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   1140篇
  免费   75篇
  国内免费   1篇
耳鼻咽喉   4篇
儿科学   42篇
妇产科学   15篇
基础医学   158篇
口腔科学   24篇
临床医学   159篇
内科学   232篇
皮肤病学   3篇
神经病学   156篇
特种医学   35篇
外科学   137篇
综合类   4篇
预防医学   117篇
眼科学   2篇
药学   61篇
肿瘤学   67篇
  2023年   4篇
  2022年   5篇
  2021年   14篇
  2020年   7篇
  2019年   16篇
  2018年   19篇
  2017年   19篇
  2016年   20篇
  2015年   18篇
  2014年   21篇
  2013年   49篇
  2012年   48篇
  2011年   56篇
  2010年   32篇
  2009年   26篇
  2008年   62篇
  2007年   62篇
  2006年   79篇
  2005年   70篇
  2004年   70篇
  2003年   94篇
  2002年   68篇
  2001年   32篇
  2000年   19篇
  1999年   17篇
  1998年   12篇
  1997年   13篇
  1996年   14篇
  1995年   10篇
  1994年   6篇
  1993年   11篇
  1992年   18篇
  1991年   18篇
  1990年   8篇
  1989年   12篇
  1988年   14篇
  1987年   16篇
  1986年   16篇
  1985年   11篇
  1984年   10篇
  1983年   7篇
  1982年   8篇
  1981年   16篇
  1979年   12篇
  1978年   5篇
  1974年   5篇
  1972年   7篇
  1971年   5篇
  1970年   10篇
  1965年   3篇
排序方式: 共有1216条查询结果,搜索用时 15 毫秒
1.
After admission to hospital for bed rest, 200 women with multiple pregnancies were randomly allocated to receive either 4 mg of salbutamol orally five times daily, or to receive no drug. After an average of 6 weeks treatment, no difference between the experimental groups could be detected with respect to duration of gestation, birthweight or any other of the outcomes of pregnancy observed.  相似文献   
2.
Activities of the xenobiotic metabolizing enzymes were measured in the liver, kidney, duodenum and lung microsomes and cytosol fractions of Wistar rats after subchronic administration of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), a potent bacterial mutagen in chlorinated drinking water. MX was administered by gavage at the dose level of 30 mg/kg for 18 weeks (low dose), or at the dose level which was raised gradually from 45 mg/kg for 7 weeks via 60 mg/kg for 2 weeks to a clearly toxic dose of 75 mg/kg for 5 weeks (high dose). Microsomal and cytosolic preparations were made and the activities of 7-ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-dealkylase (PROD), NADPH-cytochrome-c-reductase, UDP-glucuronosyltransferase (UDPGT) and glutathione-S-transferase (GST) were measured. Kidneys were affected most. A dose-dependent decrease was observed in EROD (90% in males, 80% in females at the high dose) and in PROD (58% in females, at the high dose) in kidneys. An increase was, however, detected in kidney NADPH-cytochrome-c-reductase (66% in females at high dose), UDPGT (89% in males and 97% in females at high dose) and GST activities (56% in males and 50% in females at high dose). MX caused only a few changes in the enzyme activities of the liver. The EROD activity was decreased 25% to 37%, both in the livers of males and females, but the total content of P450s was not altered. Hepatic GST activity was elevated in females in a dose-dependent manner (31% and 44%). GST activity was elevated in duodenum in females (59%) at the high dose. There were no marked changes in the enzyme activities in the lungs. MX was a weak inhibitor of EROD activity both in the liver and kidney microsomes in vitro, decreasing the EROD activity by 53% and 43%, respectively at the concentration of 0.9 mM. The results indicate that MX decreases the activity of phase I metabolism enzymes, but induces phase II conjugation enzyme activities, particularly in kidneys in vivo. It is possible that these changes contribute to metabolism of MX in kidneys and renders them susceptible to MX in the course of repeated exposure.  相似文献   
3.
Myelin basic protein antibodies in catatonic schizophrenia   总被引:1,自引:0,他引:1  
Myelin basic protein (MBP) antibodies were determined by solid-phase radioimmunoassay in the serum and cerebrospinal fluid of 10 patients with catatonia, 10 patients with other forms of schizophrenia, and 10 psychiatrically healthy controls. The mean counts per minute (cpm) value of serum anti-MBP antibody of the catatonia group was significantly higher than that of the patients with other forms of schizophrenic psychoses (p less than .05). No significant differences were observed among the cpm values of the CSF specimens from the three patient groups. The hypothesis of a central virus-induced immunologic aberration in catatonic schizophrenia is discussed.  相似文献   
4.
We evaluated the effects of isoflurane anaesthesia and induced hypotension in 33 neurosurgical patients by electrocardiographic monitoring and serial cardiac enzyme measurements. An electrocardiogram (ECG) and serum enzymes were obtained preoperatively, intraoperatively and postoperatively in the recovery room and for three consecutive days. ECG leads II, V1 and V5 were monitored continuously during anaesthesia. Patients who had had a subarachnoid haemorrhage and a high incidence of abnormal preoperative ECG (42 per cent). Ten patients developed ECG changes intraoperatively, but these changes were unrelated to isoflurane-induced hypotension. Fifty-three per cent of patients developed an abnormal postoperative ECG. These abnormalities consisted mostly of nonspecific ST segment or T wave changes. At no time was there an elevation in cardiac enzyme activity. We found that nonspecific ECG changes are relatively common in patients undergoing vascular neurosurgical procedures. There was no enzymatic evidence of myocardial infarction and we can only speculate that these ECG changes are related to intracranial surgical manipulation.  相似文献   
5.
The glucose analog (18)F-FDG is commonly used to quantify regional glucose uptake in vivo. The aim of this study was to test whether the analysis of plasma (18)F-FDG kinetics could be used to estimate endogenous glucose production (EGP) and the total rate of appearance (Ra), total rate of disappearance (Rd), and the metabolic clearance rate (MCR) of glucose. METHODS: Fourteen pigs were coinjected with (18)F-FDG and 6,6-(2)H-glucose ((2)H-G) during fasting (n = 6) and during physiologic (1.0 mU.kg(-1).min(-1), n = 4) and supraphysiologic (5.0 mU.kg(-1).min(-1), n = 4) euglycemic hyperinsulinemia. Arterial plasma was sampled for 180 min to quantify the parameters for the 2 tracers. RESULTS: Fasting Rd((2))(H-G) and Rd(FDG) were 12.3 +/- 2.1 and 13.3 +/- 1.3 micromol.kg(-1).min(-1) (difference not statistically significant [NS]). M values were more than doubled between the 2 clamp studies (P < 0.0001). Rd((2))(H-G) and Rd(FDG) were dose-dependently higher during the hyperinsulinemic state (19.8 +/- 3.7 vs. 18.9 +/- 1.1 and 31.4 +/- 4.1 vs. 31.9 +/- 2.3 in 1.0 and 5.0 mU.kg(-1).min(-1) studies, respectively; difference between tracers NS) than during the fasting state, with a parallel suppression of EGP((2))(H-G) and EGP(FDG). Parameters estimated by (18)F-FDG and (2)H-G were equivalent in all groups; their agreement was confirmed by Bland-Altman examination. Total Rd(FDG) correlated with Rd((2))(H-G) (r = 0.74; P = 0.003), M (r = 0.92; P = 0.001), MCR((2))(H-G) (r = 0.52; P = 0.037), and EGP((2))(H-G) (r = -0.71; P = 0.004). EGP(FDG) correlated with EGP((2))(H-G) (r = 0.62; P = 0.018), Rd((2))(H-G) (r = -0.78; P = 0.001), and MCR((2))(H-G) (r = -0.67; P = 0.008). The (18)F-FDG mean transit time correlated inversely with the M and Rd values and positively with EGP. CONCLUSION: The glucose analog (18)F-FDG can be used in the simultaneous estimation of whole-body glucose turnover and production and regional (18)F-FDG PET measurements under both fasting and insulin-stimulated conditions.  相似文献   
6.
7.
BACKGROUND AND PURPOSE: Administrative registers, like hospital discharge registers and causes of death registers are used for the monitoring of disease incidences and in the follow-up studies. Obtaining reliable results requires that the diagnoses in these registers are correct and the coverage of the registers is high. The purpose of this study was to evaluate the validity of the Finnish hospital discharge registers and causes of death registers stroke diagnoses against the population-based FINSTROKE register. METHODS: All first stroke events from the hospital discharge registers and causes of death registers from the areas covered by the FINSTROKE register were obtained for years 1993-1998 and linked to the FINSTROKE register. The sensitivity and positive predictive values were calculated. RESULTS: A total of 3633 stroke events, 767 fatal and 2866 non-fatal strokes, were included in the registers. The sensitivity for all first stroke events was 85%, for fatal strokes 86% and for non-fatal strokes 85%. The positive predictive values for all first strokes was 86%, for fatal strokes 92% and for non-fatal strokes 85%. The sensitivity as well as the positive predictive values for subarachnoid haemorrhage and intracerebral haemorrhage was higher than for cerebral infarctions. There were no marked differences in the sensitivity or positive predictive values between men and women. CONCLUSIONS: The sensitivity and the positive predictive values of the Finnish hospital discharge registers and causes of death registers are fairly good. Finnish administrative registers can be used for the monitoring of stroke incidence, but the number of cerebral infarctions should be interpreted with caution.  相似文献   
8.
A solid-phase radioimmunoassay (RIA) has been developed for the detection of human rotavirus-specific IgA, IgG, and IgM antibodies. Nebraska calf diarrhea virus grown in LLC-MK2 cell cultures in the presence of trypsin was directly adsorbed onto polystyrene balls, and antibodies that attached to the virus-coated balls were detected by subsequent binding of 125I-labeled antibodies specific to human alpha, gamma or mu chains of human Iga, IgG, or IgM immunoglobulins. A total of 116 serum specimens from 58 adult patients were tested. Binding ratios between the positive and the negative serum varied between 5 and 15, occasionally being 20 or more in the IgA and IgG assays, but rarely exceeding 3 in the IgM assay. The RIA was found to be more sensitive in detecting antibodies to rotavirus than the complement fixation (CF) test, the RIA titers obtained being 50--100 times as high as the CF titers. The method described offers a possibility of evaluating the immune response to human rotavirus and of detecting recent infection.  相似文献   
9.
Pneumococcal infections, especially pneumococcal pneumonia and pneumococcal bacteraemia are leading causes of morbidity and mortality among the elderly. The emergence of penicillin-resistant pneumococcal strains together with the growing number of old people have emphasised the need for prevention of pneumococcal infections. Prospective cohort studies with pneumonia as the endpoint have so far left open the question of the rationale of vaccinating the risk groups with pneumococcal vaccine. Pneumococcal vaccine has been proven effective against pneumococcal bacteraemia, but the incidence of that disease and thus its importance to the individuals themselves and to the healthcare system is small. Adverse events associated with pneumococcal vaccine are quite frequent but, especially in the elderly, mild and do not limit its use. Clinicians should keep the pneumococcal vaccine in mind and discuss its use with their patients at increased risk for pneumococcal infection. However, before pneumococcal vaccine can be included in national vaccination programmes, its cost-effectiveness in preventing invasive infections must be assured or definitive evidence obtained of its effectiveness against non-invasive pneumococcal infection.  相似文献   
10.
Expression of syndecan-1, a cell surface proteoglycan that binds growth factors and extracellular matrix components, was studied in normal and pathological human uterine cervix using immunohistochemical methods. Normal cervical squamous epithelium showed positive staining for syndecan-1 in all cell layers, except the basal cell layer, whereas endocervical columnar epithelium stained weakly. In non-neoplastic reactive lesions, metaplastic squamous cells were positive for syndecan-1, whereas columnar cells showed weak or negative staining. In cervical condylomas, cells showing koilocytotic atypia were positive for syndecan-1. The progression of cervical intraepithelial neoplasia (CIN) grade I to grade III was associated with reduced syndecan-1 expression and localization of syndecan-1 to more superficial cell layers. In squamous cell carcinomas (SCCs), syndecan-1 expression correlated with histological differentiation, being absent from most poorly differentiated tumours. The results suggest that loss of syndecan-1 from atypical cells is an early event during cervical carcinogenesis and show a close association of syndecan-1 expression with preserved epithelial morphology and differentiation.  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