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   12855篇
  免费   1224篇
  国内免费   20篇
耳鼻咽喉   109篇
儿科学   561篇
妇产科学   339篇
基础医学   1780篇
口腔科学   409篇
临床医学   1378篇
内科学   2642篇
皮肤病学   198篇
神经病学   1006篇
特种医学   659篇
外科学   1569篇
综合类   362篇
一般理论   19篇
预防医学   1373篇
眼科学   120篇
药学   933篇
中国医学   34篇
肿瘤学   608篇
  2021年   200篇
  2020年   90篇
  2019年   178篇
  2018年   256篇
  2017年   154篇
  2016年   197篇
  2015年   226篇
  2014年   300篇
  2013年   443篇
  2012年   649篇
  2011年   604篇
  2010年   367篇
  2009年   393篇
  2008年   577篇
  2007年   604篇
  2006年   544篇
  2005年   518篇
  2004年   480篇
  2003年   436篇
  2002年   434篇
  2001年   409篇
  2000年   414篇
  1999年   364篇
  1998年   210篇
  1997年   183篇
  1996年   157篇
  1995年   134篇
  1994年   156篇
  1993年   139篇
  1992年   296篇
  1991年   277篇
  1990年   268篇
  1989年   288篇
  1988年   262篇
  1987年   260篇
  1986年   251篇
  1985年   204篇
  1984年   166篇
  1983年   171篇
  1982年   101篇
  1981年   97篇
  1980年   93篇
  1979年   174篇
  1978年   132篇
  1977年   120篇
  1976年   88篇
  1975年   101篇
  1974年   103篇
  1973年   91篇
  1972年   77篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Two human parathyroid hormone-related protein (hPTHrP) fragments were tested for effects on maternofetal transfer of 45Ca and Mg across the in-situ perfused rat placenta at 21 days of gestation (term = 23 days). The fetal placental circulation was perfused with a Mg-free Krebs-Ringer solution and the unidirectional maternofetal clearance (Kmf) of 45Ca and Mg compared with that of 51Cr-EDTA, the latter being employed as a paracellular diffusional marker. Placental perfusion with hPTHrP(1-34) (100 ng/ml) or hPTHrP(75-86)amide (50 ng/ml) did not significantly alter the Kmf of 45Ca or that of Mg. In separate rats, however, hPTHrP(1-34) but not hPTHrP(75-86)amide stimulated marked placental cyclic AMP (cAMP) release, the peak response of 63 +/- 7 pmol/min occurring 10 min after the beginning of the peptide perfusion. A lower dose of hPTHrP(1-34) (4 ng/ml) produced a similar peak release of cAMP, as did [Nle8,21, Tyr34]-rPTH(1-34)amide (4 ng/ml) and the adenylate cyclase agonist forskolin (17 mumol/l). Forskolin also rapidly increased the Kmf of 45Ca but not that of Mg or 51Cr-EDTA. The present study indicates that hPTHrP does not acutely affect maternofetal transfer of Ca or Mg across the perfused rat placenta. The data also question the role played by cAMP in the stimulatory actions of forskolin on placental Ca transport.  相似文献   
32.
A toxicologic-pathologic study of isobutyl-2-cyanoacrylate (Bucrylate) was carried out first in dogs and then in humans whose arteriovenous malformations were infused with this embolic agent. The canine specimens obtained at 7, 18, 28, and 147 days after embolization showed the development of a mild histiocytic giant cell reaction, which evolved to end-state sclerotic arteritis. The response was confined to the vessels and did not involve contiguous parenchymal tissues. Ten human specimens, obtained from 1 hr to 7 years after treatment, showed a similar bland reaction with no evidence of suppuration or premalignant changes.  相似文献   
33.
A study was made of the pattern of distribution of mercury in the tissues of some plant species collected around a chlor-alkali factory in India. Different plants accumulated different levels of mercury in their tissues. Accumulation in leaves was the highest, followed by the stem and the root and, in some cases, the root and the stem. A significant correlation was noted between the mercury concentration of the soil and the plant tissues and between different tissues. Grazers (goats, sheep) also accumulated significant levels of mercury in their tissues.  相似文献   
34.
Reproductive and social histories of the first 100 patients attending the in vitro fertilisation (IVF) programme at National Women's Hospital, Auckland, have been studied. The average age at first treatment was 31.6 (SD 3.9) for women, and 34.2 (4.6) for men. The couples had been married 7.6 (3.3) years and had experienced 6.7 (3.2) years infertility. It was a second marriage for 16. The husbands had on average a higher social classing than the population (class: number [population]--1:16 (7%), 2:18 (14%), 3:42 (28%), 4:19 (29%), 5:4 (14%), 6:1 (8%); but this bias diminished in the next 159 couples. Nine couples withdrew before their quota of cycles, 7 from stress. Tubal disease was the cause of infertility in 93, but in 69 its origin was untraceable. In 22 it could be attributed to pelvic inflammatory disease (eight associated with IUCDs and 2 with sexually transmitted disease) and in two to sterilisation. Although 59 women had a history of having conceived, only 34 were parous, and only 11 had a child of the current union.  相似文献   
35.
Submersion injuries are a major cause of morbidity and mortality in children and young adults. The Emergency Department physician should be familiar with the epidemiology, pathophysiology, modes of therapy, and prognostic indicators in order to provide optimum resuscitation to the near-drowning victim, correct referral, and counseling to their families.  相似文献   
36.
37.
38.
39.
Retrorenal colon: implications for percutaneous diskectomy   总被引:1,自引:0,他引:1  
Helms  CA; Munk  PL; Witt  WS; Davis  GW; Morris  J; Onik  G 《Radiology》1989,171(3):864-865
It has been recommended that computed tomography (CT) with the patient prone be performed in every patient undergoing percutaneous diskectomy; this would enable detection of a retrorenal location of the colon, which could interfere with the percutaneous procedure. In this evaluation of 346 prone CT studies, only one patient (0.29%) was found to have retrorenal or retropsoas bowel that would have been perforated at diskectomy. Because of this extremely low prevalence, the performance of prone CT in every patient undergoing percutaneous lumbar diskectomy is not believed to be necessary.  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