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   91055篇
  免费   5911篇
  国内免费   1487篇
耳鼻咽喉   1494篇
儿科学   1224篇
妇产科学   1549篇
基础医学   14366篇
口腔科学   1919篇
临床医学   8409篇
内科学   17760篇
皮肤病学   2717篇
神经病学   6287篇
特种医学   4549篇
外国民族医学   4篇
外科学   11982篇
综合类   2170篇
现状与发展   1篇
一般理论   32篇
预防医学   4664篇
眼科学   2204篇
药学   8155篇
  7篇
中国医学   1475篇
肿瘤学   7485篇
  2023年   775篇
  2022年   2267篇
  2021年   3482篇
  2020年   1841篇
  2019年   2323篇
  2018年   2754篇
  2017年   2110篇
  2016年   2723篇
  2015年   3884篇
  2014年   4693篇
  2013年   5337篇
  2012年   8002篇
  2011年   7554篇
  2010年   4455篇
  2009年   3805篇
  2008年   5436篇
  2007年   4974篇
  2006年   4401篇
  2005年   3987篇
  2004年   3343篇
  2003年   2965篇
  2002年   2605篇
  2001年   2161篇
  2000年   1988篇
  1999年   1598篇
  1998年   639篇
  1997年   518篇
  1996年   425篇
  1995年   372篇
  1994年   326篇
  1993年   247篇
  1992年   651篇
  1991年   561篇
  1990年   557篇
  1989年   524篇
  1988年   501篇
  1987年   454篇
  1986年   362篇
  1985年   330篇
  1984年   267篇
  1983年   224篇
  1982年   135篇
  1981年   132篇
  1980年   111篇
  1979年   207篇
  1978年   155篇
  1977年   105篇
  1975年   110篇
  1974年   116篇
  1972年   100篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
In these studies, the physical dependence liability of butorphanol, a mixed 'agonist/antagonist' opioid analgesic, was compared to that of morphine. Male, Sprague-Dawley rats received i.c.v. infusions of saline (1 microliter/h), or an equimolar dose of butorphanol or morphine (52.3 nmol/h) for 3 days. The physical dependence liabilities of these two compounds were then compared by assessing both behavioral withdrawal signs and weight loss following naloxone-precipitated withdrawal. Body weight loss was also evaluated following abrupt (cessation of infusion) withdrawal from butorphanol or morphine. In animals receiving i.c.v. infusions of butorphanol or morphine, naloxone administration (5 mg/kg s.c.) induced an equivalent degree of body weight loss compared to saline-treated animals. In addition, the ED50 of naloxone to produce wet shakes, escape behavior, teeth chattering, urination and defecation was equivalent in rats receiving butorphanol or morphine. Infusions of butorphanol or morphine also produced an equivalent degree of weight loss in animals undergoing abrupt withdrawal. These results demonstrate then that a substantial degree of physical dependence had developed in rats which received a large dose of butorphanol.  相似文献   
53.
The changes in mechanical properties and free radical concentration of curing Simplex P Radiopaque Bone Cement in vivo and in vitro conditions were studied. Samples were prepared so that each in vivo sample that cured and aged in the canine femoral intramedullary cavities had an in vitro counterpart that was cured and aged in a constant-temperature saline bath at 37 degrees C. An electron paramagnetic resonance (EPR) spectrometer was used to measure the growth and decay (curing) of polymerization radicals. The results of EPR measurements showed that the curing (disappearance of free radicals) of in vivo samples takes a much longer time (more than 4 weeks) than in vitro curing (less than 2 weeks). The mechanical tests indicate that, whether aged in vivo or in vitro, the strength increased rapidly for the first 1-2 weeks and then slight increases were seen for up to 6 months.  相似文献   
54.
The effects of haloperidol on motor and functioning and cognitive functioning were studied in young (3-5 months old) and aged (20-22 months old) male mice by examining haloperidol-induced catalepsy and haloperidol-induced decrements in performance on a radial arm maze. The aged mice were much more sensitive to these adverse effects of haloperidol than were the young mice. Studies of the distribution of radioactivity from [3H]haloperidol to the brain indicated that the differences in sensitivity to this drug were not due to pharmacokinetic differences. The results demonstrate that mice are suitable for studies of aging-induced changes in the behavioral effects of neuroleptic agents.  相似文献   
55.
H Z Park  S P Lee  A L Schy 《Gastroenterology》1991,100(6):1665-1670
Ceftriaxone, a third-generation cephalosporin, is partially excreted into bile. With its clinical use, the formation of gallbladder sludge detected by ultrasonography has been reported. Four surgical specimens were examined and no gallstones were found. Instead, fine precipitates of 20-250 microns were present. Microscopically, there was a small number of cholesterol monohydrate crystals and bilirubin granules among an abundant amount of granular-crystalline material that was not morphologically cholesterol monohydrate crystals. The chemical composition of the precipitates (n = 4) was determined. There was a small amount of cholesterol (1.7% +/- 0.8%) and bilirubin (13.9% +/- 0.74%). The major component of the precipitate was a residue. On further analysis using thin-layer chromatography, high-performance liquid chromatography, and electron microprobe analysis, the residue was identified as a calcium salt of ceftriaxone. The residue also had identical crystal morphology and chromatographic elution profile as authentic calcium-ceftriaxone standards. It is concluded that ceftriaxone, after excretion and being concentrated in the gallbladder bile, can form a precipitate. The major constituent has been identified as a ceftriaxone-calcium salt.  相似文献   
56.
57.
Immunoscintigraphy with radiolabelled monoclonal antibodies is widely used to detect solid tumours, but only a few trials have been carried out concerning the specific in vivo localization of an inflammatory process. The purpose of this study was to investigate the detectability of tuberculous foci utilizing this method with radiolabelled bacillus Calmette-Guérin (BCG)-specific F(ab')2 in rabbits. All of the tuberculous lesions (n = 8) were clearly visualized on serial scintigraphy for up to 48 h after injection of the antibody. Immunohistochemical and Ziel-Neelson staining of the tuberculous lesions confirmed the presence of the tuberculous antigens and bacilli. It failed to demonstrate any sustained retention of the BCG-specific antibody fragment in the control group with syphilitic orchitis (n = 2). Therefore, the specific in vivo localization of tuberculosis is feasible by immunoscintigraphy.  相似文献   
58.
This is the first preliminary report among two consecutive papers. Partial mastectomy(PM), axillary lymph node dissection(AD) and radiotherapy (RT) were performed on seventeen operable breast cancer patients who had been admitted from April 1991 to March 1992 to the department of surgery, Yongdong Severance Hospital for improved cosmetic appearance and better survival rate. Of seventeen patients, 47% were T1 lesion and 76% were stage I and II. Extensive intraductal component(EIC) within or around the tumor was also analyzed. Twenty nine per cent of the patients were EIC positive. The mean number of axillary lymph nodes was 21.5 after PM with AD and 20.5 after mastectomy. For radiotherapy, 4,500 rad was delivered to the breast parenchyma and 1,600 rad of boost to the primary tumor site using the electron beam method after surgery. All patients have since been living well without any local recurrence and were satisfied with breast preservation for the one-year follow-up period. We concluded that the PM, AD and RT can be another surgical treatment modality of breast cancer. A longer follow-up data will be followed on the second paper.  相似文献   
59.
60.
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