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   1587篇
  免费   194篇
  国内免费   4篇
耳鼻咽喉   3篇
儿科学   27篇
妇产科学   33篇
基础医学   210篇
口腔科学   19篇
临床医学   192篇
内科学   429篇
皮肤病学   20篇
神经病学   138篇
特种医学   37篇
外科学   229篇
综合类   30篇
一般理论   1篇
预防医学   110篇
眼科学   32篇
药学   218篇
肿瘤学   57篇
  2021年   24篇
  2020年   12篇
  2019年   22篇
  2018年   32篇
  2017年   24篇
  2016年   22篇
  2015年   14篇
  2014年   33篇
  2013年   46篇
  2012年   60篇
  2011年   64篇
  2010年   37篇
  2009年   34篇
  2008年   76篇
  2007年   71篇
  2006年   76篇
  2005年   74篇
  2004年   65篇
  2003年   64篇
  2002年   58篇
  2001年   56篇
  2000年   54篇
  1999年   55篇
  1998年   34篇
  1996年   15篇
  1994年   15篇
  1993年   17篇
  1992年   44篇
  1991年   38篇
  1990年   30篇
  1989年   23篇
  1988年   36篇
  1987年   39篇
  1986年   35篇
  1985年   25篇
  1984年   22篇
  1983年   14篇
  1982年   20篇
  1981年   13篇
  1980年   13篇
  1979年   29篇
  1978年   14篇
  1977年   17篇
  1975年   17篇
  1974年   17篇
  1973年   14篇
  1970年   14篇
  1969年   12篇
  1968年   12篇
  1967年   11篇
排序方式: 共有1785条查询结果,搜索用时 312 毫秒
1.
The purpose of the study was to compare an interview measure of quality of object relations to questionnaire and interview measures of recent interpersonal functioning with respect to the prediction of therapeutic alliance and psychotherapy outcome. The sample consisted of 64 patients who had received approximately 20 sessions of short-term individual psychotherapy within a controlled, clinical-trial investigation. Ratings of therapeutic alliance were provided independently by the patient and the therapist after each session. Outcome measures, which were provided by three sources (patient, therapist, and independent assessor), covered the areas of interpersonal functioning, psychiatric symptomatology, self-esteem, and life satisfaction. Quality of object relations, which characterizes the patient's lifelong pattern of relationships, was the best predictor. It was significantly related to patient-rated and therapist-rated therapeutic alliance and to patient improvement of both general symptomatology and specific target problems. The study also replicated previous studies that have reported significant relationships between therapeutic alliance and therapy outcome. The advantages of pretherapy predictors of therapy outcome, such as quality of object relations, are discussed.  相似文献   
2.
3.
4.
OBJECTIVE: To evaluate the relative risk for peptic ulcer disease that is associated with the use of nonaspirin nonsteroidal anti-inflammatory drugs. DESIGN: Nested case-control study. SETTING: Tennessee Medicaid program. PARTICIPANTS: Medicaid enrollees 65 years of age or older were included in the study. The 1415 case patients had been hospitalized for confirmed peptic ulcer disease at some point from 1984 through 1986. The 7063 control persons represented a stratified random sample of other Medicaid enrollees. MEASUREMENTS AND MAIN RESULTS: The estimated relative risk for the development of peptic ulcer disease among current users of nonaspirin nonsteroidal anti-inflammatory drugs, compared with that among nonusers, was 4.1 (95% CI, 3.5 to 4.7). For current users, the risk increased with increasing dose, from a relative risk of 2.8 (CI, 1.8 to 4.3) for the lowest to a relative risk of 8.0 (CI, 4.4 to 14.8) for the highest dose category. The risk was greatest in the first month of use (relative risk, 7.2; CI, 4.9 to 10.5). If the association is fully causal, 29% of peptic ulcers in the study sample resulted from the use of these drugs, and the excess risk associated with such use was 17.4 hospitalizations for ulcer disease per 1000 person-years of exposure. CONCLUSIONS: These data support other findings indicating that a clinically significant risk for serious ulcer disease is associated with the use of nonaspirin nonsteroidal anti-inflammatory drugs. The data show that this risk increases with dose and recency of use and that use of these drugs may be responsible for a large proportion of peptic ulcer disease among elderly persons.  相似文献   
5.
1. This study examined whether pretreatment of rabbits with infusions of prostaglandin E1 (PGE1) or prostaglandin E0 (PGE0) (which were terminated prior to the onset of ischaemia) reduce myocardial infarct size arising from coronary artery occlusion (60 min) and reperfusion (120 min). In addition, we investigated whether the observed cardioprotective effects of these two prostaglandins were due to the activation of ATP-sensitive potassium (KATP) channels. 2. In the anaesthetized rabbit, infarct size (expressed as a percentage of the area at risk) after 60 min of coronary artery occlusion followed by 2 h of reperfusion was 59 +/- 4% (n = 10). PGE1 or PGE0 treatment (1.0 micrograms kg-1 min-1), administered as 1 h pretreatments (0.05 ml min-1, i.v.), significantly reduced infarct size to 44 +/- 6% (n = 6) or 42 +/- 1% (n = 6), respectively. PGE1 or PGE0 pretreatment resulted in a significant reduction in mean arterial blood pressure, which returned to baseline within 15 min of discontinuation of the infusion (i.e. prior to LAL ligation). 3. The reduction in infarct size afforded by PGE1 was abolished by pretreatment of rabbits with the KATP channel blockers, glibenclamide (60 +/- 4%; n = 8) or 5-hydroxydecanoate (58 +/- 6%; n = 6). Similarly, glibenclamide also largely attenuated the reduction in infarct size afforded by PGE0 (52 +/- 3%; n = 8). 4. We propose that a 1 h pretreatment of PGE1 or PGE0 reduces infarct size by activating protein kinase C resulting in the opening of KATP channels.  相似文献   
6.
7.
8.
Diaspirin cross-linked haemoglobin (DCLHb) is a new oxygen carrying blood substitute with vasoactive properties. Vasoactive properties may be mediated via high affinity binding of nitric oxide by the haem moiety. Using a rodent model of head injury combined with ischaemia, we studied the effects of DCLHb on cerebral blood flow (CBF) and intracranial pressure (ICP). Twenty anaesthetized rats were allocated randomly to receive treatment with DCLHb 400 mg kg-1 i.v. or placebo (oncotically matched plasma protein substitute 4.5% i.v.). To produce diffusely increased ICP, after a severe weight drop injury, all animals underwent a 30-min period of bilateral carotid ligation combined with a period of induced hypotension. After reperfusion, DCLHb or placebo was infused and the animals instrumented for measurement of intraventricular ICP and CBF in the region of the sensorimotor cortex using the hydrogen clearance technique. Mean arterial pressure (MAP), ICP, cerebral perfusion pressure (CPP) (CPP = MAP - ICP) and CBF were measured 4 h after injury in all animals. DCLHb significantly reduced ICP from mean 13 (SEM 2) to 3 (1) mm Hg (P < 0.001), increased CPP from 52 (8) to 95 (6) mm Hg (P < 0.001) and increased CBF from 21 (2) to 29 (2) ml 100 g-1 min-1 (P = 0.032). We conclude that DCLHb improved CPP without a reduction in CBF in a rodent model of post-traumatic brain swelling.   相似文献   
9.
1. Angiotensin II (AII) causes contraction of isolated rings of human saphenous vein, responses that are attenuated by the presence of functional endothelium. In this study, we have investigated the mechanisms controlling the release by AII of two endothelial-derived vasorelaxants, prostacyclin (PGI2) and nitric oxide (NO). 2. Myotropic and biochemical changes were measured in response to AII. The biochemical responses measured were the output of PGI2 (as 6-oxo-PGF1 alpha) and of NO (as cyclic GMP). Inhibitors of cyclo-oxygenase (COX; piroxicam) or NO synthase (NOS; L-NAME), were added to the system to determine the influence of endogenous prostaglandins and NO on both myotropic and biochemical responses. Furthermore, to mimic the effects of endogenous, PGI2 or NO, exogenous forms of these relaxants were added, during inhibition of their endogenous release. 3. Contractions of the rings of saphenous vein in response to AII (1-100 nM) were unaffected by treatment with either piroxicam (5 microM) or L-NAME (200 microM) individually. However, when these two inhibitors were used together, there was an increase in the contractions in response to AII. 4. Biochemical analyses revealed that during stimulation by AII, levels of PGI2 and NO were enhanced when synthesis of the other vasodilator was inhibited, suggesting that endogenous NO inhibits PGI2 synthesis and endogenous, PGI2 or another vasorelaxant PG can inhibit NO synthesis. 5. Exogenous PGI2 (as iloprost) or NO (from glyceryl trinitrate) inhibited the increased output of endogenous NO or PGI2 respectively. 6. These results demonstrate the presence, in human saphenous vein, of a mechanism which ensures that levels of vasodilatation are maintained through a compensatory increase in one relaxant agonist when output of the other is decreased. If present in vivo such a mechanism would be important in maintaining saphenous vein graft patency as both PGI2 and NO are not only vasodilators, but inhibit platelet aggregation and myoinitimal hyperplasia, processes implicated in degeneration of graft function.  相似文献   
10.
Using the artificial beta-cell (Biostator), we determined the insulin requirements in five nonobese type I (insulin-dependent) diabetic subjects who received isocaloric 40 and 60% mixed-carbohydrate diets in a crossover randomized fashion for 4 days, each day consisting of four equal meals. This was followed on day 5 by a "Big Mac Attack" lunch consisting of a Big Mac, french fries, and milk shake. Insulin requirements to maintain normoglycemia were calculated for each 24-h period and for the 2 h after each meal. The mean 24-h insulin requirements to maintain normoglycemia was greater for the 60% carbohydrate diet than the 40% diet. Although the four meals were of equal size, in all patients the insulin required to cover breakfast greater than lunch greater than dinner greater than or equal to snack. Expressed as milliunits per kilocalorie, the amount of insulin to cover breakfast was greater for the 60% (P less than .05) than the 40% carbohydrate diet and greater for breakfast than the other meals (P less than .01). Insulin requirements for the Big Mac (43% carbohydrate) were 58% greater than for the 40% carbohydrate diet, even after correction for caloric differences. In summary, 1) increasing dietary carbohydrate from 40 to 60% results in an increased insulin requirement for meals only; 2) insulin requirements are greater in the morning than in the evening, even when meal size is constant; and 3) very large meals with high fat and carbohydrate content result in a major increase in insulin requirement. These data indicate that diet has an important impact on insulin requirements in diabetes.  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