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   10812篇
  免费   841篇
  国内免费   106篇
耳鼻咽喉   66篇
儿科学   513篇
妇产科学   316篇
基础医学   1504篇
口腔科学   209篇
临床医学   1077篇
内科学   2548篇
皮肤病学   156篇
神经病学   728篇
特种医学   430篇
外科学   1401篇
综合类   195篇
一般理论   10篇
预防医学   678篇
眼科学   266篇
药学   689篇
中国医学   98篇
肿瘤学   875篇
  2023年   59篇
  2022年   113篇
  2021年   229篇
  2020年   128篇
  2019年   236篇
  2018年   259篇
  2017年   198篇
  2016年   202篇
  2015年   261篇
  2014年   319篇
  2013年   431篇
  2012年   669篇
  2011年   676篇
  2010年   398篇
  2009年   366篇
  2008年   634篇
  2007年   611篇
  2006年   629篇
  2005年   586篇
  2004年   530篇
  2003年   452篇
  2002年   415篇
  2001年   398篇
  2000年   396篇
  1999年   324篇
  1998年   140篇
  1997年   117篇
  1996年   113篇
  1995年   105篇
  1994年   77篇
  1993年   102篇
  1992年   183篇
  1991年   156篇
  1990年   153篇
  1989年   161篇
  1988年   145篇
  1987年   130篇
  1986年   127篇
  1985年   106篇
  1984年   66篇
  1983年   48篇
  1982年   43篇
  1981年   44篇
  1980年   31篇
  1979年   35篇
  1978年   22篇
  1977年   26篇
  1976年   26篇
  1975年   15篇
  1974年   14篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
Interleukin-5 has a specific role in various eosinophilic activities. It is the predominant cytokine produces by activated T-lymphocytes isolated from patients with idiopathic hypereosinophilic syndrome. We studied a young patient suffering from idiopathic hypereosinophilic syndrome who presented with Horner's syndrome, peripheral neuropathy and skin ulcers. The IL-5 gene expression by CD4+ T-lymphocytes and the peripheral eosinophil count were raised. The skin ulcers continued to deteriorate despite a swift reduction of the IL-5 gene expression and peripheral eosinophil count following systemic corticosteroid treatment. We suggest that peripheral eosinophilia may not be responsible for the damage in skin lesions and more aggressive treatment may be required.  相似文献   
53.
Lamivudine treatment in patients with chronic hepatitis B virus (HBV) infection may improve clinical state and suppress viral replication before liver transplantation. Emergence of lamivudine-resistant YMDD mutant is common. We report the results of liver transplantation in 16 patients with pretransplantation YMDD mutants after receiving lamivudine treatment for a median of 738 days (range, 400-1799 days). Adefovir dipivoxil (10 mg daily) was added on to lamivudine for a median of 20 days (range, 8-271 days) before (n = 11) or at (n = 5) liver transplantation, and the combination was continued indefinitely thereafter. Eight patients received additional intravenous hepatitis B immune globulin (HBIG) for a median of 24 months. Fifteen patients with known pre-adefovir HBV DNA levels had a median titer of 14,200 x 10(3) copies/mL (2 x 10(3) to 4,690,000 x 10(3) copies/mL), and 14 had HBV DNA >10(5) copies/mL. All but 1 patient remained positive for HBV DNA (by quantitative polymerase chain reaction [qPCR]) at the time of liver transplantation, and the titer was greater than10(5) copies/mL in 8 patients. The median follow-up after liver transplantation was 21.1 (range, 4.4-68.9) months. One patient (6%) died of an unrelated cause 12.2 months after transplantation, and 15 patients (94%) were alive with the original graft. All patients cleared HBV DNA and had no detectable HBV DNA by qPCR at the latest follow-up. Fourteen patients had cleared hepatitis B surface antigen (HBsAg), but 2 patients who received only adefovir dipivoxil and lamivudine without HBIG remained HBsAg positive after 7.7 and 9.5 months. Serum HBV DNA, however, was negative, and there was no biochemical or histological evidence of recurrence. Adefovir dipivoxil was well tolerated with no significant renal toxicity. In conclusion, a combination of add-on adefovir dipivoxil plus lamivudine therapy provides effective prophylaxis in patients with pretransplantation YMDD mutant that may be actively replicating. The cost effectiveness of additional passive immunoprophylaxis remains to be defined.  相似文献   
54.
There are few reports of positron emission tomography (PET) in juvenile parkinsonism (JP). We report on the results of (18)F-6-fluoro-L-dopa (FD) PET in a 14-year-old patient with JP of 5 years duration associated with atypical features. This is the youngest subject to be investigated to date. There was a severe asymmetric reduction in striatal FD uptake, with a rostrocaudal gradient in the putamen similar to that seen in adult-onset idiopathic parkinsonism. Extensive DNA analysis in this patient did not show mutations in the parkin gene.  相似文献   
55.
OBJECTIVE: To analyze treatment and survival of a large cohort of patients with retroperitoneal soft-tissue sarcomas (STS) treated and prospectively followed at a single institution. SUMMARY BACKGROUND DATA: Retroperitoneal STS are relatively uncommon and constitute a difficult management problem. Although surgical resection is often difficult or impossible, current chemotherapy is not effective and radiation is limited by toxicity to adjacent structures. Thus, complete surgical resection remains the most effective modality for selected primary and recurrent disease. METHODS: Five hundred patients with retroperitoneal STS were admitted and treated between July 1, 1982, and September 30, 1997, and prospectively followed. Patient, tumor, and treatment variables were analyzed for disease-specific and disease-free survival. Survival was determined with the Kaplan-Meier method. Statistical significance was evaluated using the logrank test for univariate influence and Cox model stepwise regression for multivariate influence. RESULTS: Two hundred seventy-eight patients (56%) had primary disease and 222 (44%) recurrent disease. Median follow-up was 28 months (range 1 to 172 months), 40 months for survivors. Median survival was 72 months for patients with primary disease, 28 months for those with local recurrence, and 10 months for those with metastasis. For patients with primary or locally recurrent tumors, unresectable disease, incomplete resection, and high-grade tumors significantly reduced survival time. CONCLUSIONS: In this study of patients with retroperitoneal STS, stage at presentation, high histologic grade, unresectable primary tumor, and positive gross margin are strongly associated with the tumor mortality rate. Patients approached with curative intent should undergo aggressive attempts at complete surgical resection. Incomplete resection should be undertaken only for symptom relief.  相似文献   
56.
We describe a radial partition enzyme immunoassay in which fully automated quantification of human thyrotropin (hTSH) takes less than 11 min. This "sandwich"-type assay involves two monoclonal antibodies, both specific for the intact hTSH molecule. The solid phase consists of tabs of glass-fiber filter paper containing a pre-immobilized monoclonal anti-hTSH antibody complexed with a goat antibody specific for the Fc region of mouse IgG. The patient's sample is first applied to the central "reaction zone" of the tab, wherein hTSH binds to the immobilized antibody. Application of a buffered solution containing enzyme-labeled Fab' fragments of the second monoclonal anti-hTSH antibody initiates "sandwich" formation. A wash buffer containing a fluorogenic substrate elutes unbound conjugate to the tab periphery. The bound enzyme conjugate is quantified by measuring the rate of increase in fluorescence in the reaction zone of the tab, then converting the rate to clinical units by comparison with a stored calibration curve. The clinical utility and performance of the present assay compare favorably with those of other sensitive assays for hTSH.  相似文献   
57.
Mucosal hemodynamics (by reflectance spectrophotometry) and mucosal damage (by histologic examination) following acute colonic ischemia were evaluated in different anatomic locations in the colon of anesthetized rats. The reflectance spectrophotometer provides an index of mucosal hemoglobin concentration (IHB) and an index of oxygen saturation of hemoglobin (ISO2). The patterns of ischemia without congestion (IHB, ISO2) during superior mesenteric artery occlusion, and ischemia with congestion (IHB, ISO2) during portal vein occlusion, previously demonstrated in the stomach and duodenum, are also applicable to the colon. The significant linear correlations between changes (as percent of baseline) in IHB, ISO2, and hydrogen gas clearance suggest that changes in these indices are adequate indicators of changes in colonic mucosal perfusion. Superior mesenteric artery ligation produced significant reductions in both indices, and an increase in damage in the mucosa of the cecum, transverse colon, splenic flexure, and left colon, but not the rectum. Inferior mesenteric artery ligation produced only slight reduction in these indices and minimal damage only in the mucosa of the splenic flexure. These results support the hypothesis that the superior mesenteric artery is more important than the inferior mesenteric artery in maintaining colonic perfusion and colonic mucosal integrity in the rat.Supported by the American Society for Gastrointestinal Endoscopy Career Development Award (H850208, H870212), Veterans Administration Medical Research Funds; and in part by research grants (0162-01, 0162-02; 0291-01) from the Smokeless Tobacco Research Council, Inc.; and by funds provided by the Cigarette and Tobacco Surtax Fund of the State of California through the Tobacco Related Disease Research Program of the University of California.  相似文献   
58.
P C Leung 《Microsurgery》1989,10(3):242-244
This study reports the results of 30 patients who entered a program of sensory reeducation following toe-to-thumb transfer. Results were analyzed after subdividing the patients into those whose injury had produced severe scarring (fibrotic group, N = 15) and those with clean, more distal amputations (non-fibrotic group, N = 15). Patients who were unable to complete sensory reeducation were considered as "drop-out" controls. Although the follow-up time was less than 1 year, the group receiving sensory reeducation did improve to a greater degree and more quickly than the controls, with the level of two-point discrimination recovered being better than that originally present in the toe.  相似文献   
59.
Three monoclonal antibodies (MoAbs L49-15, L81-11 and L238-14) were raised against recombinant human lymphotoxin (rLT) derived from E. coli containing the cDNA sequence specifying LT. MoAb L81-11 strongly neutralised the cytotoxicity of LT derived either from E. coli or the RPMI 1788 lymphoblastoid cell line, whilst the other two MoAbs were only weakly neutralising in this respect. L81-11 and L238-14 MoAbs bound to different antigenic determinants on the rLT molecule, but neither bound to other lymphokines such as the structurally related tumour necrosis factor (TNF). As such, these MoAbs were ideal reagents for immunoassay of LT and a very sensitive, highly specific immunoradiometric assay (IRMA) was developed. This assay was rapid to perform and was capable of detecting as little as 10 pg/ml of LT. Application of the LT IRMA in combination with previously developed human gamma-interferon (IFN-gamma) and human TNF-specific IRMA (Crane et al., 1985; Meager et al., 1987) permitted independent estimations of these three substances to be carried out in parallel. By these means, it was found that RPMI 1788 produced both LT and TNF, but not IFN-gamma. Extensive analyses on cytokine (monokine and lymphokine) preparations derived from a variety of activated lymphocytes are also reported. Co-production of LT, TNF and IFN-gamma was a common finding, even occurring in alloantigen-specific T helper cell clones.  相似文献   
60.
The biomechanical properties and histocompatibility of a glutaraldehyde-treated xenograft were examined after implanting it in 27 rabbits. This xenograft was used as an Achilles tendon substitute placed in vivo for 2 to 48 wk. The specimens were then subjected to mechanical strength testing using a specially constructed tensioning device. The contralateral Achilles tendon was used as the reference baseline. Mechanical testing showed that the strength of the implanted graft increased to 33.5% of the normal side at week 10 and to 79.5% at week 14. The host generated a fibrous cord around the xenograft, linking the two ends of the Achilles tendon. Light and electron microscopic examination showed fibroblastic infiltration of varying magnitude in all specimens but no statistical correlation between degree of infiltration and duration of implantation was found. Also, there was no histological evidence of immunological rejection within the 48 wk of study.  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