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   34146篇
  免费   1713篇
  国内免费   157篇
耳鼻咽喉   438篇
儿科学   605篇
妇产科学   609篇
基础医学   4557篇
口腔科学   1194篇
临床医学   2680篇
内科学   8036篇
皮肤病学   826篇
神经病学   2502篇
特种医学   1372篇
外科学   5563篇
综合类   230篇
一般理论   3篇
预防医学   1079篇
眼科学   584篇
药学   2379篇
中国医学   49篇
肿瘤学   3310篇
  2022年   291篇
  2021年   665篇
  2020年   314篇
  2019年   480篇
  2018年   655篇
  2017年   457篇
  2016年   541篇
  2015年   618篇
  2014年   809篇
  2013年   906篇
  2012年   1460篇
  2011年   1544篇
  2010年   866篇
  2009年   780篇
  2008年   1375篇
  2007年   1483篇
  2006年   1513篇
  2005年   1525篇
  2004年   1450篇
  2003年   1406篇
  2002年   1409篇
  2001年   1233篇
  2000年   1398篇
  1999年   1209篇
  1998年   412篇
  1997年   293篇
  1996年   313篇
  1995年   280篇
  1994年   247篇
  1993年   225篇
  1992年   798篇
  1991年   759篇
  1990年   679篇
  1989年   697篇
  1988年   678篇
  1987年   664篇
  1986年   673篇
  1985年   594篇
  1984年   428篇
  1983年   349篇
  1979年   339篇
  1978年   233篇
  1977年   199篇
  1975年   198篇
  1974年   226篇
  1973年   207篇
  1972年   197篇
  1971年   209篇
  1970年   203篇
  1969年   224篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
51.
Idiopathic membranous nephropathy in two brothers   总被引:1,自引:0,他引:1  
Idiopathic membranous nephropathy has been reported rarely to develop in genetic association with certain HLA antigens. This paper describes two male siblings presenting with nephrotic syndrome with histologically proven membranous nephropathy. The younger brother maintained a normal renal function with slight proteinuria during the 3 years of follow-up, but the older one experienced a rapid decline in renal function and had to be put on maintenance hemodialysis. No clinical evidence of contributory underlying disease such as malignancy or systemic lupus erythematosus could be found. HLA typing was carried out in the two patients and in members of their family. Several HLA antigens were found to be shared by the two patients. However, the HLA antigens which have been reported to be associated with idiopathic membranous nephropathy were not found in either of them.  相似文献   
52.
Summary The histogenesis of stromal cells in capillary hemangioblastoma has been the subject of debate. The light and electron microscopic studies of hemangioblastomas presented here showed pericytic and leiomyoblastic features in stromal cells. Cells cultured by the monolayer method showed similar features to those of the original tumors. Immunohistochemical studies for glial fibrillary acidic protein and factor VIII/von Willebrand factor indicated that stromal cells were antigenically distinct from astrocytes and endothelial cells. These findings suggest that stromal cells are closely related to pericytes and smooth muscle cells, and support Rhodin's speculation that pericytes serve as a precursor to smooth muscle cells.  相似文献   
53.
The byproducts P-1 and P-2, which were produced during the synthesis of porcine secretin, were isolated in pure form from the crude secretin by HPLC. These were identified by a combination of amino acid analysis, enzymatic digestion, and isocratic or linear gradient reversed-phase (RP)-HPLC. The amino acid compositions of P1 and P2, determined by amino acid analysis after acid hydrolysis, were found to be the same as those of porcine secretin without distinction between L-and D-amino acids. But, HPLC of their digestive fragments with trypsin and alpha-chymotrypsin differed from that of secretin. The fragments, S7-12 of P-1 and S13-21 of P-2 were determined to be different from the corresponding fragments obtained from secretin by HPLC analysis of their digestive fragments. The amino acid composition of each acid hydrolysate, following digestion with D-amino acid oxidase, was found to have less leucine or alanine content than secretin. The HPLC analysis of the fragments from P-1 and P-2 by tryptic and alpha-chymotryptic digestion showed that they are the same as those from synthetic D-Leu10 secretin or D-Ala17 secretin, respectively. Consequently, P-1 and P-2 are concluded to be the secretin diastereoisomers, D-Leu10 and D-Ala17 secretin, respectively.  相似文献   
54.
Binding of lectins to the water-insoluble fractions from human, monkey and mouse lenses was investigated. Lectins bound to glycoproteins blotted from SDS-polyacrylamide gels onto nitrocellulose paper. Use of multiple lectins showed that glycoproteins with apparent molecular weights of about 120 000 and 90 000 were present in all species. These proteins were found in the urea-insoluble fraction. Multiple lectins also bound to two bands around 67 000 and 63 000 molecular weight in both human and monkey lens fractions as well as a urea-soluble band at about 140 000. A 35 000 MW glycoprotein containing N-acetyl-galactosamine and fucose sugars was present in the capsule-epithelium of monkey lenses but was not detected in cortical or nuclear fractions. Glycoproteins from normal and cataractous mice were identified using this new methodology and compared with previously published work using sodium borohydride labelling of glycoproteins. Because of the numerous glycoproteins that can be detected and the ability to assign sugar residues to individual proteins, the lectin-binding method is a powerful tool to investigate lens glycoproteins.  相似文献   
55.
A 65-year-old Japanese man was hospitalized because of acute hepatitis and severe cholestasis due to hepatitis E virus (HEV) infection combined with a drug reaction to a cold preparation. He died of disseminated intravascular coagulation and severe intestinal bleeding due to systemic cytomegalovirus reactivation following the development of severe eruptions with marked eosinophilia due to drug hypersensitivity to taurine and ursodeoxycholate preparations. The close interaction between viral infection or reactivation and drug hypersensitivity was considered as a pathophysiology in this case, which emphasizes the need for further study of the immunological mechanism of the interaction.  相似文献   
56.
A 23-year-old man was admitted for an aortic root aneurysm with mild aortic valve regurgitation (AR) and a small pressure gradient. At surgery, findings of aortic valve, one normal left posterior commissure and very rudimentary right anterior commissure, was compatible with the uni-commisural aortic valve. Aortic root replacement with valve-sparing technique was performed. Four years later no residual AR was observed.  相似文献   
57.
OBJECTIVE: The purpose of this study was to characterize the etching behavior of titanium in concentrated sulfuric acid and discuss its application on surface modification of titanium for biological use. METHODS: Commercially pure titanium (cpTi) plate was etched in 48% H2SO4 at RT -90 degrees C for 0.25-8 h. The weight loss was derived from the weight differences before and after etching. The surfaces after etching were characterized by surface roughness, X-ray diffractometry, and scannning electron spectroscopy. The apparent activation energy of the dissolution of cpTi into acid was derived from an Arrhenius plot of the rate of weight loss versus the acid temperature. RESULTS: The surface roughness of cpTi increased with the acid temperature and etching time. The surface roughness was strongly related to the weight loss. The weight loss increased drastically with the acid temperature after an initial period, which shortened with increasing acid temperature. The apparent activation energy for the dissolution of cpTi in H2SO4 was derived as 67.8 kJ/mol. SIGNIFICANCE: This study indicates that etching with concentrated sulfuric acid is an effective way to modify the surface of titanium for biological applications.  相似文献   
58.
59.
Introduction: One of the causes of pain during insertion of the colonoscope is stretching of the mesenterium by loop formation. The degree of pain differs according to the type of loop formation. Our aims were to study the accuracy of the colonoscopist’s assessment of the presence and type of loop formation and to study the degree of pain in relation to the type of loop by administering the visual analog scale (VAS). Methods: Two hundred and fifty‐seven consecutive patients were enrolled. All procedures were performed by two experienced colonoscopists who were blind to magnetic endoscope imaging view. After the colonoscopy, the colonoscopist was asked to assess the presence and type of loop formation. The degree of pain was assessed using the VAS. Results: The accuracy of estimating N loop, alpha loop, absence of loop formation and U loop was each over 70%. The accuracy of estimating gamma and splenic loop was significantly lower than the accuracy of estimating U loop. Colonoscopy was significantly more painful in women than in men. The degree of pain was significantly higher upon formation of reverse alpha loop and gamma and splenic loop than upon formation of N loop and U loop. Conclusions: Upon formation of reverse alpha loop or gamma and splenic loop, patients experienced more pain and it was difficult for the endoscopists to assess these loops. As women had severe pain compared with men, the use of a pediatric colonoscope or higher dosage of sedation in women should be considered.  相似文献   
60.
Since the prevalence and clinical characteristics of young-onset hypertension are still to be elucidated, we performed targeted-screening at an annual university health check-up for two consecutive years. Out of 16,464 subjects in 2003 and 17,032 in 2004 that were aged less than 30 years, 22 and 26 students (all males) exhibited high blood pressure (BP), respectively, on three occasions during casual BP measurements at the Tohoku University Health Center (systolic and diastolic BP of 140 and/or 90 mmHg or greater, respectively). These students were asked to measure their BP at home, and 9 subjects in total were diagnosed as having essential hypertension (EH). The remaining students were diagnosed as having white coat hypertension (WCH). In 8 out of 9 EH students, their father and/or mother had also been treated with antihypertensive medication. Adjustment by attendance ratio for each BP measurement suggested that the incidence of EH was around 0.1% and that of hypertension (EH and WCH) was around 0.5% in university students aged less than 25 years, since most of the subjects and hypertensive students were between 18 and 24 years old. Body mass index of the EH, which was more than 25 kg/m2 (overweight), was significantly higher than that with WCH. In conclusion, the combination of repeated casual BP measurements and home BP effectively identified young-onset EH. The clinical parameters indicated that male gender, genetic background, and excessive weight were risk factors for young-onset hypertension.  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