首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1006篇
  免费   52篇
  国内免费   6篇
耳鼻咽喉   3篇
儿科学   20篇
妇产科学   7篇
基础医学   113篇
口腔科学   6篇
临床医学   65篇
内科学   256篇
皮肤病学   12篇
神经病学   70篇
特种医学   20篇
外科学   180篇
综合类   4篇
预防医学   48篇
眼科学   1篇
药学   50篇
中国医学   2篇
肿瘤学   207篇
  2024年   1篇
  2023年   9篇
  2022年   25篇
  2021年   48篇
  2020年   12篇
  2019年   21篇
  2018年   21篇
  2017年   22篇
  2016年   40篇
  2015年   24篇
  2014年   40篇
  2013年   43篇
  2012年   85篇
  2011年   92篇
  2010年   41篇
  2009年   37篇
  2008年   57篇
  2007年   71篇
  2006年   53篇
  2005年   58篇
  2004年   62篇
  2003年   60篇
  2002年   52篇
  2001年   4篇
  1999年   6篇
  1998年   10篇
  1997年   1篇
  1996年   8篇
  1995年   11篇
  1994年   11篇
  1993年   4篇
  1992年   5篇
  1991年   5篇
  1990年   7篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1983年   1篇
  1981年   3篇
  1980年   1篇
  1979年   2篇
  1976年   1篇
  1975年   2篇
  1972年   1篇
  1968年   1篇
  1967年   1篇
  1966年   1篇
排序方式: 共有1064条查询结果,搜索用时 31 毫秒
61.
The radioactive and thermal effects of radon hot spring were biochemically compared under a sauna room or hot spring conditions with a similar chemical component, using the parameters that are closely involved in the clinic for radon therapy. The results showed that the radon and thermal therapy enhanced the antioxidation functions, such as the activities of superoxide dismutase (SOD) and catalase, which inhibit lipid peroxidation and total cholesterol produced in the body. Moreover the therapy enhanced concanavalin A (ConA)-induced mitogen response and increased the percentage of CD4 positive cells, which is the marker of helper T cells, and decreased the percentage of CD8 positive cells, which is the common marker of killer T cells and suppressor T cells, in the white blood cell differentiation antigen (CD8/CD4) assay. Furthermore, the therapy increased the levels of alpha atrial natriuretic polypeptide (alpha ANP), beta endorphin, adrenocorticotropic hormone (ACTH), insulin and glucose-6-phosphate dehydrogenase (G-6-PDH), and it decreased the vasopression level. The results were on the whole larger in the radon group than in the thermal group. The findings suggest that radon therapy contributes more to the prevention of life-style-related diseases related to peroxidation reactions and immune suppression than to thermal therapy. Moreover, these indicate what may be a part of the mechanism for the alleviation of hypertension, osteoarthritis (pain), and diabetes mellitus brought about more by radon therapy than by thermal therapy.  相似文献   
62.
We conducted a phase II study of combination chemotherapy with nedaplatin (NP) with irinotecan (CPT) to determine the effects against unresectable non-small cell lung cancer (NSCLC) and to determine the qualitative and quantitative toxicities of this combination chemotherapy in 70 years or older patients. Thirty-eight patients received 100 mg/m2 NP on day 1 and 60 mg/m2 CPT on days 1 and 8 every four weeks. Twenty-five patients achieved PR, nine SD and three PD, and the overall response rate was 65.8%. Nineteen patients (50%) experienced grade 4 neutropenia. Neutropenic fever occurred in 11 patients (29%) and one of them died. Of other grade 3 non-hematologic toxicities, two patients experienced diarrhea; one interstitial pneumonitis; one liver injury; and one rash. The median survival time was 418 days and the one-year survival rate was 55.3%. In conclusion, NP combined with CPT is an active treatment for elderly patients with NSCLC.  相似文献   
63.
UFT is an oral 5-fluorouracil derivative drug that may improve postoperative survival in non-small cell lung cancer (NSCLC), and experimental studies have shown that UFT inhibits tumor angiogenesis. In the present study, therefore, the correlation between tumor angiogenesis (intratumoral microvessel density, IMVD) and the efficacy of UFT in 162 patients with pathologic stage I NSCLC was examined. For higher IMVD tumors (IMVD > or = 20, n = 80), the 5-year survival rate of UFT-treated patients (82.5%) was significantly higher than that of surgery-alone patients (61.8%, P = 0.032). For lower IMVD tumors (n = 82), however, there was no difference in the survival between these groups (5-year survival rates, 84.9% and 82.6%, respectively; P = 0.657). Multivariate analyses confirmed that postoperative UFT administration was effective for higher IMVD tumors (P = 0.046; relative risk [RR] and the 95% confidence interval [CI], 0.288 [0.084-0.979]), but not for lower IMVD tumors (P = 0.616; 0.726 [0.208-2.539]). Moreover, vascular endothelial growth factor (VEGF) status was also a predictive factor. For tumor showing strong VEGF expression (n = 63), UFT administration improved the survival (5-year survival rates of UFT-treated patients and surgery-alone patients, 84.6% and 60.0%, respectively; P = 0.048); for weakly VEGF-expressing tumors (n = 99), UFT administration did not influence the survival (5-year survival rates, 83.4% and 79.1%, respectively; P = 0.455). Multivariate analyses demonstrated that UFT administration seemed to be effective for strong VEGF tumors (P = 0.063; RR and the 95% CI, 0.234 [0.051-10.81]), but not for weak VEGF tumors (P = 0.456; 0.673 [0.293-1.900]). In conclusion, the efficacy of postoperative UFT administration in NSCLC was correlated with tumor angiogenesis.  相似文献   
64.
We compared preoperative evaluations of 93 fine-needle aspiration biopsies (FNAB) of major salivary gland tumors done over a 5 year period with pathologic diagnoses of surgically resected specimens. The overall accuracy was 88.5%. Eight of 15 aspirates from malignant tumors were correctly diagnosed by FNAB, for a sensitivity of 53.3%, while 69 of 72 aspirates from benign tumors were correctly diagnosed by FNAB, for a specificity of 95.8%. Five malignant tumors diagnosed as benign by FNAB were squamous cell carcinoma, carcinoma in pleiomorphic adenoma, malignant lymphoma, low-grade mucoepidermoid carcinoma, and acinic cell carcinoma. The false negatives in the first 2 cases appeared to be due to inaccurate placement of the aspiration site. The other 3 cases showed lack of atypia, leading to a benign diagnosis. Malignant lymphoma is difficult to diagnose as malignant, even in properly aspirated specimens, so we recommend open biopsy when malignant lymphoma is suspected from physical and radiological examinations. A case confirmed pathologically as benign myoepithelioma was diagnosed as adenoid cystic carcinoma preoperatively, based on the finding of a cribriform pattern containing mucin. It should be borne in mind that myoepithelioma and adenoid cystic carcinoma are difficult to distinguish by FNAB. Although FNAB is useful in diagnosing major salivary gland tumors, its low sensitivity (high percentage of false negatives) is undesirable. It may thus be helpful in intraoperative decision-making when combined with frozen sectioning.  相似文献   
65.
Matsuyama S  Taguchi F 《Virology》2002,295(1):160-171
The soluble receptor-resistant (srr) mutants, srr7 and srr11, isolated from a murine coronavirus, mouse hepatitis virus (MHV) JHMV, have an amino acid mutation at positions 1114 (Leu to Phe) and 65 (Leu to His), respectively, in the spike (S) protein. These mutants failed to efficiently infect BHK cells expressing CEACAM1b (BHK-R2), due to their low entry into this cell line, although they infected cells expressing CEACAM1a (BHK-R1) in a manner similar to that of wild-type (wt) JHMV cl-2 (Matsuyama and Taguchi, Virology 273, 80-89, 2000). Following the repeated passage of these mutants through BHK-R2 cells, viruses were no longer isolated from srr11-infected cells, while two distinct mutants, srr7A and srr7B, were obtained from srr7-infected cells. Srr7A and srr7B grew 2 log10 higher than srr7 and induced fusion in BHK-R2 cells, being similar to wt virus. In addition to the amino acid change at position 1114 that stemmed from parental srr7, srr7A and srr7B had mutations around position 280, corresponding to the third region of the S1N330 receptor-binding site (S1N330-III) common to all MHV strains examined thus far. Srr7A and srr7B S proteins showed high fusogenicity in both BHK-R1 and BHK-R2 cells, like the wt virus, while srr7Aa and srr7Ba S proteins, which had mutations in S1N330-III but not at amino acid 1114, exhibited profoundly reduced fusion activity in these cell lines. These findings suggest that communication between S1N330-III and the amino acid at position 1114 is important for efficient fusion activity in BHK-R2 cells. S1N330-III is a possible region in the S1 involved in viral entry into cells.  相似文献   
66.
We present a case exhibiting persistent joint effusion and formation of a gigantic popliteal synovial cyst 8 years after total knee joint arthroplasty. Assessment using flow cytometry revealed that both joint and cyst fluid contained abundant macrophage-phagocytosing wear particles. This finding indicates that wear particles participated in formation of the cyst through the communication between the joint cavity and cyst. Intraoperatively, prominent villous synovial proliferation was observed in both the joint and cyst, and delamination failure of the polyethylene insert was identified. Because no evidence of prosthetic loosening was found, only polyethylene insert revision and synovectomy were undertaken, resulting in a successful outcome. This case suggests that synovial cyst formation in popliteal lesions might represent a sign of wear-particle generation after total knee joint arthroplasty.  相似文献   
67.
There are various forms of renal lesions in patients with human immunodeficiency virus(HIV), however reported cases of immune-complex glomerulonephritis are scarce. Here we describe an HIV-positive patient with Henoch-Sch?nlein purpura nephritis(HSPN), which presented as nephrotic syndrome. In addition to therapy combined with glucocorticosteroid and inhibition of the renin-angiotesin system(RAS), plasmapheresis and antiretroviral therapy produced a favorable outcome. A 26-year-old HIV positive man was admitted for purpura on both lower limbs. Despite glucocorticosteroid treatment, purpura recurred and urinary protein increased to 5-10 g daily. HSPN was diagnosed based on the skin and renal biopsies. During 2 months of treatment with combined glucocorticosteroid and RAS inhibition, nephrotic syndrome persisted. He received double filtration plasmapheresis(DFPP). Soon after, urine protein decreased to 2-3 g daily and macrohematuria decreased. The second renal biopsy showed a decrease in IgA deposition and improvement of acute inflammatory changes. In addition, highly active antiretroviral therapy was started to reduce the high viral load. After 3 weeks, HIV-1-RNA rapidly decreased and urine protein decreased to 1 g daily. After a year, urinary protein was negative, but mild microhematuria persisted. We speculate that the refractory nephrotic syndrome in this patient might be associated with the abnormal immunological condition due to HIV infection.  相似文献   
68.
The purpose of the present study was to assess the effects of chronic treatment with an orally active chymase inhibitor, 4-[1-(naphthylmethyl)benzimidazol-2-ylthio]butanoic acid (TEI-E548), in a hamster myocardial infarction model. In the first experiment, after confirming the biochemical inhibitory action of TEI-E548 on human and hamster chymases (Ki = 6.2 and 30.6 nM, respectively), the biological action of TEI-E548 in vivo was assessed by the inhibition of hamster chymase-induced microvascular leakage. In the second experiment, myocardial infarction was produced by coronary artery ligation in male Syrian hamsters. TEI-E548 (0.1% containing chow) was given 24 h after surgery and continued for 3 or 5 weeks, while the control and sham-operated groups were fed a standard chow. The survival rate was assessed in each group. At the end of each study period, blood pressure was measured at the left hind-limb, the heart rate and cardiac function were measured by echocardiography, the end-diastolic pressure by a direct catheterization, and organ weights and biochemical parameters, including plasma renin and angiotensin-converting enzyme activities and plasma angiotensin I and angiotensin II concentrations, were measured. In the first experiment, a standard chow containing 0.1% TEI-E548 completely inhibited the hamster chymase-induced microvascular leakage. In the second experiment, TEI-E548 treatment significantly increased the survival rate (37% versus control), and attenuated cardiac hypertrophy (13% versus control) and end-diastolic left ventricular pressure (34% versus control), but it did not decrease the infarction size nor improve the ejection fraction. The plasma angiotensin II concentration post-myocardial infarction was significantly suppressed by TEI-E548 throughout the study period. We conclude that TEI-E548 is an orally active useful chymase inhibitor and improves survival and cardiac hypertrophy of the post-myocardial infarction hamster.  相似文献   
69.
The melanoma differentiation-associated gene 7 (mda-7), also called interleukin (IL)-24, suppresses the growth of some cancers in vitro and in vivo as a result of the ectopic expression of its protein. However, the function of the secreted form of the protein in cancer has not been previously studied. The purpose of this study was to determine the antiangiogenic function of a secreted form of the MDA-7/IL-24 protein (sMDA-7/IL-24). In vitro, sMDA-7/IL-24 inhibited both endothelial cell differentiation and migration of endothelial cells induced by vascular endothelial growth factor and basic fibroblast growth factor. The sMDA-7/IL-24-mediated inhibitory effect was 10-50 times more potent than endostatin, IFN-gamma, and IFN-inducible protein 10 in vitro. Furthermore, the inhibitory effect was not mediated by IFN or IFN-inducible protein 10. IL-22 receptor mediated the antiangiogenic activity of sMDA-7/IL-24. Administration of a blocking antibody to IL-22 receptor in conjunction with sMDA-7/IL-24 led to abrogation of inhibition of endothelial differentiation. sMDA-7/IL-24 inhibited vascular endothelial growth factor-induced angiogenesis as evidenced by reduced vascularization and hemoglobin content in in vivo Matrigel plug assays. In vivo, the growth of human lung tumor cells was significantly inhibited, and vascularization was reduced when the cells were mixed with 293 cells stably expressing sMDA-7/IL-24. Systemic administration of sMDA-7/IL-24 inhibited lung tumor growth in a mouse xenograft model. Associated with tumor growth inhibition was decreased tumor microvessel density and hemoglobin content, indicating the presence of antiangiogenic activity. These data demonstrate that sMDA-7/IL-24 is a novel and potent antiangiogenic effector and support the development of MDA-7/IL-24-based therapeutics.  相似文献   
70.
In many common cancers such as transitional cell carcinoma (TCC), specific genes are hypermethylated, whereas overall DNA methylation is diminished. Genome-wide DNA hypomethylation mostly affects repetitive sequences such as LINE-1 retrotransposons. Methylation of these sequences depends on adequate expression of DNA methyltransferase I (DNMT1) during DNA replication. Therefore, DNMT1 expression relative to proliferation was investigated in TCC cell lines and tissue as well as in renal carcinoma (RCC) cell lines, which also display hypomethylation, as indicated by decreased LINE-1 methylation. Cultured normal uroepithelial cells or normal bladder tissue served as controls. In all tumor cell lines, DNMT1 mRNA as well as protein was decreased relative to the DNA replication factor PCNA, and DNA hypomethylation was present. However, the extents of hypomethylation and DNMT1 downregulation did not correlate. Reporter gene assays showed that the differences in DNMT1 expression between normal and tumor cells were not established at the level of DNMT1 promoter regulation. Diminished DNMT1:PCNA mRNA ratios were also found in 28/45 TCC tissues but did not correlate with the extent of DNA hypomethylation. In addition, expression of the presumed de novo methyltransferases DNMT3A and DNMT3B mRNAs was investigated. DNMT3B overexpression was observed in about half of all high-stage TCC (DNMT3B vs. tumor stage, chi(2): p = 0.03), whereas overexpression of DNMT3A was rarer and less pronounced. Expression of DNMT3A and DNMT3B in most RCC lines was higher than in TCC lines. Our data indicate that DNMT1 expression does not increase adequately with cell proliferation in bladder cancer. This relative downregulation probably contributes to hypomethylation of repetitive DNA but does not determine its extent alone.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号