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   6627篇
  免费   255篇
  国内免费   31篇
耳鼻咽喉   91篇
儿科学   152篇
妇产科学   41篇
基础医学   859篇
口腔科学   147篇
临床医学   378篇
内科学   1410篇
皮肤病学   76篇
神经病学   649篇
特种医学   297篇
外科学   1221篇
综合类   28篇
预防医学   226篇
眼科学   133篇
药学   509篇
中国医学   4篇
肿瘤学   692篇
  2023年   49篇
  2022年   87篇
  2021年   127篇
  2020年   77篇
  2019年   100篇
  2018年   111篇
  2017年   116篇
  2016年   116篇
  2015年   135篇
  2014年   149篇
  2013年   191篇
  2012年   354篇
  2011年   373篇
  2010年   180篇
  2009年   185篇
  2008年   382篇
  2007年   391篇
  2006年   397篇
  2005年   410篇
  2004年   409篇
  2003年   314篇
  2002年   379篇
  2001年   147篇
  2000年   154篇
  1999年   180篇
  1998年   85篇
  1997年   86篇
  1996年   58篇
  1995年   84篇
  1994年   50篇
  1993年   60篇
  1992年   108篇
  1991年   87篇
  1990年   80篇
  1989年   59篇
  1988年   65篇
  1987年   61篇
  1986年   64篇
  1985年   59篇
  1984年   47篇
  1983年   42篇
  1982年   37篇
  1981年   28篇
  1980年   32篇
  1979年   37篇
  1978年   28篇
  1977年   20篇
  1974年   16篇
  1973年   19篇
  1969年   13篇
排序方式: 共有6913条查询结果,搜索用时 109 毫秒
1.
Finasteride is standard medical treatment for androgenetic alopecia; however, no large studies with 5 years or more of follow up have been performed in Japan. The authors followed Japanese men with androgenetic alopecia treated with finasteride for 5 years to evaluate long‐term treatment efficacy. Of 903 men treated with finasteride (1 mg/day), 801 patients were evaluated over 5 years by modified global photographic assessment. Although the proportion of improvement was high (99.4%), modified global photographic assessment scores after 5 years of treatment were lower in patients with more advanced disease as measured by the modified Norwood–Hamilton scale. After separating patients into “sufficient” and “insufficient” efficacy groups according to the modified global photographic assessment score after 5 years (scores ≥6 and <6, respectively), multivariate analysis showed that independent risk factors of insufficient efficacy were age at start of treatment of 40 years or more (P = 0.021) and classification on the modified Norwood–Hamilton scale (P < 0.001), whereas presence of stress at start of treatment was a negative predictor (P = 0.025). In conclusion, continuous finasteride treatment for 5 years improved androgenetic alopecia with sustained effect among Japanese. Younger age and less advanced disease at start of treatment were the key predictors of higher finasteride efficacy.  相似文献   
2.
3.
4.
Postoperative empyema and aspergillosis were diagnosed in a 66-year-old man. Since non-operative therapy was not effective, we performed surgery. On the 8th postoperative day, a covered Ultraflex expandable stent (Boston Scientific, Galway, Ireland) was implanted to make a one-way airway for blocking a major air leak from a bronchopleural fistula causing respiratory distress. His general condition improved gradually, and he was discharged 30 days after stenting. In conclusion, we used a covered Ultraflex expandable stent to make an airway to block an air leak. This may be a new application for this stent.  相似文献   
5.
We report a case of infectious endocarditis in a 77-year-old woman who was undergoing maintenance hemodialysis therapy, and who was also having a prosthetic aortic valve replacement. The disease resulted from a local skin infection at the needle puncture site of the arteriovenous fistula. Ampicillin-resistant Staphylococcus aureus was the causal organism. Surgical treatment could not be performed because of associated intracranial hemorrhage due to septic embolism. In spite of intensive treatment with several antibiotics, a ventricular septal abscess just beneath the prosthetic aortic valve progressed to form a ventricular septal fistula. The resultant intracardiac left-to-right shunt led to refractory congestive heart failure. The patient finally died of heart failure. The formation of a ventricular septal fistula is considered to be a rare and extraordinary complication of infectious endocarditis in a hemodialysis patient with aortic valve replacement. Received: July 25, 2001 / Accepted: November 3, 2001  相似文献   
6.
The effect of electric charge on the hepatic disposition of macromolecules was studied in the rat. Charged derivatives of dextran (T-70) and bovine serum albumin (BSA), mitomycin C–dextran conjugates (MMC-D), and lactosaminated BSA (Lac-BSA) were employed as model macromolecules. After intravenous injection, cationic macromolecules were rapidly eliminated from plasma because of their extensive hepatic uptake, while anionic and neutral macromolecules were slowly eliminated. Cationic macromolecules were recovered from parenchymal and nonparenchymal hepatic cells at a cellular uptake (per unit cell number) ratio of 1.4–3.2, while that of Lac-BSA was 14. During liver perfusion using a single-pass constant infusion mode, cationic macromolecules were continuously extracted by the liver, with extraction ratios at steady-state (E ss) ranging between 0.03 and 0.54, whereas anionic and neutral macromolecules were almost completely recovered in the outflow at steady state. The E ss for cationized BSA (Cat-BSA) and cationic MMC-Dcat were concentration dependent and decreased at low temperatures and in the presence of colchicine and cytochalasin B. The possible participation of the internalization process in the uptake of cationic macromolecules by hepatocytes was suggested.  相似文献   
7.
The objective of this study was to assess the in vivo fate of poly(2-(dimethylamino)ethyl methacrylate) (pDMAEMA)-based polyplexes after intravenous administration into mice. Circulation kinetics and tissue distribution in terms of plasmid localization and transfection efficiency were assessed. To gain more insight into the observed biodistribution and gene expression profile, the interaction of pDMAEMA-based polyplexes with blood components (erythrocytes and albumin) was investigated in vitro. In the case of i.v. injection of positively charged polyplexes at a dose of 30 microg DNA most of the radioactivity was found in the lungs and the liver 60 min after injection. In the case of pDMAEMA/DNA polyplexes with a negative charge, uptake occurred mainly by the liver. Administration of positively charged complexes at a 30 microg DNA dose resulted in reporter gene expression primarily in the lungs. Injection of negatively charged complexes and naked plasmid did not result in luciferase expression in any of the organs examined. In vitro turbidity experiments showed the induction of a charge dependent aggregation process upon addition of albumin to the polyplexes pointing out to the involvement of aggregate formation in the dominant lung uptake of the positively charged polyplexes. Also, incubations of polyplexes after pre-incubation with a physiological concentration of albumin with washed erythrocytes confirmed that polyplexes induce the formation of extremely large structures. This paper underlines the need for the design of systems with reduced interaction with blood components to promote the delivery of DNA to target tissues outside the lungs.  相似文献   
8.
Pancreatic metastasis of malignant melanoma is rarely diagnosed while the patient is alive. We report a case of metastatic melanoma of the pancreas in a 35-year-old woman presenting with a solid mass of the pancreas. Her past medical history included a radical hysterectomy 2 years previously for malignant melanoma of the vagina. Twelve months later, lung metastasis was also resected. EUS-guided fine needle aspiration (EUS-FNA) identified that the pancreatic tumor was histologically and immunohistochemically identical to the surgical specimen of her lung neoplasm. Imaging studies including US, CT, and MRI have limited value to distinguish the tumors from primary ductal adenocarcinoma. EUS-FNA can provide tissue diagnosis from pancreatic masses, specifically when other modalities have failed.  相似文献   
9.
This article documents a patient with lung carcinoma that produced three oncofetal antigens including alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), and human chorionic gonadotropin (hCG). Serum AFP, CEA, and hCG-beta-subunit were extremely high--118,000 ng/ml, 133 ng/ml and 0.9 ng/ml, respectively. Immunohistochemical staining of these tumor markers revealed that these proteins were present in different cells. The pattern of lectin affinity electrophoresis of AFP resembled that of hepatocellular carcinoma. Also investigated was the reactivity of serum CEA to monoclonal antibodies against peptide or sugar moieties. Serum CEA values measured by antipeptide monoclonal antibodies were higher than those measured by antisugar monoclonal antibodies. The demonstration of AFP, CEA, and hCG in different tumor cells suggests that three genomes were not reactivated together in a cell, and the lung carcinoma probably consisted of at least three clones of cancer cells with different phenotypes.  相似文献   
10.
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   
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