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   8292篇
  免费   508篇
  国内免费   27篇
耳鼻咽喉   94篇
儿科学   249篇
妇产科学   246篇
基础医学   1360篇
口腔科学   231篇
临床医学   822篇
内科学   1840篇
皮肤病学   207篇
神经病学   799篇
特种医学   178篇
外国民族医学   1篇
外科学   725篇
综合类   53篇
一般理论   5篇
预防医学   728篇
眼科学   116篇
药学   543篇
中国医学   13篇
肿瘤学   617篇
  2023年   67篇
  2022年   156篇
  2021年   298篇
  2020年   172篇
  2019年   245篇
  2018年   249篇
  2017年   211篇
  2016年   238篇
  2015年   245篇
  2014年   282篇
  2013年   414篇
  2012年   670篇
  2011年   624篇
  2010年   364篇
  2009年   306篇
  2008年   560篇
  2007年   571篇
  2006年   516篇
  2005年   552篇
  2004年   430篇
  2003年   398篇
  2002年   347篇
  2001年   71篇
  2000年   64篇
  1999年   59篇
  1998年   55篇
  1997年   48篇
  1996年   49篇
  1995年   44篇
  1994年   33篇
  1993年   36篇
  1992年   37篇
  1991年   45篇
  1990年   39篇
  1989年   29篇
  1988年   21篇
  1987年   17篇
  1986年   18篇
  1985年   26篇
  1984年   18篇
  1983年   23篇
  1982年   14篇
  1981年   14篇
  1980年   16篇
  1979年   10篇
  1977年   10篇
  1975年   9篇
  1974年   11篇
  1972年   9篇
  1970年   10篇
排序方式: 共有8827条查询结果,搜索用时 15 毫秒
71.
72.
Gallium 67 imaging was used in 12 patients with documented Hansen's disease undergoing treatment or not, in an attempt to determine the pattern of the disease. Diagnosis was confirmed by histopathology in all patients. The Mitsuda reaction was seen in all patients. Specific nuclear studies were performed when needed to evaluate particular organs better. Gallium 67 images show homogeneous, diffuse and moderate accumulation over the entire skin surface (except for the face) of untreated patients with multibacillary disease. The facial skin in these cases presented homogeneous, diffuse but very marked uptake of gallium. Internal organ involvement was variable. There was a very good correlation among clinical, scintigraphic, immunological and histopathological data. The pattern of the body skin (skin outlining) and facial skin (beard distribution) may be distinct for untreated patients with multibacillary leprosy.  相似文献   
73.
Central generation of locomotion in the spinal dogfish.   总被引:1,自引:0,他引:1  
After a transection of the spinal cord a dogfish performs continuous swimming movements with a phase lag between adjacent segments. It is shown that the intersegmental coordination remains after an extensive dorsal root transection as well as after curarization. In the former case the motor activity was recorded electromyographically in several segments along the body, in the latter case the intersegmental coordination was evaluated by recording the efferent activity in different ventral roots along the body. It was concluded that a spinal central network can account for the phase lag observed between successive segments during swimming. It was also shown that the efferent activity from parts of the spinal cord with no dorsal roots intact could be influenced by peripheral stimuli such as pressure on the pelvic fins; this result suggests that some afferent fibres reach the spinal cord via the ventral roots.  相似文献   
74.
Perret J 《Revue neurologique》2000,156(5):524-527
  相似文献   
75.
Whether antibodies to human papillomavirus (HPV) capsids, elicited by natural infection, are protective is unknown. This question was addressed in a population-based cohort of 7046 women in Costa Rica by examining the association between baseline seroreactivity to HPV-16, HPV-18, or HPV-31 virus-like particles and the risk of subsequent HPV infection at a follow-up visit 5-7 years after enrollment. Seropositivity to HPV-16, HPV-18, or HPV-31 was not associated with a statistically significant decreased risk of infection with the homologous HPV type [relative risk (RR) and [95% confidence interval (CI)], 0.74 (0.45-1.2), 1.5 (0.83-2.7), and 0.94 (0.48-1.8), respectively]. Seropositivity to HPV-16 or HPV-31 was not associated with a decreased risk of infection with HPV-16 or its genetically related types [RR (95% CI), 0.82 (0.61-1.1) and 0.93 (0.68-1.2), respectively]. Seropositivity to HPV-18 was not associated with a decreased risk of infection with HPV-18 or its genetically related types (RR 1.3; 95% CI 1.0-1.8). Thus, we did not observe immunity, although a protective effect from natural infection cannot be excluded because of the limits of available assays and study designs.  相似文献   
76.
Women infected with multiple human papillomavirus (HPV) types seem to be at higher risk of cervical intraepithelial neoplasia, although there is controversy about whether coinfections are associated with lower or higher grades of dysplasia. There is no established risk factor profile for infection with multiple HPV types. We analyzed data from a prospective cohort of 2,075 Brazilian women to identify determinants of HPV coinfection. Cervical specimens were collected for cytology and HPV DNA detection. Data on baseline and time-dependent putative risk factors were obtained by interview. Baseline predictors of HPV coinfection included younger age, greater number of recent sexual partners, a history of condyloma but not of other sexually transmitted diseases, and younger age at first sexual intercourse. In repeated measures analyses, there was a weak positive association between the number of sexual partners in the time interval between two study visits and the risk of coinfection. Our results suggest that the risk factor profile for HPV coinfection among HPV-infected women shares several similarities with risk factors for any HPV infection.  相似文献   
77.
PURPOSE: Recent studies have shown that tissue factor (TF) may be involved in tumor angiogenesis and metastasis. The role of TF in hepatocellular carcinoma (HCC) was unknown. This study evaluated whether TF expression correlates with microvessel density (MVD), vascular endothelial growth factor (VEGF) expression, tumor invasiveness, and prognosis in human HCC. EXPERIMENTAL DESIGN: Tissue samples were obtained from 58 specimens of resected HCC. Immunohistochemical expression of TF was examined, and tumor MVD was evaluated using CD34 as the endothelial marker. TF and VEGF protein levels in the tumor cytosol were quantified by ELISA. Clinicopathologic and follow-up data of patients were prospectively collected. RESULTS: The immunohistochemical expression of TF in the tumors correlated significantly with tumor MVD (P = 0.002). The median cytosolic TF protein level in the tumors was 720 pg/mg total protein (range, 67-2406 pg/mg total protein). A significant positive correlation was found between TF and VEGF levels in the tumor cytosol (r = 0.475, P < 0.001). High tumor cytosolic TF level was associated with venous invasion (P = 0.004), microsatellite nodules (P = 0.024), unencapsulated tumor (P = 0.007), and advanced tumor stage (P = 0.010). A higher than median tumor cytosolic TF level was an independent predictor of poor survival (risk ratio, 1.836; 95% confidence interval 1.130-5.312, P = 0.023). CONCLUSIONS: This study shows that TF is related to tumor angiogenesis and invasiveness in HCC. Evaluation of tumor TF expression may be useful as a prognostic indicator in patients with HCC.  相似文献   
78.
OBJECTIVE: To investigate the knowledge of reproductive physiology and anatomy among adolescents and young adults in Sweden, and to evaluate the education obtained on these issues. METHODS: Two hundred and nine study specific questionnaires were distributed, of which 206 were answered by students in primary school, upper secondary school and at first year of university. A total knowledge score based on 21 out of the 35 questions in the questionnaire was calculated. As only 44 of the 206 respondents answered all the questions a revised score was also calculated, in which partial dropouts were interpreted as wrong answers. RESULTS: The mean of the total knowledge score was 28.7 out of 54 among the 44 respondents answering all questions, and the revised knowledge score was 24.0. The level of knowledge tended to be higher in older age groups, among women, as well as among respondents who had visited a Youth clinic. The time of ovulation was known by 21.4% of men compared to 63.4% of women. Almost 50% of the students knew one mechanism whereby oral contraceptives act to protect against pregnancy. Of the respondents, 77.2% knew of Chlamydia trachomatis but the knowledge of other STIs, like condyloma, was poorer (16.5%). Reasons for infertility were relatively well known among the respondents. Of the respondents, 57.5% stated that they had not received enough information on reproductive issues. CONCLUSIONS: The students have not achieved sufficient knowledge concerning sexual and reproductive matters that they, according to the national curriculum, should have attained by the end of the 9th grade. An improvement of the quality of the education, adapted to the students' age and pre-existing knowledge, and a review of the contents of the education is therefore needed.  相似文献   
79.
80.
Anxiety and panic are the most common adverse effects of cannabis intoxication; reactions potentiated by stress. Data suggest that cannabinoid (CB1) receptor modulation of amygdalar activity contributes to these phenomena. Using Fos as a marker, we tested the hypothesis that environmental stress and CB1 cannabinoid receptor activity interact in the regulation of amygdalar activation in male mice. Both 30 min of restraint and CB1 receptor agonist treatment (Delta9-tetrahydrocannabinol (2.5 mg/kg) or CP55940 (0.3 mg/kg); by i.p. injection) produced barely detectable increases in Fos expression within the central amygdala (CeA). However, the combination of restraint and CB1 agonist administration produced robust Fos induction within the CeA, indicating a synergistic interaction between environmental stress and CB1 receptor activation. An inhibitor of endocannabinoid transport, AM404 (10 mg/kg), produced an additive interaction with restraint within the CeA. In contrast, fatty acid amide hydrolase (FAAH) inhibitor-treated mice (URB597, 1 mg/kg) and FAAH-/- mice did not exhibit any differences in amygdalar activation in response to restraint compared to control mice. In the basolateral (BLA) and medial amygdala, restraint stress produced a low level of Fos induction, which was unaffected by cannabinoid treatment. Interestingly, the CB1 receptor antagonist SR141716 dose-dependently increased Fos expression in the BLA and CeA. These data suggest the CeA is an important neural substrate subserving the interactions between cannabinoids and environmental stress, and could be relevant to understanding the context-dependent emotional and affective changes induced by marijuana intoxication and the role of endocannabinoid signaling in the modulation of amygdalar activity.  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