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   4758篇
  免费   392篇
  国内免费   16篇
耳鼻咽喉   84篇
儿科学   138篇
妇产科学   49篇
基础医学   688篇
口腔科学   73篇
临床医学   558篇
内科学   831篇
皮肤病学   104篇
神经病学   526篇
特种医学   243篇
外国民族医学   1篇
外科学   729篇
综合类   28篇
一般理论   2篇
预防医学   350篇
眼科学   107篇
药学   335篇
中国医学   5篇
肿瘤学   315篇
  2023年   67篇
  2022年   90篇
  2021年   244篇
  2020年   147篇
  2019年   213篇
  2018年   241篇
  2017年   170篇
  2016年   169篇
  2015年   201篇
  2014年   242篇
  2013年   280篇
  2012年   372篇
  2011年   359篇
  2010年   209篇
  2009年   174篇
  2008年   233篇
  2007年   222篇
  2006年   185篇
  2005年   123篇
  2004年   135篇
  2003年   95篇
  2002年   79篇
  2001年   29篇
  2000年   28篇
  1999年   29篇
  1998年   37篇
  1997年   41篇
  1996年   47篇
  1995年   38篇
  1994年   36篇
  1993年   21篇
  1992年   32篇
  1991年   50篇
  1990年   28篇
  1989年   45篇
  1988年   50篇
  1987年   43篇
  1986年   37篇
  1985年   48篇
  1984年   31篇
  1983年   19篇
  1982年   24篇
  1981年   21篇
  1980年   15篇
  1979年   17篇
  1978年   14篇
  1977年   10篇
  1976年   12篇
  1975年   13篇
  1974年   11篇
排序方式: 共有5166条查询结果,搜索用时 234 毫秒
991.
Cryoablation is a safe and effective nonsurgical treatment for breast fibroadenomas (FAs). The treatment response is inversely related to the tumor size, with lesions less than 2 cm showing an optimal response. Ultrasound (US) imaging follow‐up of the ablated tumor is recommended at 6‐month intervals for 2 years at our institution. Although a decrease in the size of the FA clinically and on US imaging is the expected treatment response, variations can be seen. Knowledge of typical US changes over time is imperative to prevent unnecessary rebiopsy or excision in patients who have undergone cryoablation. We will review the initial patient selection criteria, cryoablation technique, and US findings at regular follow‐up intervals after cryoablation of FAs through a series of cases treated at our institution.  相似文献   
992.
The sheep analogue of leucocyte common antigen (LCA).   总被引:2,自引:0,他引:2       下载免费PDF全文
J F Maddox  C R Mackay    M R Brandon 《Immunology》1985,55(2):347-353
The tissue distribution and immunochemical properties of antigens recognized by two monoclonal antibodies 1.11.32 and 1.28.124 define the sheep analogue of the leucocyte common antigen found in rat, man and mouse. Histological and immunofluorescent studies show that this antigen is found on all lymphocytes, as well as other leucocytes but is absent from non-leucocytic cells. Immunochemical data show that a series of proteins of high molecular weight (190,000-225,000) are recognized, and histological studies show the presence of this antigen on a subpopulation of fetal liver cells as early as Day 27-30 of gestation, and on all fetal thymocytes from Day 40 of gestation.  相似文献   
993.
Fifty-one pediatric patients who were suspected of having central nervous system (CNS) tumors underwent magnetic resonance (MR) imaging using a 0.35 T Diasonics MT/S system. Pulse intervals (TR) ranged from 0.5 to 2.0 seconds with echo delays (TE) of 28 and 56 msec. The ability of MR and contrast-enhanced CT to detect focal lesions, determine lesion extent, and evaluate associated abnormalities was compared. In most patients in whom there was suspected spinal cord disease, comparison with myelography was made. Thirty-three intracranial lesions were detected with at least one imaging modality in 43 cranial examinations. MR was judged superior to CT in 14 of these cases and CT superior to MR in only one. Of eight spinal examinations, there were six that demonstrated abnormal findings. MR was superior to CT in all six cases and better than myelography in four of five cases where myelography was performed. Spin echo (SE) sequences with long pulse intervals were the most sensitive, but in some cases short pulse intervals permitted further characterization of the lesion. Patient motion was not a problem; sedation was routinely used in children younger than five years of age. MR imaging has rapidly become a valuable diagnostic modality in neuroradiology. The lack of ionizing radiation and the ability to evaluate the spinal cord noninvasively makes it particularly attractive in examination of children.  相似文献   
994.
Ocular and orbital lesions: surface coil MR imaging   总被引:1,自引:0,他引:1  
Nine lesions, four ocular (three melanomas, one hemangioma) and five orbital (two perioptic meningiomas, one hemangioma, one pseudotumor, one mucocele), were evaluated by magnetic resonance surface coil imaging at 1.5 T. Small ocular lesions with 3.9-4.5-mm-elevation were demonstrated. The use of two different pulse sequences resulted in separation of melanoma from adjacent retinal detachment. Contrast obtained between orbital lesions and the adjacent normal structures was better than that demonstrated with high-resolution computed tomography.  相似文献   
995.
996.
Integration of bovine leukaemia virus in the ovine genome   总被引:1,自引:0,他引:1  
Circulating lymphocytes and tumour cells from 12 sheep experimentally infected with bovine leukaemia virus (BLV), for periods of time varying from 9 to 48 weeks, were analysed for evidence of integrated and unintegrated provirus. Hybridization analysis demonstrated that the provirus was integrated at one or two sites in all cases. Integration was observed at different sites in the animals studied and there was no evidence of unintegrated virus molecules in infected sheep lymphocytes or tumour cells. The data obtained support a monoclonal origin of different tumours in the same sheep.  相似文献   
997.
Pituitary adenomas: high-resolution MR imaging at 1.5 T   总被引:3,自引:0,他引:3  
Kucharczyk  W; Davis  DO; Kelly  WM; Sze  G; Norman  D; Newton  TH 《Radiology》1986,161(3):761-765
The magnetic resonance (MR) images of 28 patients with surgically confirmed pituitary adenomas were retrospectively evaluated. The examinations were performed on a 1.5-T superconducting MR system using a multisection spin-echo technique with 3-mm-thick sections and a 256 X 256 matrix. T1- and T2-weighted images were obtained in sagittal and coronal planes. The MR findings were correlated with detailed operative reports and diagrams. There were 11 microadenomas and 17 macroadenomas. Ten of the microadenomas and all of the macroadenomas were accurately localized and their extent delineated, particularly on T1-weighted coronal sections. Adenomas typically appeared hypointense on T1-weighted coronal sections. The appearance on T2-weighted images was variable, and generally the lesions were less well seen. Involvement of parasellar structures, particularly the optic chiasm and cavernous sinuses, was accurately depicted. Cyst formation and hemorrhage could be characterized in some instances. In general, there was excellent correlation between MR imaging and operative findings.  相似文献   
998.
999.
The surface phenotypes (CD1, CD4, CD5, CD8, SBU-T19, MHC class I, MHC class II, and sIg) of cells in blood, lymph nodes, and lymph were determined to examine simultaneously the distribution of lymphocyte subsets circulating in blood, afferent lymph, and efferent lymph of a peripheral lymph node. Marked differences in the percentage of certain lymphocyte subsets were apparent within the compartments examined, suggesting that lymphocyte subsets leave the blood with differing efficiencies. Lymphocyte subsets also appeared to be extracted from the blood at different rates by lymph node as opposed to subcutaneous vascular endothelium. Endothelial cells in different vascular beds may express different numbers of molecules complementary to a set of migration-related cell surface molecules specific for each lymphocyte subset. Accordingly, the vascular endothelium would be the key factor in regulating nonrandom cell migration.  相似文献   
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