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   45675篇
  免费   2140篇
  国内免费   211篇
耳鼻咽喉   381篇
儿科学   867篇
妇产科学   715篇
基础医学   5994篇
口腔科学   1158篇
临床医学   2922篇
内科学   11513篇
皮肤病学   734篇
神经病学   3221篇
特种医学   1602篇
外科学   8351篇
综合类   198篇
预防医学   1428篇
眼科学   499篇
药学   3276篇
中国医学   152篇
肿瘤学   5015篇
  2023年   211篇
  2022年   415篇
  2021年   770篇
  2020年   458篇
  2019年   628篇
  2018年   773篇
  2017年   615篇
  2016年   715篇
  2015年   790篇
  2014年   1058篇
  2013年   1288篇
  2012年   2057篇
  2011年   2199篇
  2010年   1228篇
  2009年   1014篇
  2008年   1982篇
  2007年   2123篇
  2006年   2169篇
  2005年   2225篇
  2004年   2192篇
  2003年   2070篇
  2002年   2098篇
  2001年   1742篇
  2000年   1674篇
  1999年   1609篇
  1998年   679篇
  1997年   537篇
  1996年   475篇
  1995年   409篇
  1994年   394篇
  1993年   363篇
  1992年   1039篇
  1991年   984篇
  1990年   854篇
  1989年   941篇
  1988年   806篇
  1987年   735篇
  1986年   763篇
  1985年   703篇
  1984年   454篇
  1983年   392篇
  1982年   212篇
  1981年   214篇
  1979年   324篇
  1978年   256篇
  1977年   219篇
  1975年   228篇
  1974年   197篇
  1973年   189篇
  1971年   183篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Single photon emission computerized tomography (SPECT) is now widely used as one of the tools in evaluating cerebral blood flow (CBF). The authors report the CBF changes in childhood hydrocephalus. Five pediatric cases studied by 123I-IM SPECT in children are presented. The authors counted radioactivities both in early and delayed images in each patient, and calculated the reabsorption ratio (RR). Two negative-RR cases and three positive-RR cases were found. All of the negative-RR patients had a poor prognosis, while all of the positive-RR patients had a favorable outcome.  相似文献   
102.
Bone scintigraphy was performed in 17 patients with previously known lung metastases of osteosarcoma. 99Tcm-MDP uptake was observed in all primary bone lesions but lung metastatic lesions were positive in only six patients (35%). 99Tcm-MDP uptake by lung metastases was significantly correlated with bone and osteoid formation in the metastatic lesions and preoperative serum ALPase values. These clinical observations were confirmed by using nude mice transplanted with human lung metastatic osteosarcoma. 99Tcm-MDP scintigraphy appears to be useful for detecting lung metastases of osteosarcoma only in a selected group of patients.  相似文献   
103.
In order to study the changes of lipid metabolism in acute pancreatitis, the following experiments were performed in monogrel dogs. Bile-induced pancreatitis (severe type) and collagenase-induced pancreatitis (mild type) were prepared, and changes of FFA, TG, IRI and IRG were determined for one week. In addition, IVFTT and PHLA were determined at 24th hour, on the 3rd day and 7th day. A rise of FFA was observed during the first 24 hours, which was considered the lypolytic stage. On the 3rd day TG reached the maximal level, while K values in IVFTT and PHLA showed the lowest levels. The above results suggest that the elimination mechanism of TG was impaired on the 3rd day. Changes of FFA, TG, IRI and IRG showed marked differences between the two groups. Therefore it is thought that lipid metabolism in acute pancreatitis is regulated by balance of endogenous pancreatic hormones.  相似文献   
104.
A 47-year-old male visited our hospital complaining of painless swelling of the right scrotum. Ultrasonography demonstrated hydrocele and a 13 x 12 x 10 mm cystic space along the margin of the right testis. Hydrocelectomy and simple resection of the cyst were performed. Pathologic examination of the excised cyst showed a serous cyst lined with simple flattened epithelium. Ultrasonography is useful for the diagnosis of tunica albuginea cyst.  相似文献   
105.
The effects of dietary protein restriction on skeletal muscle fibers were studied according to morphological and biochemical approaches. Protein and DNA content of quadriceps muscles from young adult rats were decreased by the low protein and protein-free diet. Morphological examination demonstrated that there was a significant decrease in the size of muscle fibers without change in their numbers due to protein restriction. The protein/DNA ratio, accepted as an index of cell size in biochemical approaches, was compared with cell size on photomicrographs. Actual fiber size appeared much smaller than that indicated by the protein/DNA ratio.  相似文献   
106.
N Tanaka  T Tanaka 《Journal of UOEH》1992,14(4):289-296
The analysis of blood Esterase D (ESD) phenotypes was performed by using high performance liquid chromatography (HPLC). The hemolysate was first treated with a cation exchanger to remove hemoglobin, injected into HPLC on a weak anion exchange column, and developed to become fluorescent with reaction reagent. The chromatogram of each ESD phenotype was distinct from those of the other phenotypes. ESD protein was confirmed by isoelectric focusing in the HPLC fraction that was referred for ESD typing. This HPLC method can be used to determine the common ESD phenotypes in blood.  相似文献   
107.
We studied facial expressions during pathological laughing and crying in 6 patients using EMG investigation. Increased EMG discharges of M. frontalis and M. corrugator supercilii are characteristic of pathological laughing and crying in addition to an increase of EMG discharges of M. orbicularis oculi, M. levator labii superiors, M. zygomaticus major, M. risorius and M. mentalis which we observed during natural laughing. Its patterns of facial expressions are similar to that of crying in normals. From the fact that normals show the same expression of laughing and crying in an extreme emotional outburst, we speculate that pathological laughing and crying is maximal manifestations of facial expressions caused by a release phenomenon of the upper center.  相似文献   
108.
The relation between smoking and risk of asthma has been well-examined; however little attention has been paid to the correlation between smoking and asthma symptoms. The aims of this study were to examine respiratory symptoms in asthmatics with a highly prevalent use of inhaled corticosteroid (ICS) and to assess the effects of smoking and its cessation. A cross-sectional study of pulmonologist-based 3197 asthmatics (men 45.2%, ages 20-97) was performed using a questionnaire about smoking habits, the incidence and frequency of symptoms (sputum, cough and wheezing, night symptoms, and shortness of breath), physical activity interference, and medication. Although 81.4% of the patients used ICS according to the international guideline, 14.9% had activity interference, and daily symptoms remained in 43.3%. At the time of the questionnaire, 21.6% were current and 25.1% were ex-smokers. In multiple logistic regression analysis, the factors of significance (p < 0.0001) were (1) smoking; for all four symptoms, (2) age and duration of asthma; for shortness of breath. Current smokers were at a risk of sputum (age-adjusted odds ratio 2.32 [95% confidence interval 1.73-3.11]; 2.09 [1.57-2.79]), of cough and wheezing (2.38 [1.81-3.14]; 1.78 [1.35-2.36]), of night symptoms (1.95 [1.41-2.60]; 1.47 [1.09-1.98]), and of shortness of breath (1.70 [1.26-2.28]; 1.30 [0.97-1.75]) in men and women, respectively. These ratios in ex-smokers decreased to the level similar to nonsmokers. Although 81.4% of asthmatic patients used ICS, 43.3% complained of daily respiratory symptoms, especially sputum. It is suggested that the effects of ICS on asthma symptoms may be interfered with by smoking and therefore more emphasis should be placed on cessation of smoking.  相似文献   
109.
Seven consecutive clinical cases of necrotising fasciitis or necrotic skin lesions (42-78 years old; average 65.0 years of age, three females and four males) due to group A Streptococcus, group B Streptococcus, methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa in the lower extremities, who demonstrated rapid systemic symptoms, were investigated for the usefulness of a bilayer artificial dermis, derived from porcine tendons, over 4 +/- 2.4 years (1-7 years). All surgical debridement was confirmed as sufficiently deep and wide for clinically infected lesions and artificial dermis was applied to all wounds. The average interval to secondary split-thickness skin grafting was about 17.5 days (17.5 +/- 2.44 days, 21 days max., 14 days min.) and the average thickness was 0.009 +/- 0.0022 in. (range: 0.006 - 0.012 in.). No clinical problems were noted during the application of the artificial dermis and the subsequent skin grafting. Since, the donated skin graft was thin, the morbidity was minimised. The use of artificial dermis after extensive surgical debridement in necrotising fasciitis was easy and effective. Local or systemic infection was negligible.  相似文献   
110.
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