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   5419篇
  免费   466篇
  国内免费   9篇
耳鼻咽喉   82篇
儿科学   105篇
妇产科学   164篇
基础医学   687篇
口腔科学   105篇
临床医学   724篇
内科学   1003篇
皮肤病学   77篇
神经病学   372篇
特种医学   220篇
外科学   651篇
综合类   133篇
一般理论   1篇
预防医学   657篇
眼科学   51篇
药学   427篇
中国医学   14篇
肿瘤学   421篇
  2023年   36篇
  2022年   83篇
  2021年   128篇
  2020年   76篇
  2019年   106篇
  2018年   97篇
  2017年   88篇
  2016年   83篇
  2015年   103篇
  2014年   152篇
  2013年   180篇
  2012年   321篇
  2011年   342篇
  2010年   154篇
  2009年   156篇
  2008年   225篇
  2007年   281篇
  2006年   293篇
  2005年   249篇
  2004年   244篇
  2003年   220篇
  2002年   175篇
  2001年   137篇
  2000年   146篇
  1999年   123篇
  1998年   60篇
  1997年   54篇
  1996年   39篇
  1995年   46篇
  1993年   40篇
  1992年   111篇
  1991年   101篇
  1990年   79篇
  1989年   72篇
  1988年   84篇
  1987年   81篇
  1986年   72篇
  1985年   80篇
  1984年   53篇
  1983年   52篇
  1982年   36篇
  1981年   33篇
  1980年   43篇
  1979年   51篇
  1978年   32篇
  1976年   32篇
  1975年   34篇
  1974年   37篇
  1971年   31篇
  1970年   33篇
排序方式: 共有5894条查询结果,搜索用时 0 毫秒
41.
OBJECTIVE: Antenatal perineal massage has been shown to reduce the incidence of perineal tears in primiparous women. The aim of this study was to determine whether perineal massage impacts on primary prevention of symptomatic disruption of the fecal continence mechanism. METHODS: An observational study recruited two cohorts of women. The first, massage group (MG) chose to perform daily perineal massage from 34 weeks gestation, and the second, control group (CG) was asked to avoid massage. Perineal injury and postnatal pain were documented and all women were invited to attend at three months postpartum for continence assessment, anal manometry, and endoanal ultrasound. RESULTS: Of 179 women recruited, 100 were in the MG while 79 women were controls. Mode of delivery was not influenced by perineal massage. Although the impact did not reach statistical significance, women aged over 30 years in the MG were more likely to be delivered with an intact perineum than controls. Postnatal perineal pain was much reduced in the MG compared with the CG (p = 0.029). Of the women recruited, 136 (75.9%) returned for a postnatal continence assessment. Manometry pressures, continence scores, and endoanal ultrasound findings were similar in both groups. CONCLUSION: Antenatal perineal massage was found to significantly affect postnatal perineal pain scores although it did not impact on the incidence of intact perineum at delivery, postnatal continence scores, anal manometry pressures, or endoanal ultrasound findings.  相似文献   
42.
(1) The methylxanthine caffeine has many pharmacological effects, most of which can be linked to blockade of adenosine receptors, inhibition of phosphodiesterases, and augmentation of calcium-dependent release of calcium from intracellular stores. (2) A variety of xanthines have been developed as potent and/or selective antagonists for adenosine receptors. (3) Several xanthines have been developed that are more potent and more selective inhibitors of cyclic nucleotide phosphodiesterase than caffeine or theophylline. (4) Caffeine remains the xanthine of choice for activation of intracellular calcium-sensitive calcium release channels although millimolar concentrations are required, which can have effects on other aspects of calcium regulation.  相似文献   
43.
IntroductionGrowing interest surrounds the concept of en bloc transurethral resection of bladder tumors (ERBT). Theoretical advantages include improved adherence to oncological principles and potential yield of superior pathological specimens. Multiple ERBT methods exist. This review summarizes the current evidence regarding application of differing techniques and technologies to ERBT.MethodsA systematic review of MEDLINE/EMBASE/Scopus databases was performed, using terms “en bloc,” “ERBT,” “bladder,” and “urinary bladder neoplasm.” Template-based data extraction included technique of ERBT, feasibility, tumor size, activation of obturator nerve reflex, operative complications, detrusor muscle sampling rate, and recurrence data.ResultsMultiple approaches to ERBT have evolved, using a variety of energy sources. The feasibility of electrocautery, laser, combined waterjet/electrocautery, and polypectomy snare techniques have been confirmed in achieving ERBT. ERBT appears safe, with a low complication rate. The use of laser energy sources reduces the risk of activating the obturator nerve reflex during lateral wall resections. Otherwise, no energy source is unequivocally superior in achieving ERBT. The rate of detrusor muscle sampling is high with use of ERBT and appears superior to that achieved with conventional TURBT (cTURBT) in multiple comparative studies. A limited number of largely non-randomized trials assess bladder tumor recurrence; current evidence suggests this is similar between ERBT and cTURBT groups.ConclusionsERBT using a variety of technologies is feasible and safe, with a high detrusor muscle sampling rate. Further research is required to determine whether rates of residual disease or recurrence can be reduced with ERBT vs. cTURBT.  相似文献   
44.
45.
Mononuclear cells from 15 patients with hairy cell leukemia were studied before and during therapy with interferon alfa-2b (IFN) by regular peripheral blood differential counts and flow cytometry, using a panel of monoclonal antibodies (Moab). Seven leukemic phase patients (Group 1) had a mean leukocyte count of 48,870/microliter at entry with a mean absolute hairy cell (HC) count of 40,100/microliter. After 3 months on IFN, both parameters decreased significantly (WBC 3,500/microliter; HC count 130/microliter). In eight patients with a cytopenic form of the disease (Group 2) the mean leukocyte count rose from 2950/microliter to 3890/microliter while the mean absolute HC count decreased from 300/microliter to 120/microliter. The morphologic shifts correlated well with changes in the Moab reaction pattern. In Group 1 the activity of all Moab decreased significantly. In Group 2, only cells expressing Leu 3a and Leu 11a (a marker of natural killer cells) showed a significant shift, the latter increasing from 170/microliter to 360/microliter. This increase in natural killer cell antigen expression was not obvious based on routine morphologic observations alone. We show that flow cytometry may be a useful adjunct in monitoring the response of HCL to therapy. Changes in populations of cells that may be difficult to discriminate on morphologic grounds alone may be observed.  相似文献   
46.
47.
48.
In this report, we describe a national-scale monitoring of the SARS-CoV-2 (SC-2) variant dynamics in Israel, using multiple-time sampling of 13 wastewater treatment plants. We used a combination of inclusive and selective quantitative PCR assays that specifically identify variants A19/A20 or B.1.1.7 and tested each sample for the presence and relative viral RNA load of each variant. We show that between December 2020 and March 2021, a complete shift in the SC-2 variant circulation was observed, where the B.1.1.7 replaced the A19 in all examined test points. We further show that the normalized viral load (NVL) values and the average new cases per week reached a peak in January 2021 and then decreased gradually in almost all test points, in parallel with the progression of the national vaccination campaign, during February–March 2021. This study demonstrates the importance of monitoring SC-2 variant by using a combination of inclusive and selective PCR tests on a national scale through wastewater sampling, which is far more amendable for high-throughput monitoring compared with sequencing. This approach may be useful for real-time dynamics surveillance of current and future variants, such as the Omicron (BA.1, BA.2) and other variants.  相似文献   
49.
ECG-gated cardiac CT   总被引:12,自引:0,他引:12  
  相似文献   
50.
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