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   12460篇
  免费   526篇
  国内免费   68篇
耳鼻咽喉   138篇
儿科学   241篇
妇产科学   180篇
基础医学   1572篇
口腔科学   289篇
临床医学   674篇
内科学   2997篇
皮肤病学   244篇
神经病学   823篇
特种医学   396篇
外科学   2416篇
综合类   71篇
一般理论   1篇
预防医学   314篇
眼科学   234篇
药学   1014篇
中国医学   96篇
肿瘤学   1354篇
  2023年   74篇
  2022年   140篇
  2021年   260篇
  2020年   128篇
  2019年   180篇
  2018年   221篇
  2017年   171篇
  2016年   247篇
  2015年   232篇
  2014年   291篇
  2013年   379篇
  2012年   605篇
  2011年   627篇
  2010年   373篇
  2009年   343篇
  2008年   627篇
  2007年   669篇
  2006年   639篇
  2005年   641篇
  2004年   648篇
  2003年   720篇
  2002年   718篇
  2001年   337篇
  2000年   378篇
  1999年   345篇
  1998年   182篇
  1997年   115篇
  1996年   92篇
  1995年   97篇
  1994年   94篇
  1993年   106篇
  1992年   220篇
  1991年   178篇
  1990年   232篇
  1989年   215篇
  1988年   197篇
  1987年   192篇
  1986年   206篇
  1985年   144篇
  1984年   110篇
  1983年   80篇
  1982年   46篇
  1981年   35篇
  1980年   37篇
  1979年   74篇
  1978年   59篇
  1977年   42篇
  1974年   42篇
  1973年   33篇
  1972年   34篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Platelet-activating factor in late asthmatic response   总被引:8,自引:0,他引:8  
The role of platelet-activating factor (PAF) in the late asthmatic responses was studied. The concentrations of lyso-form of PAF in plasma were measured at 0 and 20 min, and 6 and 24 h after the antigen inhalation challenge among patients with bronchial asthma. PAF activities were measured by their aggregating ability of washed rabbit platelets after acetylation of lyso-PAF into the biological active form of PAF, when there were no detectable amounts of PAF in plasma. The concentrations of lyso-PAF were found to be significantly increased in patients with the late asthmatic response compared with patients with the single immediate response at 6 h after the antigen challenge. In contrast, lyso-PAF levels were not significantly different at 20 min after the antigen challenge between these two groups. PAF inactivator activity in plasma increased when there was a decrease in the lyso-PAF level. These results suggest that PAF may participate in the late asthmatic response and may provide a new insight into the pathogenesis and the treatment of bronchial asthma.  相似文献   
72.
We describe HLA-DRB1 typing using polymerase chain reaction-based microtitre plate hybridization (PCR-MPH), which can process large numbers of samples. MPH typing is similar to an enzyme-linked immunosorbent assay (ELISA), in which a tandemly ligated sequence-specific oligonucleotide is immobilized on microtitre wells. The typing procedure consisted of two steps. In the first, PCR-MPH with 16 probes was performed to determine the specificities of the serological levels (DR1, DR2, DR3, DR4, DR11, DR12, DR13, DR14, DR7, DR8, DR9 and DR10) after generic amplification (‘low resolution typing’). In the second step, DR1, DR2, DR4, DR 12/8 and DR3/11/13/14 were group-specifically amplified based on the results of the first PCR-MPH, and microtitre plate hybridization proceeded in a similar manner to the first step (‘high resolution typing’). Low resolution typing was completed within 2 h after generic amplification, and the results of high resolution typing were obtained in another 3.5 h after amplification. The allelic types classified using PCR-MPH were completely concordant with those obtained by PCR- single-strand conformation polymorphism or PCR-restriction fragment length polymorphism.  相似文献   
73.
74.
AIMS: To investigate the relation between localised amyloidosis and immunocytic dyscrasia. METHODS: Open lung biopsy specimens from a 72 year old man with multiple nodules in the right middle and lower lung were stained with haematoxylin-eosin, Congo red, and antibodies against IgG, IgA, IgM, and kappa and lambda light chains. Semi-nested PCR amplification for the immunoglobulin heavy chain (IgH) gene was performed using consensus primers for the VDJ region of the IgH gene, FR3A, LJH, and VLJH. RESULTS: The biopsy specimens contained eosinophilic amorphous material stained with Congro red and anti-kappa light chain, and surrounded by inflammatory cells intermingled with plasma cells. Plasma cells in the adjacent amorphous material showed cytoplasmic staining with anti-kappa. Polymerase chain reaction revealed a discrete amplified band of apparently uniform size with background smear. CONCLUSIONS: Primary AL type localised amyloidosis involves local accumulation of monoclonal plasma cells and their secreted products, as in nodular cutaneous amyloidosis. Localised AL type nodular amyloidosis is a separate entity in amyloidosis.  相似文献   
75.
76.
BACKGROUND: In Japan in 1993, the Japanese Society of Allergology (JSA) developed guidelines for diagnosis and management of asthma (JGL), which were based on the concept that asthma is a chronic inflammatory disorder of the airway. METHODS: This survey study was intended to investigate the recognition and utilization of JGL among physicians who had treated asthma. The survey comprised two methods: a quantitative mail survey and a qualitative door-to-door survey conducted by trained interviewers. RESULTS: In the mail survey, a total of 1028 physicians responded; 552 members of the JSA and 476 nonmembers. Ninety-four percent of JSA members were aware of adult asthma management guidelines, while 53% of nonmembers were aware of them. Although approximately half of the physicians, both members and nonmembers, found differences between the asthma management policies in JGL and their previous policies, most of them utilized JGL once they read it. In the qualitative door-to-door survey, 80-90% of physicians evaluated JGL as good after they read it. CONCLUSIONS: JGL was recognized and utilized by most JSA members, but only half of nonmember physicians were aware of JGL, although they utilized JGL after they read it. Further action to implement JGL among nonspecialist physicians is needed to improve management of asthma.  相似文献   
77.
78.
AIMS: We investigated a rare case of small vessel vasculitis (SVV) limited to pleuropulmonary manifestations, possibly induced by endotoxin, to determine the activation of immuno-mediated cells and endothelia in the pleuropulmonary circulation. METHODS AND RESULTS: A 44-year-old man with a high fever was X-rayed, revealing bilateral pleural effusion and atelectasis in the chest. His laboratory data were within normal limits except for a high white blood cell count and a high C-reactive protein level. Autoantibodies including anti-neutrophil cytoplasmic antibody were negative. Endotoxin was detected in his sera, but repeated cultures of sputa, urine, blood and the pleural effusion were negative for bacteria. Video-assisted thoracic surgery was performed and lung and parietal pleura specimens were obtained. Histology showed arterioles or small arteries infiltrated by monocytes or neutrophils with fibrinoid necrosis and acute or chronic venulitis. A diagnosis of SVV in the lung and pleura was made. Immunohistochemistry revealed that interleukin (IL)-1beta was expressed in monocytes and vascular cell adhesion molecule (VCAM)-1 on endothelial cells in the vasculitic lesions in the lung. CONCLUSIONS: Endotoxin possibly induced the inflammation in this apparently unique case of pleuropulmonary small vessel vasculitis. Immunohistochemistry revealed the expression of IL-1beta and VCAM-1 which may have caused activation of monocytes and endothelial cells within the vasculitic lesions.  相似文献   
79.
The effectiveness of the clinical pathway for laparoscopic cholecystectomy was evaluated, and the efficiency of medical care was analyzed. The duration of hospitalization and the number of National Health Insurance (NHI) points for medical service fees were compared between 86 patients treated after introduction of the clinical pathway (pathway group) and 56 patients treated before introduction of the clinical pathway (pre-pathway group). In the pathway group, variance from the pathway occurred in 24 patients (27.9%) due to postponement of discharge in 7 patients, to earlier discharge in 5 patients, and to insertion of a bile duct catheter in 5 patients. Total and postoperative hospitalization times were significantly shorter in the pathway group than in the pre-pathway group (8.0 +/- 1.6 vs 13.7 +/- 9.0 days, p<0.0001, 5.4 +/- 1.1 vs 6.5 +/- 2.2 days, p<0.0001, respectively). In the pathway group, the total number of NHI points was lower and the number of points per day was higher. By simulation, the total number of NHI points for the 5-day pathway (discharge on postoperative day 3 or earlier) was significantly lower than that for the current 7-day pathway. Moreover, the weekly profit per bed with the 3-day pathway (discharge on postoperative day 1) was more than twice that with the current pathway. The results suggest that the clinical pathway for laparoscopic cholecystectomy is beneficial for patients and useful for the introduction of diagnosis procedure combination in our hospital.  相似文献   
80.
The method of electrical impedance measurement was tested for its usefulness in monitoring of extra-cellular fluid (ECF) in the dog submandibular gland during salivary secretion. Measurements were performed during rest and stimulated state with or without blood supply. During stimulation with blood supply, the conductivities of the gland decreased to some extent. During stimulation without blood supply, the decrease in conductivities was markedly enhanced. The decrease of ECF compartment during stimulation without blood supply was ascertained by the stereological measurement. Coincidence of conductivity decrease and histologically observed decrease of ECF compartment supports the usefulness of impedance measurement for monitoring of ECF during secretory activity of gland tissue. The present study also shows that the interlobular space decreased mainly during stimulation when blood supply is absent. This indicates that, among ECF space, the interlobular space plays an important role as a fluid reservoir in the salivary gland.  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