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   30854篇
  免费   2803篇
  国内免费   52篇
耳鼻咽喉   244篇
儿科学   994篇
妇产科学   921篇
基础医学   4017篇
口腔科学   551篇
临床医学   3253篇
内科学   6655篇
皮肤病学   385篇
神经病学   2608篇
特种医学   971篇
外科学   4127篇
综合类   784篇
一般理论   48篇
预防医学   3705篇
眼科学   510篇
药学   2268篇
中国医学   71篇
肿瘤学   1597篇
  2023年   161篇
  2022年   179篇
  2021年   561篇
  2020年   335篇
  2019年   546篇
  2018年   734篇
  2017年   554篇
  2016年   496篇
  2015年   567篇
  2014年   769篇
  2013年   1150篇
  2012年   1619篇
  2011年   1842篇
  2010年   1005篇
  2009年   875篇
  2008年   1553篇
  2007年   1690篇
  2006年   1551篇
  2005年   1618篇
  2004年   1509篇
  2003年   1490篇
  2002年   1386篇
  2001年   877篇
  2000年   992篇
  1999年   801篇
  1998年   347篇
  1997年   266篇
  1996年   274篇
  1995年   254篇
  1994年   225篇
  1993年   202篇
  1992年   531篇
  1991年   556篇
  1990年   505篇
  1989年   475篇
  1988年   397篇
  1987年   422篇
  1986年   394篇
  1985年   372篇
  1984年   301篇
  1983年   251篇
  1982年   172篇
  1981年   169篇
  1979年   218篇
  1978年   172篇
  1977年   172篇
  1976年   147篇
  1974年   198篇
  1973年   176篇
  1972年   150篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
OBJECTIVE: To determine whether perinatal care in southwestern Ontario is regionalized, to identify trends over time in referral patterns, to quantify trends in perinatal death rates and to identify trends in perinatal death rates that give evidence of regionalization. DESIGN: Cohort study. SETTING: Thirty-two hospitals in southwestern Ontario (1 level III, 1 modified level III and 30 level II or I). PATIENTS: All pregnant women admitted to the hospitals and their infants. MAIN OUTCOME MEASURES: Antenatal and neonatal transfer status, live-born with discharge home alive from hospital of birth, stillborn, and live-born with death before discharge. RESULTS: Between 1982 and 1985 the antenatal transfer rate increased from 2.2% to 2.8% (p less than 0.003). The proportion of births of infants weighing 500 to 1499 g increased from 49% to 69% at the level III hospital. The neonatal transfer rate increased from 26.2% to 47.9% (p less than 0.05) for infants in this birth-weight category and decreased from 10.2% to 7.1% (p less than 0.03) for infants weighing 1500 to 2499 g. The death rate among infants of low birth weight was lowest among those born at the level III centre and decreased at all centres between 1982 and 1985. CONCLUSIONS: Perinatal care in southwestern Ontario is regionalized and not centralized; regionalization in southwestern Ontario increased between 1982 and 1985.  相似文献   
102.
Exposure of murine erythroleukemia cells (MELCs) to nicotinamide (NA) or its synthetic analog N′-methylnicotinamide (N′-MN) reduces cell growth and induces terminal differentiation, marked by increased heme and globin accumulation. On the contrary, 1-methylnicotinamide (1-MN), the primary metabolite of excess NA, was found to stimulate cell growth and reduce spontaneous differentiation of cultured MELCs. Log phase MELCs exhibited up to 50% higher cell density above untreated cells when cultured for up to 96 h with 2.5 mM 1-MN. When combined with NA or several chemically-unrelated inducers of hemoglobin synthesis in cultured MELCs, 1-MN reduced the globin mRNA levels and heme accumulation by 40–80%. 1-MN was able to inhibit heme production if present during only the first 24–48 h after NA exposure. Pre-treatment with 1-MN could not confer resistance of cells to effects of NA, suggesting the inhibition is reversible. Commitment to differentiate in semisolid medium by the most potent inducer, 5 mM N′-MN, was inhibited up to 95% by 2.5 mM concentrations of 1-MN. It appears that 1-MN has opposing effects on growth and induction of differentiation than those seen in MELC cultures exposed to NA or N′-MN.  相似文献   
103.
104.
We present a case of rapid failure of a total hip arthroplasty caused by infection with Haemophilus parainfluenzae. The septic loosening occurred over a period of 3 months and followed a dental extraction that had not been covered by prophylactic antibiotics. This failure occurred in a previously well-functioning and asymptomatic prosthetic joint.  相似文献   
105.
Described here is a case of meningitis caused by multidrug-resistant Acinetobacter baumannii susceptible only to colistin, which was treated successfully with intravenous colistin sulfomethate sodium (5 mg/kg/day). The levels of colistin in serum and cerebrospinal fluid and the pharmacokinetic/pharmacodynamic parameters of colistin were determined. In this case, intravenously administered colistin penetrated cerebrospinal fluid (25% of serum levels) at levels sustaining bactericidal concentrations. Electronic Publication  相似文献   
106.
Public knowledge about AIDS increasing   总被引:4,自引:0,他引:4  
In response to concern over the perceived limited effectiveness of Department of Health and Social Security (UK) advertising campaigns to inform the public of the basic facts of Acquired Immunodeficiency Syndrome (AIDS), a prospective questionnaire study was undertaken in Southampton, England to test the effectiveness of government education prior to a January, 1987 government television/leaflet advertising campaign. 300 questionnaires about AIDS were mailed in December of 1986 to a sample drawn from electoral rolls. The response rate was 61%. Most of the questions were drawn from material covered in the campaign. The results seemed to indicate a small overall increase in knowledge about AIDS. Some changes from a June survey were noted, e.g.: more people were aware that AIDS is a virus for which there is no cure and that it is not readily transmitted by sharing washing, eating or drinking utensils; more people believed that the statement that women are at greater risk for catching AIDS is false. Respondents were generally favorable to the government's continued use of television, even with explicit language, and to its use of the schools, for AIDS education. Many were not aware of the dangers to intravenous drug users or of the symptoms of AIDS. Other surveys have shown an increasing knowledge of AIDS dangers. It is possible that television coverage of the problem will continue to be necessary, in order that less literate populations be reached. Further AIDS health education in general is needed.  相似文献   
107.
108.
Sensory and motor task performance was assessed at 3 to 4 month intervals in chronically underfed and ad libitum-fed control rats from maturity into senescence. Diet-restricted rats weighed less than controls and lived significantly longer. Diminished body mass improved the underfed rats' abilities to hang suspended from a wire, to maintain balance on a narrow beam, and to descend from a wire mesh pole in a coordinated fashion. Underfed rats, however, lost these abilities at the same rate as did control rats. Undernutrition did not affect the startle response to acoustic stimulation, nor did it influence auditory or visual lead stimulus inhibition of the startle response. Both groups of animals showed progressive, age-related losses of sensory-motor function which proceeded at the same rate in each group. Life-prolonging undernutrition did not appear to retard aging of these simple, reflexive behaviors.  相似文献   
109.
One hundred patients who presented to the accident and emergency (A&E) department with an acute ankle sprain were entered into a study to determine the efficacy of topical ibuprofen cream by using a double-blind placebo controlled design in a single type of soft-tissue injury. The subjects were given either topical ibuprofen cream or a placebo cream in addition to the standard management of the department. Patients kept diaries recording walking ability and pain visual analogue scales for resting, standing and walking. A total of 51 patients returned diaries that were suitable for analysis. Patients using the topical ibuprofen cream had significant reduction in pain scores over the first 48 h of treatment.  相似文献   
110.
Reported are the results of a study of residents'' knowledge about malaria and antimalarial drugs and of their treatment-seeking behaviour in a rural area of western Kenya. The study subjects were generally well-informed about the symptoms of the disease. Malaria was perceived as a relatively mild illness, much less severe than acquired immunodeficiency syndrome (AIDS), measles, difficulty in breathing, and diarrhoea. Self-treatment was extremely common: of 138 episodes of febrile illness, 60% were treated at home with herbal remedies or medicines purchased at local shops, and only 18% received treatment at a health centre or hospital; no treatment was sought by the remainder. Commercially available chloroquine preparations were perceived as more effective than either antipyretics or herbal remedies for the treatment of malaria, and injections were regarded as more effective than oral medications. 4-Amino-quinolines were used to treat 58% of febrile illnesses but in only 12% of the cases was a curative dose of > or = 25 mg/kg body weight employed. Even attendance at a health centre did not ensure adequate treatment because of the common practice of sharing medication among family members. Greatly increased attention should be paid to the role of home treatment of malaria when policies are being developed for the management of febrile illnesses in sub-Saharan Africa.  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