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   32408篇
  免费   2357篇
  国内免费   141篇
耳鼻咽喉   369篇
儿科学   817篇
妇产科学   437篇
基础医学   4199篇
口腔科学   650篇
临床医学   2949篇
内科学   6797篇
皮肤病学   468篇
神经病学   3650篇
特种医学   1487篇
外国民族医学   3篇
外科学   4726篇
综合类   685篇
一般理论   66篇
预防医学   2812篇
眼科学   620篇
药学   2005篇
中国医学   21篇
肿瘤学   2145篇
  2023年   113篇
  2022年   190篇
  2021年   448篇
  2020年   258篇
  2019年   446篇
  2018年   575篇
  2017年   424篇
  2016年   489篇
  2015年   583篇
  2014年   878篇
  2013年   1395篇
  2012年   2052篇
  2011年   2179篇
  2010年   1175篇
  2009年   1123篇
  2008年   2069篇
  2007年   2229篇
  2006年   2171篇
  2005年   2372篇
  2004年   2095篇
  2003年   1925篇
  2002年   1953篇
  2001年   348篇
  2000年   284篇
  1999年   352篇
  1998年   442篇
  1997年   425篇
  1996年   386篇
  1995年   383篇
  1994年   307篇
  1993年   290篇
  1992年   252篇
  1991年   270篇
  1990年   252篇
  1989年   233篇
  1988年   201篇
  1987年   221篇
  1986年   184篇
  1985年   197篇
  1984年   244篇
  1983年   235篇
  1982年   287篇
  1981年   280篇
  1980年   235篇
  1979年   139篇
  1978年   151篇
  1977年   100篇
  1976年   130篇
  1975年   90篇
  1974年   109篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Abstract: We have analyzed the plasma pharmacokinetics of busulfan in 272 patients receiving high-dose oral busulfan and intravenous cyclophosphamide in conjunction with allogeneic or autologous bone marrow transplantation. The patients ranged in age from 2 months to 59 yr (mean 10, median 12 yr) and had the following diagnoses: thalassemia or sickle cell anemia (n = 74); leukemia or myelodysplasia (n = 112); inborn errors of metabolism (n = 41) or immunodeficiency (n = 45). Plasma specimens were collected following the first dose for each patient which ranged from 1 to 4 mg/kg (mean ± SD, 1.21 ± 0.41, median 1.15). Busulfan was quantitated using ultraviolet absorbance detection after derivatization and HPLC separation. Pharmacokinetic parameters were derived by modeling the raw data to fit first-order single compartment kinetics. The kinetic parameters showed wide interpatient variability independent of age and diagnosis. There was a statistically significant correlation of age with the following parameters: area under the curve (AUC); maximal concentration; minimum concentration; clearance; volume of distribution and absorption half-time. The coefficients of determination (i.e. correlation coefficient squared) were low ranging from 0.04 to 0.12 implying only a small part (i.e. 4–12%) of the variance was explained by age. Although busulfan pharmacokinetics are age-related most of the variability is not explained by age or diagnosis.  相似文献   
92.
93.
94.
To address a recurring shortage of nurses in the aboriginal communities of Northwestern Ontario, the First Nations and Inuit Health Branch, Health Canada, commissioned a study to explore the viability of establishing a relief pool among nurses from nearby small industrial towns. An open/close-ended survey completed by a random sample of 237 nurses from the target population documented levels of awareness, willingness, and preparedness for northern practice, as well as recruitment incentives and disincentives. Findings demonstrate an awareness of the overlap between the professional and personal dimensions characteristic of such practices, and suggest support for innovative rotations that would cut across federal/provincial/community jurisdictions. Although complex, given time and willingness, a regional relief system seems viable.  相似文献   
95.
OBJECTIVE: To characterize dementia-induced changes in visual art production. BACKGROUND: Although case studies show altered visual artistic production in some patients with neurodegenerative disease, no case-controlled studies have quantified this phenomenon across groups of patients. METHOD: Forty-nine subjects [18 Alzheimer disease, 9 frontotemporal dementia (FTD), 9 semantic dementia (SD), 15 healthy older controls (NC)] underwent formal neuropsychologic testing of visuospatial, perceptual, and creative functioning, and produced 4 drawings. Subjective elements of drawings were rated by an expert panel that was blind to diagnosis. RESULTS: Despite equal performance on standard visuospatial tests, dementia groups produced distinct patterns of artistic features that were significantly different from NCs. FTDs used more disordered composition and less active mark-making (P<0.05). Both FTDs and SDs drawings were rated as more bizarre and demonstrated more facial distortion than NCs (P<0.05). Also, SDs drastically failed a standardized test of divergent creativity. Alzheimer disease artwork was more similar to controls than to FTDs or SDs, but showed a more muted color palette (P<0.05) and trends toward including fewer details, less ordered compositions, and occasional facial distortion. CONCLUSIONS: These group differences in artistic style likely resulted from disease-specific focal neurodegeneration, and elucidate the contributions of particular brain regions to the production of visual art.  相似文献   
96.
97.
98.
Summary It was previously shown that 11 months after ovariectomy the volume fraction of trabecular bone in the spine and 11th rib medullary canal of Beagle dogs (6 control, 9 ovariectomized) was significantly reduced. In this paper it is shown that these changes are accompanied by increased marrow fat volume in the 11th rib (59.0±9.5% vs. 44.3 ±10.0%). Conversely, the volume fraction of functional (hematopoietic) cells in the marrow was reduced by ovariectomy. Additionally, variations in marrow fat volume were tested for correlation with 22 other variables pertinent to bone physiology. Marrow fat volume was significantly positively correlated with serum osteocalcin, rib trabecular bone porosity, rib cross-sectional area, and gains in body weight. It was negatively correlated with serum estrogen concentrations and the extent of rib trabecular surfaces labeled with tetracycline.  相似文献   
99.
In 1980 a syndrome was first described in two adult males, consisting of macrocephaly, pigmented macules on the glans and shaft of the penis, and hamartomatous intestinal polyps. Since then, 10 additional cases have been identified. Herein, we present two new cases and review the cutaneous manifestations as well as additional features in patients with the Ruvalcaba-Myhre-Smith syndrome.  相似文献   
100.
Access to and utilization of care for HIV-positive Asians (A) and Pacific Islanders (PI) have been largely unaddressed despite the rising influx of immigrants from Asia and the Pacific to the United States and the growing HIV prevalence in these regions. This paper describes the cultural attitudes, behaviors, and perceptions that affect access to and utilization of care among Asian undocumented noncitizens living with HIV/AIDS (UNWHA) in New York City. Sixteen semistructured interviews with HIV-positive UNWHAs revealed that their access to care was influenced by community misperceptions of HIV transmission, discriminatory attitudes towards persons living with HIV, competing immigration related stressors, and difficulty navigating service systems. These findings underscore the importance of integrating HIV treatment with primary prevention and awareness of immigration-related stressors to ensure timely access to screening services and care among Asian UNWHAs.  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