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   1407654篇
  免费   115752篇
  国内免费   3328篇
耳鼻咽喉   18366篇
儿科学   46565篇
妇产科学   41046篇
基础医学   200761篇
口腔科学   37687篇
临床医学   125862篇
内科学   284089篇
皮肤病学   33359篇
神经病学   116802篇
特种医学   53827篇
外国民族医学   464篇
外科学   210472篇
综合类   32738篇
现状与发展   3篇
一般理论   488篇
预防医学   109884篇
眼科学   31445篇
药学   98476篇
  1篇
中国医学   3347篇
肿瘤学   81052篇
  2021年   10849篇
  2019年   11667篇
  2018年   16572篇
  2017年   12677篇
  2016年   14262篇
  2015年   16016篇
  2014年   22564篇
  2013年   33397篇
  2012年   45404篇
  2011年   47942篇
  2010年   28160篇
  2009年   27060篇
  2008年   44328篇
  2007年   46833篇
  2006年   47398篇
  2005年   45865篇
  2004年   43763篇
  2003年   41708篇
  2002年   40209篇
  2001年   73018篇
  2000年   74533篇
  1999年   61570篇
  1998年   16996篇
  1997年   15435篇
  1996年   15585篇
  1995年   14792篇
  1994年   13406篇
  1993年   12590篇
  1992年   45858篇
  1991年   43490篇
  1990年   41503篇
  1989年   39565篇
  1988年   36197篇
  1987年   35369篇
  1986年   32876篇
  1985年   31292篇
  1984年   23834篇
  1983年   20033篇
  1982年   12215篇
  1981年   10780篇
  1979年   20702篇
  1978年   14576篇
  1977年   12084篇
  1976年   11365篇
  1975年   11619篇
  1974年   13988篇
  1973年   13534篇
  1972年   12633篇
  1971年   11469篇
  1970年   10911篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
961.
Effects of a photoreceptor-specific biotoxin, tunicamycin (TM), injected intravitreally into the goldfish eye at one side, were explored on electroretinograms (ERGs) and proliferating cell nuclear antigen-immunoreactive (PCNA-ir) nuclei, representing the mitotic activity of rod precursors, in the retina at both sides. The eye-cup preparations were made for ERG recording, and the retinas were isolated and processed as cryosections or wholemounts by a routine immunohistochemical method for visinin (cones), opsin (rods), tyrosine hydroxylase (dopaminergic cells) and proliferating cell nuclear antigen (PCNA), at various intervals after intravitreal injection with TM (1.0 micrograms/eye). On some thin sections, autoradiographic study was combined following intravitreal injection with [3H]thymidine (TdR, 0.1 microCi/eye). The dose of TM used heavily destroyed cones and rods only in the treated retinas 2-15 days after injection, the photoreceptors being renewed for further 15-20 days. Approximately in parallel, ERGs were largely impaired 2-10 days after TM injection and recovered for 10-20 days. However, intravitreal TM altered the distribution and density of PCNA-ir nuclei in both treated and untreated retinas. The density of PCNA-ir nuclei reduced at first (on days 1 and 2), and then clustered and rapidly increased on days 3-5 and maintained at high levels with diffuse distribution over the whole area, particularly in the treated retinas, up to 60 days after TM injection; the maximum peak of 3.7 and 20 times the initial level was seen on day 20 in the outer nuclear layer (ONL) and inner nuclear layer (INL), respectively. PCNA-ir nuclei were found to be abundant in the ONL even after the photoreceptors and ERGs had been restored in the treated retinas on day 20, suggesting a kind of overproduction of retinal cells. The autoradiographic study provided comparable results to those obtained with PCNA immunohistochemistry. The mechanism by which damage to the treated retina causes rod precursor cells to proliferate in the untreated retina remains unresolved.  相似文献   
962.
Although general suggestions have been made regarding a radiology residency curriculum, no specific list of entities has been offered. Over the past ten years, we have developed a resident-run morning conference in musculoskeletal radiology that is supervised by faculty and covers a specific curriculum. We offer our curriculum as an example that may assist other departments in developing their own curricula.  相似文献   
963.
Lumbar subarachnoid catheterization in rats   总被引:3,自引:0,他引:3  
An animal model was developed for the study of subarachnoid (spinal) anesthesia and analgesia under unanesthetized, unsedated and unrestrained conditions. Sprague-Dawley rats were anesthetized with intraperitoneal ketamine (75-100 mg.kg-1). A PE10 catheter was inserted under direct vision into the lumbar subarachnoid space, through partial laminectomy of L1 or L2 with or without removal of adjacent intervertebral ligament. One week after surgery, correct position of the catheter was verified by subarachnoid injection of 0.03-0.05 ml of 1.5% lidocaine, which produced temporary hind limb paralysis in all but one animal in 28 consecutive operations. There was neither mortality nor major complication, intraoperatively or postoperatively. Only 2 animals developed minor subcutaneous would infections which responded to incision, drainage and debridement.  相似文献   
964.
Sixty drinking water samples collected from various sources in different areas of Delhi during epidemic of cholera and gastroenteritis were analysed for bacteriological standards. Only 27 (45 per cent) samples were found to be satisfactory for human consumption. Remaining thirty-three (55 per cent) samples showed presence of coliform organisms with MPN value ranging from 10 to 1800+ per 100 ml. Among these positive samples, 31 (93.9 per cent) samples contained faecal coli. Twenty out of thirty (66.6 per cent) Hand pump, 9 out of 21 (42.8 per cent) Taps 2 out of 4 (50 per cent) Tube well and 2 out of 5 (40 per cent) of miscellaneous sources showed contamination with coliform organisms.  相似文献   
965.
966.
967.
968.
969.
We carried out a nonrandomized, unblinded study to compare the efficacy of rifampin alone with that of rifampin in combination with trimethoprim in the eradication of the Haemophilus influenzae type b (HIB) carrier state among contacts of patients with invasive HIB infection. The study population comprised 17 index patients admitted to hospital with severe HIB infections and 233 contacts, 43 of whom had nasopharyngeal colonization with HIB of the same biotype as that of the index patient. Rifampin in a daily dose of 20 mg/kg (maximum 600 mg) for 4 days eradicated the carrier state in 86% of cases, as did the combination of rifampin at the same dosage and trimethoprim in a daily dose of 5 mg/kg (maximum 160 mg) for 4 days.  相似文献   
970.
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