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   34970篇
  免费   2084篇
  国内免费   363篇
耳鼻咽喉   556篇
儿科学   492篇
妇产科学   486篇
基础医学   5765篇
口腔科学   965篇
临床医学   2831篇
内科学   6623篇
皮肤病学   1366篇
神经病学   2480篇
特种医学   2419篇
外国民族医学   1篇
外科学   4353篇
综合类   204篇
一般理论   5篇
预防医学   1671篇
眼科学   623篇
药学   3371篇
中国医学   446篇
肿瘤学   2760篇
  2024年   24篇
  2023年   258篇
  2022年   783篇
  2021年   1251篇
  2020年   573篇
  2019年   805篇
  2018年   1017篇
  2017年   844篇
  2016年   1195篇
  2015年   1588篇
  2014年   1878篇
  2013年   2167篇
  2012年   3122篇
  2011年   3046篇
  2010年   1800篇
  2009年   1603篇
  2008年   2121篇
  2007年   1936篇
  2006年   1733篇
  2005年   1584篇
  2004年   1231篇
  2003年   1067篇
  2002年   915篇
  2001年   802篇
  2000年   729篇
  1999年   535篇
  1998年   302篇
  1997年   215篇
  1996年   211篇
  1995年   141篇
  1994年   164篇
  1993年   113篇
  1992年   159篇
  1991年   174篇
  1990年   184篇
  1989年   164篇
  1988年   148篇
  1987年   138篇
  1986年   119篇
  1985年   88篇
  1984年   55篇
  1983年   47篇
  1982年   48篇
  1981年   51篇
  1980年   29篇
  1979年   28篇
  1978年   28篇
  1977年   32篇
  1975年   27篇
  1970年   23篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
OBJECTIVE: Recent findings have demonstrated that the EEG possesses long-range temporal (auto-) correlations (LRTC) in the dynamics of broad band oscillations. The analysis of LRTC provides a quantitative index of statistical dependencies in oscillations on different time scales. We analyzed LRTC in resting EEG signals in depressed outpatients and healthy controls. METHODS: The participants in this study were 11 non-depressed, age-matched controls, and 11 unmedicated unipolar depressed patients. EEG data were obtained from each participant during 5-min resting baseline periods with eyes closed and then analyzed with detrended fluctuation analysis (DFA), a scaling analysis method that quantifies a simple parameter to represent the correlation properties of a time series. The scaling exponent, the result of DFA, provides a quantitative measure of LRTC from the EEG. RESULTS: The present study demonstrates that all the scaling exponents in depressed patients and healthy controls were greater than 0.5 and less than 1.0, regardless of condition. Furthermore, the scaling exponents of depressed patients have relatively higher values in whole brain regions compared to healthy controls, with significant differences at F3, C3, T3, T4 and O1 channels (p<0.05). Finally, a significant linear correlation was observed between the severity of depression and the scaling exponent over most of the channels, except O2. CONCLUSIONS: These results suggest that the brain affected by a major depressive disorder shows slower decay of the LRTC, and that the persistence of the LRTC of EEG in depressed patients was associated with the severity of depression over most of the cortical areas. SIGNIFICANCE: The DFA method may broaden our understanding of the psychophysiological basis of depression.  相似文献   
52.
53.
Concentrations of metabolites and immunoreactive insulin (IRI) and activities of enzymes related to energy metabolism were measured in plasma of Korean and Japanese beef cattle, which were raised by the indoor feeding system programmed to feed larger amount of roughage in their growing periods and larger amount of concentrate diet in their finishing periods (Japanese feeding system), and grazing New Zealand beef cattle. By the Japanese beef grading system, Korean and Japanese beef cattle showed high beef quality score, average grade 3.3 and 3.6, respectively. The plasma free fatty acid and lactate concentrations and lactate dehydrogenase (LDH), malate dehydrogenase (MDH) and aspartate aminotransferase (AST) activities in Korean beef cattle were significantly higher than those in Japanese beef cattle. The plasma lactate concentration in Korean beef cattle was 8.40 mmol/l, which was similar to the values observed in lactic acidosis. The higher activities of plasma LDH, MDH and AST may indicate slight liver damage by slightly acidotic conditions in Korean beef cattle. New Zealand beef cattle fed on pasture which they harvest by grazing showed significantly lower plasma glucose, cholesterol, lactate and IRI concentrations and enzyme activities than those in Korean and Japanese beef cattle fed on larger amount of concentrate diets. Plasma metabolite concentrations and energy metabolism‐related enzyme activities may be good indicators for evaluating metabolic conditions of beef cattle raised by different feeding systems.  相似文献   
54.
55.
56.
We report here our 10-year experience of a biopsy performed at day 14 after transplantation in 304 patients with stable graft function. The factors that may have influenced subclinical rejection were analyzed according to histology. The incidence of subclinical rejection was 13.2%. Addition of mycophenolate mofetile (MMF) as a primary immunosuppressant significantly decreased the incidence of subclinical rejection compared with patients without such treatment (odds ratio, 0.23; p < 0.05). On the other hand, HLA-DR antigen mismatch (odds ratio, 2.39) and unrelated donor (odds ratio, 2.10) were also significantly associated with decreased subclinical rejection (p < 0.05). The incidence of acute rejection in patients with normal findings was lower than in those with borderline changes or subclinical rejection (0.23 +/- 0.05 vs. 0.48 +/- 0.07 and 0.60 +/- 0.11, respectively; p < 0.05). The graft survival rates in patients with subclinical rejection were lower than in patients with normal or borderline changes at 1 (88.4% vs. 97.9% and 99.1%; p < 0.05), 5 (77.8% vs. 96.2% and 95.9%; p < 0.05) and 10 (62.3% vs. 96.2% and 93.7%; p < 0.05) years. Thus, a protocol biopsy performed on day 14 after transplantation is useful for predicting graft survival. Triple therapy including MMF, related donor and HLA-DR antigen match are important factors for reducing subclinical rejection in living-donor renal transplantation.  相似文献   
57.
OBJECTIVE: Although cutaneous leishmaniasis (CL) occurs mostly in the facial area, periocular involvement accounts for 2-5% of the facial lesions. CL lesions localized in the periocular region can easily be confused with various other diseases. The aim of this study was to examine the frequency of periocular involvement in CL in the Cukurova region of Turkey, as well as the clinical characteristics, diagnosis and methods of treatment of this disease. METHODS: Between December 1998 and December 2004, patients who were diagnosed with CL were evaluated prospectively with respect to periocular involvement. RESULTS: From the 2066 patients evaluated with CL, 2622 lesions were identified. In 59 (2.9%) of these patients, a total of 66 (2.5%) lesions were located in the periocular area. Thirty-two (48.5%) of these lesions were of the papular type, 15 (22.7%) the nodulo-ulcerative type, 10 (15.2%) the plaque type, and nine (13.6%) the nodular type. Dacryocystitis was identified in four patients with periocular involvement. Over the follow-up period, no ocular or periocular deformities or complications developed in these patients. CONCLUSION: Patients suspected of CL should be evaluated and treated early in the course of their disease to prevent any permanent ocular or periocular deformities.  相似文献   
58.
The Stiles-Crawford effect of the first kind (SCE-I) was measured on both emmetropic and myopic subjects at six different retinal locations. The results revealed a number of significant discrepancies in receptor alignment between the groups of different refractive errors. In myopic subjects, the receptors in the nasal retina (i.e. between the fovea and the optic nerve head) were found to be aligned nasally towards the optic nerve head, whereas the receptors in the temporal retina were aligned towards the centre of the exit pupil. In emmetropic subjects, the receptors across the retina were finely tuned towards the centre of the exit pupil. The magnitude of the receptor displacement in myopic subjects was found to be directly associated with the length of the eyeball.  相似文献   
59.
OBJECTIVE: Behavioral disturbances in dementia are extremely prominent and distressful, and often result in serious physical, social, and economic consequences. The authors compared the efficacy and tolerability of risperidone and haloperidol in the treatment of behavioral and psychological symptoms of dementia (BPSD) in institutionalized elderly Korean patients with Alzheimer disease, vascular dementia, or mixed dementia. METHODS: This was an 18-week double-blind, crossover study involving 120 patients who were randomly assigned to receive flexible doses (0.5-1.5 mg/day) of risperidone or haloperidol. BPSD were assessed using the Korean version of the Behavioral Pathology in Alzheimer's Disease Rating Scale (BEHAVE-AD-K), the Korean version of the Cohen-Mansfield Agitation Inventory (CMAI-K), and the Clinical Global Impression of Change scale (CGI-C). Safety and tolerability assessments included the Extrapyramidal Symptom Rating Scale and the incidence of adverse events. RESULTS: Both risperidone and haloperidol were efficacious in alleviating BPSD. However, when receiving risperidone, patients showed significantly greater improvement than when receiving haloperidol in the total and subscale scores of the BEHAVE-AD-K, the total and subscale scores of the CMAI-K, and the scores on the CGI-C scale. Also, risperidone had an additional benefit on aggressiveness and anxieties/phobias. The risk of antipsychotic-induced parkinsonism throughout this study was significantly lower with risperidone than with haloperidol. CONCLUSION: Risperidone had a favorable efficacy and tolerability profile compared with haloperidol in the treatment of BPSD in this patient population.  相似文献   
60.
BACKGROUND: IgE-mediated carboplatin hypersensitivity reactions occur in up to 30% of patients receiving this agent for chemotherapy of solid tumors, thus limiting therapeutic options. OBJECTIVE: To describe our experience with intravenous carboplatin desensitization regimens, which culminated in a standardized, successful protocol for safe administration. METHODS: Eight consecutive patients with ovarian cancer who had experienced severe anaphylactic reactions to carboplatin were referred to our hospital. Intradermal skin testing was performed by raising a 3-mm bleb by injection of undiluted carboplatin at 10 mg/mL, and the wheal size was read at 20 minutes. The outcomes of the various desensitization regimens were documented prospectively, and the experience gained was used to develop a standardized protocol for administration. RESULTS: All patients had positive intradermal skin test results. The first 3 patients were treated with short (90 minutes to 6 hours) desensitization protocols, and all protocols failed on the first or second infusions. These 3 and a subsequent 5 patients were given intravenous carboplatin according to a protocol of gradual dose escalation over a 4-log dose range given during a 4-day period, with subsequent 3-weekly infusions given more rapidly by omitting the most dilute log dose on each occasion. All patients tolerated the longer infusion protocol without event, and all but 1 patient experienced appropriate tumor marker response. CONCLUSIONS: Short carboplatin desensitization protocols (less than 6 hours) have an unacceptable failure rate in patients with carboplatin allergy, but longer infusion times (days) are well tolerated without recurrence of the allergic reaction and with good tumor response. In cases where carboplatin is the optimal therapeutic agent, clinicians should not be deterred by an anaphylactic reaction to it or by failure of shorter desensitization regimens.  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