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   7541篇
  免费   371篇
  国内免费   51篇
耳鼻咽喉   69篇
儿科学   210篇
妇产科学   69篇
基础医学   1011篇
口腔科学   185篇
临床医学   425篇
内科学   2054篇
皮肤病学   116篇
神经病学   620篇
特种医学   320篇
外科学   1238篇
综合类   24篇
预防医学   182篇
眼科学   154篇
药学   456篇
中国医学   30篇
肿瘤学   800篇
  2023年   36篇
  2022年   85篇
  2021年   118篇
  2020年   64篇
  2019年   101篇
  2018年   99篇
  2017年   109篇
  2016年   137篇
  2015年   167篇
  2014年   188篇
  2013年   216篇
  2012年   379篇
  2011年   442篇
  2010年   229篇
  2009年   236篇
  2008年   394篇
  2007年   499篇
  2006年   439篇
  2005年   506篇
  2004年   479篇
  2003年   524篇
  2002年   477篇
  2001年   129篇
  2000年   116篇
  1999年   147篇
  1998年   148篇
  1997年   119篇
  1996年   130篇
  1995年   118篇
  1994年   96篇
  1993年   75篇
  1992年   75篇
  1991年   83篇
  1990年   65篇
  1989年   73篇
  1988年   52篇
  1987年   52篇
  1986年   51篇
  1985年   41篇
  1984年   45篇
  1983年   34篇
  1982年   34篇
  1981年   41篇
  1980年   38篇
  1979年   29篇
  1978年   37篇
  1977年   32篇
  1976年   26篇
  1975年   21篇
  1974年   24篇
排序方式: 共有7963条查询结果,搜索用时 0 毫秒
991.
992.

Purpose  

Previous studies have reported that astaxanthin (AXT) has antioxidative and anti-inflammatory effects in addition to its ability to shorten blood transit times. As laser speckle flowgraphy (LSFG) can noninvasively visualize the hemodynamics of the choroidal circulation, we used the technique to evaluate whether continuous ingestion of 12 mg of AXT per day could increase quantitative blood flow velocity.  相似文献   
993.

Background

Infliximab, an anti-TNF-α monoclonal antibody, administered to Beh?et’s disease (BD) patients in Japan with refractory intraocular inflammation, has shown excellent clinical results. However, some patients demonstrate a decreased response to infliximab during the course of the treatment. In the present study, we investigated the correlation between this reduced therapeutic effect and elevation of the serum antinuclear antibody (ANA) titers in patients with BD who were undergoing infliximab therapy.

Methods

Seventeen patients (14 males and three females) with uveitis in BD who were undergoing treatment with infliximab for 2?years or longer were enrolled. Their blood test results and clinical histories were obtained from medical records.

Results

One patient (5.9%) was ANA-positive prior to the initiation of infliximab, and 11 patients (64.7%) developed positive ANA during the therapy. The appearance of ANA was observed 6?months after the initiation of the infliximab therapy, and its titers gradually increased. None of the patients showed lupus symptoms. Five patients (29.4%) have suffered from ocular inflammatory attacks since the sixth month from the initiation of infliximab treatment and all of them were ANA-positive. In contrast, four patients (23.5%) who were ANA-negative experienced no ocular attacks during the follow-up period.

Conclusions

Here we report the positive conversion and subsequent elevation of serum ANA titers in some patients with BD after the initiation of infliximab therapy. Since all recurrences of uveitis were shown only in the ANA-positive patients, serum ANA titer may be a helpful biomarker for predicting the recurrence of ocular attacks in BD patients treated with anti-TNF-α antibody therapies.  相似文献   
994.
We developed a high-resolution fluorescence microscope in which fluorescent materials are directly excited using a focused electron beam. Electron beam excitation enables detailed observations on the nanometer scale. Real-time live-cell observation is also possible using a thin film to separate the environment under study from the vacuum region required for electron beam propagation. In this study, we demonstrated observation of cellular components by autofluorescence excited with a focused electron beam and performed dynamic observations of intracellular granules. Since autofluorescence is associated with endogenous substances in cells, this microscope can also be used to investigate the intrinsic properties of organelles.OCIS codes: (110.0180) Microscopy, (170.0180) Microscopy, (170.2520) Fluorescence microscopy, (180.2520) Fluorescence microscopy, (180.5810) Scanning microscopy  相似文献   
995.
To expand the indications for high-dose-rate interstitial brachytherapy (HDR-ISBT) for deep-seated pelvic tumors, we investigated the usefulness of Doppler transrectal ultrasonography (TRUS) guidance and virtual planning. The patient was a 36-year-old female. She had right internal iliac lymph node oligometastasis of vaginal cancer 12 months after radical radiotherapy. The tumor could not be found by gray-scale TRUS and physical examination. Virtual planning was performed using computed tomography with template and vaginal cylinder insertion. We uploaded the images to our treatment planning software and reconstructed the contours of the clinical target volume (CTV) and right internal iliac vessel. Virtual needle applicators were plotted using the template holes for virtual planning. At the time of implantation, Doppler TRUS was used to prevent vessel injury by needle applicators. Applicators were implanted in accordance with virtual planning and Doppler TRUS could detect the right iliac vessel. The percentage of CTV covered by the prescribed dose was 99.8%. The minimum dose received by the maximally irradiated 0.1-cc volume for the right internal iliac vessel was 95% prescribed dose. Complete response was achieved, however, radiological findings showed marginal recurrence at 15 months after HDR-ISBT. Post-radiation neuropathy occurred as a late complication four months after treatment; however, the pain was well controlled by medication. We consider that virtual planning and Doppler TRUS are effective methods in cases where it is difficult to detect the tumor by physical examination and gray-scale TRUS, thereby expanding the indications for ISBT.  相似文献   
996.
An 83-year-old woman presented to our echocardiographic center with symptoms of right heart failure. A dual-chamber DDDR pacemaker had been implanted 9 years earlier. Two-dimensional echocardiography revealed right atrial and ventricular enlargement and massive tricuspid regurgitation with immobilization of the anterior leaflet of the tricuspid valve. Three-dimensional transesophageal echocardiography showed that the pacemaker lead had punctured the leaflet. These echocardiographic findings were confirmed during surgery. The pacemaker lead was transected and removed, and pericardial patch closure of the leaflet hole and tricuspid annuloplasty were performed. The mechanism of regurgitation was elucidated by real-time three-dimensional echocardiography, and surgical repair was straightforward.  相似文献   
997.
Influence of luminal Ca2+ on the integrity of normal mucosa and recovery of damaged mucosa in anesthetized rat stomachs was studied using a perfusion system. Changes in the mucosal integrity were monitored by measuring transmucosal potential difference (PD) and luminal pH. EDTA, a Ca2+ chelator, dose-dependently reduced PD and increased luminal pH. Five mM Ca2+ (CaCl2) alone produced no changes in either PD and luminal pH, but the PD which was reduced by 250 mM EDTA was significantly recovered. Ethanol or NaCl concentration-dependently reduced PD, but gradually reverted to baseline levels. While 5 mM Ca2+ or 5 mM EDTA did not influence the reduction in PD with 50% ethanol or 1 M NaCl, these agents either enhanced or delayed the recovery processes in reduced PD, respectively. Five mM Ca2+ enhanced the recovery of PD which was reduced by 50% ethanol plus 5 mM EDTA. Gastric damage induced by 50% ethanol plus 5 mM EDTA was much more severe than that induced by 50% ethanol alone or 50% ethanol plus 5 mM Ca2+. Both 50% ethanol and 1 M NaCl significantly increased Ca2+ contents in the gastric lumen. Luminal Ca2+ appears to play an important role in maintaining mucosal integrity, under normal physiological conditions, and in accelerating the recovery process of damaged mucosa in rat stomachs.  相似文献   
998.
Fifty-one homozygous patients with familial hypercholesterolemia, including our six patients, are described in this paper. Twenty were men and 31 were women. Their ages ranged between two and 52 years, with a mean of 16.8 years. Six patients exceeded the third decade. The mean age at death in seven patients was 17 years. The serum cholesterol levels were between 508 and 1,108 mg/dl. The mean and standard deviation (SD) of serum cholesterol were 713 ± 142 mg/dl. The serum cholesterol levels in the 35 parents (obligate heterozygotes) were between 246 and 571 mg/dl, except in one patient in whom the serum cholesterol level (936 mg/dl) was suggestive of homozygous familial hypercholesterolemia, considering the serum cholesterol level (354 mg/dl) of her heterozygous husband. The mean and SD of serum cholesterol levels of the 34 heterozygote parents were 342 ± 79 mg/dl. The mean and SD of serum cholesterol in 119 normal subjects were 187 ± 30 mg/dl. Thus, trimodai distribution was evident in the serum cholesterol levels of normal subjects, the heterozygotes and the homozygotes in Japan. The frequency of parental consanguinity was at least 33 per cent. The frequencies of ischemic heart disease in the age groups 0–9, 10–19 and above 20 years were 25 per cent (four of 16 patients), 33 per cent (six of 18 patients) and 53 per cent (nine of 17 patients), respectively. The frequency of homozygotes in Japan was in close accordance with those of Western countries. Therefore, the treatment of hypercholesterolemia and prevention of premature coronary heart disease in familial hypercholesterolemic patients are very important problems in Japan as well as in the West.  相似文献   
999.
We investigated the role of the autonomic nervous system in gastric acid secretion, somatostatin concentration and PAS-positive mucus production in Brunner’s glands in cysteamine-induced duodenal ulcer. Vagotomized rats were used. No ulcers occurred in the groups with vagotomies of the hepatoduodenal, truncal or gastric branches after cysteamine administration. However, in the hepatoduodenal branch vagotomized group, there was an increases in gastric acid secretion after cysteamine administration. A similar increase was observed in the control group, but the decreases in somatostatin concentration and PAS-positive mucus seen in the control group were not found in the hepatoduodenal vagotomized group. These results suggest that the hepatoduodenal branch of the vagus nerve might play an important role in the ulcerogenic process of cysteamine-induced duodenal ulcer.  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