全文获取类型
收费全文 | 830篇 |
免费 | 45篇 |
国内免费 | 14篇 |
专业分类
889篇 |
出版年
2024年 | 4篇 |
2023年 | 4篇 |
2022年 | 12篇 |
2021年 | 16篇 |
2020年 | 18篇 |
2019年 | 20篇 |
2018年 | 10篇 |
2017年 | 13篇 |
2016年 | 25篇 |
2015年 | 42篇 |
2014年 | 57篇 |
2013年 | 52篇 |
2012年 | 61篇 |
2011年 | 66篇 |
2010年 | 42篇 |
2009年 | 40篇 |
2008年 | 41篇 |
2007年 | 32篇 |
2006年 | 27篇 |
2005年 | 45篇 |
2004年 | 41篇 |
2003年 | 27篇 |
2002年 | 21篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 12篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1982年 | 7篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1974年 | 3篇 |
1973年 | 7篇 |
1968年 | 4篇 |
1958年 | 2篇 |
排序方式: 共有889条查询结果,搜索用时 0 毫秒
1.
Objective
To determine the frequency of lost to follow-up (LTFU) in the setting of usual care for outpatients with rheumatic diseases including RA, SLE, AS, and Ps/PsA, to explore the associated demographic factors, and to investigate the reasons for being LTFU from the original medical care.Methods
Patients registered between May 2011 and January 2014 at the rheumatology outpatient department of a medical center were included. Those who did not attend their scheduled appointment were defined as LTFU. Univariate and multivariate logistic regression were used to analyze the factors for being LTFU.Results
A total of 781 patients were enrolled, including 406 patients with RA, 174 with SLE, 136 with AS, and 65 with Ps/PsA. The frequency of LTFU was 23.9%, 25.9%, 35.3%, and 35.4%, respectively. The frequency of LTFU was significantly different between the four rheumatic diseases (p = 0.028). In multivariate logistic regression analysis, an older age increased being LTFU in the patients with RA (OR 1.02; 95% CI 1.00–1.04; p = 0.033), but reduced being LTFU in those with Ps/PsA (OR 0.96; 95% CI 0.92–0.99; p = 0.021). Female patients with SLE and Ps/PsA were more likely to be LTFU, although this did not reach statistical significance (p = 0.056 and 0.071, respectively). The most common reason for being LTFU was moving to other district hospitals from the original medical center due to convenience for the patients with RA and SLE, and stopping medication due to minimal symptoms for the patients with AS and Ps/PsA.Conclusions
The frequency of LTFU in patients with rheumatic diseases is high. Associated demographic factors included older age in RA, female gender in SLE and Ps/PsA, and younger age in Ps/PsA, with various reasons for being LTFU. Recognizing these associated factors and reasons for being LTFU may help to improve the attendance of patients and the quality of medical care. 相似文献2.
Bwee Tien Poll-The Ola H. Skjeldal Oddvar Stokke Alf Poulos France Demaugre Jean-Marie Saudubray 《Human genetics》1989,81(2):175-181
Summary We have measured the production of 14CO2 from exogenous [1-14C] phytanic acid in fibroblast monolayers from patients with classical Refsum's disease and peroxisomal disorders. Activities in the different disorders were (percentage of control): classical Refsum's disease (5%), isolated peroxisomal acyl-CoA oxidase deficiency (75%), Zellweger syndrome (4%), neonatal adrenoleukodystrophy (5%), and rhizomelic chondrodysplasia punctate (3%). Absence of complementation was demonstrated between Zellweger syndrome and infantile Refsum's disease lines after polyethylene glycol fusion, with decreases of average activity of 11% relative to unfused cell mixtures. Classical Refsum's disease, rhizomelic chondrodysplasia punctata, and neonatal adrenoleukodystrophy lines all complemented one another, and Zellweger syndrome or infantile Refsum's disease lines, with average activity increases of 522%–772%. No intragenic complementation was observed within either group. Four complementation groups were detected suggesting that at least four genes are involved in phytanic acid -oxidation: one gene for the enzyme phytanic acid -hydroxylase (probably mitochondrial); one gene for a regulatory factor for the expression of phytanic acid -decarboxylation activity and two membrane-bound peroxisomal enzymes involved in the synthesis of plasmalogens; two genes for the assembly of functional peroxisomes and/or import of proteins into peroxisomes. 相似文献
3.
A new temperate wood bamboo endemic to Vietnam is described and illustrated as Chimonocalamus bidoupensis N.H.Nghia & V.T.Tran. The new species is similar to C. baviensis in general appearance, but differs by its densely ciliate culms, culm sheaths that are concave at the apex with dense, white hairs on the abaxial surface of the sheath, and perfect florets 7–8 mm long. 相似文献
4.
Phung Khanh Lam Dong Thi Hoai Tam Nguyen Minh Dung Nguyen Thi Hanh Tien Nguyen Tan Thanh Kieu Cameron Simmons Jeremy Farrar Bridget Wills Marcel Wolbers 《PloS one》2015,10(5)
PurposeTo identify risk factors and develop a prediction model for the development of profound and recurrent shock amongst children presenting with dengue shock syndrome (DSS)MethodsWe analyzed data from a prospective cohort of children with DSS recruited at the Paediatric Intensive Care Unit of the Hospital for Tropical Disease in Ho Chi Minh City, Vietnam. The primary endpoint was “profound DSS”, defined as ≥2 recurrent shock episodes (for subjects presenting in compensated shock), or ≥1 recurrent shock episodes (for subjects presenting initially with decompensated/hypotensive shock), and/or requirement for inotropic support. Recurrent shock was evaluated as a secondary endpoint. Risk factors were pre-defined clinical and laboratory variables collected at the time of presentation with shock. Prognostic model development was based on logistic regression and compared to several alternative approaches.ResultsThe analysis population included 1207 children of whom 222 (18%) progressed to “profound DSS” and 433 (36%) had recurrent shock. Independent risk factors for both endpoints included younger age, earlier presentation, higher pulse rate, higher temperature, higher haematocrit and, for females, worse hemodynamic status at presentation. The final prognostic model for “profound DSS” showed acceptable discrimination (AUC=0.69 for internal validation) and calibration and is presented as a simple score-chart.ConclusionsSeveral risk factors for development of profound or recurrent shock among children presenting with DSS were identified. The score-chart derived from the prognostic models should improve triage and management of children presenting with DSS in dengue-endemic areas. 相似文献
5.
Lignin and veratryl alcohol are not inducers of the ligninolytic system of Phanerochaete chrysosporium. 总被引:1,自引:4,他引:1
下载免费PDF全文

Phanerochaete chrysosporium is a white rot fungus which secretes a family of lignin-degrading enzymes under nutrient limitation. In this work, we investigated the roles of veratryl alcohol and lignin in the ligninolytic system of P. chrysosporium BKM-F-1767 cultures grown under nitrogen-limited conditions. Cultures supplemented with 0.4 to 2 mM veratryl alcohol showed increased lignin peroxidase activity. Addition of veratryl alcohol had no effect on Mn-dependent peroxidase activity and inhibited glyoxal oxidase activity. Azure-casein analysis of acidic proteases in the extracellular fluid showed that protease activity decreased during the early stages of secondary metabolism while lignin peroxidase activity was at its peak, suggesting that proteolysis was not involved in the regulation of lignin peroxidase activity during early secondary metabolism. In cultures supplemented with lignin or veratryl alcohol, no induction of mRNA coding for lignin peroxidase H2 or H8 was observed. Veratryl alcohol protected lignin peroxidase isozymes H2 and H8 from inactivation by H2O2. We conclude that veratryl alcohol acts as a stabilizer of lignin peroxidase activity and not as an inducer of lignin peroxidase synthesis. 相似文献
6.
7.
8.
<正>翼手目为哺乳动物中的第二大目,中国的翼手目多样性也在不断更新,Smith和解焱(2009)统计中国翼手目118种,蒋志刚等(2015)则认为中国翼手目有7科34属134种。广东省翼手目有6科24属55种(邹发生和叶冠锋,2016),此后也仍陆续有新纪录,如长指鼠耳蝠(Myotis longipes)(张琴等,2017)、卡氏伏翼(Hypsugo cadornae)(Xie et al., 2021);我们前期对澳门翼手目的调查,发现5科8属10种(黄继展等,2013)。 相似文献
9.
10.
Everitt AB Luu T Cromer B Tierney ML Birnir B Olsen RW Gage PW 《The Journal of biological chemistry》2004,279(21):21701-21706
High conductance gamma-aminobutyric acid type A (GABA(A)) channels (>40 picosiemens (pS)) have been reported in some studies on GABA(A) channels in situ but not in others, whereas recombinant GABA(A) channels do not appear to display conductances above 40 pS. Furthermore, the conductance of some native GABA(A) channels can be increased by diazepam or pentobarbital, which are effects not reported for expressed GABA(A) channels. GABARAP, a protein associated with native GABA(A) channels, has been reported to cause clustering of GABA(A) receptors and changes in channel kinetics. We have recorded single channel currents activated by GABA in L929 cells expressing alpha(1), beta(1), and gamma(2S) subunits of human GABA(A) receptors. Channel conductance was never higher than 40 pS and was not significantly increased by diazepam or pentobarbital, although open probability was increased. In contrast, in cells expressing the same three subunits together with GABARAP, channel conductance could be significantly higher than 40 pS, and channel conductance was increased by diazepam and pentobarbital. GABARAP caused clustering of receptors in L929 cells, and we suggest that there may be interactions between subunits of clustered GABA(A) receptors that make them open co-operatively to give high conductance "channels." Recombinant channels may require the influence of GABARAP and perhaps other intracellular proteins to adopt a fuller repertoire of properties of native channels. 相似文献