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   2468篇
  免费   96篇
  国内免费   15篇
耳鼻咽喉   67篇
儿科学   85篇
妇产科学   8篇
基础医学   343篇
口腔科学   106篇
临床医学   233篇
内科学   580篇
皮肤病学   12篇
神经病学   203篇
特种医学   104篇
外科学   345篇
综合类   9篇
一般理论   1篇
预防医学   134篇
眼科学   28篇
药学   131篇
中国医学   1篇
肿瘤学   189篇
  2023年   6篇
  2022年   11篇
  2021年   34篇
  2020年   21篇
  2019年   33篇
  2018年   35篇
  2017年   25篇
  2016年   41篇
  2015年   40篇
  2014年   67篇
  2013年   114篇
  2012年   136篇
  2011年   159篇
  2010年   109篇
  2009年   82篇
  2008年   139篇
  2007年   176篇
  2006年   157篇
  2005年   150篇
  2004年   167篇
  2003年   180篇
  2002年   179篇
  2001年   33篇
  2000年   16篇
  1999年   30篇
  1998年   31篇
  1997年   36篇
  1996年   27篇
  1995年   25篇
  1994年   30篇
  1993年   27篇
  1992年   23篇
  1991年   27篇
  1990年   17篇
  1989年   18篇
  1988年   12篇
  1987年   7篇
  1986年   11篇
  1985年   17篇
  1984年   17篇
  1983年   15篇
  1982年   21篇
  1981年   8篇
  1980年   12篇
  1979年   6篇
  1978年   12篇
  1977年   14篇
  1976年   7篇
  1975年   6篇
  1957年   2篇
排序方式: 共有2579条查询结果,搜索用时 15 毫秒
61.
Emotional excitement may trigger cardiovascular (CV) events, particularly in patients with coronary artery disease (CAD). Our aim was to compare changes in various biomarkers in CAD patients and age-matched healthy male subjects during “real-life” emotional excitement. Enthusiastic male ice hockey spectators (CAD n = 18, healthy subjects n = 16) attended Finnish national ice hockey play-off matches. Heart rate variability, plasma catecholamines, endothelin-1 (ET-1) and interleukin-6 (IL-6) were determined at the baseline and during the match. A significantly more marked increase in both ET-1 and IL-6 was observed in CAD patients compared with healthy subjects during the match (time × group interaction p = 0.009 and p = 0.018 for ET-1 and IL-6, respectively). The high-frequency power of R–R intervals decreased in CAD patients (p < 0.001) but did not change in healthy subjects (p = ns, time × group interaction p < 0.001). Changes in adrenaline and noradrenaline did not differ between the groups. Emotional excitement causes more marked increases of markers of vasoconstriction and acute inflammation and withdrawal of cardiac vagal regulation in patients with CAD.  相似文献   
62.
The objective of this study was to assess the quality of oral health record-keeping in public oral health care in relation to dentists' characteristics. A random computerized selection of 239 subjects, born in 1966-71 and clinically examined during 1994 in an administrative unit of the public oral health service in southern Finland, included 4-5 cases per dentist, the number of dentists being 50. Data concerning actual clinical examinations and treatment courses carried out in public dental clinics came from original oral health records. Criteria for assessment of oral health record entries were based on Finnish health legislation and detailed instructions of health authorities. The results showed that each patient's identity was available in 90% of documents. Recordings concerning continuity of comprehensive care were infrequent; a questionnaire concerning each patient's up-to-date health history was in only 26% of the oral health records. Notes concerning each patient's bite and function of the temporomandibular joint were in 37% of the records, notes about oral soft tissues were in 11%, and the check-up interval was recorded in 21%. Recording of indices on periodontal and dental status varied greatly; the community periodontal index of treatment need was found in 93% and the index of incipient lesions in 16% of the records. Female dentists and dentists younger than 37 years tended to record more information. Dentists should be encouraged to better utilize the options offered by oral health records for individual treatment schemes.  相似文献   
63.
64.
Hantaviruses, Leptospira spp., and Babesia spp. are rodent-borne pathogens present worldwide. We studied multiple co-infections of small rodents in Croatia with all three pathogens. Twenty-eight Apodemus flavicollis and 16 Myodes glareolus were tested for the presence of hantavirus RNA by real-time RT-PCR, Leptospira strains by renoculture method and Babesia DNA by PCR. Anti-hantavirus antibodies and anti-Leptospira antibodies were detected by serological methods. Very high infection rates with each pathogen were found in A. flavicollis: 20 of 28 rodents (71%) were infected with Dobrava virus, 13 rodents (46%) were infected with Leptospira, and 5 rodents (18%) were infected with Babesia. Multiple co-infections with all three pathogens were found in 3 of 28 (11%) A. flavicollis animals, suggesting that the same rodent host can be infected with several pathogens at the same time. Dual infections with both hantaviruses and Leptospira were found in 7 of 44 rodents (16%), with hantaviruses and Babesia in 2 rodents (5%), and double infection with both Leptospira and Babesia were found in 1 rodent (2%). Since hantaviruses, Leptospira, and Babesia have similar geographical distributions, it is to be expected that in other parts of the world multiple co-infections, representing a serious threat to public health, can be found.  相似文献   
65.
66.
67.
Although DNA aneuploidy and high proliferative activity (S-phase fraction, SPF) of tumour cells, measured by flow cytometry, have proved to be indicators of poor prognosis in most solid tumours, there have been conflicting results in lung cancer studies. During a four-year period we studied the prognostic significance of DNA ploidy and SPF in 99 surgically treated lung cancer patients. Flow cytometric analysis was done from archival, formalin-fixed, paraffin-embedded tumour specimens. DNA index and SPF were determined, using MultiCycle software with sliced nuclear correction to compensate for debris. There were 61 DNA diploid and 38 DNA aneuploid tumours. The median SPF was 10.2%. Neither ploidy nor SPF was associated with previously known prognostic factors. Survival was poorer in patients with aneuploid tumours than in the other patients, but the difference was not statistically significant. DNA ploidy and SPF thus do not seem to be useful prognostic indicators in surgically treated lung cancer.  相似文献   
68.
The necessity for postoperative inhaled nitric oxide (NO) therapy and predictive factors for that need were retrospectively analysed in 457 paediatric patients at risk of pulmonary hypertensive events following open-heart surgery for congenital heart disease. Inhaled NO was given postoperatively to 46% of the study group and to 23% of all patients undergoing open-heart surgery during the study period. Factors associated with increased need for postoperative NO were age &lt;1 year, Down's syndrome, preoperative pulmonary hypertension and increased pulmonary vascular resistance. Using a multivariate model based on these factors, 73% of the patients who were given NO were identified. Thus, in a setting with unrestricted access to NO therapy, almost half of the patients with cardiac lesions that commonly give rise to postoperative pulmonary hypertension were given postoperative NO. Seventy-three percent of postoperative NO treatment was associated with a relatively small number of pre- and perioperative patient-related risk factors.  相似文献   
69.
This study reports a rehabilitation training for unilateral visual neglect combining a visual training programme and arm activation. Four cases of left visual neglect are presented with differing arm use. Neglect impairment was assessed using seven neuropsychological tests at weekly intervals for nine weeks: three weeks before, during and after the treatment period. In addition, one patient was followed over a longer time period. The treatment consisted of both a visual training programme and simultaneous arm activation. Considerable improvement in three of the four patients was observed in article reading. Moreover, all patients showed some improvement on three cancellation tests, whereas there was no improvement on other tests. In particular, the patients who had full hand or shoulder movement showed improvement in their performance. These results point out the usefulness of combined visual training and arm activation in the rehabilitation of visual neglect.  相似文献   
70.

Key points

  • Aerobic exercise, such as running, enhances adult hippocampal neurogenesis (AHN) in rodents.
  • Little is known about the effects of high‐intensity interval training (HIT) or of purely anaerobic resistance training on AHN.
  • Here, compared with a sedentary lifestyle, we report a very modest effect of HIT and no effect of resistance training on AHN in adult male rats.
  • We found the most AHN in rats that were selectively bred for an innately high response to aerobic exercise that also run voluntarily and increase maximal running capacity.
  • Our results confirm that sustained aerobic exercise is key in improving AHN.

Abstract

Aerobic exercise, such as running, has positive effects on brain structure and function, such as adult hippocampal neurogenesis (AHN) and learning. Whether high‐intensity interval training (HIT), referring to alternating short bouts of very intense anaerobic exercise with recovery periods, or anaerobic resistance training (RT) has similar effects on AHN is unclear. In addition, individual genetic variation in the overall response to physical exercise is likely to play a part in the effects of exercise on AHN but is less well studied. Recently, we developed polygenic rat models that gain differentially for running capacity in response to aerobic treadmill training. Here, we subjected these low‐response trainer (LRT) and high‐response trainer (HRT) adult male rats to various forms of physical exercise for 6–8 weeks and examined the effects on AHN. Compared with sedentary animals, the highest number of doublecortin‐positive hippocampal cells was observed in HRT rats that ran voluntarily on a running wheel, whereas HIT on the treadmill had a smaller, statistically non‐significant effect on AHN. Adult hippocampal neurogenesis was elevated in both LRT and HRT rats that underwent endurance training on a treadmill compared with those that performed RT by climbing a vertical ladder with weights, despite their significant gain in strength. Furthermore, RT had no effect on proliferation (Ki67), maturation (doublecortin) or survival (bromodeoxyuridine) of new adult‐born hippocampal neurons in adult male Sprague–Dawley rats. Our results suggest that physical exercise promotes AHN most effectively if the exercise is aerobic and sustained, especially when accompanied by a heightened genetic predisposition for response to physical exercise.

Abbreviations

AHN
adult hippocampal neurogenesis
BDNF
brain‐derived neurotrophic factor
BrdU
bromodeoxyuridine
HIT
high‐intensity interval training
HRT
high‐response trainer
LRT
low‐response trainer
RW
running wheel
Sed
sedentary
TBS
Tris‐buffered saline
V˙O2max
maximal oxygen uptake
  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