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   2264509篇
  免费   168696篇
  国内免费   7405篇
耳鼻咽喉   30370篇
儿科学   72408篇
妇产科学   60946篇
基础医学   314732篇
口腔科学   63634篇
临床医学   203739篇
内科学   448173篇
皮肤病学   53212篇
神经病学   181686篇
特种医学   92299篇
外国民族医学   472篇
外科学   349072篇
综合类   49512篇
现状与发展   3篇
一般理论   686篇
预防医学   171726篇
眼科学   49738篇
药学   167979篇
  10篇
中国医学   4585篇
肿瘤学   125628篇
  2018年   23410篇
  2017年   18614篇
  2016年   22001篇
  2015年   24135篇
  2014年   33182篇
  2013年   49752篇
  2012年   63467篇
  2011年   68088篇
  2010年   41297篇
  2009年   39331篇
  2008年   63646篇
  2007年   67938篇
  2006年   69209篇
  2005年   66411篇
  2004年   63624篇
  2003年   61834篇
  2002年   59324篇
  2001年   113817篇
  2000年   117527篇
  1999年   97588篇
  1998年   27199篇
  1997年   24211篇
  1996年   24887篇
  1995年   24446篇
  1994年   22629篇
  1993年   21334篇
  1992年   77343篇
  1991年   74963篇
  1990年   72768篇
  1989年   69913篇
  1988年   64029篇
  1987年   62747篇
  1986年   59167篇
  1985年   56603篇
  1984年   42283篇
  1983年   35556篇
  1982年   21232篇
  1981年   18801篇
  1980年   17785篇
  1979年   37975篇
  1978年   26714篇
  1977年   23128篇
  1976年   20789篇
  1975年   22424篇
  1974年   26198篇
  1973年   25202篇
  1972年   23547篇
  1971年   21890篇
  1970年   20054篇
  1969年   19047篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
The effects of different amounts of dietary zinc on the Zn absorption rate and on Zn, calcium and magnesium concentrations in tissues of MOPC 104E tumor-bearing Balb/c mice were determined. The Zn absorption rate was inversely related to the amounts of Zn in their diets and was lower than that of nontumor-bearing control mice fed a laboratory mice chow. Zn concentrations of tumor-bearing mice were also low compared with control mice but tumor Zn concentrations, regardless of the concentrations of Zn in the diets, were higher than those of normal tissues of the host other than the pancreas. Ca concentrations in tumor and tissues of tumor-bearing mice were higher than in control animals but Mg concentrations in tissues of tumor-bearing mice appeared to be similar to those of control mice. Results suggest that tumor-bearing mice have a lower intestinal Zn absorption capacity and a higher Zn uptake rate causing other tissues to become hypozincemic and hypercalcemic.  相似文献   
962.
963.
Dihydroxyacetone (DHA), a browning agent, protects photosensitive rats and humans against long ultraviolet radiation (UVA, 320-400 nm) and visible (blue) light. The photoprotective efficacy of DHA and structurally similar compounds was assessed as prevention of edema in the paws of psoralen-sensitized rats, after exposure to blacklight fluorescent lamps. Methylglyoxal produced a yellow-brown color and provided nearly the same protection as DHA, whereas monohydroxyacetone did not color the skin and afforded little or no protection. Glyceraldehyde provided a moderate amount of protection, which was enhanced by prior exposure of the agent to alkaline pH. A solution of 5-hydroxymethylfurfuraldehyde was yellow and provided minimal protection by staining the skin rather than browning it. We conclude that the ability to produce a brown color in skin is a useful criterion for screening compounds for photoprotective efficacy against UVA radiation.  相似文献   
964.
A clinical phase I study for T-2588 was carried out in 25 healthy male volunteers. Each volunteer received T-2588 in one of the following doses: 100 mg capsule or tablet as a single oral administration in fasting or non-fasting state, 200 or 400 mg capsule as a single oral administration in non-fasting state or 300 or 600 mg daily for 14 approximately 15 days as a repeated administration in non-fasting state. The results are summarized below. No subjective or objective adverse effects were noted after a single oral administration. But repeated dose of 300 mg daily for 15 days and 600 mg daily for 14 days brought about abdominal distension in 1 case and soft stool in 1 case, respectively. As an abnormal change in clinical laboratory findings, 1 case with slight increase in transaminase after a single administration and 3 cases with slight increases in transaminase after repeated doses were observed. Time to reach a maximum concentration of T-2525 in blood (Tmax) was longer in subjects at non-fasting states than subjects in fasting states. Maximum blood concentration was lower in the latter than in the former. Urinary excretion rate in 8 hours after an oral administration was 19 approximately 28% and it was higher in non-fasting subject than in fasting subject. No accumulation of T-2588 was noted after repeated doses.  相似文献   
965.
966.
A 50-year-old woman with bilateral inflammatory breast cancer (T4, N1b, M1, Stage IV) underwent right extended radical mastectomy and left modified radical mastectomy following pre-operative administration of carcinostatics (ADM, 5-FU) and irradiation. However, tumor recurrence was observed at the skin and right pleural cavity after the operation. Adriamycin-containing combination chemotherapy and radiation therapy were performed, but no significant response was obtained. CDDP was then administered intravenously at a daily dose of 62.5 mg/m2 at intervals of 60 days. The pleural effusion disappeared and the extent of skin metastasis was reduced, resulting in partial response which lasted for 90 days. The serum CEA level decreased from 13.1 ng/ml to 2.3 ng/ml. As the side effects of this therapy, slight nausea, vomiting and general fatigue were observed. This result suggested that CDDP is an effective drug for inflammatory breast cancer.  相似文献   
967.
Platelet antibodies in systemic lupus erythematosus   总被引:2,自引:0,他引:2  
In systemic lupus erythematosus (SLE), the precise cause of the thrombocytopenia is unknown. Since platelet associated IgG is increased in many patients, it has been suggested that the destruction of platelets might be dependent on specific antibodies. In nine patients with SLE, platelet associated immunoglobulins were found together with free serum antibody which bound to platelets from all normal subjects. Using an immunoblotting technique with membrane proteins from normal platelets incubated with patient sera, target antigens were localized on a band of mol wt 108,000 in two cases (B. and N.) and on a band of mol wt 66,000 in a third (M.). When the same technique was applied to autologous platelets of patient N., autoantibody binding to the protein of mol wt 108,000 was demonstrated. The antigenic determinants were not removed from the platelets by enzyme treatment or by disulphide bond reduction, and were localized in the cytoplasmic fraction of the platelets.  相似文献   
968.
969.
This research was designed to test the extent to which health education and health services administration students' perceptions of their roles as professionals matched the expectations of professional faculty. These perceptions were found to match in general. However, doubt was cast on the extent to which internships or practicums contributed to this result, since there was no change in student responses between the beginning of the junior year and end of the senior year, a period which includes fieldwork and most of the professional coursework presumed to influence professional development. Additional research is required to test this result with other student populations in other health professions and identify the point at which professional role and task definitions are amenable to change.  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