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   19127篇
  免费   950篇
  国内免费   115篇
耳鼻咽喉   141篇
儿科学   302篇
妇产科学   195篇
基础医学   2309篇
口腔科学   452篇
临床医学   1236篇
内科学   4514篇
皮肤病学   366篇
神经病学   1429篇
特种医学   1172篇
外科学   3576篇
综合类   65篇
一般理论   1篇
预防医学   569篇
眼科学   253篇
药学   1224篇
中国医学   58篇
肿瘤学   2330篇
  2023年   102篇
  2022年   194篇
  2021年   450篇
  2020年   225篇
  2019年   327篇
  2018年   373篇
  2017年   367篇
  2016年   412篇
  2015年   435篇
  2014年   579篇
  2013年   650篇
  2012年   1039篇
  2011年   1178篇
  2010年   674篇
  2009年   559篇
  2008年   956篇
  2007年   1070篇
  2006年   1064篇
  2005年   1153篇
  2004年   1049篇
  2003年   1023篇
  2002年   1075篇
  2001年   424篇
  2000年   393篇
  1999年   432篇
  1998年   319篇
  1997年   227篇
  1996年   258篇
  1995年   186篇
  1994年   185篇
  1993年   154篇
  1992年   290篇
  1991年   228篇
  1990年   212篇
  1989年   192篇
  1988年   209篇
  1987年   177篇
  1986年   141篇
  1985年   155篇
  1984年   113篇
  1983年   101篇
  1982年   63篇
  1979年   79篇
  1978年   64篇
  1977年   50篇
  1975年   46篇
  1974年   54篇
  1973年   51篇
  1972年   56篇
  1969年   50篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
miRNA‐221 (miR‐221) is known to be abnormally expressed in many human cancers. The serum levels of miR‐221 have been reported as a tumor marker for malignant melanoma (MM). We hypothesized that the hair shaft miR‐221 levels may be increased in patients with MM. We therefore assessed the possibility that hair shaft miR‐221 levels could be a marker for MM. The hair shaft miR‐221 levels were significantly higher in patients with MM than controls. The rates of increased hair shaft miR‐221 levels above the cut‐off value were comparable to those of serum 5‐S‐CD, which is a tumor marker commonly used for MM. Measurements of the hair shaft miR‐221 levels could have potential clinical value in the detection of MM. This is the first report investigating the hair shaft levels of an miRNA in patients with MM. Our investigations offer new insight into the relationship between miR‐221 and MM, and may provide a new, non‐invasive way to screen for melanoma.  相似文献   
4.
Even for patients with multiple pancreaticoduodenal aneurysms, successful treatment with noninvasive operative procedures can be employed, if intraoperative devices are considered. A 73‐year‐old man, without any symptoms, was admitted to our hospital and had computed tomography (CT) scanning to examine his liver for hepatitis C virus (HCV). Selective superior mesenteric artery (SMA) angiography confirmed multiple aneurysms in the anterior inferior pancreaticoduodenal artery (AIPDA), one aneurysm in the posterior inferior mesenteric artery (PIPDA), and another in the occluded celiac trunk, all with severe calcification. All of the aneurysms were thought to communicate with each other. With the celiac artery occlusion, the right hepatic artery (RHA) was revealed to be supplied by collateral arteries from the aneurysms in the AIPDA, and the left hepatic artery was shown to be supplied by collaterals from the left gastric artery. Intraoperative Doppler echography, at the time of the clamping of both IPDAs, demonstrated a marked decrease of blood velocity in all aneurysms (before clamping, >50 cm/s; after, <10 cm/s), although loss of pulsation and a marked decrease of flow in the RHA were inevitable. Therefore, each of these two IPDAs were ligated on the proximal side to the aneurysm, thus preserving the blood flow of the pancreas head fed by the PIPDA; bypass grafting from the AIPDA to the RHA, using the great saphenous vein, was done at the same time. After the creation of an anastomosis, the hepatic venous oxygen saturation (ShvO2) increased from 38% (at the time of ligation of the IPDAs) to 57% under ventilation. The patient's postoperative clinical course was uneventful. We describe and discuss our successful noninvasive operative management of multiple pancreaticoduodenal aneurysms, done while monitoring the blood flow and ShvO2, with some consideration of the literature.  相似文献   
5.
6.
To form the human body and maintain the integrity of its complex tissues, individual cells need to hold tightly to each other. The desmosome is the major type of intercellular adhesive junction, and has desmoglein (Dsg), a cadherin type cell-cell adhesion molecule, as a transmembrane component. Dsg is now known to be targeted in autoimmune diseases, infectious diseases, as well as inherited diseases. Patients with pemphigus, an autoimmune blistering disease of the skin and mucous membrane, have IgG autoantibodies directed against Dsg1 and Dsg3. A subset of patients with pemphigus have Dsg1/Dsg4 crossreacting IgG autoantibodies. Exfoliative toxins produced by Staphylococcal aureus, which causes Staphylococcal Scalded Skin Syndrome (SSSS) and bullous impetigo, specifically digest Dsg1. A subset of patients with SSSS develop a low titer of anti-Dsg1 IgG autoantibodies. A mutation in DSG1 gene causes striate palmoplantar keratoderma and a mutation in DSG4 gene causes inherited hypotrichosis. It is not clear why so many diseases are clustered in desmogleins, but there must be a reason for this. Studies on desmogleins will provide an important framework to understand the mysteries between autoimmunity and infection.  相似文献   
7.
Summary Fourteen patients with HTLV-1-associated myelopathy were treated with high-dose intravenous gammaglobulin (IVGG). Ten received 10 g/day of IVGG and 4 received 400 mg/kg of body-weight/day of IVGG for 5 consecutive days. Improvement of spastic paraparesis was observed in 10 within 7 days of the commencement of IVGG. The therapeutic effects were sustained for more than 3 weeks in some patients. There were no side effects. Analysis of factors of relevance to the clinical improvement with IVGG showed that the beneficial response was preferentially found in patients having a high CSF titre of anti-HTLV-I antibodies, a high CSF IgG level and a marked brain MRI abnormality.  相似文献   
8.
Prolidase was highly purified from human liver and erythrocytes. NaDodSO4/acrylamide gel electrophoresis revealed that these preparations contained a major protein with MW = 56,000. The mass of prolidase was estimated on gel filtration to be MW = 97,000, for both enzyme preparations. A monoclonal antibody was raised against the liver enzyme and a specific antiserum against the erythrocyte enzyme. The monoclonal antibody (EP-2) recognized prolidase from erythrocytes and liver, in equal proportions. The antiserum also recognized the enzyme from erythrocytes and liver. Immunoprecipitation studies with these antibodies suggested only a single species of prolidase in erythrocytes and liver. Using an immobilized monoclonal antibody (EP-2) as an immunoadsorbent, prolidase was partially purified from crude extracts, and the protein of the partially purified enzyme was identified by immunoblotting using antiserum. A protein band with a MW = 56,000 was demonstrated specifically when crude extracts from the liver and erythrocytes were examined using NaDodSO4/acrylamide gel electrophoresis. The subunit protein was absent in erythrocytes from a patient with prolidase deficiency. We propose that the absence of the subunit is one cause of the prolidase deficiency.  相似文献   
9.
The correlation between the treadmill exercise test results and the hemodynamic data of 152 patients with previous myocardial infarction were investigated. The patients were classified into 4 groups as follows: H1 left ventricular end-diastolic pressure (LVEDP) less than or equal to 12 mmHg and cardiac index (CI) greater than or equal to 3.0 L/min/m2; H2 LVEDP greater than 12 mmHg and CI greater than or equal to 3.0 L/min/m2; H3 LVEDP less than or equal to 12 mmHg and CI less than 3.0 L/min/m2; and H4 LVEDP greater than 12 mmHg and CI less than 3.0 L/min/m2. The duration of the exercise was significantly shortened for group H4 than group H1 (p less than 0.01). The maximal ST segment elevation (mSTe) was significantly increased for group H3 and group H4, versus group H1 (p less than 0.05). The number of ST segment elevations and mSTe/maximal heart rate were significantly increased for group H3 (p less than 0.05) and group H4 (p less than 0.01) versus group H1. The incidence of exercise-induced premature ventricular contractions (PVCs) was significantly increased in group H3 and group H4, versus group H1 (p less than 0.05). There were no significant differences in the maximal heart rate, double product, and ST segment depression among the 4 groups. Our data indicate that the groups with impaired left ventricular functions tend to decrease the duration of the exercise and to increase ST segment elevation and PVC frequencies during exercise.  相似文献   
10.
St. Jude Medical valve replacement was performed in 1,039 patients; 320 had aortic (AVR), 543 mitral (MVR), and 176 had double valve replacement (DVR). There were 44(4.2%) early deaths. Follow-up extended in 995 patients from 10 to 130 months, with a cumulative period of 2,730 patients-years. The overall survival rates of AVR, MVR, and DVR patients at 10 years were 60.5%, 89.6%, 90.3% respectively. The linearized incidences of valve thrombosis, thromboembolism, anticoagulation-related hemorrhage, prosthetic valve endocarditis, and significant hemolysis were as follows: 0.11%/pt-yr, 1.33%/pt-yr, 0.04%/pt-yr, 0.18%/pt-yr, and 0.11%/pt-yr, respectively. There were no structural failure after 10 years follow-up. Reoperation (explant and re-replacement or suture repair) was required in 10 patients. Seven of them had periprosthetic leakage, 2 had valve thrombosis, and one underwent reoperation because of a technical error. Actuarially over 98% of patients were free of valve-related mortality at 10 years. St. Jude Medical valve is an excellent alternative for use in the surgical treatment of valvular heart disease.  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