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   11410篇
  免费   647篇
  国内免费   82篇
耳鼻咽喉   82篇
儿科学   286篇
妇产科学   179篇
基础医学   1131篇
口腔科学   154篇
临床医学   1217篇
内科学   2886篇
皮肤病学   177篇
神经病学   749篇
特种医学   297篇
外国民族医学   1篇
外科学   2099篇
综合类   290篇
现状与发展   1篇
一般理论   6篇
预防医学   641篇
眼科学   241篇
药学   963篇
中国医学   160篇
肿瘤学   579篇
  2024年   19篇
  2023年   186篇
  2022年   571篇
  2021年   741篇
  2020年   450篇
  2019年   573篇
  2018年   580篇
  2017年   356篇
  2016年   397篇
  2015年   437篇
  2014年   547篇
  2013年   649篇
  2012年   993篇
  2011年   947篇
  2010年   457篇
  2009年   435篇
  2008年   648篇
  2007年   634篇
  2006年   538篇
  2005年   535篇
  2004年   416篇
  2003年   407篇
  2002年   243篇
  2001年   59篇
  2000年   41篇
  1999年   35篇
  1998年   36篇
  1997年   17篇
  1996年   16篇
  1995年   12篇
  1994年   12篇
  1993年   15篇
  1992年   13篇
  1991年   9篇
  1990年   6篇
  1989年   8篇
  1988年   10篇
  1987年   5篇
  1985年   8篇
  1984年   8篇
  1983年   5篇
  1982年   7篇
  1981年   15篇
  1980年   7篇
  1979年   5篇
  1978年   6篇
  1977年   3篇
  1976年   4篇
  1975年   3篇
  1972年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Fludarabine is an active agent in low-grade non-Hodgkin’s lymphoma and chronic lymphocytic leukemia. Paclitaxel is also active in patients with refractory lymphoma, and preclinical data suggest an additive effect with fludarabine in vitro. We performed a phase I trial of fludarabine (25 mg/m2 d 1–3) plus a 3-h infusion of paclitaxel (125, 150, or 175 mg/m2) on d 3 every 28 d in 13 patients with non-Hodgkin’s lymphoma. The paclitaxel dose was escalated in cohorts of 3–4 patients using standard phase I design schema. Dose-limiting toxicity was defined as febrile neutropenia, platelet nadir less than 50,000/μL, or grade 3–4 nonhematologic toxicity. Thirteen patients were accrued to the study, 8 of these 13 patients (62%) had received prior chemotherapy. At the 125-, 150-, and 175-mg/m2 dose levels of paclitaxel, dose-limiting toxicity occurred in 1/4, 0/4, and 0/4 patients, respectively. The single patient with dose-limiting toxicity had febrile neutropenia. Partial response occurred in two of eight patients with low-grade lymphoma and none of five patients with other types of lymphoma. A paclitaxel dose of 175 mg/m2 given as a 3-h infusion on d 3 in conjunction with fludarabine (25 mg/m2 d 1–3 every 4 wk) is a well-tolerated regimen for non-Hodgkin’s lymphoma. Further study will be required in order to determine whether the fludarabine-paclitaxel is more active than fludarabine alone in patients with low-grade lymphoma and chronic lymphocytic leukemia.  相似文献   
62.
63.
AIM OF THE STUDY: The present study was aimed at documentation of botanical anthelmintics used in the traditional veterinary practices in Sahiwal district of Punjab, Pakistan. MATERIALS AND METHODS: In rapid rural appraisal, 331 traditional veterinary healers (TVH) were identified as key respondents in the study area followed by participatory rural appraisal for data collection using a well-structured questionnaire. Information was collected through interviews, focused group discussions and field visits over a period of 2 years. RESULTS: A total of 49 traditional recipes, with 41 plant species representing 39 genera and 27 families, were recorded for the treatment of helminthosis in animals. Most frequently used plants (>/=5 times) were Brassica campestris L. and Mallotus philippinensis (Lam.) Muell.-Arg. and most frequently used families (>/=5 times) were Brassicaceae, Euphorbiaceae and Solanaceae. Most frequently used part of the plant was leaves (n=10) followed in order by seeds (n=9), whole fruit (n=5), aerial parts and whole plant (n=4), fruit (n=3), bulb (n=2) and bark, rhizome, stem, stem plus root and twigs (n=1). Five recipes out of 49 (10.2%) contained more than one plant species and rest 44 (89.8%) contained single plant species. CONCLUSIONS: Twenty out of 41 plants (48.78%) are reported for the first time for their traditional use as anthelmintics in Pakistan. Further studies on pharmacokinetics using scientific procedures may prove these plants as promising candidates for their future use as anthelmintics.  相似文献   
64.
Objective To evaluate the rate and characteristics of postoperative intrauterine adhesions (IUA) that might be formed following hysteroscopic reproductive surgery from both a gross and a histologic perspective as determined by early and late follow-up diagnostic hysteroscopy. Methods Retrospective analysis of 61 women wishing a pregnancy and suffering from a significant intrauterine pathology affecting their reproductive outcome were reviewed. All patients were treated hysteroscopically. Subsequently, they were randomly assigned to perform a follow-up diagnostic hysteroscopy at a variable intervals from their initial surgery. Multiple hysteroscopic-guided biopsies from IUA, when present, were obtained in several cases. Twenty patients were in the early group and had follow-up hysteroscopy performed 2–4 weeks after the initial operation. The late diagnostic group consisted of 41 patients with follow-up hysteroscopy at about 12 months (8–16 months). The two groups were similar to composition. Postoperatively, none of the early diagnostic group underwent hysterosalpingography (HSG) whereas all of the late group performed HSG 4 months following the initial surgery, which showed at least one-third of the cavity free of adhesions. When adhesions were present, no effort was made to lyse them. Results At follow-up hysteroscopy, 25% of both groups had no significant adhesions. Grade I adhesions (thin, filmy) occurred in 60% of the early hysteroscopy patients and in only 12% of the late group (P < 0.05). Grade II adhesions were present in 10% of the early group and in up to 41% in the late group (P < 0.05), whereas Grade III adhesions were present in only 5% of the early hysteroscopy group, but in 22% of the late one (P < 0.05). Correlation between hysteroscopic and histologic findings were good in most of cases in both groups. Follow-up to determine the subsequent reproductive outcome revealed similar conception rates in both groups. Conclusion The IUA that might be formed immediately following hysteroscopic reproductive surgery are histologically different from those appearing a longer time after the original operation. Routine early follow-up hysteroscopy can influence the prognosis resulting from the original surgery.  相似文献   
65.

Objective

We sought to determine whether meconium-stained amniotic fluid is based on chronic hypoxia or not? In case of chronic hypoxia, higher red blood cell (Rbc) count and/or total hemoglobin levels (Hgb) and/or higher fetal hemoglobin (HbF) and/or lower adult hemoglobin (HbA) levels were expected when compared with controls.

Design

Case–control study.

Setting

Obstetric unit of a tertiary ministry of health hospital.

Sample

Fifty singleton pregnancies with meconium-stained amniotic fluid and 50 singleton pregnancies with clear amniotic fluid at all stages of labor.

Methods

Umbilical cord blood samples were collected for determination of total blood parameters and hemoglobin electrophoresis.

Main outcome measures

Red blood cell count, total hemoglobin, fetal and adult hemoglobin contents (HbF and HbA).

Results

Red blood cell count, total hemoglobin, fetal hemoglobin (HbF) and adult hemoglobin (HbA) contents were not different between meconium stained and clear amniotic fluid groups.

Conclusion

These results suggest that meconium passage may not be associated with chronic fetal hypoxia as demonstrated by similar red blood cell count, total hemoglobin values and fetal hemoglobin (HbF) and adult hemoglobin (HbA) contents.
  相似文献   
66.
AIM: To compare the success, clinical outcomes, and maternal and neonatal complications between the Kiwi Omnicup and the Malmstrom metal cup in vacuum assisted delivery. METHODS: This was a prospective randomized comparative trial. Women who required vacuum assisted vaginal delivery were randomized into the Kiwi Omnicup (KO) group and the Malmstrom metal cup (MM) group. The vacuum assisted deliveries were conducted according to hospital protocol. Details of the procedure and delivery outcomes including success and complications were analyzed. RESULTS: One hundred and sixty-four women were recruited - 85 were assigned to vacuum assisted delivery using the KO and 79 the MM. One hundred percent delivery success was achieved with no significant differences between the two instruments in terms of maternal morbidity (P = 0.66). Six women in the MM group sustained post delivery complications in comparison to five in the KO group. Three babies were diagnosed with birth asphyxia in each group. More babies in the MM group were admitted to the Neonatal Intensive Care Unit (NICU) (10 babies versus 5 babies) and suffered complications (14 versus 12 babies), compared to the KO group, although the difference was not statistically significant. There were no intrapartum or neonatal deaths and of those admitted to the NICU, all were discharged within a week without any serious consequences. CONCLUSION: Kiwi Omnicup is an effective alternative to the currently available Malmstrom metal cup for vacuum assisted delivery with no increase in maternal or neonatal morbidity or mortality.  相似文献   
67.
BACKGROUND: Different ovulation trigger methods such as gonadotropin releasing hormone-agonist (GnRH-a) and recombinant human chorionic gonadotropin (r-hCG) plus rescue oocyte retrieval might reveal oocytes in patients with recurrent empty follicle syndrome. CASE: Endogenous luteinizing hormone was triggered with a GnRH-a (Buserelin [Suprefact pro-injection, Aventis-Pharma, Turkey], 250 microg subcutaneously) in a GnRH antagonist (Cetrorelix [Cetrotide 0.25, SeronoTurkey], 0.25 mg/d, starting on day 6), down-regulated cycle. At the first scheduled retrieval, 3 cumulus-oocytecorona complexes were recovered from the left ovary. During chemical denudation with hyaluronidase, 2 of them underwent lysis. The third was a zona-free, germinalvesicle-stage oocyte after mechanical denudation. Oocyte pickup was stopped, and recombinant human chorionic gonadotropin (hCG) (250 microg subcutaneously) was injected. Five cumulus-oocyte-corona complexes were retrieved from the right ovary 24 hours after rescue with recombinant hCG. Only mechanical denudation was done, and 4 zona-free oocytes with germinal vesicle breakdown were seen. All oocytes underwent intracytoplasmic sperm injection, and none of them were fertilized. CONCLUSION: Oocyte maturation defects should be included in etiologic mechanisms for counseling patients with empty follicle syndrome.  相似文献   
68.
目的:研究槟榔子(Areca catechu)粗提取物中所含的抗血小板聚集及抑制乙酰胆碱酯酶活性的有效成分及其作用机制。方法:使用70%甲醇水溶液对槟榔子进行粗提取。使用生物发光血小板凝集仪在富血小板血浆中测定槟榔子粗提取物的抗血小板聚集作用,使用分光光度计在试管内测定槟榔子粗提取物对乙酰胆碱酯酶活性的抑制作用。检测槟榔子中的多种化合物以测定槟榔子中抗血小板聚集及抑制乙酰胆碱酯酶活性的有效成分。结果:槟榔子粗提取物能够抑制花生四烯酸、二磷酸腺苷、血小板活化因子、肾上腺素及钙离子载体引起的血小板聚集,尤其对二磷酸腺苷及钙离子载体引起的血小板聚集的抑制最为明显;槟榔子粗提取物能够显著抑制乙酰胆碱酯酶的活性。在所检测的槟榔子所含化合物中,只有儿茶素对肾上腺素引起的血小板聚集有显著的抑制作用,而这种抑制作用显著弱于槟榔子粗提取物,提示槟榔子中的其他成分参与了这种抑制作用;鞣酸、没食子酸、薯蓣皂苷元和异去甲槟榔次碱能够抑制乙酰胆碱酯酶的活性,其中鞣酸的抑制作用强于槟榔子粗提取物。结论:槟榔子中含有抗血小板聚集及抑制乙酰胆碱酯酶活性的有效成分,而发挥这些功效的确切成分有待进一步的研究证实。  相似文献   
69.
This study aimed to evaluate the effects of carbon nanofibers (CNFs) on the performance of liquid epoxidized natural rubber (LENR)-modified asphalt. The physical, adhesion and rheological properties were determined by several tests such as penetration, elastic recovery, ring and ball softening point, Brookfield rotational viscometer, AFM and dynamic shear rheometer. LENR was used at concentrations of 3, 6, and 9%, while CNFs were used at contents of 0.3, 0.4, and 0.5% by weight of asphalt. Conventional test results showed that the increases in LENR and LENR/CNFs composite contents in binder leads to an increase in the hardness and consistency and a reduction in the temperature susceptibility of base asphalt. Adhesion results revealed that the addition of CNFs significantly increases the adhesion and bonding properties of base and rubberized binders. Rheological properties analysis exhibited that LENR improved the viscoelastic properties and permanent deformation resistance of asphalt at different temperatures and frequencies. On the other hand, it was found that the addition of CNFs significantly improves the stiffness, elasticity, and hardness of LENR-modified binders. The 6% LENR and 0.4% CNFs were found to be the optimum to enhance the physical, adhesion, and rheological properties of asphalt in this study. Thus, it can be stated that the addition of CNFs is promising to improve the performance of rubberized binders for high temperature applications.  相似文献   
70.
Background:Influenza has been shown to exacerbate heart failure (HF). Importantly, no study to date has examined the relationship between HF hospitalizations (HFH) with laboratory confirmed influenza infections. This study evaluated the association between laboratory confirmed influenza infection and HFH in the two largest hospitals in Saskatchewan, Canada.Methods:We used a retrospective self-controlled case series design to evaluate the association between laboratory-confirmed influenza infection and HFH. We compared the incidence ratio for HFH during the influenza risk interval with the control interval. We defined the influenza risk interval as the seven days after a laboratory confirmed influenza result and the control interval as one year before and after the risk interval.Results:We identified 114 HFH that occurred within one year before and after a positive test result for influenza between April 1, 2010, and April 30, 2018. Of these, 28 (28 admissions per week) occurred during the risk interval and 86 (0.853 admissions per week) occurred during the control interval. The incidence ratio of a HFH during the risk interval as compared with the control interval was 33.53 (95% confidence interval [CI], 21.89 to 51.36). A decline in incidence was observed after day seven; between days 8 to 14 and 14 to 28 incidence ratios was 0.91 (95% CI, 0.13 to 6.52) and 0.91 (95% CI, 0.22 to 3.68) respectively.Conclusion:We have observed a significant association between acute influenza infection and HFH. However, further research with a larger sample size and involving a multicenter setting is warranted.Highlights
  • Influenza may contribute and exacerbate heart failure events especially during annual influenza season.
  • Early identification of influenza among patients with heart failure, could lead to earlier treatment with antiviral medication, reduce unnecessary antibiotic use, and tail off the morbidity and mortality.
  • In this study, despite our efficient study design, our sample size was limited to only the two largest hospitals in the province, possibly excluding a significant population in remote areas.
  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