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   13364篇
  免费   1005篇
  国内免费   72篇
耳鼻咽喉   92篇
儿科学   394篇
妇产科学   319篇
基础医学   1964篇
口腔科学   251篇
临床医学   1310篇
内科学   3064篇
皮肤病学   283篇
神经病学   1517篇
特种医学   345篇
外科学   1328篇
综合类   107篇
现状与发展   1篇
一般理论   10篇
预防医学   1303篇
眼科学   208篇
药学   796篇
中国医学   39篇
肿瘤学   1110篇
  2024年   27篇
  2023年   222篇
  2022年   417篇
  2021年   760篇
  2020年   429篇
  2019年   616篇
  2018年   629篇
  2017年   448篇
  2016年   479篇
  2015年   471篇
  2014年   635篇
  2013年   743篇
  2012年   1125篇
  2011年   1184篇
  2010年   622篇
  2009年   516篇
  2008年   760篇
  2007年   822篇
  2006年   728篇
  2005年   681篇
  2004年   620篇
  2003年   560篇
  2002年   487篇
  2001年   49篇
  2000年   32篇
  1999年   53篇
  1998年   62篇
  1997年   54篇
  1996年   33篇
  1995年   27篇
  1994年   24篇
  1993年   16篇
  1992年   4篇
  1991年   5篇
  1990年   4篇
  1989年   6篇
  1988年   5篇
  1987年   3篇
  1986年   6篇
  1985年   4篇
  1984年   5篇
  1983年   8篇
  1981年   7篇
  1980年   6篇
  1979年   5篇
  1972年   3篇
  1967年   2篇
  1965年   2篇
  1957年   2篇
  1930年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
BACKGROUND: In contrast to aggressive mastocytosis, patients with indolent systemic mastocytosis (ISM) usually present with urticaria pigmentosa-like skin lesions. In those who lack skin lesions, mastocytosis is often overlooked or confused with endocrinologic, allergic, or other internal disorders. CASE REPORT AND RESULTS: We report on a 33-year-old male patient in whom severe hypotensive episodes occurred after contact with ants or yellow jackets. Since no specific IgE was detected, the serum tryptase concentration was measured and found to be clearly elevated (70 ng/ml). Consecutive staging and examination of the bone marrow revealed ISM. The patient was advised to circumvent insect contact, to take antihistamines on demand, and to carry an epinephrine self-injector for emergency events. In a retrospective analysis of 40 patients seen between 1988 and 2003, only 2 had a life-threatening mediator-related episode before ISM was diagnosed. CONCLUSIONS: Our report confirms the diagnostic value of tryptase in patients with suspected mastocytosis. In addition, the report suggests that the lack of typical skin lesions does not exclude an indolent form of mastocytosis even if the serum tryptase is clearly elevated. Finally, our case further shows that mastocytosis can be an important differential diagnosis to be considered in patients with unexplained anaphylactoid or other mediator-related symptoms.  相似文献   
32.
Two trials of subjects inoculated with the inactivated, gp120-depleted HIV-1 Immunogen are reported. In one study, in which 19 subjects received ZDV and 8 subjects received ddI, treatment with the HIV-1 Immunogen did not affect the pharmacokinetic parameters of the antiviral drugs. In another study, 65 subjects who were previously immunized with the HIV-1 Immunogen over a mean period of 4.0 years (range, 1.2–5.4 years) received inoculations at 0 and 6 months. At some point during this 48-week study, 72% of the subjects (47/65) were receiving antiviral drug therapy. The HIV-1 DNA load in CD4 cells and CD4 percentage were found to be stable over the 48-week period. Delayed-type hypersensitivity to HIV-1 antigens increased after two inoculations with the HIV-1 Immunogen. In these two trials, no serious treatment-related adverse events were documented in the subjects. The two studies presented herein are the first to suggest that an immune-based therapy such as the HIV-1 Immunogen can be combined safely with antiviral drugs, supporting further study to evaluate the clinical utility of this approach.  相似文献   
33.
Immune system responsiveness results from numerous factors, including endogenous cannabinoid signaling in immunocytes termed the "immunocannabinoid" system. This system can be an important signaling pathway for immune modulation. To assess the immunomodulating role of the cannabinoid 2 (CB2) receptor, we sought polymorphisms in the human gene, identified a common dinucleotide polymorphism, and investigated its effect on endocannabinoid-induced inhibition of T lymphocyte proliferation. The CB2 cDNA 188-189 GG/GG polymorphism predicts the substitution of glutamine at amino acid position 63 by arginine. T lymphocytes from CB2 188-189 GG/GG homozygotes had approximately twofold reduction of endocannabinoid-induced inhibition of proliferation compared with cells from CB2 188-189 AA/AA homozygotes. In GG/GG subjects, the reduced endocannabinoid inhibitory response was highly significant for N-arachidonylglycine and nearly significant for 2-arachidonylglycerol, and a specific CB2 receptor antagonist partially blocked these effects. Also, patients with autoimmune diseases had an increased prevalence of the homozygous GG/GG genotype. Collectively, these results demonstrate reduced endogenous fatty acid amide immunomodulatory responses in individuals with the CB2 188-189 GG/GG genotype and suggest that this CB2 gene variation may be a risk factor for autoimmunity. The results also support the proposition that the CB2 receptor may represent a novel pharmacological target for selective agonists designed to suppress autoreactive immune responses while avoiding CB1 receptor-mediated cannabinoid adverse effects.  相似文献   
34.
Gestational diabetes (GDM) is defined as any degree of glucose intolerance with onset or first recognition during pregnancy and is associated with increased feto-maternal morbidity as well as long-term complications in mothers and offspring. GDM is diagnosed by an oral glucose tolerance test (OGTT) or fasting glucose concentrations in the diabetic range. In case of a high risk for GDM/type 2 diabetes (history of GDM or prediabetes [impaired fasting glucose or impaired glucose tolerance]; malformation, stillbirth, successive abortions or birth-weight > 4500 g in previous pregnancies) performance of the OGTT (120 min; 75 g glucose) is recommended already in the first trimester and--if normal--the OGTT should be repeated in the second/third trimester. In case of clinical symptoms of diabetes (glucosuria, macrosomia) the test has to be performed immediately. All other women should undergo a diagnostic test between 24 and 28 gestational weeks. If fasting plasma glucose exceeds 95 mg/dl, 1 h 180 mg/dl and 2 hrs 155 mg/dl after glucose loading (OGTT) the woman is classified as GDM (one pathological value is sufficient). In this case a strict metabolic control is mandatory. All women should receive nutritional counseling and be instructed in blood glucose self-monitoring. If blood glucose levels cannot be maintained in the normal range (fasting < 95 mg/dl and 1 h after meals < 130 mg/dl) insulin therapy should be initiated. Maternal and fetal monitoring is required in order to minimize maternal and fetal/neonatal morbidity and perinatal mortality. After delivery all women with GDM have to be reevaluated as to their glucose tolerance by a 75 g OGTT (WHO criteria).  相似文献   
35.
T lymphocytes encounter hypoxia when they migrate to pathological sites such as tumours and wounds. The inability of T cells to provide an efficient defence at these sites can in part be explained by the hypoxic environment. Kv1.3 channels, important components of the T cell activation process are inhibited by hypoxia and their inhibition accounts for a hypoxia-induced decrease in T cell proliferation. Although Kv1.3 channels play a key role in T cell O2 sensing, the signalling mechanisms mediating their response to hypoxia are still not understood. In this study, we show that the src-protein tyrosine kinase p56Lck (Lck) is required for Kv1.3 channel response to hypoxia. Pre-exposure to the src inhibitor PP2 abolished the hypoxia-induced inhibition of Kv1.3 channels in primary human T lymphocytes. Moreover, Kv1.3 channel sensitivity to hypoxia was lost in Lck-deficient Jurkat T cells. Further studies with recombinant Kv1.3 channels showed that Kv1.3 channels lack intrinsic O2 sensitivity, but delivery of Lck into the cells and transfection of a constitutively active Lck (Y505FLck) restored their sensitivity to hypoxia. Although Lck is necessary for the Kv1.3 channel response to hypoxia, it does not directly inhibit Kv1.3 channels. Indeed, under normal oxygen tension, delivery of active Lck into L929 cells and overexpression of Y505FLck did not decrease recombinant Kv1.3 currents. On the contrary, activation of endogenous src kinases increased wild-type Kv1.3 currents in T lymphocytes. Our findings indicate that Lck is required for the acute response to hypoxia of human T lymphocytes as it is necessary to confer O2 sensitivity on Kv1.3 channels.  相似文献   
36.
In addition to their robust difference in trait anxiety, as illustrated by a variety of behavioral tests, HAB and LAB rats differ in their stress coping strategies, the former being more susceptible and vulnerable to stressor exposure and preferring more passive strategies. HAB rats of either gender show signs of a hyper-reactive hypothalamic-pituitary-adrenocortical (HPA) axis, thus resembling psychiatric patients. As shown by in situ hybridization and microdialysis in freely behaving animals, both the expression and release of vasopressin in the hypothalamic paraventricular nucleus are higher in HAB than in LAB rats, thus contributing to the HPA axis hyperdrive. Accordingly, in HAB animals, administration of a V1 receptor antagonist normalized the pathological outcome of the dexamethasone/corticotropin-releasing hormone test and triggered behavioral changes toward reduced anxiety and active stress coping. Pharmacological validation has revealed signs of depressive-like behavior, as HAB but not LAB rats have shown more active stress coping behavior and a normalized HPA axis after treatment with paroxetine. Of interest, this antidepressant reduced the hypothalamic overexpression of vasopressin; this novel mechanism of action is likely to contribute to paroxetine effects on both behavioral and neuroendocrine parameters. Cross-mating and cross-fostering paradigms showed that the divergent emotionality in HAB vs. LAB rats is determined genetically, rather than postnatally through maternal behavior. As the behavioral and neuroendocrine phenotyping pointed to the vasopressin gene as a candidate gene critically involved in anxiety, preliminary genetic approaches have been focused on this gene, revealing single nucleotide polymorphisms (SNPs) in the promotor area of the vasopressin gene in HAB, but not LAB rats. HAB/LAB rats are thus proving to be a unique animal model to identify and characterize neurobiological, neuroendocrine, and genetic correlates of trait anxiety, and perhaps depression, in humans.  相似文献   
37.
Hand injuries at leisure   总被引:1,自引:0,他引:1  
In a survey of 383 moderate and severe hand injuries in adults, 246 (64.4%) occurred outwith work. Falling (sixty-four patients) and punching (forty-eight patients) were the commonest mechanisms of blunt injury. Glass (eight), knives (seven) and "do-it-yourself" materials (eight) were most frequently implicated in sharp trauma. No outstandingly dangerous hobbies or social activities were identified.  相似文献   
38.
Prevention Science - Screening is an essential prevention practice for a number of health conditions. However, screening coverage remains generally low. Studies that investigate determinants of...  相似文献   
39.
Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz - Partizipation zu ermöglichen ist Teil des Auftrags der Offenen Kinder- und Jugendarbeit. Dazu gehört die Einbindung der...  相似文献   
40.
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