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   1611篇
  免费   82篇
  国内免费   4篇
耳鼻咽喉   18篇
儿科学   50篇
妇产科学   43篇
基础医学   239篇
口腔科学   12篇
临床医学   268篇
内科学   324篇
皮肤病学   22篇
神经病学   110篇
特种医学   38篇
外科学   130篇
综合类   19篇
一般理论   7篇
预防医学   171篇
眼科学   8篇
药学   108篇
  1篇
肿瘤学   129篇
  2024年   2篇
  2023年   6篇
  2022年   25篇
  2021年   48篇
  2020年   22篇
  2019年   38篇
  2018年   47篇
  2017年   37篇
  2016年   42篇
  2015年   34篇
  2014年   48篇
  2013年   79篇
  2012年   138篇
  2011年   116篇
  2010年   76篇
  2009年   69篇
  2008年   114篇
  2007年   137篇
  2006年   129篇
  2005年   128篇
  2004年   88篇
  2003年   86篇
  2002年   70篇
  2001年   10篇
  2000年   7篇
  1999年   7篇
  1998年   16篇
  1997年   8篇
  1996年   9篇
  1995年   14篇
  1994年   12篇
  1993年   4篇
  1992年   2篇
  1991年   5篇
  1990年   2篇
  1989年   4篇
  1988年   2篇
  1987年   1篇
  1986年   3篇
  1985年   2篇
  1984年   1篇
  1979年   1篇
  1969年   1篇
  1968年   5篇
  1965年   1篇
  1926年   1篇
排序方式: 共有1697条查询结果,搜索用时 15 毫秒
991.
OBJECTIVE: Oxidative stress is linked to an increased incidence of cardiovascular disease in men. The objective of this research was to delineate whether daily consumption of orange pulp (OP) modifies antioxidant status and decreases cardiovascular risk factors in orchidectomized rats. METHODS: In the present study, 45 1-y-old male rats were randomized to a sham-control group (n = 9) and an orchidectomized group (n = 36). The orchidectomized group was equally divided among the following five treatments: orchidectomy (ORX), ORX + 2.5% OP, ORX + 5% OP, and ORX + 10% OP. One hundred twenty days after the study began, all rats were sacrificed and plasma was harvested for its antioxidant status, C-reactive protein (CRP), lipid profile, and indices of peroxidation. Superoxide dismutase (SOD) and catalase activities in the liver were also monitored. RESULTS: Orchidectomy decreased (P < 0.05) plasma levels of antioxidant, SOD, catalase, and CRP and increased (P < 0.05) plasma levels of malondialdehyde, nitrite, and lipid profile compared with the sham-control group. In contrast to ORX, ORX + OP increased (P < 0.05) plasma antioxidant, dose-dependently increased (P < 0.05) SOD and catalase, decreased (P < 0.05) plasma malondialdehyde, nitrite, cholesterol, and triacylglycerol concentrations in the liver; and had no effect (P > 0.1) on plasma CRP or lipid profiles. CONCLUSION: The beneficial effect of eating an orange is demonstrated by the increasing antioxidant status and by the decreasing peroxidation independent of plasma triacylglycerol, cholesterol, or CRP concentrations.  相似文献   
992.
Oxidative stress and hypogonadism are linked to the increased incidence of cardiovascular disease in males. The objective of this research was to delineate whether drinking cranberry juice for 4 months affects antioxidant capacity and lipid profile in orchidectomized rats. Thirty-two 1-year-old male rats were randomized to two groups: a sham-control group (n = 8) and an orchidectomized group (n = 24). The orchidectomized group was divided into three groups of eight and assigned to one of the following treatments: orchidectomy, orchidectomy plus 27% cranberry juice, and orchidectomy plus 45% cranberry juice. At 120 days after initiation of the study, all rats were killed, blood was collected, and plasma was harvested for total antioxidant status, malondialdehyde, nitrate + nitrite, and superoxide dismutase (SOD) activity in liver, and concentrations of cholesterol and triglyceride in liver and in plasma. Orchidectomy depressed (P < .05) plasma antioxidant capacity and SOD activity, elevated (P < .05) nitrate + nitrite and malondialdehyde in plasma, and increased (P < .05) triglyceride and cholesterol values in liver and in plasma. Cranberry juice increased (P < .05) plasma antioxidant capacity and SOD activity and reduced (P < .05) nitrate + nitrite and malondialdehyde concentrations. Drinking cranberry juice did not affect cholesterol concentrations in liver and in plasma. Triglyceride concentration in plasma of orchidectomized rats that were drinking cranberry juice increased (P < .05), but its concentration in liver decreased (P < .05) to the level of shams. The protective effect of cranberry juice from oxidative damage may be mediated by a decrease in nitrate + nitrite and dose-dependent decrease in peroxidation.  相似文献   
993.
Canadian Journal of Anesthesia/Journal canadien d'anesthésie - In the context of a programmed intermittent epidural bolus (PIEB) regimen for labour analgesia, one can identify an upper...  相似文献   
994.
995.
OBJECTIVE: This pilot study assessed the opinions of medical students, residents, and attending physicians regarding the technical standards for medical school admission and the competencies required of graduates in the context of physical disability issues. DESIGN: Students, residents, and faculty from all specialties at a major academic medical center were surveyed regarding the concept of the "undifferentiated graduate;" the relative importance of motor, sensory, observation, and communication skills; the importance of specific technical skills; and the use of physician extenders and other accommodations to fulfill technical standards. RESULTS: Respondents placed higher importance on observation and communication skills compared with motor skills. Of respondents, 69.8% either disagree or strongly disagree with the idea that a medical student should be an undifferentiated candidate possessing all the technical skills necessary to enter any specialty. CONCLUSIONS: Technical skills used in interpretation and observation were more important to respondents than those technical skills that are purely procedural. Respondents largely rejected the concept of the undifferentiated graduate. Although statistical analyses are of limited reliability because of low response rates, this study represents the most extensive sampling to date of medical professionals' opinions on these issues. Respondents' narrative comments also provided valuable perspectives.  相似文献   
996.
Although multiple adenosine receptors have been identified, the subtype and underlying mechanisms involved in the relaxation response to adenosine in the urinary bladder remain unclear. The present study investigates changes in the membrane potential, as assessed by fluorescence-based techniques, of bladder smooth muscle cells by adenosine receptor agonists acting via ATP-sensitive potassium (K(ATP)) channels. Membrane hyperpolarization evoked by adenosine and various adenosine receptor subtype-selective agonists was attenuated or reversed by the K(ATP) channel blocker glyburide. Comparison of adenosine receptor agonist potencies eliciting membrane potential effects showed a rank order of potency 5'-N-ethyl-carboxamido adenosine (NECA; -log EC50 = 7.97) approximately 2-p-(2-carboxethyl)phenethyl-amino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS-21680; 7.65) > 2-chloro adenosine (5.90) approximately 2-chloro-N6-cyclopentyladenosine (CCPA; 5.51) approximately N6-cyclopentyladenosine approximately N6-(R)-phenylisopropyladenosine > 2-chloro- N6-(3-iodobenzyl)-adenosine-5'-N-methyl-carboxamide (2Cl-IBMECA; 4.78). Membrane potential responses were mimicked by forskolin, a known activator of adenylate cyclase, and papaverine, a phosphodiesterase inhibitor. The A(2A)-selective antagonist 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-yl-amino] ethyl)phenol (ZM-241385), and the adenylate cyclase inhibitor N-(cis-2-phenyl-cyclopentyl) azacyclotridecan-2-imine-hydrochloride (MDL-12330A) inhibited the observed change in membrane potential evoked by adenosine and adenosine-receptor agonists. The rank order potency for relaxation of K+-stimulated guinea pig bladder strips, NECA (-log EC50 = 6.41) approximately CGS-21680 (6.38) > 2-chloro adenosine (5.90) > CCPA approximately 2Cl-IBMECA (>4.0) was comparable to that obtained from membrane potential measurements. Collectively, these studies demonstrate that adenosine-evoked membrane hyperpolarization and relaxation of bladder smooth muscle is mediated by A(2A) receptor-mediated activation of K(ATP) channels via adenylate cyclase and elevation of cAMP.  相似文献   
997.
998.
999.
Nursing facilities must be committed to ongoing leadership development and to developing and retaining their staff in the increasingly competitive healthcare market. In this article, the authors share the processes involved in creating a focused small group approach to developing clinical leaders. Programmatic approaches to development, clarity of needs of those targeted for development, individual development plans, external expertise partnerships, and small group session dynamics are discussed. Applications of the process and lessons learned from the program will benefit others in their efforts to enhance organization succession planning, leadership development, group learning, and program administration.  相似文献   
1000.
This article describes the evaluation of learning as an integral and critical component of educational program evaluation and one determinant of effectiveness. Various concept, models, processes, and research findings offer practical options for conducting learning and program evaluation. The article discusses how predetermined goals or outcomes guide organizational processes to determine effectiveness. The article further reinforces the importance of valid and reliable data collection used to conduct evaluation processes, then subsequently determine the worth, effectiveness, and success or failure of learning and program outcomes. Key evaluation and effectiveness elements and their relationships are shown.  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