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   97708篇
  免费   11301篇
  国内免费   4855篇
耳鼻咽喉   984篇
儿科学   1920篇
妇产科学   1058篇
基础医学   6469篇
口腔科学   2227篇
临床医学   12883篇
内科学   10877篇
皮肤病学   1277篇
神经病学   3325篇
特种医学   4044篇
外科学   9363篇
综合类   21891篇
现状与发展   13篇
一般理论   11篇
预防医学   13067篇
眼科学   1133篇
药学   9749篇
  119篇
中国医学   8451篇
肿瘤学   5003篇
  2024年   491篇
  2023年   1475篇
  2022年   2808篇
  2021年   3683篇
  2020年   3339篇
  2019年   1894篇
  2018年   2377篇
  2017年   2910篇
  2016年   2405篇
  2015年   3990篇
  2014年   4929篇
  2013年   6455篇
  2012年   8028篇
  2011年   8381篇
  2010年   7559篇
  2009年   6926篇
  2008年   6775篇
  2007年   6572篇
  2006年   5798篇
  2005年   4617篇
  2004年   3356篇
  2003年   2780篇
  2002年   2309篇
  2001年   2185篇
  2000年   1689篇
  1999年   1021篇
  1998年   549篇
  1997年   548篇
  1996年   564篇
  1995年   486篇
  1994年   387篇
  1993年   374篇
  1992年   473篇
  1991年   444篇
  1990年   459篇
  1989年   431篇
  1988年   382篇
  1987年   358篇
  1986年   344篇
  1985年   344篇
  1984年   247篇
  1983年   219篇
  1982年   151篇
  1981年   153篇
  1980年   137篇
  1979年   177篇
  1978年   151篇
  1977年   137篇
  1976年   132篇
  1971年   131篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The new oral hypoglycemic agent SDZ 51641 was evaluated in nondiabetic rats and a rat model of human non-insulin-dependent diabetes mellitus. Diabetes was induced with a single injection of 37.5 mg/kg streptozocin, and the rats exhibited hyperglycemia in the fed state with normal insulin levels. Treatment of nondiabetic animals with 100 mg/kg SDZ 51641 given orally significantly decreased serum glucose and ketone levels within 4 h without affecting insulin levels. Nonesterified fatty acids increased more than twofold during the same period. Its effect on ketone and fatty acid levels suggests that SDZ 51641 acts as an inhibitor of fatty acid oxidation. Diabetic rats treated with SDZ 51641 exhibited a significant acute hypoglycemic response, which was more pronounced after 3 days of treatment. The compound also significantly decreased serum cholesterol and triglyceride levels 27 and 53%, respectively. When endogenous hepatic glucose production was assessed in nondiabetic and diabetic animals via continuous infusion of [3-3H]glucose, we found that hepatic glucose production was elevated 43% in diabetic compared with control animals. When diabetic rats were treated with 100 mg/kg SDZ 51641, hepatic glucose production decreased to normal levels within 6 h. Hyperinsulinemic-euglycemic clamp studies indicated that SDZ 51641 had no effect on insulin-stimulated glucose utilization. Measurement of [1-14C]oleate oxidation in isolated hepatocytes demonstrated that SDZ 51641 inhibited long-chain fatty acid oxidation in a concentration-dependent manner. The compound was ineffective at inhibiting long-chain fatty acid oxidation in epitrochlearis or soleus muscles.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
102.
CHARACTERISTICS OF MEMBRANE TRANSPORT PROCESSES OF MACULA DENSA CELLS   总被引:1,自引:0,他引:1  
1. Macula densa (MD) cells are located within the thick ascending limb (TAL) and have their apical surface in contact with tubular fluid and their basilar region in contact with the glomerulus. These cells sense changes in luminal fluid sodium chloride concentration ([NaCl]) and transmit signals resulting in changes in vascular resistance (tubuloglomerular feedback) and renin release. 2. Current efforts have focused on understanding the cellular transport mechanisms of MD cells. Progress in this area has benefited from the use of the isolated perfused TAL-glomerular preparation, which permits direct access to MD cells. 3. Using microelectrodes to measure basolateral membrane potential (VBL) of MD cells, it was found that VBL was very sensitive to changes in luminal fluid [NaCl]. As [NaCl] was elevated from 20 to 150mmol/L, VBL was found to depolarize by over 30 mV. 4. Basolateral membrane potential measurements were also used to identify an apical Na+: 2CI?: K+ cotransport pathway in MD cells that is the major pathway for NaCl entry into these cells. 5. Other work identified a basolateral chloride channel that is presumed to be responsible for changes in VBL during alterations in luminal [NaCl]. This channel, which is the predominant conductance across the basolateral membrane, may be regulated by intracellular Ca2+ and cAMP. 6. An apical Na+: H+ exchanger in MD cells was detected by measuring changes in intracellular pH using the fluorescent probe 2′,7′-bis-(2-carboxyethyl)-5(and-6) carboxyfluorescein. 7. Using patch-clamp techniques, a high density of pH- and Ca2+-sensitive K+ channels was observed at the apical membrane of MD cells. 8. Other studies found that, at the normal physiological conditions prevailing at the end of the TAL (luminal [NaCl] of 20–60 mmol/L), reabsorption mediated by MD cells is very sensitive to changes in luminal [NaCl].  相似文献   
103.
A retrospective review was conducted of 22 human immunodeficiency virus type 1 (HIV-1)-infected children under 13 years of age presenting to an inner city pediatric emergency department to determine their clinical manifestations of disease and utilization of emergency department services. When compared with a population of 78 normal children, the infected children were more likely to present with cough, difficulty in breathing, and lethargy. Pneumonia, diarrhea, and dehydration were more common diagnoses in the infected children, who were more likely to be admitted, had more invasive procedures, and required more professional staff to provide care. There was no significant difference in the frequency of visits (visits/month of age) when comparing the two groups. As expected, the infected children presented with problems associated with pediatric HIV-1 infection. Our results suggest that HIV-1-infected children require an increased level of care in the emergency department and subsequent admission to the hospital. These children did not visit the emergency department more frequently than the controls. This may be the result of an active outpatient HIV clinic in our hospital, which is available to both scheduled and unscheduled patients.  相似文献   
104.
The development and implementation of effective community support systems are goals of many public mental health authorities who are attempting to shift the focus and dollars for mental health services from inpatient to community care. This article presents the results of a survey which asked 90 community mental health agency case managers to assess the community support and residential needs of over 1400 of their clients. Medication monitoring and therapy were rated high priority needs. Psychosocial treatment, day and vocational activities also ranked high. Survey responses regarding residential services indicated a need for more supported and supervised options.The study reported was a collaborative effort by county and agency staff.  相似文献   
105.
Research shows that clients with automatic thoughts (dysfunctional thinking) often do not think of alternative explanations in relation to negative events. Furthermore, these automatic thoughts are characterized by a broad global, self-evaluative and ambiguous nature that could make disputing (or changing the ways they think) the most difficult part of the therapeutic process. This paper proposes a two-stage practise-based disputing model, guided by research, that aims to 'bring' an automatic thought to a specific, objective, quantifiable and concrete level at which not only is the particular aspect(s) of the automatic thought that causes emotional disturbances finely focused, but the disputing is also likely to be effective and manageable. Furthermore, it will also generate alternative explanations that are helpful in reducing emotional disturbances and in facilitating problem solving approach. In this paper, the authors use a case example to discuss the rationale that underpins the conceptualization of the model and to illustrate the process in which the strategies of the model are effectively used.  相似文献   
106.
Narrative and procedural discourse in temporal lobe epilepsy.   总被引:2,自引:0,他引:2  
It is well established that some individuals with temporal lobe epilepsy (TLE) demonstrate language deficits at the single word level. However, discourse production rarely has been examined quantitatively within this group. This study compared adult TLE patients with an early seizure onset (< or = age 14 years, n = 27) to a control group (n = 28) on narrative and procedural discourse tasks. As a group, the TLE patients performed normally on the procedural discourse task, but differed significantly from the controls on several narrative discourse variables. At the individual level, 30% of the TLE patients versus 4% of the controls demonstrated impaired discourse ability (p and 0.01). Within this early onset TLE group, discourse performance was not associated with demographic or seizure history variables. Considering the cognitive domain, discourse performance correlated significantly with working memory. In summary, mild discourse dysfunction was present in a significant minority of early onset TLE patients, but this deficit was not closely associated with other language measures. Discourse ability and its neuropsychological, neuroanatomical and conversational speech correlates deserve further study in TLE patients.  相似文献   
107.
108.
This study set out to compare the long-term palatability of three oral sip-feed supplements. Sixty patients with various malignancies were randomized to receive one of three products—Build-Up, Fortimel and Fortisip. Participants were encouraged to take as much of the supplements each day for as long as they could manage. At the initial tasting, palatability and acceptability of the products was recorded and this was repeated throughout the trial period. Patients' reasons for discontinuing the trial were noted.
Build-Up was found to be the best-tolerated product of the three. It was taken for a significantly longer time than either Fortimel or Fortisip. There was an indication that Build-Up was more acceptable at the initial tasting than Fortisip but not Fortimel. A smaller proportion of patients stopped taking Build-Up due to flavour-related reasons compared to Fortisip but there was no significant difference between Build-Up and Fortimel. In all, 54% of the patients discontinued the trial for flavour-related reasons. Thirty-five per cent found that the sip-feeds they had been allotted unpalatable at the initial tasting, while 19% stopped the trial due to 'flavour fatigue'. Only 10% of the sample continued taking their allotted product for 90 days or more.  相似文献   
109.
Aim To elicit nurses' accounts of their involvement with nursing research and their interpretations of the meaning of these projects for their practice.
Background The links between research and practice development in health care are poorly understood and require further exploration in the light of the emerging research and development agenda within the National Health Service.
Methods Semi-structured interviews were conducted with 15 qualified nurses working on a Nursing Development Unit. The interviews were tape recorded, transcribed and analysed thematically.
Findings Data analysis identified two distinct groups—a core group of nurses actively engaged in the research projects and a peripheral group involved in data collection. The characteristics of the core group mirror the characteristics of those involved in non-research-based practice development activities.
Conclusions Engaging in research activities does not always result in the development of practice, however, there appears to be a link between practice development and critical thinking.  相似文献   
110.
原发性骨质疏松症 (Op)是骨构建和骨重建中 ,骨形成和骨吸收恒常调节失衡引发的一种缓慢的、渐进的骨吸收亢进症 ,是一类综合征。多种病因可以引起 ,现今一般认为和机体遗传、个体生活习惯、生理状态与生存环境等多种因素综合影响有关。因Op病因的多源性和发病机理的复杂性 ,现今尚在不断阐明中 ,多主张综合治疗处理。凡是骨密度(BMD)有明显减低或骨吸收生化标志有明显上升者 ,无论伴有或不伴有非暴力性骨折 ,均应给予治疗处理。一、Op的治疗原则和许多慢性非传染性流行性疾病类似 :(1 )去除病因 ,阻止骨量减少和骨质量劣化进程。 (2 )增…  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