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71.
Field studies on a Daphnia galeata population in the mesotrophic man-made lake Saidenbach show that the fecundity of the animals depends on individual size, water temperature and the food supply (absolute quantity, specific food supply, food quality). These different factors are subsumed in the ingestion rate (rate of individual food intake per unit time), which is of an integrative character. The fecundity plotted versus ingestion rate yields a graph with the shape of a saturation curve. Attention is drawn to the consequences in terms of variation in population size. 相似文献
72.
73.
Vinuesa P Rojas-Jiménez K Contreras-Moreira B Mahna SK Prasad BN Moe H Selvaraju SB Thierfelder H Werner D 《Applied and environmental microbiology》2008,74(22):6987-6996
A highly supported maximum-likelihood species phylogeny for the genus Bradyrhizobium was inferred from a supermatrix obtained from the concatenation of partial atpD, recA, glnII, and rpoB sequences corresponding to 33 reference strains and 76 bradyrhizobia isolated from the nodules of Glycine max (soybean) trap plants inoculated with soil samples from Myanmar, India, Nepal, and Vietnam. The power of the multigene approach using multiple strains per species was evaluated in terms of overall tree resolution and phylogenetic congruence, representing a practical and portable option for bacterial molecular systematics. Potential pitfalls of the approach are highlighted. Seventy-five of the isolates could be classified as B. japonicum type Ia (USDA110/USDA122-like), B. liaoningense, B. yuanmingense, or B. elkanii, whereas one represented a novel Bradyrhizobium lineage. Most Nepalese B. japonicum Ia isolates belong to a highly epidemic clone closely related to strain USDA110. Significant phylogenetic evidence against the monophyly of the of B. japonicum I and Ia lineages was found. Analysis of their DNA polymorphisms revealed high population distances, significant genetic differentiation, and contrasting population genetic structures, suggesting that the strains in the Ia lineage are misclassified as B. japonicum. The DNA polymorphism patterns of all species conformed to the expectations of the neutral mutation and population equilibrium models and, excluding the B. japonicum Ia lineage, were consistent with intermediate recombination levels. All species displayed epidemic clones and had broad geographic and environmental distribution ranges, as revealed by mapping climate types and geographic origins of the isolates on the species tree. 相似文献
74.
Mutations in STRA6 cause a broad spectrum of malformations including anophthalmia, congenital heart defects, diaphragmatic hernia, alveolar capillary dysplasia, lung hypoplasia, and mental retardation 下载免费PDF全文
Pasutto F Sticht H Hammersen G Gillessen-Kaesbach G Fitzpatrick DR Nürnberg G Brasch F Schirmer-Zimmermann H Tolmie JL Chitayat D Houge G Fernández-Martínez L Keating S Mortier G Hennekam RC von der Wense A Slavotinek A Meinecke P Bitoun P Becker C Nürnberg P Reis A Rauch A 《American journal of human genetics》2007,80(3):550-560
75.
By comparing primary production (14C) and biomass variation it is possible to calculate the total losses of phytoplankton. For the mesotrophic drinking water reservoir Saidenbach, average loss rates of -0.31 d-1 for the total phytoplankton and -0.99 d-1 for nanoplankton were determined from September 1980 to May 1981. The greater the share of nanoplankton in the total phytoplankton, the less the real activity as reflected in biomass changes observed. The considerable (mainly nanoplankton) losses, however, cannot be explained by grazing or sedimentation. They are assumed to be caused by high mortality of flagellates due to a relatively high depth of mixing and their retention in the aphotic layer. 相似文献
76.
A routine method for the establishment of permanent growing lymphoblastoid cell lines 总被引:49,自引:8,他引:41
Heidemarie Neitzel 《Human genetics》1986,73(4):320-326
Summary Permanent lymphoblastoid cell lines are of great practical value in human clinical and experimental genetics. A detailed protocol for routine use is given for the establishment of lymphoblastoid lines from peripheral blood using Esptein-Barr virus and the immunosuppressivum Cyclosporin A. In addition, the biologic basis of this transformation system is briefly summarized. 相似文献
77.
Species effects on resource supply rates: do they influence competitive interactions? 总被引:4,自引:0,他引:4
Suding Katharine Nash Larson Julia R. Thorsos Eileen Steltzer Heidemarie Bowman William D. 《Plant Ecology》2004,175(1):47-58
We examined two ways in which species effects on nitrogen supply rates could influence species competitive interactions and
lead to coexistence between species with very different patterns of resource use. First, through differential effects on the
rates of resource cycling, species may modify resources in divergent directions to better tolerate neighbors under self-modified
conditions (tolerance modification). Second, plant-induced shifts in resource supply could enhance the degree to which species
can suppress individuals (suppression modification). We addressed these hypothesized mechanisms in the non-successional moist
meadow alpine tundra, which is codominated by Acomastylis rossii, a slow-growing roseaceous forb with high nutrient retention that is associated with slow rates of nitrogen supply, and Deschampsia caespitosa, a graminoid with rapid growth potential that is associated with fast rates of nitrogen (N) supply. Neighbors inhibited Acomastylis transplants (the species with high N retention) less than Deschampsia transplants (the species with rapid potential growth) in both neighborhood types, and hence neighborhood type did not influence
species tolerance to neighbors. Likewise, Acomastylis neighborhoods inhibited transplant growth more than Deschampsia neighborhoods regardless of transplant species identity. When N supply rates were enhanced through repeated N additions in
the two neighborhood types or in the presence of each species’ litter, the inhibitory effects associated with Acomastylis were offset to a greater degree than those associated with Deschampsia, as predicted by the suppression modification. These effects appeared to be density or size-dependent, with few effects observed
at low density. Our results suggest that species effects on supply rates may influence competitive interactions, particularly
if these effects are complemented by other sources of temporal or spatial variation such as pulses in resource availability.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
78.
Willeke P Schlüter B Becker H Schotte H Domschke W Gaubitz M 《Arthritis research & therapy》2007,9(6):R115
The aim of this study was to evaluate the efficacy and safety of mycophenolate sodium (MPS) in patients with primary Sjögren syndrome (pSS) refractory to other immunosuppressive agents. Eleven patients with pSS were treated with MPS up to 1,440 mg daily for an observation period of 6 months in this single-center, open-label pilot trial. At baseline, after 3 months, and after 6 months, we examined the clinical status, including glandular function tests, as well as different laboratory parameters associated with pSS. In addition, subjective parameters were determined on the basis of different questionnaires. Treatment with MPS was well tolerated in 8 of 11 patients. Due to vertigo or gastrointestinal discomfort, two patients did not complete the trial. One patient developed pneumonia 2 weeks after treatment and was withdrawn. In the remaining patients, MPS treatment resulted in subjective improvement of ocular dryness on a visual analogue scale and a reduced demand for artificial tear supplementations. However, no significant alterations of objective parameters for dryness of eyes and mouth were observed, although a substantial improvement of glandular functions occurred in two patients with short disease duration. In addition, treatment with MPS resulted in significant reduction of hypergammaglobulinemia and rheumatoid factors as well as an increase of complement levels and white blood cells. MPS promises to be an additional therapeutic option for patients with pSS, at least in those with shorter disease duration. Further investigations about the efficacy and safety of MPS in pSS have to be performed in larger numbers of patients. 相似文献
79.
Ioannis Gavvovidis Charlotte P?hlmann Juan Alberto Marchal Markus Stumm Daisuke Yamashita Tatsuya Hirano Detlev Schindler Heidemarie Neitzel Marc Trimborn 《Cell cycle (Georgetown, Tex.)》2010,9(24):4893-4899
Mutations in the MCPH1 gene cause primary microcephaly associated with a unique cellular phenotype of misregulated chromosome condensation. The encoded protein contains three BRCT domains, and accumulating data show that MCPH1 is involved in the DNA damage response. However, most of this evidence has been generated by experiments using RNA interference (RNAi) and cells from non-human model organisms. Here, we demonstrate that patient-derived cell lines display a proficient G2/M checkpoint following ionizing irradiation (IR) despite homozygous truncating mutations in MCPH1. Moreover, chromosomal breakage rates and the relocation to DNA repair foci of several proteins functioning putatively in an MCPH1-dependent manner are normal in these cells. However, the MCPH1-deficient cells exhibit a slight delay in re-entering mitosis and delayed resolution of γH2AX foci following IR. Analysis of chromosome condensation behavior following IR suggests that these latter observations may be related to hypercondensation of the chromatin in cells with MCPH1 mutations. Our results indicate that the DNA damage response in human cells with truncating MCPH1 mutations differs significantly from the damage responses in cells of certain model organisms and in cells depleted of MCPH1 by RNAi. These subtle effects of human MCPH1 deficiency on the cellular DNA damage response may explain the absence of cancer predisposition in patients with biallelic MCPH1 mutations.Key words: chromosome condensation, DNA damage, G2/M checkpoint, ionizing radiation, PCC syndrome, primary microcephaly, repair foci 相似文献
80.
For the first time in Acanthaceae a comparative study of orbicules forming stable, coherent orbicular walls and the respective pollen ornamentation was undertaken. A peculiar acetolysis resistant, often species specific orbicular wall is typical for many genera. In some cases the orbicular wall ornamentation resembles closely the pollen ornamentation, in others it differs to a variable degree. The presumed function of orbicular walls is discussed. 相似文献