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   3080篇
  免费   117篇
  国内免费   32篇
耳鼻咽喉   14篇
儿科学   43篇
妇产科学   33篇
基础医学   445篇
口腔科学   41篇
临床医学   187篇
内科学   1022篇
皮肤病学   22篇
神经病学   243篇
特种医学   85篇
外科学   331篇
综合类   22篇
预防医学   144篇
眼科学   12篇
药学   173篇
中国医学   7篇
肿瘤学   405篇
  2023年   10篇
  2022年   41篇
  2021年   69篇
  2020年   23篇
  2019年   41篇
  2018年   40篇
  2017年   35篇
  2016年   56篇
  2015年   49篇
  2014年   81篇
  2013年   86篇
  2012年   144篇
  2011年   144篇
  2010年   96篇
  2009年   105篇
  2008年   210篇
  2007年   252篇
  2006年   216篇
  2005年   228篇
  2004年   238篇
  2003年   211篇
  2002年   217篇
  2001年   42篇
  2000年   21篇
  1999年   34篇
  1998年   48篇
  1997年   49篇
  1996年   42篇
  1995年   48篇
  1994年   42篇
  1993年   40篇
  1992年   19篇
  1991年   30篇
  1990年   26篇
  1989年   20篇
  1988年   29篇
  1987年   21篇
  1986年   11篇
  1985年   14篇
  1984年   10篇
  1983年   12篇
  1982年   15篇
  1981年   16篇
  1980年   8篇
  1979年   4篇
  1978年   5篇
  1977年   3篇
  1976年   3篇
  1974年   5篇
  1973年   6篇
排序方式: 共有3229条查询结果,搜索用时 12 毫秒
11.
The disturbance of immune regulatory T cells is related to the pathogenesis of ulcerative colitis. Here we demonstrated and characterized the serum factor from ulcerative colitis patients that induced proliferation of intrathymic T cells. The factor isolated from the patient sera by a combination of gel filtration and anion-exchange chromatography induced proliferation of CD4+CD8 intrathymic T cells in the organ-cultured embryonic mouse thymus. Purification and amino acid sequence analysis of the serum factor demonstrated that the N-terminal 12 sequence was homologous to that of interleukin-7. SDS-PAGE and Western blot confirmed that purified serum factor was interleukin-7. Enzyme immunoassay demonstrated that the serum interleukin-7 concentration was significantly increased in the patients. PCR and Southern blot hybridization demonstrated that interleukin-7 mRNA expression was increased in the thymus tissues from patients but decreased in the colonic mucosa. Since interleukin-7 is a crucial cytokine for proliferation and differentiation of T cells in the thymus, the present study indicates that interleukin-7 may contribute to the disturbance of immune regulatory T cells in ulcerative colitis.  相似文献   
12.
VRK1 is a novel human putative serine/threonine kinase, and is located on chromosome 14 at band q32 where an autosomal recessive congenital microphthalmia (CMIC) is mapped. We isolated a polymorphic dinucleotide CA repeat marker from a genomic clone containing the human VRK1 gene. This polymorphism will be useful in genetic studies of disorders localized at the 14q32 region, such as CMIC. Received: October 8, 1998 / Accepted: October 16, 1998  相似文献   
13.
Sixty-two placentas with a triploid DNA content, which were analyzed by flow cytometry using paraffin-embedded tissues, were histologically investigated. These placentas were histologically classified as follows: 51 partial hydatidiform moles (PM), two hydropic abortuses and nine non-hydropic placentas. The DNA indices of the triploid peaks were between 1.41 and 1.60. Histologically, two populations of normal and edematous villi, vesicular villous edema with cistern formation, focal syncytiotrophoblastic hyperplasia with vacuola-tion, and villous scalloping with trophoblastic inclusion were almost always observed in the PM, but no single pathologic feature was specific for PM. The two entities, PM and triploid placenta, overlapped. Not all triploid gestations are PM and not all PM moles are triploid as shown in previously reported diploid or tetraploid PM. Although no patient with triploid PM developed persistent disease in this series, follow up of triploid PM is required as long as its true biological potential remains unclear. Flow cytometry is a reliable aid in the diagnosis of PM.  相似文献   
14.
It is well known that physical exercise can reduce coronary risk factors. But how an aerobic exercise modifies coronary risk factors in relation to severity and physical fitness is still controversial. Fifty-four middle-aged women (mean age, 55 years) completed a 6-month on-site and home-based anaerobic threshold-level exercise program. The changes in coronary risk factor profiles were observed during the pre-intervention and intervention periods. Before the intervention (during control period), most coronary risk factors showed a rather unfavorable trend. After the program, their mean body weight decreased from 56.7 to 55.7 kg (p>0.05) and the proportion of body fat from 30.9 to 27.9% (p>0.05) without any reduction in lean body mass. Systolic blood pressure (SBP) decreased from 129.0 to 125.0 mm Hg (p>0.05) and diastolic blood pressure from 79.5 to 76.6 mm Hg (p>0.05). Fasting plasma glucose (FPG) declined from 109.6 to 103.4 mg/dl (p>0.05). Changes in SBP and FPG were most remarkable in their respective worst tertile. Serum lipids improved only modestly. Maximum oxygen uptake increased from 23.6 to 26.1 ml/kg/min (p>0.01). However, no significant correlations were found between changes in coronary risk factors and those in physical fitness. We conclude that the 6-month aerobic exercise program would modify women’s coronary risk factors depending on their initial values, probably independently of the changes in physical fitness.  相似文献   
15.
Objective To investigate the relation between placental embolisation and the diastolic notch in the uterine artery flow velocity waveform of pregnant ewes under general anaesthesia.
Methods Seven pregnant ewes at a gestation 16 to 17 weeks were anaesthesized and micro beads of gelfoam were injected into the uterine artery; changes in the uterine circulation were assessed by Doppler velocimetry.
Results Gelfoam embolisation reduced uterine blood flow in a dose-dependent manner, from a mean (95% CI) of 568 mL/min (495–641) to 159 mL/min (131–187) after the injection of 30 mg of gelfoam, and increased the uterine vascular resistance from 135 mmHg mine L−1 (103–167) to 498 mmHg mino L−1 (422–574). A diastolic notch in uterine artery flow velocity waveform was observed after 20 mg to 25 mg of gelfoam in two ewes and after injection of 30 mg of gelfoam in all seven animals. Injection of 30 mg of gelfoam increased the pulsatility index to 2–4 (1.9–2.9) from 0.6 (0.5–0.7). The mean uterine vascular resistance at the time of the appearance of a diastolic notch was 414 mmHg mine L−1 (377–451).
Conclusion These findings suggest that an elevated pulsatility index and the presence of a diastolic notch in the uterine artery flow velocity waveform are indicators of increased uterine vascular resistance and impaired uterine circulation.  相似文献   
16.
PURPOSE: Squamous cell carcinoma (SCC) and adenocarcinoma of the lung are currently subject to similar treatment regimens despite distinct differences in histology and epidemiology. The aim of this study is to identify a molecular target with diagnostic and therapeutic values for SCC. EXPERIMENTAL DESIGN: Genes specifically up-regulated in SCC were explored through microarray analysis of 5 SCCs, 5 adenocarcinomas, 10 small cell lung carcinomas, 27 normal tissues, and 40 cancer cell lines. Clinical usefulness of these genes was subsequently examined mainly by immunohistochemical analysis. RESULTS: Seven genes, including aldo-keto reductase family 1, member B10 (AKR1B10), were identified as SCC-specific genes. AKR1B10 was further examined by immunohistochemical analysis of 101 non-small cell lung carcinomas (NSCLC) and its overexpression was observed in 27 of 32 (84.4%) SCCs and 19 of 65 (29.2%) adenocarcinomas. Multiple regression analysis showed that smoking was an independent variable responsible for AKR1B10 overexpression in NSCLCs (P < 0.01) and adenocarcinomas (P < 0.01). AKR1B10 staining was occasionally observed even in squamous metaplasia, a precancerous lesion of SCC. CONCLUSION: AKR1B10 was overexpressed in most cases with SCC, which is closely associated with smoking, and many adenocarcinoma cases of smokers. These results suggest that AKR1B10 is a potential diagnostic marker specific to smokers' NSCLCs and might be involved in tobacco-related carcinogenesis.  相似文献   
17.
PURPOSE: We present results of patients with hepatocellular carcinoma (HCC) treated with proton beam therapy. EXPERIMENTAL DESIGN: We reviewed 162 patients having 192 HCCs treated from November 1985 to July 1998 by proton beam therapy with or without transarterial embolization and percutaneous ethanol injection. The patients in the present series were considered unsuitable for surgery for various reasons, including hepatic dysfunction, multiple tumors, recurrence after surgical resection, and concomitant illnesses. The median total dose of proton irradiation was 72 Gy in 16 fractions over 29 days. RESULTS: The overall survival rate for all of the 162 patients was 23.5% at 5 years. The local control rate at 5 years was 86.9% for all 192 tumors among the 162 patients. The degree of impairment of hepatic functions attributable to coexisting liver cirrhosis and the number of tumors in the liver significantly affected patient survival. For 50 patients having least impaired hepatic functions and a solitary tumor, the survival rate at 5 years was 53.5%. The patients had very few acute reactions to treatments and a few late sequelae during and after the treatments. CONCLUSIONS: Proton beam therapy for patients with HCC is effective, safe, well tolerable, and repeatable. It is the useful treatment mode for either cure or palliation for patients with HCC irrespective of tumor size, tumor location in the liver, insufficient feeding of the tumor with arteries, presence of vascular invasion, impaired hepatic functions, and coexisting intercurrent diseases.  相似文献   
18.
Little is known about the participation rate of newly implemented colorectal cancer (CRC) screening programs in China. Our goals were to identify factors associated with nonparticipation for CRC screening in Songjiang District, Shanghai.We analyzed individuals included in an observational cohort study from 4 towns (Xin Qiao, She Shan, Mao Gang, and Zhong Shan) in Songjiang District. The participation rate was calculated for the CRC screening program based on a fecal immunochemical test and a risk assessment questionnaire between 2015 and 2017 inclusive.Of the 27,130 individuals eligible for inclusion in this study, 20,863 (76.9%) participated in CRC screening at least once during 2015 and 2017. The factors linked with nonparticipation were; being male (odds ratio [OR] 0.87, 95% confidence interval [CI] 0.82–0.93, P < .01), unmarried (OR 0.71, 95% CI 0.64–0.80, P < .01), having a high education level (middle school, OR 0.82, 95% CI 0.74–0.90, P < .01, high school or above, OR 0.64, 95% CI 0.57–0.73, P < .01), absence of chronic disease (OR 0.90, 95% CI 0.85–0.96, P < .01), and living in 2 out of the 4 towns covered (Xin Qiao, OR 0.72, 95% CI 0.66–0.78, P < .01, Zhong Shan, OR 0.29, 95% CI 0.26–0.31, P < .01).The current study revealed several associated factors with nonparticipation for the CRC screening in Songjiang district. These findings will help identify target populations that require an individualized approach to increase the participation rate.  相似文献   
19.
BACKGROUND: Peripheral blood stem cell (PBSC) reinfusion has been widely used for hematopoietic reconstitution after high-dose chemotherapy. However, the optimal dose of granulocyte colony-stimulating factor (G-CSF) for PBSC mobilization in combination with chemotherapy for autograft remains unknown. METHODS: To find the optimal dose of glycosylated G-CSF (lenograstim) for PBSC mobilization in combination with chemotherapy for aggressive non-Hodgkin's lymphoma (NHL), we conducted a dose-finding study on 43 newly diagnosed patients who had unfavorable prognostic factors. They received four to six courses of cyclophosphamide, doxorubicin, vincristine and prednisolone combined with lenograstim every 2 weeks (biweekly CHOP therapy). PBSC apheresis was started after the third course of biweekly CHOP therapy. Lenograstim was given daily from day 3 until the day of the last apheresis. The optimum dose of lenograstim was assessed based on mobilization efficacy and safety profiles at a daily single dose of 2, 5 and 10 microg/kg for eight patients in each level. RESULTS: The collected number of CD34+ cells in the first apheresis products was higher in the 5 microg/kg group than in the 2 microg/kg group (median, 4.22 x 10(6) vs 2.49 x 10(6) CD34+ cells/kg, P = 0.051). The highest dose of 10 microg/kg (median, 2.99 x 10(6) CD34+ cells/kg) failed to show a dose dependence in PBSC mobilization. The efficacy and safety of the 5 microg/kg dose were further confirmed in an additional 19 patients. CONCLUSIONS: The present study suggests that the recommended dose of lenograstim for PBSC mobilization with CHOP therapy in untreated NHL is 5 microg/kg.  相似文献   
20.
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