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   959篇
  免费   55篇
  国内免费   20篇
耳鼻咽喉   4篇
儿科学   30篇
妇产科学   11篇
基础医学   70篇
口腔科学   63篇
临床医学   180篇
内科学   224篇
皮肤病学   7篇
神经病学   16篇
特种医学   160篇
外科学   78篇
综合类   26篇
一般理论   1篇
预防医学   60篇
药学   32篇
肿瘤学   72篇
  2023年   10篇
  2022年   14篇
  2021年   23篇
  2020年   7篇
  2019年   16篇
  2018年   18篇
  2017年   12篇
  2016年   14篇
  2015年   12篇
  2014年   28篇
  2013年   38篇
  2012年   25篇
  2011年   36篇
  2010年   32篇
  2009年   49篇
  2008年   20篇
  2007年   29篇
  2006年   18篇
  2005年   20篇
  2004年   11篇
  2003年   14篇
  2002年   23篇
  2001年   21篇
  2000年   21篇
  1999年   13篇
  1998年   41篇
  1997年   40篇
  1996年   39篇
  1995年   37篇
  1994年   25篇
  1993年   27篇
  1992年   13篇
  1991年   12篇
  1990年   10篇
  1989年   26篇
  1988年   28篇
  1987年   17篇
  1986年   13篇
  1985年   22篇
  1984年   12篇
  1983年   11篇
  1982年   21篇
  1981年   16篇
  1980年   18篇
  1979年   5篇
  1978年   11篇
  1977年   11篇
  1976年   11篇
  1973年   14篇
  1972年   7篇
排序方式: 共有1034条查询结果,搜索用时 0 毫秒
1.
2.
Coronary artery bypass grafts: visualization with MR imaging   总被引:1,自引:0,他引:1  
Gomes  AS; Lois  JF; Drinkwater  DC  Jr; Corday  SR 《Radiology》1987,162(1):175
  相似文献   
3.
表小檗碱对α受体的作用   总被引:2,自引:0,他引:2  
王嘉陵  方达超 《药学学报》1990,25(4):289-292
表小檗碱(epiberberine,EB)是从湖北产黄连(Coptis chinensis Franch)中提取的一种生物碱,属苯喹嗪类原小檗碱,对其药理作用的研究资料甚少,未见其对α肾上腺素体作用的报道。资料表明,许多原小檗碱类化合物有α受体阻滞作用,为从该类化合物中选择  相似文献   
4.
The purpose of this pilot study was to observe both relaxed and deep breathing patterns in a convenience sample to determine the incidence of normal versus faulty patterns of respiration. These observations were then combined with respondent answers to a survey on pain history to determine if there is any correlation between faulty breathing and musculo-skeletal pain patterns. If such a correlation can be made, then we propose that clinicians working with chronic pain patients may have improved outcomes if they address and correct faulty breathing patterns. Based on this study, it is suggested to include the evaluation and treatment of faulty respiration in the rehabilitation of chronic musculo-skeletal conditions, most notably cervical pain.  相似文献   
5.
Centrally acting cholinergic agents induce the immediate early gene c-fos in the rat brain resulting in transient increases of Fos protein, most notably in the cerebral cortex. In this study we have monitored by Fos immunohistochemistry the effect of the acetylcholine release enhancer linopirdine (DUP996) on the immediate early gene c-fos in brains of 3 months and 30 months old rats. In young rats linopirdine had only a marginal effect on Fos expression. In contrast, in aged rats linopirdine caused widespread expression of Fos throughout neocortex. In somatosensory cortex, the induction of the c-fos gene by linopirdine was nearly completely blocked by atropine and scopolamine and strongly attenuated by the NMDA receptor blockers CPP and MK-801. The results suggest that the age-related decline in acetylcholine release in rodents can be partially compensated for by administration of linopirdine.  相似文献   
6.
Summary The venous architecture in donor flaps was observed in 17 fresh cadavers by injection of latex or ink into the vessels or by making corrosion-cast specimens. The pattern of the veins resembles that of the arteries, with the difference that there is another set of venous trunks which do not accompany the arteries. Because these trunks are of larger caliber, they are the main drainage route for flaps. There are three types of drainage based on the anatomical architecture: 1) the superficial trunk is the main drainage path; 2) the deep trunk is the main path; 3) both superficial and deep veins are involved. These morphological considerations are the basis for selection of veins for anastomosis in microsurgery. The axial veins in temporal, frontal and facial flaps on the dorsum of the hand and the foot usually loosely accompany the axial arteries. The characteristics of these vascular pedicules should be studied in transplant operation.
Bases anatomiques du drainage veineux des lambeaux cutanés libres
Résumé Le drainage veineux des lambeaux cutanés libres a été étudié sur 17 cadavres frais par injection de latex ou d'encre dans les vaisseaux, ou en réalisant des moulages par injection-corrosion. La distribution des veines ressemble à celle des artères à la différence près qu'il existe des troncs veineux qui n'accompagnent pas les artères. Ces troncs ont un calibre plus important et représentent une voie de drainage principale pour les lambeaux. On peut individualiser trois types de drainages basés sur l'architecture veineuse : 1. Le tronc superficiel est la principale voie de drainage ; 2. le tronc profond est la principale voie; 3. les veines superficielles et profondes sont impliquées simultanément. Ces considérations morphologiques sont les bases de la sélection des axes veineux pour les anastomoses en micro-chirurgie. Les veines axiales au niveau temporal, frontal et facial et pour les lambeaux de la face dorsale de la main et du pied sont habituellement relativement éloignées du trajet artériel. Les caractéristiques de ces pédicules veineux doivent être précisées pour la réalisation des lambeaux.
  相似文献   
7.
Y chromosome deletions encompassing the AZFc region have been reported in 13% of azoospermic men and 7% of severely oligozoospermic men. We examined the impact of these Y deletions on the severity of testicular defects in 51 azoospermic men undergoing intracytoplasmic sperm injection (ICSI) after testicular sperm extraction (TESE) and 30 men with severe oligozoospermia undergoing ICSI after ejaculation of spermatozoa. In addition, five azoospermic patients shown previously to have Y chromosome deletions underwent histological evaluation of their previously obtained testis biopsy specimens. A further 27 azoospermic men underwent TESE-ICSI, but not Y chromosome DNA testing. Ten of 51 azoospermic men (20%) who underwent TESE-ICSI and Y-DNA testing were found to be deleted for portions of the Y chromosome AZFc region. Of these 10, five had spermatozoa retrievable from the testis, and in two cases the wives became pregnant. Of the 41 azoospermic men with no Y chromosome deletion, 22 (54%) had spermatozoa retrievable from the testis, and in 12 cases (29%) the wives became pregnant. Four of 30 (13%) severely oligozoospermic patients were found to be deleted for AZFc and in three (75%) of these pregnancy was achieved. The other 26 severely oligozoospermic couples who had no AZFc deletions underwent ICSI, and 12 (46%) have an ongoing or delivered pregnancy. The embryo implantation rate was not significantly different for azoospermic (22%), oligozoospermic (16%), Y-deleted (14%) or Y-intact (18%) men. Of the total of 19 infertile men who had Y chromosome deletions, 14 had deletions within Y chromosome intervals 6D-6F, in the AZFc region. Twelve of those 14 had some spermatozoa (however few in number) in the ejaculate or testis. Five of the Y-deleted men had deletions that extended more proximally on the Y chromosome, and in none of these could any spermatozoa be observed in either ejaculate or testis. These results support the concept that, in azoospermic or oligozoospermic men with Y chromosome deletions limited to intervals 6D-6F (AZFc), there are generally very small numbers of testicular or ejaculated spermatozoa. Larger Y deletions, including and extending beyond the AZFc region and encompassing more Y genes, tend to be associated with a total absence of testicular spermatozoa. In those cases where spermatozoa were retrieved, the presence of Y deletions had no obvious impact on fertilization or pregnancy rate.   相似文献   
8.
Preparations of human placental alkaline phosphatase differing in specific enzyme activities were compared by microcomplement fixation assays using monospecific antisera. While both specific enzyme activity and complement fixation units increased 15,000-fold upon purification, the ratio between these units remained constant. Separation of an alkaline phosphatase preparation into 'A' and 'B' forms by ampholine isoelectric focusing indicated that these forms also possessed the same ratio of immunoreactive enzyme protein to enzyme activity. The correspondence of complement fixation units with specific enzyme activity indicates that complement fixation with monospecific antisera can be used to analyze structural differences among alkaline phosphatase isoenzymes.  相似文献   
9.
Archives of Sexual Behavior - Changes to how gay, bisexual, and other men who have sex with men (GBM) connect with each other and with their communities have implications for HIV prevention. Social...  相似文献   
10.
Davis  GD; Fulton  RE; Ritter  DG; Mair  DD; McGoon  DC 《Radiology》1978,128(1):133-144
Of 181 patients with severe congenital pulmonary atresia and ventricular septal defect or "type IV truncus" (an obsolete term), all but 11% had true central pulmonary arteries. These arteries were demonstrable by large serial biplane angiograms using multiple selective injections into collateral vessels, frequent photographic subtraction, and occasional pulmonary vein-wedge angiograms. These techniques are extremely important for accurate diagnosis and in planning corrective or palliative surgery, which was done in 77% of patients with pulmonary arteries.  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