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   6366篇
  免费   424篇
  国内免费   30篇
耳鼻咽喉   54篇
儿科学   130篇
妇产科学   96篇
基础医学   625篇
口腔科学   120篇
临床医学   688篇
内科学   1354篇
皮肤病学   45篇
神经病学   484篇
特种医学   569篇
外科学   982篇
综合类   100篇
一般理论   2篇
预防医学   661篇
眼科学   87篇
药学   361篇
  1篇
中国医学   3篇
肿瘤学   458篇
  2022年   41篇
  2021年   84篇
  2020年   53篇
  2019年   83篇
  2018年   122篇
  2017年   75篇
  2016年   80篇
  2015年   102篇
  2014年   136篇
  2013年   211篇
  2012年   352篇
  2011年   323篇
  2010年   176篇
  2009年   162篇
  2008年   276篇
  2007年   310篇
  2006年   277篇
  2005年   271篇
  2004年   269篇
  2003年   212篇
  2002年   206篇
  2001年   182篇
  2000年   193篇
  1999年   170篇
  1998年   77篇
  1997年   64篇
  1996年   76篇
  1995年   64篇
  1994年   68篇
  1993年   62篇
  1992年   158篇
  1991年   135篇
  1990年   164篇
  1989年   158篇
  1988年   144篇
  1987年   143篇
  1986年   136篇
  1985年   102篇
  1984年   91篇
  1983年   74篇
  1982年   44篇
  1981年   39篇
  1980年   43篇
  1979年   55篇
  1978年   59篇
  1977年   40篇
  1976年   48篇
  1974年   52篇
  1973年   46篇
  1972年   44篇
排序方式: 共有6820条查询结果,搜索用时 15 毫秒
41.
42.
The purpose of this study was to better understand the molecular composition of the cochlea. Fibronectin (FN), a well characterized adhesive glycoprotein, was localized by immunofluorescence microscopy in fresh and fixed cochlear tissues, and in fixed kidney tissue, using a polyclonal, affinity-purified, rabbit, anti-fibronectin antibody and a secondary antibody coupled to FITC. The FN antibody was free from cross-reactivity with other known basement membrane and cell matrix molecules. FN reactivity in the cochlea was most intense in the basilar membrane, latero-basal borders of Boettcher's cells, otic capsule, endothelial basement membranes (particularly those of the stria vascularis), and as a diffuse, fan-shaped network radiating into the spiral ligament. Little FN labelling was present in the epithelial basement membranes. Negative control tissue showed no immunoreactivity; whereas, positive kidney control tissue showed appropriate FN immunoreactivity in the mesangium of the glomerulus. The most significant finding of this study was that FN is a major component of the basilar membrane and its distribution appears to correspond to the amorphous ground substance. FN was not localized in the organ of Corti or at the tips of the hair-cell stereocilia.  相似文献   
43.
Despite improved resolution with new imaging techniques, surgical confirmation of mediastinal lymph node status is often required for reliable staging of patients with non-small cell lung cancer. Recent scintigraphic studies suggest that s.c. administration of radiolabeled antibodies can be more efficient than the i.v. route for targeting regional lymph nodes in animals and humans. To determine if this approach could be applied to the lymphatics of the lung, we injected both specific and irrelevant radiolabeled monoclonal antibodies via a flexible fiberoptic bronchoscope through the mucosa of lobar bronchi in normal dogs. The injected antibodies were expected to drain by way of local lymphatic vessels toward the central lymph nodes, in effect following the same pathway as do cells metastasizing to these nodes during early regional tumor dissemination. To accomplish this, anesthetized dogs were intubated and then coinjected with the two labeled antibodies [600 microCi/100 micrograms (total)] through a fiberoptic bronchoscope. The animals were serially imaged and then autopsied 14-36 h after injection. Individual hilar and carinal nodes contained over 1% of the injected 131I-labeled specific antibody dose and the average selectivity was 2.5:1 with respect to a coinjected irrelevant IgG. Distant organs (mesenteric lymph node, liver, spleen, bone marrow, and lung parenchyma other than the injection site) contained much less radioactivity, and those sites accumulated a greater fraction of the non-specific labeled antibody. The ratio of iodine-131 to iodine-125 counts between hilar/carinal lymph nodes and abdominal lymph nodes ranged from 15:1 to 100:1. These initial studies indicate efficient delivery of antibody to a subset of the regional nodes via pulmonary lymphatics. They suggest the feasibility of this technique which may be of use in the detection and perhaps therapy of human lung cancer metastases in regional lymph nodes.  相似文献   
44.
During the neurological work-up of a young patient with Klippel-Feil syndrome, the presence of a neuroschisis of the cervical spinal cord was detected. The patient presented with a transient and acute hemisensory loss and a Horner's syndrome of the opposite side. The unusual presentation and radiological findings in a patient with Klippel-Feil syndrome prompted this report.  相似文献   
45.
46.
A pilot study was conducted of the biological characteristics of the leukemia cells of newly diagnosed patients with poor prognosis acute myelogenous leukemia (AML). This study included measurements of the pretherapy proliferative rate of the leukemia cells in vivo, assessment of differentiation in vivo during remission induction therapy, and the level of expression of the fms, myc, and IL1β genes in pretherapy leukemia cells. Short cell cycle times were characteristic of the best prognostic category and were associated with a rapid reduction in marrow leukemia cells in cytosine arabinoside (araC)-sensitive patients. Expression of c-fms was associated with rapid reduction in marrow leukemia cells during araC therapy and with a successful treatment outcome. Expression of the IL1β gene was associated with short remissions. These studies suggest that when compared to newly diagnosed standard prognosis AML, the leukemia of poor prognosis patients is more likely to exhibit long cell cycle times, low levels of fms expression, and is less likely to be associated with myeloid differentiation during remission induction therapy. © 1993 Wiley-Liss, Inc.  相似文献   
47.
48.
This study focuses on the meaning of comfort from the perspective of immigrant Hispanic cancer patients undergoing treatment at a large Western medical center. Patients (n = 10), in 30 ethnographical interviews conducted in Spanish by a culturally sensitive interviewer identified characteristics, needs, and sources of comfort. The characteristics of comfort were: feeling integrated, functioning and normalcy, care and nurturing, security and safety, control and "comodo." Comfort needs evolved into 6 categories: nurturing, familiar environment, safety, quality of life, normalcy, and "animo." Providers of comfort, as perceived by these Hispanic patients were: self, family, health care providers, and God. The characteristics of comfort most frequently talked about by the Hispanic participants were feeling integrated and nurtured. Integrated, a seemingly complex characteristic of comfort, reflected a sense of inner peace with oneself that went beyond the physical comfort. Function and normalcy were also perceived to be important aspects of comfort. It is important to note that the Hispanic patients on occasion used culturally relevant terms, such as comodo and animo (neither of which are readily translated into English) to convey their impressions of comfort. The study demonstrates that comfort is important in illness and cancer treatment situations, and that for these Hispanic patients it also had influence from their culture.  相似文献   
49.
50.
BACKGROUND: Although soluble mediators released by basophils in tissue sites contribute to the chronic injury that occurs in hypersensitivity diseases, only limited information is available about how circulating basophils are recruited to tissues. In particular, the interaction of basophils with endothelium under conditions that mimic physiologic flow has not been explored. OBJECTIVE: We sought to identify adhesion molecules regulating the attachment of human basophils to IL-4-activated human umbilical vein endothelial cells (HUVECs) under flow conditions. METHODS: A parallel-plate flow chamber and blocking mAbs were used to define the adhesion molecules involved in the interactions of peripheral blood basophils (PBBs) and cord blood-derived basophils (CBDBs) with IL-4-activated HUVECs and with Chinese hamster ovary (CHO) cell transfectants expressing specific adhesion molecules. A fluorescent ligand specific for very late antigen 4 (VLA-4) was used to directly examine the VLA-4 affinity state of basophils. RESULTS: Flowing PBBs and CBDBs attached to activated HUVECs and to CHO cells expressing P- or E-selectin. However, only CBDBs attached to vascular cell adhesion molecule 1 (VCAM-1)-transfected CHO cells under flow conditions. The attachment of CBDBs to CHO cells was blocked by mAbs directed against E-selectin, P-selectin, and VCAM-1, whereas attachment of PBBs was blocked by E-selectin and P-selectin mAbs. Activating VLA-4 with Mn(2+) on PBBs resulted in adhesion to the VCAM-1-transfected CHO cells, indicating that VLA-4 activity on PBBs can be regulated, at least in part, through affinity changes. The Mn(2+)-induced upregulation of basophil VLA-4 affinity was demonstrated directly by using a fluorescent ligand for VLA-4 and flow cytometry. CONCLUSIONS: The interaction of human CBDBs and PBBs with endothelium under flow conditions is mediated in part by both P- and E-selectin. VLA-4 additionally contributes to the adhesion of flowing CBDBs. However, the affinity of VLA-4 is too low to support the adhesion under flow conditions of unstimulated PBBs.  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