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   4148篇
  免费   252篇
  国内免费   28篇
耳鼻咽喉   53篇
儿科学   168篇
妇产科学   76篇
基础医学   611篇
口腔科学   95篇
临床医学   314篇
内科学   958篇
皮肤病学   179篇
神经病学   228篇
特种医学   152篇
外科学   365篇
综合类   35篇
预防医学   216篇
眼科学   93篇
药学   323篇
中国医学   18篇
肿瘤学   544篇
  2023年   50篇
  2022年   85篇
  2021年   125篇
  2020年   62篇
  2019年   97篇
  2018年   131篇
  2017年   112篇
  2016年   94篇
  2015年   103篇
  2014年   155篇
  2013年   166篇
  2012年   324篇
  2011年   312篇
  2010年   225篇
  2009年   149篇
  2008年   247篇
  2007年   265篇
  2006年   287篇
  2005年   234篇
  2004年   218篇
  2003年   208篇
  2002年   207篇
  2001年   53篇
  2000年   48篇
  1999年   47篇
  1998年   36篇
  1997年   32篇
  1996年   27篇
  1995年   31篇
  1994年   23篇
  1993年   18篇
  1992年   23篇
  1991年   24篇
  1990年   23篇
  1989年   25篇
  1988年   17篇
  1987年   17篇
  1986年   13篇
  1985年   19篇
  1984年   11篇
  1983年   10篇
  1982年   13篇
  1981年   4篇
  1980年   6篇
  1979年   4篇
  1978年   5篇
  1977年   8篇
  1976年   5篇
  1973年   4篇
  1968年   6篇
排序方式: 共有4428条查询结果,搜索用时 36 毫秒
81.
Long-term, low-dose erythromycin monotherapy, based on the anti-inflammatory effects of macrolides, has been reported to have the potential to suppress the exacerbation of Mycobacterium avium complex (MAC) lung disease with less toxicity. It remains unclear whether erythromycin monotherapy induces cross-resistance to clarithromycin, a key drug for MAC. To clarify this point, we conducted a retrospective, single-center, case-series study on patients with MAC lung disease who underwent erythromycin monotherapy for at least 6 months. Drug susceptibility tests, before and after erythromycin treatment initiation, were analyzed. Thirty-three patients were included in our study. All 33 patients showed susceptibility to clarithromycin for MAC both before and after erythromycin monotherapy. There was no significant difference in clarithromycin minimum inhibitory concentrations between before and after erythromycin treatment (median difference = 0 μg/ml; P = .313, Wilcoxon's signed-rank test). We conclude that erythromycin monotherapy for MAC lung disease may not induce cross-resistance to clarithromycin.  相似文献   
82.
Clinical Rheumatology - Eosinophilic fasciitis (EF) is a rare connective tissue disease that causes inflammation and fibrosis of the fascia, inducing pain and motor dysfunction. Characteristic skin...  相似文献   
83.
AIDS and Behavior - We aimed to measure social protection coverage among the general population, women and men living with HIV (WLHIV, MLHV), female and male sex workers (FSW, MSW), men who have...  相似文献   
84.
We previously characterized the patients with autosomal recessive hypercholesterolemia (ARH) as having severe hypercholesterolemia and retarded plasma low-density lipoprotein (LDL) clearance despite normal LDL receptor (LDLR) function in their cultured fibroblasts, and we identified a mutation in the ARH locus in these patients. ARH protein is an adaptor protein of the LDL and reportedly modulates its internalization. We developed ARH knockout mice (ARH-/-) to study the function of this protein. Plasma total cholesterol level was higher in ARH-/- mice than that in wild-type mice (ARH+/+), being attributed to a 6-fold increase of LDL, whereas plasma lipoprotein was normal in the heterozygotes (ARH+/-). Clearance of 125I-LDL from plasma was retarded in ARH-/- mice, as much as that found in LDLR-/- mice. Fluorescence activity of the intravenously injected 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI)-LDL was recovered in the cytosol of the hepatocytes of ARH+/+ mice, but not in those of ARH-/- or LDLR-/- mice. Also, less radioactivity was recovered in the liver of ARH-/- or LDLR-/- mice when [3H]cholesteryl oleyl ether (CE)-labeled LDL was injected. In contrast, uptakes of [3H]CE-labeled LDL, 125I-LDL, and DiI-LDL were all normal or slightly subnormal when the ARH-/- hepatocytes were cultured. We thus concluded that the function of the hepatic LDLR is impaired in the ARH-/- mice in vivo, despite its normal function in vitro. These findings were consistent with the observations with the ARH homozygous patients and suggested that certain cellular environmental factors modulate the requirement of ARH for the LDLR function.  相似文献   
85.
OBJECTIVES: The goal of the present study was to compare the accuracy of in vivo tissue characterization obtained by intravascular ultrasound (IVUS) radiofrequency (RF) data analysis, known as Virtual Histology (VH), to the in vitro histopathology of coronary atherosclerotic plaques obtained by directional coronary atherectomy. BACKGROUND: Vulnerable plaque leading to acute coronary syndrome (ACS) has been associated with specific plaque composition, and its characterization is an important clinical focus. METHODS: Virtual histology IVUS images were performed before and after a single debulking cut using directional coronary atherectomy. Debulking region of in vivo histology image was predicted by comparing pre- and post-debulking VH images. Analysis of VH images with the corresponding tissue cross section was performed. RESULTS: Fifteen stable angina pectoris (AP) and 15 ACS patients were enrolled. The results of IVUS RF data analysis correlated well with histopathologic examination (predictive accuracy from all patients data: 87.1% for fibrous, 87.1% for fibro-fatty, 88.3% for necrotic core, and 96.5% for dense calcium regions, respectively). In addition, the frequency of necrotic core was significantly higher in the ACS group than in the stable AP group (in vitro histopathology: 22.6% vs. 12.6%, p = 0.02; in vivo virtual histology: 24.5% vs. 10.4%, p = 0.002). CONCLUSIONS: Correlation of in vivo IVUS RF data analysis with histopathology shows a high accuracy. In vivo IVUS RF data analysis is a useful modality for the classification of different types of coronary components, and may play an important role in the detection of vulnerable plaque.  相似文献   
86.
A 79-year-old man was referred to this department due to the presence of extrahepatic bile duct carcinoma with a tumor at the left chest wall. The lesion was suspected to be a metastasis of bile duct carcinoma to the left wall, however, computed tomography (CT) revealed no regional lymph node or liver metastases. In addition, cytological and pathological examinations did not show malignancy. At the time of admission, the white blood cell count was 21 460 cells/μL (neutrophils, 18 240 cells/μL) and this elevated to 106 040 before death. In addition, serum granulocyte colony-stimulating factor (G-CSF) was elevated. At 28 d after admission, the patient died. An autopsy showed a poorly differentiated adenocarcinoma with sarcomatous change, which had slightly invaded into the pancreas around the bile duct, and was found in the distal bile duct with multiple metastases to the chest wall, lung, kidney, adrenal body, liver, mesentery, vertebra and mediastinal and para-aortic lymph nodes, without locoregional lymph node and liver metastasis. The cancer cells showed positive immunohistochemical staining for anti-G-CSF antibody. This is believed to be the first report of an extrahepatic bile duct carcinoma that produces G-CSF. Since G-CSF-producing carcinoma and sarcomatous change of the biliary tract leads to poor prognosis, early diagnosis and treatment are needed. When infection is ruled out, the G-CSF in serum should be examined. In addition, examinations such as bonescintigraphy and chest CT should also be considered for distant metastasis.  相似文献   
87.
Interferon (IFN) has been shown to be effective for chronic hepatitis C. This study investigated changes of alanine aminotransferase (ALT) and HCV-RNA in chronic hepatitis C patients treated withα-IFN. IFN was given to 73 patients with HCV-RNA positive chronic hepatitis C. The pattern of changes in ALT activity after IFN aministration was classified into five types. Type 1 was characterized by normalization of ALT (≤25 K.U) during IFN administration and sustained normalization after the IFN therapy. Type 2 involved a rebound of ALT after termination of IFN therapy and subsequent normalization. Type 3 had no ALT normalization during IFN administration, with normalization after the completion of the therapy. Type 4 involved transient normalization of ALT level during IFN therapy, with a subsequent reversion to abnormal levels after the termination of IFN therapy. Type 5 showed sustained abnormally high levels of ALT activity both during and after treatment. Twenty four patients (32.9%) had sustained normalization ALT (≤25 K.U) after the termination of IFN treatment. The HCV-RNA negative rate at 6 months after IFN therapy in patients with sustained normalization of ALT was 87.5% (21/24).  相似文献   
88.
The aim of the study described here was to clarify the diagnostic value of the fluttering sign, a new sign that characterizes hepatic hemangiomas in gray-scale ultrasonography (US). It refers to a phenomenon in which the speckled echogenicity inside the hemangioma changes continuously and seems to be moving. A total of 172 hemangiomas diagnosed with contrast-enhanced US were evaluated. The fluttering sign was found in 123 of 172 hemangiomas (71.5%). Its prevalence was significantly higher than that of the marginal strong echo (89/172, 51.7%, p < 0.001), posterior acoustic enhancement (103/172, 59.9%, p = 0.031) and chameleon sign (100/172, 58.1%, p = 0.013). In addition, the fluttering sign was observed significantly more frequently in mixed or hypo-echoic tumors than in hyper-echoic tumors (p < 0.001), relatively large tumors (p < 0.001) and tumors that were less than 5 cm from the body surface (p = 0.015). The fluttering sign in gray-scale US has great potential to be a new complementary sign for the diagnosis of hemangioma.  相似文献   
89.
90.
It is often difficult to predict the response to telaprevir-pegylated interferon (PEG-IFN)-ribavirin triple therapy and the appearance of telaprevir-resistant variants. The present study determined the predictive factors of a sustained virological response (SVR) to 12- or 24-week triple therapy (T12PR12 or T12PR24, respectively) in 194 Japanese patients infected with hepatitis C virus genotype 1b (HCV-1b). The study also evaluated whether ultradeep sequencing technology can predict at baseline the emergence of resistant variants after the start of therapy. Analysis of the data of the entire group indicated that an SVR was achieved in 78% of the patients. Multivariate analysis identified IL28B rs8099917 (genotype TT), the substitution of amino acid (aa) 70 (Arg70), response to prior treatment (naive or relapse), PEG-IFN dose (≥1.3 μg/kg of body weight), and treatment regimen (T12PR24) as significant determinants of SVR. Among patients of the T12PR24 group, 92% with genotype TT achieved an SVR, irrespective of a substitution at aa 70. In patients with the non-TT genotype, an SVR was achieved in 76% of those with Arg70, while only 14% of patients with the non-TT genotype, Gln70(His70), and nonresponse to ribavirin combination therapy achieved an SVR. Ultradeep sequencing was conducted for 17 patients who did not achieve an SVR to determine the emergence of resistant variants during therapy. De novo resistant variants were detected in 16 of 17 patients (94%), regardless of the variant frequencies detected at baseline. In conclusion, the results indicate that the response to triple therapy can be predicted by the combination of host, viral, and treatment factors and that it is difficult to predict at baseline the telaprevir-resistant variants that emerge during triple therapy, even with the use of ultradeep sequencing.  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