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   4506篇
  免费   217篇
  国内免费   17篇
耳鼻咽喉   50篇
儿科学   127篇
妇产科学   92篇
基础医学   538篇
口腔科学   116篇
临床医学   243篇
内科学   1316篇
皮肤病学   126篇
神经病学   358篇
特种医学   82篇
外科学   621篇
综合类   24篇
一般理论   1篇
预防医学   408篇
眼科学   113篇
药学   312篇
中国医学   27篇
肿瘤学   186篇
  2023年   32篇
  2022年   11篇
  2021年   105篇
  2020年   27篇
  2019年   92篇
  2018年   146篇
  2017年   73篇
  2016年   84篇
  2015年   106篇
  2014年   105篇
  2013年   175篇
  2012年   313篇
  2011年   331篇
  2010年   165篇
  2009年   118篇
  2008年   292篇
  2007年   283篇
  2006年   258篇
  2005年   303篇
  2004年   248篇
  2003年   221篇
  2002年   221篇
  2001年   151篇
  2000年   200篇
  1999年   152篇
  1998年   19篇
  1997年   13篇
  1996年   19篇
  1995年   12篇
  1992年   55篇
  1991年   49篇
  1990年   33篇
  1989年   50篇
  1988年   36篇
  1987年   25篇
  1986年   27篇
  1985年   15篇
  1984年   18篇
  1983年   11篇
  1979年   6篇
  1978年   9篇
  1977年   14篇
  1974年   12篇
  1973年   11篇
  1972年   6篇
  1971年   6篇
  1970年   11篇
  1969年   9篇
  1968年   15篇
  1967年   6篇
排序方式: 共有4740条查询结果,搜索用时 960 毫秒
101.
To determine whether fish have an insulin-like growth factor II/mannose 6-phosphate (IGF-II/M6-P) receptor similar to that of mammals, we have performed binding, cross-linking, and immunoprecipitation experiments with wheat-germ-agglutinin- and mannose 6-phosphate (M6-P)-affinity-purified receptor preparations from fish embryos. In both receptor preparations, IGF-II binding was specific, because labeled IGF-II could only be completely displaced by cold IGF-II but not by IGF-I or insulin. Labeled IGF-II bound to a protein with a molecular mass of approximately 250 kDa, which could be immunoprecipitated with an antibody against the rat IGF-II receptor. IGF-II stimulated tyrosine kinase activity in wheat germ agglutinin preparations and was more potent than insulin or IGF-I, but neither peptide stimulated tyrosine kinase activity in M6-P preparations. Two fish cell lines (CHSE-214 and EPC) were used to confirm the IGF-II binding data obtained in the receptor preparations, revealing the presence of highly specific IGF-II binding and the absence of insulin binding. Furthermore, a decrease of the IGF-I receptors on the cell surface did not alter IGF-II binding in EPC cells. In conclusion, we have detected the presence of IGF-II/M6-P receptors in fish embryos that are similar in structure and specificity for their ligand to those found in mammals.  相似文献   
102.

Purpose

To analyze the influence of adding gentamicin to a regimen consisting of β-lactam or vancomycin plus rifampicin on survival in patients suffering from Staphylococcal prosthetic valve endocarditis (SPVE).

Methods

From January 2008 to September 2016, 334 patients with definite SPVE were attended in the participating hospitals. Ninety-four patients (28.1%) received treatment based on β-lactam or vancomycin plus rifampicin and were included in the study. Variables were analyzed which related to patient survival during admission, including having received treatment with gentamicin.

Results

Seventy-seven (81.9%) were treated with cloxacillin (or vancomycin) plus rifampicin plus gentamicin, and 17 patients (18.1%) received the same regimen without gentamicin. The causative microorganism was Staphylococcus aureus in 40 cases (42.6%) and coagulase-negative staphylococci in 54 cases (57.4%). Overall, 40 patients (42.6%) died during hospital admission, 33 patients (42.9%) in the group receiving gentamicin and 7 patients in the group that did not (41.2%, P = 0.899). Worsening renal function was observed in 42 patients (54.5%) who received gentamicin and in 9 patients (52.9%) who did not (p = 0.904). Heart failure as a complication of endocarditis (OR: 4.58; CI 95%: 1.84–11.42) and not performing surgery when indicated (OR: 2.68; CI 95%: 1.03–6.94) increased mortality. Gentamicin administration remained unrelated to mortality (OR: 1.001; CI 95%: 0.29–3.38) in the multivariable analysis.

Conclusions

The addition of gentamicin to a regimen containing vancomycin or cloxacillin plus rifampicin in SPVE was not associated to better outcome.  相似文献   
103.
104.
Preclinical Research
Krameria cytisoides is used for the treatment of inflammation, stomach pain, and gastric ulcers. The active ingredient from this plant is a peroxide, kramecyne (KACY) which has anti‐inflammatory effects. The aim of the present study was to evaluate the anti‐inflammatory activities of KACY in lipopolysaccharide (LPS)‐induced systemic chronic inflammation in mice for 60 days, using dexamethasone (DEX) as the positive control, vehicle (the LPS group) as the negative control and the control group (mice without inflammation). KACY did not affect survival, body weight or relative organ weight in mice but it: decreased nitric oxide (NO) production by 68%; prostaglandin E2 (PGE2) by 67%; increased release of anti‐inflammatory cytokine IL‐10 (2.0‐fold), and reduced production of the proinflammatory cytokines, IL‐6 (2.0‐fold), IL‐1β (2.4‐fold), and TNF‐α (2.0‐fold). Furthermore, the gastroprotective effects of KACY in mice were evaluated in an ethanol‐induced gastric ulcer model. The results showed that KACY at 50 and 100 mg/kg exerted gastroprotective effects with similar activity to 50 mg/kg ranitidine. In gastric tissues, KACY decreased the level of malondialdehyde (MDA) but increased the catalase (CAT) activity. KACY have potential for the treatment of chronic inflammatory diseases due its similar activity to that of DEX. It also has gastroprotective effects. Drug Dev Res 76 : 185–193, 2015. © 2015 Wiley Periodicals, Inc.  相似文献   
105.

Purpose

To describe total fluid intake (TFI) according to socio-demographic characteristics in children and adolescents worldwide.

Methods

Data of 3611 children (4–9 years) and 8109 adolescents (10–18 years) were retrieved from 13 cross-sectional surveys (47 % males). In three countries, school classes were randomly recruited with stratified cluster sampling design. In the other countries, participants were randomly recruited based on a quota method. TFI (drinking water and beverages of all kinds) was obtained with a fluid-specific record over 7 consecutive days. Adequacy was assessed by comparing TFI to 80 % of adequate intake (AI) for total water intake set by European Food Safety Authority. Data on height, weight and socio-economic level were collected in most countries.

Results

The mean (SD) TFI ranged from [1.32 (0.68)] to [1.35 (0.71)] L/day. Non-adherence to AIs for fluids ranged from 10 % (Uruguay) to >90 % (Belgium). Females were more likely to meet the AIs for fluids than males (4–9 years: 28 %, OR 0.72, p = 0.002; 10–18 years: 20 %, OR 0.80, p = 0.001), while adolescents were less likely to meet the AI than children (OR 1.645, p < 0.001 in males and OR 1.625, p < 0.001 in females).

Conclusions

A high proportion of children and adolescents are at risk of an inadequate fluid intake. This risk is especially high in males and adolescents when compared with females or children categories. This highlights water intake among young populations as an issue of global concern.
  相似文献   
106.
Cardiovascular Drugs and Therapy - Obesity is associated with systemic insulin resistance and cardiac hypertrophy with fibrosis. Peroxisome proliferator-activated receptors (PPARs) regulate...  相似文献   
107.
108.
Zinc is an important element during the prenatal period. Since plasma zinc levels are not directly related to the nutritional status of this metal in pregnant women, we designed this study to find out if plasma protein zinc binding capacity is a more reliable parameter than total serum zinc to establish zinc nutritional status during pregnancy. We analyzed total serum zinc and zinc binding capacity in 84 normal pregnant women and in 14 nonpregnant women. Within pregnant women, samples were classified according to the gestational age. Total zinc serum was significantly decreased in pregnant women as compared to control ones. The decrease in zinc occurred slowly during the whole period of pregnancy; a negative correlation was found between serum zinc and gestational time. Protein zinc binding capacity was found to be significantly higher in pregnant women than in the control ones. This parameter was positively correlated to total serum zinc in pregnancy. We conclude that since the protein zinc binding capacity increases with advancing gestation, pregnant women take advantage of this to maintain the levels of serum-free zinc, transferable to the fetus.  相似文献   
109.
A 43-year-old female with Staphyloccocus-induced perianal abscess, was admitted to hospital because of a clinical picture of acute renal failure and thrombotic microangiopathy. Schistocytes, thrombopenia, a negative Coombs test and no detectable plasma haptoglobin were diagnostic for thrombotic microangiopathy. Antibiotics, surgical drainage, plasmapheresis and fresh frozen plasma were given with a favourable evolution. We review the prognostic factors determining recovery of renal function and hematological abnormalities.  相似文献   
110.
We evaluated the effect of salvage antiretroviral therapy with lopinavir/ritonavir (LPV/r) on the immune system of heavily antiretroviral pretreated HIV-infected children. We carried out a longitudinal study in 20 antiretroviral experienced HIV-infected children to determine the changes in several immunological parameters (T cell subsets, thymic function) every 3 months during 18 months of follow-up on salvage therapy with LPV/r. Statistical analyses were performed with the Wilcoxon test, taking as a reference the basal value at the entry in the study. HIV-infected children showed an increase of CD4+ T cells, a decrease in CD8+ T cells, and an increase in T cell rearrangement excision circle (TRECs) levels. The percentage of HIV children with undetectable viral load (VL < or = 400 copies/ml) increased significantly (p = 0.007) and the percentage with SI viral phenotype decreased significantly (p = 0.002) at the end of the study. Thus, the viral phenotype changed to NSI/R5 after salvage therapy with LPV/r. Interestingly, we observed a significant decrease of memory (CD4+ CD45RO+) and a moderate decrease of activated (CD4+ HLA-DR+, CD4+ HLA-DR+CD38, CD4+, CD45RO+HLA-DR+) CD4+ T cells during the follow-up. On the other hand, memory (CD8+ CD45RO+ and CD8+ CD45RO+CD38+), activated (CD8+ HLA-DR+CD38+, CD8+ HLA-DR+, CD8+ CD38+), and effector (CD8+ CD57+, CD8+ CD28(-)CD57+) CD8+ T cells had a very significant decrease during follow-up. Our data indicate an immune system reconstitution in heavily pretreated HIV-infected children in response to salvage therapy with LPV/r as a consequence of a decrease in immune system activation and an increase in thymic function.  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