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   5724篇
  免费   247篇
  国内免费   30篇
耳鼻咽喉   34篇
儿科学   114篇
妇产科学   51篇
基础医学   607篇
口腔科学   78篇
临床医学   359篇
内科学   1445篇
皮肤病学   107篇
神经病学   489篇
特种医学   146篇
外科学   1096篇
综合类   24篇
预防医学   159篇
眼科学   115篇
药学   396篇
中国医学   11篇
肿瘤学   770篇
  2023年   31篇
  2022年   59篇
  2021年   93篇
  2020年   69篇
  2019年   68篇
  2018年   95篇
  2017年   88篇
  2016年   105篇
  2015年   124篇
  2014年   150篇
  2013年   214篇
  2012年   295篇
  2011年   400篇
  2010年   198篇
  2009年   177篇
  2008年   318篇
  2007年   424篇
  2006年   417篇
  2005年   395篇
  2004年   396篇
  2003年   419篇
  2002年   451篇
  2001年   47篇
  2000年   58篇
  1999年   69篇
  1998年   133篇
  1997年   82篇
  1996年   87篇
  1995年   61篇
  1994年   54篇
  1993年   48篇
  1992年   36篇
  1991年   40篇
  1990年   38篇
  1989年   30篇
  1988年   24篇
  1987年   29篇
  1986年   18篇
  1985年   20篇
  1984年   21篇
  1983年   13篇
  1982年   10篇
  1981年   14篇
  1980年   19篇
  1979年   10篇
  1978年   7篇
  1977年   12篇
  1976年   5篇
  1974年   6篇
  1973年   5篇
排序方式: 共有6001条查询结果,搜索用时 31 毫秒
81.
82.
Abstract

Despite similar benign histological appearances, proliferative activity of meningiomas varies tumor to tumor, and even region to region in a tumor. To predict proliferative potential before surgery, we compared regional uptake of2-[18F]fluoro-2-deoxyglucose ([18F]FDC) and L-fmethyl-11 CJmethionine ([71C]MET) with histological indices of tumor proliferative activity in 17 specimens from six patients with meningioma obtained by PET guided stereotactic biopsies. Uptake of I11C]MET', an index of protein synthesis rate, significantly correlated not only with the count of nucleolar organizer regions (NORs), a histological index of protein synthesis, but also with Ki-67 index, a histological index of proliferative activity. On the other hand, [18F]FDC uptake showed no significant correlation with Ki-67 index or clinical malignancy. These results suggest that [11 C]MET-PET is a useful tool for predicting tumor proliferative potential in meningiomas. [Neurol Res 1999; 21: 640-644]  相似文献   
83.
The systemic hemodynamic and coronary dilative responses to sublingual nitroglycerin were studied in patients receiving transdermal nitroglycerin. A total of 48 patients with coronary artery disease were divided into 4 groups: 12 patients receiving 1 tablet of sublingual nitroglycerin without transdermal nitroglycerin (Group 1), 12 patients receiving 1 tablet of sublingual nitroglycerin with 12-hour-daily intermittent therapy of transdermal nitroglycerin (Group 2), 12 patients receiving 1 tablet of sublingual nitroglycerin with continuous therapy of transdermal nitroglycerin (Group 3), and 12 patients receiving 2 tablets of sublingual nitroglycerin with continuous therapy of transdermal nitroglycerin (Group 4). Before and during administration of sublingual nitroglycerin, aortic pressure, left ventricular pressure, and coronary artery diameter were examined at diagnostic cardiac catheterization in all patients. During sublingual nitroglycerin, the decreases of aortic systolic pressure and left ventricular end-diastolic pressure were greater in Group 1, 2, and 4 than in Group 3. Dilation of coronary arteries by sublingual nitroglyerin tended to be greater in Group 1, 2, and 4 than in Group 3. Thus, the effects of sublingual nitroglycerin for the relief of ischemia might be more prominent in patients with intermittent therapy of transdermal nitroglycerin than in those with continuous therapy. The increased dose of sublingual nitroglycerin for the relief of ischemia might be more effective in patients with continuous therapy of transdermal nitroglycerin.  相似文献   
84.
85.
A party of 57 people dined together in a restaurant in Hamamatsu City on December 11, 2001. The next day, 22 of them developed symptoms of acute gastroenteritis, such as diarrhea, vomiting, and fever. Examination of 4 fecal specimens from these patients by ELISA for Norovirus (Norwalk-like virus, NV) detected both genogroup I (GI) and genogroup II (GII) NV in all the 4 specimens. In addition, RT-PCR and real-time PCR methods for NV detected the NV gene. Approximately one month after the outbreak of the food poisoning (acute gastroenteritis) by NV, 4 individuals in the same party developed type A hepatitis. Both RT-PCR and real-time PCR methods for hepatitis A virus (HAV) detected the HAV gene in their fecal specimens. The party of these patients ate purple Washington clam (Saxidomus purpuratus, imported from China) steamed with red pepper. Since this food appeared to have caused the viral infections, the one with the same lot number was subjected to viral examinations, which successfully detected the NV GI, NV GII, and HAV genes. These results led to the conclusion that the clam contaminated with NV and HAV had caused the food poisoning. The DNA sequences of the NV detected in the patients and the clam had 74 to 99% homology, indicating strains of various genotypes. All the strains of HAV that were derived from the patients and the clam were genotype 1A, and these sequences had over 95% homology, but were not completely identical. This outbreak led to the demonstration of imported fishery products as a cause of type A hepatitis, and indicated the need for guiding and enlightening people on the importance of adequate cooking of bivalves.  相似文献   
86.
Background:   The relationship between lipoprotein(a) (Lp(a)) and ischemic stroke is still controversial in the elderly. The purpose of the present paper was to evaluate the significance of Lp(a) in the development of extracranial carotid lesions and ischemic stroke.
Methods:   A total of 371 elderly subjects, studied with carotid ultrasonography (US) and brain computed tomography (CT), was stratified into two groups according to serum Lp(a) levels: the normal Lp(a) and high Lp(a) (>40 mg/dL) groups. Carotid plaques were divided into three types based on the US echogenicity: hypoechoic, hyperechoic, and heterogeneous plaques. Low-density areas (LDA) on brain CT images were classified into three groups depending on their distribution: basal ganglionic, cortical and only leuko-araiosis types.
Results:   The incidence of bilateral carotid lesions and the ratios of hypoechoic and heterogeneous plaques were significantly higher in the high Lp(a) group than in the normal Lp(a) group. Both the mean height and length of plaque were also greater in the high Lp(a) group. Mean Lp(a) levels were significantly elevated in cases with hypoechoic and heterogeneous types, compared to the cases without lesions. Higher mean Lp(a) levels were seen in cases with any kind of LDA than in normal subjects on CT, but there was no significant difference in the incidence of each LDA between the two groups.
Conclusions   These findings indicate that serum Lp(a) is strongly related to carotid lesions, especially hypoechoic and heterogeneous plaque types, in Japanese elderly patients. This suggests that Lp(a) could promote the formation of lipid-rich atheromatous plaque with intraplaque hemorrhage or superimposed thrombi. Serum Lp(a) also seemed to be a risk for all types of LDA.  相似文献   
87.
The principal management of acute cholecystitis is early cholecystectomy. However, percutaneous transhepatic gallbladder drainage (PTGBD) may be preferable for patients with moderate (grade II) or severe (grade III) acute cholecystitis. For patients with moderate (grade II) disease, PTGBD should be applied only when they do not respond to conservative treatment. For patients with severe (grade III) disease, PTGBD is recommended with intensive care. Percutaneous transhepatic gallbladder aspiration (PTGBA) is a simple alternative drainage method with fewer complications; however, its clinical usefulness has been shown only by case-series studies. To clarify the clinical value of these drainage methods, proper randomized trials should be done. This article describes techniques of drainage for acute cholecystitis.  相似文献   
88.
Familial hypertrophic cardiomyopathy (HC) can be caused by mutations in 9 different genes encoding sarcomere proteins expressed in cardiac muscle. To date, only 13 different mutations in the cardiac troponin T (cTnT) gene have been reported to cause HC. Clinical characteristics and prognosis associated with mutations of this gene have not been well characterized owing to the small size and composition of affected families. The aim of this study was to determine the characteristic phenotype of patients with HC caused by a novel cTnT gene mutation, Lys273Glu. Two hundred Japanese probands with HC were screened for mutations in the cTnT gene. The Lys273Glu missense mutation was present in 9 persons from 2 unrelated pedigrees. They exhibited different cardiac morphologies: 1 had a dilated cardiomyopathy-like feature, 7 had left ventricular hypertrophy with normal left ventricular systolic function, and the 6 of them had asymmetric septal hypertrophy. A 1-year-old boy was not evaluated with echocardiography. The mean maximum wall thickness was 18.0 +/- 5.5 mm (range 8 to 24). There were 7 histories of sudden death in 1 of the 2 families. The Lys273Glu substitution in the cTnT gene shows a high degree of penetrance (100% in persons aged >20 years), a high incidence of sudden death, and a partial transition from hypertrophic to dilated cardiomyopathy. Because the location of a mutation appears to influence the development of a phenotype, we suggest that the precise definition of the disease-causing mutation can provide important prognostic information about affected members.  相似文献   
89.
We experienced 108 cases of Fusobacterium associated infections, including otolaryngeal, oral, pleuropulmonary, intraabdominal, skin and soft tissue infections, at Aomori Prefectural Hospital during The 5 year-period from 1995 to 1999. A total of 433 organisms, included 113 Fusobacterium spp. (80 Fusobacterium nucleatum, 18 Fusobaterium necrophorum, 5 Fusobacterium varium, 4 Fusobacterium mortiferum, 6 Fusobacterium spp.), were recovered with an average of 4.0 organisms per case of the 108 cases, 68% were mixed aerobic and anaerobic and yielded 185 anaerobic bacteria (2.5 per case) and 137 aerobic bacteria (1.9 per case) with an average of 4.4 per case. The remaining 32% were purely anaerobic and yielded 111 organisms with an average of 3.2 per case, Prevotella spp., Bacteroides fragilis group, Streptococcus milleri group, Enterobacteriaceae, Peptostreptococcus spp. Staphylococcus spp. were most frequently coisolated with Fusobacterium spp.  相似文献   
90.
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