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   891篇
  免费   54篇
耳鼻咽喉   6篇
儿科学   56篇
妇产科学   92篇
基础医学   117篇
口腔科学   15篇
临床医学   136篇
内科学   123篇
皮肤病学   8篇
神经病学   47篇
特种医学   16篇
外科学   117篇
综合类   8篇
预防医学   81篇
眼科学   5篇
药学   76篇
中国医学   1篇
肿瘤学   41篇
  2021年   9篇
  2020年   9篇
  2018年   9篇
  2016年   8篇
  2015年   13篇
  2014年   22篇
  2013年   23篇
  2012年   38篇
  2011年   41篇
  2010年   21篇
  2009年   22篇
  2008年   38篇
  2007年   47篇
  2006年   27篇
  2005年   23篇
  2004年   28篇
  2003年   26篇
  2002年   23篇
  2001年   22篇
  2000年   17篇
  1999年   20篇
  1998年   6篇
  1997年   6篇
  1995年   12篇
  1994年   7篇
  1992年   23篇
  1991年   17篇
  1990年   18篇
  1989年   32篇
  1988年   23篇
  1987年   24篇
  1986年   32篇
  1985年   25篇
  1984年   22篇
  1983年   18篇
  1982年   10篇
  1981年   7篇
  1979年   15篇
  1978年   13篇
  1976年   10篇
  1975年   13篇
  1974年   10篇
  1973年   10篇
  1972年   15篇
  1971年   13篇
  1970年   9篇
  1969年   10篇
  1968年   9篇
  1967年   6篇
  1966年   6篇
排序方式: 共有945条查询结果,搜索用时 31 毫秒
1.
Many hospitals today have implemented widely disparate information systems on mainframe and mini-computer hardware. The advent of network technology in hospitals has made it possible to access information in these systems. Unfortunately, the user interfaces to applications on these systems are unique and difficult to learn, which makes them unsuitable for use by clinical services. In this paper we describe the development of a Physician's Workstation which integrates information from multiple existing information systems and discuss how the workstation makes it possible to move from the departmental systems of the present to the computer-based medical record system of the future.  相似文献   
2.
The limitations of current methods of measuring bilirubin are well established and relate to the broad dynamic range and inability of the technique to determine different but structurally similar bilirubin species. New instrumentation and methodology circumvent these limitations, and clinical studies are beginning to reveal their increased diagnostic usefulness. Nevertheless, in several clinical situations, for example, the prediction of kernicterus, better bilirubin determinations may not eliminate the controversy surrounding appropriate therapeutic interventions.  相似文献   
3.
4.
Mannich bases were synthesized and converted to the corresponding arylhydrazones. X-ray analysis of a ketone (1a) and a hydrazone (4d) revealed structural features of interest. All of the compounds showed cytotoxicity toward murine lymphocytic leukemia L1210 cells in the 4.9-25.0-microM range. The correlation coefficients generated by plotting the IC50 values (the concentrations of compounds that inhibit the growth of tumors by 50%) of some hydrazones against certain electronic, hydrophobic, and steric constants of the aryl substituents indicated only weak correlations. A few ketones and hydrazones displayed significant cytotoxicity to the WiDr human colon cancer cells, and these derivatives, especially the ketones, may serve as prototypes for future drug development. The KB tumor (a human epidermoid carcinoma of the nasopharynx) was somewhat refractory to selected compounds. In an in vitro assay conducted by the National Cancer Institute and involving approximately 53 tumor cell lines originating from eight neoplastic diseases, 65% of the compounds showed some selectivity toward one or more groups of cancers, principally leukemia, melanoma, and colon cancer. The bioevaluation of the ketones and hydrazones against the L1210, WiDr, and KB tumors, as well as evidence from proton nuclear magnetic resonance studies did not support the suggestion that hydrazones may be prodrugs of the corresponding ketones.  相似文献   
5.
Aneurysm wrapping is an uncommon procedure used only when clipping or ligature is not feasible. This article contains a brief discussion of the various modalities of aneurysm wrapping in its early years, product options available today, characteristics and manifestations of intracranial aneurysms and a synopsis of the surgical procedure. In addition, perioperative nursing care is discussed.  相似文献   
6.
OBJECTIVE: This study used population-based data bases to assess the association of trauma centers with per capita county hospitalization and trauma death rates in the State of North Carolina. SUMMARY BACKGROUND DATA: The current study extended previous work using two North Carolina data bases to assess the association of the presence of a trauma center with per capita county trauma death rates. METHODS: Data on per capita county trauma hospitalizations and deaths were obtained from the state hospital discharge data base and the North Carolina Medical Examiner's data base. Bivariate and multivariate analysis techniques were used. The dependent variables of interest were prehospital, hospital, and total trauma death rates and hospitalization rates for injury. RESULTS: Bivariate analysis identified a number of factors associated with per capita county hospitalizations and trauma death rates. These included the per cent unemployment, racial distribution, county alcohol tax receipts, and advanced life support certified emergency medical services providers. The per capita trauma death rates were significantly lower in counties with trauma centers compared with those without trauma centers (4.0 +/- 0.5 and 5.0 +/- 1.1 deaths per 10,000 population, p = 0.0001, respectively). The per capita hospitalizations for trauma were also lower in counties with trauma centers. Multivariate modeling showed that the presence of a trauma center and advanced life support providers were the best predictors of decreased per capita county trauma death rates. CONCLUSIONS: The study showed that the presence of a trauma center and advanced life support training were the two medical system factors that were the best predictors of the per capita county prehospital and total trauma death rates. These findings are consistent with the hypothesis that trauma centers are associated with a decrease in trauma death rates.  相似文献   
7.
Fifteen apparent errors of observation, reporting, interpretation, or attribution occurring in the insect repellent and attractant literature were examined. Topics discussed are the boiling point effect, solvents and solutions, repellent-treated netting, terpineol and diphenyl oxide, lactic acid, the smell and feel of deet (diethylmethylbenzamide), effective half-life, protection time, protection time of deet for men and women, McGuire's formula, "plussing out", King's classification, exorbitant doses, extrapolated doses, and extreme observations. The decay constant (1.36 hr-1) and half-life (0.51 hr) of a mosquito-repellent bath oil (Skin-So-Soft) are reported for the first time.  相似文献   
8.
Papillary cystadenoma of the epididymis is an uncommon benign lesion that may occur sporadically or as a manifestation of von Hippel—Lindau (VHL) disease. Neither immunohistochemical studies nor molecular genetic analyses of the VHL gene have been reported previously for this lesion. The authors describe two cases of clear cell papillary cystadenoma of the epididymis, both of which were initially confused with metastatic renal cell carcinoma. Both lesions showed positive immunohistochemical staining for low and intermediate molecular weight keratins (Cam 5.2 and AE1/AE3), EMA, vimentin, α1-antitrypsin, and α1-antichymotrypsin. Each was negative for CEA. Because clear cell papillary cystadenoma is similar to renal cell carcinoma histologically, and because both occur as components of the von Hippel—Lindau disease complex, the authors analyzed both cases for the presence of mutations in the VHL gene. A somatic VHL gene mutation was detected in one of the two tumors by polymerase chain reaction followed by single-strand conformation polymorphism analysis. Direct sequencing revealed a cytosine to thymine transition at nucleotide 694, resulting in the replacement of an arginine with a stop codon after the sixth amino acid of exon 3. As the VHL gene is believed to function as a tumor suppressor gene, VHL gene mutations may play a role in the initiation of tumorigenesis in sporadic cystadenomas of the epididymis.  相似文献   
9.
This work describes our experience in reviewing the performance criteria for display systems and how we have implemented a practical approach to the assessment of the workstation environment in a large tertiary care hospital. The acceptance criteria contained in the draft report of Topic Group 18 of the American Association of Physicists in Medicine (AAPM) were used as a basis for assessment of primary and secondary displays. A telescopic photometer was used to measure the maximum luminance and the contrast ratio of the image for the displays used in our radiology department and in the operating and emergency rooms using the standard Society of Motion Picture and Television Engineers (SMPTE) pattern, in ambient light and with light decreased as much as possible. About half of the displays met the AAPM criteria for minimum luminance and contrast ratio in low light. None of the systems met the contrast ratio criteria in ambient light. The challenges in improving the performance and calibrating displays are discussed.  相似文献   
10.
We describe the first documented field transmission of West Nile (WN) virus by a North American mosquito. WN was first detected in northern Florida in 2001. An intensive mosquito trapping and surveillance program was conducted in this region for four nights to assess mosquito transmission of WN. Four mosquito traps, each with a single sentinel chicken, were placed at five different locations on each of four nights. A total of 11,948 mosquitoes was collected, and 14 mosquito pools were found to contain WN, giving a minimum infection rate between 1.08 and 7.54 per 1,000. Only one of the 80 sentinel chickens seroconverted to WN, demonstrating a single mosquito transmission event during the study and a mosquito transmission rate of between 0.8 and 1 per 1,000. Culex nigripalpus Theobald was responsible for WN transmission to the sentinel chicken, although both Cx. nigripalpus and Culex quinquefasciatus Say were found infected with WN. Mosquito transmission rates are reported in this study for the first time for a WN outbreak. This information is essential to determine risk of human and animal infection.  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