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   441篇
  免费   24篇
  国内免费   7篇
耳鼻咽喉   2篇
儿科学   6篇
妇产科学   6篇
基础医学   72篇
口腔科学   3篇
临床医学   51篇
内科学   89篇
皮肤病学   6篇
神经病学   62篇
特种医学   10篇
外科学   47篇
综合类   7篇
预防医学   13篇
眼科学   5篇
药学   50篇
中国医学   5篇
肿瘤学   38篇
  2023年   2篇
  2022年   6篇
  2021年   5篇
  2020年   3篇
  2019年   7篇
  2018年   7篇
  2017年   6篇
  2016年   8篇
  2015年   7篇
  2014年   14篇
  2013年   16篇
  2012年   31篇
  2011年   32篇
  2010年   10篇
  2009年   17篇
  2008年   28篇
  2007年   27篇
  2006年   30篇
  2005年   34篇
  2004年   33篇
  2003年   18篇
  2002年   21篇
  2001年   6篇
  2000年   9篇
  1999年   4篇
  1998年   4篇
  1996年   3篇
  1993年   2篇
  1991年   4篇
  1990年   4篇
  1989年   4篇
  1986年   2篇
  1979年   2篇
  1978年   1篇
  1977年   3篇
  1976年   1篇
  1975年   2篇
  1974年   4篇
  1973年   2篇
  1972年   11篇
  1971年   5篇
  1970年   4篇
  1969年   7篇
  1968年   4篇
  1967年   3篇
  1966年   1篇
  1965年   4篇
  1964年   1篇
  1963年   1篇
  1961年   2篇
排序方式: 共有472条查询结果,搜索用时 15 毫秒
81.
BACKGROUND: Separate reports from the maintenance treatment for late-life depression (MTLD) trials have shown that low socioeconomic status (SES) and anxiety symptoms at the time of treatment initiation predict lower levels of response to antidepressant treatment and higher levels of suicidal ideation in older adults. AIM: To determine whether SES and anxiety independently contribute to worse treatment outcomes, as indicated by persistence of depressive symptoms during treatment and the persistence of suicidal ideation. Consistent with prior evidence that sociodemographic factors and clinical history are both prognostic of depression treatment efficacy, we hypothesized that SES and pre-existing anxiety symptoms will both predict lower levels of response to treatment and higher levels of suicidal ideation. METHOD: Secondary analyses of data from the MTLD trials. RESULTS: Regression analyses which controlled for comorbid anxiety indicated that residents of middle- and high-income census tracts were more likely to respond to treatment (HR, 1.63; 95%CI, 1.08-2.46) and less likely to report suicidal ideation during treatment (OR, 0.51; 95%CI, 0.28-0.90) than residents of low income census tracts. The same regression models indicated that pre-existing anxiety symptoms were independently related to lower treatment response (HR, 0.73; 95%CI, 0.60-0.89) and higher risk of suicidal ideation (OR, 1.45; 95%CI, 0.98-2.14). CONCLUSION: These findings demonstrate the importance of treating anxiety symptoms during the course of treatment for late-life depression and, at the same time, addressing barriers to treatment response related to low SES.  相似文献   
82.
BackgroundThe aura symptoms in migraine are most likely due to cortical spreading depression (CSD). CSD is favored by NMDA receptor activation and increased cortical excitability. The latter probably explains why migraine with aura may appear when estrogen levels are high, like during pregnancy. Kynurenic acid, a derivative of tryptophan metabolism, is an endogenous NMDA receptor antagonist whose cerebral concentrations can be augmented by systemic administration of its precursor l-kynurenine.ObjectiveTo determine if exogenous administration of l-kynurenine is able to influence KCl-induced CSD in rat, if the effect is sex-dependent and if it differs in females between the phases of the estrous cycle.MethodsAdult Sprague–Dawley rats (n = 8/group) received intraperitoneal (i.p.) injections of l-kynurenine (L-KYN, 300 mg/kg), L-KYN combined with probenecid (L-KYN + PROB) that increases cortical concentration of KYNA by blocking its excretion from the central nervous system, probenecid alone (PROB, 200 mg/kg) or NaCl. Cortical kynurenic acid concentrations were determined by HPLC (n = 7). Thirty minutes after the injections, CSDs were elicited by application of 1 M KCl over the occipital cortex and recorded by DC electrocorticogram. In NaCl and L-KYN groups, supplementary females were added and CSD frequency was analyzed respective to the phases of the estrous cycle determined by vaginal smears.ResultsIn both sexes, PROB, L-KYN and L-KYN + PROB increased cortical kynurenic acid level. PROB, L-KYN and L-KYN + PROB with increasing potency decreased CSD frequency in female rats, while in males such an effect was significant only for L-KYN + PROB. The inhibitory effect of L-KYN on CSD frequency in females was most potent in diestrus.Conclusionl-Kynurenine administration suppresses CSD, most likely by increasing kynurenic acid levels in the cortex. Females are more sensitive to this suppressive effect of l-kynurenine than males. These results emphasize the role of sex hormones in migraine and open interesting novel perspectives for its preventive treatment.  相似文献   
83.
BACKGROUND AND PURPOSE: Cerebellar atrophy is considered the most prominent neuroradiologic finding in Marinesco-Sj?gren syndrome (MSS). Our purpose was to investigate this neuroradiologic feature in a series of patients with MSS. METHODS: Five patients with MSS (age range, 5-19 years) underwent native MR imaging of the brain. The findings were assessed with particular attention to the cerebellum and the supratentorial structures. RESULTS: Only two patients had slight cerebellar atrophy; the cerebellum was normal in size and configuration in the other patients. Additional supratentorial findings were present in some of the patients, with an apparently small anterior pituitary gland in two and the absence of the posterior pituitary bright spot in three of the patients. CONCLUSION: Cerebellar atrophy is not an obligatory finding in MSS, and almost normal cranial MR imaging results are compatible with the diagnosis. Morphologic changes of the pituitary gland seem to be common in patients with MSS and are not associated with endocrine dysfunction.  相似文献   
84.
OBJECTIVE: Deficits in executive functions may play an important role in late-life suicide; however the association is understudied. This study examined cognitive function in general and executive functioning specifically in depressed elderly with and without suicidal ideation and attempts. DESIGN: Case-control study. Setting: University-affiliated psychiatric hospital. PARTICIPANTS: We compared 32 suicidal depressed participants aged 60 and older with 32 non-suicidal depressed participants equated for age, education, and gender. MEASUREMENTS: We assessed global cognitive function and executive function with the Dementia Rating Scale (DRS) and the Executive Interview (EXIT25), respectively. RESULTS: Suicidal and non-suicidal depressed groups were comparable in terms of severity of depression and burden of physical illness. Suicidal participants performed worse on the EXIT25, and on the DRS total scale, as well as on Memory and Attention subscales. The differences were not explained by the presence of dementia, substance use, medication exposure, or brain injury from suicide attempts. CONCLUSIONS: Poor performance on tests of executive function, attention, and memory is associated with suicidal behavior in late-life depression.  相似文献   
85.
Myocardial ischaemia and reperfusion lead to myocardial cell death due, at least in part, to apoptotic mechanisms. Although cysteinyl aspartate-specific proteinase (caspase) activation is a major event and the most-cited culprit in the development of apoptosis, its potential contribution to ischaemic myocardial cell death is largely unknown. To study the role of caspase activation, isolated rat hearts (n=6 per group) were subjected to 30 min coronary artery occlusion followed by 120 min reperfusion. A non-selective [0.1 or 0.5 microM acetyl-Tyr-Val-Ala-Asp chloromethylketone (YVAD-cmk)] or selective caspase inhibitors [0.07 or 0.2 microM acetyl-Asp-Glu-Val-Asp-cmk (Ac-DEVD-cmk, caspase-3 inhibitor); 0.07 or 0.2 microM benzoxycarbonyl-Leu-Glu-OMe-His-Asp(OMe)-fluoromethylketone (z-LEHD-fmk, caspase-9 inhibitor)] were added to the perfusate at the start of reperfusion. Non-selective caspase inhibition with 0.1 or 0.5 microM YVAD-cmk limited infarct size: (21 +/- 4%, P<0.05; 17 +/- 3%, P<0.05, respectively) compared with the ischaemic/reperfused control (32 +/- 5%). In hearts treated with 0.1 or 0.5 microM caspase II non-selective inhibitor, the fraction of terminal-deoxynucleotidyl-transferase deoxyuridine nick end labelling (TUNEL)-positive myocyte nuclei in the infarcted zone was reduced from the ischaemic/reperfused non-treated control of 11.2 +/- 2.1% to 6.2 +/- 1.6% (P<0.05) and 1.2 +/- 0.2% (P<0.05), respectively. The recovery of post-ischaemic cardiac function (coronary flow, aortic flow and left-ventricular developed pressure) improved significantly with the application of the non-selective caspase inhibitor as well. In hearts perfused with specific caspase inhibitors (caspase-3 and caspase-9) there was no significant reduction in the infarct size, no improvement in post-ischaemic cardiac function and no reduction of apoptotic cell death. We conclude that non-specific inhibition of caspases may be therapeutically beneficial in myocardial ischaemia/reperfusion-induced damage, while selective caspase inhibitors may fail to prevent such reperfusion-induced injury in our model system.  相似文献   
86.
87.
Summary We have recently reported the specific binding of [3H]resiniferatoxin to sensory ganglion membranes; this binding appears to represent the postulated vanilloid (capsaicin) receptor. In the present report, we compare the structure/activity relations for binding to rat dorsal root ganglion membranes and for biological responses in the rat, using a series of vanilloids of the capsaicin (homovanilloyl-decylamide, homovanilloyl-dodecylamide, homovanilloyl-cyclododecylamide, homovanilloyl-hexadecylamide, homovanilloyl-piperidine and nonenoyl-homoveratrylamide) and resiniferatoxin (tinyatoxin, 12-deoxyphorbol 13-phenylacetate 20-homovanillate) classes. We find that all the tested biologically active vanilloids, but not the inactive structure analogs, compete for the [3H]resiniferatoxin binding sites in rat dorsal root ganglion membranes, and we conclude that the [3H]resiniferatoxin binding assay may provide an efficient approach for evaluating such compounds. We also provide evidence that the [3H]resiniferatoxin receptor is likely to recognize vanilloids which are inserted into the membranes; and that the apparent activity of capsaicinoids may be significantly influenced by factors other than equilibrium binding affinities. Send offprint requests to P. M. Blumberg at the above address  相似文献   
88.
The clinical use of TRPV1 (transient receptor potential vanilloid subfamily, member 1; also known as VR1) antagonists is based on the concept that endogenous agonists acting on TRPV1 might provide a major contribution to certain pain conditions. Indeed, a number of small-molecule TRPV1 antagonists are already undergoing Phase I/II clinical trials for the indications of chronic inflammatory pain and migraine. Moreover, animal models suggest a therapeutic value for TRPV1 antagonists in the treatment of other types of pain, including pain from cancer. We argue that TRPV1 antagonists alone or in conjunction with other analgesics will improve the quality of life of people with migraine, chronic intractable pain secondary to cancer, AIDS or diabetes. Moreover, emerging data indicate that TRPV1 antagonists could also be useful in treating disorders other than pain, such as urinary urge incontinence, chronic cough and irritable bowel syndrome. The lack of effective drugs for treating many of these conditions highlights the need for further investigation into the therapeutic potential of TRPV1 antagonists.  相似文献   
89.
In the present study, hepatoprotective effect of Cassia fistula fruit extract was investigated in mice. Animals were divided into six groups receiving normal saline (1), bromobenzene (460 mg/kg) alone (2) and together with increasing doses (200, 400, 600, 800 mg/kg) of a crude hydro-alcoholic extract of Cassia fistula fruit (3-6, respectively). All administrations were carried out orally, daily, for 10 days. On the 11th day, animals were sacrificed. Serum activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and gamma glutamyl transpeptidase (γGT) were determined; serum levels of direct and total bilirubin were measured; furthermore, livers were prepared for histological examination. Our results showed that bromobenzene treatment alone elicited a significant increase in activities of AST, ALT, ALP (but not γGT), and it significantly elevated the levels of direct and total bilirubin. Co-treatment with Cassia fistula fruit extract, however, significantly and dose-dependently decreased the above-mentioned enzyme activities (with exception of γGT) and bilirubin levels, producing a recovery to the naive state. The protective effect of Cassia fistula fruit extract against liver injury evoked by bromobenzene was confirmed by histological examination as well. In conclusion, the Cassia fistula fruit extract has significant hepatoprotective effect in our murine model.  相似文献   
90.
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