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   455篇
  免费   42篇
  国内免费   17篇
耳鼻咽喉   3篇
儿科学   19篇
妇产科学   5篇
基础医学   42篇
口腔科学   44篇
临床医学   38篇
内科学   91篇
皮肤病学   16篇
神经病学   6篇
特种医学   94篇
外科学   52篇
综合类   27篇
预防医学   19篇
眼科学   7篇
药学   29篇
中国医学   1篇
肿瘤学   21篇
  2023年   4篇
  2022年   1篇
  2020年   4篇
  2018年   11篇
  2017年   8篇
  2016年   12篇
  2015年   9篇
  2014年   5篇
  2013年   12篇
  2012年   10篇
  2011年   15篇
  2010年   18篇
  2009年   28篇
  2008年   8篇
  2007年   29篇
  2006年   3篇
  2005年   6篇
  2004年   8篇
  2003年   5篇
  2002年   8篇
  2001年   4篇
  2000年   8篇
  1999年   6篇
  1998年   21篇
  1997年   37篇
  1996年   32篇
  1995年   18篇
  1994年   16篇
  1993年   18篇
  1992年   1篇
  1991年   8篇
  1990年   3篇
  1989年   17篇
  1988年   19篇
  1987年   11篇
  1986年   13篇
  1985年   13篇
  1984年   8篇
  1983年   11篇
  1982年   7篇
  1981年   10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
  1949年   2篇
排序方式: 共有514条查询结果,搜索用时 15 毫秒
121.
Bone marrow transplant recipients are at risk for acquiring hepatitis C infection from the donated marrow. Twelve patients who were hepatitis C virus (HCV) RNA-negative pretransplant received marrow from anti-HCV seropositive donors. HCV RNA was present in the sera of seven of these donors. After transplant, serial serum specimens were obtained from all marrow recipients for determination of HCV RNA and aminotransferase levels. All seven recipients of marrow from HCV RNA-positive donors were HCV RNA-positive after marrow infusion; none cleared virus from the serum. All five recipients of marrow from anti-HCV seropositive, HCV RNA-negative donors remained free of HCV RNA in serum up to day 100. Abnormal serum aminotransferases were common in both HCV RNA- negative and HCV RNA-positive marrow recipients. One HCV-infected recipient developed marked elevation in aminotransferases after immunosuppressive drugs were stopped. We conclude that the presence of HCV RNA in the serum of marrow donors is an accurate predictor of HCV infection in marrow recipients. The acute infection was subclinical in all patients. The long-term risk of chronic hepatitis C virus infection in these patients remains to be determined.  相似文献   
122.
Garrick  LM; Gniecko  K; Liu  Y; Cohan  DS; Grasso  JA; Garrick  MD 《Blood》1993,81(12):3414-3421
We have used succinylacetone (4,6-dioxoheptanoic acid), a specific inhibitor of delta-aminolevulinic acid dehydrase, to gain insight into the defect in iron metabolism in the Belgrade anemia. The Belgrade rat has an inherited microcytic, hypochromic anemia associated with poor iron uptake into developing erythroid cells. Succinylacetone inhibits heme synthesis, leading to nonheme iron accumulation in mitochondria and cytosol of normal reticulocytes. When succinylacetone is used to inhibit Belgrade heme synthesis, iron from diferric transferrin does not accumulate in the stromal fraction that contains mitochondria, nor does 59Fe accumulate in the nonheme cytosolic fraction. Hence, the defect in the Belgrade rat reticulocyte occurs in the endocytic vesicle or in a step subsequent to iron transit from the vesicle but before the nonheme cytosolic or mitochondrial iron fractions. Therefore, the mutation affects either the release of iron from transferrin or iron transport from the vesicle to the mitochondrion.  相似文献   
123.
Berliner  N; Ault  KA; Martin  P; Weinberg  DS 《Blood》1986,67(1):80-85
Previous studies have suggested that analysis of the distribution of surface immunoglobulin light chain isotypes by flow cytometry provides evidence for monoclonality of B cell tumors and may detect populations of circulating tumor cells in patients with lymphoproliferative disease. We have used simultaneous flow cytometry and DNA restriction enzyme analysis on 58 samples of tissue and blood to determine whether lymphocyte populations detected by "kappa/lambda" analysis are indeed monoclonal. In greater than 90% of cases, abnormalities detected by flow cytometry correlated with monoclonal rearrangements of immunoglobulin genes as detected by Southern blot analysis. By analyzing tissue and blood from the same patients, we have also demonstrated that monoclonal circulating cells detected by flow cytometry reflect peripheral circulating tumor cells, since DNA from these cells shows the same immunoglobulin rearrangement as DNA from the original tumors in these patients. Although mixing studies suggested that DNA rearrangement studies were more sensitive than was flow cytometry in detecting minor populations of monoclonal lymphocytes, we found only one case in which this affected the diagnostic accuracy of the kappa/lambda analysis, with one notable exception, that of detection of a monoclonal proliferation of B cells that did not express surface immunoglobulin. The kappa/lambda test thus offers a powerful diagnostic tool in the evaluation of lymphoproliferative disease.  相似文献   
124.
Blood smears stained with Wright-Giemsa were obtained from 124 patients with pathologically confirmed cutaneous T cell lymphoma (CTCL), 70 patients with various other cutaneous disorders, and ten healthy adult volunteers. These were examined in a blinded fashion for atypical lymphocytes with cerebriform nuclei (CLs), which were characterized further according to cell diameter. CLs, comprising up to 15% of lymphocytes in smears, were observed in 20% of the patients with benign dermatitis. CLs, comprising up to 89% of lymphocytes in smears, were found in 22%, 30%, 50%, and 96% of patients with patch, plaque, tumor, and erythrodermic CTCL, respectively. Large-diameter CLs (15 to 20 micron) were observed only in smears from patients with CTCL. Total CL counts above 15 per 100 lymphocytes and/or the presence of large CLs occurred in 33 of 49 (67%) patients with erythrodermic disease and in only two patients with other skin manifestations. Blood smears obtained at the time of cytogenetic studies indicated that a total CL count above 15% was the smear criterion that correlated best with the demonstration of a chromosomally abnormal malignant clone in the blood. The presence of large CLs per se, although also predictive of a malignant clone, was less useful. Multivariate survival analysis showed that the duration of disease before the blood smear and the proportion of large CLs within the total CL population were the covariates that correlated most significantly with survival. We speculate that the reduced survival of patients with increased proportions of large CLs in smears reflects the presence of polyploid malignant lymphocytes in the blood.  相似文献   
125.
Mendelson  DS; Metz  EN; Sagone  AL Jr 《Blood》1977,50(6):1023-1030
The role of reduced glutathione in relation to hexose monophosphate shunt activity and peroxide detoxification has been well established in human erythrocytes. Less is known about the content of reduced glutathione in phagocytic leukocytes and the changes that occur during functional activity. We have measured the reduced sulfhydryl content of normal resting human granulocytes and of cells isolated from a patient with chronic granulomatous disease. Normal cells and those from the patient with chronic granulomatous disease contained similar concentrations of reduced sulfhydryls. Stimulation of a phagocytic response by incubation with opsonized zymosan particles resulted in prompt and nearly complete depletion of intracellular glutathione from normal granulocytes. This fall in reduced glutathione concentration was dependent on the phagocytic load. Exposure of chronic granulomatous disease granulocytes to a similar phagocytic load resulted in a slower and less complete fall in reduced glutathione. In normal cells, those from the chronic granulomatous disease patient, and those from an obligate carrier of the disease, the decrement in reduced glutathione during phagocytosis was correlated with oxidation of 14C-1-glucose and 14C-formate, nitroblue tetrazolium reduction, and the chemiluminescence phenomenon.  相似文献   
126.
Zander  AR; Verma  DS; Spitzer  G; Huynh  L; Johnston  D; Beran  M; Dicke  KA 《Blood》1980,56(6):1132-1135
Recovery of bone marrow cellularity, CFU-C, and CFU-S were studied sequentially over 90 days time after syngeneic bone marrow transplantation in mice. A minimal cell dose of 2 X 10(5) bone marrow cells was given. At day 28 after transplantation, CFU-C reached more than 50% of the normal range whereas the CFU-S concentration was less than 15%. Normalization of CFU-S occurred at day 90. The effect of the addition of peripheral blood nucleated cells on bone marrow hemopoietic recovery was studied at day 28. The augmentation of CFU-C and CFU-S recoverey were dose dependent. Optimal enhancement was seen with bone marrow to blood ratios of 1:1 and 1:2.5. This enhancement effect was lost when nucleated blood cells in a ratio of 1:10 were administered.  相似文献   
127.
Eight-five consecutive patients with relapsed or refractory Hodgkin's disease (HD) underwent high-dose chemotherapy or chemo/radiotherapy followed by autologous bone marrow (ABMT) and/or peripheral blood stem cell (PBSC) transplantation. Two preparative regimens were used. Twenty- two patients (26%) without prior radiation received fractionated total body irradiation (FTBI) 1,200 Gy in combination with high-dose etoposide (VP-16) 60 mg/kg and cyclophosphamide (CTX) 100 mg/kg. Sixty- three patients (74%) with prior radiotherapy received carmustine (BCNU) 450 mg/m2 instead of FTBI. The median age was 32 years (range, 16 to 56). The median number of prior chemotherapy regimens was three (range, 1 to 7). Forty-three patients (51%) received transplants in first relapse or second complete remission (CR), whereas 33 (39%) received transplants after second or subsequent relapse. All relapsed patients, except one, received conventional salvage chemotherapy and/or radiotherapy in an attempt to reduce tumor bulk before transplant. At the time of analysis in April 1994, fifty-seven patients (67%) are alive, including 44 (52%) in continuous CR, with a median follow-up for the surviving patients of 28 months (range, 7 to 66). Thirty patients (35%) relapsed at a median of 9 months (range, 1 to 43). Eleven patients (13%) died of transplant-related complications including veno- occlusive disease of the liver (VOD) in five, acute and late interstitial pneumonitis in three, graft failure in one, cerebral hemorrhage in one, and therapy-induced myelodysplasia (MDS)/acute leukemia in one patient. At a median follow-up of 25 months (range, 0.6 to 66), the cumulative probability of 2-year overall and disease-free survival (DFS) of all 85 patients is 75% (95% confidence interval [CI] 64% to 84%) and 58% (95% CI 47% to 69%), respectively. Three independent prognostic variables were identified by univariate analysis: number of prior chemotherapy regimens, prior radiotherapy, and extranodal disease at ABMT. Multivariate stepwise Cox regression identified the number of prior chemotherapy regimens as the only significant prognostic factor predicting for both relapse and DFS. There were no significant differences in the outcome of the treatment between the two preparative regimens. Our results confirm that high- dose therapy and ABMT is an effective therapy for patients with relapsed or refractory HD. Earlier transplantation is recommended before the development of drug resistance and end organ damage that results from repeated attempts of salvage therapy.  相似文献   
128.
129.
【目的】分析中国母亲母乳中性寡糖在哺乳期的浓度变化与母亲Lewis/Sec基因型的关系。【方法】收集51位中国母亲产后2,4,13周母乳,用高效液相色谱分析技术量化计算寡糖浓度。【结果】产后13周内母乳中性寡糖的总量虽然稳定,但是其中主要的三种成分浓度变化明显。3-FL浓度持续上升,分别由2周的84.6 mg/L增至13周的485.8 mg/L(P<0.05),2'-FL的浓度也呈上升趋势,由579.6 mg/L增至787.8 mg/L,LNF-1浓度则持续下降由596.9 mg/L降至304.5 mg/L。根据母乳中性寡糖的分类,29位母亲属于Le(a-,b+)型,10位母亲属于Le(a-,b-)型,12位母亲属于Le(a+,b-)型。【结论】中国母亲中性寡糖浓度变化有特异性;根据母乳分类确定的母亲Lewis基因型在研究人群中的分布与Lewis基因型在中国人群分布相似。  相似文献   
130.
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