全文获取类型
收费全文 | 643篇 |
免费 | 64篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 11篇 |
2020年 | 8篇 |
2019年 | 12篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 14篇 |
2015年 | 28篇 |
2014年 | 38篇 |
2013年 | 42篇 |
2012年 | 44篇 |
2011年 | 41篇 |
2010年 | 37篇 |
2009年 | 19篇 |
2008年 | 30篇 |
2007年 | 24篇 |
2006年 | 29篇 |
2005年 | 22篇 |
2004年 | 23篇 |
2003年 | 27篇 |
2002年 | 24篇 |
2001年 | 17篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 9篇 |
1997年 | 12篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 11篇 |
1991年 | 6篇 |
1989年 | 9篇 |
1987年 | 3篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1965年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有707条查询结果,搜索用时 31 毫秒
681.
Vanbrabant Lien Braekers Kris Ramaekers Katrien 《Flexible Services and Manufacturing Journal》2021,33(3):783-845
Flexible Services and Manufacturing Journal - Emergency departments (EDs) are continuously exploring opportunities to improve their efficiency. A new opportunity lies in revising the... 相似文献
682.
A case of intramural esophageal hemorrhage in a hemodialysis patient is described. The hemorrhage followed an episode of vomiting and violent retching. Spontaneous resolution occurred with conservative management. The clinical course resembled that of previous case reports of intramural esophageal hemorrhage, whether or not associated with chronic renal failure and intermittent hemodialysis. 相似文献
683.
Pattern recognition receptors are a key component of the first line host defense against infection, recognizing specific microbial products. We hypothesize that monocyte hyporesponsiveness in human sepsis is associated with a downregulation of the pattern recognition receptors Toll-like receptor (TLR)-2 and TLR4. Protein expression of CD14, TLR2 and TLR4 on blood monocytes was examined using flow cytometry from 29 patients with sepsis and 14 healthy controls. In addition LPS stimulated TNF-α and IL-10 production was studied in a 24 hour whole blood assay. We found an increased expression of CD14, TLR2 and TLR4 in patients with sepsis compared to controls (p < 0.01). In patients with sepsis, death was associated with significant lower CD14 and TLR2 expression at admission (CD14: 25.7 +- 19.1 vs 39.1 +- 17.3 mean fluorescence intensity [MFI], p = 0.02; TLR2: 21.8 +- 9.4 vs. 30.9 +- 9.6, p = 0.01). At 72 hours the TLR2 expression on monocytes was associated with the IL-10 inducibility after LPS stimulation (r = 0.52, p = 0.02) and the CD14 expression with the IL-6, IL-10 and TNF inducibility. We conclude that septic patients are characterized by an increased expression of CD14, TLR2 and TLR4 on monocytes compared to controls. Death is associated with downregulation of TLR2 and CD14 expression on monocytes correlating with reduced cytokine inducibility. We suggest that CD14 and TLR2 are a key factor in monocyte hyporesponsibility during severe sepsis. 相似文献
684.
685.
Nhu-Ngoc Nguyen Thi Tuong Vi Tran Quoc-Duy Nguyen Tran-Phong Nguyen Tuyet-Ngan Lien 《Biotechnology progress》2023,39(4):e3344
Bacterial cellulose (BC) is a biopolymer with applications in numerous industries such as food and pharmaceutical sectors. In this study, various hydrocolloids including modified starches (oxidized starch—1404 and hydroxypropyl starch—1440), locust bean gum, xanthan gum (XG), guar gum, and carboxymethyl cellulose were added to the Hestrin-Schramm medium to improve the production performance and microstructure of BC by Gluconacetobacter entanii isolated from coconut water. After 14-day fermentation, medium supplemented with 0.1% carboxymethyl cellulose and 0.1% XG resulted in the highest BC yield with dry BC content of 9.82 and 6.06 g/L, respectively. In addition, scanning electron microscopy showed that all modified films have the characteristic three-dimensional network of cellulose nanofibers with dense structure and low porosity as well as larger fiber size compared to control. X-ray diffraction indicated that BC fortified with carboxymethyl cellulose exhibited lower crystallinity while Fourier infrared spectroscopy showed characteristic peaks of both control and modified BC films. 相似文献
686.
ABSTRACT: BACKGROUND: Rating scales are valuable tools in suicide research and can also be useful supplements to the clinical interview in suicide risk assessments. This study describes the psychometric properties of a Norwegian language version of the Suicide Assessment Scale Self-report version (SUAS-S). METHODS: Participants were fifty-two patients (mean age = 39.3 years, SD = 10.7) with major depression (53.8%), bipolar disorder (25.0%) and/or a personality disorder (63.5%) referred to a psychiatric outpatient clinic. The SUAS-S, the screening section of the Beck Scale for Suicidal Ideation (BSS-5), the Beck Depression Inventory (BDI), Beck's Hopelessness Scale (BHS), the Symptom Check-List-90 R (SCL-90R) and the Clinical Global Impression for Severity of Suicidality (CGI-SS) were administered. One week later, the patients completed the SUAS-S a second time. RESULTS: Cronbach's alpha for SUAS-S was 0.88 and the test-retest reliability was 0.95 (95% CI: 0.93- 0.97). SUAS-S was positively correlated with the BSS-5 (r = 0.66; 95% CI: 0.47-0.85) for the study sample as a whole and for the suicidal (r = 0.52) and non-suicidal groups (r = 0.50) respectively. There was no difference between the SUAS-S and the BSS-5 in the ability to identify suicidality. This ability was more pronounced when the suicide risk was high. There was a substantial intercorrelation between the score on the SUAS-S and the BDI (0.81) and the BHS (0.76). The sensitivity and specificity of the SUAS-S was explored and an appropriate clinical cut-off value was assessed. CONCLUSIONS: The study revealed good internal consistency, test-retest reliability and concurrent validity for the Suicide Assessment Scale Self-report version. The discriminatory ability for suicidality was comparable to that of the BSS-5. 相似文献
687.
688.
A thermostable homodimeric isocitrate dehydrogenase from the hyperthermophilic sulfate-reducing archaeon Archaeoglobus fulgidus was purified and characterized. The mol. mass of the isocitrate dehydrogenase subunit was 42 kDa as determined by SDS-PAGE.
Following separation by SDS-PAGE, A. fulgidus isocitrate dehydrogenase could be renatured and detected in situ by activity staining. The enzyme showed dual coenzyme specificity
with a high preference for NADP+. Optimal temperature for activity was 90° C or above, and a half-life of 22 min was found for the enzyme when incubated at
90° C in a 50 mM Tricine-KOH buffer (pH 8.0). Based on the N-terminal amino acid sequence, the gene encoding the isocitrate
dehydrogenase was cloned. DNA sequencing identified the icd gene as an open reading frame encoding a protein of 412 amino acids with a molecular mass corresponding to that determined
for the purified enzyme. The deduced amino acid sequence closely resembled that of the isocitrate dehydrogenase from the archaeon
Caldococcus noboribetus (59% identity) and bacterial isocitrate dehydrogenases, with 57% identity with isocitrate dehydrogenase from Escherichia coli. All the amino acid residues directly contacting substrate and coenzyme (except Ile-320) in E. coli isocitrate dehydrogenase are conserved in the enzyme from A. fulgidus. The primary structure of A. fulgidus isocitrate dehydrogenase confirmes the presence of Bacteria-type isocitrate dehydrogenases among Archaea. Multiple alignment
of all the available amino acid sequences of di- and multimeric isocitrate dehydrogenases from the three domains of life shows
that they can be divided into three distinct phylogenetic groups.
Received: 6 February 1997 / Accepted: 12 June 1997 相似文献
689.
690.