全文获取类型
收费全文 | 252篇 |
免费 | 19篇 |
专业分类
儿科学 | 5篇 |
基础医学 | 46篇 |
口腔科学 | 3篇 |
临床医学 | 12篇 |
内科学 | 31篇 |
皮肤病学 | 1篇 |
神经病学 | 8篇 |
特种医学 | 51篇 |
外科学 | 8篇 |
综合类 | 47篇 |
预防医学 | 40篇 |
眼科学 | 1篇 |
药学 | 8篇 |
肿瘤学 | 10篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2012年 | 8篇 |
2011年 | 7篇 |
2010年 | 3篇 |
2009年 | 11篇 |
2008年 | 6篇 |
2007年 | 12篇 |
2006年 | 10篇 |
2005年 | 16篇 |
2004年 | 19篇 |
2003年 | 9篇 |
2002年 | 14篇 |
2001年 | 14篇 |
2000年 | 10篇 |
1999年 | 15篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 11篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有271条查询结果,搜索用时 15 毫秒
51.
A double-masked study of timolol and pilocarpine combined 总被引:2,自引:0,他引:2
P J Airaksinen R Valkonen T Stenborg K Takki A Klemetti M Kontkanen P Oskala 《American journal of ophthalmology》1987,104(6):587-590
In a double-masked, randomized, multicenter study, 25 patients received timolol 0.5%-pilocarpine 2% twice a day, 25 received timolol 0.5%-pilocarpine 4% twice a day, and 25 received pilocarpine 4% four times a day. The combination drugs showed an immediate, significant reduction in intraocular pressure of 7.2 mm Hg (25%) and 10.7 mm Hg (37%), respectively. The lowered intraocular pressure level was maintained throughout the three-week test period. With pilocarpine alone, intraocular pressure was reduced 5.3 mm Hg (19%). The mean intraocular pressure 12 hours after the last dose compared to two hours after the last dose was significantly higher both in patients receiving pilocarpine four times a day and in patients receiving timolol 0.5%-pilocarpine 4% twice a day (5.1 and 3.6 mm Hg, respectively), but not in patients receiving timolol 0.5%-pilocarpine 2% twice a day (2.6 mm Hg). 相似文献
52.
Indications for breast imaging in women under age 35 years 总被引:1,自引:0,他引:1
To determine appropriate indications for breast imaging in young women, the authors correlated patient histories with mammographic and/or sonographic findings and biopsy or follow-up results for 625 patients aged 13-34 years. The only important indications were a palpable mass and suspicion of an abscess. Of the 335 studies performed for evaluation of a palpable mass, 184 (55%) were normal, 28 (8%) were compatible with benign disease, and 123 (37%) were suggestive of malignancy. Biopsies were performed in 73 patients; the findings were benign in 67 cases, and carcinoma was found in six. Imaging studies were considered helpful in four of the 15 cases of suspected abscess, in that the studies established the presence and extent of an abscess. Studies in 275 women were performed for a variety of other indications. The findings were normal in 239 (87%) studies, benign in 21 (8%), and suggestive of malignancy in 15 (5%); there were no known carcinomas in any of the patients. Women with the "low-yield" indications identified in this study should be followed up clinically rather than referred for imaging studies. 相似文献
53.
Summary. The sequence variability of Barley yellow dwarf virus-PAV (PAV) and Barley yellow dwarf virus-MAV (MAV) was studied by comparing 502 nucleotides from the coat protein-encoding region of six isolates from Latvia and four from Sweden. The diversity within MAV was low (>97% sequence identity), also when compared to isolates from USA and China. In contrast, the variability among PAV isolates was greater and phylogenetic analysis including isolates of a wide geographic origin detected two major clusters, of which both contained isolates from Latvia and Sweden. A new distinct variant of BYDV-PAV was discovered in Latvia, and because of the sequence difference it is proposed to belong to a new species (BYDV-OYV). 相似文献
54.
Identification of the N-acetylneuraminyllactose-specific laminin-binding protein of Helicobacter pylori. 总被引:4,自引:0,他引:4 下载免费PDF全文
The interaction of the gastroduodenal pathogen Helicobacter pylori with the glycoprotein laminin was investigated. Binding of 125I-radiolabelled laminin in a liquid-phase assay by both hemagglutinating and poorly hemagglutinating strains was rapid, saturable, specific, partially reversible, of high affinity, and insensitive to pH. Inhibition of laminin binding by fetuin, but not asialofetuin, and reduced bacterial binding to periodate- or sialidase-treated laminin indicated that glycosylation, particularly sialylation, was important for laminin binding by H. pylori. Inhibition experiments with monosaccharides, disaccharides, and trisaccharides showed that the strains bound to a region spanning a trisaccharide. In particular, inhibition and displacement studies showed that binding to the trisaccharide N-acetylneuraminyl-alpha(2-3)-lactose [NeuAc(2-3)Lac] was preferential to that to the NeuAc(2-6)Lac isomer. Complete inhibition of laminin binding by both hemagglutinating and poorly hemagglutinating strains was achieved only when isolated lipopolysaccharide (LPS) was used as an inhibitor in combination with heat or protease treatment of H. pylori cells, thereby confirming the involvement of both LPS and a protein adhesin in laminin binding. Further inhibition experiments indicated that the protein receptor, rather than LPS, on H. pylori bound NeuAc(2-3)Lac. By using a Western blotting procedure, a 25-kDa outer membrane protein was identified as mediating laminin binding by both hemagglutinating and poorly hemagglutinating H. pylori strains. The specificity of binding was confirmed by complete inhibition of laminin binding by the 25-kDa protein with NeuAc(2-3)Lac. The data collectively suggest that a 25-kDa outer membrane protein acts in a lectin-like manner with LPS to mediate attachment of H. pylori to laminin. 相似文献
55.
Comparison of the complete sequences of five different isolates of Potato virus A (PVA), genus Potyvirus 总被引:2,自引:0,他引:2
Kekarainen T Merits A Oruetxebarria I Rajamäki M Valkonen JP 《Archives of virology》1999,144(12):2355-2366
Summary. The complete nucleotide (nt) and deduced amino acid (aa) sequences of isolates Ali, U, Her (from potato, Solanum tuberosum) and TamMV (from tamarillo, Solanum betacea) of Potato virus A (PVA, genus Potyvirus) were determined and compared with the previously reported sequence of PVA isolate B11. Most parts (proteins) of the polyprotein
showed over 95% aa sequence similarity. The cylindrical inclusion (CI) protein and the 6K 1 protein were the most conserved
proteins among the five isolates. TamMV was the most different isolate. Sequence similarity between TamMV and the other isolates
was the lowest in regions close to the 5′-end [5′-non-translated region (NTR) and P1 region] and 3′-end (N-terminus of coat
protein) of the genome. However, the termini of the genome (the first 60 nt of the 5′-NTR and the entire 3′-NTR) were highly
similar in all five isolates. A frameshift region in the replicase (NIb) was identified the PVA isolates Ali, B11, Her and
U, as compared to TamMV and other potyviruses.
Received May 25, 1999/Accepted July 23, 1999 相似文献
56.
Sequence comparisons suggest that the RNA-dependent RNA polymerase (NIb) of potyviruses and bymoviruses, as well as the viral polymerase of potexviruses may contain a putative retinoblastoma protein (pRb) binding motif. The possibility that the potyviral NIb may function in the nucleus through interactions with plant pRb-related (RBR) proteins, and the modifications of the cell cycle was investigated by a combination of mutagenesis of the NIb and yeast two-hybrid system (YTHS). Mutation of a highly conserved glutamic acid residue in the putative pRb-binding motif of the NIb had no detectable phenotypic effect on replication of Potato virus A (PVA). Furthermore, the NIb proteins from Potato virus V and PVA failed to interact with maize or tobacco RBR proteins in yeast. Although the conservation of the motif for pRb interaction in plant RNA viruses is intriguing, these proteins from plant RNA viruses appear not to interact with plant RBR proteins. 相似文献
57.
D. R. Mbanzibwa Y. P. Tian A. K. Tugume S. B. Mukasa F. Tairo S. Kyamanywa A. Kullaya Jari P. T. Valkonen 《Archives of virology》2009,154(2):353-359
Six isolates of Cassava brown streak virus (CBSV, genus Ipomovirus; Potyviridae) from the Lake Victoria basin in Uganda and Tanzania were characterized. Virus particles were 650 nm long. The complete coat
protein (CP)-encoding sequences (1,101 nucleotides, nt) were 90.7–99.5 and 93.7–99.5% identical at the nt and amino acid (aa)
levels, respectively. The 3′ untranslated region was 225, 226 or 227 nt long. These eight isolates were only 75.8–77.5% (nt)
and 87.0–89.9% (aa) identical when compared to the partial CP sequences (714 nt) of six CBSV isolates characterized previously
from the costal lowlands of Tanzania and Mozambique. Hence, two genetically different and geographically separated populations
of CSBV exist in East Africa. 相似文献
58.
The complete genomic sequence of an isolate of Tobacco vein banding mosaic virus (TVBMV-YND) from Yunnan, China was determined by sequencing overlapping cDNA fragments obtained by RT-PCR with degenerate
and/or specific primers. The genome is composed of 9,570 nucleotides (nt) excluding the 3′-terminal poly (A) tail and contains
one single open reading frame of 9,240 nt encoding a large polyprotein of 3,079 amino acids with predicted Mr of 348.6 kDa.
Phylogenetic analysis of complete genomic sequences confirmed that TVBMV is a distinct species of the genus Potyvirus. Different parts of TVBMV-YND genome shared different levels of identity with other species of potyviruses, while most parts
showed greatest identity with Chilli veinal mottle virus among the potyviruses with available complete genomic sequences. TVBMV-YND had a rare Q/N cleavage site for NIb/CP and uncommon
RITC motif in HC-Pro that is crucial for aphid transmission of potyviruses.
Xiao-Qing Yu and Yu-Fei Lan contributed equally to this research 相似文献
59.
T J Suutari K H Valkonen T J Karttunen B M Ehn B Ekstrand U Bengtsson V Virtanen M Nieminen J Kokkonen 《Journal of investigational allergology & clinical immunology》2006,16(5):296-302
BACKGROUND: Allergic reactions to cow's milk are common in small children. One of the main protein allergens found in cow's milk is beta-lactoglobulin (beta-Lg). Reindeer and bovine milk both contain related beta-Lg proteins, but the allergenicity of reindeer beta-Lg has not previously been studied. The purpose of this study was to analyze the immunological cross-reactivity of IgE antibodies from children with cow's milk allergy to reindeer and bovine beta-Lg. METHODS: Sera from 17 children and a serum pool of 4 patients with elevated cow's milk-specific IgE were investigated. Beta-Lg from bovine and reindeer milk was isolated in native form and an enzyme-linked immunosorbent inhibition assay was developed. Bovine beta-Lg was used as a capturing antigen and the inhibiting effects of reindeer and bovine beta-Lg on the IgE binding were measured. RESULTS: Cross-reactivity patterns of bovine milk beta-Lg specific IgE to reindeer beta-Lg varied among patients. In general, reindeer beta-Lg showed significantly lower inhibition (mean 43%) of IgE binding to the capturing antigen than did bovine beta-Lg (mean 89%). In some patients, even high concentrations of reindeer beta-Lg only partly eliminated the IgE binding to bovine beta-Lg. CONCLUSIONS: The partial cross-reactivity of human anti-bovine IgE with reindeer beta-Lg suggests that it lacks important bovine epitopes and those that are recognized are only weakly bound. 相似文献
60.
Soluble kit receptor in human serum 总被引:3,自引:1,他引:3
Wypych J; Bennett LG; Schwartz MG; Clogston CL; Lu HS; Broudy VC; Bartley TD; Parker VP; Langley KE 《Blood》1995,85(1):66-73
c-kit encodes the transmembrane receptor tyrosine kinase (Kit) for the recently described ligand stem cell factor (SCF). We have developed an enzyme-linked immunosorbent assay for measuring soluble human Kit and we have used the assay to show high levels of soluble Kit in human serum. The distribution of soluble Kit levels was investigated among 112 normal human serum donors. The mean serum level (+/- SD) was found to be 324 +/- 105 ng/mL with the values falling between 163 ng/mL and 788 ng/mL. No correlation between soluble Kit levels and the sexes or ages of the donors was found. Partial purification using immunoaffinity chromatography allowed us to characterize the soluble Kit from pooled human serum. Antibodies generated to a 497-amino acid recombinant human soluble Kit corresponding to the N-terminal extracellular domain of the receptor recognized the serum-derived soluble Kit by immunoblotting. We found that the serum-derived soluble Kit is glycosylated, with mostly N- linked but also O-linked carbohydrate, and with terminal sialic acid residues. When compared with the recombinant human soluble Kit, the serum-derived material was similar both in size and glycosylation pattern. CNBr cleavage of the isolated serum-derived material followed by amino terminal sequencing confirmed the presence of five peptides expected for the extracellular portion of the Kit molecule. The immunoaffinity purified serum-derived soluble Kit inhibited binding of [125I]SCF to membrane-bound receptor in an in vitro assay. These results indicate that soluble Kit could modulate the activity and functions of SCF in vivo. 相似文献