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   16217篇
  免费   842篇
  国内免费   104篇
耳鼻咽喉   89篇
儿科学   408篇
妇产科学   252篇
基础医学   1862篇
口腔科学   303篇
临床医学   993篇
内科学   4407篇
皮肤病学   437篇
神经病学   1155篇
特种医学   555篇
外科学   3090篇
综合类   89篇
预防医学   396篇
眼科学   119篇
药学   987篇
中国医学   31篇
肿瘤学   1990篇
  2023年   124篇
  2022年   239篇
  2021年   423篇
  2020年   255篇
  2019年   339篇
  2018年   379篇
  2017年   306篇
  2016年   351篇
  2015年   404篇
  2014年   502篇
  2013年   566篇
  2012年   1036篇
  2011年   1062篇
  2010年   616篇
  2009年   509篇
  2008年   885篇
  2007年   944篇
  2006年   991篇
  2005年   919篇
  2004年   947篇
  2003年   916篇
  2002年   943篇
  2001年   294篇
  2000年   225篇
  1999年   273篇
  1998年   223篇
  1997年   191篇
  1996年   160篇
  1995年   131篇
  1994年   118篇
  1993年   96篇
  1992年   154篇
  1991年   150篇
  1990年   166篇
  1989年   125篇
  1988年   141篇
  1987年   153篇
  1986年   134篇
  1985年   134篇
  1984年   103篇
  1983年   67篇
  1982年   38篇
  1981年   35篇
  1980年   32篇
  1979年   55篇
  1978年   33篇
  1977年   32篇
  1975年   26篇
  1974年   27篇
  1971年   28篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
BACKGROUND: The aim of this study was to identify the independent histopathologic prognostic factors for patients with cervical carcinoma treated with radical hysterectomy including paraaortic lymphadenectomy. METHODS: A total of 187 patients with stage IB to IIB cervical carcinomas treated with radical hysterectomy and systematic retroperitoneal lymphadenectomy were retrospectively analyzed. The median follow-up period was 83 months. Cox regression analysis was used to select independent prognostic factors. RESULTS: Using multivariate Cox regression analysis, lymph node (LN) status (negative vs. metastasis to pelvic nodes except for common iliac nodes vs. common iliac/paraaortic node metastasis), histopathologic parametrial invasion, lymph-vascular space invasion (LVSI), and histology of pure adenocarcinoma were found to be independently related to patients' poor survival. For patients who had a tumor histologically confined to the uterus and have neither parametrial invasion nor lymph node metastasis, LVSI was the most important prognostic factor, and histologic type, depth of cervical stromal invasion, and tumor size were not related to survival. The survival of patients with a tumor extending to parametrium or pelvic lymph node(s) was adversely affected by histology of pure adenocarcinoma. When the tumor extended to common iliac or paraaortic nodes, patients' survival became quite poor irrespective of LVSI or histologic type of pure adenocarcinoma. Patients' prognosis could be stratified into low risk (patients with a tumor confined to the uterus not associated with LVSI: n = 80), intermediate risk (patients with a tumor confined to the uterus associated with positive LVSI, and patients with squamous/adenosquamous carcinoma associated with pelvic lymph node metastasis or parametrial invasion: n = 86), and high risk (patients with pure adenocarcinoma associated with pelvic lymph node metastasis or parametrial invasion, and patients with common iliac/paraaortic node metastasis: n = 21) with an estimated 5-year survival rate of 100 +/- 0 (mean +/- SE)%, 85.5 +/- 3.9%, and 25.1 +/- 9.7%, respectively. CONCLUSIONS: LN status, parametrial invasion, LVSI, and histology of pure adenocarcinoma are important histopathologic prognostic factors of cervical carcinoma treated with radical hysterectomy and systematic retroperitoneal lymphadenectomy. Prognosis for patients with cervical carcinoma may be stratified by combined analysis of these histopathologic prognostic factors. Postoperative therapy needs to be individualized according to these prognostic factors and validated for its efficacy using randomized clinical trials.  相似文献   
982.
We report here a case with severe intrauterine growth restriction from the first trimester and clinical features of Silver-Russell syndrome including microcephaly, low-set ear, atrial septum defect, ventricular septum defect, diaphragmatic relaxation, and rocker bottom feet. Silver-Russell syndrome is thought to result from deletion of the distal long arm of chromosome 15 on which the IGF-I receptor (IGF-IR) gene is located. We measured both the maternal and cord blood levels of GH, IGF-I, and IGF-binding protein and performed an immunohistochemical study of IGF-IR in the placenta to investigate whether these IGF-related proteins were affected in this patient. The hormonal level of these proteins did not significantly differ from normal neonates, and immunohistochemical analysis suggested IGF-IR protein levels in the placenta were comparable to normal term neonates. These results support the hypothesis that growth insufficiency could occur in patients with monosomy of the distal long arm of chromosome 15 and suggest a critical threshold for IGF-related fetal growth in early pregnancy.  相似文献   
983.
984.
Maternal sepsis is an unusual but catastrophic complication of amniocentesis. We report a case of successful treatment of maternal septic shock and multiple organ failure following amniocentesis at midgestation, possibly due to needle puncture of the sigmoid colon, which was tightly adherent to the anterior surface of the pregnant uterus.  相似文献   
985.
This study aimed to investigate the suitability of using ultrasonograph muscle thickness (MT) measurements to estimate the muscle volume (MV) of the quadriceps femoris as an alternative approach to magnetic resonance imaging (MRI). The subjects were 46 men aged from 20 to 70 years who were randomly allocated to either a validation or a cross-validation group. In the validation group, multiple and simple regression equations, which used a set of MT values determined at mid-thigh and thigh length (l) and the product of π, (MT/2)2, and l [π·(MT/2)2·l], respectively, as independent variables, were derived to estimate the MV measured by MRI. Because the two equations were cross-validated, the data from the two groups were pooled to generate the final prediction equations: MV (cm3)=(MT×311.732)+(l×53.346) –2058.529 as the multiple regression equation and MV (cm3)=[π·(MT/2)2·l]×1.1176+663.040 as the simple regression equation. In the multiple regression equation, MT explained 75% of the variation in the MV measured by MRI. The r 2 and the standard error of the estimate (SEE) of the equations were 0.824 and 175.6 cm3 (10.6%), respectively, for the multiple regression equation and 0.829 and 173.7 cm3 (10.5%), respectively, for the simple regression equation. Thus, the present results indicate that ultrasonograph MT measurements at mid-thigh are useful for estimating the MV of knee extensors. However, the observed SEE values suggest that the prediction equation obtained in this study may be limited to population studies rather than individual assessments in longitudinal studies. Electronic Publication  相似文献   
986.
We have previously shown that stool concentrations of decay-accelerating factor (DAF; CD55), a membrane-bound complement-regulatory protein, are significantly elevated in patients with colorectal cancer and that the measurement of stool DAF may be a valuable test for the detection of colorectal cancer. Accordingly, we are working to develop a clinically useful immunoassay for fecal DAF. A requirement for such assay is a plentiful and reliable supply of anti-DAF antibodies. We developed a sandwich enzyme-linked immunosorbent assay (ELISA) for DAF in stool specimens, using two monoclonal anti-DAF antibodies recognizing different epitopes on the DAF molecule. When we first used a biotin-labeled antibody and enzyme-linked streptavidin method, we often observed stool interference, probably due to the presence of a substance(s) with biotin activity which non-specifically bound to the Fc portion of IgG of the first anti-DAF antibody on the ELISA wells. By the use of inorganic salts in the sample-dilution buffer and HRP-labeled anti-DAF as second antibody, we circumvented the stool interference and established that the new ELISA system could reliably measure DAF at low concentrations in stool specimens. Because the new assay system uses only monoclonal antibodies, we can now consistently supply ample amounts of antibodies for routine measurement of stool DAF.  相似文献   
987.
There is considerable interest in structured treatment interruption(STI), which has been stimulated by certain evidence that treatment interruption may boost the infected individual's immune response to HIV-1. There are several distinct settings where STI may be instituted: (i) STI for those with acute HIV-1 infection, (ii) STI for those with chronic infection, and (iii) STI before switching drugs. A number of STI protocols have been evaluated and certain promising results have been reported in certain groups of HIV-1-infected individuals while viral rebound as the consequence of interruption has been seen in other patients and drug failure to re-suppress HIV-1 upon re-starting therapy, STI-associated CD4+ cell decline and viral drug resistance emergence have been serious concern. Currently, STI cannot be recommended in clinical settings. Randomized, controlled trials to determine the applicability of STI for therapy of HIV-1 infection are required.  相似文献   
988.
989.
The etiology of congenital hypothyroidism (CH) may play an important role in determining disease severity, outcome, and, therefore, its treatment schedule. Radionuclide imaging (RI) is currently the most precise diagnostic technique to establish the etiology of CH. Conventional ultrasound can identify an athyrotic condition at the normal neck position and has gained acceptance for the initial evaluation of CH; however, its ability in delineating ectopic thyroid is limited. We used color Doppler ultrasonography (CDU) to assess blood flow and morphology in the detection of ectopic thyroid in 11 CH patients disclosed by neonatal screening; thyroid glands were undetectable at the normal location by gray-scale ultrasonography (GSU). The patients studied consisted of two infants for initial investigation and nine children for reevaluating the cause of CH. All of the patients underwent GSU, CDU, RI, and magnetic resonance imaging (MRI) investigation. We set RI as the defining diagnostic test for detecting ectopic thyroid and compared the imaging of CDU with those of GSU and MRI. The results of RI showed 10 ectopic thyroids and one athyreosis. In the patients with ectopic thyroid, the sensitivity of CDU, GSU, and MRI for detecting ectopic thyroid was 90, 70, and 70%, respectively. We conclude that CDU is superior to GSU and MRI for detecting ectopic thyroid and that CDU may be adopted as the diagnostic tool for the initial investigation of suspected CH.  相似文献   
990.
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