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   108487篇
  免费   6151篇
  国内免费   697篇
耳鼻咽喉   1052篇
儿科学   3524篇
妇产科学   2466篇
基础医学   15628篇
口腔科学   3938篇
临床医学   9892篇
内科学   24357篇
皮肤病学   2725篇
神经病学   10612篇
特种医学   2522篇
外国民族医学   1篇
外科学   9662篇
综合类   526篇
一般理论   48篇
预防医学   10789篇
眼科学   1751篇
药学   7639篇
中国医学   436篇
肿瘤学   7767篇
  2024年   123篇
  2023年   1037篇
  2022年   2244篇
  2021年   3697篇
  2020年   2317篇
  2019年   3114篇
  2018年   3523篇
  2017年   2699篇
  2016年   3139篇
  2015年   3479篇
  2014年   4560篇
  2013年   5945篇
  2012年   9033篇
  2011年   9411篇
  2010年   5131篇
  2009年   4319篇
  2008年   7461篇
  2007年   7459篇
  2006年   6868篇
  2005年   6404篇
  2004年   5773篇
  2003年   5162篇
  2002年   4647篇
  2001年   595篇
  2000年   404篇
  1999年   607篇
  1998年   807篇
  1997年   664篇
  1996年   555篇
  1995年   460篇
  1994年   431篇
  1993年   358篇
  1992年   301篇
  1991年   201篇
  1990年   206篇
  1989年   189篇
  1988年   179篇
  1987年   149篇
  1986年   159篇
  1985年   116篇
  1984年   139篇
  1983年   137篇
  1982年   157篇
  1981年   119篇
  1980年   129篇
  1979年   79篇
  1978年   77篇
  1977年   70篇
  1976年   58篇
  1974年   53篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
The anatomic response to intravitreal bevacizumab injection in three patients with aggressive, posterior retinopathy of prematurity is described. In all cases, the worse eye was treated with a single intravitreal injection of 0.75 mg of bevacizumab as monotherapy or complementary to laser therapy. In 24 hours, all injected eyes showed regression of the tunica vasculosa lentis and iris vessel engorgement and disappearance of iris rigidity. In addition, plus disease and retinal proliferation began to regress. None of the eyes required additional treatment. Follow-up of up to 10 months  相似文献   
62.
Prevalence of isolated left ventricular (LV) diastolic dysfunction has been reported to be as high as one-third of all heart failure (HF) cases, with an increasing prevalence in the elderly population. However, there is a paucity of prospective data about the prevalence and prognosis of isolated LV diastolic dysfunction in an unselected population of patients hospitalized with HF. Therefore, we prospectively evaluated 179 consecutive patients discharged from our hospital with HF to assess the prevalence of systolic versus diastolic LV dysfunction among patients hospitalized with HF and to compare their demographics, clinical features, self-perceived quality of life (QOL), and 6-month readmission rate and mortality. Among them, 133 (59% men, median age 74 years) showed in sinus rhythm and had no significant primary valvular disease. LV diastolic dysfunction was diagnosed on the basis of the European Study Group on Diastolic HF echocardiographic criteria. QOL was assessed at hospital discharge and 6-month follow-up visit using the Minnesota Living with HF questionnaire. Survival of patients with HF was compared with that of age- and sex-matched general population. In all, 29 patients (22%) had isolated LV diastolic dysfunction and 102 (78%) had prevalent LV systolic dysfunction (ie, LV ejection fraction 相似文献   
63.
Atopy may be associated with a reduced T-cell function early in life, particularly regarding maturation of Th1 responses. The T-cell surface molecules CD2 and CD28 are involved in important T-cell activation pathways. Stimulation via the CD2 receptor increases the responsiveness to interleukin (IL)-12, which is a potent inducer of Th1 responses, whereas CD28 stimulation is critical for Th2 differentiation. Our aim was to prospectively study the expression of the cell-surface markers CD2 and CD28 on T-cells in relation to development of atopic disease. Children (n = 172) were followed from birth to 18 months and the cumulative history of atopic disease was recorded. Blood samples were obtained at birth and at 18 months, and in a subgroup of 78 infants also at 3, 6 and 12 months. Flow cytometry was used to analyze the T-cell markers CD2 and CD28, the latter also within the subsets of T-helper (CD4+) and T-cytotoxic (CD8+) cells. At 18 months, 31 children had and 118 did not have atopic symptoms. At this age, skin prick test (SPT) positive children with atopic symptoms with or without an atopic family history (AFH) showed a lower expression of CD2 mode fluorescence intensity (FI) as well as a lower proportion of CD2+ cells, as compared with non-sensitized children with neither atopic symptoms nor AFH. This was accompanied by a higher expression of CD28 FI on CD2+CD8+CD28+ cells. No significant differences were seen at time points before 18 months, although the proportion of CD2+ tended to be low also earlier in life. In conclusion, the observed reduced expression of CD2 in atopic infants may support previous findings that atopy is associated with a reduced CD2 function. The high CD28 FI in SPT positive children with atopic symptoms may possibly be a consequence of a TH2-skewed immune system.  相似文献   
64.
The purpose of this study was to present normative values for thumb abduction and adduction and also to present measures of reliability of the measuring system arising from the use of the Ab-Adductometer. With the Ab-Adductometer, we obtained abductor and adductor measurements of intrinsic muscle strength of the healthy hand thumb in 600 volunteers. Handgrip strength values were obtained with the Jamar dynamometer. Age and male-female specific reference ranges for the Ab-Adductometer and the Jamar dynamometer are presented. This study, with a very large number of volunteer subjects, 600, presents reference ranges for pure palmar adduction and abduction of the thumb. The results indicate that the Ab-Adductometer is a clinically useful device for the purpose of quantitatively measuring thumb adduction and abduction strength at various starting angles of thumb abduction relative to the plane of the palm. The device may be especially helpful in the evaluation of compressive neuropathies of the median or ulnar nerves such as carpal tunnel syndrome or cubital tunnel syndrome as well as for primary disease of the peripheral nerves that affect intrinsic muscles and for thumb function in proximal conditions such as tetraplegia and brachial plexopathy.  相似文献   
65.
Apical ballooning is a novel clinical entity reported in different contexts of physical and psychological stress, which is more common in middle-aged women. Of unknown etiology, the syndrome is characterized by a sudden and transient dilatation of the left ventricular apex in the absence of obstructive atherosclerotic coronary disease or evidence of myocardial necrosis, with total late recovery of ventricular function. The authors report the case of a 53-year-old woman who was admitted to the emergency room with left arm ischemia and low cardiac output, requiring ventilatory support. Left catheterization showed typical medial and apical myocardial dysfunction, with normal coronary arteries. Transesophageal echocardiography revealed a thrombus attached to the lower face of the aortic arch, which probably explained the thromboembolism of the arm but was unlikely to be the cause of the left ventricular dysfunction since there were no enzymatic or electrocardiographic signs of myocardial necrosis and normal wall motion was fully recovered.  相似文献   
66.
67.
68.
69.
BACKGROUND/PURPOSE: The polysaccharide-rich composition of Aloe vera extracts (Aloe barbadensis Miller), often used in cosmetic formulations, may impart moisturizing properties to the product. The aim of this study was to evaluate the effect of cosmetic formulations containing different concentrations of freeze-dried Aloe vera extract on skin hydration, after a single and a 1- and 2-week period of application, by using skin bioengineering techniques. METHODS: Stable formulations containing 5% (w/w) of a trilaureth-4 phosphate-based blend were supplemented with 0.10%, 0.25% or 0.50% (w/w) of freeze-dried Aloe vera extract and applied to the volar forearm of 20 female subjects. Skin conditions in terms of the water content of the stratum corneum and of transepidermal water loss (TEWL) (Corneometer CM 825 and Tewameter TM 210) were analysed before and after a single and 1- and 2-week period of daily application. RESULTS: After a single application, only formulations supplemented with 0.25% and 0.50% (w/w) of Aloe vera extract increased the water content of the stratum corneum, while after the 2-week period application, all formulations containing the extract (0.10%, 0.25% and 0.50%) had the same effect, in both cases as compared with the vehicle. TEWL was not modified after a single and after 1- and 2-week period of application, when compared with the vehicle. CONCLUSION: Our results show that freeze-dried Aloe vera extract is a natural effective ingredient for improving skin hydration, possibly through a humectant mechanism. Consequently, it may be used in moisturizing cosmetic formulations and also as a complement in the treatment of dry skin.  相似文献   
70.
OBJECTIVE: To examine the economic consequences of effective antihypertensive treatment using the novel vasodilating beta1-adrenoceptor antagonist nebivolol (Nebilet) from the perspective of the healthcare provider. METHODS: The evaluation was based on a postmarketing surveillance study in Germany involving 8682 moderately hypertensive patients. Using the Framingham Risk Model, the antihypertensive effectiveness of nebivolol after 6 weeks of treatment was extrapolated to estimate the reductions in 10-year risks of cardiovascular events. Data sources included direct costs for medical and invasive cardiovascular interventions in Germany, costs of therapy in the US and the UK, and estimates on the prevalence of cardiovascular events issued by the American Heart Association. RESULTS: Six-week antihypertensive treatment resulted in a DBP reduction of 13.7 mm Hg. The rate of responders, defined as those patients achieving DBP <90 mm Hg, was 70%. SBP was reduced by 26.1 mm Hg. According to the Framingham Risk Model, 313 deaths would be avoided. Coronary heart disease (CHD) could be reduced by 94 cases (from 1339 to 1245 events) and 150 strokes would be avoided (from 518 to 368 events) in a 10-year period. This reduction of 244 cardiovascular events among the 8682 patients investigated corresponded to cost savings of between Euro 250,000 and Euro 2.5 million, depending on the healthcare environment and the intervention applied. CONCLUSION: Treatment of moderately hypertensive patients with nebivolol can be considered cost effective. Nebivolol has the potential to decrease the overall long-term costs of medical care for patients with hypertension.  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