全文获取类型
收费全文 | 256篇 |
免费 | 38篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 1篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 9篇 |
2013年 | 9篇 |
2012年 | 18篇 |
2011年 | 17篇 |
2010年 | 15篇 |
2009年 | 9篇 |
2008年 | 18篇 |
2007年 | 16篇 |
2006年 | 19篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 8篇 |
2002年 | 14篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 10篇 |
1998年 | 8篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1966年 | 3篇 |
1965年 | 1篇 |
排序方式: 共有294条查询结果,搜索用时 31 毫秒
61.
Richard Bischof Espen R. Gregersen Henrik Brøseth Hans Ellegren Øystein Flagstad 《Ecology and evolution》2016,6(5):1527-1536
Due to its conspicuous manifestations and its capacity to shape the configuration and dynamics of wild populations, territorial behavior has long intrigued ecologists. Territoriality and other animal interactions in situ have traditionally been studied via direct observations and telemetry. Here, we explore whether noninvasive genetic sampling, which is increasingly supplementing traditional field methods in ecological research, can reveal territorial behavior in an elusive carnivore, the wolverine (Gulo gulo). Using the locations of genotyped wolverine scat samples collected annually over a period of 12 years in central Norway, we test three predictions: (1) male home ranges constructed from noninvasive genetic sampling data are larger than those of females, (2) individuals avoid areas used by other conspecifics of the same sex (intrasexual territoriality), and (3) avoidance of same‐sex territories diminishes or disappears after the territory owner's death. Each of these predictions is substantiated by our results: sex‐specific differences in home range size and intrasexual territoriality in wolverine are patently reflected in the spatial and temporal configuration of noninvasively collected genetic samples. Our study confirms that wildlife monitoring programs can utilize the spatial information in noninvasive genetic sampling data to detect and quantify home ranges and social organization. 相似文献
62.
The concentration of twelve elements—potassium, calcium, manganese, iron, cobalt, nickel, copper, zinc, arsenic, selenium,
bromine, and rubidium—in anterior pituitaries from human subjects and rats was measured using Particle Induced X-ray Emission
(PIXE). The human material included anterior pituitaries from 37 normal human subjects, 27 males and 10 females, all of whom
died from traumatic lesions. Excluded from the investigations were persons with alcohol abuse, regular use of drugs, and babies
younger than 1 year.
For selenium, zinc, bromine, and to some extent copper, there was good correlation between the amounts found in anterior pituitaries
from rats and human subjects. A significant difference between male and female rat pituitaries was observed for copper, iron,
and rubidium, whereas for humans significant difference was only observed for manganese. Anterior pituitaries from human females
contained generally more zinc than male glands, but the concentration of zinc in young males was higher than in females. The
present study also indicates age related differences in the copper content in anterior pituitaries from human subjects, since
pituitaries from humans between 15–45 years contained 25% more copper than those from younger or older persons. The opposite
pattern was observed in males. For such elements as Cu, Fe, Mn, and Se, the content in the anterior pituitary from human subjects
was 1.6–2 times that stated for other endocrine organs. 相似文献
63.
Lars S. Nielsen Alexandra Baer Christian Müller Kristian Gregersen Nina T. Mønster Søren K. Rasmussen Dietmar Weilguny Anne B. Tolstrup 《Molecular biotechnology》2010,45(3):257-266
We have previously described the development and implementation of a strategy for production of recombinant polyclonal antibodies
(rpAb) in single batches employing CHO cells generated by site-specific integration, the SympressTM I technology. The SympressTM I technology is implemented at industrial scale, supporting a phase II clinical development program. Production of recombinant
proteins by site-specific integration, which is based on incorporation of a single copy of the gene of interest, makes the
SympressTM I technology best suited to support niche indications. To improve titers while maintaining a cost-efficient, highly reproducible
single-batch manufacturing mode, we have evaluated a number of different approaches. The most successful results were obtained
using random integration in a new producer cell termed ECHO, a CHO DG44 cell derivative engineered for improved productivity
at Symphogen. This new expression process is termed the SympressTM II technology. Here we describe proof-of-principle data demonstrating the feasibility of the SympressTM II technology for single-batch rpAb manufacturing using two model systems each composed of six target-specific antibodies.
The compositional stability and the batch-to-batch reproducibility of rpAb produced by the ECHO cells were at least as good
as observed previously using site-specific integration technology. Furthermore, the new process had a significant titer increase. 相似文献
64.
65.
Michael F Seldin Omar K Alkhairy Annette T Lee Janine A Lamb Jon Sussman Ritva Pirskanen-Matell Fredrik Piehl Jan J G M Verschuuren Anna Kostera-Pruszczyk Piotr Szczudlik David McKee Angelina H Maniaol Hanne F Harbo Benedicte A Lie Arthur Melms Henri-Jean Garchon Nicholas Willcox Peter K Gregersen Lennart Hammarstrom 《Molecular medicine (Cambridge, Mass.)》2015,21(1):769-781
To investigate the genetics of late-onset myasthenia gravis (LOMG), we conducted a genome-wide association study imputation of >6 million single nucleotide polymorphisms (SNPs) in 532 LOMG cases (anti–acetylcholine receptor [AChR] antibody positive; onset age ≥50 years) and 2,128 controls matched for sex and population substructure. The data confirm reported TNFRSF11A associations (rs4574025, P = 3.9 × 10−7, odds ratio [OR] 1.42) and identify a novel candidate gene, ZBTB10, achieving genome-wide significance (rs6998967, P = 8.9 × 10−10, OR 0.53). Several other SNPs showed suggestive significance including rs2476601 (P = 6.5 × 10−6, OR 1.62) encoding the PTPN22 R620W variant noted in early-onset myasthenia gravis (EOMG) and other autoimmune diseases. In contrast, EOMG-associated SNPs in TNIP1 showed no association in LOMG, nor did other loci suggested for EOMG. Many SNPs within the major histocompatibility complex (MHC) region showed strong associations in LOMG, but with smaller effect sizes than in EOMG (highest OR ~2 versus ~6 in EOMG). Moreover, the strongest associations were in opposite directions from EOMG, including an OR of 0.54 for DQA1*05:01 in LOMG (P = 5.9 × 10−12) versus 2.82 in EOMG (P = 3.86 × 10−45). Association and conditioning studies for the MHC region showed three distinct and largely independent association peaks for LOMG corresponding to (a) MHC class II (highest attenuation when conditioning on DQA1), (b) HLA-A and (c) MHC class III SNPs. Conditioning studies of human leukocyte antigen (HLA) amino acid residues also suggest potential functional correlates. Together, these findings emphasize the value of subgrouping myasthenia gravis patients for clinical and basic investigations and imply distinct predisposing mechanisms in LOMG. 相似文献
66.
Yang J Zhao J Jiang W Nakaguchi T Kunwald P Grundy D Gregersen H 《American journal of physiology. Gastrointestinal and liver physiology》2012,302(9):G1025-G1034
This study aimed to characterize the effect of mechanical stimuli on mesenteric afferent nerve signaling in the isolated rat jejunum in vitro. This was done to determine the effect of mechanical stresses and strains relative to nonmechanical parameters (neurogenic adaptation). Mechanical stimulations were applied to a segment of jejunum from 15 rats using ramp distension with water at three rates of distension, a relaxation test (volume maintained constant from initial pressure of 20 or 40 mmHg), and a creep test (pressure maintained constant). Circumferential stress and strain and the spike rate increase ratio were calculated for evaluation of afferent nerve activity during the mechanical stimulations. Ramp distension evoked two distinct phases of afferent nerve signaling as a function of circumferential stress or strain. Changing the volume distension rate did not change the stress-strain relationship, but faster distension rate increased the afferent firing rate (P < 0.05). In the stress relaxation test, the spike rate declined faster and to a greater extent than the stress. In the creep test, the spike rate declined, despite a small increase in the strain. Three classes of mechanosensitive single-afferent units (low, wide dynamic range, and high threshold units) showed different response profiles against stress and strain. Low-threshold units exhibited a near linear relationship against the strain (R(2) = 0.8095), whereas high-threshold units exhibited a linear profile against the stress (R(2) = 0.9642). The afferent response is sensitive to the distension speed and to the stress and strain level during distension. However, the afferent nerve response is not a simple function of either stress or strain. Nonmechanical time-dependent adaptive responses other than those related to viscoelasticity also play a role. 相似文献
67.
Primary and secondary kinetic and equilibrium isotope effects are calculated with density-functional methods for the in-line dianionic methanolysis of the native (unsubstituted) and thio-substituted cyclic phosphates. These reactions represent reverse reaction models for RNA transesterification under alkaline conditions. The effect of solvent is treated with explicit (single and double) water molecules and self-consistently with an implicit (continuum) solvation model. Singly substituted reactions at the nonbridging O(P1) position and bridging O(2)('), O(3)('), and O(5)(') positions and a doubly substituted reaction at the O(P1) and O(P2) positions were considered. Aqueous free energy barriers are calculated, and the structures and bond orders of the rate-controlling transition states are characterized. The results are consistent with available experimental data and provide useful information for the interpretation of measured isotope and thio effects used to probe mechanism in phosphoryl transfer reactions catalyzed by enzymes and ribozymes. 相似文献
68.
Cino Pertoldi Małgorzata Tokarska Jan M. Wójcik Agata Kawałko Ettore Randi Torsten N. Kristensen Volker Loeschcke David Coltman Gregory A. Wilson Vivi R. Gregersen Christian Bendixen 《Acta theriologica》2010,55(2):97-108
Here we present the first attempt to use the BovineSNP50 Illumina Genotyping BeadChip for genome-wide screening of European bison Bison bonasus bonasus (EB), two subspecies of American bison: the plains bison Bison bison bison (PB), the wood bison Bison bison athabascae (WB) and seven cattle Bos taurus breeds. Our aims were to (1) reconstruct their evolutionary relationships, (2) detect any genetic signature of past bottlenecks and to quantify the consequences of bottlenecks on the genetic distances amongst bison subspecies and cattle, and (3) detect loci under positive or stabilizing selection. A Bayesian clustering procedure (STRUCTURE) detected ten genetically distinct clusters, with separation among all seven cattle breeds and European and American bison, but no separation between plain and wood bison. A linkage disequilibrium based program (LDNE) was used to estimate the effective population size (N e) for the cattle breeds; N e was generally low, relative to the census size of the breeds (cattle breeds: mean N e = 299.5, min N e = 18.1, max N e = 755.0). BOTTLENECK 1.2 detected signs of population bottlenecks in EB, PB and WB populations (sign test and standardized sign test: p = 0.0001). Evidence for loci under selection was found in cattle but not in bison. All extant wild populations of bison have shown to have survived severe bottlenecks, which has likely had large effects on genetic diversity within and differentiation among groups. 相似文献
69.
Characterization of Pasteurellaceae‐like bacteria isolated from clinically affected psittacine birds
R.H. Gregersen C. Neubauer H. Christensen B. Korczak A.M. Bojesen M. Hess M. Bisgaard 《Journal of applied microbiology》2010,108(4):1235-1243
Aims: The aim of the present investigation was to identify and characterize Pasteurella‐like isolates obtained from clinically affected psittacine birds. Methods and Results: A total of 37 isolates from psittacine birds tentatively classified with the family Pasteurellaceae were characterized phenotypically. The genetic relationship was investigated by sequencing of partial rpoB and 16S rRNA genes for selected isolates. The results obtained were compared with the data from 16 reference strains. Nine isolates were identified as Gallibacterium spp., 16 as Volucribacter spp. or Volucribacter‐like, while 11 isolates were classified as taxon 44 of Bisgaard. A single isolate was identified as Pasteurella multocida. Conclusions: Characterization of Pasteurellaceae by traditional methods is often inconclusive because of inconsistent reactions and phenotypic diversity. For the same reason, genotyping is essential to allow proper classification as demonstrated in the present study. Significance and Impact of the Study: Limited information exists on the isolation and significance of Pasteurellaceae associated with clinically affected psittacine birds showing signs of digestive and/or respiratory disorders. The present investigations demonstrated that these organisms are widely distributed among clinically affected birds, but isolation of these taxa cannot be unambiguously correlated with the symptoms observed. 相似文献
70.
Data on morphological and biomechanical remodelling are needed to understand the mechanisms behind intestinal obstruction. The effect of partial obstruction on mechanical properties with reference to the zero-stress state and on the histomorphological properties of the guinea pig small intestine was determined in this study. Partial obstruction and sham operation were surgically created in mid-jejunum of guinea pigs. The animals survived 2, 4, 7, and 14 days. The age-matched guinea pigs that were not operated served as normal controls. The segment proximal to the obstruction site was used for histological analysis, no-load state and zero-stress state data, and distension test. The segment for distension was immersed in an organ bath and inflated to 10 cm H2O. The outer diameter change during the inflation was monitored using a microscope with CCD camera. Circumferential stresses and strains were computed from the diameter, pressure and the zero-stress state data. The opening angle and absolute value of residual strain decreased (P<0.01 and P<0.001) whereas the wall thickness, wall cross-sectional area, and the wall stiffness increased after 7 days obstruction (P<0.05, P<0.01). Histologically, the muscle and submucosa layers, especially the circumferential muscle layer increased in thickness after obstruction. The opening angle and residual strain mainly depended on the thickness of the muscle layer whereas the wall stiffness mainly depended on the thickness of the submucosa layer. In conclusion, the histomorphological and biomechanical properties of small intestine (referenced for the first time to the zero-stress state) remodel proximal to the obstruction site in a time-dependent manner. 相似文献