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   3221篇
  免费   136篇
  国内免费   13篇
耳鼻咽喉   29篇
儿科学   44篇
妇产科学   7篇
基础医学   479篇
口腔科学   106篇
临床医学   232篇
内科学   785篇
皮肤病学   46篇
神经病学   246篇
特种医学   74篇
外科学   446篇
综合类   3篇
预防医学   109篇
眼科学   93篇
药学   173篇
中国医学   4篇
肿瘤学   494篇
  2023年   13篇
  2022年   37篇
  2021年   73篇
  2020年   27篇
  2019年   44篇
  2018年   74篇
  2017年   69篇
  2016年   64篇
  2015年   68篇
  2014年   86篇
  2013年   100篇
  2012年   187篇
  2011年   179篇
  2010年   100篇
  2009年   108篇
  2008年   157篇
  2007年   154篇
  2006年   162篇
  2005年   174篇
  2004年   158篇
  2003年   147篇
  2002年   160篇
  2001年   79篇
  2000年   82篇
  1999年   82篇
  1998年   43篇
  1997年   46篇
  1996年   42篇
  1995年   29篇
  1994年   34篇
  1993年   26篇
  1992年   61篇
  1991年   65篇
  1990年   41篇
  1989年   44篇
  1988年   50篇
  1987年   31篇
  1986年   24篇
  1985年   48篇
  1984年   17篇
  1983年   16篇
  1981年   17篇
  1979年   11篇
  1978年   11篇
  1977年   10篇
  1975年   11篇
  1974年   16篇
  1972年   15篇
  1971年   13篇
  1969年   10篇
排序方式: 共有3370条查询结果,搜索用时 15 毫秒
61.
62.
Background and objectives: The aim was to produce HBcAg from plants more cheaply than can be done by other currently available means, and to apply such antigen to immunoassay procedures for pretransfusion testing of donor blood. Materials and methods: Transgenic Nicotiana tabacum cv. SR-1 plants expressing the human hepatitis B virus (HBV) core antigen (HBcAg) gene were generated by Agrobacterium-mediated transformation. The recombinant product, called tHBcAg, can assemble itself into a spherical particle with a diameter of 25 to 30 nm, and can maintain two antigenic determinants of HBcAg, namely HBc/α and HBc/β. Partly purified tHBcAg was used in the hemagglutinationinhibition (HI) test, as routinely used by the Japanese Blood Center, to test a panel of 524 blood units taken from HBV-positive donors. Results: In the HI test, tHBcAg showed serologic properties comparable to that from Escherichia coli, the standard antigen used in the Japanese Blood Center. Conclusions: Transgenic plants can produce reagents for serologic testing and perhaps even such medical materials as oral vaccines.  相似文献   
63.
64.
Genome-wide analyses such as DNA microarray, RNA sequencing and RNA interference-based high-throughput screening are prevalent to decipher a biological process of interest, and provide a large quantity of data to be processed. An ultimate goal for researchers must be extrapolation of their data to human diseases. We have conducted functional genome-wide screenings to elucidate molecular mechanisms of the inflammation amplifier, a NFκB/STAT3-dependent machinery that potently drives recruitment of immune cells to promote inflammation. Using a public database of genome-wide association studies (GWAS), we recently reported the reverse-direction method by which our mass screening data were successfully linked to many human diseases. As an example, the epiregulin–epidermal growth factor receptor pathway was identified as a regulator of the inflammation amplifier, and associated with human diseases by GWAS. In fact, serum epiregulin levels were higher in patients with chronic inflammatory disorders. The reverse-direction method can be a useful tool to narrow mass data down to focus on human disease-related genes.  相似文献   
65.
Salivary glands repair and regenerate following various types of injuries and surgical procedures. However, the tissue responses induced in the contralateral glands have yet to be elucidated in detail. Hsp27, a member of the heat-shock protein (Hsp) family, is strongly expressed in physiological environments, particularly during development. Hsp27 was previously shown to play a role in the regulation of acinar cell proliferation and differentiation in the rat submandibular gland.The present study performed the following surgical treatments on the right submandibular glands of adult rats: 1) duct ligation followed by unligation after one week; 2) partial sialoadenectomy; and 3) total sialoadenectomy. Immunohistochemistry for Hsp27 and Ki67 was performed in the experimental and normal contralateral glands, and localization was histologically and morphometrically analyzed.The results obtained revealed the localization of Hsp27 to the intercalated duct in the submandibular glands of non-treated rats. The expression of Hsp27 was strongly induced in both the uninjured contralateral control glands as well as treated glands of experimental rats regardless of the surgical procedure performed. The number of Hsp27-immunopositive cells increased rapidly following surgery, and subsequently returned to the same level as that in non-treated rats after 4 weeks. However, no marked changes were observed in the number of Ki67-immunopositive proliferating cells. Therefore, the change in the number of Hsp27-immunopositive cells may have contributed to compensatory hypertrophy. The results of the present study indicate that the expression of Hsp27 in the intercalated duct in the submandibular gland may play a role in the differentiation of acinar cells.  相似文献   
66.
Biliary adenofibroma (BAF) is a rare, benign liver tumor. Herein, we report a case of BAF with histological features of imminent malignant changes. Ultrasound and CT revealed a solid 2.5-cm mass in the right liver lobe. The patient was asymptomatic and had no past medical history including liver disease. A general examination that included the abdomen and the laboratory data were normal. Because of the increase of its size, this tumor was surgically resected. Grossly, a 3.5-cm nodular mass abutted on the hepatic capsule was found, and its cut surface showed a well-circumscribed, whitish, and firm lesion that showed microcystic changes in the periphery and solid changes in the central parts. Histologically, the tumor showed a proliferation of tubulocystic structures embedded in a fibrous stroma. Microcysts were prevalent in the periphery, while tubular components with abundant fibrous stroma were in the central parts. The tubules were variably dilated and branched. This case closely resembled the previously reported cases of BAF, except that there were complicated papillary projections with fine fibrovascular cores in some of the microcysts and that the epithelial component in papillary projections showed dysplastic changes and increased cellular proliferative activities, implicating ominous features of imminent malignant changes. These dysplastic and papillary changes may be an intermediate lesion leading to malignancy, which have occasionally been reported in BAF.  相似文献   
67.
68.
69.
70.
Primary strumal carcinoid tumor of the ovary (SCTO) is an extremely rare entity, though the survival rate is excellent if the disease is confined to one ovary. A case is presented here in which intraoperative squash smears in a 45‐year‐old woman with a left adnexal mass revealed dispersed or small clusters of neoplastic cells forming loosely cohesive gland‐like structures with abundant cytoplasm. The nuclear chromatin was finely granular with a “salt and pepper” appearance and occasional tiny nucleoli. The position of the nucleus presented a vaguely plasmacytoid appearance. Small fragments of thyroidal colloid‐like structures were also identified. A cytopathologic diagnosis of a SCTO was suggested. Further evaluation and immunohistochemical studies were conducted on formalin‐fixed, paraffin‐embedded material. Cords or nests of uniform cells with abundant cytoplasm, and eccentric nuclei with coarse chromatin and occasional colloidal tissue were identified on H&E sections. The tumor cells showed diffuse and strong cytoplasmic staining for chromogranin A, synaptophysin, CD56, and vimentin but were negative for calretinin, α‐inhibin or CDX2. The proliferative index with MIB‐1 was around 3%. Thyroidal colloid‐like structures were immunoreactive for thyroglobulin and TTF‐1 stains. The diagnosis of primary SCTO was confirmed based on cytopathologic, histopathological, and immunohistochemical results, and the location of the tumor. Awareness of the cytopathological findings of SCTO can assist in diagnosing this rare entity correctly. Diagn. Cytopathol. 2013;41:812–816. © 2011 Wiley Periodicals, Inc.  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