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   8731篇
  免费   463篇
  国内免费   26篇
耳鼻咽喉   79篇
儿科学   163篇
妇产科学   161篇
基础医学   1069篇
口腔科学   244篇
临床医学   643篇
内科学   2293篇
皮肤病学   139篇
神经病学   537篇
特种医学   314篇
外科学   1256篇
综合类   47篇
一般理论   2篇
预防医学   297篇
眼科学   172篇
药学   614篇
中国医学   8篇
肿瘤学   1182篇
  2023年   74篇
  2022年   142篇
  2021年   238篇
  2020年   110篇
  2019年   147篇
  2018年   155篇
  2017年   151篇
  2016年   143篇
  2015年   142篇
  2014年   158篇
  2013年   240篇
  2012年   367篇
  2011年   360篇
  2010年   191篇
  2009年   198篇
  2008年   337篇
  2007年   356篇
  2006年   326篇
  2005年   373篇
  2004年   359篇
  2003年   323篇
  2002年   335篇
  2001年   336篇
  2000年   338篇
  1999年   296篇
  1998年   118篇
  1997年   91篇
  1996年   76篇
  1995年   80篇
  1994年   77篇
  1993年   60篇
  1992年   245篇
  1991年   222篇
  1990年   239篇
  1989年   222篇
  1988年   194篇
  1987年   158篇
  1986年   152篇
  1985年   141篇
  1984年   88篇
  1983年   86篇
  1981年   51篇
  1979年   68篇
  1974年   38篇
  1973年   54篇
  1972年   50篇
  1971年   48篇
  1970年   43篇
  1969年   71篇
  1968年   53篇
排序方式: 共有9220条查询结果,搜索用时 15 毫秒
1.
2.
The pharmacokinetics of 1-(tetrahydro-2-furanyl)-5-fluorouracil (FT) and its conversion into 5-fluorouracil (FUra) in liver tissue were studied in ten patients with hepatocellular carcinoma (HCC). The plasma concentration of FT after its intravenous injection (dosage: 800 mg) was computerfitted to a bi-exponential function (C = Ae-alpha t + Be-beta t), indicating a two-compartment disposition. The pharmacokinetic parameters did not significantly differ between the five patients with, and the five without cirrhosis of the liver. The plasma concentrations of FUra likewise showed no significant difference between the two groups. The rates of FT degradation in the liver tissue homogenate were similar for four of the patients with cirrhosis (0.10 +/- 0.05 mumol/g liver protein/30 min) and four of those without it (0.13 +/- 0.05). The rates of cytochrome P-450-dependent FUra formation in the microsomal fraction of liver tissue from two patients (1.1 and 1.3 nmol/mg microsomal protein/30 min) were dramatically reduced to less than half of those of two control subjects (2.4 and 2.7). The estimated rates of FUra formation in the soluble fraction (105,000 X g supernatant fraction) from the two patients (0.1 and 0.13 nmol/mg protein/30 min) were almost identical to those from the controls (0.12 and 0.14), suggesting that the rate in the soluble fraction from HCC patients may not be as strongly affected as the rate in the microsomal fraction.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
3.
4.
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   
5.
Although the cause varies widely, we recently experienced a case of constrictive pericarditis of which cause seemed to be traumatic as described below. The patient was a 62-year-old man having a history of epigastric trauma about 20 years ago. Since then, palpitation appeared and he was recently hospitalized in our department for the purpose of receiving an operation under the diagnosis of constrictive pericarditis. At operation, a hematoma was found in the pericardial region, which was considered to have been caused by trauma in the past. Less reports have so far been available concerning trauma-induced constrictive pericarditis and this case thus seemed to be of rarity as well.  相似文献   
6.
Nine main organs in the mouse were studied by ESR spectroscopy at 77K. Manganese ions were readily detected in the pancreas, small intestine, stomach and kidney. In particular, the pancreas gave strong ESR signals for the transition metal, suggesting that Mn(II) plays an important role in pancreatic function. All organs reveal different ESR spectra indicating organ specificity. C-centered radical, R-OO radical and C0Q10 or ascorbate radical are stable in the tissue. In the brain, heart and pancreas, N-centered radical heme-NO adduct was detected at 6 and 24 h after excision since common process is involved in tissue degeneration and ESR is sensitive to proteolysis and necrosis of tissues. In endotoxemia and/or CDE-diet-induced pancreatic lesions, R-OO radical and Mn(II) ion were detected in the signal at 77K. By the spin-trapping method (DMPO) at 25 degrees C, DMPO-OH adduct and 3-Line and 6-Line were detected in CDE diet-induced acute pancreatitis. These results suggest that damaged pancreatic tissues are in a highly oxidative environment that probably contains oxygen radicals, and that free radicals are considered to play an important role in the development of pancreatic lesions.  相似文献   
7.
The incidence of hepatic venous stenosis is higher in partial liver transplantation. New methods for hepatic venous reconstruction in left liver transplantation, which secure wide anastomosis, were devised and are reported here. In the graft, the right side of the middle hepatic vein or the left side of the left hepatic vein was cut longitudinally and a rectangular-shaped vein patch was attached for venoplasty. In the recipient, after the left and middle hepatic veins were joined, the right side of the middle hepatic vein was cut toward the closed right hepatic vein, making a horizontal cavotomy for anastomosis. Of 92 patients who underwent conventional hepatic vein reconstruction, 3 were complicated by hepatic venous stenosis (median follow-up 43 months). By contrast, there were no hepatic vein complications in the 20 patients who underwent the new technique (7 months). The current method appears to be technically feasible for outflow reconstruction in left liver graft transplantation.  相似文献   
8.
Patients with porcelain aorta carry a high risk of cerebral as well as systemic embolism during cardiac surgery. Here we describe a case of severe aortic stenosis and coronary artery disease combined with the circumferentially calcified aorta. The patient was a 77-year-old man who successfully received four coronary artery bypass grafts with in situ arterial grafts without clamping the aorta and aortic valve replacement. Aortic valve replacement and two distal coronary artery anastomoses to the left circumflex artery and obtuse marginal branch were performed under cardiac arrest during hypothermic perfusion with endoaortic balloon occlusion, followed by partial endarterectomy and closure of the aorta buttressed with bovine pericardium under deep hypothermic circulatory arrest. While rewarming, the other two distal coronary anastomoses to the left anterior descending artery and diagonal branch were done on the beating heart in order to minimize cardiac arrest time. On-pump beating heart coronary artery bypass grafting (CABG) can be useful especially for combined complex cardiac surgery.  相似文献   
9.
A 68-year-old man noticed weakness in both legs, which worsened rapidly with additional urinary disturbance. At the time of admission, a neurological examination revealed spastic paraplegia. Sensation was intact. Magnetic resonance imaging (MRI) did not show any lesions in the spinal cord. Thereafter, sensory disturbance under Th5 level and weakness in both hands developed gradually. Seven months after the onset, he noticed pain of the right upper arm. MRI showed an epidural mass at the level between the lower cervical and the upper thoracic spine. Histological examination of the epidural mass revealed Ki-1 lymphoma. In this case, the diagnosis was difficult, because lymphoma did not present epidural mass in the early stage. We speculate that spinal epidural lymphoma might disturb venous circulation and cause myelopathy in this patient.  相似文献   
10.
MRI of ossification of ligamentum flavum.   总被引:11,自引:0,他引:11  
Magnetic resonance imaging of 28 patients with radiological and/or histopathologically proved ossification of the ligamentum flavum (OLF) was reviewed. The locations of OLF were cervical (n = 4), thoracic (n = 22), and lumbar (n = 2). On T1- and T2-weighted images, OLF demonstrated low signal intensity. Areas of high or intermediate signal intensity within the OLF on T1-weighted images were observed in three cases and were interpreted to be due to fat infiltration. In six cases, high intensity areas in the spinal cord caused by compressing OLF were demonstrated on T2-weighted images. Gadolinium-diethylenetriamine pentaacetic acid, which was used in four cases, showed cord enhancement at the level of compression by OLF in three cases.  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