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   1706篇
  免费   87篇
  国内免费   6篇
耳鼻咽喉   34篇
儿科学   134篇
妇产科学   215篇
基础医学   119篇
口腔科学   25篇
临床医学   129篇
内科学   380篇
皮肤病学   28篇
神经病学   104篇
特种医学   58篇
外科学   299篇
综合类   34篇
一般理论   1篇
预防医学   39篇
眼科学   33篇
药学   88篇
中国医学   5篇
肿瘤学   74篇
  2023年   13篇
  2022年   23篇
  2021年   24篇
  2020年   19篇
  2019年   26篇
  2018年   50篇
  2017年   32篇
  2016年   49篇
  2015年   52篇
  2014年   57篇
  2013年   97篇
  2012年   118篇
  2011年   121篇
  2010年   63篇
  2009年   62篇
  2008年   124篇
  2007年   151篇
  2006年   123篇
  2005年   139篇
  2004年   116篇
  2003年   113篇
  2002年   88篇
  2001年   37篇
  2000年   26篇
  1999年   26篇
  1998年   5篇
  1997年   2篇
  1996年   1篇
  1995年   3篇
  1994年   1篇
  1993年   1篇
  1992年   7篇
  1991年   3篇
  1990年   3篇
  1989年   5篇
  1988年   6篇
  1987年   4篇
  1986年   1篇
  1985年   4篇
  1982年   1篇
  1975年   1篇
  1968年   1篇
  1966年   1篇
排序方式: 共有1799条查询结果,搜索用时 15 毫秒
51.
This study investigated the effects of 18β-glycyrrhetinic acid (GA) on neuronal damage in brain tissue caused by global cerebral ischemia/reperfusion (I/R) in C57BL/J6 mice. All subjects (n = 40) were equally divided into four groups: (1) sham-operated (SH), (2) I/R, (3) GA, and (4) GA+I/R. The SH group was used as a control. In the I/R group, the bilateral carotid arteries were clipped for 15 min, and the mice were treated with the vehicle for 10 days. In the GA group, mice were given GA (100 mg/kg) for 10 days following a median incision without carotid occlusion. In the GA+I/R group, the I/R model was applied to the mice exactly as in the I/R group, and they were then treated with the same dose of GA for 10 days. Cerebral I/R significantly induced oxidative stress via an increase in lipid peroxidaitons and a decrease in elements of the antioxidant defense systems. However, GA treatment was protective against the oxidative effects of I/R by inducing significant increases in antioxidant defense systems and a significant decrease of lipid peroxidations. Additionally, cerebral I/R increased the incidence of histopathological damage and apoptosis in brain tissue, but these neurodegenerative effects were eliminated by GA treatment. Therefore, the current study demonstrated that GA treatment effectively prevents oxidative and histological damage in the brain caused by global I/R. In this context, GA may be useful for the attenuation of the negative effects of global cerebral I/R and, in the future, it may be a viable and safe alternative treatment for ischemic stroke in humans.  相似文献   
52.
The aim of this study was to determine the effects of hesperidin (HP) on neuronal damage in brain tissue caused by global cerebral ischemia/reperfusion (I/R) in C57BL/J6 mice. For this purpose, a total of 40 mice were divided equally into four groups: (1) sham-operated (SH), (2) global cerebral I/R, (3) HP, and (4) HP+I/R. The SH group was used as a control. In the I/R group, the bilateral carotid arteries were clipped for 15 min, and the mice were treated with vehicle for 10 days. In the HP group, mice were administered HP (100 mg/kg) for 10 days without carotid occlusion. In the HP+I/R group, the I/R model was applied to the mice exactly as in the I/R group, and they were then treated with 100 mg/kg HP for 10 days. Cerebral I/R significantly induced oxidative stress via an increase in lipid peroxidation and a decrease in the components of the antioxidant defense system. Furthermore, cerebral I/R increased the incidence of histopathological damage and apoptosis in brain tissue. HP treatment significantly reversed the oxidative effects of I/R and inhibited the development of neurodegenerative histopathology. Therefore, the current study demonstrates that HP treatment effectively prevents oxidative and histological damage in the brain caused by global I/R. In this context, the beneficial effects of HP are likely a result of its strong antioxidant and free radical-scavenging properties. HP may be an useful treatment to attenuate the negative effects of global cerebral I/R.  相似文献   
53.
This study investigated whether or not the anesthetic effect of ketamine in rats is dependent on adrenal gland hormones. The study was performed on two main rat groups, intact and adrenalectomized. Rat were divided into subgroups and given appropriate doses of ketamine, metyrapone or metyrosine. Durations of anesthesia in the groups were then recorded. Endogenous catecholamine levels were measured in samples taken from peripheral blood. This experimental results showed that ketamine did not induce anesthesia in intact rats at doses of 15 or 30 mg/kg, and that at 60 mg/kg anesthesia was established for only 11 min. However, ketamine induced significant anesthesia even at a dose of 30 mg/kg in animals in which production of endogenous catecholamine (adrenalin, noradrenalin dopamine) was inhibited with metyrosine at a level of 45–47%. Ketamine at 60 mg/kg in animals in which endogenous catecholamine was inhibited at a level of 45–47% established anesthesia for 47.6 min. However, ketamine at 30 and 60 mg/kg induced longer anesthesia in adrenalectomized rats with higher noradrenalin and dopamine levels but suppressed adrenalin production. Adrenalin plays an important role in the control of duration of ketamine anesthesia, while noradrenalin, dopamine and corticosterone have no such function. If endogenous adrenalin is suppressed, ketamine can even provide sufficient anesthesia at a 2-fold lower dose. This makes it possible for ketamine to be used in lengthy surgical procedures.  相似文献   
54.
55.
56.
OBJECTIVE: To validate the Turkish translated version of the prolapse quality of life questionnaire (P-QOL). STUDY DESIGN: After establishing the test-retest reliability and internal consistency in a pilot study, 310 patients were enrolled in the study and general and subscale scores of the questionnaires were calculated. All participants underwent the International Continence Society (ICS) prolapse score (POP-Q). RESULTS: One hundred and forty-five (49.7%) women were symptomatic and 147 (50.3%) were asymptomatic. The level of missing data ranged from 0 to 2.2%. For the test-retest reliability, Spearman's rho was from 0.91 to 1.00 for all domains (p<0.001). The severity of P-QOL was strongly correlated with the vaginal examination findings among the symptomatic group (p<0.001). Items correlated with the objective vaginal examination findings. The total and domain scores for P-QOL of symptomatic and asymptomatic women were found to be statistically significant (p<0.001). CONCLUSION: The Turkish translated version of the P-QOL is reliable, consistent and valid instrument for assessing symptom severity, impact on quality of life in women with uterovaginal prolapse. It is easy to understand may be easily administered and self-completed by the women.  相似文献   
57.
BACKGROUND: This study was planned to evaluate the efficiency of the 11-14 week scan in detecting fetuses with major fetal structural abnormalities. METHODS: Some 1,290 pregnant women were submitted to a routine ultrasound scan between the 11th and 14th week after the detection of the fetal viability. The fetal anatomy was examined transabdominally, and in suspected cases transvaginally. Following the scans, the patients were examined in the second or third trimester of pregnancy. Fetal structural abnormalities classified as major and early onset were noted. Isolated choroid plexus cysts, cardiac defects not requiring treatment, mild ventriculomegaly, and mild renal pelviectasis in second trimester were not included. RESULTS: Twenty-four (1.86%) fetuses with various defects were identified, and 17 of these were diagnosed at the 11-14 week scan. The antenatal ultrasound detection rate of the fetuses with major anomalies was 95%, and 70% were detected in the first-trimester assessment. Four cardiac defects associated with genetic syndromes or requiring operation were included (0.31%) in this series. Two of the fetuses with cardiac defects (50%) had an increased nuchal translucency thickness. In this group, none of the fetuses with karyotype anomalies was born alive. CONCLUSIONS: The first-trimester scan is important in routine antenatal care for early detection of fetal defects, and determination of the fetuses at risk of cardiac anomalies and genetic syndromes.  相似文献   
58.
Self-healing is the capability of materials to repair themselves after the damage has occurred, usually through the interaction between molecules or chains. Physical and chemical processes are applied for the preparation of self-healing systems. There are different approaches for these systems, such as heterogeneous systems, shape memory effects, hydrogen bonding or covalent–bond interaction, diffusion, and flow dynamics. Self-healing mechanisms can occur in particular through heat and light exposure or through reconnection without a direct effect. The applications of these systems display an increasing trend in both the R&D and industry sectors. Moreover, self-healing systems and their energy storage applications are currently gaining great importance. This review aims to provide general information on recent developments in self-healing materials and their battery applications given the critical importance of self-healing systems for lithium-ion batteries (LIBs). In the first part of the review, an introduction about self-healing mechanisms and design strategies for self-healing materials is given. Then, selected important healing materials in the literature for the anodes of LIBs are mentioned in the second part. The results and future perspectives are stated in the conclusion section.  相似文献   
59.
Small molecule inhibitors have previously been investigated in different studies as possible therapeutics in the treatment of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). In the current drug repurposing study, we identified the leukotriene (D4) receptor antagonist montelukast as a novel agent that simultaneously targets two important drug targets of SARS-CoV-2. We initially demonstrated the dual inhibition profile of montelukast through multiscale molecular modeling studies. Next, we characterized its effect on both targets by different in vitro experiments including the enzyme (main protease) inhibition-based assay, surface plasmon resonance (SPR) spectroscopy, pseudovirus neutralization on HEK293T/hACE2+TMPRSS2, and virus neutralization assay using xCELLigence MP real-time cell analyzer. Our integrated in silico and in vitro results confirmed the dual potential effect of montelukast both on the main protease enzyme inhibition and virus entry into the host cell (spike/ACE2). The virus neutralization assay results showed that SARS-CoV-2 virus activity was delayed with montelukast for 20 h on the infected cells. The rapid use of new small molecules in the pandemic is very important today. Montelukast, whose pharmacokinetic and pharmacodynamic properties are very well characterized and has been widely used in the treatment of asthma since 1998, should urgently be completed in clinical phase studies and, if its effect is proved in clinical phase studies, it should be used against coronavirus disease 2019 (COVID-19).  相似文献   
60.
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