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   3417篇
  免费   154篇
  国内免费   17篇
耳鼻咽喉   50篇
儿科学   58篇
妇产科学   13篇
基础医学   430篇
口腔科学   58篇
临床医学   204篇
内科学   847篇
皮肤病学   15篇
神经病学   144篇
特种医学   103篇
外科学   699篇
综合类   11篇
预防医学   113篇
眼科学   201篇
药学   201篇
中国医学   8篇
肿瘤学   433篇
  2023年   23篇
  2022年   23篇
  2021年   77篇
  2020年   27篇
  2019年   62篇
  2018年   73篇
  2017年   43篇
  2016年   54篇
  2015年   71篇
  2014年   82篇
  2013年   116篇
  2012年   159篇
  2011年   196篇
  2010年   113篇
  2009年   99篇
  2008年   186篇
  2007年   198篇
  2006年   191篇
  2005年   230篇
  2004年   191篇
  2003年   176篇
  2002年   171篇
  2001年   58篇
  2000年   78篇
  1999年   80篇
  1998年   35篇
  1997年   25篇
  1996年   19篇
  1995年   26篇
  1994年   15篇
  1992年   51篇
  1991年   42篇
  1990年   34篇
  1989年   43篇
  1988年   40篇
  1987年   40篇
  1986年   41篇
  1985年   37篇
  1984年   24篇
  1983年   20篇
  1982年   22篇
  1981年   20篇
  1979年   24篇
  1978年   16篇
  1977年   23篇
  1975年   39篇
  1973年   15篇
  1972年   26篇
  1967年   16篇
  1966年   16篇
排序方式: 共有3588条查询结果,搜索用时 187 毫秒
1.
Antisera have been made to synthetic peptides that correspond to eight different regions of the alpha A molecule. Together with a solid phase radioimmunoassay, these antisera have been used to quantitatively assess binding to enriched alpha crystallin preparations from six different cataractous and six different normal lenses. Seven of the eight antisera show no difference in binding to alpha crystallin from cataractous versus normal lenses, whereas the antiserum directed against the alpha A sequence 120-130 shows a statistically significant decrease in binding to the alpha crystallin from cataractous lenses. Together, these studies demonstrate the feasibility of using antipeptide sera as probes of polypeptide changes during cataractogenesis and suggest that the region of the alpha A crystallin molecule encompassing residues 120-300 may undergo covalent and/or noncovalent structural modification during the process of opacification in the human senile lens.  相似文献   
2.
Using (3)H- and (125)I-labeled desmethylimipramine (DMI) for regional flow tracers, we established a two-time measurement method for the spatial pattern of myocardial perfusion in cross-circulated rat hearts. Myocardial extractions and retentions of these tracers were confirmed to be satisfactory; however, the latter were less than 90% after 3 min at a perfusion rate of 2.9 ml/min/g, limiting the present application to a short-time perfusion measurement. Distributions of myocardial depositions were separated by subtraction digital radiography with 400-microm pixel resolution. Its feasibility was examined by regression analysis between local deposition densities of (3)H- and (125)I-DMI injected simultaneously. The slope, y-intercept, and correlation coefficient (r) of the regression line were 0.98+/-0.04, 0.02+/-0.04, and 0.95+/-0.03, respectively, indicating the validity of the present image subtraction technique. The spatial pattern of myocardial perfusion in response to flow reduction was evaluated by the injections of (3)H- and (125)I-DMI, respectively, before and after a nearly 70% flow reduction. A significant correlation between normalized density distributions of these tracers was found in both subepicardium (r=0.77+/-0.12) and subendocardium (r=0.73+/-0.20), indicating the stable pattern of myocardial perfusion. However, the coefficient of variation of tracer densities showed a decrease of subendocardial flow heterogeneity from 35+/-15% to 31+/-16%. Thus, flow differences between originally high- and low-flow regions in subendocardium were reduced on a relative basis during low perfusion.  相似文献   
3.
A 22-year-old man was urgently admitted for pneumothorax. He continued complaining of exertional dyspnea and dry cough after the pneumothorax healed. About three months later, an atypical pulmonary mycobacteriosis by mycobacterium kansasii was identified. Exertional dyspnea increased after chemotherapy was administered, and the patient was readmitted because of difficulty in daily life activities. Chest radiographs and CT scans showed bilateral pulmonary hyperinflation and a narrowed heart shadow. There was also marked combined ventilatory impairment, as identified by a respiratory function test. Furthermore, the histological findings of surgically removed lung tissue revealed accumulation of lymphocytes in the wall of a small bronchus. Idiopathic bronchiolitis obliterans was diagnosed from the clinical course and clinical findings. The patient is now being monitored and is awaiting lung transplantation.  相似文献   
4.
T Takemoto  H Yanai 《Gan no rinsho》1986,32(10):1077-1081
It is obvious that surgical resection is a superior therapy for gastric cancer. In this sense, endoscopic therapy could be regarded as an orphan in this field. However, in the combination of endoscopic therapy and ultrasonic endoscopy, endoscopic therapy for gastric cancer should be acknowledged to be equal to surgical therapy. We have treated early gastric cancer by means of endoscopical photocoagulation using a Nd-YAG laser, particularly in inoperable cases due to other complication or old age. Forty-seven lesions found in 41 patients have so far been photocoagulation and followed up. By this treatment, cancer cells disappeared in 42 out of 47 lesions, although 2 cases died of other diseases and recurrence was experienced in 3 cases. In addition to photocoagulation therapy using a laser, we have recently developed a large-biopsy technique called strip biopsy in order to get sufficient tissue for diagnosis in comparison with bite biopsy. By this method, we are able to resect the full thickness of the mucosa including the submucosal layer up to a size of about 4 cm, without any severe complication such as hemorrhage and perforation. We succeeded in resecting the early gastric cancer in 34 lesion in 31 patients. The combination therapy of endoscopical photocoagulation and strip biopsy seems to be reasonable for the therapy of early gastric cancer.  相似文献   
5.
6.
7.
We have investigated the effects of short-contact topical application of tretinoin using 16 male db/db mice by creating two full-thickness wounds on the skin of the back. A 0.1% tretinoin aqueous gel was applied to one wound for five minutes daily for five successive days while only aqueous gel was applied to the other (control). The mean (SD) percentage surface area unhealed before and after treatment were 0.88 (0.3) and 0.64 (0.15). In tretinoin-treated mice and non-treated mice (controls), the mean (SD) thicknesses of granulation were 1.383 (697) micro m and 683 (413) micro m, the density of capillary vessels in granulation was 12.2 (5.5)% and 5.7 (3.9)%, respectively. Differences between the two groups were significant for each variable. Wound healing was accelerated with short-contact topical application of tretinoin in db/db mice.  相似文献   
8.
We measured serum thymidine kinase (TK) activity with a radioenzyme assay system employing [I-125]-iododeoxyuridine as the tracer on serial specimens from five bone marrow transplant (BMT) patients before and after transplantation. The serum level of TK activity in the 4 patients with effective BMT treatment ranged from 3.0 to 16.9 U/L (mean, 7.80 U/L) before transplantation and from 27.3 to 236.1 U/L (mean, 82.95 U/L) after the BMT treatment. Mean serum TK activity increased 13.17-fold (range, 1.68 to 29.14-fold). In contrast, the activity in the patient with ineffective BMT treatment was not significantly different during, before, or after BMT treatment. In addition, serum TK activity in BMT patients was well correlated with the change in the number of leukocytes before and after BMT treatment [r = +0.709 (p less than 0.01), y = 0.012 x +0.87]. We conclude that the determination of serum TK activity in BMT patients is very useful in monitoring the course of bone marrow transplantation in the early recovery phase.  相似文献   
9.
10.
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