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   3238篇
  免费   106篇
  国内免费   19篇
耳鼻咽喉   24篇
儿科学   40篇
妇产科学   55篇
基础医学   439篇
口腔科学   43篇
临床医学   330篇
内科学   697篇
皮肤病学   17篇
神经病学   359篇
特种医学   91篇
外科学   554篇
综合类   5篇
一般理论   1篇
预防医学   177篇
眼科学   27篇
药学   260篇
中国医学   2篇
肿瘤学   242篇
  2024年   12篇
  2023年   15篇
  2022年   25篇
  2021年   59篇
  2020年   26篇
  2019年   39篇
  2018年   73篇
  2017年   27篇
  2016年   46篇
  2015年   63篇
  2014年   99篇
  2013年   163篇
  2012年   218篇
  2011年   253篇
  2010年   115篇
  2009年   122篇
  2008年   242篇
  2007年   238篇
  2006年   240篇
  2005年   218篇
  2004年   222篇
  2003年   208篇
  2002年   226篇
  2001年   36篇
  2000年   32篇
  1999年   31篇
  1998年   49篇
  1997年   45篇
  1996年   24篇
  1995年   20篇
  1994年   21篇
  1993年   12篇
  1992年   14篇
  1990年   10篇
  1989年   9篇
  1988年   4篇
  1987年   7篇
  1986年   6篇
  1985年   4篇
  1984年   10篇
  1983年   9篇
  1981年   3篇
  1980年   4篇
  1915年   9篇
  1911年   5篇
  1910年   3篇
  1908年   5篇
  1906年   3篇
  1905年   3篇
  1903年   4篇
排序方式: 共有3363条查询结果,搜索用时 15 毫秒
71.
72.
OBJECTIVE: To study management of hypertension in the elderly in a large population-based study and to evaluate the prevalence of hypertension and factors related to awareness, treatment, and control. DESIGN: The Three City study, a population-based study among 9693 non-institutionalized individuals aged 65 years and over. METHODS: Blood pressure was measured with an automated electronic device, and treatment assessed, during home interview. Hypertension was defined by a mean blood pressure of two measurements superior to or equal to 160/95 mmHg and/or the intake of antihypertensive medications. RESULTS: In the final working sample of 9090 people, 62% were hypertensive. More than two-thirds were aware of their hypertension and 81% were treated with antihypertensive drugs. Among 4573 treated hypertensive participants, 35% had a blood pressure over 160/95 mmHg and 69% over 140/90 mmHg. Women were more frequently aware of their hypertension, more frequently treated, and more frequently controlled than men. A history of cardiovascular disease, high body mass index, diabetes and high frequency of visits to the general practitioner were related to higher percentages of awareness and treatment. Among treated hypertensive patients, those with a history of cardiovascular events or who visited their general practitioner more often or who more often had their blood pressure measured were more frequently controlled. Awareness was strongly associated with treatment, but was inversely related to control of hypertension among treated hypertensive patients. CONCLUSIONS: Management of hypertension, and particularly its control among treated hypertensive patients, needs to be improved in people aged 65 years and over.  相似文献   
73.
The question as to whether the firing patterns of low- and high-threshold motor units in the extensor carpi radialis muscles are affected differently by group I afferents from the wrist flexors depending on the motor task being performed was investigated in six subjects. The motor units were voluntarily activated during a task consisting of either selectively contracting the wrist extensor muscles or co-activating the wrist and finger antagonist muscles by clenching the hand around a manipulandum. The motor units (n=40) were identified on the basis of their firing thresholds, their macro-potential areas, and their twitch contraction times. The effects on the motor-unit tonic activity of stimulating the wrist flexor afferents were assessed in terms of the changes in the firing probability, which were analysed after computing peri-stimulus time histograms using the cumulative sum procedure. Median nerve stimulation induced four main changes in the tonic firing pattern of the extensor motor units. An early, short-lasting increase in the firing probability (event E1) was found to occur in the high-threshold motor units, either in both tasks (6/13) or only during hand clenching (2/13). A short-latency decrease in the firing probability (event E2) was found to occur in all the motor units, the amount of which increased from the fast- to slowly contracting motor units, especially during hand clenching. A later decrease (event E3) followed by a large, late increase (event E4) in the tonic activity of the motor units was found to occur in all the motor units, without any task-dependent effects. All these various events were consistently observed in 12 pairs of motor units, each consisting of one slowly and one fast-contracting motor unit, which were tested simultaneously. These findings suggest that median nerve stimulation may selectively alter the tonic firing patterns of identified extensor motor units, depending on their functional characteristics (recruitment threshold, motor unit macro-potential area, contraction time) rather than on the excitatory drive to the motoneurone pool. The possible origins of these various events are discussed, and it is argued that, in the wrist extensor and flexor muscles that act as synergists during manipulatory finger movements and gripping tasks, the spinal pathways which assist the voluntary command may selectively modulate the firing patterns of identified motor units, to fit the requirements of the on-going motor task.  相似文献   
74.

Background

We conducted a monocentric retrospective study of patients with myelodysplastic syndromes (MDS) and autoimmune or inflammatory disorders (AIMs) and a literature review. We analyzed the association with subgroups of the WHO 2016 MDS classification and patient's survival in a case control study. Risk factors associated with survival were analyzed by uni- and multivariate analysis.

Results

From all MDS patients 11% presented with AIMs. These were heterogeneous and the most frequent where polyarthritis (25%) and autoimmune cytopenias (17%). No difference for frequency and type of AIMs was observed for the WHO 2016 MDS subgroups (p?=?.3). In the case control study WHO classification, karyotype abnormalities, IPSS-R and IPSS were similar in both groups. The overall survival from MDS diagnosis was better in the group with AIMs [10.3?±?0.6 (IC95% 6.2–12.9) versus 4.8?±?1.1?years (IC95% 4.2–8.7), p?=?.04]. The better survival was restricted to MDS with low or intermediate-1 IPSS [11.1?±?1.5 (IC95% 9.9-NR) versus 8.7?±?1.3?years (IC95% 4.8–10.3), p?=?.006]. The better survival was only observed when AIMs diagnosis was timely associated or appeared after MDS diagnosis (p?=?.04). Factors associated with a better overall survival and survival without AML were steroid dependence [respectively HR?=?0.042, p?=?.003, (IC95% 0.005–0.33) and HR?=?0.07, p?=?.002, (IC95% 0.013–0.39)], a diagnosis of AIMs and MDS timely associated [respectively HR?=?0.05, p?=?.009, (IC95% 0.006–0.478) and HR?=?0.1, p?=?.008, (IC95% 0.018–0.54)] or a diagnosis of AIMs after MDS [respectively HR?=?0.024, p?=?.009, (IC95% 0.001–0.39) and HR?=?0.04, p?=?.008, (IC95% 0.003–0.43)].

Conclusion

Autoimmune and inflammatory diseases associated to MDS are heterogeneous. AIMs diagnosed after or concomitantly to MDS seems associated with a better survival. Prospective studies are necessary to demonstrate that autoimmunity is associated to a better control of the MDS clone.  相似文献   
75.
We report two cases of giant hemangioma of the liver revealed by a clinico-biological syndrome including fever, right upper quadrant pain and a biological inflammatory syndrome, whereas liver function tests and blood cell count were normal. This clinical presentation may help in the diagnosis of giant hemangioma of the liver.  相似文献   
76.
    
OBJECTIVEDepression is common in people with diabetes, but data from developing countries are scarce. We evaluated the prevalence and risk factors for depressive symptoms in patients with diabetes using data from the International Diabetes Management Practices Study (IDMPS).RESEARCH DESIGN AND METHODSIDMPS is an ongoing multinational, cross-sectional study investigating quality of care in patients with diabetes in real-world settings. Data from wave 5 (2011), including 21 countries, were analyzed using the 9-item Patient Health Questionnaire (PHQ-9) to evaluate depressive symptoms. Logistic regression analyses were conducted to identify risk factors of depressive symptoms.RESULTSOf 9,865 patients eligible for analysis, 2,280 had type 1 and 7,585 had type 2 diabetes (treatment: oral glucose-lowering drugs [OGLD] only, n = 4,729; OGLDs plus insulin, n = 1,892; insulin only, n = 964). Depressive symptoms (PHQ-9 score ≥5) were reported in 30.7% of those with type 1 diabetes. In patients with type 2 diabetes, the respective figures were 29.0% for OGLDs-only, 36.6% for OGLDs-plus-insulin, and 46.7% for insulin-only subgroups. Moderate depressive symptoms (PHQ-9 score 10–19) were observed in 8–16% of patients with type 1 or type 2 diabetes. Female sex, complications, and low socioeconomic status were independently associated with depressive symptoms. In type 1 diabetes and in the type 2 diabetes OGLDs-only group, depression was associated with poor glycemic control.CONCLUSIONSDepressive symptoms are common in patients with diabetes from developing countries, calling for routine screening, especially in high-risk groups, to reduce the double burden of diabetes and depression and their negative interaction.  相似文献   
77.
78.
79.
Lipoprotein data from 9477 subjects, covering a wide range of total plasma cholesterol levels, were used to examine the validity of the Friedewald formula for estimating plasma concentrations of low-density lipoprotein cholesterol (LDL-C) using high-density lipoprotein cholesterol (HDL-C) and triglyceride (TG) concentrations. Values of LDL-C obtained from the Friedewald formula were compared with values of LDL-C derived from preparative ultracentrifugation used as a reference method. We found that the bias associated with the Friedewald formula was not related to plasma LDL-C levels and was smaller than −4.0% even for plasma LDL-C values <3.0 mmol/l. Moreover, in the subgroup of individuals with plasma TG levels ≤4.5 mmol/l, the Friedewald formula underestimated LDL-C levels with a bias between −3.1% and −1.9% according to TG quartiles. Interestingly, the Friedewald formula showed no significant bias in patients with plasma TG levels between 4.51 and 8.82 mmol/l, suggesting that the calculated LDL-C are reliable and could be clinically useful in patients with plasma TG levels higher than 4.5 mmol/l which is the reference cut-point value used by most clinical laboratories. Finally, multiple regression analyses showed that the very low-density lipoprotein cholesterol (VLDL-C)/TG ratio represented nearly 63% (P < 0.0001) of the variance of the bias associated with the Friedewald formula. We concluded that the Friedewald formula may be reliable at low LDL-C levels and at TG levels up to 9 mmol/l but may be used with caution when the VLDL-C/TG ratio is high as observed in patients with type III dysbetalipoproteinemia.  相似文献   
80.
The present study compared short-term effects of the AT(1)-receptor antagonist, irbesartan with the angiotensin-converting enzyme (ACE) inhibitor, enalapril on systemic haemodynamics and cardiac remodelling in post-myocardia-infarcted (MI) rats. MI Sprague-Dawley rats were orally treated for 4 weeks with irbesartan (50 mg/kg/day) or enalapril (10 mg/kg/day). Then, cardiac and systemic haemodynamics were measured. Compared with the sham-operated group, left ventricular end-diastolic pressure (LVEDP), diastolic pressure (LVDP), heart weight to body weight ratio were all significantly increased in the MI group while the LV contractility (dP/dt) and pulsatile arterial pressure were significantly reduced. Both drugs reduced the elevated LVEDP and LVDP and prevented cardiac hypertrophy. Furthermore, irbesartan attenuated the right shift of the pressure-volume curves, prevented postinfarction-induced increase in urinary cyclic guanosine monophosphate and reduced urinary aldosterone excretion. Although both drugs were able to prevent further cardiac hypertrophy and improved cardiac filling pressure, only irbesartan limited LV dilatation. These data indicate that blockade of the renin-angiotensin system at the level of AT1 receptors may have a better cardioprotective benefit than reducing angiotensin II levels by ACE inhibition.  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