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   188991篇
  免费   1595篇
  国内免费   100篇
耳鼻咽喉   1341篇
儿科学   6916篇
妇产科学   3101篇
基础医学   17951篇
口腔科学   1903篇
临床医学   13214篇
内科学   34477篇
皮肤病学   910篇
神经病学   17574篇
特种医学   9277篇
外科学   31264篇
综合类   2368篇
预防医学   18440篇
眼科学   3038篇
药学   10428篇
中国医学   646篇
肿瘤学   17838篇
  2023年   82篇
  2022年   209篇
  2021年   339篇
  2020年   207篇
  2019年   269篇
  2018年   22185篇
  2017年   17558篇
  2016年   19749篇
  2015年   1204篇
  2014年   1192篇
  2013年   1215篇
  2012年   7679篇
  2011年   21738篇
  2010年   19255篇
  2009年   11849篇
  2008年   20148篇
  2007年   22369篇
  2006年   1265篇
  2005年   2898篇
  2004年   4011篇
  2003年   4929篇
  2002年   3136篇
  2001年   667篇
  2000年   851篇
  1999年   530篇
  1998年   353篇
  1997年   333篇
  1996年   226篇
  1995年   195篇
  1994年   185篇
  1993年   141篇
  1992年   284篇
  1991年   308篇
  1990年   316篇
  1989年   318篇
  1988年   233篇
  1987年   222篇
  1986年   177篇
  1985年   183篇
  1984年   130篇
  1983年   111篇
  1982年   71篇
  1980年   81篇
  1979年   100篇
  1978年   69篇
  1974年   72篇
  1972年   64篇
  1970年   68篇
  1969年   75篇
  1968年   72篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
32.
Haemangiomas are the most common tumours of infancy. They typically proliferate then involute with considerable variation as regards to their rates of proliferation and involution. Haemangioma of the nasal tip is a lesion of special characteristics. During proliferation, it expands, contracts and deviates the nasal cartilages. Particularly, it regresses slowly and frequently involutes incompletely. That is why excision of the lesion is frequently suggested. The present study was conducted to evaluate open rhinoplasty after initial non-excision treatment modalities namely, intra-lesional corticosteroid injections and laser treatment, as a protocol of treatment for nasal tip haemangiomas. Twelve patients with nasal tip haemangiomas were included in the present study. Patients of both sexes, of different ages, with deep and mixed haemangiomas were studied. Disfigurement was the constant presenting symptom. Initial non-excision treatment reported different responses as denoted by the regression of the lesions’ size. Haemangiomas constantly extended between the medial crura of the alar cartilages as noted by the constant widening of the columella pre-operatively and the obvious separation of the nasal cartilages intra-operatively. This separation was constantly found to require approximation by sutures. The results of the present study concluded that whenever an early presentation with nasal tip haemangioma could be established, initial non-excision treatment followed by open rhinoplasty could be a useful protocol of treatment. Within the limitations of the present study, this protocol could achieve an early, safe and effective treatment for nasal tip haemangiomas with provisionally acceptable cosmetic outcomes so far.  相似文献   
33.
This study investigates whether tissue recoil or patient intrinsic factors influence the final position of the nipple areola complex (NAC) after reduction mammoplasty. The age, pre-operative ptosis, BMI and weight of the tissue resected were recorded as patient intrinsic factors in 37 patients undergoing reduction mammoplasty. The “spring-back” value was defined as the distance from the sternal notch to a nipple landmark on the breast meridian with the patient sitting up, minus the same measurement repeated with the patient recumbent to eliminate the pull of gravity on the breast. Spring back was measured pre-operatively for the nipple and nipple mark then post-operative for the nipple. The difference in centimeters between the final post-operative distance from the sternal notch to the nipple and the level intended by the pre-operative nipple mark was termed the “judgment error.” The final position of the post-operative nipple and the judgment error was compared to the spring-back values and patient intrinsic factors. Pre-operative ptosis was statistically related to increasing patient BMI and mass of tissue resected per breast. Pre-operative spring-back values for the nipple increased with increasing ptosis, BMI and decreasing age. Spring-back values were greater in the lower pole of the breast than in the upper pole. The final position of the nipple was higher than the pre-operative mark in 65% of cases, lower in 8% and as marked in 27% of cases. The post-operative NAC was, on average, 0.6 cm higher than planned pre-operatively. The post-operative distance from the sternal notch to the nipple increased with increasing pre-operative ptosis, mass of breast tissue resected per breast and all three spring-back values. The difference between the level of the pre-operative mark and the final nipple position showed a weak correlation with post-operative spring-back values. The parameters of ptosis, BMI, weight of tissue resected per breast and pre-operative nipple spring back reflect body habitus and breast size. Spring-back values vary between the upper and lower pole of the breast. The final NAC position was higher than that intended at pre-operative marking in the majority of cases. The surgeon instinctively marks the nipple lower in patients with greater pre-operative ptosis and in whom a larger resection is anticipated. Judgment error did not relate to intrinsic factors nor to pre-operative spring-back values; hence, these parameters cannot be applied as predictive tools for more accurate pre-operative marking of the nipple position. This study suggests that the pre-operative nipple mark should be placed, with the patient sitting up, at least 23 cm from the sternal notch and 0.6 cm lower than the final position estimated using the inframammary crease as a landmark. An invited commentary on this paper is available at .  相似文献   
34.
35.
Conclusions  Noninvasive imaging of neurohumoral upregulation in remodeled myocardium suggests that an imaging strategy can be developed for predicting the rate of remodeling and likelihood of HF development. This should allow a more judicious use of neurohumoral antagonists especially in subjects who do not have manifest HF.74 In others specific targeted imaging may allow timely selection of individualized treatment strategies and ensure optimization of therapeutic intervention. Similar to ACE and AII receptors, multiple other targets in the hormonal cascades can identify the likelihood of adverse and favorable remodeling.74  相似文献   
36.
Estramustine phosphate disodium (Estracyt) was used in the treatment of 38 patients with prostatic carcinoma for at least 1 year. Of these patients 37 patients were treated with Estracyt as primary treatment and 1 patient had been treated with another antiandrogenic therapy before the Estracyt treatment. Estracyt was given orally in a dose of 560 mg/day in divided oral doses. The clinical evaluation was done for the change of PAP, the relapse rate, the survival rate and the side effect. Among 22 cases which had shown abnormally high PAP values before the treatment started, the values decreased or normalized in 21 cases (95.5%) in the first year of administration of Estracyt. In 6 cases, however, the values increased again in the second year or later. Relapse was observed in 10 (26.3%) out of 38 cases. Relapse rate was 2.6%, 51.7%, and 51.7%, at the first, third, and fifth year, respectively. Survival rate was 97.4% at the first year, 88.5% at the third year, and 68.8% at the fifth year for the follow-up study. Side effects were observed in 14 (36.8%) out of 38 cases. The main side effect was gynecomastia. Gastro-intestinal disturbance and edema were also observed. However, there were only 2 cases (5.2%) in which administration of Estracyt had to be discontinued.  相似文献   
37.
We conducted a survey of 356 married couples and their 552 children living in Hisayama in Fukuoka prefecture in order to investigate the correlation between changes in obesity from adolescence to young adulthood. 1. A positive correlation between couples in weight and height could be found, but its coefficient was weak (r = 0.12, 0.10). There was no correlation between couples in BMI. 2. The correlation between parents and their children in height, weight and BMI was significantly positive (r = 0.18, 0.45), having a coefficient greater than that of the correlation between married couples. 3. The correlation coefficient between mother and child was greater than that of the correlation coefficient between father and child. 4. The BMI of a child with either parent obese was significantly greater than that of a child with neither parent obese. Obesity appeared more frequently in children whose BMI of parent was higher. 5. A positive correlation between the BMI of young adults and that of adolescents could be found, and the average BMI of the obesity group was higher than that of the non-obesity group even in the adolescent subjects. 6. Even after considering BMI during adolescence, the familial factor had a significant relationship to the BMI of young adulthood. These results suggest that obesity in adolescence will influence obesity in young adulthood, and that the appearance of obesity strongly correlates with the familial obesity factor. In conclusion, it is very important to take preventative measures, in cooperation with the family, early in a child's adolescent years in order to avoid obesity in adulthood.  相似文献   
38.
39.
The Nakano cataract gene, nct, was introduced into Balb/c mice by repeated backcrosses to elucidate the possible effects of background genes on its expression. The resulting congenic Balb/c-nct/nct mice were characterized by retarded and sporadic cataract formation with a tendency of further retardation in males and by the different disease process of cataract as compared with Nakano mice. The age of 50% cataract incidence was 60 days in females and 90 days in males compared with 22 days in Nakano mice, and lens opacification commenced in a diffuse, mild form at the cortex in congenic but in a pin-head, intense form at the core in Nakano mice. Sex hormones seemed to be involved in the difference in cateractogenesis between male and female mice. Microphthalmia was slighter in degree in Balb/c background mice. The results indicated that the nct-dependent cataractogenesis may be influenced by background genes and some non-hereditary factors. Balb/c-nct/nct mice will provide a new type of hereditary cataract model.  相似文献   
40.
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