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   199940篇
  免费   15846篇
  国内免费   10831篇
耳鼻咽喉   1813篇
儿科学   2449篇
妇产科学   3908篇
基础医学   23044篇
口腔科学   3411篇
临床医学   25326篇
内科学   32403篇
皮肤病学   2324篇
神经病学   11093篇
特种医学   6924篇
外国民族医学   70篇
外科学   21795篇
综合类   27810篇
现状与发展   34篇
一般理论   35篇
预防医学   12372篇
眼科学   5474篇
药学   19570篇
  197篇
中国医学   9092篇
肿瘤学   17473篇
  2024年   2393篇
  2023年   3779篇
  2022年   7221篇
  2021年   9455篇
  2020年   7290篇
  2019年   6519篇
  2018年   6435篇
  2017年   5692篇
  2016年   5414篇
  2015年   8206篇
  2014年   10145篇
  2013年   9488篇
  2012年   14131篇
  2011年   15420篇
  2010年   9484篇
  2009年   7547篇
  2008年   10276篇
  2007年   10286篇
  2006年   9942篇
  2005年   9857篇
  2004年   6870篇
  2003年   6150篇
  2002年   5229篇
  2001年   4780篇
  2000年   4897篇
  1999年   5093篇
  1998年   2858篇
  1997年   2936篇
  1996年   2258篇
  1995年   2061篇
  1994年   1816篇
  1993年   1197篇
  1992年   1840篇
  1991年   1592篇
  1990年   1319篇
  1989年   1152篇
  1988年   1019篇
  1987年   927篇
  1986年   762篇
  1985年   586篇
  1984年   392篇
  1983年   301篇
  1982年   178篇
  1981年   164篇
  1980年   152篇
  1979年   188篇
  1978年   113篇
  1977年   84篇
  1974年   91篇
  1973年   82篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
本文对经病理证实的24例心脏转移癌进行超声心动图研究分析,总结其声像图特征,提出了超声诊断依据。认为超声心动图是临床及早发现诊断心脏转移癌的重要技术手段。  相似文献   
992.
Shieh B  Chang MJ  Ko WC  Chen EJ  Wu JC  Lee CF  Chang TT  Li C 《Intervirology》2003,46(2):105-113
OBJECTIVE: Since virus infections in AIDS patients are mostly inevitable and as they frequently cause disease deterioration and therapeutic failures, a comprehensive investigation was made of the influence of the coinfections of 9 well-known viruses on disease progression in patients infected with human immunodeficiency virus type 1 (HIV). METHODS: A cross-sectional study of 62 HIV-positive patients was conducted to correlate the prevalence rates for the 9 viruses with the alanine aminotransferase (ALT) levels and CD4 cell counts of the patients. RESULTS: The rates of HIV-positive patients infected with the 9 viruses are significantly higher than those of the control groups. Furthermore, almost one third of the patients in the studied group was coinfected with transfusion-transmitted virus (TTV) and manifested significantly higher ALT levels (p = 0.020), and these were raised further if coinfection with TTV and human hepatitis C virus had occurred (p = 0.010). By analyzing CD4 cell counts, the only significant effect on AIDS progression which could be detected was coinfection with human herpesvirus 8. CONCLUSION: This result confirmed that immune-suppressed persons are more vulnerable to common virus infections. Unlike hepatitis B or C virus, TTV seems to accelerate the progression of chronic hepatitis in HIV-infected patients.  相似文献   
993.
In two clinical trials the mouse antiidiotypic monoclonal antibody (MAb) MF11-30, which bears the internal image of human high-molecular-weight-melanoma-associated antigen (HMW-MAA) was administered by subcutaneous route without adjuvants to patients with stage IV malignant melanoma on day 0, 7, and 28. Additional injections were administered if anti-antiidiotypic antibodies were not found or their titer decreased. In the first phase I trial with 16 patients the initial dose was 0.5 mg per injection and escalated to 4 mg per injection. Neither toxicity nor allergic reactions were observed despite the development of anti-mouse Ig antibodies. Minor responses were observed in three patients. In a second clinical trial MAb MF11-30 was administered to 21 patients at a dose of 2 mg per injection, since this dose had been shown in the initial study to be effective in inducing anti-antiidiotypic antibodies. Two patients were inevaluable; in the remaining 19 patients, the average duration of treatment was 34 wk. In this trial as well, neither toxicity nor allergic reactions were observed. 17 of the 19 immunized patients increased the levels of anti-mouse Ig antibodies and 16 developed antibodies that inhibit the binding of antiidiotypic MAb MF11-30 to the immunizing anti-HMW-MAA MAb 225.28. One patient increased the level of anti-HMW-MAA antibodies. One patient achieved a complete remission with disappearance of multiple abdominal lymph nodes for a duration of 95 wk. Minor responses were observed in three patients. These results suggest that mouse antiidiotypic MAb that bear the internal image of HMW-MAA may be useful reagents to implement active specific immunotherapy in patients with melanoma.  相似文献   
994.
Chang K-H, Lai C-H, Chen S-C, Hsiao W-T, Liou T-H, Lee C-M. Body composition assessment in Taiwanese individuals with poliomyelitis.

Objectives

To measure the changes in the total and regional body fat mass, and assess the clinical usefulness of the body mass index (BMI) in detecting overweight subjects with sequelae of poliomyelitis.

Design

Prospective, cross-sectional study.

Setting

General community.

Participants

Subjects with poliomyelitis (n=17; age range, 42–57y; mean, 47y; 12 men, 5 women) and able-bodied people (n=17) matched by sex, age, body weight, and body height participated in the study.

Interventions

Not applicable.

Main Outcome Measures

Total and regional body composition was measured with dual-energy x-ray absorptiometry. Clinical characteristics such as blood pressure, serum biochemical studies, and habitual behaviors (daily cigarette smoking, alcohol consumption, and exercise regimen) of all participants were evaluated.

Results

Compared with able-bodied controls, subjects with poliomyelitis had a 50% greater total body fat mass, significant increases in the regional fat mass in every part of the body, and had the greatest increase of fat mass in the thorax. Nearly all the subjects (94%) with poliomyelitis were obese according to standards of body composition. However, one third of them had a BMI value of less than 25.0kg/m2.

Conclusions

People with poliomyelitis have a higher prevalence of obesity and a significant increase in total and regional fat mass. Current BMI underestimates the total body fat mass percentage compared with the control; therefore, a population-specific BMI should be used to address the prevalence of obesity in postpolio survivors.  相似文献   
995.
996.
In the human somatosensory system, the contralateral primary somatosensory cortex (SI) is presumed to process and encode type and intensity of the sensory inputs, whereas the bilateral secondary somatosensory cortex (SII) is believed to perform higher order functions including sensorimotor integration, integration of information from the two body halves, attention, learning and memory. In this fMRI study we investigated the effect of attention on the activation of SI and SII, as induced by nonpainful and painful rare deviant electric stimuli during somatosensory oddball tasks. The working hypothesis is of stronger effects of attention on SII with respect to SI. Four runs were acquired according to an oddball scheme. Frequent nonpainful electrical stimuli were delivered to the ulnar nerve at motor threshold, whereas rare/deviant stimuli were delivered to median nerve in four conditions (one condition per run): nonpainful, painful, counting nonpainful, and counting painful. Results showed a statistically significant fMRI activation in bilateral SII but not in contralateral SI when the rare/deviant median nerve stimuli were delivered at nonpainful and painful levels as well as at the two levels of attention considered (i.e., associated with counting and non-counting tasks). Furthermore, fMRI activation in SII did not differ across the different levels of stimulus intensity (nonpainful, painful) and attention (non-counting, counting). These results corroborate the notion that SII is the target of independent pathways for the processing and integration of nonpainful and painful somatosensory stimuli salient for further high-order elaborations.  相似文献   
997.
The presence of anticardiolipin antibodies (ACLA) in multiple sclerosis (MS) patients has been reported, but there are some debates on the relationship between ACLA and MS. We assessed the clinical features of neuromyelitis optica spectrum disorders (NMOSD) patients with ACLA. A consecutive cohort of 480 subjects with NMOSD (n = 70), MS (n = 90) and control (n = 220) were analysed retrospectively. Patients’ serum was tested by a dot-immunogold filtration assay for the presence of ACLA-IgG, IgM and IgA antibodies. In MS patients, 5 (5.6 %) of the 90 patients showed ACLA-IgG reactivity in the serum. In NMOSD patients, 32 (45.7 %) of the 70 patients showed ACLA reactivity in the serum, among which ACLA-IgG seropositivity was 45.7 % (32/70), ACLA-IgG + IgM seropositivity was 8.6 % (6/70), and ACLA-IgG + IgA seropositivity was 4.3 % (3/70). NMOSD patients were higher in ACLA-IgG (p < 0.0001) and ACLA-IgG + IgM (p = 0.006) than the MS patients. NMOSD patients had higher ACLA-IgG than the control patients (p < 0.0001). In comparison with the controls, the MS patients were lower in ACLA for IgG (p = 0.014) and IgM (p = 0.004). Seropositive ACLA patients increased in age (p = 0.013) and had higher D-dimer levels (DD) (p = 0.002) than the seronegative NMOSD patients. Furthermore, positive ACLA-IgG + IgM patients were increased in age (p = 0.001), had higher baseline EDSS (p = 0.001), antithrombin III activity (p = 0.04), and DD levels (p = 0.005) than the pure positive ACLA-IgG NMOSD patients. Patients with NMOSD had more occurrences of ACLA than patients with MS. NMOSD patients with positive ACLA-IgG + IgM had a worse outcome that may be associated with elder age and abnormal coagulation parameters in blood.  相似文献   
998.
OBJECTIVE: To investigate the relations among serum leptin, body mass index (BMI), and various hormone levels in men with spinal cord injury (SCI). DESIGN: Cross-sectional. SETTING: University hospital that is a tertiary referral center. PARTICIPANTS: Forty-seven men with traumatic neurologically complete SCI and 47 age- and BMI-matched male controls. MAIN OUTCOME MEASURES: Baseline levels of various hormones were measured in subjects with SCI. Serum leptin and cortisol levels and BMI were measured in both groups. RESULTS: Serum leptin was significantly higher in the group with SCI than in the control group. A linear relation was found between serum leptin and BMI in both groups separately. A polynomial relation was found between serum leptin level and BMI in the group with SCI. A "J" phenomenon is noted at the lowest BMI. Serum cortisol correlated significantly with serum leptin level in the group with SCI. CONCLUSION: Sympathetic denervation, peripheral nerve palsy, recurrent infections, and possible central neurotransmitter alterations after SCI may contribute to the elevation of serum leptin level in men with SCI.  相似文献   
999.
1000.
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