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排序方式: 共有655条查询结果,搜索用时 15 毫秒
1.
Factors influencing women to undergo screening mammography 总被引:2,自引:0,他引:2
2.
Braffman BH; Coleman BG; Ramchandani P; Arger PH; Nodine CF; Dinsmore BJ; Louie A; Betsch SE 《Radiology》1994,190(3):797
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Rupture of the distal biceps tendon: evaluation with MR imaging 总被引:2,自引:0,他引:2
5.
Jari-Petteri Tolvanen Kirsimarja Sallinen Xiumin Wu Mika Khnen Pertti Arvola Ilkka Prsti 《Basic & clinical pharmacology & toxicology》1998,83(2):75-82
Abstract: We examined the control of vascular tone in rat main superior mesenteric artery. Three standard rings (3 mm in length) of the mesenteric artery were cut, beginning 5 mm, 13 mm and 21 mm distally from the mesenteric arteryaorta junction. In noradrenaline-precontracted rings, relaxations to acetylcholine in the absence and presence of the cyclooxygenase inhibitor diclofenac, did not differ in the studied sections. However, the nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester, attenuated the diclofenac-resistant responses to acetylcholine more effectively in the proximal than the distal section. Glibenclamide, an inhibitor of ATP-sensitive K+ channels, diminished relaxations evoked by acetylcholine only in the distal section, whereas the inhibitor of Ca2+ activated K+ channels, apamin, attenuated the responses in all sections. Furthermore, relaxation sensitivity to nitroprusside and isoprenaline was lower in the proximal than distal section. Arterial contractile sensitivity to noradrenaline and potassium chloride was higher, while the maximal contractile force generation was lower in the proximal than the distal part. In conclusion, in different sections of rat main superior mesenteric artery considerable variability was observed in vasoconstrictor and vasodilator responses, as well as in the contribution of endothelial nitric oxide and endothelium-mediated hyperpolarization to vasodilation. Therefore, the present results emphasize the fact that only corresponding vessel segments should be used when investigating the control of arterial tone. 相似文献
6.
Androgen receptor YAC transgenic mice carrying CAG 45 alleles show trinucleotide repeat instability 总被引:1,自引:15,他引:1
La Spada AR; Peterson KR; Meadows SA; McClain ME; Jeng G; Chmelar RS; Haugen HA; Chen K; Singer MJ; Moore D; Trask BJ; Fischbeck KH; Clegg CH; McKnight GS 《Human molecular genetics》1998,7(6):959-967
X-linked spinal and bulbar muscular atrophy (SBMA) is caused by a CAG
repeat expansion in the first exon of the androgen receptor (AR) gene.
Disease-associated alleles (37-66 CAGs) change in length when transmitted
from parents to offspring, with a significantly greater tendency to shift
size when inherited paternally. As transgenic mice carrying human AR cDNAs
with 45 and 66 CAG repeats do not display repeat instability, we attempted
to model trinucleotide repeat instability by generating transgenic mice
with yeast artificial chromosomes (YACs) carrying AR CAG repeat expansions
in their genomic context. Studies of independent lines of AR YAC transgenic
mice with CAG 45 alleles reveal intergenerational instability at an overall
rate of approximately 10%. We also find that the 45 CAG repeat tracts are
significantly more unstable with maternal transmission and as the
transmitting mother ages. Of all the CAG/CTG repeat transgenic mice
produced to date the AR YAC CAG 45 mice are unstable with the smallest
trinucleotide repeat mutations, suggesting that the length threshold for
repeat instability in the mouse may be lowered by including the appropriate
flanking human DNA sequences. By sequence-tagged site content analysis and
long range mapping we determined that one unstable transgenic line has
integrated an approximately 70 kb segment of the AR locus due to
fragmentation of the AR YAC. Identification of the cis - acting elements
that permit CAG tract instability and the trans -acting factors that
modulate repeat instability in the AR YAC CAG 45 mice may provide insights
into the molecular basis of trinucleotide repeat instability in humans.
相似文献
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8.
Increased expression of telomerase RNA component is associated with increased cell proliferation in human astrocytomas. 总被引:7,自引:1,他引:7
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P. Sallinen H. Miettinen S. L. Sallinen H. Haapasalo H. Helin J. Kononen 《The American journal of pathology》1997,150(4):1159-1164
Deregulation of telomerase, a ribonucleoprotein polymerase that compensates progressive loss of telomeric (TTAGGG)n repeats during DNA replication, has been suggested to facilitate tumorigenesis and cellular immortality by providing unlimited proliferation capacity for cancer cells. We investigated the relationship between tumor proliferation activity and in situ expression of the telomerase RNA component in 46 human grade I to IV astrocytomas. Heterogeneously distributed telomerase RNA expression was detected from all of the tumor samples as well as from normal human brain tissue. However, expression of telomerase RNA was significantly increased in highly malignant tumors (P = 0.024) and in tumors that showed increased proliferation activity determined by MIB-1 immunohistochemistry (P = 0.014). Interestingly, increased telomerase RNA levels were observed in a subgroup of grade II astrocytomas that showed significant increase in proliferation activity (P = 0.047), indicating that the telomerase RNA component is up-regulated already in early states of astrocytoma malignancy. Telomeric repeats amplification assays revealed telomerase activity in 4 of 6 glioblastomas and in 1 rapidly proliferating grade II astrocytoma. These results suggest that increased tumor proliferation activity triggers telomerase activation via mechanisms that involve increased production of the telomerase RNA component. 相似文献
9.
Sallinen M Härmä M Mutanen P Ranta R Virkkala J Müller K 《Journal of sleep research》2003,12(2):103-112
Sleep in shift work has been studied extensively in regular shift systems but to a lesser degree in irregular shifts. Our main aim was to examine the sleep-wake rhythm in shift combinations ending with the night or the morning shift in two irregular shift systems. Three weeks' sleep/work shift diary data, collected from 126 randomly selected train drivers and 104 traffic controllers, were used in statistical analyses including a linear mixed model and a generalized linear model for repeated measurements. The results showed that the sleep-wake rhythm was significantly affected by the shift combinations. The main sleep period before the first night shift shortened by about 2 h when the morning shift immediately preceded the night shift as compared with the combination containing at least 36 h of free time before the night shift (reference combination). The main sleep period before the night shift was most curtailed between two night shifts, on average by 2.9 and 3.5 h among the drivers and the controllers, respectively, as compared with the reference combination. Afternoon napping increased when the morning or the day shift immediately preceded the night shift, the odds being 4.35-4.84 in comparison with the reference combination. The main sleep period before the morning shift became 0.5 h shorter when the evening shift preceded the morning shift in comparison with the sleep period after a free day. The risk for dozing off during the shift was associated only with the shift length, increasing by 17 and 35% for each working hour in the morning and the night shift, respectively. The results demonstrate advantageous and disadvantageous shift combinations in relation to sleep and make it possible to improve the ergonomy of irregular shift systems. 相似文献
10.