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   13938篇
  免费   656篇
  国内免费   118篇
耳鼻咽喉   95篇
儿科学   272篇
妇产科学   408篇
基础医学   1721篇
口腔科学   354篇
临床医学   957篇
内科学   3949篇
皮肤病学   217篇
神经病学   1311篇
特种医学   582篇
外科学   2098篇
综合类   34篇
一般理论   1篇
预防医学   499篇
眼科学   155篇
药学   694篇
中国医学   23篇
肿瘤学   1342篇
  2024年   12篇
  2023年   89篇
  2022年   201篇
  2021年   409篇
  2020年   207篇
  2019年   299篇
  2018年   390篇
  2017年   289篇
  2016年   323篇
  2015年   362篇
  2014年   551篇
  2013年   698篇
  2012年   970篇
  2011年   988篇
  2010年   641篇
  2009年   581篇
  2008年   997篇
  2007年   998篇
  2006年   905篇
  2005年   951篇
  2004年   849篇
  2003年   780篇
  2002年   697篇
  2001年   81篇
  2000年   68篇
  1999年   98篇
  1998年   147篇
  1997年   108篇
  1996年   128篇
  1995年   85篇
  1994年   98篇
  1993年   79篇
  1992年   66篇
  1991年   54篇
  1990年   49篇
  1989年   40篇
  1988年   31篇
  1987年   20篇
  1986年   34篇
  1985年   31篇
  1984年   30篇
  1983年   23篇
  1982年   32篇
  1981年   33篇
  1980年   31篇
  1979年   20篇
  1976年   10篇
  1975年   8篇
  1974年   8篇
  1964年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
OBJECTIVE: The purpose of this study is to investigate the safety and effectiveness of a short-scheme protocol of gemeprost for second trimester induction of abortion in women with previous uterine surgery. STUDY DESIGN: Retrospective review of women who underwent second trimester medical termination of pregnancy (TOP) at our hospital in a 5-year period. A short regimen of gemeprost was used: over a 24-h period, 1 mg vaginal gemeprost was given every 3 h up to three doses after which, if abortion did not occur, another course at the same dosage schedule was administered up to 4 days. Induction failure was defined as women undelivered by 96 h. A homogeneous population was identified. Statistical analysis was performed with the chi(2) test or Fisher's Exact Test for categorical data and t test for continuous variables. RESULTS: Four hundred seventeen women underwent medical midtrimester TOP in the 5-year study period. Two hundred five patients were selected for this review, comparing 63 patients with scarred uterus to 142 women without uterine scars. There were no differences between the two groups in induction-to-abortion interval and number of pessaries given. The overall failure of induction rate was 1.5% and need for blood transfusion was 0.5%. No uterine rupture was reported. CONCLUSION: The regimen of gemeprost proposed seems to be as safe and effective in patients with uterine scars as in women with unscarred uteri with a very low incidence of complications.  相似文献   
992.
993.
We conducted a serologic survey among dogs and cats in Italy to detect antibodies against severe acute respiratory syndrome virus 2 (SARS-CoV-2). We found that SARS-CoV-2 seroprevalence was higher among cats (16.2%) than dogs (2.3%). In addition, seroprevalence was higher among animals living in close contact with SARS-CoV-2–positive owners.  相似文献   
994.
Neuronal loss and irreversible brain damage often cause the worsening of symptoms and the decreased efficacy of pharmacological treatment occurring in epileptic patients and animal models of kindling. Recently we reported that the neurotransmitter/neuromodulatory peptide Cholecystokinin-8 (CCK-8) is able to induce the structural and functional neuronal recovery of chemical- and surgical-induced lesions when i.p. injected in rodents. The present study therefore, was aimed at verifying the hypothesis that treatment with a CCK-8 dose having a neuroprotective action might affect brain alterations and the development of kindling in adult rats receiving the convulsant agent pentylenetetrazole (PTZ). Compared to rats receiving Saline prior to PTZ, which manifested clonic-tonic seizures (Class 5 behavioural change scale) after three weeks of treatment, rats pre-treated with CCK-8 showed an improvement of behavioural score exhibiting myoclonus and occasionally tonic seizures (Class 3/4). This decreased susceptibility to develop convulsions was associated with the recovery of PTZ-induced reduction of ChAT levels in forebrain and GABA/GAD expression in the hippocampus. Furthermore, NPY immunoreactivity distribution and NPY mRNA levels were also increased in the hippocampus of rats receiving CCK-8 injection before each PTZ treatment. These data indicate that CCK-8 possesses the ability to prevent and/or suppress the convulsant effects of PTZ by stimulating the synthesis of neurotransmitters/peptides involved in the inhibition of hippocampal hyper-excitability. Our findings suggest that CCK-8 may have anticonvulsant and neuroprotective properties that merit further investigation.  相似文献   
995.
The impact of a rehabilitative multi-step dietary program consisting in different diets has been scantily investigated. In an open-label study, 73 obese patients underwent a two-phase weight loss (WL) program: a 3-week protein-sparing, very low-calorie, ketogenic diet (<500?kcal/day; Oloproteic® Diet) and a 6-week hypocaloric (25–30?kcal/kg of ideal body weight/day), low glycemic index, Mediterranean-like diet (hypo-MD). Both phases improved visceral adiposity, liver enzymes, GH levels, blood pressure and glucose and lipid metabolism. However, the hypo-MD was responsible for a re-increase in blood lipids and glucose tolerance parameters. Changes in visceral adiposity and glucose control-related variables were more consistent in patients with metabolic syndrome. However, in these patients the hypo-MD did not result in a consistent re-increase in glucose control-related variables. A dietary program consisting in a ketogenic regimen followed by a balanced MD appeared to be feasible and efficacious in reducing cardiovascular risk, particularly in patients with metabolic syndrome.  相似文献   
996.
The primary aim of the present study was to compare the effects of agomelatine (AGO) and venlafaxine XR (VLX) on anhedonia in patients with major depressive disorder. Secondary end points were to test its antidepressant and anxiolytic efficacy.Sixty patients were enrolled and randomly assigned to two different treatments: AGO (25-50 mg/d; n = 30 subjects) or VLX (75-150 mg/d, n = 30 subjects). Psychopathological assessment was performed at baseline and after 8 weeks of treatment with the Snaith Hamilton Rating Scale (SHAPS), the Hamilton Depression Rating Scale, the Hamilton Anxiety Rating Scale, and the Clinical Global Impression for anhedonia, depression, anxiety, and global improvement, respectively.Both groups showed a significant reduction in time for the SHAPS, the Hamilton Depression Rating Scale, and the Hamilton Anxiety Rating Scale. A significant between-group difference was observed for SHAPS scores: patients treated with AGO showed a more relevant reduction compared with that in VLX-treated patients. Moreover, only patients treated with AGO showed a statistically significant improvement in Clinical Global Impression scores.In this study, AGO showed significantly greater efficacy on anhedonia and similar antidepressant efficacy to the serotonin-norepinephrine reuptake inhibitor VLX in patients with major depressive disorder during an 8-week treatment period. Anhedonia has been considered a potential trait marker related to vulnerability for depression. Therefore, the efficacy of AGO on this dimension holds particular importance in the treatment of patients with anhedonic features.  相似文献   
997.
Insulin-loaded solid lipid nanoparticles (SLN), obtained by the solvent-in-water emulsion–diffusion technique, were produced using isovaleric acid (IVA) as organic phase, glyceryl mono-stearate (GMS) as lipid, soy lecithin and sodium taurodeoxycholate (TDC) as emulsifiers. IVA, a partially water-miscible solvent with low toxicity, was used to dissolve both insulin and lipids. SLN of spherical shape were obtained by simple water dilution of the O/W emulsion. Analysis of SLN content after processing showed interesting encapsulation efficiency with respect to therapeutic doses; moreover, insulin did not undergo any chemical modification within the nanoparticles and most of it remained stable after incubation of the SLN with trypsin solution. The biological activity of insulin, i.e. the ability to decrease glycemia in rats, was not negatively influenced by the SLN production process, as after subcutaneous administration of insulin extracted from SLN to animals, the blood glucose levels were quite similar to those obtained after administration of a conventional insulin suspension. Consequently, SLN seem to have interesting possibilities as delivery systems for oral administration of insulin.  相似文献   
998.
In this paper a device, based on urease-loaded microspheres, is presented. The first task of this work was the optimization of a procedure for the alginate microspheres realization, having a radius as close as possible to the optimal one necessary to achieve the maximum enzyme exploitation. This optimal radius was calculated theoretically through a mathematical model which describes the concentration of substrate (urea) inside the microspheres on the assumption of a diffusion-reaction mechanism. The enzyme-loaded microspheres were successfully tested in a prototypal device aimed at the depletion of urea from a circulating fluid simulating blood flow: the results showed that urea concentration in the circulating fluid drops down to less than 25% of the initial value after 5 h.  相似文献   
999.
Abstract

This article describes three cases o f Datura stramonium intake o n two nonconsecutive days. In the first case, the patient took a small amount of D. stramonium seeds without showing any symptoms of intoxication. The other two patients had taken a considerable amount of seeds and reported a sudden surge in strength and energy, with some aggressive compulsion towards their peers. They showed delirium as well as confusion and disorientation. The absence of any specific legislation makes D. stramonium a tempting alternative to other psychoactive substances. Thus, it is extremely important to be able to recognize its symptoms so as to be able to diagnose any signs of intoxication properly.  相似文献   
1000.
Acetyl-L-carnitine (ALC) is a naturally occurring molecule with an important role in cellular bioenergetics and as donor of acetyl groups to proteins, including NF-κB p65. In humans, exogenously administered ALC has been shown to be effective in mood disturbances, with a good tolerability profile. No current information is available on the antidepressant effect of ALC in animal models of depression and on the putative mechanism involved in such effect. Here we report that ALC is a proneurogenic molecule, whose effect on neuronal differentiation of adult hippocampal neural progenitors is independent of its neuroprotective activity. The in vitro proneurogenic effects of ALC appear to be mediated by activation of the NF-κB pathway, and in particular by p65 acetylation, and subsequent NF-κB-mediated upregulation of metabotropic glutamate receptor 2 (mGlu2) expression. When tested in vivo, chronic ALC treatment could revert depressive-like behavior caused by unpredictable chronic mild stress, a rodent model of depression with high face validity and predictivity, and its behavioral effect correlated with upregulated expression of mGlu2 receptor in hippocampi of stressed mice. Moreover, chronic, but not acute or subchronic, drug treatment significantly increased adult born neurons in hippocampi of stressed and unstressed mice. We now propose that this mechanism could be potentially involved in the antidepressant effect of ALC in humans. These results are potentially relevant from a clinical perspective, as for its high tolerability profile ALC may be ideally employed in patient subpopulations who are sensitive to the side effects associated with classical antidepressants.  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