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   1966篇
  免费   93篇
  国内免费   12篇
耳鼻咽喉   65篇
儿科学   32篇
妇产科学   26篇
基础医学   452篇
口腔科学   70篇
临床医学   131篇
内科学   496篇
皮肤病学   22篇
神经病学   223篇
特种医学   25篇
外科学   180篇
综合类   3篇
一般理论   1篇
预防医学   98篇
眼科学   3篇
药学   135篇
中国医学   10篇
肿瘤学   99篇
  2023年   3篇
  2022年   17篇
  2021年   23篇
  2020年   11篇
  2019年   29篇
  2018年   43篇
  2017年   22篇
  2016年   22篇
  2015年   37篇
  2014年   39篇
  2013年   82篇
  2012年   100篇
  2011年   116篇
  2010年   65篇
  2009年   76篇
  2008年   129篇
  2007年   152篇
  2006年   144篇
  2005年   165篇
  2004年   138篇
  2003年   124篇
  2002年   143篇
  2001年   30篇
  2000年   32篇
  1999年   29篇
  1998年   36篇
  1997年   20篇
  1996年   17篇
  1995年   13篇
  1994年   12篇
  1993年   10篇
  1992年   17篇
  1991年   20篇
  1990年   19篇
  1989年   13篇
  1988年   16篇
  1987年   16篇
  1986年   8篇
  1985年   8篇
  1984年   11篇
  1983年   4篇
  1982年   5篇
  1981年   7篇
  1980年   5篇
  1979年   11篇
  1978年   7篇
  1977年   7篇
  1976年   4篇
  1974年   5篇
  1973年   3篇
排序方式: 共有2071条查询结果,搜索用时 0 毫秒
81.
In contrast to the noradrenergic dysregulation described in PTSD, little is known regarding noradrenergic function in dissociative disorders. The purpose of this preliminary study was to investigate basal norepinephrine in depersonalization disorder (DPD). Nine subjects with DSM-IV DPD, without lifetime PTSD, were compared to nine healthy comparison (HC) subjects. Norepinephrine was measured via 24-h urine collection and three serial plasma determinations. Groups did not differ significantly in plasma norepinephrine levels. Compared to the HC group, the DPD group demonstrated significantly higher urinary norepinephrine, only prior to covarying for anxiety. The DPD group also demonstrated a highly significant inverse correlation between urinary norepinephrine and depersonalization severity (r=-0.88). Norepinephrine and cortisol levels (reported in a prior study) were not intercorrelated. We concluded that although dissociation accompanied by anxiety was associated with heightened noradrenergic tone, there was a marked basal norepinephrine decline with increasing severity of dissociation. The findings are in concordance with the few reports on autonomic blunting in dissociation and merit further investigation.  相似文献   
82.
Hypothalamic pituitary adrenal axis abnormalities have been described in posttraumatic stress disorder (PTSD), and among the recently traumatized. Plasma cortisol and continuous measures of PTSD symptoms were obtained from 21 survivors, at 1 week and 6 months after traumatic events. Eight survivors met Clinician Administered PTSD Scale criteria for PTSD at 6 months. Cortisol levels at 1 week did not predict subsequent PTSD. Survivors with and without PTSD had similar mean levels of cortisol at both time points. Cortisol levels at 6 months negatively correlated with self-reported PTSD symptoms within PTSD subjects.  相似文献   
83.
The distal femur is a common site for primary and metastatic bone tumors and therefore, it is a frequent site in which limb-sparing surgery is done. Between 1980 and 1998, the authors treated 110 consecutive patients who had distal femur resection and endoprosthetic reconstruction. There were 61 males and 49 females who ranged in age from 10 to 80 years. Diagnoses included 99 malignant tumors of bone, nine benign-aggressive lesions, and two nonneoplastic conditions that had caused massive bone loss and articular surface destruction. Reconstruction was done with 73 modular prostheses, 27 custom-made prostheses, and 10 expandable prostheses. Twenty-six gastrocnemius flaps were used for soft tissue reconstruction. All patients were followed up for a minimum of 2 years. Function was estimated to be good or excellent in 94 patients (85.4%), moderate in nine patients (8.2%), and poor in seven patients (6.4%). Complications included six deep wound infections (5.4%), six aseptic loosenings (5.4%), six prosthetic polyethylene component failures (5.4%), and local recurrence in five of 93 patients (5.4%) who had a primary bone sarcoma. The limb salvage rate was 96%. Distal femur endoprosthetic reconstruction is a safe and reliable technique of functional limb sparing that provides good function and local tumor control in most patients.  相似文献   
84.
There is no system for reporting drug and alcohol-related emergency department (ED) visits in Israel. This pilot survey was aimed at examining the feasibility of establishing an ED surveillance system in a general hospital and a psychiatric hospital. We describe the design and preliminary results of a pilot-survey conducted in the emergency departments of two hospitals in Northern Israel. Active and passive case identification was conducted in Rambam Hospital and Tirat Carmel Psychiatric Hospital, from August, 1999-January, 2000. A total of 160 ED patients were identified, 64% as drug-related, with heroin being the most common drug. The majority of cases were identified through self-reports. Overdose and IVDU complications accounted for 20% of drug cases identified at Rambam Hospital, and injury and motor vehicle accidents accounted for 12% of all visits at this hospital. We did not attempt to estimate the proportion of all ED visits that are associated with drugs and/or alcohol. Under-ascertainment of cases and incomplete data recording remain major concerns for a survey of this nature. Results of this pilot survey indicate that with proper training of ED nurses a national ED surveillance system can be successfully and efficiently established in general hospitals and psychiatric hospitals in Israel.  相似文献   
85.
Glutamate is an essential neurotransmitter in the CNS. However, at abnormally high concentrations it becomes cytotoxic. Recent studies in our laboratory showed that glutamate evokes T cell-mediated protective mechanisms. The aim of the present study was to examine the nature of the glutamate receptors and signalling pathways that participate in immune protection against glutamate toxicity. We show, using the mouse visual system, that glutamate-induced toxicity is strain dependent, not only with respect to the amount of neuronal loss it causes, but also in the pathways it activates. In strains that are genetically endowed with the ability to manifest a T cell-dependent neuroprotective response to glutamate insult, neuronal losses due to glutamate toxicity were relatively small, and treatment with NMDA-receptor antagonist worsened the outcome of exposure to glutamate. In contrast, in mice devoid of T cell-dependent endogenous protection, NMDA receptor antagonist reduced the glutamate-induced neuronal loss. In all strains, blockage of the AMPA/KA receptor was beneficial. Pharmacological (with alpha2-adrenoceptor agonist) or molecular intervention (using either mice overexpressing Bcl-2, or DAP-kinase knockout mice) protected retinal ganglion cells from glutamate toxicity but not from the toxicity of NMDA. The results suggest that glutamate-induced neuronal toxicity involves multiple glutamate receptors, the types and relative contributions of which, vary among strains. We suggest that a multifactorial protection, based on an immune mechanism independent of the specific pathway through which glutamate exerts its toxicity, is likely to be a safer, more comprehensive, and hence more effective strategy for neuroprotection. It might suggest that, because of individual differences, the pharmacological use of NMDA-antagonist for neuroprotective purposes might have an adverse effect, even if the affinity is low.  相似文献   
86.
Intravenous gamma globulin (IVIg) is produced from a pool of precipitated IgG from over 3,000 healthy donors. IVIg was originally given to subjects with Igs deficiencies. Later on its beneficial effects on a diverse autoimmune clinical conditions were revealed. Based on large experimental studies in mice as well as limited clinical experience, we consider IVIg useful in preventing metastatic spread. In mice, the employment of IVIg reduced significantly metastatic spread of melanoma, carcinoma and sarcoma. The effect of IVIg was achieved following i.v. or s.c. administration at high dose (2 g/kg body weight) and at 100 times lower doses. The effect of IVIg on the prevention of metastases are diverse and achieved via enhancement of IL-12 secretion and increased NK activity as well as inhibition of matrix metalloproteinase-9 (MMP-9). The lack of serious side effects with the remarkable decrease in metastatic spread make IVIg a suitable adjuvant therapy in early and advanced cancer conditions.  相似文献   
87.
BACKGROUND: Postoperative pain is mediated centrally by N-methyl-D-aspartate (NMDA) receptors. The beneficial effects of preincision oral dextromethorphan (DM), which is an NMDA antagonist, on postoperative pain and intravenous patient-controlled analgesia (IV-PCA) morphine (MO) consumption have been examined in patients undergoing surgery. The authors investigated 75 patients who underwent surgery for bone and soft tissue malignancies, in whom postoperative pain is more severe compared with patients who undergo general surgery. METHODS: Patients received placebo, DM 60 mg, or DM 90 mg (25 patients per group) before surgery and on each of the two following days in a randomized, double-blind, placebo-controlled manner. Postoperative IV-PCA MO was started when subjective pain intensity was >/= 4/10 (visual score) and lasted for 72 hours. Rescue drugs on demand were oral paracetamol or dipyrone. RESULTS: The patients in the DM60 and DM90 groups similarly experienced 50-80% less pain (P < 0.01) compared with patients in the placebo group, both immediately and up to 3 days postoperatively, as well as a 50% reduction in the estimated overall maximal pain intensity (P < 0.01). Both DM groups consumed 50-70% less MO than the nonmedicated individuals in the placebo group (P < 0.01), and their demand for rescue drugs on the first postoperative day also was significantly lower (P < 0.01). Patients in the DM groups also were sedated less ( approximately 70%; P < 0.01). There were no differences among the groups in terms of when the patients left their beds, when they were discharged home, or the number of overall side effects. CONCLUSIONS: DM is associated with reduced pain intensity, sedation, and analgesic requirements, even in patients undergoing surgery for bone and soft tissue malignancies. A 3-day DM administration neither increased the incidence of side effects nor accelerated ambulation and discharge home.  相似文献   
88.
Shapiro S  Shoenfeld Y  Gilburd B  Sobel E  Lahat N 《Cancer》2002,95(9):2032-2037
BACKGROUND: Degradation of the extracellular matrix (ECM) is essential for progression and metastasis of cancer cells. The ECM-degrading enzymes, matrix metalloproteinases (MMPs), are produced mainly by intratumor monocytes/macrophages. MMPs, particularly MMP-9, are reported to be of crucial significance for both growth and tumor invasiveness. Inhibition of the expression of MMP-9 may prevent tumor development. High-dose intravenous gamma globulins (IVIG) effectively inhibit metastatic spread of tumors in mice and humans and a variety of mechanisms have been suggested to explain this effect. METHODS: We studied the effect of purified IVIG on MMP-9 secretion and mRNA expression by in vitro differentiated human monocytic cells (cell lines and peripheral blood monocytes). Zymography was employed to measure gelatinase secretion and Northern blot analysis was used to detect mRNA expression. Involvement of F(ab)(2) and Fc components in IVIG activity was also evaluated. RESULTS: IVIG dose dependently and significantly reduced the amount of secreted MMP-9 and its mRNA expression. F(ab)(2), but not Fc fragments, led to suppressed MMP-9 activity. However, competitive experiments demonstrated that Fc, but not F(ab)(2) fragments, reversed the IVIG-induced inhibitory effects. CONCLUSIONS: These results suggest that the whole IgG molecule may be needed for pertinent IVIG-induced MMP-9 down-regulation. This study points to an additional new mechanism whereby IVIG may play a beneficial role in the prevention of tumor spread in humans.  相似文献   
89.
90.
In the following review we will discuss some familiar drugs with potential use as adjuvant anti-neoplastic agents. We will highlight their unfamiliar property of being able to inhibit matrix metalloproteinase-9 activity, which has recently been proven to play a key role in cancer spread. These drugs' high-safety profile may allow clinicians to construct new anti-cancer protocols that may prove to be less toxic alternatives to those commonly used.  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