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   598篇
  免费   42篇
  国内免费   1篇
耳鼻咽喉   6篇
儿科学   21篇
妇产科学   9篇
基础医学   91篇
口腔科学   3篇
临床医学   55篇
内科学   161篇
皮肤病学   31篇
神经病学   40篇
特种医学   19篇
外科学   61篇
综合类   1篇
一般理论   1篇
预防医学   43篇
眼科学   5篇
药学   43篇
肿瘤学   51篇
  2024年   1篇
  2023年   6篇
  2022年   2篇
  2021年   16篇
  2020年   9篇
  2019年   15篇
  2018年   19篇
  2017年   14篇
  2016年   19篇
  2015年   27篇
  2014年   20篇
  2013年   25篇
  2012年   41篇
  2011年   51篇
  2010年   35篇
  2009年   27篇
  2008年   32篇
  2007年   44篇
  2006年   29篇
  2005年   23篇
  2004年   12篇
  2003年   8篇
  2002年   21篇
  2001年   15篇
  2000年   10篇
  1999年   13篇
  1998年   7篇
  1997年   6篇
  1996年   4篇
  1995年   3篇
  1994年   4篇
  1993年   3篇
  1992年   10篇
  1991年   7篇
  1990年   9篇
  1989年   7篇
  1988年   7篇
  1987年   8篇
  1986年   4篇
  1985年   7篇
  1984年   6篇
  1983年   2篇
  1982年   3篇
  1981年   2篇
  1980年   1篇
  1979年   2篇
  1978年   1篇
  1975年   1篇
  1974年   1篇
  1970年   2篇
排序方式: 共有641条查询结果,搜索用时 187 毫秒
1.
OBJECTIVE: To assess the effects of adding combined estradiol/norethisterone acetate therapy (CENT) to goserelin acetate treatment (GA) of dysfunctional uterine bleeding (DUB) in perimenopausal women. METHODS: In a randomized, placebo-controlled, double-blind trial followed by an open follow-up study, 31 perimenopausal women with DUB were recruited from gynecological outpatient departments of two Dutch hospitals and randomized for treatment with either GA/placebo or GA/CENT for 6 months followed by 18 months of GA/CENT for all. The main outcome measures were abdominal pain, number of bleeding days, double-layer endometrial thickness (DET), Greene climacteric score (GCS), visual analog scale for well-being, bone mineral density (BMD) and mammographic density (BI-RAD score). RESULTS: Abdominal pain, number of bleeding days and DET decreased in both groups, the between-group difference in decrease not being statistically significant. GCS initially showed significant improvement in the GA/CENT group. BMD decreased significantly in the GA/placebo group (-4.1%) compared with the GA/CENT group (-0.3%). Another 18 months of GA/CENT did not result in a lasting difference in BMD between groups. BI-RAD scores did not differ significantly between or within the two groups. CONCLUSIONS: Adding CENT to GA treatment for DUB in perimenopausal women initially prevented BMD loss and improved climacteric complaints, while having no negative impact on vaginal bleeding, abdominal pain or BI-RAD scores. However, prolonged treatment did not result in a lasting prevention of bone loss.  相似文献   
2.
BACKGROUND: Intravenous methylprednisolone pulses (IVMP) are more efficacious and better tolerated than oral prednisone in Graves' ophthalmopathy (GO) patients. However, acute and severe liver damage has been reported in sporadic cases during IVMP, resulting in fatal acute liver failure in four patients so far. The mechanism causing the liver damage is incompletely understood. DESIGN: We performed a prospective observational study in 13 patients with dysthyroid optic neuropathy (group A) and in 14 patients with moderately severe GO (group B) who were treated with high-dose (group A) or low-dose (group B) IVMP; cumulative steroid doses were 8.45 g in group A and 4.5 g in group B, and follow-up time was 24 weeks. MAIN OUTCOME: Slight increases in serum aminotransferases (in alanine aminotransferase [ALAT] more than in aspartate aminotransferase [ASAT]) were observed, in seven patients exceeding the upper normal limit of 40 U/L. These changes were more prominent in group A than in group B as was also evident from a decrease in ASAT/ALAT ratio in group A but not in group B. Changes in serum aminotransferases occurred especially in the first 6 weeks of IVMP, becoming smaller thereafter with the decrease in steroid dosage. Pretreatment liver steatosis or diabetes were not related to liver damage, but preexistent viral hepatitis was. CONCLUSION: IVMP in GO patients causes dose-dependent liver damage by a direct toxic effect of glucocorticoids on hepatocytes. Nevertheless, IVMP seems to be pretty safe if cumulative doses exceeding 8 g are avoided and liver function is checked before and at regular intervals during pulse therapy.  相似文献   
3.
The Health Council of the Netherlands published a report in which the best procedure and method for recommending health‐based occupational exposure limits (OELs) for inhaled allergens were identified by evaluating the scientific state of the art. Many respiratory disorders in the workplace arise from inhalation of substances which can cause allergy. To protect workers against respiratory allergy, various preventive measures are taken, one of them being reduction of exposure by setting legally binding standards. These are based on health‐based OELs that specify a level of exposure to an airborne substance, a threshold level, below which it may reasonably be expected that there is no risk of adverse health effects. The Council is of the opinion that an OEL should prevent against allergic sensitization, as sensitization plays a crucial biological role and is a prerequisite for the development of allergy. Furthermore, the Council considers it most likely that the exposure level below which no allergic sensitization develops for most allergens is so low, that OELs are difficult to set with the current knowledge and technical feasibilities. An alternative approach is to accept exposure, which carries a small predefined risk in developing allergic sensitization. In addition, it is worth considering periodic screening of exposed workers on allergic sensitization, because timely intervention can prevent worse. The feasibility of periodic screening and what else is needed to comply with the most important criteria, should however be judged case‐by‐case.  相似文献   
4.
BACKGROUND: No adequate enteral sensitization models are available to study food allergy and the allergenicity of food proteins. To further validate an enteral brown Norway (BN) rat sensitization model under development, we studied specific protein recognition to determine whether a comparable pattern of proteins is recognized by the rat immune system and the human immune system. METHODS: The animals were exposed to either ovalbumin as a positive reference control, hen's egg-white-protein extract, or a cow's milk preparation by daily gavage dosing (0.5, 1, 2.5, 5, 10, or 15 mg protein per rat/day) for 9 weeks. No adjuvants were used during the sensitization studies. The specificities of antibodies against hen's egg-white proteins or cow's-milk proteins in sera from orally sensitized rats and food-allergic patients were studied and compared by immunoblotting. RESULTS: The IgG and IgE antibodies to hen's egg-white proteins and cow's-milk proteins present in sera from orally sensitized rats and food-allergic patients showed a comparable pattern of protein recognition. CONCLUSIONS: Upon daily intragastric exposure to food allergens, the specificities of the induced antibody responses in the BN rat resemble those found in food-allergic patients. These studies add further support to the hypothesis that the BN rat may provide a suitable animal model for food allergy research and research on the allergenicity of food proteins.  相似文献   
5.
6.
7.
BackgroundTransplantation of living allogeneic bone segments may permit reconstruction of large defects, particularly if viability is maintained without immunosuppression. Development of a new autogenous osseous blood supply accomplishes this goal in rodent experimental models. This study evaluates potential systemic and local inflammatory responses to this angiogenesis in a large-animal model.MethodsVascularized allogeneic tibia segments were transplanted orthotopically into matched tibial defects in Yucatan minipigs. Microvascular anastomoses of bone nutrient artery and vein were supplemented by intramedullary placement of an autogenous arteriovenous (AV) bundle in group 1. Group 2 served as a no-angiogenesis control. A 3-drug immunosuppression regimen was withdrawn after 2 weeks. During the 20-week survival period, periodic leukocyte counts and inflammatory cytokine levels were measured. Thereafter, osteocyte survival was quantified and transplant rejection graded by histologic examination and quantitative real-time polymerase chain reaction of immunologic markers.ResultsBoth groups developed an initial systemic response, which resolved after 4 to 6 weeks. No differences were seen in blood cytokine levels. Interleukin 2 expression was diminished in group 1 tibiae. As expected, nutrient pedicles had thrombosed without sustained immunosuppression, occluded by intimal hyperplasia. In group 1, angiogenesis from the autogenous AV bundle resulted in significantly less osteonecrosis (P = .04) and fibrosis (P = .02) than group 2 allotransplants.ConclusionsSystemic immune responses to large-bone allotransplants were not increased by generation of an autogenous osseous blood supply within porcine tibial bone allotransplants. Implanted AV bundles diminished inflammation and fibrosis and improved bone viability when compared to no-angiogenesis controls.  相似文献   
8.
BACKGROUND: We systematically reviewed all available data in the literature to determine the overall eradication rates of currently advised Helicobacter pylori eradication regimens and to resolve conflicting evidence on the impact of antimicrobial resistance on the eradication rates. METHODS: A comprehensive search of all published trials on H. pylori eradication therapy was carried out via an electronic database search, hand-searching and checking reference lists of pharmaceutical companies and other reviews. Full papers and abstracts in the English language which study currently advised eradication regimes were included. RESULTS: 770 study-arms were analysed. Mean eradication rates for bismuth based triple, proton pump inhibitor triple, quadruple and ranitidine bismuth citrate combination therapies vary from 65 to 92%. In case of nitroimidazole resistance, a drop in efficacy of up to 50% was found for bismuth-based triple and proton pump inhibitor-based triple therapies. For quadruple therapy, a significant difference in efficacy was found in the equal-effects analysis; however, this could not be confirmed in the random-effects analysis. In case of clarithromycin resistance, a mean drop in efficacy of 56% was found for one- and two-week clarithromycin containing proton pump inhibitor-triple therapies and of 58% for two-week ranitidine bismuth citrate combined with clarithromycin therapies. For ranitidine bismuth citrate combined with clarithromycin and nitroimidazole, no difference in efficacy was found in case of nitroimidazole or clarithromycin resistance, but data are still scarce. CONCLUSIONS: The cure rate with most regimens dropped significantly, in case of nitroimidazole-resistant strains, compared to nitroimidazole-susceptible strains. In case of clarithromycin resistance, the efficacy of most regimens is also decreased; however, data are still scarce. These data should allow physicians to make a better choice of an appropriate therapy for their patients.  相似文献   
9.
Ninety urine samples were examined twice by 3 "observers" (two persons, using only visual observation, and one person using a spectrophotometric analyser) using multiple reagent teststrips. To determine reproducibility, inter- and intra-observer agreement were calculated and expressed as Cohen's kappa and as weighted kappa. The results show negligible intra-observer differences between the visual and spectrophotometric observation. The lack of agreement between inter- and intra-observer urinalysis results, using multiple reagent test strips was disappointing, considering the simplicity of the test procedure. Further improvement of reproducibility, e.g. by enhancing the discoloration of the test pads, is necessary. Reproducibility is not improved by using a spectrophotometric analyser instead of visual reading of the test strips.  相似文献   
10.
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