全文获取类型
收费全文 | 614篇 |
免费 | 53篇 |
出版年
2021年 | 13篇 |
2019年 | 8篇 |
2018年 | 11篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 15篇 |
2014年 | 19篇 |
2013年 | 22篇 |
2012年 | 25篇 |
2011年 | 33篇 |
2010年 | 24篇 |
2009年 | 23篇 |
2008年 | 33篇 |
2007年 | 26篇 |
2006年 | 17篇 |
2005年 | 25篇 |
2004年 | 23篇 |
2003年 | 18篇 |
2002年 | 22篇 |
2001年 | 16篇 |
2000年 | 23篇 |
1999年 | 18篇 |
1998年 | 8篇 |
1997年 | 11篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1993年 | 7篇 |
1992年 | 13篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 11篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 18篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1972年 | 5篇 |
1968年 | 4篇 |
1967年 | 5篇 |
1964年 | 3篇 |
1931年 | 2篇 |
排序方式: 共有667条查询结果,搜索用时 125 毫秒
91.
Jennifer M Medina Tamara C Valovich McLeod Suzanne K Howell Jackie J Kingma 《Journal of electromyography and kinesiology》2008,18(4):591-597
There is a discrepancy between males and females in regards to lower extremity injury rates, particularly at the knee [Agel, J., Arendt, E.A., Bershadsky, B., 2005. Anterior cruciate ligament injury in National Collegiate Athletic Association basketball and soccer: a 13-year review. American Journal of Sports Medicine 33, (4) 524-530]. Gender differences in neuromuscular recruitment characteristics of the muscles that stabilize the knee are often implicated as a factor in this discrepancy. There is considerable research in the area of gender differences in regards to neuromuscular characteristics of the lower extremity in response to perturbation; however, most studies have been performed on the adult population only. Additionally, there is no consensus as to the gender differences that have been demonstrated. The purpose of this study was to compare muscular preactivation of selected lower extremity muscles (vastus medialis, rectus femoris, and medial/lateral hamstrings) in adolescent female basketball athletes, male basketball athletes, and female non-athletes in response to a drop landing. Subjects in the female non-athlete group recruited rectus femoris significantly slower than both the female athlete and male athlete groups (619.9=588.5>200.1ms prior to ground contact). The female non-athlete group also demonstrated a significantly slower vastus medialis compared to the female athlete group (127.1 vs 408.1ms), but not significantly slower than the male athlete group (127.1 vs 275.7ms). There were no differences between female athletes and male athletes for time to initial contraction of any muscle groups. No differences were found among the groups for medial or lateral hamstring activation. This study demonstrates that physical conditioning due to basketball participation appears to affect neuromuscular recruitment in adolescents and reveals a necessity to find alternate methods of training the hamstrings for improved neuromuscular capabilities to prevent injury. 相似文献
92.
Canine model of nasal congestion and allergic rhinitis. 总被引:1,自引:0,他引:1
Ruslan L Tiniakov Olga P Tiniakova Robbie L McLeod John A Hey Donovan B Yeates 《Journal of applied physiology》2003,94(5):1821-1828
The ragweed- and histamine-induced decreases in nasal patency in cohorts of ragweed-sensitized and nonsensitized dogs were assessed. The volume of nasal airways (V(NA)) was assessed by acoustic rhinometry and resistance to airflow (R(NA)) by anterior rhinomanometry. Histamine delivered to the nasal passages of five dogs caused a rapid and prolonged increase in R(NA) (0.75 +/- 0.26 to 3.56 +/- 0.50 cmH(2)O. l(-1). min), an effect that was reversed by intranasal delivery of aerosolized phenylephrine. Ragweed challenge in five ragweed-sensitized dogs increased R(NA) from 0.16 +/- 0.02 to 0.53 +/- 0.07 cmH(2)O. l(-1). min and decreased V(NA) from 12.5 +/- 1.9 to 3.9 +/- 0.3 cm(3), whereas administration of saline aerosol neither increased R(NA) nor decreased V(NA). Prior administration of d-pseudoephedrine (30 mg po) attenuated the ragweed-induced increase in R(NA) and decrease in V(NA). Ragweed challenge changed neither R(NA) nor V(NA) in four nonsensitized dogs. Mediator-induced nasal congestion and allergen-induced allergic rhinitis in ragweed-sensitized dogs, which exhibit symptoms similar to human disease, can be used in the evaluation of safety and efficacy of antiallergic activity of potential drugs. 相似文献
93.
Ray C. Bartolo Natalie Harfoot Mike Gill Kristy Demmers Bernie McLeod A. Grant Butt 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2009,179(8):997-1010
The colon of the brushtail possum does not have an electrogenic secretory response. Given the functional significance of electrogenic
Cl− secretion in the intestine of eutherian mammals, we have investigated the secretory response in the small intestine of this
marsupial. In the Ussing chamber cAMP-dependent secretagogues stimulated a sustained increase in ileal short-circuit current
(Isc), whereas Ca2+-dependent secretagogues induced a transient increase. Both the responses were inhibited by mucosal addition of the anion
channel blocker 5-nitro-2-(3-phenylpropylamino) benzoic acid (100 μmol l−1), consistent with an anion secretory response. However, the responses were not inhibited by serosal bumetanide (10 μmol l−1) and were independent of bath Cl−, indicating that the stimulated ileal Isc does not involve electrogenic Cl− secretion driven by the NaK2Cl cotransporter, NKCC1. Consistent with this, there were low levels of NKCC1 expression in the
ileal epithelium. In particular, NKCC1 expression in the ileal crypt cells was comparable to that of the villous cells. This
differs from eutherian mammals where high levels of NKCC1 expression in the ileal crypt cells are associated with their role
in Cl− secretion. The cAMP- and Ca2+-dependent secretory responses were inhibited by the removal of HCO3
− suggesting that these responses were due to electrogenic HCO3
− secretion. We conclude that the ileum of the possum does not secrete Cl− due to low levels of NKCC1 expression. It does however appear to secrete HCO3
−. These results are further significant examples of differences in the transport function of the possum intestinal epithelium
compared with eutherian mammals. 相似文献
94.
Ginny D. Ho John Anthes Ana Bercovici John P. Caldwell Kuo-Chi Cheng Xiaoming Cui Ahmad Fawzi Xiomara Fernandez William J. Greenlee John Hey Walter Korfmacher Sherry X. Lu Robbie L. McLeod Fay Ng April Smith Torhan Zheng Tan Deen Tulshian Geoffrey B. Varty Xiaoying Xu Hongtao Zhang 《Bioorganic & medicinal chemistry letters》2009,19(9):2519-2523
The discovery of 1 as a high-affinity ligand for the nociceptin receptor has led to the synthesis of a series of tropane (8-methyl-8-azabicyclo[3.2.1]octane) derivatives as optimized ligands. These compounds exhibit high affinity for the nociceptin receptor, moderate to excellent selectivity over the opioid μ receptor, and behave as full agonists. In this Letter, we present the synthesis and highlight the structure–activity relationship of tropane derivatives culminating in the identification of 24 and 32 as potent and orally active antitussive and anxiolytic agents. The in vitro and in vivo activities, pharmacokinetic profile, and the hPXR activity, which predicts the potential 3A4 induction in human, are disclosed. 相似文献
95.
John P. Caldwell Julius J. Matasi Xiomara Fernandez Robbie L. McLeod Hongtao Zhang Ahmad Fawzi Deen B. Tulshian 《Bioorganic & medicinal chemistry letters》2009,19(4):1164-1167
A series of N-8 substituted analogs based upon the spiropiperidine core of the original lead compound 1 was synthesized. This lead has been elaborated to compounds to give compounds 2 and 3 (R = H) that exhibited high NOP binding affinity as well as selectivity against other known opioid receptors. These two series have been further functionalized at the amido nitrogen. The synthesis and structure–activity relationship (SAR) of these and related compounds are discussed. 相似文献
96.
97.
Michelena Pablo; Sibbald Angela M.; Erhard Hans W.; McLeod James E. 《Behavioral ecology》2009,20(1):145-152
Group cohesion in social animals foraging in patchy environmentsdepends on 2 opposite forces, intraspecific competition, andattraction. The decision to leave or stay in a group may varyaccording to the individual personality. We investigated therole of personality when feeding competition increases as aresult of increasing group size. Individuals referred as "bold"and "shy" were identified from an indoor exploration test accordingto their propensity to leave the group to explore a novel environment,using 12 novel objects placed at increasing distances from thegroup. Groups of 2, 4, 6, or 8 shy or bold sheep were testedin 45 x 5–m grass arenas, with one 5 x 5–m patchof preferred vegetation at each end. Sheep grazed on or closeto these patches, but the number grazing the patches seldomreached more than 4–5 individuals, suggesting that crowdingmight affect foraging at the highest densities. The smallestgroups grazed together on the same patch, but there was an increasinglikelihood of splitting into subgroups as group size increased,with equal-sized subgroups most commonly grazing the 2 patchessimultaneously. This effect was greatest in bold sheep, whichtended to split into subgroups at smaller group sizes than shysheep. This study provides new insight into the mechanisms bywhich group-living herbivores distribute themselves across patchyresources in a way that minimizes interference competition anddemonstrates the importance of individual variability for spatialorganization at the level of the group. 相似文献
98.
The protozoan parasite Toxoplasma gondii is an important cause of ocular disease both in immunosuppressed and immunocompetent individuals. Non-ocular infections are not usually serious in otherwise healthy adults. In contrast, toxoplasmic retinochoroiditis is a progressive, recurring disease that can cause severe morbidity. Here, Fiona Roberts and Rima McLeod review the demography, pathology and clinical findings of this disease. They discuss mechanisms of retinal destruction and disease recurrences, and the local immunological response at this immune-privileged site. 相似文献
99.
100.
Ewald SJ Kapczynski DR Livant EJ Suarez DL Ralph J McLeod S Miller C 《Immunogenetics》2011,63(6):363-375