the efficiency of the Alnus-Frankia symbiosis. To examine how nitrogen additions can effect the peformance of different pairs of symbionts, growth and time course
of N2-fixation were studied in plants supplied with NH4NO3. Two cloned ofAlnus glutinosa (L.) Gaertn., propagatedin vitro, were inoculated with two strains ofFrankia (AVP3d and ACN14a) and grown in a greenhouse. Calcined montmorillonite (TotfaiceR) was used as growth substrate. Six N treatments were made up of varied amounts of NH4NO3 supplied in one single addition shortly before inoculation. Weekly measurements of shoot height and repeated measurements
of nitrogenase activity (acetylene reduction) performed on intact root systems were used to monitor the development of the
symbioses.
Nitrogen treatments containing from 0.10 to 0.68 mg N g−1 dry substrate stimulated N2-fixation as well as growth. The relative performance of the two clones was different according to N treatment; one clone
showed a greater benefit from the nitrogen input. Our results support the recommendation that selection of symbionts according
to performance should be carried out with an input of combined nitrogen. This can provide optimum conditions for the development
of each pair of symbionts. 相似文献
822.
R. Brdika 《Animal genetics》1984,15(2):79-83
By comparing electrophoretic patterns of urinary proteins from males of different inbred strains and pertinent hybrids, a new polymorphic locus designated Mur-2 has been detected. 相似文献
823.
We study the dynamics of sexually transmitted pathogens in a heterosexually active population, where females are divided
into two different groups based on their susceptibility to two distinct pathogenic strains. It is assumed that a host cannot
be invaded simultaneously by both disease agents and that when symptoms appear – a function of the pathogen, strain, virulence,
and an individual’s degree of susceptibility – then individuals are treated and/or recover. Heterogeneity in susceptibility
to the acquisition of infection and/or in variability in the length of the infection period of the female subpopulations is
incorporated. Pathogens’ coexistence is highly unlikely on homogeneously mixing female and male populations with no heterogeneity
among individuals of either gender. Variability in susceptibility in the female subpopulation makes coexistence possible albeit
under a complex set of circumstances that must include differences in contact/mixing rates between the groups of females and
the male population as well as differences in the lengths of their average periods of infectiousness for the three groups.
Received 25 July 1995; received in revised form 6 May 1996 相似文献
824.
R. Robert C. Mahaza A. Marot-Leblond G. Tronchin J.M. Senet 《FEMS microbiology letters》1991,78(2-3):301-304
Binding of fibrinogen to various Candida albicans strains has been investigated by immunofluorescence microscopy on kidney sections of experimentally infected mice. Fibrinogen appeared to bind to both mycelium and blastospores in situ whereas previous studies, carried out in vitro, have shown fibrinogen binding to mycelial elements only. 相似文献
825.
Specificity of Agrobacterium-mediated delivery of maize streak virus DNA to members of the Gramineae 总被引:3,自引:0,他引:3
Margaret I. Boulton Wallace G. Buchholz Melanie S. Marks Peter G. Markham Jeffrey W. Davies 《Plant molecular biology》1989,12(1):31-40
Parameters affecting the efficiency of agroinfection of maize streak virus (MSV) in maize have been determined. Monomeric units, cloned at a number of sites in the MSV genome were not infectious but multimeric units containing partial duplications were equally as infectious as complete tandem dimeric clones. Inoculation of tandem dimeric units conjugated into different strains of Agrobacterium showed that both A. tumefaciens and A. rhizogenes were able to transfer DNA to maize and this ability was Ti (or Ri) plasmid-specific. Nopaline strains of A. tumefaciens and both agropine and mannopine A. rhizogenes strains efficiently transferred MSV DNA to maize. A number of strains were capable of MSV DNA transfer to other members of the Gramineae, providing information which may be essential for Agrobacterium-mediated transformation of monocotyledonous plants. 相似文献
826.
827.
A total of fourteen Artemia samples from Colombia, Venezuela, Curaçao (Netherlands Antilles), Puerto Rico, and reference samples from U.S.A. (San Francisco Bay, SFB) belonging to the superspecies Artemia franciscana, and Argentina (A. persimilis), were analysed with the RAPD technique in order to demonstrate genetic dissimilarities. Pearson's correlation coefficients between the DNA banding patterns were calculated. They served as input values for the construction of UPGMA dendrograms. The results indicate that, within the collection of Colombian, Venezuelan and the two Netherlands Antilles Artemiacyst samples examined, two different groups seem to exist. Geographically, the mountainous area of Sierra Nevada de Santa Marta separates these two groups (lower Caribbean to the South and middle Caribbean to the North). Although the Caribbean, North and South American populations belong to A. franciscana, genetic discontinuities are to be expected due to habitat differences and geographic isolation. The Sierra Nevada (with an altitude of about 5800 m) emerges as the barrier very likely to explain the observed RAPD differences. Little genetic variability was present in the Colombian samples from Manaure that were collected almost every ten years, nor in the samples from Galerazamba collected almost two decades apart, although these samples were more likely subjected to different prevailing environmental conditions. The SFB population did not show a very close relation with all Caribbean populations analyzed, including the Puerto Rican. All A. franciscana populations analyzed were divergent from A. persimilis(Argentina). 相似文献
828.
829.
K. Szklarczyk M. Korostynski S. Golda W. Solecki R. Przewlocki 《Genes, Brain & Behavior》2012,11(8):977-985
Post‐traumatic stress disorder (PTSD) is an anxiety disorder that develops in predisposed individuals following a terrifying event. Studies on isogenic animal populations might explain susceptibility to PTSD by revealing associations between the molecular and behavioural consequences of traumatic stress. Our study employed four inbred mouse strains to search for differences in post‐stress response to a 1.5‐mA electric foot shock. One day to 6 weeks after the foot shock anxiety, depression and addiction‐like phenotypes were assessed. In addition, expression levels of selected stress‐related genes were analysed in hippocampus and amygdala. C57BL/6J mice exhibited up‐regulation in the expression of Tsc22d3, Nfkbia, Plat and Crhr1 genes in both brain regions. These alterations were associated with an increase of sensitized fear and depressive‐like behaviour over time. Traumatic stress induced expression of Tsc22d3, Nfkbia, Plat and Fkbp5 genes and developed social withdrawal in DBA/2J mice. In 129P3/J strain, exposure to stress produced the up‐regulation of Tsc22d3 and Nfkbia genes and enhanced sensitivity to the rewarding properties of morphine. Whereas, SWR/J mice displayed increase only in Pdyn expression in the amygdala and had the lowest conditioned fear. Our results reveal a complex genetic background of phenotypic variation in response to stress and indicate the SWR/J strain as a valuable model of stress resistance. We found potential links between the alterations in expression of Tsc22d3, Nfkbia and Pdyn, and different aspects of susceptibility to stress. 相似文献
830.
Gang Guo Lei Zhang Zhou Zhou Qiqi Ma Jianping Liu Chenguang Zhu Lei Zhu Ziniu Yu & Ming Sun 《FEMS microbiology letters》2008,282(1):1-7
Bacillus thuringiensis produces various groups of active proteins, such as Cyt, Vip and Parasporin, in addition to the Cry protein. In this study we show S-layer proteins to be a new group of parasporal inclusions of B. thuringiensis . The S-layer consists of a two-dimensional lattice structure and is the outermost component of many archaeobacteria and eubacteria. The parasporal inclusion of B. thuringiensis strain CTC was found to be not a typical crystal protein encoded by the cry gene, but a proteinaceous inclusion encoded by the S-layer gene. Furthermore, the CTC-like strains (with their parasporal inclusions coded by the S-layer gene) are widely distributed and accounted for 25.4% of the B. thuringiensis strains tested. These strains constitue a new group of parasporal inclusions encoded by the S-layer gene of B. thuringiensis and shed new light on B. thuringiensis nontoxic strains. 相似文献