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   1712篇
  免费   147篇
  国内免费   35篇
耳鼻咽喉   7篇
儿科学   40篇
妇产科学   64篇
基础医学   413篇
口腔科学   5篇
临床医学   119篇
内科学   110篇
神经病学   465篇
特种医学   76篇
外科学   168篇
综合类   189篇
预防医学   34篇
眼科学   6篇
药学   113篇
  1篇
中国医学   38篇
肿瘤学   46篇
  2024年   6篇
  2023年   33篇
  2022年   38篇
  2021年   51篇
  2020年   56篇
  2019年   44篇
  2018年   43篇
  2017年   54篇
  2016年   51篇
  2015年   58篇
  2014年   87篇
  2013年   85篇
  2012年   82篇
  2011年   100篇
  2010年   63篇
  2009年   75篇
  2008年   71篇
  2007年   69篇
  2006年   81篇
  2005年   79篇
  2004年   56篇
  2003年   46篇
  2002年   43篇
  2001年   35篇
  2000年   36篇
  1999年   26篇
  1998年   36篇
  1997年   40篇
  1996年   46篇
  1995年   29篇
  1994年   20篇
  1993年   20篇
  1992年   29篇
  1991年   18篇
  1990年   17篇
  1989年   18篇
  1988年   9篇
  1987年   15篇
  1986年   14篇
  1985年   19篇
  1984年   18篇
  1983年   17篇
  1982年   25篇
  1981年   11篇
  1980年   7篇
  1979年   4篇
  1978年   5篇
  1977年   2篇
  1976年   3篇
  1975年   3篇
排序方式: 共有1894条查询结果,搜索用时 15 毫秒
1.
AIM: To investigate the participation of adenosine receptors in the adenosine 5'-triphosphate (ATP)-induced relaxation in the corpus cavernosum penis (CCP) of rabbits. METHODS: The ATP-induced relaxation was assessed on the noradrenaline precontracted CCP of rabbits in the presence and absence of 8-(3-chlorostyryl)caffeine (CSC); an adenosine A(2A) receptor antagonist; alloxazine and MRS1754; adenosine A(2B) receptor antagonists; and ARL67156, an inhibitor of ecto-nucleoside triphosphate diphosphohydrolases. RESULTS: Adenosine and ATP relaxed the noradrenaline precontracted CCP of rabbits in a concentration-dependent manner. The adenosine- and ATP-induced relaxations were suppressed by alloxazine and MRS1754, but not by 8-(3-chlorostyryl)caffeine. ARL67156 potentiated the ATP-induced relaxation but not the adenosine-induced one. MRS1754 suppressed the ATP-induced relaxation potentiated by ARL67156. CONCLUSIONS: The above results suggest that, in the CCP of rabbits, the adenosine receptor mediating adenosine-induced relaxation is of the A(2B) receptor and the ATP directly causes relaxation through the A(2B) receptor on the CCP.  相似文献   
2.
3.
Since 1903, Marchiafava‐Bignami disease has been recognized as a rare syndrome with focal demyelination and necrosis in the corpus callosum, which is usually found in chronic alcoholics. It extends into the neighboring white matter and occasionally as far as the subcortical regions. We report a Japanese patient with Marchiafava‐Bignami disease associated with alcohol abuse, who had traveled around Western Europe, North America and China for more than 30 years. As he suffered extreme delirium in the early stages we administered a low dose (10 mg) of mianserin hydrochloride. He was very irritable and uncooperative on admission, after 20 days his delirium had disappeared and his temper had become very calm and mild. After 40 days, his intelligence level increased substantially as measured by various neuropsychological tests.  相似文献   
4.
The in-vitro oestradiol (E2) and progesterone (P) production by corpora lutea (CL) obtained at sterilization from 30 untreated women and 43 women treated with norethisterone (NET) 300 micrograms daily was measured. The CL were obtained at different stages of the luteal phase in the untreated women [luteinizing hormone (LH) 0 to +3, n = 7; LH +4 to +7, n = 7; LH +8 to +11, n = 9; LH +12 to menses, n = 7] and on days LH +8 to +11 or cycle days 22 to 26 in the NET-treated women. In the treated women, four types of ovarian reaction were identified. Four women showed ovarian reaction Type A (completely inhibited ovarian activity), 14 women Type B (marked follicular activity, but no luteal function), 12 women Type C (normal follicular activity, followed by insufficient luteal function) and 13 women Type D (apparently normal follicular and luteal activity). The CL were incubated in Eagle's medium with and without stimulation by human chorionic gonadotrophin (HCG) for 2 and 4 h. In the untreated women, P and E2 production increased significantly with both incubation time and stimulation by HCG throughout the luteal phase, except in the late luteal phase (LH +12 to menses) where P increased (P less than 0.01) only after 4 h stimulation by HCG. The maximal production of P was found after 4 h incubation with HCG stimulation of CL tissue in the early-mid luteal phase (LH +4 to +7).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
5.
目的:探讨阴茎包埋对海绵体内一氧化氮合酶(NOS)活性的影响。方法:通过建立大鼠隐匿阴茎模型获得实验标本,分2个月组、4个月组和6个月组进行观测,每组80只大鼠。各阶段中包括包埋组(n=50)、假手术组(n=15)和正常组(n=15)。称量大鼠体重和海绵体重量后,采用化学比色法检测海绵体内NOS活性。结果:各阶段包埋组阴茎海绵体重量、体重及两者的比值与正常组和假手术组比较均无显著性差异(P>0.05);包埋降低大鼠阴茎海绵体组织的NOS活性(2个月组P>0.05,4个月组P<0.05,6个月组P<0.01)。结论:阴茎包埋可影响海绵体内NOS活性,且与包埋时间呈正相关,但对海绵体外观和重量无明显影响。  相似文献   
6.
Primrose syndrome is a congenital malformation syndrome characterized by intellectual disability, developmental delay, progressive muscle wasting, and ear lobe calcification. Mutations in the ZBTB20 gene have been established as being accountable for this syndrome. In this study, a novel de novo ZBTB20 mutation, NM_001164342.2:c.1945C>T (p.Leu649Phe), has been identified through whole exome sequencing (WES) in a female patient presenting a typical Primrose phenotype. Because the present patient exhibited recurrent otitis media, detailed immunological examinations were performed in this study and subnormal immunoglobulin levels were firstly identified in a Primrose patient. Anatomical anomaly of the inner ear has never been reported in this patient and WES data did not include any relevant variants causally linked with the immunologic defect. Thus, there is a possibility of a relation between an unclassified immunodeficiency with selective IgG2 deficiency and Primrose syndrome and this may be the reason of recurrent otitis media frequently observed in Primrose patients. Because subnormal levels of IgG2 in this patient might be caused by an unrelated and still uncharacterized genetic cause, further studies are required to prove the causal link between aberrant ZBTB20 function and immunodeficiency.  相似文献   
7.
Structure of the corpus luteum in the ovulatory polycystic ovary.   总被引:2,自引:0,他引:2  
BACKGROUND: Women with polycystic ovaries (PCO) have a wide spectrum of presentation from anovulation and amenorrhoea to apparently regular, ovulatory menstrual cycles. We have recently reported a subtle defect in steroidogenic function in the luteal phase in the latter and an increase in the number of degenerating corpora lutea (CL) were observed in ovulatory PCO (ovPCO) during dissection. The possibility was therefore investigated of differences in structure or degeneration in CL formed during ovulatory cycles in women with PCO. METHODS: This study compared the histology of the CL in ovPCO with that in the normal ovary. Corpora lutea were collected from nine normal ovaries (days 1-27 of the cycle) and from 13 women with ovPCO (days 5-38). RESULTS: Variations in the degree of regression, both in relation to onset of menses and between different areas within individual CL, were recorded in both groups. During development and regression no obvious differences were observed between either group apart from an apparent increase in luteal haemorrhage, which was more common and more extensive in CL from PCO. CONCLUSIONS: The findings suggest that possible luteal phase abnormalities of steroid secretion in women with ovulatory PCO are not associated with obvious morphological defects in the CL, however it is possible that the persistence of luteal structures seen in PCO was a consequence of increased luteal haemorrhage.  相似文献   
8.
Cigarette smoking is accepted as a risk factor for pregnancybut its effect on fertility is uncertain. In this study we determinedthe concentration of cotinine, a nicotine metabolite, in follicularfluid and serum from women participating in an In-vitro fertilizationand embryo transfer (IVF-ET) programme. Cotinine was undetectableIn serum and follicular fluid of non-smokers but ranged from<5 to 371 ng/ml in follicular fluid and from 24 to 245 ng/mlin serum of smokers. Granulosa-luteal cells, obtained from IVFpatients and cultured for 4 days, secreted progesterone and,when an aromatizable androgen was added, oestradiol-17. Theaddition of cotinine or nicotine did not alter progesteroneor oestradlol-17 secretion. However, the presence of cotininein follicular fluid of women smokers provides evidence for accessof at least one component of cigarette smoke to the developinggamete and the cells of the follicle. Further work is requiredto determine whether fertllity is compromised by the presence,In follicular fluid, of contaminants derived from cigarettesmoke.  相似文献   
9.
A case of a clinically silent mature teratoma of the uterine corpus is reported. A 55-year-old woman presented with multiple uterine leiomyomas. The discovery was incidental, because the patient was asymptomatic. Macroscopically, a colloid-hemorrhagic-looking nodule was present. Histologic and immunohistochemical studies showed that this tumor was a small thyroid mass. Key words:,  相似文献   
10.
The receptor, c-kit, and its ligand, stem cell factor (SCF), are important regulators of ovarian follicle growth and development. The aim of this study was to identify the sites of expression of mRNA for c-kit and SCF in prepubertal and mature (pregnant and non-pregnant) animals. Ovaries were recovered from prepubertal animals, non-pregnant sows and five sows at approximately 3 months of gestation. Ovine SCF and c-kit DNA were cloned into plasmid vectors to produce RNA probes. Expression of mRNA encoding SCF and c-kit were detected via in situ hybridization. Both mRNA were detected throughout ovaries from all animals. This study provides evidence that the growth-factor complex is required throughout follicle development, and also for continued maintenance of the corpus luteum (CL) in the mature animal. SCF mRNA was localized to the granulosa cell layer and was also extensively expressed in endothelial tissue and throughout the CL. c-kit mRNA was detected in the theca layer, oocytes and also in CL. In conclusion, expression of SCF and c-kit mRNA in granulosa and theca cells, respectively, indicate an important interaction between somatic cells throughout follicle development and that in the mature animal, SCF and c-kit potentially have a role in maintaining progesterone secretion by the CL. The observations of continued expression of SCF and c-kit throughout development suggest that there may be differences in the role of this receptor-ligand complex between large mono- vs. poly ovulatory species, such as the pig.  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