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   17150篇
  免费   693篇
  国内免费   163篇
耳鼻咽喉   204篇
儿科学   289篇
妇产科学   186篇
基础医学   2094篇
口腔科学   546篇
临床医学   1141篇
内科学   3967篇
皮肤病学   218篇
神经病学   1379篇
特种医学   731篇
外科学   3011篇
综合类   92篇
预防医学   560篇
眼科学   222篇
药学   1203篇
中国医学   25篇
肿瘤学   2138篇
  2023年   85篇
  2022年   158篇
  2021年   259篇
  2020年   154篇
  2019年   179篇
  2018年   275篇
  2017年   183篇
  2016年   236篇
  2015年   238篇
  2014年   356篇
  2013年   417篇
  2012年   688篇
  2011年   681篇
  2010年   456篇
  2009年   405篇
  2008年   685篇
  2007年   728篇
  2006年   727篇
  2005年   757篇
  2004年   715篇
  2003年   713篇
  2002年   735篇
  2001年   778篇
  2000年   782篇
  1999年   709篇
  1998年   253篇
  1997年   195篇
  1996年   191篇
  1995年   139篇
  1994年   114篇
  1993年   111篇
  1992年   465篇
  1991年   408篇
  1990年   377篇
  1989年   459篇
  1988年   378篇
  1987年   332篇
  1986年   357篇
  1985年   337篇
  1984年   248篇
  1983年   157篇
  1982年   73篇
  1979年   144篇
  1978年   100篇
  1977年   86篇
  1975年   80篇
  1974年   75篇
  1973年   75篇
  1969年   92篇
  1967年   87篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
It has been known that clarithromycin (TE-031, A-56268), a new macrolide antibiotic (ML), achieves higher concentrations in blood, is better excreted into urine and is better distributed into various tissues than conventional MLs. We investigated the pharmacokinetics of TE-031 in children upon oral administration of the drug in the following method. TE-031 granular preparation with a potency of 100 mg/g was given to 6 boys (5 years 4 months-14 years 0 month) with dose levels of 5 mg/kg and 10 mg/kg for each 3 boys. A tablet preparation with each tablet containing 50 mg of TE-031 was administered to 4 boys and 2 girls (8 years 5 months-11 years 6 months) with dose level of 2 tablets (i.e., 100 mg) and 3 tablets (i.e., 150 mg) for each 3 children. All administrations were done at 30 minutes before meal. Then, to conduct a cross-over test, the granule preparation was given orally to the 3 children mentioned above who was given 2 tablets and the 1 of 3 cases that were given 3 tablets at the same dose levels (100 mg and 150 mg) respectively. A bioassay was used to determine concentrations in blood of active antibiotic compounds and an high performance liquid chromatography (HPLC) was used to determine unchanged TE-031 and its main metabolite, M-5. Urinary concentrations of active antibiotic compounds were also determined by the bioassay and the HPLC was used to determine concentrations and proportions of unchanged TE-031 and its metabolites, M-1, M-4, M-5, M-6 and M-7 to figure out the urinary recovery rate in the first 6 hours. The results of these experiments are summarized as follows. 1. As was mentioned above, TE-031 was administered orally to 2 groups of children at dose levels of 5 mg/kg and 10 mg/kg, respectively. Mean serum levels of total active antibiotic compounds reached their maximum in 1 and 2 hours for the 5 mg/kg and the 10 mg/kg dosage groups, respectively, at 1.28 and 3.62 micrograms/ml, respectively. Mean half lives of serum concentrations in the 2 groups were quite similar, with values of at 2.1 and 2.0 hours, respectively. Mean serum concentrations of unchanged TE-031 determined by the HPLC method reached their peaks in 1 hour after administration in either of the 5 and 10 mg/kg dosage groups at peak levels of 0.65 micrograms/ml and 2.67 micrograms/ml, respectively. Thus, dose-response relationships were observed with TE-031 and M-5.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
62.
Calcified stenotic aortic valve are usually replaced by the artificial valve. Recently, we are trying to decalcify the calcification of the aortic valve by ultrasonic energy. This case report reviewed a small physique, 47 year old female, who had the calcified stenotic bicuspid aortic valve and the narrow aortic valve ring (18 mm diameter). The ultrasonic decalcification was performed by the ultrasonic surgical instrument, SUS-201D (ALOKA), ultrasonic energy output range from 25% to 45%. After the ultrasonic decalcification, the movability of the aortic cusps were improved and the aortic opening was enlarged. The systolic pressure gradient across the aortic valve was improved from 100 mmHg to 20 mmHg. This method "ultrasonic decalcification" is very useful technique for the repair of the calcified aortic valve stenosis.  相似文献   
63.
Collapsin response mediating protein-2 (CRMP2) has been identified as an intracellular protein mediating Semaphorin3A (Sema3A), a repulsive guidance molecule. In this study, we demonstrate that cyclin-dependent kinase 5 (Cdk5) and glycogen synthase kinase 3beta (GSK3beta) plays a critical role in Sema3A signalling. In In vitro kinase assay, Cdk5 phosphorylated CRMP2 at Ser522, while GSK3beta did not induce any phosphorylation of CRMP2. Phosphorylation by GSK3beta was exclusively observed in Cdk5-phosphorylated CRMP2, but barely in CRMP2T509A. These results indicate that Cdk5 primarily phosphorylates CRMP2 at Ser522 and GSK3beta secondarily phosphorylates at Thr509. The dual-phosphorylated CRMP2, but not non-phosphorylated or single-phosphorylated CRMP2, is recognized with the antibody 3F4, which is highly reactive with the neurofibrillary tangles of Alzheimer's disease. 3F4 recognized the CRMP2 in the wild-type but not cdk5-/- mouse embryonic brain lysates. The phosphorylation of CRMP2 at Ser522 caused reduction of its affinity to tubulin. In dorsal root ganglion neurones, Sema3A stimulation enhanced the levels of the phosphorylated form of CRMP2 detected by 3F4. Over-expression of CRMP2 mutant substituting either Ser522 or Thr509 to Ala attenuates Sema3A-induced growth cone collapse response. These results suggest that the sequential phosphorylation of CRMP is an important process of Sema3A signalling and the same mechanism may have some relevance to the pathological aggregation of the microtubule-associated proteins.  相似文献   
64.
65.
We report here that loss of the Sprouty2 gene (also known as Spry2) in mice resulted in enteric nerve hyperplasia, which led to esophageal achalasia and intestinal pseudo-obstruction. Glial cell line-derived neurotrophic factor (GDNF) induced hyperactivation of ERK and Akt in enteric nerve cells. Anti-GDNF antibody administration corrected nerve hyperplasia in Sprouty2-deficient mice. We show Sprouty2 to be a negative regulator of GDNF for the neonatal development or survival of enteric nerve cells.  相似文献   
66.
67.
Ovarian juvenile granulosa cell tumor associated with Maffucci's syndrome.   总被引:5,自引:0,他引:5  
A 15-year-old girl developed a juvenile granulosa cell tumor associated with Maffucci's syndrome (enchondromatosis + hemangiomas). Clinical manifestations of the disease included an abdominal mass and progressive anemia. She underwent the removal of a Stage Ic juvenile granulosa cell tumor and subsequent adjuvant chemotherapy. On follow-up examination 4 years later, no recurrence of the ovarian tumor was noted. A review of the literature showed 10 previous cases of juvenile granulosa cell tumor associated with enchondromatosis, two associated with Maffucci's syndrome, and the rest with Ollier's disease (enchondromatosis). Ovarian juvenile granulosa cell tumor may occur not infrequently in female patients with enchondromatosis in the first or second decades, in contrast to the widely recognized sarcomatous changes of enchondromas that usually occur after the second decade. Data provided from these cases also emphasize the concept of a generalized mesodermal dysplasia.  相似文献   
68.
Adenohypophyses of porcine fetuses from 25 to 110 days of gestation were studied by immunohistochemical staining to ascertain the ontogeny of specific cell types and their spatial distribution in the pars distalis. No hormonecontaining cells were found before 30 days of gestation. ACTH cells were observed first at 40 days, while GH and LH cells appeared first at 60 days. PRL cells were initially detected at 105 days. ACTH immunoreactive cells were also observed in the pars intermedia at 40 days. Blood capillaries were interposed between cell cords of the pars distalis after 40 days of gestation. ACTH cells were evenly distribution in all areas of the pars distalis except the rostal area (sex zone). GH cells were densely distributed in lateral wings of the pars distalis and immediately anterior to Rathke's lumen. PRL cells resembled GH cells in their distribution pattern, but PRL cells were fewer in number. LH cells were scattered in the sex zone of the pars distalis from 60 to 80 days of gestation. After 90 days, they became scattered throughout the pars distalis but were more numerous in the sex zone than in other areas. The inductive elements of adenohypophysial cells from Rathke's pouch epithelia are discussed. We hypothesize that cell cords of specific areas facing Rathke's lumen may differentiate into specific cell types of the pars distalis during fetal life. © 1992 Wiley-Liss, Inc.  相似文献   
69.
A typical case of the D uchenne type of progressive muscular dystrophy with autopsy findings was presented. Changes in the myocardial and smooth muscle of many organs were found, and the skeletal muscles also revealed florid changes.
Histopathological examination of the skeletal muscle was made in detail through light and electron microscopic observation.  相似文献   
70.
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