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   2986篇
  免费   170篇
  国内免费   2篇
耳鼻咽喉   50篇
儿科学   125篇
妇产科学   85篇
基础医学   426篇
口腔科学   26篇
临床医学   229篇
内科学   492篇
皮肤病学   64篇
神经病学   108篇
特种医学   47篇
外科学   307篇
综合类   207篇
一般理论   4篇
预防医学   212篇
眼科学   354篇
药学   184篇
中国医学   15篇
肿瘤学   223篇
  2023年   14篇
  2022年   49篇
  2021年   103篇
  2020年   70篇
  2019年   53篇
  2018年   77篇
  2017年   40篇
  2016年   63篇
  2015年   84篇
  2014年   105篇
  2013年   144篇
  2012年   191篇
  2011年   193篇
  2010年   128篇
  2009年   79篇
  2008年   165篇
  2007年   163篇
  2006年   125篇
  2005年   131篇
  2004年   140篇
  2003年   148篇
  2002年   130篇
  2001年   89篇
  2000年   102篇
  1999年   85篇
  1998年   35篇
  1997年   16篇
  1996年   19篇
  1995年   19篇
  1994年   21篇
  1993年   11篇
  1992年   27篇
  1991年   31篇
  1990年   32篇
  1989年   20篇
  1988年   24篇
  1987年   17篇
  1986年   15篇
  1985年   14篇
  1984年   11篇
  1981年   14篇
  1980年   10篇
  1978年   8篇
  1977年   11篇
  1976年   10篇
  1975年   11篇
  1973年   11篇
  1972年   9篇
  1970年   8篇
  1968年   11篇
排序方式: 共有3158条查询结果,搜索用时 125 毫秒
161.
162.
163.
Soft tubing Norplant(R) contraceptive implants were studied in 1210 women for 7 years to measure the duration of effectiveness and the magnitude of the pregnancy rates over that time. Mean age at enrollment was 27.4 years. Of the enrollees, 42% were US residents. One-sixth (16.1%) weighed >/=70 kg at the time of implant placement. At the end of 5 years, the cumulative pregnancy rate was 1.1/100; at the end of 7 years, it was 1.9/100. No pregnancies occurred to any of the 400 women who enrolled in the study at age >/=30 years and who weighed <100 kg. Among women aged 18-33 years, the 7-year Norplant pregnancy rates are comparable to the median pregnancy rates of tubal sterilization methods for women of the same age and duration of use. For women aged >/=34 years, without regard to weight at admission, the 7-year effectiveness of soft tubing Norplant equals or surpasses that of tubal sterilization. For continuing implant users, annual pregnancy rates <1.0/100 in years 6 and 7, together with low cumulative pregnancy rates, testify that Norplant capsule implants remain highly effective for 7 years.  相似文献   
164.
Summary: This study was conducted to evaluate the role of the Amniotic Fluid Index (AFI), used along with nonstress cardiotocography (NST) and fetal acoustic stimulation test (FAST), when required, in prediction of adverse pregnancy outcome. Over a 3-year period 565 pregnant women had antepartum fetal surveillance due to various high risk pregnancy factors and delivered within 7 days of the test. Antepartum fetal surveillance included nonstress cardiotocography together with estimation of AFI. Need for induction of labour, presence of meconium at rupture of membranes, Caesarean section for fetal distress, Apgar score at 5 minutes, need for neonatal endotracheal intubation, admission to neonatal special care unit and perinatal death were the main outcome measures.
Nonreactive nonstress tests and Caesarean sections for fetal distress were more common and neonatal outcome was significantly poorer in patients with AFI < 5 cm than in those with higher AFI values. Of the 4 perinatal deaths in the group with AFI < 5 cm, 3 had a reactive NST within 7 days of fetal death.
It is concluded that pregnancy outcome is often poor in the presence of very low AFI and in these cases a reactive NST loses its usual reassuring value. It is suggested that AFI estimation should be included as an integral part of antepartum fetal surveillance of high risk pregnancies.  相似文献   
165.
Human lung tumor cells (ChaGo) established in culture from a bronchogenic squamous cell carcinoma synthesize and secrete large amounts of human chorionic gonadotropin (HCG), predominantly the alpha subunit of the glycoprotein hormone. ChaGo cells lose their transformation phenotypes following treatment with anti-alpha-HCG antibody or following inhibition of intracellular synthesis of alpha-HCG by the anti-sense RNA technique. We report that tumors induced by ChaGo cells in female athymic mice undergo necrotic degeneration following local or intraperitoneal administration of alpha-HCG-specific-antibody. The alpha-HCG antibody did not affect the growth of tumor induced by alpha-HCG nonproducing human tumor cells. Histopathological examinations of the anti-alpha-HCG antibody-treated tumor tissues showed active necrosis. When the antibody treatment was discontinued, the tumorigenesis process resumed. When anti-alpha-HCG antibody was administered simultaneously with ChaGo cells, a concentration-dependent inhibition of tumor growth in athymic mice was completely prevented at higher concentrations of the specific antibody.  相似文献   
166.
167.
Hepatitis B surface antigen screening was performed on non-Oriental patients with the diagnosis of acute salpingitis. Six of 59 (10.17%) had hepatitis B surface antigenemia. We therefore recommend hepatitis B screening for all patients with salpingitis. The detection of covert hepatitis B helps to protect hospital staff and provides important information for the patient. Further, the administration of hepatitis B vaccine may be appropriate for those patients with acute salpingitis who are found to be hepatitis B surface antigen-negative.  相似文献   
168.
A new approach in cultivation of Mycobacterium leprae in thyroxine treated Lowenstein-Jensen media is reported. The method has been proved to be successful as the organisms multiplied and remained viable in the thyroxine solution added at the bottom of the culture vial, for a period of 18 to 20 weeks of incubation at 37 degrees C. This has been possible due to metabolic stimulating action of thyroxine sodium solution as well as diffusion of nutrients into this solution from the medium. Intracutaneous inoculation of culture fluid on the surface of foot pad in cortisone treated mouse helped in rapid appearance of the specific lesion at the site within 20 days after injection. Both the intracutaneous method of inoculation and treatment of mouse with high doses of cortisone may play some role in shortening the period of development of such lesion.  相似文献   
169.
170.
Adult male rats were given injections of oestradiol-17 beta (50 micrograms/100 g body wt per day) for 7 days. When they were killed 14 days after the last injection, serum levels of gonadotrophins and testosterone and weights of accessory sex organs were less, testicular 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity was suppressed and spermatogenesis was inhibited. Administration of alpha 2u-globulin (1.5 mg/day) for 14 days to oestrogen-treated rats and for 10 days to control rats resulted in increased concentrations of gonadotrophins and testosterone in the serum. Accessory sex organ weight and spermatogenesis appeared to be normal while 17 beta-HSD activity increased in oestrogen-treated rats after treatment with alpha 2u-globulin. It was concluded that alpha 2u-globulin has an effect on testicular function in oestrogenized rats by inducing gonadotrophin and testosterone synthesis.  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