全文获取类型
收费全文 | 538篇 |
免费 | 75篇 |
出版年
2021年 | 14篇 |
2020年 | 17篇 |
2019年 | 13篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 16篇 |
2015年 | 14篇 |
2014年 | 24篇 |
2013年 | 19篇 |
2012年 | 22篇 |
2011年 | 25篇 |
2010年 | 28篇 |
2009年 | 24篇 |
2008年 | 21篇 |
2007年 | 20篇 |
2006年 | 19篇 |
2005年 | 20篇 |
2004年 | 18篇 |
2003年 | 16篇 |
2002年 | 14篇 |
2001年 | 12篇 |
2000年 | 14篇 |
1999年 | 15篇 |
1998年 | 7篇 |
1997年 | 10篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 5篇 |
1991年 | 11篇 |
1990年 | 13篇 |
1989年 | 5篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1983年 | 6篇 |
1981年 | 10篇 |
1979年 | 7篇 |
1978年 | 11篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1973年 | 7篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1970年 | 3篇 |
1968年 | 3篇 |
1967年 | 3篇 |
1908年 | 4篇 |
排序方式: 共有613条查询结果,搜索用时 343 毫秒
101.
Disomic Thinopyrum intermedium addition lines in wheat with barley yellow dwarf virus resistance and with rust resistances. 总被引:14,自引:0,他引:14
P J Larkin P M Banks E S Lagudah R Appels C Xiao X Zhiyong H W Ohm R A McIntosh 《Génome》1995,38(2):385-394
Zhong 5 is a partial amphiploid (2n = 56) between Triticum aestivum (2n = 42) and Thinopyrum intermedium (2n = 42) carrying all the chromosomes of wheat and seven pairs of chromosomes from Th. intermedium. Following further backcrossing to wheat, six independent stable 2n = 44 lines were obtained representing 4 disomic chromosome addition lines. One chromosome confers barley yellow dwarf virus (BYDV) resistance, whereas two other chromosomes carry leaf and stem rust resistance; one of the latter also confers stripe rust resistance. Using RFLP and isozyme markers we have shown that the extra chromosome in the Zhong 5-derived BYDV resistant disomic addition lines (Z1, Z2, or Z6) belongs to the homoeologous group 2. It therefore carries a different locus to the BYDV resistant group 7 addition, L1, described previously. The leaf, stem, and stripe rust resistant line (Z4) carries an added group 7 chromosome. The line Z3 has neither BYDV nor rust resistance, is not a group 2 or group 7 addition, and is probably a group 1 addition. The line Z5 is leaf and stem rust resistant, is not stripe rust resistant, and its homoeology remains unknown. 相似文献
102.
The aspiration biopsy cytologic features of a malignant schwannoma metastatic to the lung in a 39-year-old black female with von Recklinghausen's disease are reported. Cytologic features of malignant sarcomas having a spindle-cell pattern are described along with a discussion of the cytologic differential diagnosis. This is believed to be the first reported case of a malignant schwannoma involving the lung diagnosed by aspiration cytology and demonstrates the usefulness of the technique in evaluating patients with metastatic sarcomas. 相似文献
103.
The nucleotide sequence of a 4.39-kb DNA fragment encoding the alpha-glucosidase gene of Candida tsukubaensis is reported. The cloned gene contains a major open reading frame (ORF 1) which encodes the alpha-glucosidase as a single precursor polypeptide of 1070 amino acids with a predicted molecular mass of 119 kDa. N-terminal amino acid sequence analysis of the individual subunits of the purified enzyme, expressed in the recombinant host Saccharomyces cerevisiae, confirmed that the alpha-glucosidase precursor is proteolytically processed by removal of an N-terminal signal peptide to yield the two peptide subunits 1 and 2, of molecular masses 63-65 kDa and 50-52 kDa, respectively. Both subunits are secreted by the heterologous host S. cerevisiae in a glycosylated form. Coincident with its efficient expression in the heterologous host, the C. tsukubaensis alpha-glucosidase gene contains many of the canonical features of highly expressed S. cerevisiae genes. There is considerable sequence similarity between C. tsukubaensis alpha-glucosidase, the rabbit sucrase-isomaltase complex (proSI) and human lysosomal acid alpha-glucosidase. The cloned DNA fragment from C. tsukubaensis contains a second open reading frame (ORF 2) which has the capacity to encode a polypeptide of 170 amino acids. The function and identity of the polypeptide encoded by ORF 2 is not known. 相似文献
104.
Kedir N. Turi Lindsey Romick-Rosendale Tebeb Gebretsadik Miki Watanabe Steven Brunwasser Larry J. Anderson Martin L. Moore Emma K. Larkin Ray Stokes PeeblesJr. Tina V. Hartert 《Metabolomics : Official journal of the Metabolomic Society》2018,14(10):135
Background
Respiratory syncytial virus (RSV) infection in infants causes significant morbidity and is the strongest risk factor associated with asthma. Metabolites, which reflect the interactions between host cell and virus, provide an opportunity to identify the pathways that underlie severe infections and asthma development.Objective
To study metabolic profile differences between infants with RSV infection, and human rhinovirus (HRV) infection, and healthy infants. To compare infant metabolic differences between children who do and do not wheeze.Methods
In a term birth cohort, urine was collected while healthy and during acute viral respiratory infection with RSV and HRV. We used 1H-NMR to identify urinary metabolites. Multivariate and univariate statistics were used to discriminate metabolic profiles of infants with either RSV ARI, or HRV ARI, and healthy infants. Multivariable logistic regression was used to assess the association of urine metabolites with 1st-, 2nd-, and 3rd-year recurrent wheezing.Results
Several metabolites in nicotinate and nicotinamide metabolism pathways were down-regulated in infants with RSV infection compared to healthy controls. There were no significant differences in metabolite profiles between infants with RSV infection and infants with HRV Infection. Alanine was strongly associated with reduced risk of 1st-year wheezing (OR 0.18[0.0, 0.46]) and 2nd-year wheezing (OR 0.31[0.13, 0.73]), while 2-hydroxyisobutyric acid was associated with increased 3rd-year wheezing (OR 5.02[1.49, 16.93]) only among the RSV infected subset.Conclusion
The metabolites associated with infant RSV infection and recurrent-wheezing are indicative of viral takeover of the cellular machinery and resources to enhance virulence, replication, and subversion of the host immune-response, highlighting metabolic pathways important in the pathogenesis of RSV infection and wheeze development.105.
Understanding predator-prey dynamics is an important component of management strategy development for wildlife populations that are directly affected by predation. Ungulates often serve as a significant source of prey for many large mammal predators, and patterns of predation are known to influence population dynamics. Although black bear and wolf diets have been investigated extensively, prey preference has been less commonly examined, especially in analyses that take into account age class (i.e., juvenile and adult) of the ungulate prey. We examined black bear (Ursus americanus), wolf (Canis lupus), and hybrids (Canis spp.) prey preference in Ontario based on the availability of three ungulate species—elk (Cervus elaphus), moose (Alces alces), and white-tailed deer (Odocoileus virginianus). We analyzed the presence of prey items in black bear and wolf scats collected over 3 years by examining prey hair cuticular scale patterns. We applied correction factors to frequencies of occurrence of prey items found in predator scat and related diet composition to the availability of ungulates, determined by fecal pellet transect surveys. In addition, non-ungulate diet items were identified to obtain full diet composition profiles. We found that black bear diet consisted of more than 87% vegetation, and they were opportunistic, not selecting for any particular ungulate species in either adult or juvenile age class. Wolf diet was comprised mainly of ungulates (~?73.2%), muskrat (Ondatra zibethica; ~?8.5%), and beaver (Castor canadensis; ~?14.6%), and although moose were at least 1.5 times more abundant then each of the other ungulate prey species in the study area, wolves preferred elk, using moose less than expected. Although we found black bear diet to be opportunistic during the summer, wolves in our study heavily utilized both juvenile and adult ungulates, however, among ungulate species, displayed preference for elk. The preference displayed by wolves provides insight that wildlife managers can use to guide further investigation and assist with the development of strategies to ensure continued elk reintroduction success, and moose and white-tailed deer population sustainability. 相似文献
106.
Bhumit A. Patel Adrian Gospodarek Michael Larkin Sophia A. Kenrick Mark A. Haverick Nihal Tugcu 《MABS-AUSTIN》2018,10(7):945-950
For many protein therapeutics including monoclonal antibodies, aggregate removal process can be complex and challenging. We evaluated two different process analytical technology (PAT) applications that couple a purification unit performing preparative hydrophobic interaction chromatography (HIC) to a multi-angle light scattering (MALS) system. Using first principle measurements, the MALS detector calculates weight-average molar mass, Mw and can control aggregate levels in purification. The first application uses an in-line MALS to send start/stop fractionation trigger signals directly to the purification unit when preset Mw criteria are met or unmet. This occurs in real-time and eliminates the need for analysis after purification. The second application uses on-line ultra-high performance size-exclusion liquid chromatography to sample from the purification stream, separating the mAb species and confirming their Mw using a µMALS detector. The percent dimer (1.5%) determined by the on-line method is in agreement with the data from the in-line application (Mw increase of approximately 2750 Da). The novel HIC-MALS systems demonstrated here can be used as a powerful tool for real-time aggregate monitoring and control during biologics purification enabling future real time release of biotherapeutics. 相似文献
107.
The use of cell culture for subchromosomal introgressions of barley yellow dwarf virus resistance from Thinopyrum intermedium to wheat. 总被引:7,自引:0,他引:7
P M Banks P J Larkin H S Bariana E S Lagudah R Appels P M Waterhouse R I Brettell X Chen H J Xu Z Y Xin Y T Qian X M Zhou Z M Cheng G H Zhou 《Génome》1995,38(2):395-405
Barley yellow dwarf virus (BYDV) resistance has been transferred to wheat from a group 7 chromosome of Thinopyrum (Agropyron) intermedium. The source of the resistance gene was the L1 disomic addition line, which carries the 7Ai-1 chromosome. The resistance locus is on the long arm of this chromosome. BYDV resistant recombinant lines were identified after three or more generations of selection against a group 7 Th. intermedium short arm marker (red coleoptile) and selection for the presence of BYDV resistance. One recombinant line produced by ph. mutant induced homoeologous pairing and 14 recombinant lines induced by cell culture have been identified. Resistance in seven of the cell culture induced recombinants has been inherited via pollen according to Mendelian segregation ratios for up to eight generations. Meiotic analysis of heterozygotes indicates that the alien chromatin in the cell culture induced recombinants is small enough to allow regular meiotic behaviour. The ph-induced recombinant was less regular in meiosis. A probe, pEleAcc2, originally isolated from Th. elongatum and that hybridizes to dispersed repeated DNA sequences, was utilised to detect Th. intermedium chromatin, which confers resistance to BYDV, in wheat backgrounds. Quantification of these hybridization signals indicated that the translocations involved a portion of alien chromatin that was smaller than the complete long arm of 7Ai-1. Restriction fragment length polymorphism analysis confirmed the loss of the short arm of 7Ai-1 and indicated the retention of segments of the long arm of 7Ai-1. Two 7Ai-1L DNA markers always assorted with the BYDV resistance. A third 7Ai-IL DNA marker was also present in seven of eight recombinants. In all recombinants except TC7, the 7Ai-1L markers replaced the 7DL markers. None of the wheat group 7 markers was missing from TC7. It is concluded that all the resistant lines are the result of recombination with wheat chromosome 7D, except line TC7, which is the result of recombination with an unidentified nongroup 7 chromosome. 相似文献
108.
Grahn D. A.; Heller M. C.; Larkin J. E.; Heller H. C. 《Journal of applied physiology》1996,81(6):2547-2554
Grahn, D. A., M. C. Heller, J. E. Larkin, and H. C. Heller.Appropriate thermal manipulations eliminate tremors in ratsrecovering from halothane anesthesia. J. Appl.Physiol. 81(6): 2547-2554, 1996.Tremors arecommon in mammals emerging from anesthesia. To determine whetherappropriate thermal manipulations immediately before emergence fromanesthesia are sufficient to eliminate these tremors,electroencephalographic (EEG) and electromyographic (EMG) activities,hypothalamic temperature (Thy),and O2 consumption were monitoredin 12 rats recovering from halothane anesthesia under three thermalregimes. EEG and EMG activities were recorded throughout anesthesia andserved as feedback signals for controlling anesthetic depth. Duringanesthesia, Thy was either1) allowed to fall to32-34°C, 2) maintained at37-39°C, or 3) allowed to fall to 32-34°C and then raised to 37-39°C. Whenhypothermic on emergence from anesthesia, all of the animals exhibitedpostanesthetic tremors that persisted untilThy values returned tonormothermia. None of the animals expressed postanesthetic tremors whennormothermic on emergence from anesthesia. In addition, the timebetween emergence from anesthesia (as determined by EEG/EMG parameters)and the initiation of coordinated motor activities was significantlydecreased in the normothermic animals. 相似文献
109.
Functional deficits in medial gastrocnemius grafts in rats: relation to muscle metabolism and beta -AR regulation 总被引:1,自引:0,他引:1
Larkin Lisa M.; Faulkner John A.; Hinkle Richard T.; Hassett Cheryl A.; Supiano Mark A.; Halter Jeffrey B. 《Journal of applied physiology》1997,83(1):67-73
Larkin, Lisa M., John A. Faulkner, Richard T. Hinkle, CherylA. Hassett, Mark A. Supiano, and Jeffrey B. Halter.Functional deficits in medial gastrocnemius grafts in rats:relation to muscle metabolism and -AR regulation.J. Appl. Physiol. 83(1): 67-73, 1997.This study tested the hypothesis that alterations in the metabolic integrity of grafted muscle contribute to its diminished ability to sustain power. Compared with control muscles, muscles studied 120 days after the grafting procedure had lower specific forceand sustained power. The sustained power protocol resulted in adepletion of muscle glycogen in control (83%) and grafted (85%)animals. Grafts had lower pre- and poststimulation glycogen, diminishedcitrate synthase activity, and greater hexokinase activity. Nodifferences were observed in phosphofructokinase activity, glucosetransporter GLUT-4 content, fiber type, -adrenergic-receptor (-AR) density, or binding affinity. Isoproterenol-stimulated adenylyl cyclase activity was lower in grafted vs. control muscle, suggesting an uncoupling of the -AR-effector complex. Thus the diminished ability of the grafted muscle to sustain power may beexplained, in part, by a decrease in energy available from glycogenstores and/or a decrease in oxidative capacity. 相似文献
110.
Indirect Effects of an Existing Wind Energy Facility on Lekking Behavior of Greater Prairie‐Chickens
下载免费PDF全文
![点击此处可从《Ethology : formerly Zeitschrift fur Tierpsychologie》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jennifer A. Smith Cara E. Whalen Mary Bomberger Brown Larkin A. Powell 《Ethology : formerly Zeitschrift fur Tierpsychologie》2016,122(5):419-429
Rapid expansion of the wind energy industry has raised concerns about the potential effects of anthropogenic disturbance on prairie grouse. While efforts have been made to address the effects of wind energy facilities on measures of fitness, their effect on the behaviors of prairie grouse has been largely neglected. To address these concerns, we investigated the effects of an existing wind energy facility in Nebraska that became operational in 2005 on the lekking behavior of male greater prairie‐chickens Tympanuchus cupido pinnatus between March and May 2013. Given the potential for disturbance caused by wind turbine noise to disrupt acoustic communication and thus behavior, we predicted that males at leks close to, compared to far from, the wind energy facility would spend more time in agonistic behaviors, and less in booming displays. Given the potential for wind turbine noise to reduce the number of females attending leks (hereafter ‘female lek attendance’), we also predicted that males at leks close to the wind energy facility would spend more time in non‐breeding behaviors and less time in breeding behaviors than males farther from the facility. Although we found no effect of the wind energy facility on female lek attendance, males at leks closer to the wind energy facility spent less time in non‐breeding behaviors than those at leks farther away. However, distance from the wind energy facility had no effect on time spent performing booming displays, flutter jumps, or in agonistic behaviors. Given that lekking behaviors of males influence mating success, our results may have consequences for the fitness of prairie grouse breeding in the vicinity of wind energy facilities. 相似文献