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   2142篇
  免费   111篇
  国内免费   15篇
耳鼻咽喉   8篇
儿科学   49篇
妇产科学   16篇
基础医学   300篇
口腔科学   51篇
临床医学   122篇
内科学   547篇
皮肤病学   27篇
神经病学   245篇
特种医学   73篇
外科学   370篇
综合类   7篇
预防医学   42篇
眼科学   17篇
药学   172篇
中国医学   3篇
肿瘤学   219篇
  2023年   16篇
  2022年   10篇
  2021年   70篇
  2020年   30篇
  2019年   43篇
  2018年   55篇
  2017年   47篇
  2016年   50篇
  2015年   52篇
  2014年   72篇
  2013年   78篇
  2012年   124篇
  2011年   173篇
  2010年   95篇
  2009年   61篇
  2008年   109篇
  2007年   141篇
  2006年   147篇
  2005年   126篇
  2004年   156篇
  2003年   115篇
  2002年   117篇
  2001年   10篇
  2000年   27篇
  1999年   36篇
  1998年   30篇
  1997年   21篇
  1996年   26篇
  1995年   17篇
  1994年   23篇
  1993年   32篇
  1992年   17篇
  1991年   17篇
  1990年   22篇
  1989年   19篇
  1988年   11篇
  1987年   9篇
  1986年   13篇
  1985年   5篇
  1984年   7篇
  1983年   7篇
  1982年   6篇
  1981年   2篇
  1980年   5篇
  1979年   2篇
  1977年   2篇
  1975年   2篇
  1968年   3篇
  1966年   2篇
  1955年   1篇
排序方式: 共有2268条查询结果,搜索用时 226 毫秒
101.
Splenectomy is an effective technique in living donor liver transplantation (LDLT) with small‐for‐size (SFS) liver grafts for overcoming SFS liver graft injury. However, the protective mechanism of splenectomy is still unclear. The aim of this study was to investigate how splenectomy could attenuate SFS graft injury through the measurement of biochemical factors, particularly the expression of endothelin (ET)‐1, which is a key molecule of microcirculatory disorders by mediating sinusoidal vasoconstriction. We performed rat orthotopic liver transplantation using SFS liver grafts with or without splenectomy. We investigated intragraft expression of ET‐1 mRNA and hepatic protein levels of ET‐1. In addition, portal pressure, hepatic injury and morphological changes, and survival rate were evaluated. In result, intragraft ET‐1 mRNA expression after SFS liver transplantation was significantly downregulated by splenectomy, and hepatic expression of ET‐1 in SFS grafts was rarely observed. Splenectomy inhibited the increase in portal pressure, ameliorated SFS liver graft injury and improved the graft survival rate after SFS liver transplantation. In conclusion, splenectomy improved the SFS liver injury and decreased the expression of ET‐1 by attenuating portal hypertension on SFS liver transplantation. Downregulation of intragraft ET‐1 expression plays important roles in the protective mechanism of splenectomy in SFS liver transplantation.  相似文献   
102.
103.
In vitro antigen stimulation of peripheral blood mononuclear cells (PBMCs) does not induce immunoglobulin (Ig) production. However, pretreatment of PBMCs with l-leucyl-l-leucine methyl ester (LLME) prior to in vitro stimulation removes the suppression of Ig production. In the present study, we attempted to identify the target cells of LLME and determine the mechanisms by which Ig production in PBMCs is suppressed. We found that CD14+ monocytes are involved in the suppression of Ig production in PBMCs. Furthermore, we confirmed that heavy-chain ferritin derived from CD14+ monocytes suppresses Ig production in PBMCs, possibly through iron sequestration.  相似文献   
104.
The ultraviolet B (UVB) component of sunlight can cause severe damage to skin cells and even induce skin cancer. Growing evidence indicates that the UVB‐induced signaling network is complex and involves diverse cellular processes. In this study, we investigated the role of c‐Jun NH2‐terminal kinase‐associated leucine zipper protein (JLP), a scaffold protein for mitogen‐activated protein kinase (MAPK) signaling cascades, in UVB‐induced apoptosis. We found that UVB‐induced skin epidermal apoptosis was prevented in Jlp knockout (KO) as well as in keratinocyte‐specific Jlp KO mice. Analysis of the repair of UVB‐induced DNA damage over time showed no evidence for the involvement of JLP in this process. In contrast, UVB‐stimulated p38 MAPK activation in the skin was impaired in both Jlp KO and keratinocyte‐specific Jlp KO mice. Moreover, topical treatment of UVB‐irradiated mouse skin with a p38 inhibitor significantly suppressed the epidermal apoptosis in wild‐type mice, but not in Jlp KO mice. Our findings suggest that JLP in skin basal keratinocytes plays an important role in UVB‐induced apoptosis by modulating p38 MAPK signaling pathways. This is the first study to show a critical role for JLP in an in vivo response to environmental stimulation.  相似文献   
105.
Neuroblastoma is a malignant tumor predominantly occurring in children and usually arising from the adrenal gland or sympathetic ganglia. We describe a neuroblastoma in a 1‐month‐old boy arising from his left orbital cavity. This tumor was refractory to chemotherapy or radiotherapy, requiring enucleation of the left eye for complete removal of the intraorbital tumor. Thereafter, he received high‐dose chemotherapy followed by autologous peripheral blood stem cell transplantation, and has been in complete remission for 3 years. Unlike neuroblastomas arising from the adrenal gland or sympathetic ganglia, primary orbital neuroblastoma may be refractory even in early infancy.  相似文献   
106.
The clinical features of patients reflux esophagitis without any symptoms have not been clearly demonstrated. This study evaluated the clinical features of patients with endoscopy-positive reflux esophagitis, who did not complain of symptoms, as detected by brief questioning by nursing staffs. Eight thousand and thirty-one patients not taking medication for gastrointestinal disease, were briefly asked about the presence of heartburn, dysphagia, odynophagia and acid regurgitation by nursing staffs before endoscopy for assessment of esophagitis utilizing the Los Angeles Classification. Endoscopically, 1199 (14.9%) patients were classified as positive for reflux esophagitis. The endoscope positive subjects who complain heartburn were 539/1199 (45.0%).The endoscope positive subjects who do not complain symptoms were 465 in 1199 positive reflux esophagitis (38.8%). We compared endoscopic positive subjects without any complain by brief question by nursing staffs to endoscopic positive subjects with heartburn. Male gender, no obesity, absence of hiatus hernia, and low-grade esophagitis were associated with endoscopy-positive patients who do not complain of symptoms. The results of this study indicated correct detection of clinical symptoms of reflux esophagitis might be not easy with brief questioning by nursing staffs before endoscopic examination.  相似文献   
107.
The methods we used to produce a carcinoma in the extrahepatic bile duct and gallbladder in hamsters are described along with the characteristics of the induced tumors. Female Syrian golden hamsters were first subjected to Cholecystoduodenostomy with dissection of the extrahepatic bile duct on the distal end of the common duct (CDDB) and were, 4 weeks later, treated with weekly subcutaneous injections of N-nitrosobis(2-oxopropyl)amine (BOP) at a dose of 10 mg/kg body weight for 9 weeks. The animals were killed at the 12th, 16th and 20th week after the initiation of BOP treatment. Extrahepatic bile duct carcinoma developed in 16%, 24% and 41% and gallbladder carcinoma occurred in 58%, 81% and 82% of the hamsters, respectively, at the corresponding times of killing. The incidences were significantly higher than those in sham-operated controls ( P <0.01). The induced extrahepatic bile duct carcinomas were predominantly of the polypoid type and gallbladder carcinomas were of the papillary type in growth form, being morphologically similar to early stage biliary carcinoma in humans. Immunohistochemical staining using bromodeoxynridine and anti-bromo-deoxyuridine monoclonal antibody demonstrated that the CDDB procedure greatly accelerated the cell kinetic activity of the biliary epithelium, and this was considered to be a major factor promoting the development of biliary carcinomas in this hamster model. In conclusion, this new model provides a high incidence of tumor development at the extrahepatic biliary tract and is expected to be useful for clarifying the characteristics of this highly malignant tumor.  相似文献   
108.
109.
Lymphokine-activated killer (LAK) cell activity of peripheral blood mono-nuclear cells (PBM), spleen cells (SPC), regional lymph node cells (LNC), and tumor-infiltrating lymphocytes (TIL), induced by activation with in-terleukin 2 (IL 2) for 4 days, was evaluated in patients with gastric carcinoma. TIL exhibited the lowest LAK activity and the cytotoxicity of LNC was significantly lower than that of either PBM or SPC. There was no difference between PBM and SPC. Then, there were significant correlations of LAK activity among PBM, SPC, and LNC, whereas poor correlations were observed in the cytotoxicity between TIL and PBM, SPC, or LNC. Phenotypic analysis of each cell population was performed before and after activation with IL 2. Before culture, the cells mediating natural killer (NK) activity such as CD16+, CD56+, and CD57+ cells were few in LNC and TIL. However, CD56+ and CD57+ cells in TIL were increased after culture. Then, CD4+ Leu8+ and CD8+ CD11+ cells, which identify suppressor cell function, were not elevated in LNC or TIL, as compared to that in PBM or SPC. Further, the proportions of OKIa1+ and CD25+ cells expressing T-cell activation and IL 2 receptor were uniformly increased in all cell populations after culture. These results indicate the differential reactivity of each lymphocyte population to IL 2 and fundamental dysfunction of LNC and, especially TIL, suggesting the specific influence of the local tumor environment on the lymphocyte function in the area in patients with gastric carcinoma. © Wiley-Liss, Inc.  相似文献   
110.
The aim of this study was to examine whether the type of bilioenterostomyenhances biliary carcinogenesis in the hamster model. Syrianhamsters were divided into the following groups; simple laparotomy(control group), cholecystoduodenostomy with dissection of theextrahepatic bile duct on the distal end of the common duct(CDDB group) and cholecystoileostomy with dissection of theextrahepatic bile duct on the distal end of the common duct(CIDB group). Following these procedures, all hamsters receivedN-nitrosobis(2-oxopropyl)amine. The diameter of the extrahepaticbile duct and plasma levels of cholecystokinin (CCK) were measuredand the number of neoplastic lesions was counted microscopically.Proliferative effect of the procedures on the biliary epitheliumwas examined by proliferative cell nuclear antigen. In the CDDBgroup the extrahepatic bile duct was significantly dilated andcarcinogenesis of the gall-bladder and extrahepatic bile ductswas enhanced. In the CIDB group the CCK bioactivity was stimulatedand intrahepatic biliary duct, but not gall bladder and extrahepaticbile duct, carcinogenesis was promoted more than that observedin the CDDB group. Proliferation of the biliary duct epitheliumwas enhanced in both the CDDB and CIDB groups. Cholecystoduodenostomyenhanced intra- and extrahepatic bile duct carcinoma, whereascholecystoileostomy promoted only intrahepatic bile duct carcinoma.Some factors in the intestinal juice seem to play a role inthe promotion of biliary tract carcinoma.  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