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   723篇
  免费   53篇
  国内免费   2篇
耳鼻咽喉   9篇
儿科学   15篇
妇产科学   7篇
基础医学   121篇
口腔科学   20篇
临床医学   35篇
内科学   172篇
神经病学   79篇
特种医学   98篇
外科学   60篇
综合类   3篇
预防医学   8篇
眼科学   9篇
药学   41篇
肿瘤学   101篇
  2023年   3篇
  2022年   7篇
  2021年   12篇
  2020年   11篇
  2019年   16篇
  2018年   9篇
  2017年   19篇
  2016年   20篇
  2015年   16篇
  2014年   25篇
  2013年   24篇
  2012年   54篇
  2011年   45篇
  2010年   26篇
  2009年   36篇
  2008年   28篇
  2007年   43篇
  2006年   43篇
  2005年   44篇
  2004年   37篇
  2003年   49篇
  2002年   36篇
  2001年   10篇
  2000年   6篇
  1999年   16篇
  1998年   18篇
  1997年   12篇
  1996年   7篇
  1995年   8篇
  1994年   7篇
  1993年   9篇
  1992年   5篇
  1991年   6篇
  1990年   14篇
  1989年   7篇
  1988年   11篇
  1987年   5篇
  1986年   3篇
  1985年   5篇
  1984年   4篇
  1983年   3篇
  1974年   3篇
  1972年   1篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1966年   2篇
  1965年   1篇
  1923年   1篇
排序方式: 共有778条查询结果,搜索用时 311 毫秒
1.
Abstract: The adsorptive characteristics of 5 dialysis membranes for recombinant human erythropoietin (EPO) were studied in vitro in a closed circuit system. For 120 min, EPO added with bovine serum was significantly adsorbed by polymethylmetacrylate (PMMA) and polyacry–lonitrile (PAN) membranes but not by Cuprophan, ethylene vinyl alcohol (EVAL), or polysulfone (PS) membranes. In addition the EPO adsorptive rate, as well as that of β2–microglobulin (β2–MG), was greater with a PMMA membrane than with a PAN membrane. EPO was not detected in the ultrafiltrate at 15 min with 5 membranes. These results indicate that EPO was eliminated by membrane adsorption only with some dialysis membranes.  相似文献   
2.
OBJECTIVE: A joint study was undertaken by the Japanese Society of Renal Cancer to investigate the present status of partial nephrectomy in Japan and to speculate about what may be the indications for partial nephrectomy in patients with renal cell carcinoma. METHODS: Data were tabulated for 469 patients from participating medical institutions and various clinical factors were investigated with regard to disease progression (local recurrence and distant metastasis). RESULTS: Disease progression was observed in 21 patients (4.5%). No significant relation to disease progression was observed for sex, laterality, tumor histology, grade and tumor size. Although patients with solitary tumors displayed excellent prognosis irrespective of tumor diameter, patients with multiple tumors displayed a high likelihood of disease progression. Patients older than 77 years old and patients with imperative indication were found to have a poorer prognosis. CONCLUSION: In patients with solitary tumors, partial nephrectomy can be actively performed, even if the patient displays elective indications and the tumor is >4 cm in diameter. In patients displaying multiple tumors with imperative indications, the decision whether to perform partial nephrectomy should be made by the patients and their physicians after considering the impact on curability and the quality of life.  相似文献   
3.
A case of recurrent medullary thyroid cancer (MTC) was evaluated with123I-MIBG,99mTc(V)-dimercaptosuccinic acid (DMSA), and201Tl scintigraphy. This patient had been operated on for MTC in the right thyroid. Recently a left neck mass was noticed, and was suspected of being a. recurrence of MTC based on increased plasma calcitonin (CT) and carcinoembryonic antigen (CEA). He was operated on for the neck mass which revealed MTC, and papillary thyroid cancer was incidentally found in the left thyroid, but the CT and CEA levels remained high, and remaining MTC tumor was suspected. But the location of the tumor was unknown. Although99mTc(V)-DMSA scintigraphy is generally believed to be superior in sensitivity to123I-MIBG scintigraphy, it did not demonstrate the tumor site but201Tl and123I-MIBG did. Furthermore,123I-MEBG scintigraphy has greater specificity for tumors which arise in the neural crest. Judging from the results of this case and cases reported in the literatures, both123I-MIBG and99mTc(V)-DMSA should be performed in the detection of recurrent MTC.  相似文献   
4.
Summary In this study, we examined histologically the effect of a bone morphogenetic protein (BMP) derived from bovine tooth on the periosteum. Supraperiosteal injection of crude BMP into femurs of Wistar rats (28 day old) resulted in periosteal cell proliferation with subsequent bone and cartilage formation. Moreover, proliferating periosteal cells migrated into injected BMP, and formed both cartilage and bone. These observations show that exogenous BMP stimulates mesenchymal cells of the periosteum to proliferate and differentiate into osteoblasts, and therefore BMP may be one of factors which are involved in differentiation of osteoblasts in the periosteum.  相似文献   
5.
A case of polycythemia vera complicated by chronic renal failure under maintenance hemodialysis requiring parathyroidectory (PTH) for secondary hyperparathyroidism (2° HPT) is reported. A 62 year old female presented with 75000 white blood cells (WBC)/μl, 703×104 red blood cells (RBC)/μl, 23×104 platelets (PLT)/μl, hyperuricemia and hypertension in 1970 and the diagnosis of polycythemia vera was made. Hemodialysis was started in October 1974 for chronic renal failure. Blood cells in peripheral blood rapidly decreased in number after the beginning of dialysis, reaching the level of 10000∼20000 WBC/μl, and 150∼250×104RBC/μl. In August 1988, marked bone resorption in X-ray picture and high serum alkaline phosphatase and parathyroid hormone (PTH) noted along with 17400 WBC/μl, 370×104RBC/μl and 35.9×104PLT/μl. After subtotal PTX removing 3.21g parathyroid gland, serum PTH rapidly fell. At 3 months after PTX, WBC rose to 23600/μl, RBC 372×104/μl and PLT 94.0×104/μl. At 6 months, WBC was to 31000/μl, RBC 429×104/μl and PLT 78.0×104/μl, suggesting an inhibitory action of PTH on not only RBC, but also WBC and PLT.  相似文献   
6.
7.
Gallium scintigraphy was evaluated in 25 patients with adult T-cell leukemia lymphoma (ATLL). Anterior and posterior images were obtained at 72 h after administration of 3 mCi 67Ga-citrate using a gamma camera (Maxi-Camera 400T, General Electric Co.) with a medium energy standard parallel hole collimator. Abnormally high accumulations were observed in 17 out of 25 cases (superficial lymph node, 8; hilar and mediastinal lymph node, 7; paraaortic lymph node, 2; lung, 9; liver, 1; bone, 1). There were 10 malignant lesions detected by 67Ga scintigraphy in 9 out of 17 cases (superficial lymph node, 1; hilar and mediastinal lymph node, 6; paraaortic lymph node, 1; liver, 1; bone, 1). White blood cell count and serum LDH levels were raised in patients with abnormally high accumulations of 67Ga. In conclusion, 67Ga scintigraphy seemed to be a useful examination to detect malignant lesions in patients with ATLL.  相似文献   
8.
Lack of efficient culture systems for hepatitis C virus (HCV) has been a major obstacle in HCV research. Human liver cells grown in a three-dimensional radial-flow bioreactor were successfully infected following inoculation with plasma from an HCV carrier. Subsequent detection of increased HCV RNA suggested viral replication. Furthermore, transfection of HCV RNA transcribed from full-length cDNA also resulted in the production and release of HCV virions into supernatant. Infectivity was shown by successful secondary passage to a new culture. Introduction of mutations in RNA helicase and polymerase regions of HCV cDNA abolished virus replication, indicating that reverse genetics of this system is possible. The ability to replicate and detect the extracellular release of HCV might provide clues with regard to the persistent nature of HCV infection. It will also accelerate research into the pathogenicity of HCV, as well as the development of prophylactic agents and new therapy.  相似文献   
9.
The leukocytotoxic toxin pseudomonal leukocidin, produced by Pseudomonas aeruginosa, was radioiodinated with chloramine-T reagent. Binding of [125I]leukocidin to rabbit polymorphonuclear leukocytes was found to be concentration dependent at 37 degrees C. A Scatchard plot of binding data was linear, indicating that leukocidin binds to a single population of sites. The dissociation constant, KD, was calculated from the Scatchard plot to be 2.5 X 10(-7) M, and the number of binding sites per leukocyte was approximately 4.4 X 10(5). Unlabeled leukocidin or antileukocidin antibody reduced the binding of [125I]leukocidin to the leukocytes. A leukocidin-binding protein was extracted from rabbit polymorphonuclear leukocytes with Triton X-100 and purified by leukocidin-Sepharose 4B affinity column chromatography. Approximately 60 micrograms of binding protein was obtained from 8.1 mg of material extracted from the leukocytes. The binding protein had a molecular weight of about 50,000 as shown by sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis and staining with silver nitrate. Under nondenaturing conditions, its molecular weight was also about 50,000, as shown by gel filtration-Sephadex G-200 chromatography. The 50,000-dalton protein purified in this way from rabbit polymorphonuclear leukocytes competitively inhibited the binding of leukocidin to leukocytes and inactivated leukocidin activity. With equimolar amounts of the 50,000-dalton protein and leukocidin, up to 90% inactivation of leukocidin was observed.  相似文献   
10.
Saliva contains a number of proteins and glycoproteins that protect oral tissues, but little is known about the role of human saliva in innate immunity. Here we showed that human major salivary gland cells constitutively expressed a bacterial pattern recognition receptor, CD14, by immunohistochemistry. Human salivary gland cells in culture express CD14 mRNA and a 55-kDa CD14 protein in, but not on the cells, and secrete a soluble form with the same molecular mass. Human whole saliva contains a 55-kDa CD14, and the concentration of parotid saliva was 10-fold higher than whole saliva, which is comparable to that of serum CD14. Levels of CD14 in unstimulated whole and parotid saliva were unchanged before and after a meal and between unstimulated and stimulated saliva, indicating that saliva CD14 is constitutively secreted into the oral cavity. In contrast, lipopolysaccharide (LPS)-binding protein was below the detectable level. The saliva CD14 is functionally active in that it mediated the activation of CD14-lacking intestinal epithelial cells by LPS in a Toll-like receptor 4-dependent manner. These results suggested that saliva CD14 is important for the maintenance of oral health and possibly intestinal homeostasis.  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