全文获取类型
收费全文 | 1881篇 |
免费 | 220篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 55篇 |
妇产科学 | 15篇 |
基础医学 | 318篇 |
口腔科学 | 78篇 |
临床医学 | 170篇 |
内科学 | 351篇 |
皮肤病学 | 49篇 |
神经病学 | 228篇 |
特种医学 | 116篇 |
外科学 | 218篇 |
综合类 | 36篇 |
预防医学 | 162篇 |
眼科学 | 19篇 |
药学 | 104篇 |
中国医学 | 1篇 |
肿瘤学 | 192篇 |
出版年
2022年 | 16篇 |
2021年 | 22篇 |
2019年 | 18篇 |
2018年 | 30篇 |
2017年 | 39篇 |
2016年 | 26篇 |
2015年 | 41篇 |
2014年 | 41篇 |
2013年 | 61篇 |
2012年 | 70篇 |
2011年 | 79篇 |
2010年 | 50篇 |
2009年 | 60篇 |
2008年 | 89篇 |
2007年 | 79篇 |
2006年 | 95篇 |
2005年 | 82篇 |
2004年 | 66篇 |
2003年 | 57篇 |
2002年 | 76篇 |
2001年 | 45篇 |
2000年 | 63篇 |
1999年 | 67篇 |
1998年 | 48篇 |
1997年 | 67篇 |
1996年 | 43篇 |
1995年 | 34篇 |
1994年 | 36篇 |
1993年 | 18篇 |
1992年 | 42篇 |
1991年 | 23篇 |
1990年 | 39篇 |
1989年 | 45篇 |
1988年 | 44篇 |
1987年 | 36篇 |
1986年 | 26篇 |
1985年 | 38篇 |
1984年 | 19篇 |
1983年 | 26篇 |
1982年 | 20篇 |
1980年 | 16篇 |
1978年 | 22篇 |
1977年 | 13篇 |
1976年 | 13篇 |
1975年 | 20篇 |
1974年 | 16篇 |
1973年 | 16篇 |
1972年 | 18篇 |
1971年 | 12篇 |
1969年 | 13篇 |
排序方式: 共有2115条查询结果,搜索用时 156 毫秒
21.
Humoral immunity to commensal oral bacteria in human infants: salivary secretory immunoglobulin A antibodies reactive with Streptococcus mitis biovar 1, Streptococcus oralis, Streptococcus mutans, and Enterococcus faecalis during the first two years of life 下载免费PDF全文
Cole MF Bryan S Evans MK Pearce CL Sheridan MJ Sura PA Wientzen RL Bowden GH 《Infection and immunity》1999,67(4):1878-1886
Secretory immunoglobulin A (SIgA) antibodies reactive with the pioneer oral streptococci Streptococcus mitis biovar 1 and Streptococcus oralis, the late oral colonizer Streptococcus mutans, and the pioneer enteric bacterium Enterococcus faecalis in saliva samples from 10 human infants from birth to age 2 years were analyzed. Low levels of salivary SIgA1 and SIgA2 antibodies reactive with whole cells of all four species were detected within the first month after birth, even though S. mutans and E. faecalis were not recovered from the mouths of the infants during the study period. Although there was a fivefold increase in the concentration of SIgA between birth and age 2 years, there were no differences between the concentrations of SIgA1 and SIgA2 antibodies reactive with the four species over this time period. When the concentrations of SIgA1 and SIgA2 antibodies reactive with all four species were normalized to the concentrations of SIgA1 and SIgA2 in saliva, SIgA1 and SIgA2 antibodies reactive with these bacteria showed a significant decrease from birth to 2 years of age. Adsorption of each infant's saliva with cells of one species produced a dramatic reduction of antibodies recognizing the other three species. Sequential adsorption of saliva samples removed all SIgA antibody to the bacteria, indicating that the SIgA antibodies were directed to antigens shared by all four species. The induction by the host of a limited immune response to common antigens that are likely not involved in adherence may be among the mechanisms that commensal streptococci employ to persist in the oral cavity. 相似文献
22.
Quantification of cytomegalovirus in bronchoalveolar lavage fluid after allogeneic marrow transplantation by centrifugation culture. 下载免费PDF全文
M A Slavin C A Gleaves H G Schoch R A Bowden 《Journal of clinical microbiology》1992,30(11):2776-2779
A technique to quantify cytomegalovirus (CMV) by centrifugation culture of bronchoalveolar lavage fluid from marrow transplant recipients was developed. This technique was used to assess the CMV response to antiviral treatment and the relationship between viral load, asymptomatic excretion versus symptomatic infection, and prognosis. Relative to tube cell culture, centrifugation culture of bronchoalveolar lavage fluid was more sensitive than direct fluorescent-antibody staining. It was also a rapid, replicable method for detecting and measuring the amount of CMV. There was no significant difference between viral load at diagnosis and after 9 days of treatment with ganciclovir and intravenous immunoglobulin. Viral load was not predictive of outcome, and there was no difference in amount of virus between patients with asymptomatic CMV excretion and those with CMV pneumonia. The amount of CMV may not be as important as other factors (e.g., host immune response) in the pathogenesis of CMV pneumonia. 相似文献
23.
Hart TC; Bowden DW; Bolyard J; Kula K; Hall K; Wright JT 《Human molecular genetics》1997,6(13):2279-2284
Tricho-dento-osseous syndrome (TDO), MIM# 190320, is transmitted as a
highly penetrant autosomal dominant trait that is characterized by variable
clinical expression. The principal clinical features include kinky/curly
hair in infancy, enamel hypoplasia, taurodontism, as well as increased
thickness and density of cranial bones. Possible genetic linkage has been
reported for TDO with the ABO blood group locus, but the gene defect
remains unknown. We have identified four multiplex families (n = 63, 39
affected, 24 unaffected) from North Carolina segregating TDO. We previously
have excluded a major locus for TDO in the ABO region for these families.
Utilizing a genome-wide search strategy, we obtained conclusive evidence
for linkage of the TDO syndrome locus to markers on chromosome 17q21
(D17S791, Z max = 10.54, Theta = 0.00) with no indication of genetic
heterogeneity. Multipoint analysis suggests the TDO locus is located in a 7
cM chromosomal segment flanked by D17S932 and D17S941. This finding
represents the first step towards isolation and cloning of the TDO gene.
Identification of this gene has important implications for understanding
normal and abnormal craniofacial development of hair, teeth and bone.
相似文献
24.
Irene Boo Alexandra E Fischer Doug Johnson Ruth Chin Maxine Giourouki Mandvi Bharadwaj Scott Bowden Joseph Torresi Heidi Drummer 《Journal of clinical virology》2007,39(4):288-294
BACKGROUND: The role of neutralizing antibody (NAb) in determining response to antiviral therapy has not been established. OBJECTIVE: In this study we have analysed the kinetic's of the NAb response in patients with chronic hepatitis C who received antiviral therapy. STUDY DESIGN: Seventeen patients infected with genotype 1, 2a/c or 3a hepatitis C virus (HCV) were enrolled, eight with a sustained virological response (SVR), five non-responders and four relapsers. RESULTS: The mean NAb titre required to neutralize 50% of the E1E2-pp in patients who achieved an SVR (294+/-S.D. 51), in relapsers (246+/-S.D. 61.7) and non-responders (286+/-S.D. 80.95) did not differ significantly between the patient groups and did not alter during the course of treatment (P>0.01). Genetic variation present before antiviral therapy was analysed by single strand conformation polymorphism (SSCP) and failed to demonstrate a significant difference in the mean number of amplified E1E2 DNA fragments from the serum of patients who achieved an SVR (3.15+/-S.D. 1.53), relapsers (2.8+/-S.D. 1.32) or non-responders (3.69+/-S.D. 1.75). The baseline serum HCV viral loads were also not significantly different between patients who achieved an SVR (1.4 x 10(6) copies/ml; +/-S.D. 2.4 x 10(6)), relapsers (1.3 x 10(7) copies/ml; +/-S.D. 2.4 x 10(7)) and non-responders (1.5 x 10(6) copies/ml; +/-S.D. 1.1 x 10(6)). CONCLUSION: We have shown that neutralizing anti-HCVpp antibody is not associated with response to antiviral therapy. In addition, there was no correlation between baseline virological load, circulating viral quasi-species, NAb titres and final response to treatment. 相似文献
25.
Frataxin is reduced in Friedreich ataxia patients and is associated with mitochondrial membranes 总被引:17,自引:8,他引:17
Campuzano V; Montermini L; Lutz Y; Cova L; Hindelang C; Jiralerspong S; Trottier Y; Kish SJ; Faucheux B; Trouillas P; Authier FJ; Durr A; Mandel JL; Vescovi A; Pandolfo M; Koenig M 《Human molecular genetics》1997,6(11):1771-1780
Friedreich ataxia is a progressive neurodegenerative disorder caused by
loss of function mutations in the frataxin gene. In order to unravel
frataxin function we developed monoclonal antibodies raised against
different regions of the protein. These antibodies detect a processed 18
kDa protein in various human and mouse tissues and cell lines that is
severely reduced in Friedreich ataxia patients. By immunocytofluorescence
and immunocytoelectron microscopy we show that frataxin is located in
mitochondria, associated with the mitochondrial membranes and crests.
Analysis of cellular localization of various truncated forms of frataxin
expressed in cultured cells and evidence of removal of an N-terminal
epitope during protein maturation demonstrated that the mitochondrial
targetting sequence is encoded by the first 20 amino acids. Given the
shared clinical features between Friedreich ataxia, vitamin E deficiency
and some mitochondriopathies, our data suggest that a reduction in frataxin
results in oxidative damage.
相似文献
26.
Dithiothreitol prevents age-associated decrease in oocyte/conceptus viability in vitro 总被引:2,自引:0,他引:2
The present study was designed to ascertain whether the negative effects on
reproductive potential of post-ovulatory ageing in vitro of oocytes can be
prevented by antioxidant therapy. Mouse metaphase II (MII) oocytes were
aged in vitro for 12 h prior to insemination in the presence of varying
concentrations of L-ascorbic acid, 6-methoxy-
2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox), L-cystine
dihydrochloride, ethylenediaminetetraacetic acid (EDTA), beta-
mercaptoethanol and DL-dithiothreitol (DTT). In-vitro ageing of oocytes was
associated with lower fertilization rate, higher proportion of concepti
exhibiting cellular fragmentation at 24 h post-insemination and lower
percentage of concepti reaching the blastocyst stage. Ascorbic acid, Trolox
and EDTA had no effect on cellular fragmentation or potential of oocytes
for development. However, the probability of an oocyte reaching the
blastocyst stage was decreased (P < or = or = 0.05) in oocytes incubated
in the presence of L-cystine (50 and 500 microM) and beta-mercaptoethanol
(5, 50 and 500 microM) when compared to control aged oocytes.
Age-associated cellular fragmentation at 24 h post-insemination was
partially prevented (P < or = 0.05) by incubating oocytes in the
presence of beta-mercaptoethanol (500 microM). DTT (50 and 500 microM)
increased (P < or = 0.05) fertilization rate and number of cells at 81 h
post-insemination to levels similar to those exhibited by control oocytes.
Furthermore, both age-associated fragmentation at 24 h post-insemination (P
< or = 0.05) and decreased potential of oocytes for development to the
blastocyst stage (P < or = 0.05) were prevented, at least in part, by
culturing oocytes in the presence of DTT (50 microM). Although the
mechanism by which DTT exerts its beneficial effects on aged oocytes
remains to be elucidated, it may protect oocytes by preventing oxidation of
free thiol groups and/or altering a redox-independent signalling pathway
that mediates cellular fragmentation and death.
相似文献
27.
Summary Rubella virus (RV)-host cell interactions were examined by indirect immunofluorescence staining using antibodies to viral products and cytoskeletal components as probes. The patterns of immunofluorescence observed with human convalescent sera indicated that in infected Vero cells RV-specified proteins were distributed throughout the rough endoplasmic reticulum with some possible accumulation in the region of the Golgi complex. Viral RNA synthesis, detected with anti-double stranded RNA, appeared to be confined to small, intensely stained foci irregularly distributed in the cytoplasm. When cells were infected at a higher multiplicity, these foci appeared to aggregate into linear arrays. Infection with RV had a profound effect on the organization of actin in both Vero and BHK 21 cells, as shown by anti-actin antibodies. Actin microfilaments were observed to disintegrate progressively into amorphous aggregates of apparently monomeric actin as the infection proceeded. Because of the role actin microfilaments may play in cell mitosis it is postulated that this effect may be related to the inhibition of cell division reported to be associated with the congenital rubella syndrome.With 3 Figures 相似文献
28.
Bruno Amduri Khalid Berrada Bernard Boutevin Michel Mlas Roy D. Bowden 《Macromolecular chemistry and physics.》1993,194(11):3001-3014
The synthesis of novel telechelic monodispersed diols produced from the radical monoaddition of an excess of 10-undecenol with novel α, ω-dithiols, initiated by peroxides, is presented. The telechelic dithiols employed were prepared from nonconjugated dienes and a commercially available dithiol, or by esterification of adipic acid with 2-mercaptoethanol. From these dithiols, the diols were selectively obtained in high yields. Such α, ω-dihydroxylated compounds were characterized by both 1H and 13C NMR spectroscopy. The diol which exhibits the ester functions shows excellent solubility in common organic solvents contrarily to the other ones. The physical properties (Tg, Tm and decomposition temperatures) of these diols were compared and it is noted that the thermostability of these monodispersed telechelic diols is much better than those of the polydispersed commercially available ones such as poly(ethylene glycol)s or poly(tetramethylene glycol)s. 相似文献
29.
Pulmonary reaction to long and short asbestos fibers is independent of fibroblast growth factor production by alveolar macrophages. 总被引:1,自引:2,他引:1 下载免费PDF全文
The role of alveolar macrophage (AM)-derived secretory products in fibroblast stimulation after the instillation of long and short asbestos to rat lungs is now investigated. A pure sample of 1 mg long crocidolite (greater than 2.5 mu) induced pulmonary fibrosis in 8 weeks, but secretions of lavaged AM from these lungs did not enhance growth or collagen synthesis in cultured rat lung fibroblasts. In contrast, the same dose of short fibers did not produce pulmonary fibrosis, although AM lavaged from these lungs were increased in number, had more phagocytized fibers, and when incubated, secreted factors that stimulated fibroblasts in culture. When normal AM were exposed to these fiber samples for 24 hours in vitro, greater phagocytosis of particles occurred and each asbestos fiber sample induced secretion of an AM-derived growth factor for cultured fibroblasts. The results indicate that both long and short fibers are capable of inducing AM to secrete fibrogenic factors in vitro, but in vivo, cytokine secretion by AM into the alveolar spaces in response to short fibers is not associated with stimulation of the interstitial fibroblast. In contrast, pulmonary fibrosis after long fiber administration appears unrelated to an AM secretion and is probably caused by fiber penetration into the peribronchiolar tissue, where interstitial macrophage activation may occur over several weeks. 相似文献
30.
Ultradian rhythms in waking behavior of rhesus monkeys 总被引:1,自引:0,他引:1
D M Bowden D F Kripke D F Kripke V G Wyborney V G Wyborney 《Physiology & behavior》1978,21(6):929-933
The behavior of seven individually housed adult male rhesus monkeys was recorded by time-lapse video, 10 hr per day, for up to 5 days. Recordings were analyzed in 50 sec intervals for the presence or absence of 5 behavior, viz., ingestion, locomotion, exploration, self-grooming, and resting. Analyses were based on the number of 50 sec intervals per 5 min epoch in which each of these behaviors occurred. Variance spectra were computed on each behavior for each animal, and the significance of a prospectively predicted behavioral cyclicity in the frequency band of 12–18 cycles/day was explored with t tests for the group of monkeys. All 5 behaviors exhibited a statistically significant spectral peak as predicted. Significant cross-spectral relationships were found reflecting temporal relationships between ingestion, locomotion, exploration, and resting. The first 3 were in phase with one another and out-of-phase (reciprocal) with resting. Locomotion tended to precede exploration, and exploration to precede ingestion. These results suggest that the 12–24 cycles/day orality rhythm described earlier in monkeys is not discrete, but is one component of a more general 12–18 cycles/day behavioral cycle involving locomotion, exploration, and rest as well. Self-grooming, while perhaps cyclic, was not significantly related to the orality-locomotion-exploration complex. 相似文献