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   15902篇
  免费   653篇
  国内免费   136篇
耳鼻咽喉   109篇
儿科学   355篇
妇产科学   136篇
基础医学   1886篇
口腔科学   296篇
临床医学   972篇
内科学   4235篇
皮肤病学   265篇
神经病学   1374篇
特种医学   612篇
外科学   2814篇
综合类   67篇
一般理论   1篇
预防医学   372篇
眼科学   212篇
药学   1044篇
中国医学   24篇
肿瘤学   1917篇
  2023年   91篇
  2022年   193篇
  2021年   328篇
  2020年   157篇
  2019年   257篇
  2018年   264篇
  2017年   196篇
  2016年   296篇
  2015年   322篇
  2014年   399篇
  2013年   550篇
  2012年   899篇
  2011年   990篇
  2010年   571篇
  2009年   483篇
  2008年   979篇
  2007年   990篇
  2006年   1024篇
  2005年   1035篇
  2004年   1000篇
  2003年   1005篇
  2002年   1032篇
  2001年   256篇
  2000年   231篇
  1999年   286篇
  1998年   286篇
  1997年   206篇
  1996年   188篇
  1995年   173篇
  1994年   161篇
  1993年   154篇
  1992年   157篇
  1991年   174篇
  1990年   150篇
  1989年   142篇
  1988年   108篇
  1987年   99篇
  1986年   101篇
  1985年   93篇
  1984年   78篇
  1983年   65篇
  1982年   50篇
  1981年   42篇
  1980年   41篇
  1979年   63篇
  1977年   43篇
  1975年   31篇
  1974年   34篇
  1973年   26篇
  1972年   26篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
A 74-year-old man with combined valvular disease with a recent cerebral infarction was admitted. While undergoing thorough examination for valvular disease, absent right superior vena cava (RSVC) and persistent left superior vena cava (PLSVC) were recognized. Chest X-ray film suggested a right arch protrusion, and CT and venogram confirmed the diagnosis. During surgery, replacement of the mitral and aortic valves and annuloplasty of the tricuspid valve were performed. A blood draining cannula was inserted in retrograde fashion from the coronary sinus into the PLSVC, without any difficulties in the tricuspid valve repair. Due to bradycardic atrial fibrillation, we believed that it would be difficult to insert an endocardial electrode postoperatively, hence myocardial electrode was placed in the right ventricular wall. Absent RSVC combined with PLSVC is very rare, and a patient who underwent combined valve surgery with this rare anatomical abnormality is herein presented.  相似文献   
32.
33.
The CA-50 enzyme immunoassay kit (EIA kit) that has been developed with the use of C-50 monoclonal antibody prepared by L. Lindholm et al. was evaluated for diagnosis of human cancer. The levels of CA-50 in the sera were determined using this kit supplied from Mitsui Pharmaceuticals, Inc. Co. in 759 healthy donors, 728 patients with benign disease and 1,263 untreated patients with cancer. A CA-50 concentration of 40 U/ml of serum was used as the cut-off value. Patients with pancreatic cancer and patients with bile duct cancer had high positive incidence of 75% and 68%, respectively, compared with a low positive incidence of under 40% in patients with other cancers. On the other hand, positive rates in patients with benign disease were as low as 13%. Comparison of the serum levels of CA-50 with CA19-9 in the same samples did not exhibit complete positive correlation in patients with pancreatic cancer, patients with bile duct cancer and patients with liver cancer. These findings indicated that C-50 antibody reacted with two epitopes of CA19-9 and sialosyllactotetraose. From the above results, the usefulness of CA-50 as a tumor marker for pancreatic cancer and bile duct cancer was recognized with this EIA kit.  相似文献   
34.
A 36-year-old man was admitted to a hospital with complaints of fever, polyarthralgia and dyspnea. Erythema was observed on his face, extensor surface of the fingers and extremities, and a chest X-ray revealed massive bilateral pleural effusion. He had no sign of myopathy at this point. Pleural fluid was proved to be exudative and contained extremely high levels of hyaluronic acid. He was also complicated with interstitial pneumonitis and was given a pulse therapy with methyl prednisolone followed by daily administration of 55 mg prednisolone (PSL). Twenty days after the commencement of the therapy, pleural effusion decreased but muscle weakness gradually appeared, accompanied by elevation of myogenic enzymes. Myogenic changes on electromyogram, and irregularity of the muscle fibers with slight inflammatory cell infiltrates in a biopsy specimen were demonstrated. He was transferred to our hospital, and a diagnosis of dermatomyositis was made. Later, pleural effusion waxed and waned depending on the dosage of PSL, but no other causative disorder was demonstrated by extensive examinations. This case indicates that the pleuritis could be one of the vasculitic manifestations of dermatomyositis.  相似文献   
35.
36.
Farmer's lung disease is one type of hypersensitivity pneumonitis (HP) in dairy farmers, and is usually caused by Micropolyspora faeni (Mf). It has been reported that the positive rate of precipitin antibody to Mf in smoking dairy farmers is one-eighth to one-half of that in nonsmoking dairy farmers. To clarify the mechanism of this phenomenon, by using an experimental HP model in rabbits, we investigated 1) the effects of short (5 weeks) and long (20 weeks)-term cigarette smoke exposure on the antibody formation, 2) the effects of 30 weeks of smoke exposure on the accessory cell function of alveolar macrophages (AM). Smoking exerted variable influences on antibody production, depending on the duration of smoke exposure, and we confirmed that long-term smoke exposure had suppressive effects. In addition AM from smoked rabbits suppressed lymphoproliferative response to autologous spleen cells. It was concluded that in this experimental HP, smoking affects the functions of both AM and lymphocytes, and that it suppresses antibody production as long as the smoke exposure continues.  相似文献   
37.
Summary A case of a solid parotid tumour in a 16-year-old boy is presented. Histologically, the tumour demonstrated some peculiar findings. An acinar pattern was predominant although every component seen in the normal salivary gland was present, namely, serous and mucous gland acini, ducts, myoepithelial cells, adipose and lymphoid tissue. Large eosinophilic granules were abundant in the large acinar cell cytoplasm. Immunohistochemically, the tumour demonstrated the proteins which are present in the normal parotid gland, for example, amylase, lactoferrin and lysozyme. Electron microscopic features were quite similar to those of normal parotid tissue except for accumulation of a large number of cytoplasmic granules in the acinar cells. There has been no previous report of a tumour with the same features as seen in this case. Our pathological diagnosis is hamartoma, although the possibility of hyperplasia or neoplasia can not be excluded.  相似文献   
38.
Chemiluminescence (CL) analysis of monocytes and polymorphonuclear cells (PMNs) was performed on 13 patients with Crohn's disease (CD) and 10 healthy volunteers. The percentages of monocyte populations in mononuclear cells obtained from the patients with CD were greater than those from the healthy volunteers, but the numbers of PMNs were not different between the two groups. The peak level of phorbol myristate acetate (PMA)-induced CL activity generated by diluted whole blood from the patients with CD was more significantly elevated than that from the healthy volunteers, whereas the peak levels of opsonized zymosan-induced CL activity did not differ between the two groups. In monocytes, the peak levels of both PMA- and opsonized zymosan-induced CL activity were significantly higher in the patients with CD than in the healthy volunteers. CL in PMNs, however, showed no significant difference between CD and controls. It is suggested that monocytes of CD have a large capacity to generate active oxygen species. The present study suggests that excessive active oxygen species released by monocytes and perhaps macrophages may play an important role in formation of the intestinal lesions in CD.This work was supported by the Grant of Tokuteishitsukan from the Japanese Ministry of Welfare and Health.  相似文献   
39.
Background: Pancreatic carcinoma is one of the most lethal cancers. Because pancreatic carcinoma is still very difficult to diagnose in its early stage, many of these patients will be considered unsuitable for surgery. If a cytological diagnosis is obtained at initial endoscopic retrograde cholangiopancreatography (ERCP), suitable treatment will be initiated without delay. Methods: To increase the number of exfoliated cells from the pancreatic duct, we devised a new technique, pancreatic duct lavage fluid (PDLF), following bronchoalveolar lavage fluid. The present paper reports the effectiveness of cytological examination using PDLF in the diagnosis of pancreatic carcinoma. We examined 18 pancreatic carcinoma cases. After the endoscopic retrograde pancreatography (ERP), PDLF was collected from a double‐lumen catheter inserted into the main pancreatic duct. Saline injected from the lumen for the injection, and PDLF was aspirated from the other lumen for the guidewire at the same time. The cytological examination was performed using PDLF. Results: Exfoliated cells were more frequently found in PDLF from all patients. In 15 cases (83%), cytological examination of PDLF revealed positive cytological results as the diagnosis of pancreatic carcinoma. Conclusion: Cytological examination using PDLF has a high sensitivity for detection of pancreatic carcinoma. The new examination, PDLF, is simple, safe and effective, so we expect PDLF to become widely popular.  相似文献   
40.
Mechanical and biological properties of apatite composite resins   总被引:1,自引:0,他引:1  
M Okazaki  H Ohmae 《Biomaterials》1988,9(4):345-348
Well-crystallized hydroxyapatite was synthesized at 80 degrees C and pH 7.4, and mixed as filler with 2.2'(4-methacryloxydiethoxyphenyl) propane. BPO and DHPT were used as polymerization initiators. The compressive strength and Knoop hardness of the apatite composite resins increased with the increase of apatite content, and approached a plateau above an apatite-resin ratio (Ap/R) of 1. The thermal expansion coefficient of the composite with apatite-resin ratio Ap/R = 1 was almost equal to that of teeth. In tooth cavities, the composites seemed to adhere well to enamel without a bonding agent. The biocompatibility of the composites implanted hypodermically into rats appeared to improve with the increase of apatite content, and implants showed no significant inflammation after 1 wk and 4 wk.  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