全文获取类型
收费全文 | 522篇 |
免费 | 43篇 |
国内免费 | 17篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 19篇 |
妇产科学 | 6篇 |
基础医学 | 77篇 |
口腔科学 | 52篇 |
临床医学 | 43篇 |
内科学 | 94篇 |
皮肤病学 | 16篇 |
神经病学 | 6篇 |
特种医学 | 94篇 |
外科学 | 54篇 |
综合类 | 27篇 |
预防医学 | 19篇 |
眼科学 | 7篇 |
药学 | 32篇 |
中国医学 | 9篇 |
肿瘤学 | 24篇 |
出版年
2023年 | 4篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 4篇 |
2018年 | 11篇 |
2017年 | 10篇 |
2016年 | 12篇 |
2015年 | 10篇 |
2014年 | 6篇 |
2013年 | 13篇 |
2012年 | 13篇 |
2011年 | 22篇 |
2010年 | 22篇 |
2009年 | 32篇 |
2008年 | 14篇 |
2007年 | 35篇 |
2006年 | 4篇 |
2005年 | 12篇 |
2004年 | 13篇 |
2003年 | 12篇 |
2002年 | 12篇 |
2001年 | 5篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 21篇 |
1997年 | 39篇 |
1996年 | 32篇 |
1995年 | 19篇 |
1994年 | 16篇 |
1993年 | 20篇 |
1992年 | 1篇 |
1991年 | 9篇 |
1990年 | 3篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 11篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 12篇 |
1982年 | 6篇 |
1981年 | 11篇 |
1980年 | 8篇 |
1979年 | 1篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有582条查询结果,搜索用时 11 毫秒
1.
2.
The role of growth factors and cytokines in the impaired healing of chronic leg ulcers remains uncertain. The aim of this study was to determine whether changes in the amount and location of cytokines and growth factors may be associated with impaired healing in chronic leg ulcers. Biopsies from leg ulcers of 21 patients and from normal skin of nine healthy volunteers were examined immunohistochemically for selected growth factors and cytokines. Greater staining intensity was found in keratinocytes at the edges of ulcers compared to normal skin, or skin adjacent to the ulcers. Staining at the ulcer edge was more intense in nonhealing ulcers for only vascular endothelial growth factor and platelet-derived growth factor, whereas staining in the adjacent skin was more intense for all factors in the nonhealing phase. For all factors staining was cytoplasmic, suggesting production in these areas. This study shows up-regulation of the production of cytokines and growth factors in keratinocytes of chronic leg ulcers that is greater when the ulcers are nonhealing. 相似文献
3.
4.
L F Kneipp V F Palmeira A A S Pinheiro C S Alviano S Rozental L R Travassos J R Meyer-Fernandes 《Medical mycology》2003,41(6):469-477
The activity of a phosphatase was characterized in intact mycelial forms of Fonsecaea pedrosoi, a pathogenic fungus that causes chromoblastomycosis. At pH 5.5, this fungus hydrolyzed p-nitrophenylphosphate (p-NPP) to p-nitrophenol (p-NP) at a rate of 12.78 +/- 0.53 nmol p-NP per h per mg hyphal dry weight. The values of Vmax and apparent Km for p-NPP hydrolyses were measured as 17.89 +/- 0.92 nmol p-NP per h per mg hyphal dry weight and 1.57 +/- 0.26 mmol/l, respectively. This activity was inhibited at increased pH, a finding compatible with an acid phosphatase. The enzymatic activity was strongly inhibited by classical inhibitors of acid phosphatases such as sodium orthovanadate (Ki = 4.23 micromol/l), sodium molybdate (Ki = 7.53 micromol/l) and sodium fluoride (Ki = 126.78 micromol/l) in a dose-dependent manner. Levamizole (1 mmol/l) and sodium tartrate (10 mmol/l), had no effect on the enzyme activity. Cytochemical localization of the acid phosphatase showed electrondense cerium phosphate deposits on the cell wall, as visualized by transmission electron microscopy. Phosphatase activity in F. pedrosoi seems to be associated with parasitism, as sclerotic cells, which are the fungal forms mainly detected in chromoblastomycosis lesions, showed much higher activities than conidia and mycelia did. A strain of F. pedrosoi recently isolated from a human case of chromoblastomycosis also showed increased enzyme activity, suggesting that the expression of surface phosphatases may be stimulated by interaction with the host. 相似文献
5.
6.
Picotamide inhibition of excess in vitro thromboxane B2 release by colorectal mucosa in inflammatory bowel disease. 总被引:1,自引:0,他引:1
Collins CE Benson MJ Burnham WR Rampton DS 《Alimentary pharmacology & therapeutics》1996,10(3):315-320
BACKGROUND: Inflammatory bowel disease is associated with increased mucosal release of eicosanoids. Among these, thromboxane A2 has been proposed as a possible inflammatory mediator; its suppression may be a useful therapeutic option. METHODS: Using a tissue incubation technique, we compared release of immunoreactive thromboxane B2 by colonic biopsies from patients with ulcerative colitis, Crohn's disease and controls, and assessed the inhibitory effect of picotamide, a thromboxane synthesis inhibitor-receptor antagonist, which has been widely used in Italy for management of ischaemic heart and cerebrovascular disease. RESULTS: Increased amounts of thromboxane B2 were released from biopsies from patients with active ulcerative colitis (median 238 pg/20 min/mg wet weight (interquartile range 147- 325), n = 12) and active Crohn's disease (252 (174-450), 6) compared with those from patients with quiescent ulcerative colitis (95 (61- 140), 12) or Crohn's disease (105 (57-201), 13), or controls (136 (64- 206), 8). Incubation with picotamide at concentrations between 100 microM and 1 mM reduced thromboxane B2 release (IC50 890 microM). CONCLUSION: Since increased thromboxane A2 production may have pathogenetic importance, thromboxane synthesis inhibitor-receptor antagonists such as picotamide merit therapeutic trial in the management of inflammatory bowel disease. 相似文献
7.
Anderson RA; Evans LW; Irvine DS; McIntyre MA; Groome NP; Riley SC 《Human reproduction (Oxford, England)》1998,13(12):3319-3325
Follistatin is a binding protein for the activin and inhibin family of
hormones, regulating their biological activity. In the male reproductive
tract, the interaction of these factors is likely to be involved in the
regulation of the proliferation of several cell types. We have investigated
the presence of follistatin and activin A in seminal plasma using specific
immunoassays and have localized follistatin and activin/inhibin subunits in
the adult human testis, prostate and seminal vesicle to establish their
likely sources. High concentrations of immunoreactive follistatin were
present in seminal plasma in normal men (mean 97.9 ng/ml; 1.43 ng/ml in
peripheral plasma) and were similar in men with oligo/azoospermia and
following vasectomy. Follistatin immunoreactivity was localized to both
Leydig and Sertoli cells of the testis, and to epithelial cells of the
prostate gland and seminal vesicle, which are likely to be the predominant
sources of the hormone in seminal plasma. Activin A was also present in
seminal plasma in normal men but was undetectable following vasectomy, thus
deriving from the testis. Consistent with this finding, the betaA-subunit
was immunolocalized in Sertoli and Leydig cells but was not present in
seminal vesicle or prostate gland. The functional significance of the high
concentrations of follistatin secreted into seminal plasma by the prostate
gland and/or seminal vesicle is uncertain, but they may regulate the
biological activity of testis-derived activin A and inhibin B.
相似文献
8.
9.
10.
do Valle Matta MA Sales Alviano D dos Santos Silva Couceiro JN Nazareth M Meirelles L Sales Alviano C Angluster J 《Parasitology research》1999,85(4):293-299
The cell-surface expression of sialoglycoconjugate structures in wild-type Crithidia fasciculata and its TFRR1 drug-resistant mutant was analyzed with the aid of an influenza C virus strain, lectin, enzymatic treatment, and flow cytofluorimetry
analysis probed with fluorescein isothiocyanate-labeled (FITC) lectins. 9-O-Acetyl-N-acetyl neuraminic acid (Neu5,9Ac2) structures mediate influenza C virus cell-binding. The SAα2,3Gal and SAα2,6Gal sequences are specifically recognized by
Maackia amurensis (MAA) and Sambucus nigra (SNA) lectins, respectively. On the basis of these param- eters the TFRR1 mutant strain of C. fasciculata was found to contain exposed sialoglycoconjugates bearing Neu5,9Ac2 surface structures. After the removal of sialic acid residues by neuraminidase activity the marked increases in PNA (peanut
agglutinin)-mediated agglutinating activity showed that those acidic units on C. fasciculata cells were glycosidically linked to d-galactose. The bond involves SAα2,6Gal and SAα2,3Gal linkages as suggested by the use of FITC-SNA and FITC-MAA lectins, respectively.
Both SAα2,3Gal and SAα2,6Gal sequences were preferentially expressed by the TFRR1 mutant. The SAα2,6 linkage markedly predominated. In the TFRR1 mutant, but not in wild-type cells, two distinct populations of cells were distinguished by reactivity with FITC-SNA, one
of which was enriched with surface SAα2,6Gal sequences. These diverse findings suggest that sialoglycoconjugate structures
present on the flagellate surface may be associated with mutation and the cell growth cycle in C. fasciculata.
Received: 17 September 1998 / Accepted: 22 October 1998 相似文献