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   6973篇
  免费   301篇
  国内免费   24篇
耳鼻咽喉   69篇
儿科学   269篇
妇产科学   441篇
基础医学   1189篇
口腔科学   148篇
临床医学   513篇
内科学   1183篇
皮肤病学   376篇
神经病学   549篇
特种医学   300篇
外科学   894篇
综合类   63篇
一般理论   4篇
预防医学   255篇
眼科学   173篇
药学   362篇
肿瘤学   510篇
  2022年   46篇
  2021年   97篇
  2020年   62篇
  2019年   86篇
  2018年   88篇
  2017年   71篇
  2016年   90篇
  2015年   100篇
  2014年   142篇
  2013年   203篇
  2012年   271篇
  2011年   306篇
  2010年   203篇
  2009年   188篇
  2008年   296篇
  2007年   291篇
  2006年   323篇
  2005年   333篇
  2004年   343篇
  2003年   304篇
  2002年   301篇
  2001年   159篇
  2000年   155篇
  1999年   146篇
  1998年   84篇
  1997年   52篇
  1996年   45篇
  1995年   48篇
  1994年   40篇
  1993年   43篇
  1992年   65篇
  1991年   70篇
  1990年   58篇
  1989年   57篇
  1988年   68篇
  1987年   71篇
  1986年   57篇
  1985年   71篇
  1984年   53篇
  1983年   34篇
  1979年   55篇
  1975年   39篇
  1971年   31篇
  1969年   32篇
  1932年   31篇
  1931年   35篇
  1930年   35篇
  1928年   42篇
  1913年   43篇
  1912年   30篇
排序方式: 共有7298条查询结果,搜索用时 15 毫秒
21.
22.
23.
From 1985 through 1987, we diagnosed acute hepatic failure in 13 patients. Spontaneous recovery occurred in three of these patients. Eight patients underwent liver transplantation, five of whom survived and three of whom died. In addition, two patients died before undergoing transplantation. The survival rate of 62% was better than that among our previous series of similar patients. This improvement seems to be related to the use of orthotopic liver transplantation as a therapeutic alternative among these patients. One of the three patients who died after liver transplantation had normal liver function, but respiratory failure caused by Pneumocystis carinii developed 4 months after the transplantation. The surgical procedure was less difficult in patients with acute fulminant hepatitis than in those with chronic liver disease because fewer problems arose from adhesions, venous collaterals, and ascites. The emerging role of orthotopic liver transplantation in patients with acute hepatic failure is demonstrated by the improvement of survival rates observed by various groups, including ours, when this therapeutic modality is available.  相似文献   
24.
Introduction and background A 3-year-old Bosnian girl with a large symptomatic brainstem and multiple supratentorial cavernous angiomas, who underwent neurosurgical treatment, is presented. As multiple cavernomas are more common in familial cases, genetic analyses and neuroradiological imaging were performed in the patient and her parents to see whether there was any evidence for inheritance. This information is important for genetic counseling and provision of medical care for at-risk relatives. Currently, no recommendation is available on how to manage these cases.Results Genetic analyses demonstrated a novel CCM1 frameshift mutation (c.1683_1684insA; p.V562SfsX6) in the child and the asymptomatic 27-year-old mother. Sensitive gradient-echo magnetic resonance imaging of the mother revealed multiple supratentorial lesions, whereas analogous imaging of the father showed no pathological findings.Conclusion This case exemplifies that seemingly sporadic cases with multiple lesions might well be hereditary and that presymptomatic genetic testing of family members may identify relatives for whom clinical and neuroradiological monitoring is indicated.  相似文献   
25.
Summary We have identified cells which secrete human chorionic gonadotropin (HCG) of cultures if first trimester placental villi. As a first step, we identified epithelial cells using a new monoclonal antibody. We then added HCG antibodies to the cultured cells. We found that syncytiotrophoblast (and not cytotrophoblast), Hofbauer cells and some mesenchymal cells stained with HCG antibodies.  相似文献   
26.
The aim of the present study was to explore cell biological characteristics of normal breast, benign proliferative breast diseases and noninvasive breast malignancies based on the recently published adult progenitor cell concept from our group. Here, we investigated the proliferative activity of CK5/14(+), CK8/18/19(+) and alpha-smooth muscle actin(+) cellular phenotypes encountered in normal mammary gland, in a series of usual ductal hyperplasias and early malignant breast diseases, such as atypical ductal and lobular hyperplasias, as well as ductal and lobular in situ carcinomas. Immunohistochemical double labeling was performed on frozen sections from diagnostic breast biopsies by using antibodies to basal cytokeratins (CK5/14), glandular cytokeratins (CK8/18/19), smooth muscle actin and the Ki-67 antigen (MIB1). Normal breast tissues and usual ductal hyperplasias were characterized by a heterogeneous cellular composition of the growth fraction. The proliferative cell compartment consisted of CK8/18/19(+) glandular and, in a variable proportion, CK5/14(+) progenitor phenotypes. In contrast, noninvasive breast malignancies were composed of a monotonous proliferation of CK 8/18/19(+) neoplastic glandular cells. These findings indicate a significant role of progenitor cells in the development of benign proliferative breast diseases and lend support to the view that malignant transformation in the human breast usually occurs in a cell committed to the glandular lineage. Our results provide cell kinetic support to the functional progenitor cell hypothesis, and we propose this concept as an operative model for understanding benign proliferative and malignant breast diseases.  相似文献   
27.
In this study we evaluated the association between cytomegalovirus infection alone or in relation to human leukocyte antigen matching and the development of vanishing bile duct syndrome, a form of chronic hepatic allograft rejection. A total of 81 consecutive liver transplant recipients were studied. Cytomegalovirus infection developed in 46 recipients (57%), and vanishing bile duct syndrome occurred in 9 recipients (11%). Cytomegalovirus infection developed in only five of the nine patients with vanishing bile duct syndrome. Univariate analysis of pretransplant recipient/donor cytomegalovirus serological tests and human leukocyte antigen typing showed they were not significant risk factors for the development of vanishing bile duct syndrome. Time-dependent analysis of cytomegalovirus infection after transplantation as a risk factor for vanishing bile duct syndrome, in a multivariate analysis with human leukocyte antigen match, showed no statistical significance. In our study, no association was found between cytomegalovirus infection alone or in relation to class I or II human leukocyte antigen match and the subsequent development of vanishing bile duct syndrome.  相似文献   
28.
This review summarises the occurrence of herpesvirus infections in pinnipeds and data from investigations carried out by the authors. These data demonstrate that herpesvirus isolates collected from harbour seals (Phoca vitulina Linnaeus, 1758) during the 1988 seal epidemic were almost indistinguishable from feline herpesvirus 1 and that Antarctic Weddell's seals (Leptonychotes weddelli Lesson, 1826) carry antibodies against seal herpesvirus from the north-western Europe seal epidemic. The significance of herpesvirus infections in seals is discussed.  相似文献   
29.
30.
PURPOSE, MATERIAL AND METHODS: The dose calculation accuracy of the voxel-based Monte Carlo (VMC++) electron dose module of Oncentra MasterPlan (Nucletron B.V., Veenendaal, The Netherlands) was verified by measurements in homogeneous water phantoms. RESULTS: Measured and calculated dose maxima on the central beam axis (calculations with 10,000-20,000 incident electron histories per cm(2)) agree well using standard applicator configurations as well as individually shaped inserts. Profile scans with higher electron energies (>/= 15 MeV) reveal differences up to 5% especially in the penumbra region. Depth dose curves agree best in the vicinity of maximum depths. In the buildup region energy-dependent differences up to 5% in both directions could be observed. In the decay region of depth dose curves calculated doses were up to 10% higher than measured values. CONCLUSION: Good VMC++ accuracy combined with moderate computing times of 1-15 min per beam satisfy all clinical needs. VMC++ allows, for the first time, accurate routine dose evaluations of radiation therapy with electrons. Adequate positioning of the dose reference point is essential. Even small displacements may significantly influence the calculation of monitor units.  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