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   2891299篇
  免费   222933篇
  国内免费   5480篇
耳鼻咽喉   39003篇
儿科学   96134篇
妇产科学   80348篇
基础医学   410602篇
口腔科学   85879篇
临床医学   259306篇
内科学   559259篇
皮肤病学   64262篇
神经病学   229001篇
特种医学   112389篇
外国民族医学   698篇
外科学   439103篇
综合类   70414篇
现状与发展   6篇
一般理论   1017篇
预防医学   220477篇
眼科学   68907篇
药学   215791篇
  8篇
中国医学   6436篇
肿瘤学   160672篇
  2018年   30726篇
  2017年   23632篇
  2016年   26186篇
  2015年   29840篇
  2014年   41506篇
  2013年   61759篇
  2012年   84762篇
  2011年   89342篇
  2010年   52866篇
  2009年   49625篇
  2008年   83796篇
  2007年   88778篇
  2006年   89552篇
  2005年   86260篇
  2004年   84113篇
  2003年   80302篇
  2002年   77903篇
  2001年   140993篇
  2000年   145039篇
  1999年   121409篇
  1998年   32902篇
  1997年   29275篇
  1996年   29227篇
  1995年   28205篇
  1994年   26255篇
  1993年   24425篇
  1992年   96152篇
  1991年   93415篇
  1990年   90575篇
  1989年   87375篇
  1988年   80477篇
  1987年   78889篇
  1986年   74966篇
  1985年   71964篇
  1984年   53329篇
  1983年   45801篇
  1982年   26391篇
  1981年   23610篇
  1979年   49436篇
  1978年   34096篇
  1977年   28990篇
  1976年   27197篇
  1975年   28810篇
  1974年   35118篇
  1973年   33769篇
  1972年   31182篇
  1971年   29254篇
  1970年   27043篇
  1969年   25346篇
  1968年   23346篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
991.
A murine monoclonal antibody PASE/4LJ to prostatic acid phosphatase (PAP) was used to immunostain a wide variety of sections of benign and malignant tissues (654 blocks). Non-neoplastic adult and fetal prostatic glands, primary and metastatic prostatic carcinomas, and scattered cells in prostatic and penile urethra were positive. Rat, dog and rabbit prostates were negative. Nine of 400 tumours of non-prostatic origin showed some positivity: 6/36 carcinoids, 1/9 islet cell tumours, 1/55 ovarian adenocarcinomas (serous) and one carcinosarcoma of the lung (epithelial portion). Positive staining was seen in islet cells in 4/5 specimens of normal pancreas, and in 4/9 blocks of normal pancreas surrounding a pancreatic tumour. Loops of Henle, maculae densae, and distal tubules in 10/10 fetal and 2/9 adult kidneys were also positive, with proximal tubules and collecting ducts negative. All other 159 blocks of non-neoplastic adult and fetal tissues were negative. The antibody was also affinity purified from ascitic fluid, and shown not to inhibit the enzyme activity of prostatic acid phosphatase.  相似文献   
992.
131 patients with resectable, node-positive breast cancer were treated at the National Institute for Cancer Research of Genoa, Italy with a systemic adjuvant regimen based on 14 cycles of chemotherapy, immunostimulation with levamisole, and--for postmenopausal patients--hormone therapy with tamoxifen. The present evaluation is performed eleven years after the admission of the first patient: so far, 75 patients (57.3%) have relapsed and 52 (39.7%) have died. An analysis of prognostic factors for relapse and death shows that the number of positive axillary lymph nodes and the dimension of the primary tumor are significantly associated with survival and relapse-free survival, while age and menopausal status are not.  相似文献   
993.
Sclerotherapy of varicose veins and telangiectasia should be preceded by a directed medical history and physical examination. Factors including the presence of significant venous disease should prompt a more extensive evaluation. Of the physical examination techniques and noninvasive technologies available, Doppler ultrasound provides the most pertinent information, but the potential uses of each method are described.  相似文献   
994.
Summary: T cells and natural killer (NK) cells are presumed to share a common intrathymic precursor. The development of conventional a|3 T lymphocytes begins within the early fetal thymus, after the colonization of multipotent CDl1 71 precursors. Irrevocable commitment to the T lineage is marked by thymus-induced expression of CD25. However, the contribution of the fetal thymus to NK lineage commitment and differentiation remains largely unappreciated. Recently, we demonstrated that the development of functional mouse NK cells occurs first in the fetal thymus. Moreover, the appearance of mature fetal thymic NK cells (NK1.1+/CD 117-) is preceded by a thymus-induced developmental stage (NKl.1+/CD1 17+) that marks lineage commitment of multipotent hematopoietic precursors to the T and NK-cell fates. Commitment to the T/NK bipotent stage is induced by fetal thymic stroma, but is not thymus dependent. Recent data indicate that CD90+/CD117lo fetal blood prothymocytes exhibit NK lineage potential and are phenotypically and functionally identical to fetal thymic NK1,1+/CD1 17+ progenitors. This finding also indicates that full commitment of circulating precursors to the T-cell lineage occurs after thymus colonization. In this review, we discuss recent insights into the cellular and molecular events involved in fetal mouse T and NK lineage commitment and differentiation to unipotent progenitors.  相似文献   
995.
Summary. In this study, we have examined our records for the isolation of Candida tropicalis from clinical specimens of patients with heterogeneous clinical presentations during the past 5 years. We have found that this species ranks third among all yeasts in frequency of isolation from clinical specimens and that the trend of recovery from the specimens is rising over the years. The isolation rate of C. tropicalis was highest from urine specimens (36%) followed by respiratory specimens (22%). The frequency of isolation of C. tropicalis from vaginal specimens was relatively high (14%), however the trend was declining over the years. In general, the high recovery of Candida tropicalis from clinical specimens of patients with variable disease supports the views of this organism being a major pathogen.
Zusammenfassung. Die Studie basiert auf einer Durchsicht der Patientenarchive der letzten fünf Jahre auf die Isolationshäufigkeit von Candida tropicalis aus klinischen Untersuchungsmaterialien von Patienten mit unterschiedlichen klinischen Krankheitsbildern. Diese Hefeart war die dritthäufigste mit steigender Tendenz über die Jahre. Die Isolierungsrate von C. tropicalis war am höchsten aus Urin (36%), gefolgt von Respirationstrakt-Materialien (22%). Die Isolationshäufigkeit aus dem hinteren Scheidengewölbe war relativ hoch (14%), nahm jedoch mit den jahren ab. Allgemein unterstreicht die hohe Isolationsrate von C. tropicalis aus klinischen Untersuchungsmaterialien die ätiologische Bedeutung dieses Erregers.  相似文献   
996.
为探讨脂质过氧化损伤及自由基在新生儿硬肿症发病机理中的作用,将观察对象分为疾病组和对照组,疾病组于入院时,对照组于出生后1周内取静脉血检测血浆脂质过氧化物及红细胞超氧化物歧化酶含量。  相似文献   
997.
998.
There has been a remarkable change in the scenario of therapeutic apheresis in the last 14 years in India. The crude method of manual removal of blood followed by separation of plasma by gravity, keeping it in the bottle for a long time, has now been totally replaced by plasmapheresis, centrifugation, membrane filtration, and immunoadsorption techniques. The indications for use have also changed from a list of limited indications in the beginning to include all immune complex disorders. The clinical beneficiaries have also increased from blood bankers to nephrologists and immunologists in addition to oncologists. Efforts are now underway with the help of the Indian Society for Apheresis (founded in 1985) to popularize the newer methods of cryofiltration, photopheresis and heparin extracorporeal low-density lipoprotein (HELP) and DALI apheresis systems besides the specialized techniques of immunoadsorption using filters, columns, or ligands. This is suggestive of a positive trend for the treatment of immune complex disorders.  相似文献   
999.
1000.
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