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   2520篇
  免费   229篇
  国内免费   3篇
耳鼻咽喉   14篇
儿科学   108篇
妇产科学   41篇
基础医学   291篇
口腔科学   72篇
临床医学   223篇
内科学   495篇
皮肤病学   35篇
神经病学   264篇
特种医学   140篇
外科学   264篇
综合类   52篇
一般理论   3篇
预防医学   330篇
眼科学   22篇
药学   158篇
中国医学   4篇
肿瘤学   236篇
  2021年   21篇
  2020年   17篇
  2019年   26篇
  2018年   27篇
  2017年   31篇
  2016年   31篇
  2015年   39篇
  2014年   72篇
  2013年   82篇
  2012年   120篇
  2011年   121篇
  2010年   81篇
  2009年   70篇
  2008年   125篇
  2007年   132篇
  2006年   111篇
  2005年   90篇
  2004年   93篇
  2003年   62篇
  2002年   103篇
  2001年   82篇
  2000年   83篇
  1999年   90篇
  1998年   39篇
  1997年   32篇
  1996年   53篇
  1995年   49篇
  1994年   26篇
  1993年   25篇
  1992年   62篇
  1991年   43篇
  1990年   60篇
  1989年   51篇
  1988年   42篇
  1987年   37篇
  1986年   40篇
  1985年   41篇
  1984年   33篇
  1983年   25篇
  1982年   28篇
  1981年   23篇
  1980年   28篇
  1979年   29篇
  1978年   25篇
  1977年   26篇
  1976年   21篇
  1974年   26篇
  1973年   16篇
  1970年   14篇
  1969年   15篇
排序方式: 共有2752条查询结果,搜索用时 15 毫秒
1.
2.
Prostatitis accounts for almost 2 million office visits to urologists and primary care physicians. The label “prostatitis” refers to a diverse constellation of symptoms and disease processes. The diagnosis and treatment of this disorder present numerous challenges for the physician, including a lack of abnormal findings on physical examination, laboratory tests, and radiographic images. In this article, we offer a review of the current literature and recommendations for the evaluation and diagnosis of the patient presenting with prostatitis.  相似文献   
3.
Catastrophic failure of two zirconia—ceramic modular femoral heads occurred, despite the theoretical improved toughness of zirconia—ceramic relative to alumina—ceramic. This experience led the authors to return to cobalt—chromium as the metal of choice for articulation against polyethylene in total hip arthroplasty.  相似文献   
4.
Localized 1H NMR spectra of glutamate in the human brain.   总被引:2,自引:0,他引:2  
Localized 1H NMR spectra at TE = 12 ms were obtained from cerebral cortex of human subjects using ISIS with surface suppression. The 2.29-ppm resonance was assigned to C4 glutamate with contributions from C4 glutamine and GABA using in vivo spectral editing and comparison of chemical shift with pure compounds. The measured intensity ratio between the 2.29 resonance and the creatine resonance at 3.03 ppm was in good agreement with the ratio predicted from previously reported measurements of glutamate, glutamine, and GABA concentrations in biopsied human brain tissue.  相似文献   
5.
Even though continued smoking by cancer patients adversely affects survival and quality of life, about one third of patients who smoked prior to their diagnosis continue to smoke after their diagnosis. The implementation of smoking cessation treatments for cancer patients has been slowed by the lack of data on correlates of tobacco use in this population. Thus, this longitudinal study assessed demographic, medical, addiction, and psychological predictors of tobacco use among 74 head, neck, and lung cancer patients. Multivariable binary logistic regression analyses, with outcome categorized as smoker or nonsmoker, indicated that the likelihoodthat patients would be a smoker was associated with lower levels of perceived risk and a higher level of quitting cons. Multivariable nominal logistic regression, with outcome classified as continuous smoker, continuous quitter, relapser, or follow-up quitter, indicated that: (a) patients categorized as continuous smokers reported significantly lower quitting self-efficacy than follow-up quitters and continuous quitters, (b) relapsers reported a significantly lower level of quitting self-efficacy than either follow-up quitters or continuous quitters, and (c) continuous smokers exhibited a significantly lower level of risk perceptions than continuous abstainers. These findings can be useful for the development and evaluation of treatments to promote smoking cessation among cancer patients. Support for this study was provided by National Institutes of Health Grants CA57708, CA06927, CA88610, CA95678, and CA76644.  相似文献   
6.
7.
One of the most exciting developments in pediatric dermatology has been the use of the flashlamp-pumped, 585-nm, pulsed dye laser for treatment of vascular birthmarks. In many cases the results are miraculous. The increase in self-esteem and happiness of many children and adolescents has been overwhelming; for some, depression has been lifted, stuttering has ceased, social involvement has increased, and antidepressants have been discontinued. There are many success stories to tell.
Despite the remarkable effects of the pulsed dye laser and the medical and psychosocial indications for its use, the issue of pain control remains significant. We have no perfect outpatient pediatric anesthetic. Most methods carry either some risk or, if not hazardous, often are not very effective for controlling pain. Needless to say, a diversity of opinions exist on how to manage discomfort from this treatment modality. Therefore, we thought it would be useful to share the experiences and opinions of several dermatologists who have extensive experience with the pulsed dye laser.  相似文献   
8.
We have performed a medialization laryngoplasty on a schoolteacher who was also an amateur singer. Medialization laryngoplasty has been slow to gain acceptance but offers many advantages over Teflon injection because it is a reversible procedure and can be utilized early in vocal cord paralysis instead of waiting 9 months. Postoperatively, the patient can vocalize more than two octaves with good volume. Objective measurements of results is needed in judging the success of these procedures.  相似文献   
9.
Thrombospondin (TSP), a large glycoprotein present in platelets, and various normal and tumor tissues, has recently been shown to promote cell adhesion and platelet aggregation. Most importantly because TSP has been shown to promote metastasis of melanoma tumor cells to the lung in a murine model (1) and since thromboembolic events commonly occur in patients afflicted with metastatic tumors, we explored the role of TSP in human cancer by measuring TSP blood levels in patients with various malignant neoplasms. Blood TSP levels were measured by indirect enzyme-linked immunoadsorbent assay (ELISA) from 20 control subjects, 22 patients with gastrointestinal (GI) cancer, 18 patients with breast cancer, and 17 patients with lung cancer. Control subjects consisted both of healthy subjects and acutely ill patients with no malignancies. TSP levels of both healthy and acutely ill controls were found to range between 245-440 ng/ml with a mean of 365 ng/ml. In contrast, elevated levels of TSP greater than the mean value of 400 ng/ml for controls ranging between 590-3,650 ng/ml were found in 20/22 (91%) patients with GI malignancies, 13/18 (72%) patients with breast cancer, and 15/17 (88%) with lung cancer. Mean TSP levels of GI, breast, and lung cancer patients were 3, 2, and 3 fold greater than controls, respectively. Increased blood TSP levels in patients were not due to increased levels of platelets since both control and patient groups had platelet counts within the normal range. These results suggest that TSP may play a role in tumor cell metastasis in man and could serve as a blood marker for metastasis.  相似文献   
10.
Changes in cerebral blood flow (CBF), volume (CBV), and oxygenation (blood-oxygenation level dependent (BOLD)) during functional activation are important for calculating changes in cerebral metabolic rate of oxygen consumption (CMRo2) from calibrated functional MRI (fMRI). An important part of this process is the CBF/CBV relationship, which is signified by a power-law parameter: gamma=ln (1+DeltaCBV/CBV)/ln (1+DeltaCBF/CBF). Because of difficulty in measuring CBF and CBV with MRI, the value of gamma is therefore assumed to be approximately 0.4 from a prior primate study under hypercapnia. For dynamic fMRI calibration, it is important to know if the value of gamma varies after stimulation onset. We measured transient relationships between DeltaCBF, DeltaCBV, and DeltaBOLD by multimodal MRI with temporal resolution of 500 ms (at 7.0 T) from the rat somatosensory cortex during forepaw stimulation, where the stimulus duration ranged from 4 to 32 secs. Changes in CBF and BOLD were measured before the administration of the contrast agent for CBV measurements in the same subjects. We observed that the relationship between DeltaCBF and DeltaCBV varied dynamically from stimulation onset for all stimulus durations. Typically after stimulation onset and at the peak or plateau of the DeltaCBF, the value of gamma ranged between 0.1 and 0.2. However, after stimulation offset, the value of gamma increased to 0.4 primarily because of rapid and slow decays in DeltaCBF and DeltaCBV, respectively. These results suggest caution in using dynamic measurements of DeltaCBF and DeltaBOLD required for calculating DeltaCMRo2 for functional stimulation, when either DeltaCBV has not been accurately measured or a fixed value of gamma during hypercapnia perturbation is used.  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