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   5358篇
  免费   377篇
  国内免费   37篇
耳鼻咽喉   64篇
儿科学   289篇
妇产科学   96篇
基础医学   689篇
口腔科学   175篇
临床医学   560篇
内科学   1209篇
皮肤病学   79篇
神经病学   475篇
特种医学   440篇
外科学   550篇
综合类   93篇
一般理论   10篇
预防医学   377篇
眼科学   92篇
药学   263篇
中国医学   1篇
肿瘤学   310篇
  2021年   39篇
  2018年   61篇
  2017年   48篇
  2016年   67篇
  2015年   53篇
  2014年   108篇
  2013年   157篇
  2012年   195篇
  2011年   223篇
  2010年   118篇
  2009年   101篇
  2008年   175篇
  2007年   232篇
  2006年   238篇
  2005年   202篇
  2004年   217篇
  2003年   208篇
  2002年   187篇
  2001年   172篇
  2000年   208篇
  1999年   145篇
  1998年   67篇
  1997年   51篇
  1996年   58篇
  1995年   83篇
  1994年   60篇
  1993年   55篇
  1992年   164篇
  1991年   157篇
  1990年   166篇
  1989年   160篇
  1988年   140篇
  1987年   126篇
  1986年   133篇
  1985年   126篇
  1984年   101篇
  1983年   86篇
  1982年   50篇
  1981年   44篇
  1980年   38篇
  1979年   78篇
  1978年   55篇
  1977年   36篇
  1976年   50篇
  1975年   42篇
  1974年   44篇
  1973年   56篇
  1972年   51篇
  1971年   41篇
  1970年   40篇
排序方式: 共有5772条查询结果,搜索用时 15 毫秒
11.
Rats with unilateral 6-hydroxydopamine lesions of substantia nigra rotate (circle) when placed, undrugged, in the environment in which they have previously been treated with apomorphine. This conditioned rotation, like the unconditioned rotation which acutely follows the administration of apomorphine, is directed away from the side with the lesion, i.e., the rotation is contralateral. Here, rats that had been administered apomorphine weeks earlier were tested, in a crossover design, for the expression of conditioned rotation following treatment with saline and with alpha-methyltyrosine. When administered four hours prior to testing, 100 mg/kg alpha-methyltyrosine significantly antagonized the expression of classically conditioned rotation. In a second group of animals, alpha-methyltyrosine had no effect on the unconditioned rotation induced by 0.05 mg/kg apomorphine.  相似文献   
12.
BACKGROUND: The effects on morbidity were examined of providing an educational intervention and a written guided self-management plan to the parents of pre-school children following a recent attendance at hospital for asthma or wheeze. METHODS: A prospective, randomised, partially blinded, controlled trial was designed at two secondary care centres. Over a 13 month period 200 children aged 18 months to 5 years at the time of admission to a children's ward or attendance at an accident and emergency department or children's (emergency) assessment unit (A&E/CAU) with a primary diagnosis of acute severe asthma or wheezing were recruited. 101 children were randomised into the control group and received usual care and 99 were assigned to the intervention group and received: (1) a pre-school asthma booklet; (2) a written guided self-management plan; and (3) two 20 minute structured educational sessions between a specialist respiratory nurse and the parent(s) and child. Subjects were assessed at 3, 6, and 12 months. The main outcomes were GP consultation rates, hospital re-admissions, and attendances at A&E/CAU. Secondary outcomes included disability score, caregivers' quality of life, and parental knowledge of asthma. RESULTS: There were no statistically significant differences between the two groups during the 12 month follow up period for any of the main or secondary outcome measures. CONCLUSIONS: These results do not support the hypothesis that the introduction of an educational package and a written guided self-management plan to the parents of pre-school children with asthma who had recently attended hospital for troublesome asthma or wheeze reduces morbidity over the subsequent 12 months.  相似文献   
13.
Truncus Arteriosus With Patent Ductus Arteriosus and Normal Aortic Arch   总被引:1,自引:0,他引:1  
In hearts with a common arterial trunk (truncus arteriosus), there is almost always an inverse development of the aortic arch and the ductus arteriosus. Truncus with a normal aortic arch and a patent ductus is a rare echocardiographic and surgical finding. In this report, we describe 2 neonates in whom truncus arteriosus with a normal aortic arch and a medium or large patent ductus was diagnosed by preoperative echocardiography (without catheterization) and confirmed intraoperatively.  相似文献   
14.
15.
In summary, we have described two patients with CRMO and psoriasis, and have reviewed the musculoskeletal manifestations associated with pustular eruptions of the palms and soles. In view of the frequent occurrence of PPP in patients with CRMO, we suggest that the occurrence of psoriasis in our two patients is more than coincidence, and that noninfectious, inflammatory lesions of bone may be another musculoskeletal manifestation of psoriasis. This rare association, as well as the association of PPP with disorders associated with new bone formation, may shed new insights on the relatively common finding of periosteal elevation associated with psoriatic arthritis and the occasional severe juxta-articular osteolytic destructive bone lesions seen in psoriatic arthritis.  相似文献   
16.
We report a patient with alcohol-induced necrotizing pancreatitis who developed a severe ileus followed by incarceration of a portion of the transverse colon within a ventral hernia. Laparotomy 9 days after the onset of symptoms revealed infarction of the transverse colon and infection of the pancreas. This is the first report of a case of acute pancreatitis that led to a strangulated ventral hernia of the colon. We believe that the enteric organisms that infected the pancreas originated in the incarcerated transverse colon.  相似文献   
17.
The hemostatic dysfunction induced by cardiopulmonary bypass is due, in part, to a platelet dysfunction evidenced by a postoperative extension of the bleeding time; it leads to increased postoperative blood loss and morbidity. This study, which was conducted in 85 patients undergoing cardiopulmonary bypass, was designed to characterize the hematologic changes during and after cardiopulmonary bypass and to elucidate the relationships between these changes, the extension of the bleeding time, and the magnitude of the postoperative nonsurgical blood loss. Variables were measured before, during, and 2, 24, 48, and 72 hours after cardiopulmonary bypass. Univariate and multivariate analyses were performed with either the 2-hour postbypass bleeding time or the 4-hour postbypass blood loss as the dependent variables. The reversal of the extension of the bleeding time in the postoperative period was accompanied by a significant increase in the mean platelet volume and by a significant increase in the level of thromboxane B2 measured in the blood shed from the site of the bleeding time determination. The postoperative bleeding time correlated with the postoperative blood loss, and both parameters were dependent on the duration of cardiopulmonary bypass. In addition, the postoperative bleeding time correlated with the skin temperature and the plasma level of D-dimer, while the postoperative blood loss also correlated with temperature and the plasma levels of C3. These data establish a direct relationship between the postoperative bleeding time, the postoperative blood loss, and temperature. They indicate that the reversal of the postoperative extension of the bleeding time is due in part to rewarming and to the release of larger platelets into the circulation, and they suggest that hyperfibrinolysis and complement activation may play an important role in the cardiopulmonary bypass-induced platelet dysfunction.  相似文献   
18.
Recently we showed that 3-alkyl-4-aminobutanoic acids are in vitro activators of brain L-glutamic acid decarboxylase (GAD) that show anticonvulsant activity. Since activation of GAD leads to increased concentrations of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in vitro, these compounds could represent a new class of anticonvulsant agents. Here it is shown that 3-alkylglutamic acid analogues also activate GAD and that all of the compounds in both series are active anticonvulsant agents against low intensity electroshock in mice. The most active compound, 3-isobutyl GABA, was tested further against maximal electroshock in mice and was shown to be very potent after both intravenous and oral administration without causing ataxia. It is not known if brain GABA levels are elevated in vivo by administration of these compounds or if the mechanism of anticonvulsant activity is related to their ability to activate GAD.  相似文献   
19.
Allograft coronary artery disease (ACAD) is the major factor limiting long-term survival of cardiac transplant recipients (CTRs). Although cyclosporine based triple drug immunosuppression has not decreased the occurrence of ACAD, some preliminary data suggests that prophylactic antilymphocyte preparations may reduce the incidence of this problem. All CTRs at Henry Ford Hospital have uniformly received prophylactic Minnesota Antilymphocyte Globulin (ALG), thereby providing a unique opportunity to investigate this hypothesis. One hundred three CTRs were followed for a median duration of 34 months with annual angiograms begun one year after transplant. Patients who died without an angiogram were considered to have ACAD based on autopsy results or if their death was clinically suspicious. Ninety-two patients underwent at least one angiogram. Fourteen patients had abnormal angiograms. Nine patients were identified as having ACAD by non-angiographic criteria. Five had autopsy proven disease, 3 died suspiciously, and 1 underwent successful re-transplantation for ACAD. By Kaplan-Meier analysis, the risk of developing ACAD was 12% in 1 year, 16% in 2 years, 22% in 3 years, 26% in 4 years, and 29% in 5 years. Risk of ACAD increased with older recipient's age, higher triglyceride levels, and diabetes, but was not affected by active CMV infection, number of acute rejection episodes, and HLA mismatching. These results suggest that prophylactic ALG reduces the occurrence of ACAD.  相似文献   
20.
Implantation response has been a critical problem following heart-lung and lung transplantation. While the precise etiology of this problem remains unclear, improvements in organ preservation would be expected to have a beneficial effect on implantation response. The time-related profile of the implantation response was studied in 20 patients who underwent heart-lung transplantation between March 1984-March 1987. In 10 operations the donors had intravenous prostaglandin E-1 pretreatment while 10 had no vasodilatation before explantation of the organs. Otherwise lung preservation and early (2 weeks) immunotherapy were similar in both groups. The implantation response was evaluated by chest films and postoperative lung functions and mechanics. Roentgenographic implantation response was evident from the first postoperative day, was less evident at the seventh postoperative day and then gradually increased during the second postoperative week. There was a tendency towards less implantation response in the PGE-1 group than in the control group, but no statistical difference was observed. Patients with severe operative bleeding problems were excluded from the study. Only peak inspiratory pressures were significantly higher in the control group than in the PGE-1 group (p less than 0.01). Other lung function studies (alveolar-capillary pO2 difference, extubation time) were not different in the groups. This study supported the hypothesis that prostaglandin E-1 may have salutary effects on graft preservation and implantation response in heart-lung transplantation. Since 1986, we have performed 16 heart-lung transplantations using graft preservation with PGE-1 and flush perfusion. Thirty-day mortality is 0% and 13 of 16 patients are surviving.  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