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   4074篇
  免费   225篇
  国内免费   50篇
耳鼻咽喉   8篇
儿科学   112篇
妇产科学   27篇
基础医学   583篇
口腔科学   87篇
临床医学   261篇
内科学   1165篇
皮肤病学   22篇
神经病学   252篇
特种医学   180篇
外科学   749篇
综合类   19篇
预防医学   80篇
眼科学   23篇
药学   221篇
中国医学   6篇
肿瘤学   554篇
  2023年   37篇
  2022年   68篇
  2021年   135篇
  2020年   65篇
  2019年   76篇
  2018年   142篇
  2017年   88篇
  2016年   115篇
  2015年   129篇
  2014年   164篇
  2013年   183篇
  2012年   351篇
  2011年   352篇
  2010年   174篇
  2009年   158篇
  2008年   256篇
  2007年   289篇
  2006年   268篇
  2005年   215篇
  2004年   225篇
  2003年   237篇
  2002年   194篇
  2001年   35篇
  2000年   34篇
  1999年   42篇
  1998年   52篇
  1997年   35篇
  1996年   34篇
  1995年   31篇
  1994年   19篇
  1993年   26篇
  1992年   31篇
  1991年   11篇
  1990年   13篇
  1989年   8篇
  1988年   11篇
  1987年   14篇
  1986年   3篇
  1985年   5篇
  1984年   6篇
  1983年   2篇
  1982年   2篇
  1980年   1篇
  1979年   2篇
  1977年   2篇
  1975年   2篇
  1972年   1篇
  1971年   1篇
  1970年   2篇
  1967年   1篇
排序方式: 共有4349条查询结果,搜索用时 15 毫秒
71.
Journal of Natural Medicines - The lycopene content of tomatoes is important because of its effects on vital physiological functions such as improvement of glucose tolerance and non-alcoholic fatty...  相似文献   
72.
We describe herein a case of unilateral pulmonary agenesis (PA) with oesophageal atresia (EA)/tracheoesophageal fistula (TEF) that was diagnosed prenatally and repaired by esophagoesophagostomy with stable postoperative course. The patient was born at 34 weeks gestation, after ultrasonography at 22 weeks gestation showed possible right-sided diaphragmatic eventration or PA and EA was subsequently suspected due to hydramnios. The initial X-ray showed mediastinal shift to the right, and coil up sign of the nasogastric tube, without intracardiac anomaly. Immediately after the diagnosis of EA/TEF and unilateral PA on day 0, the patient was intubated in the operating room, and a gastrostomy tube was placed. After pulmonary status stabilized, at 4 days old, EA/TEF was repaired through a thoracotomy in the right 4th intercostal space. The right main bronchus was noted to continue into the distal oesophagus; this fistula was ligated and divided, and a single-layer esophagoesophagostomy was performed under mild tension with one vertebral gap. The neonate was maintained on mechanical ventilation and gradually weaned to extubation at 7 days old. The postoperative course was uneventful, with the exception of prolonged jaundice that emerged at 3 months old. Laparoscopic cholangiography at that time excluded biliary atresia, and jaundice resolved spontaneously. The patient has not shown any respiratory symptoms or feeding difficulties as of the 12-month follow-up.  相似文献   
73.
Subfertility and infertility are two major reproductive health problems in human and domestic animals. The contribution of the genotype to these conditions is poorly understood. To examine the genetic basis of male subfertility, we analyzed its relationship to sperm morphology in B10.MOL‐TEN1 mice, which shows high‐frequencies (about 50%) of morphologically abnormal sperm. Drastic histological changes were also found in the testis of the B10.MOL‐TEN1. Segregation analysis showed that the abnormal sperm phenotype in B10.MOL‐TEN1 was inherited and was predictably controlled by at least three loci. We also found that male fertility of this strain was normal. These findings indicate a complicated relationship between sperm morphology and male subfertility.  相似文献   
74.
Inflammatory pseudotumor of the liver is a rare benign lesion, but exploratory laparotomy and a hepatectomy are often performed unnecessarily after various misdiagnoses, including liver abscess, hepatocellular carcinoma, metastatic liver tumor, and cholangiocarcinoma. We present a case of hepatic inflammatory pseudotumor in a 17-year-old man in whom diagnosis was confirmed by liver needle biopsy under ultrasonographic tomography (UST) guidance. He had complained of fever and right hypochondralgia 2 months after being operated for appendicitis. He was admitted to our hospital because of the persistence of these symptoms and the presence of a hepatic mass lesion detected by UST. He had hepatomegaly, with tenderness; leukocytosis and elevated erythrocyte sedimentation rate and C-reactive protein level were noted. UST showed a hypoechoic mass in the liver and pre-contrast computerized tomography (CT) revealed a low-density area with an ill defined margin, which was barely enhanced by the contrast medium. On the basis of the patient's clinical symptoms and the laboratory data and imaging studies, the presence of a liver abscess was suspected and antibiotics were administered. One month after the initiation of the antibiotic therapy, UST demonstrated that the portal vein had dilated serpiginously and penetrated into the mass. As the heterogeneous appearance displayed by post-enhanced CT indicated the need for a differential diagnosis of the hepatic mass lesion to rule out hepatocellular carcinoma, percutaneous needle biopsy was performed, under UST guidance. Histopathological examination demonstrated marked infiltration of plasma cells and fibrosis, findings which were consistent with those of hepatic inflammatory pseudotumor. There was a spontaneous reduction of the hepatic pseudotumor without continuous antibiotics and this reduction was documented on follow-up UST and CT. Received: June 30, 1999 / Accepted: December 17, 1999  相似文献   
75.
76.
77.
BACKGROUND: The effects of chronic hypoxia on cardiac membrane fatty acids and on lipid peroxidation were examined, as well as the effect of l-carnitine (LCAR), which suppresses lipid peroxidation, on this process. METHODS AND RESULTS: Four-week-old Sprague-Dawley rats were exposed to 10% oxygen for 14 days ("Hypoxia"), and then to 100% oxygen for 12 h (O2). LCAR (200 mg/kg) was administered by intraperitoneal injection daily for 2 weeks. Fatty acid composition, malondialdehyde (MDA) as a lipid peroxidation product, and antioxidants (superoxide dismutase (SOD), glutathione peroxidase and catalase) were measured. The concentration of linoleic acid was lower, and that of docosahexaenoic acid, which has more double bonds than linoleic acid, was increased in hypoxic hearts. SOD activity decreased in hypoxia, whereas MDA was unchanged, but significantly increased in "Hypoxia"+O2. LCAR reduced the increase in MDA, and had no effect on SOD activity or fatty acid composition. The administration of LCAR caused an increase in the ventricular levels of acetylcarnitine. CONCLUSIONS: These results suggest that chronic hypoxia changes the cardiac fatty acid composition of juvenile rats to fatty acids that contain more double-bonds and reduce SOD activity, and that lipid peroxidation was augmented by exposure to oxygen.  相似文献   
78.
The androgen insensitivity syndrome (AIS) is the most common cause of male undermasculinization and is typically caused by mutations in the AR gene. Affected individuals may exhibit either complete external feminization (complete AIS) or a partial phenotype (partial AIS). Here we describe monozygotic twins diagnosed with complete AIS who each possess two substitutions (C-->G at position 2930 and T-->C at position 2955, both in exon 7), leading to Phe(856)Leu and Ser(865)Pro mutations, respectively. Neither parent was found to be a carrier for these mutations, indicating that the double mutation arose de novo. Both mutations were recreated by site-directed mutagenesis and compared functionally with the wild-type receptor. The Phe(856)Leu mutation did not affect androgen binding when expressed in COS-1 cells, nor did this mutation decrease androgen-dependent trans-activation in transfected HeLa cells. However, the Ser(865)Pro mutation completely ablated androgen binding and trans-activation. In this study we demonstrate that the replacement of serine by proline at position 865 is sufficient in itself to cause complete AIS in these twins. Analyses of nuclear receptor structures suggest that this mutation is likely to perturb the conformation of helix 10/11, which plays a role in ligand binding, dimerization, and receptor activation. To our knowledge this is the first confirmed instance of AIS (complete or partial) due to an AR mutation occurring in twins. Furthermore, the phenotype was associated with two mutations that were both novel in nature.  相似文献   
79.
80.
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