全文获取类型
收费全文 | 3453篇 |
免费 | 185篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 17篇 |
儿科学 | 157篇 |
妇产科学 | 76篇 |
基础医学 | 505篇 |
口腔科学 | 74篇 |
临床医学 | 318篇 |
内科学 | 720篇 |
皮肤病学 | 191篇 |
神经病学 | 202篇 |
特种医学 | 94篇 |
外科学 | 419篇 |
综合类 | 14篇 |
预防医学 | 145篇 |
眼科学 | 77篇 |
药学 | 292篇 |
中国医学 | 8篇 |
肿瘤学 | 351篇 |
出版年
2024年 | 5篇 |
2023年 | 21篇 |
2022年 | 46篇 |
2021年 | 81篇 |
2020年 | 56篇 |
2019年 | 87篇 |
2018年 | 89篇 |
2017年 | 57篇 |
2016年 | 87篇 |
2015年 | 84篇 |
2014年 | 85篇 |
2013年 | 135篇 |
2012年 | 199篇 |
2011年 | 250篇 |
2010年 | 154篇 |
2009年 | 114篇 |
2008年 | 219篇 |
2007年 | 235篇 |
2006年 | 230篇 |
2005年 | 217篇 |
2004年 | 210篇 |
2003年 | 191篇 |
2002年 | 192篇 |
2001年 | 47篇 |
2000年 | 48篇 |
1999年 | 55篇 |
1998年 | 36篇 |
1997年 | 31篇 |
1996年 | 42篇 |
1995年 | 27篇 |
1994年 | 34篇 |
1993年 | 16篇 |
1992年 | 33篇 |
1991年 | 31篇 |
1990年 | 27篇 |
1989年 | 36篇 |
1988年 | 23篇 |
1987年 | 27篇 |
1986年 | 15篇 |
1985年 | 13篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1979年 | 7篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1975年 | 3篇 |
1972年 | 5篇 |
1970年 | 7篇 |
排序方式: 共有3660条查询结果,搜索用时 15 毫秒
991.
992.
Hibino S Shibuya M Hoffman MP Engbring JA Hossain R Mochizuki M Kudoh S Nomizu M Kleinman HK 《Cancer research》2005,65(22):10494-10501
Recently, we reported that the laminin alpha5 synthetic peptide A5G27 (RLVSYNGIIFFLK, residues 2,892-2,904) binds to the CD44 receptor of B16-F10 melanoma cells via the glycosaminoglycans on CD44 and inhibits tumor cell migration, invasion, and angiogenesis in a dominant-negative manner. Here, we have identified the potential mechanism of A5G27 activity using WiDr human colorectal carcinoma cells. WiDr cells bound to the laminin A5G27 peptide via the heparin-like and chondroitin sulfate B glycosaminoglycan side chains of CD44. Cell binding to fibroblast growth factor (FGF2) was blocked by laminin peptide A5G27 but not by either a scrambled version of this peptide or by another laminin peptide known to bind cell surface proteoglycans. FGF2 signaling involving tyrosine phosphorylation was also blocked by laminin peptide A5G27 but was not affected by peptide controls. Finally, we have shown that peptide A5G27 directly blocks FGF2 binding to heparin. Peptide A5G27 has sequence homology to a region on FGF2 that binds heparin and the FGF receptor and is important in FGF2 central cavity formation. We conclude that peptide A5G27 inhibits metastasis and angiogenesis by blocking FGF2 binding to the heparan sulfate side chains of CD44 variant 3, thus decreasing FGF2 bioactivity. 相似文献
993.
Hemodilution during cardiopulmonary bypass increases cerebral infarct volume after middle cerebral artery occlusion in rats 总被引:5,自引:0,他引:5
Homi HM Yang H Pearlstein RD Grocott HP 《Anesthesia and analgesia》2004,99(4):974-81, table of contents
Although the optimal hematocrit during cardiopulmonary bypass (CPB) is not defined, excessive hemodilution may lead to organ ischemia via a reduction in oxygen-carrying capacity uncompensated by autoregulatory and/or rheologic increases in organ blood flow. As a result, the consequences of hemodilution in patients at risk for cerebral ischemia are not clearly understood. We designed this study to evaluate the effects of hemodilution in the setting of focal cerebral ischemia during CPB. Wistar rats surgically prepared for CPB were randomized to either hemodilution (hemoglobin (Hb), 6 g/dL; n = 9) or control (Hb, 11 g/dL; n = 8) groups and subsequently exposed to focal cerebral ischemia induced by middle cerebral artery occlusion (MCAO). Immediately after the onset of MCAO (maintained for 90 min), 65 min of hypothermic (28 degrees C) CPB was initiated. Twenty-four hours later, functional neurological outcome and cerebral infarct volume were determined. Compared with controls, the hemodilution group had worse neurological performance (new score = 8 [2], hemodilution; versus 10 [2], control; P = 0.030) and larger total cerebral infarct volumes (182 +/- 84 mm(3), hemodilution; versus 103 +/- 58 mm(3), control; P = 0.043). In this experimental model of CPB with reversible MCAO-induced focal cerebral ischemia, hemodilution worsened neurological function and increased cerebral infarct volume. 相似文献
994.
Grocott HP Clark JA Homi HM Sharma A 《Seminars in cardiothoracic and vascular anesthesia》2004,8(3):213-226
Compared to the neurologic morbidity of stroke and cognitive dysfunction, "other" neurologic complications involving injuries to the brachial plexus, phrenic nerve, cranial nerves, other peripheral nerves, as well as the visual pathways, have been disproportionately underrepresented in the cardiac surgery and anesthesiology literature. These injuries are often missed in the early postoperative period when attention is focused principally on recovery from the acute trespass of cardiac surgery and cardiopulmonary bypass. However, when these problems do become apparent, they can cause considerable discomfort and morbidity. An overview of the current concepts of injury mechanisms/etiology, diagnosis, prognosis, and when possible, prevention of these injuries is presented. 相似文献
995.
We characterized the effects of vanadate, an inhibitor of tyrosine phosphatase, on the tension, the level of myosin light chain (MLC) phosphorylation, and Rho A activation in intact ileal longitudinal smooth muscle of the guinea pig to study the role of tyrosine phosphorylation in contraction signaling. Vanadate exerted a sustained contraction with a slow onset of tension development, in a concentration-dependent manner. The contractile effects of vanadate were accompanied by increases in the level of MLC phosphorylation. The tyrosine kinase inhibitor genistein; the MLC kinase inhibitor 1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML-9); and the Rho kinase inhibitor (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide dihydrochloride, monohydrate (Y-27632) inhibited the vanadate-induced contraction and MLC phosphorylation. Vanadate caused Rho A translocation from the cytosol to the membrane fraction, which was inhibited by genistein, but not by ML-9 and Y-27632. These data indicate that vanadate induces Rho A activation probably via protein tyrosine phosphorylation and the subsequent contraction through increases in the level of MLC phosphorylation. 相似文献
996.
Inactivation, one of the mechanisms of resistance to macrolide, lincosamide and streptogramin (MLS) antibiotics, appears to be fairly rare in clinical isolates in comparison with target site modification or efflux. However, inactivation is one of the major mechanisms through which macrolide-producing organisms avoid self-damage during antibiotic biosynthesis. The inactivation mechanisms for MLS antibiotics in pathogens are mainly hydrolysis, phosphorylation, glycosylation, reduction, deacylation, nucleotidylation, and acetylation. The ere (erythromycin resistance esterase) and mph (macrolide phosphotransferase) genes were originally found in Escherichia coli. Subsequently, Wondrack et al. (Wondrack, L.; Massa, M.; Yang, B.V.; Sutcliffe, J. Antimicrob. Agents Chemother., 1996, 40, 992) reported ere-like activity in Staphylococcus aureus. In addition, a variant of erythromycin esterase was found in Pseudomonas sp. from aquaculture sediment by Kim et al. (Kim, Y.H.; Cha, C.J.; Cerniglia, C.E. FEMS Microbiol. Lett., 2002, 210, 239). Although the mph genes, including mph(K), were first characterized in E. coli, a recent study revealed that S. aureus and Stenotrophomonas maltophilia have mph(C). The mph(C) has a low G+C content, like mph(B), and has high homology with mph(B), but not with mph(A) or mph(K). Consequently, the mph(C) and ere(B) genes seem to have originated from Gram-positive bacteria and been transferred between Gram-positive and Gram-negative bacteria. In this chapter, the genes and the mechanisms involved in the inactivation of MLS antibiotics by antibiotic-producing bacteria are reviewed. 相似文献
997.
Hair plucking is the most frequently used method of anagen induction within hair follicles. In this study, we found that plucking leads to the entire renewal of the follicular stem cell region of the mouse pelage follicle. Comparative histochemical analysis revealed that S100A4 protein was specifically distributed in the outer layer of the epithelial sac, which has been identified as the stem cell region of the pelage follicle, whereas the slow cycling cells that retained 5-bromo-2'-deoxyuridine label for 8 wk were located in the epithelial sac and also in the hair germ. Combined terminal deoxynucleotide transferase deoxyuridine triphosphate fluorescein nick end labeling method and immunohistochemistry revealed that positive cells were detected in the outer layer of the epithelial sac possessing both bromo-2'-deoxyuridine and S100A4 labels 4.5 h after plucking. No terminal deoxynucleotide transferase deoxyuridine triphosphate fluorescein nick end labeling signal, however, was observed in the hair germ. Serial inspection of the plucked follicle revealed that almost all regions of the epithelial sac became terminal deoxynucleotide transferase deoxyuridine triphosphate fluorescein nick end labeling positive 12 h after plucking. Terminal deoxynucleotide transferase deoxyuridine triphosphate fluorescein nick end labeling-positive cells ultimately degenerated without forming apoptotic bodies. Subsequently, the surviving label-retaining cells in the hair germ migrated upward to re-epithelialize the damaged portion. These results indicate that follicular stem cells in the epithelial sac underwent cell death after plucking. It is likely that the hair germ is responsible for the reconstruction of the stem cell region of the hair follicle. 相似文献
998.
Matrix metalloproteinases (MMPs) have been reported to be involved in various inflammatory disorders. Previous studies revealed that MMP-2 and MMP-9 might play important roles in the breakdown of the blood-brain barrier (BBB) in the central nervous system (CNS) of patients with HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP). N-Biphenyl sulfonyl-phenylalanine hydroxamic acid (BPHA) selectively inhibits MMP-2, -9 and -14, but not MMP-1, -3 and -7. In the present study, we examined whether or not the selective MMP inhibitor BPHA could inhibit the heightened migrating activity of CD4+ T cells in HAM/TSP patients. The migration assay using an invasion chamber showed that migration of CD4+ T cells in HAM/TSP patients was inhibited by 25 microM BPHA. In addition, the inhibitory ratio of migrating CD4+ lymphocytes was higher in HAM patients compared to normal controls. These results suggest that the selective MMP inhibitor BPHA has therapeutic potential for HAM/TSP. 相似文献
999.
Microbiological markers for prediction and assessment of treatment outcome following non-surgical periodontal therapy 总被引:3,自引:0,他引:3
BACKGROUND: Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Bacteroides forsythus are considered major putative periodontal pathogens. However, it remains unclear what combinations or what levels of these bacteria influence treatment outcome. The purpose of the present study was to establish useful pathogenic markers for prediction and assessment of treatment outcome following scaling and root planing (SRP). METHODS: A total of 1,149 sites in 104 chronic periodontitis patients were clinically examined at baseline. Three months after SRP, 606 sites in 56 of these patients were reexamined. Subgingival plaque samples taken from the examined sites at baseline and 3 months were analyzed for the detection and quantification of A. actinomycetemcomitans, P. gingivalis, and B. forsythus using a colorimetric polymerase chain reaction technique. RESULTS: At baseline, high levels and a combination of P. gingivalis and B. forsythus were frequently detected in diseased sites (74%). SRP reduced the levels and the coexistence of P. gingivalis and B. forsythus (from 75% to 43%). However, in treated sites where there was less reduction of probing depth (<2 mm), or where bleeding on probing (BOP) or suppuration was detected, residual coexistence of P. gingivalis and B. forsythus and a high level of P. gingivalis after SRP were significantly more frequent. Furthermore, SRP did not improve BOP at sites exhibiting initially high levels of A. actinomycetemcomitans. CONCLUSIONS: These results suggest that the combination of P. gingivalis and B. forsythus, as well as the level of P. gingivalis, is useful in assessing treatment outcome. Furthermore, the high level of A. actinomycetemcomitans before SRP is a possible valuable predictor of treatment outcome. 相似文献
1000.