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   510篇
  免费   26篇
  国内免费   19篇
儿科学   35篇
妇产科学   11篇
基础医学   52篇
口腔科学   13篇
临床医学   57篇
内科学   86篇
皮肤病学   13篇
神经病学   14篇
特种医学   113篇
外科学   79篇
综合类   11篇
预防医学   19篇
眼科学   9篇
药学   18篇
中国医学   2篇
肿瘤学   23篇
  2023年   2篇
  2021年   2篇
  2020年   6篇
  2019年   5篇
  2018年   12篇
  2017年   6篇
  2016年   7篇
  2015年   7篇
  2014年   13篇
  2013年   13篇
  2012年   9篇
  2011年   16篇
  2010年   16篇
  2009年   24篇
  2008年   15篇
  2007年   20篇
  2006年   11篇
  2005年   11篇
  2004年   9篇
  2003年   9篇
  2002年   16篇
  2001年   13篇
  2000年   4篇
  1999年   19篇
  1998年   31篇
  1997年   39篇
  1996年   31篇
  1995年   18篇
  1994年   18篇
  1993年   17篇
  1992年   3篇
  1991年   7篇
  1990年   11篇
  1989年   21篇
  1988年   12篇
  1987年   9篇
  1986年   8篇
  1985年   10篇
  1984年   4篇
  1983年   8篇
  1982年   6篇
  1981年   2篇
  1980年   11篇
  1979年   1篇
  1978年   1篇
  1977年   6篇
  1976年   7篇
  1975年   5篇
  1970年   1篇
  1968年   1篇
排序方式: 共有555条查询结果,搜索用时 0 毫秒
31.
Colorectal hemangioma: radiologic findings   总被引:1,自引:0,他引:1  
The authors correlated radiographs with the clinical and histologic data of 12 patients with colorectal hemangioma. All patients presented with rectal bleeding, which was chronic in seven. Phleboliths were also visible in seven cases, which correlated with chronic bleeding in five. On barium studies, three masses were soft and three produced rigid narrowing. The atypical features of rigid luminal narrowing, which might mimic a carcinoma, and hypovascularity correlated with chronic bleeding or visible phleboliths, which suggest the correct diagnosis of colorectal hemangioma.  相似文献   
32.
Mossalayi  MD; Mentz  F; Ouaaz  F; Dalloul  AH; Blanc  C; Debre  P; Ruscetti  FW 《Blood》1995,85(12):3594-3601
Early thymocytes undergo extensive proliferation after their entry into the thymus, but cellular interactions and cytokines regulating this intrathymic step remain to be determined. We analyzed the effects of various T-cell growth factors and cellular interactions on in vitro proliferation of early CD2+CD3/TCR-CD4-CD8- (triple negative [TN]) human thymocytes. Freshly isolated TN cells were then assayed for their growth capacity after incubation with CD2I+III-monoclonal antibody (MoAb), recombinant human interleukin-2 (IL-2), IL-7, and/or IL-4. These cells displayed significant proliferative responses with IL-4, IL- 7, or CD2-MoAb+IL-2. The addition of recombinant transforming growth factor beta (TGF beta) or autologous irradiated CD3+CD8+CD4- cells to TN cell cultures dramatically decreased their growth responses to IL-2 and IL-7, whereas IL-4-induced proliferation was less sensitive to growth inhibition. We thus asked whether the CD8+ cell-derived inhibitory effect was due to TGF beta. The addition of neutralizing anti-TGF beta MoAb completely abolished CD8+ cell-derived inhibition of TN cell growth. Analysis of CD8+ cell-derived supernatants indicated that these cells had low TGF beta 1 production capacity, whereas TN cells secrete significantly high levels of TGF beta 1. Cell fixation studies showed that TN cells were the source of the TGF beta. TGF beta 1 released from TN cells was in the latent form that became the active inhibitory form through interaction of TN cells with CD8+ cells. Together, these data suggest a role for TGF beta 1 as an externally controlled, autocrine inhibitory factor for human early thymocytes, with a regulatory role in thymic T-cell output.  相似文献   
33.
34.
35.
目的:评估静脉注射甲基强的松龙(IVMP)对外伤性视神经病变患者的疗效。方法:回顾性分析2000-01至2007-06我院收治的16例外伤性视神经病变(TON)患者的临床资料。1g甲基强的松龙分3d静脉应用,然后口服泼尼松龙11d,并逐渐减量。记录从损伤开始到治疗开始的时间。视力变化是本研究结果的主要功能评价指标。在入院时,治疗后1,2,3d;1wk和1mo时,分别记录最佳矫正视力(BCVA)。结果:共有16例患者纳入本研究,平均年龄为30岁,其中男性14例、女性2例。引起TON的主要原因有摩托车事故(占69%),打架斗殴(占19%)和体育运动(占12%)。所有患者都表现有相对传入性瞳孔障碍。在损伤后4d内开始静脉注射甲基强的松龙,采用Snellen视力表检查视力,绝大部分(56%)患者视力提高超过3行或大于等于0.5(6/12)。在损伤后5d以上才开始用类固醇治疗,视力则没有任何进步。结论:治疗TON,静脉注射中等到大剂量甲基强的松龙仍将起到重要作用。静脉注射甲基强的松龙治疗TON可能存在伤后4d的关键时期,超过了这个时期,该治疗可能就毫无效果。但还需要有更多的研究来为我们提供有明显统计学意义的数据。  相似文献   
36.
Optimization of a previously disclosed sorbitol dehydrogenase inhibitor (SDI, II) for potency and duration of action was achieved by replacing the metabolically labile N,N-dimethylsulfamoyl group with a variety of heterocycles. Specifically, this effort led to a series of novel, in vitro potent SDIs with longer serum half-lives and acceptable in vivo activity in acutely diabetic rats (e.g., 62, 67, and 69). However, the desired in vivo potency in chronically diabetic rats, ED90 less than or equal to 5 mg/kg/day, was achieved only through further modification of the piperazine linker. Several members of this family, including 86, showed better than the targeted potency with ED90 values of 1-2 mg/kg/day. Compound 86 was further profiled and found to be a selective inhibitor of sorbitol dehydrogenase, with excellent pharmacodynamic/pharmacokinetic properties, demonstrating normalization of sciatic nerve fructose in a chronically diabetic rat model for approximately 17 h, when administered orally at a single dose of 2 mg/kg/day.  相似文献   
37.

BACKGROUND:

The fecal occult blood test (FOBT), widely used as a colorectal cancer screening tool, continues to be used in hospitalized patients. However, the utility of this test for hospitalized patients is unclear.

OBJECTIVE:

To assess FOBT use in a large urban regional health authority.

METHODS:

Reports of all FOBTs performed between April 1, 2011 and March 30, 2012 from two academic and four community hospitals in Winnipeg (Manitoba) were extracted. Of 650 hospitalizations with a positive FOBT result and 1254 with a negative FOBT result, random samples of 230 and 97 charts, respectively, were reviewed. Information including demographics, admission diagnos(es), indication(s) for ordering the FOBT and clinical management was extracted.

RESULTS:

Thirty-four percent (650 of 1904) of hospitalizations with an FOBT had a positive FOBT result. Family medicine physicians ordered approximately one-half of the reviewed FOBTs. The most common indication for ordering an FOBT was anemia. Of those with a positive FOBT, 66% did not undergo further gastrointestinal investigations. Of those with a positive FOBT and overt gastrointestinal bleeding and/or melena who underwent endoscopy, 60% had their endoscopy performed before the FOBT result being reported while 38% underwent their endoscopy ≥3 days after the stool sample was collected. There were minimal differences in clinical practices between academic and community hospitals.

CONCLUSIONS:

The present study suggests that FOBT results in hospitalized patients may have little beneficial impact on clinical management. Hospital laboratories may be better served in directing resources to other tests.  相似文献   
38.
Human myeloperoxidase gene expression in acute leukemia   总被引:2,自引:0,他引:2  
Zaki  SR; Austin  GE; Swan  D; Srinivasan  A; Ragab  AH; Chan  WC 《Blood》1989,74(6):2096-2102
  相似文献   
39.
BACKGROUND: There are many advantages of breast milk for infants. Many factors can affect the volume and composition of breast milk. One of them is the maternal diet. The objective of this study is to determine the effect of Ramadan fasting on maternal nutrition and breast milk composition. METHODS: A total of 21 breast-feeding mothers aged between 17 and 38 years who fasted during Ramadan month and volunteered to give milk samples were surveyed. The ages of the infants were between 2 and 5 months. The study was performed during Ramadan and 2 weeks after the end of Ramadan. RESULTS: The results showed that during Ramadan, zinc, magnesium and potassium levels in breast milk decreased significantly (P<0.05). The mother's weight increased approximately 1 kg after Ramadan. Changes in body mass index of the mother were not statistically significant. A significant decrease in vitamin A intake was observed after Ramadan (P < 0.05). During Ramadan, energy and most nutrient intakes except protein and vitamins A and C were found below daily recommended dietary allowances necessary for lactating women. CONCLUSIONS: Ramadan fasting had no significant effect on the macronutrient composition of the breast milk and consequently the growth of the infants. There were significant differences in some of the micronutrients such as zinc, magnesium and potassium. The nutritional status of lactating women was affected by Ramadan fasting. All of the nutrient intakes (except vitamins A, E and C) decreased during Ramadan. For these reasons, it would seem prudent to excuse lactating women from fasting during Ramadan.  相似文献   
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