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   1234篇
  免费   122篇
  国内免费   10篇
耳鼻咽喉   6篇
儿科学   56篇
妇产科学   50篇
基础医学   161篇
口腔科学   102篇
临床医学   136篇
内科学   230篇
皮肤病学   17篇
神经病学   112篇
特种医学   126篇
外科学   132篇
综合类   14篇
一般理论   1篇
预防医学   116篇
眼科学   13篇
药学   61篇
肿瘤学   33篇
  2021年   11篇
  2019年   19篇
  2018年   22篇
  2016年   13篇
  2015年   16篇
  2014年   20篇
  2013年   34篇
  2012年   58篇
  2011年   70篇
  2010年   39篇
  2009年   38篇
  2008年   46篇
  2007年   70篇
  2006年   58篇
  2005年   43篇
  2004年   56篇
  2003年   51篇
  2002年   40篇
  2001年   43篇
  2000年   29篇
  1999年   30篇
  1998年   30篇
  1997年   15篇
  1996年   25篇
  1995年   30篇
  1994年   21篇
  1993年   12篇
  1992年   29篇
  1991年   18篇
  1990年   19篇
  1989年   25篇
  1988年   23篇
  1987年   34篇
  1986年   23篇
  1985年   23篇
  1984年   12篇
  1983年   12篇
  1982年   12篇
  1981年   10篇
  1980年   15篇
  1979年   11篇
  1978年   10篇
  1976年   10篇
  1974年   10篇
  1973年   8篇
  1971年   9篇
  1970年   9篇
  1968年   10篇
  1967年   11篇
  1966年   8篇
排序方式: 共有1366条查询结果,搜索用时 31 毫秒
11.
12.
In co-cultures of either the murine pre-B cell line J13, fetal liver cells, or adult peritoneal or bone marrow cells with ST2 mouse bone marrow stromal cells in the presence of granulocyte/macrophage colony-stimulating factor (GM-CSF), the development of CD5+ macrophages was demonstrated by immunohistochemical staining and flow cytometry. Although CD5+ macrophages were not present in the peritoneal cavities of normal mice, approximately 30% of the peritoneal macrophages in viable motheaten (mev/mev) mice, deficient in SHP-1 protein tyrosine phosphatase, expressed cell surface CD5 and B220, markers for B cells. In the mev/mev mice, GM-CSF level in peritoneal fluid was increased significantly. At 5 days after daily intravenous injection with GM-CSF, many CD5+ macrophages appeared in the peritoneal cavity and in omental milky spots of normal mice but fewer in osteopetrosis (op) mutant mice, deficient in macrophage (M)-CSF. These results indicate that GM-CSF, in combination with M-CSF, induces the development and differentiation of CD5+ macrophages in the peritoneal cavity, particularly in the omental milky spots of mice. In the peritoneal cavity of GM-CSF-treated mice, the percentages of hematopoietic progenitor cells doubly positive for CD5 and CD34 or c-kit and of macrophage precursor cells doubly positive for CD5 and ER-MP58 or ER-MP20 were increased significantly during the development of CD5+ macrophages and CD5 B cells, suggesting that CD5+ macrophages and B cells may share a bipotential progenitor in vivo.  相似文献   
13.
BACKGROUND: 'Hospital At Home' schemes are set to increase in the United Kingdom (UK) in response to the NHS Plan. To date, little detailed work has been done on the acceptability of these schemes to patients and their carers. AIM: To compare Hospital at Home patient and carer satisfaction with hospital care. DESIGN OF STUDY: Pragmatic randomised controlled trial. SETTING: Consecutive patients assessed as suitablefor the Leicester Hospital at Home scheme were randomised to Hospital at Home or one of three acute hospitals in the city. METHOD: Patient satisfaction was assessed two weeks after randomisation, or at discharge if later using a six-item questionnaire. Patients' and carers' views of the services were assessed by semistructured interviews. RESULTS: One hundred and two patients were randomised to Hospital at Home and 97 to hospital. Forty-eight (47%) patients in the Hospital at Home arm and 35 (36%) in the hospital arm completed the satisfaction questionnaire, representing 96% and 85% of those eligible, respectively. Total scores were significantly higher in the Hospital at Home (median = 15) than in the hospital group (median = 12). (P<0.001, Mann-Whitney U-test.) Responses to all six questions favoured Hospital at Home, with all but one of these differences being statistically significant. In the Hospital at Homegroup, 24 patients and 18 of their carers were interviewed; in the hospital group 18 patients and seven of their carers were interviewed. Themes emerging from these interviews were that patients appreciated the more personal care and better communication offered by Hospital at Home and placed great value on staying at home, which was seen to be therapeutic. Patients largely felt safe in Hospital at Home, although some would have felt safer in hospital. Some patients and carers felt that better medical care would have been provided in hospital. Carers felt that the workload imposed by Hospital at Home was no greater than by hospital admission and that the relief from care duties at home would be counterbalanced by the added strain of hospital visiting. CONCLUSIONS: Patient satisfaction was greater with Hospital at Home than with hospital. Reasons included a more personal style of care and a feeling that staying at home was therapeutic. Carers did not feel that Hospital at Home imposed an extra workload.  相似文献   
14.
Guidelines urge general practitioners (GPs) to discuss smoking with patients as frequently as possible. Using data collected before and after consultations, this study confirms that GPs are more likely to discuss smoking in the context of smoking-related problems. Encouraging GPs to make greater use of problem-orientated opportunities to discuss smoking may have more effect on rates of advice giving than urging them to advise all smokers.  相似文献   
15.
Fasting serum lipid levels and changes in plasma glucose, fatty acid non-esterified (Nefa), and blood pyruvate levels during intravenous glucose tolerance tests were measured in 13 normal subjects before and one, five, and 15 days after the administration of 1-triiodothyronine (T3) calculated as 6 mug/kg body weight.Significant increases in the mean basal metabolic rate and the mean fasting plasma Nefa level occurred within 10 to 17 hours of a single dose of T3, while a rise in the mean fasting plasma glucose concentration just failed to achieve significance. Fasting concentrations of blood pyruvate and serum triglyceride were unaffected. A significant fall in serum cholesterol levels was produced and lasted at least five days. All other indices returned to normal by five days.During intravenous glucose tolerance tests performed at intervals after T3 administration no change in plasma glucose levels from control values was seen. Mean plasma Nefa and blood pyruvate levels, however, were significantly raised above control values during the early stages of the test 10 to 17 hours after T3. The relationship between these findings and those observed in clinical thyrotoxicosis is discussed.  相似文献   
16.
Based on the tail-flick response to noxious thermal stimuli, we determined in the present study that effective antinociception could be achieved in adult male Sprague-Dawley rats 15 min after intravenous infusion of propofol at 60 mg/kg/h. Simultaneous power spectral analysis of the electroencephalographic (EEG) and systemic arterial pressure signals further revealed a concomitant depression of the activity of all EEG frequency bands (δ, θ, , β), alongside hypotension, negative inotropic and chronotropic actions, and attenuated baroreceptor reflex and vasomotor activity. These effects were congruent with a plasma concentration of propofol in the arterial blood of 1.70 ± 0.13 μg/ml, as determined by high-performance liquid chromatography.  相似文献   
17.
Maternal serum concentrations of inhibin-A, inhibin-B, activin-A, activin-AB, pro-alphaC-related inhibin forms, total follistatin, steroids and gonadotrophins were measured longitudinally in six normal singleton pregnancies. Maternal venous blood was collected randomly during a spontaneous follicular phase prior to donor insemination, at 5, 7, 9, 11, 16, 20, 24, 28, 32 and 36 weeks after the first missed menses and in the early puerperium. Steroid and gonadotrophin profiles conformed to previous reports. While at week 5 of gestation inhibin-A, activin-A and follistatin concentrations were similar to those at the follicular phase, all three increased progressively (P < 0.001) to maximal concentrations in week 36: approximately 48-fold (3740 +/- 1349 ng inhibin-A/ml), approximately 22-fold (6109 +/- 1443 ng activin-A/ml) and approximately 10-fold (3563 +/- 418 ng follistatin/ml) higher. Pro- alphaC concentrations reached a maximum in weeks 5 (approximately 5- fold, P < 0.001) and 36 (1027 +/- 174 pg/ml, P < 0.01). Inhibin-B (71 +/- 23 pg/ml prior to pregnancy) was undetectable (<12 pg/ml) between week 5-16 of gestation but increased slightly in the third trimester (26 +/- 7 pg/ml in week 36). Activin-AB was undetectable throughout pregnancy. Post-partum concentrations of inhibin-A (41 +/- 12 ng/ml), inhibin-B (<12 pg/ml), activin-A (950 +/- 149 pg/ml), pro-alphaC (128 +/- 22 pg/ml) and follistatin (990 +/- 79 ng/ml) were substantially lower than at week 36 of gestation. The activin-A:follistatin ratio increased from 0.5 in week 5 to 1.8 in week 36, suggesting that more free activin-A is available in the maternal circulation during late pregnancy.   相似文献   
18.
BACKGROUND: If a validated questionnaire, when applied to patients reporting with symptoms of intermittent claudication, could adequately discriminate between those with and without peripheral arterial disease, GPs could avoid the diagnostic measurement of the ankle brachial index. AIM: To investigate the Edinburgh Claudication Questionnaire (ECQ) in general practice and to develop a clinical decision rule based on risk factors to enable GPs to easily assess the likelihood of peripheral arterial disease. DESIGN OF STUDY: An observational study. SETTING: General practice in The Netherlands. METHOD: This observational study included patients of > or =55 years visiting their GP for symptoms suggestive of intermittent claudication or with one risk factor. The ECQ and the ankle brachial index were performed. The prevalence of peripheral arterial disease, defined as an ankle brachial index <0.9, was related to risk factors using logistic regression analyses, on which a clinical decision rule was developed and related to the presence of peripheral arterial disease. RESULTS: Of the 4790 included patients visiting their GP with symptoms suggestive of intermittent claudication, 4527 were eligible for analyses. The prevalence of peripheral arterial disease in this group was 48.3%. The sensitivity of the ECQ was only 56.2%. The prevalence of peripheral arterial disease in a clinical decision rule that included age, male sex, smoking, hypertension, hypercholesterolemia, and a positive ECQ, increased from 14% in the lowest to 76% in the highest category. CONCLUSION: This study indicates that the ECQ alone has an inadequate diagnostic value in detecting patients with peripheral arterial disease. The ankle brachial index should be performed to diagnose peripheral arterial disease in patients with complaints suggestive of intermittent claudication, although our clinical decision rule could help to differentiate between extremely high and lower prevalence of peripheral arterial disease.  相似文献   
19.
To formulate a 'logic' for how a single immunoglobulin variable region gene generates antibodies with different antigen specificity and polyreactivity, we analysed chimeric antibodies produced in transgenic mice carrying the germ-line human V3-23 gene, multiple diversity (D) and joining (J) gene segments. Hybridomas producing antibodies encoded by the V3-23 gene in combination with different mouse Vkappa genes were obtained by fusion of splenocytes from transgenic mice. All antibodies had human mu-chains and mouse light chains, were multimeric in structure and expressed the human V3-23 gene. Nucleotide sequence analyses of genes encoding the heavy and light chains of 12 antibodies in relation to antigen specificity highlighted the importance of heavy chain variable region CDR3 in determining reactivity with different antigens. However, the results also suggest that non-CDR3 sequences intrinsic to the V3-23 gene itself may be involved in, or determine, the binding of the chimeric antibodies to some of the antigens tested in the current study.  相似文献   
20.
The effect of magnesium sulphate in releasing calcium emission from interference by phosphate and sulphate has been investigated.  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