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   777篇
  免费   43篇
  国内免费   17篇
耳鼻咽喉   1篇
儿科学   37篇
妇产科学   7篇
基础医学   97篇
口腔科学   19篇
临床医学   182篇
内科学   124篇
皮肤病学   3篇
神经病学   70篇
特种医学   102篇
外国民族医学   1篇
外科学   56篇
综合类   38篇
预防医学   44篇
眼科学   8篇
药学   31篇
中国医学   1篇
肿瘤学   16篇
  2020年   5篇
  2019年   7篇
  2018年   7篇
  2017年   10篇
  2016年   11篇
  2015年   11篇
  2014年   17篇
  2013年   28篇
  2012年   29篇
  2011年   24篇
  2010年   36篇
  2009年   24篇
  2008年   33篇
  2007年   38篇
  2006年   24篇
  2005年   24篇
  2004年   22篇
  2003年   26篇
  2002年   25篇
  2001年   22篇
  2000年   24篇
  1999年   23篇
  1998年   28篇
  1997年   32篇
  1996年   27篇
  1995年   23篇
  1994年   21篇
  1993年   20篇
  1992年   8篇
  1991年   12篇
  1990年   12篇
  1989年   28篇
  1988年   23篇
  1987年   17篇
  1986年   13篇
  1985年   11篇
  1984年   6篇
  1983年   10篇
  1982年   5篇
  1981年   7篇
  1980年   12篇
  1979年   4篇
  1978年   8篇
  1977年   3篇
  1976年   5篇
  1975年   5篇
  1974年   3篇
  1970年   5篇
  1968年   2篇
  1966年   3篇
排序方式: 共有837条查询结果,搜索用时 15 毫秒
1.
In HIV/AIDS research, few studies to date have evaluated ways to improve parental HIV disclosure practices using feedback from HIV-negative children who have recently experienced this event. We conducted semi-structured in-depth interviews with 20 children (aged 6–15) who were partially to fully aware of their parents’ HIV status in rural Guangxi, China. Of the 20 children, eight children who were of older age (11.38 years in average) endorsed parental HIV disclosure, five discouraged it and seven expressed uncertainty. Children’s different experiences and attitudes towards disclosure were seen to be associated with their family dynamics (especially the parent–child relationship), social support and care, experiences of stigma and discrimination, psychosocial suffering, comprehension of the disease and the children’s age. Our study contributes to building a child-centered comprehensive understanding for Chinese parental HIV disclosure. It is imperative that counselors and community advocates assess and help parents achieve optimal readiness preceding disclosure of their illness to their HIV-negative children.  相似文献   
2.
Sonoelasticity imaging of prostate cancer: in vitro results   总被引:2,自引:0,他引:2  
  相似文献   
3.
Guidelines for design of clinical trials evaluating behavioral headache treatments were developed to facilitate production of quality research evaluating behavioral therapies for management of primary headache disorders. These guidelines were produced by a Workgroup of headache researchers under auspices of the American Headache Society. The guidelines are complementary to and modeled after guidelines for pharmacological trials published by the International Headache Society, but they address methodologic considerations unique to behavioral and other nonpharmacological treatments. Explicit guidelines for evaluating behavioral headache therapies are needed as the optimal methodology for behavioral (and other nonpharmacologic) trials necessarily differs from the preferred methodology for drug trials. In addition, trials comparing and integrating drug and behavioral therapies present methodological challenges not addressed by guidelines for pharmacologic research. These guidelines address patient selection, trial design for behavioral treatments and for comparisons across multiple treatment modalities (eg, behavioral vs pharmacologic), evaluation of results, and research ethics. Although developed specifically for behavioral therapies, the guidelines may apply to the design of clinical trials evaluating many forms of nonpharmacologic therapies for headache.  相似文献   
4.
Forty-one recurrent tension headache sufferers were randomly assigned to either cognitive-behavioral therapy (administered in a primarily home-based treatment protocol) or to amitriptyline therapy (with dosage individualized at 25, 50, or 75 mg/day). Cognitive-behavioral therapy and amitriptyline each yielded clinically significant improvements in headache activity, both when improvement was assessed with patient daily recordings (56% and 27% reduction in headache index, respectively), and when improvement was assessed with neurologist ratings of clinical improvement (94% and 69% of patients rated at least moderately improved, respectively). In instances where differences in treatment effectiveness were observed (headache index, somatic complaints, perceptions of control of headache activity), cognitive-behavioral therapy yielded somewhat more positive outcomes than did amitriptyline. Neither treatment, however, eliminated headache problems.  相似文献   
5.
Screening for early ovarian cancer   总被引:5,自引:0,他引:5  
Taylor  KJ; Schwartz  PE 《Radiology》1994,192(1):1
  相似文献   
6.
7.
Tumor vascular signals in renal masses: detection with Doppler US   总被引:3,自引:0,他引:3  
Ramos  IM; Taylor  KJ; Kier  R; Burns  PN; Snower  DP; Carter  D 《Radiology》1988,168(3):633-637
The vascularity of 49 renal masses (26 malignant and 23 benign lesions) was investigated with duplex Doppler ultrasound. Doppler signals obtained at the margins of renal masses were defined as "tumor signals" when the Doppler-shifted frequency of the lesion exceeded the frequency shift in the ipsilateral main renal artery. These exceeded 2.5 kHz with a 3-MHz insonating frequency. Among the 26 renal masses that subsequently proved to be malignant, tumor signals were obtained in 15 of 18 (83%) untreated renal cell carcinomas, in three of four Wilms tumors, and in two patients with metastases to the kidney, but not in the one patient with lymphoma. None of the 23 benign renal masses demonstrated tumor signals. Tumor vascularity in malignant lesions gives rise to abnormal, high-velocity, Doppler-shifted signals that can help in the differential diagnosis of renal masses.  相似文献   
8.
In human in-vitro fertilization (IVF)-embryo transfer, the in-vitro culture environment differs from in-vivo conditions in that the oxygen concentration is higher, and in such conditions the mouse embryos show a higher concentration of reactive oxygen species (ROS) in simple culture media. ROS are believed to cause damage to cell membranes and DNA fragmentation in somatic cells. This study was conducted to ascertain the level of H2O2 concentration within embryos and the morphological features of cell damage induced by H2O2. A total of 62 human oocytes and embryos (31 fragmented, 15 non-fragmented embryos, 16 unfertilized oocytes) was obtained from the IVF-embryo transfer programme. The relative intensity of H2O2 concentrations within embryos was measured using 2',7'-dichlorodihydrofluorescein diacetate by Quanti cell 500 fluorescence imaging and DNA fragmentation was observed with transmission electron microscopy and an in-situ apoptosis detection kit. The H2O2 concentrations were significantly higher in fragmented embryos (72.21 +/- 9.62, mean +/- SEM) compared to non-fragmented embryos (31.30 +/- 3.50, P < 0.05) and unfertilized oocytes (30.75 +/- 2.67, P < 0.05). Apoptosis was observed only in fragmented embryos, and was absent in non-fragmented embryos. Electron microscopic findings confirmed apoptotic bodies and cytoplasmic condensation in the fragmented blastomeres. We conclude that there is a direct relationship between increased H2O2 concentration and apoptosis, and that further studies should be undertaken to confirm these findings.   相似文献   
9.
Long-term storage of DNA is required for a number of genetic studies; prior to extraction, blood samples may be subject to elevated temperatures for variable intervals. We have studied the effect of temperatures ranging from ?70°C to +65°C on human blood and on DNA extracted from it. DNA in solution stored at ambient temperatures up to 37°C for 6 months was digestible by three different restriction endonucleases, whereas storage at 45°C is deleterious after 6-7 weeks. DNA can be extracted from blood samples stored at ?70°C for at least 2 months or at 23°C for a week or more, but blood stored at these temperatures may yield less high-molecular-weight DNA. Cell pellets from which plasma has been removed also can serve as a source of DNA. Isolated DNA stored dry for years (up to 30) is difficult to dissolve and may appear degraded, but a sample stored dry for 13 years and then in solution at ?20°C for 7 years appeared to be intact.  相似文献   
10.
The "Asthma Self-Efficacy Scale"   总被引:4,自引:0,他引:4  
According to Bandura, a person's expectations that a favorable outcome will follow a particular behavior are not sufficient to promote the occurrence of the behavior; the person must also believe that he or she will be effective at performing the behavior. The latter is referred to as self-efficacy. It has become a major focus in assessing patient performance of skills required to manage their illness. The present paper describes the development, testing, and applicability of an instrument for assessing self-efficacy in asthmatic patients. It notes that the Asthma Self-Efficacy Scale is not only a reliable paper-and-pencil instrument, but that it has a wide potential applicability throughout health care settings in measuring self-efficacy in asthmatic patients. The Asthma Self-Efficacy Scale is included.  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