全文获取类型
收费全文 | 19214篇 |
免费 | 1767篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 151篇 |
儿科学 | 552篇 |
妇产科学 | 354篇 |
基础医学 | 2822篇 |
口腔科学 | 414篇 |
临床医学 | 2233篇 |
内科学 | 4058篇 |
皮肤病学 | 453篇 |
神经病学 | 1467篇 |
特种医学 | 887篇 |
外科学 | 3123篇 |
综合类 | 440篇 |
一般理论 | 10篇 |
预防医学 | 1589篇 |
眼科学 | 256篇 |
药学 | 1263篇 |
1篇 | |
中国医学 | 10篇 |
肿瘤学 | 935篇 |
出版年
2021年 | 224篇 |
2020年 | 172篇 |
2019年 | 263篇 |
2018年 | 252篇 |
2017年 | 247篇 |
2016年 | 260篇 |
2015年 | 280篇 |
2014年 | 407篇 |
2013年 | 566篇 |
2012年 | 878篇 |
2011年 | 828篇 |
2010年 | 463篇 |
2009年 | 492篇 |
2008年 | 759篇 |
2007年 | 837篇 |
2006年 | 818篇 |
2005年 | 820篇 |
2004年 | 757篇 |
2003年 | 729篇 |
2002年 | 667篇 |
2001年 | 574篇 |
2000年 | 672篇 |
1999年 | 545篇 |
1998年 | 306篇 |
1997年 | 285篇 |
1996年 | 274篇 |
1995年 | 226篇 |
1994年 | 196篇 |
1993年 | 224篇 |
1992年 | 491篇 |
1991年 | 473篇 |
1990年 | 426篇 |
1989年 | 450篇 |
1988年 | 430篇 |
1987年 | 411篇 |
1986年 | 408篇 |
1985年 | 390篇 |
1984年 | 353篇 |
1983年 | 252篇 |
1982年 | 169篇 |
1981年 | 172篇 |
1980年 | 168篇 |
1979年 | 265篇 |
1978年 | 178篇 |
1977年 | 148篇 |
1976年 | 156篇 |
1975年 | 135篇 |
1974年 | 166篇 |
1973年 | 163篇 |
1972年 | 157篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Four clinical trials of porcine islet transplantation have been reported, and there are verbal reports that clinical trials on much larger scales are continuing in centers in China and Russia. The four reported trials are briefly reviewed and, in the light of the present status of experimental islet xenotransplantation, consideration is given to whether such trials are currently justified. The Ethics Committee of the International Xenotransplantation Association has (1) emphasized the need for encouraging studies in non-human primates before clinical trials should be undertaken, (2) mandatory monitoring for the transfer of porcine microorganisms, and (3) careful regulation and oversight by recognized bodies. Other aspects of the topic, such as the need for informed consent, are briefly discussed. We conclude that, at the present time, more data documenting convincing efficacy, focused on clinically applicable immunosuppressive regimens, are needed to justify the initiation of closely monitored clinical trials. A clinical trial may then be justified even though the potential risk to the patients, and possibly for society, will not be zero. 相似文献
2.
3.
L C Harlan B F Polk S Cooper T P Blaszkowski J Ignatius-Smith M Stromer H Mull 《American journal of preventive medicine》1986,2(5):256-261
The effects of labeling a person as hypertensive have important implications for hypertension screening. The Hypertension Detection and Follow-up Program (HDFP) provides an opportunity to examine the effects of labeling, treatment, and study assignment on a large group of hypertensives (n = 10,070). Their answers to questions regarding perceived health and general well-being asked at baseline and again one year later were analyzed. There was no significant change in the perceived health status of persons who were unaware of their hypertension at baseline and remained untreated at one year (labeling alone). The effect of labeling plus treatment was associated with a significant decrease in perceived health. The effect of antihypertensive drug therapy on perceived health status was examined in persons who were aware of their hypertension but not on treatment at baseline, and on treatment at one year. The stepped care group (SC) had a significant improvement in their perceived health and a significant decrease in the amount of time spent worrying about their health. The referred care group (RC) had no change. Program assignment effects were studied in individuals aware of their hypertension and on treatment both at baseline and one year later. Both the SC and RC groups had a significant improvement in their perceptions of their health status. The SC group had a significant decrease in time spent worrying about their health, while the RC group showed no change. These reassuring results fail to support the suggestion that labeling persons as hypertensive is necessarily followed by negative psychological consequences.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
4.
5.
6.
There are at least two reasons why this Oxford handbook meritsa review in the British Journal of Anaesthesia. A proportionof readers will be involved at some time during their careerin the provision of pre-hospital care and most of us will onoccasion manage patients on their arrival in hospital followingcare for acute medical and surgical problems in the community.The Oxford series aims to act as a succinct primer in each subject,and this one succeeds. The contents page illustrates its 相似文献
7.
Evidence of sustained skeletal benefits from impact-loading exercise in young females: a 3-year longitudinal study. 总被引:4,自引:0,他引:4
Jaana A Nurmi-Lawton Adam D Baxter-Jones Robert L Mirwald Jacki A Bishop Patricia Taylor Cyrus Cooper Susan A New 《Journal of bone and mineral research》2004,19(2):314-322
The skeletal effects from intensive exercise throughout puberty are undefined. Forty-five female gymnasts and 52 controls were studied over 3 years, including a heredity aspect. The effects of size, maturity, exercise, and diet were identified using a multilevel regression model. Results demonstrated sustained skeletal benefits resulting from exercise throughout all stages of pubertal development. INTRODUCTION: Weight-bearing exercise is beneficial for peak bone mass development. However, whether skeletal benefits achieved with exercise are maintained if training remains intensive throughout the pubertal years is not entirely clear. The influence of familial resemblance for bone mass remains undefined in physically active versus inactive children. The aim of this study was to investigate the long-term influences of impact-loading exercise on bone quantity and quality in young females after controlling for growth, maturation, and hereditary factors. MATERIALS AND METHODS: At baseline, 45 gymnasts (G) and 52 normally active controls (C) 8-17 years of age were recruited. Anthropometry, diet, physical activity, and quantitative ultrasound (QUS) were measured annually for 3 consecutive years. DXA scans of total body (TB) and lumbar spine (LS) bone mineral content (BMC) and density (BMD) were taken three times at 1-year intervals. A multilevel regression model was fitted, and the independent effects of body size, maturity, physical activity, and diet were identified over time. To assess heredity influences, 27 G mothers and 26 C mothers volunteered for cross-sectional measurements of anthropometry, QUS, and BMC/BMD. RESULTS AND CONCLUSIONS: Gymnasts were smaller and lighter (as were their mothers) than controls, but they had significantly higher QUS and axial and appendicular BMC and BMD, with > 170 g more bone mineral in TB across puberty (after adjustment for maturity [years from peak height velocity], height, weight, energy, and protein intake). Gymnasts had up to 24-51% higher BMC and 13-28% higher BMD, depending on skeletal site. These results provide evidence of sustained skeletal benefits from impact-loading exercise, which are unlikely to result entirely from heredity, throughout pubertal years. 相似文献
8.
Early pharmacokinetics and clinical effects of oral D-amphetamine in normal subjects 总被引:2,自引:0,他引:2
Seven normal subjects received 0.25 mg/kg D-amphetamine orally, both after an overnight fast and again after a standard breakfast. Plasma levels, subjective and cardiovascular effects, and observer-rated activation were assessed hourly for 5 hr. Food did not affect amphetamine levels. Plasma levels peaked at 2-3 hr. Maximum cardiovascular effects generally occurred at 1 hr, whereas maximum behavioral and subjective effects occurred at 2 hr. Subjective and behavioral effects declined thereafter, in spite of substantial amphetamine levels. A separate group of 8 subjects received 0.5 mg/kg D-amphetamine orally. Plasma levels, subjective and cardiovascular effects, and activation ratings were assessed hourly for 4 hr. Maximum plasma levels were approximately twice those seen in the first group. In this case, plasma levels peaked at 3-4 hr; blood pressure and subjective and behavioral effects were all maximal at 2-3 hr and were declining by 4 hr, in spite of stable or rising plasma levels. 相似文献
9.
10.
Both cyproterone acetate (CPA) and the gonadotrophin-releasing hormone
agonist (GnRHa) have been shown to be effective for the treatment of
hirsutism. We wished to compare the effectiveness of CPA in two standard
doses with GnRHa and add-back therapy and to compare the length of
remission after these treatments. A total of 60 hirsute hyperandrogenic
women was assigned to the following treatment groups: CPA 2 mg with 35
microg of ethinylestradiol for 21 days each month (Diane group), CPA 50 mg,
days 5-15, and ethinylestradiol 50 microg, days 5-25, each month (CPA
group) or Decapeptyl 3.75 mg i.m. every 28 days with the addition of
conjugated oestrogen 0.625 mg, days 1-21, and medroxyprogesterone acetate
10 mg, days 12-21 (GnRHa group). Hirsutism was graded by the
Ferriman-Gallwey-Lorenzo (FGL) index and anagen hair shaft diameters and
serum luteinizing hormone (LH) and testosterone were assessed before and
every 3 months during and after treatment. All women were treated for 1
year with 1 year follow-up. At baseline hirsutism and endocrine patterns
were similar in all groups. After one year of treatment, hirsutism
decreased in all groups but the changes were greater (P <0.05) in the
CPA and GnRHa groups than in the Diane group. Serum LH and testosterone
were lowest in the GnRHa group. After withdrawal, hirsutism increased
rapidly in the Diane and CPA groups and after 6 months, FGL scores and hair
shaft diameters were similar to pretreatment values. In the GnRHa group,
hirsutism increased more gradually and after 1 year of withdrawal, FGL
scores and hair diameters were significantly (P <0.05) less than
pretreatment values. Serum LH and testosterone increased rapidly in all
three groups reaching pretreatment values by 6 months. These data suggest
equal efficacy of the GnRHa and the high dose CPA regimen for the treatment
of hirsutism in hyperandrogenic women. GnRHa with add-back treatment
appears to result in a longer remission of hirsutism in comparison with
CPA.
相似文献