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   3216篇
  免费   224篇
  国内免费   10篇
耳鼻咽喉   20篇
儿科学   115篇
妇产科学   101篇
基础医学   386篇
口腔科学   73篇
临床医学   319篇
内科学   778篇
皮肤病学   79篇
神经病学   189篇
特种医学   68篇
外科学   404篇
综合类   80篇
一般理论   6篇
预防医学   231篇
眼科学   85篇
药学   278篇
中国医学   14篇
肿瘤学   224篇
  2024年   5篇
  2023年   32篇
  2022年   95篇
  2021年   163篇
  2020年   88篇
  2019年   135篇
  2018年   176篇
  2017年   84篇
  2016年   107篇
  2015年   96篇
  2014年   141篇
  2013年   204篇
  2012年   273篇
  2011年   213篇
  2010年   141篇
  2009年   119篇
  2008年   170篇
  2007年   197篇
  2006年   188篇
  2005年   150篇
  2004年   135篇
  2003年   104篇
  2002年   83篇
  2001年   33篇
  2000年   36篇
  1999年   29篇
  1998年   14篇
  1997年   15篇
  1996年   13篇
  1995年   4篇
  1994年   8篇
  1993年   8篇
  1992年   20篇
  1991年   15篇
  1990年   16篇
  1989年   8篇
  1988年   13篇
  1987年   13篇
  1986年   15篇
  1985年   18篇
  1984年   6篇
  1983年   7篇
  1981年   10篇
  1980年   7篇
  1979年   6篇
  1978年   4篇
  1976年   3篇
  1973年   8篇
  1972年   3篇
  1971年   5篇
排序方式: 共有3450条查询结果,搜索用时 515 毫秒
31.

Exceptional precautionary measures have been adopted to stop the transmission and control of COVID-19 through the world and Pakistan is facing lockdown in this scenario. Public loyalty to precautionary measures is affected by their knowledge, attitude, risk factors and practices (KAP) towards COVID-19. The present study was conducted among the Pakistani residents to observe the knowledge, attitude, practices and risk factors towards COVID-19 outbreak in Pakistan. A questionnaire was designed, and a cross-sectional survey was conducted among participants of the study area. Participants were asked the questions regarding knowledge, attitude, practices and risk factors towards COVID-19. Data were analyzed by SPSS and t/F test and correlation was applied among the knowledge, attitude, risk factors and practices. A total of 1060 questionnaires were received. 1004 were included while 56 were excluded. The highest representation was from Punjab province (65.6%), female (63%) and age group of 21–30 years (62.1%). Most participants were single (85%), Muslim (99.4%), Urdu speaking (45.6%) and were graduates (51.5%). Most of the participants were students (52.9%) and were from economically middle-class families (40.8%). The knowledge was positively correlated with attitude and practices whereas negatively correlated with risk factors (P?<?0.05). The attitude was negatively correlated with risk factor and positively correlated with practices. The risk factors and practices were positively correlated with each other. Health education program to improve the COVID-19 knowledge, attitude, practices and risk factors should be initiated to combat current health challenge.

  相似文献   
32.
STUDY DESIGN: A correlative design using stepwise regression analysis. OBJECTIVE: To explore the variation in spinal isometric strength that can be accounted for by anticipation of pain, sensory perception of pain, functional disability belief, and the fear-avoidance belief in chronic low back pain patients. SUMMARY OF THE BACKGROUND DATA: Several biobehavioral factors contribute to the persistence of pain behavior in chronic patients. Recent studies suggest a need to explore the relation between reduced physical performance and the sensory and cognitive perception of pain. METHODS: Sixty-three patients with chronic low back pain 20 to 56 years of age participated in this study. Visual Analogs Scales, the Fear-Avoidance Belief questionnaire, and the Disability Belief questionnaire were used to measure the sensory and cognitive dimensions of pain. Spinal isometric strength was measured by the Medx lumbar extension machine. RESULTS: Analysis of variance and the stepwise regression analysis demonstrated that anticipation of pain and the fear-avoidance belief about physical activity significantly predicted variation in the spinal isometric strength deficit P < 0. 001. True pain experienced during the testing and answers to the Disability Belief questionnaire were not related. CONCLUSION: The results of this study strongly support the hypothesis that spinal physical capacity in chronicity is not explained solely by the sensory perception of pain. The anticipation of pain and the fear-avoidance belief about physical activities were the strongest predictors of the variation in physical performance.  相似文献   
33.
Purpose: The purpose of this study was to evaluate the clinical effectiveness of subcutaneous estradiol pellets in donor oocyte recipients with an inadequate endometrial response. Methods: The subjects were 13 women with ovarian failure and a maximal endometrial thickness <10 mm on standard estrogen regimens, as demonstrated during mock and/or prior oocyte donation cycles. They underwent pellet implantation (100–250 mg of estradiol) 6–13 weeks before oocyte donation. Results: Maximal (mean ± SD) endometrial thickness was 8.7±1.5 mm on standard regimens, in contrast to 11.7± 1.8 mm on pellets, while estradiol levels were 674±844 and 815±706 pg/ml, respectively. The estradiol:estrone ratio on pellets was >1. There was 1 pregnancy with early loss during 10 cycles on other estrogen regimens and 12 pregnancies during 19 cycles on pellets. The pregnancy and implantation rates were, respectively, 63 and 27% on pellets and 41 and 14% on standard regimens in historical controls. Conclusions: We conclude that estradiol pellets after a single administration provide constant estradiol levels extending into the first trimester of pregnancy, a physiologic estradiol:estrone ratio, and a better endometrial response than standard estrogen regimens. Implantation and pregnancy rates are higher. This approach may be especially suitable for recipients with a poor endometrial response. Presented at the IXth World Congress on In Vitro Fertilization and Assisted Reproduction, Vienna, Austria, April 3, 1995, and the 51st Annual Meeting of the American Society for Reproductive Medicine, Seattle, Washington, October 7–12, 1995.  相似文献   
34.
35.
Retroperitoneal fibrosis (RF) is a clinical entity characterized by the progressive proliferation of connective tissue that rarely forms a mass involving the periaortic area of the abdomen, which may be idiopathic as well as a result of an inflammatory process after aneurysmal dilatation of the aorta. This fibrotic tissue may cover both aorta and iliac arteries, reach the retroperitoneum and surrounding ureters, and cause serious obstructions and renal insufficiency in three-quarters of patients. Most of the patients are known to have atherosclerosis and local inflammation against the antigens of the plaques. A systemic autoimmune disease presenting with retroperitoneal fibrosis seems to be pronounced more frequently nowadays because of the elevated acute-phase reactant levels, positive autoantibodies, and concurrent autoimmune diseases affecting other organs in majority of the diagnosed patients. Ultrasonography, computed tomography, magnetic resonance imaging, positron emission tomography, and retroperitoneal biopsy are useful in diagnosing and assessing the full extent of the disease. Surgical interventions such as ureterolysis and aneurysm repair are frequently performed, but medical therapy including steroids and immunosuppressants is often needed because of the inflammatory and chronic-relapsing nature of the disease.

In this paper, we described two cases diagnosed with RF secondary to hemilaminectomy and hypothyroidism, and we summarized the literature related to RF.  相似文献   
36.
In this study, our objective was to determine whether a synergistic antimicrobial combination in vitro would be beneficial in the downregulation of pneumococcal virulence genes and whether the associated inflammation of the lung tissue induced by multidrug-resistant Streptococcus pneumoniae infection in vivo needs to be elucidated in order to consider this mode of therapy in case of severe pneumococcal infection. We investigated in vivo changes in the expression of these virulence determinants using an efficacious combination determined in previous studies. BALB/c mice were infected with 106 CFU of bacteria. Intravenous levofloxacin at 150 mg/kg and/or ceftriaxone at 50 mg/kg were initiated 18 h postinfection; the animals were sacrificed 0 to 24 h after the initiation of treatment. The levels of cytokines, chemokines, and C-reactive protein (CRP) in the serum and lungs, along with the levels of myeloperoxidase and nitric oxide the inflammatory cell count in bronchoalveolar lavage fluid (BALF), changes in pneumolysin and autolysin gene expression and COX-2 and inducible nitric oxide synthase (iNOS) protein expression in the lungs were estimated. Combination therapy downregulated inflammation and promoted bacterial clearance. Pneumolysin and autolysin expression was downregulated, with a concomitant decrease in the expression of COX-2 and iNOS in lung tissue. Thus, the combination of levofloxacin and ceftriaxone can be considered for therapeutic use even in cases of pneumonia caused by drug-resistant isolates.  相似文献   
37.
38.
39.
40.
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