全文获取类型
收费全文 | 4650篇 |
免费 | 477篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 19篇 |
儿科学 | 167篇 |
妇产科学 | 104篇 |
基础医学 | 680篇 |
口腔科学 | 135篇 |
临床医学 | 550篇 |
内科学 | 986篇 |
皮肤病学 | 24篇 |
神经病学 | 364篇 |
特种医学 | 285篇 |
外科学 | 649篇 |
综合类 | 120篇 |
一般理论 | 6篇 |
预防医学 | 464篇 |
眼科学 | 62篇 |
药学 | 279篇 |
肿瘤学 | 256篇 |
出版年
2022年 | 33篇 |
2021年 | 51篇 |
2020年 | 27篇 |
2019年 | 47篇 |
2018年 | 61篇 |
2017年 | 53篇 |
2016年 | 64篇 |
2015年 | 82篇 |
2014年 | 111篇 |
2013年 | 132篇 |
2012年 | 180篇 |
2011年 | 210篇 |
2010年 | 141篇 |
2009年 | 106篇 |
2008年 | 199篇 |
2007年 | 213篇 |
2006年 | 168篇 |
2005年 | 196篇 |
2004年 | 184篇 |
2003年 | 175篇 |
2002年 | 154篇 |
2001年 | 162篇 |
2000年 | 160篇 |
1999年 | 172篇 |
1998年 | 67篇 |
1997年 | 55篇 |
1996年 | 57篇 |
1995年 | 62篇 |
1994年 | 53篇 |
1993年 | 62篇 |
1992年 | 132篇 |
1991年 | 114篇 |
1990年 | 124篇 |
1989年 | 124篇 |
1988年 | 121篇 |
1987年 | 108篇 |
1986年 | 101篇 |
1985年 | 91篇 |
1984年 | 86篇 |
1983年 | 70篇 |
1982年 | 53篇 |
1981年 | 36篇 |
1980年 | 31篇 |
1979年 | 49篇 |
1978年 | 47篇 |
1977年 | 41篇 |
1976年 | 35篇 |
1975年 | 34篇 |
1974年 | 47篇 |
1973年 | 40篇 |
排序方式: 共有5150条查询结果,搜索用时 0 毫秒
1.
2.
The aim of the study was to determine the effect of exogenous melatonin treatment on circulating prolactin levels in red deer. Melatonin was administered from 12 June 1984 (day 1) to lactating and non-lactating hinds in the feed daily at 1600 h, and to non-lactating hinds by a subcutaneous implant. Average concentrations (ng/ml) of prolactin in plasma taken serially over 15-h periods were significantly higher for untreated hinds than for melatonin-treated animals on day 15 whether lactating (66-133 v. 23-28, P less than 0.05) or non-lactating (28-174 v. 8-13, P less than 0.01), remained higher on day 36 (lactating: 41-152 v. 15-21, P less than 0.05; non-lactating: 21-50 v. 1-7, P less than 0.001) but had decreased to similar levels on day 72 (lactating: 5-24 v. 7-17; non-lactating: 2-9 v. 0-4). The advanced reduction in plasma prolactin for all melatonin-treated hinds was associated with an advanced onset of seasonal breeding activity. 相似文献
3.
Hans D de Boer Jan van Egmond Jacques J Driessen Leo HD Booij 《Neuropsychiatric Disease and Treatment》2007,3(5):539-544
Steroidal neuromuscular blocking agents (NMBAs), such as rocuronium, are widely used in clinical anesthesia and emergency medicine to facilitate endotracheal intubation and artificial ventilation and to allow surgical access to body cavities. Reversal of neuromuscular blockade is important for the acceleration of patient recovery and prevention of postoperative residual neuromuscular blockade and reduces the incidence of severe morbidity and mortality associated with anesthesia management. Sugammadex is the first selective relaxant binding agent (SRBA) and has been designed to reverse the steroidal neuromuscular blocking drug rocuronium. Encapsulation of the rocuronium molecule by sugammadex results in a rapid decrease in free rocuronium in the plasma and subsequently at the nicotinic receptor at the motor endplate. After encapsulation, rocuronium is not available to bind to the nicotinic receptor in the neuromuscular junction. This promotes the liberation of acetylcholine receptors, and muscle activity reappears. This new concept of reversal of neuromuscular block induced by rocuronium (or vecuronium) led to impressive results in animal and phase 1 and 2 studies. Sugammadex is currently in phase 3 clinical studies and may be commercially available by 2008. 相似文献
4.
The myxozoan parasite Ceratomyxa shasta is a virulent pathogen of salmonid fish in the Klamath River, Oregon/California, USA. We previously defined four principal genotypes of the parasite (O, I, II, III) based on a trinucleotide repeat (ATC)0–3 in Internal Transcribed Spacer region 1 sequences. Genotypes occur in sympatry and show marked host preference: I in Chinook salmon (Oncorhynchus tschawytscha) and II in non-native rainbow trout (O. mykiss). In the present study, we sequenced the parasite from river water samples collected in May, June and September at three localities below, above and between the Klamath's five dams. We also sampled adult and juvenile coho salmon (O. kisutch), steelhead trout (O. mykiss, anadromous form) and native redband rainbow trout (O. mykiss, freshwater form) and additional Chinook salmon and non-native rainbow trout. We found that the C. shasta population was highly structured spatially, temporally and with respect to fish host species. Genotype O was present in water throughout the basin but detected almost exclusively in steelhead and native rainbow trout. Genotype I was in water only below the dams and detected only in Chinook salmon. Genotype II was detected in coho salmon below the dams, and in non-native rainbow trout exposed both above and below the dams. The same genotypes were detected in adult and juvenile fish of the same species. These findings have major implications for the design of effective surveillance and control programs for this economically and ecologically important fish parasite. 相似文献
5.
Stephanie Atkinson 《Canadian Medical Association journal》2004,170(8):1208-1209
6.
Thomas L. Patterson Shirley J. Semple Lydia R. Temoshok J. Hampton Atkinson J. Allen McCutchan Kristy A. Straits-Trster James L. Chandler Igor Grant 《Journal of Applied Biobehavioral Research》1993,1(1):64-87
The significance of life stress, coping, and social support was examined in relation to depressive symptomatology in a sample of 160 asymptomatic and mildly symptomatic HIV-antibody-positive (HIV+) men. The participants (mean age = 32 years) were interviewed about the life stress that they had experienced in the previous 6 相似文献
7.
8.
9.
B W Brown E N Atkinson J R Thompson E D Montague 《Journal of the National Cancer Institute》1987,78(3):425-435
The degree of concordance of growth rates of primary tumors with corresponding recurrences was investigated by using data from 184 patients with breast cancer with measurable recurrences. For conduction of this examination, the detection processes of both the primary tumor and the recurrence were explored. The probability of detection of a recurrence per unit time was found to be nearly proportional to the tumor's diameter. Approximately 60,000 cells initiated the recurrence, and the distribution of doubling times of the recurrences was exponential, with a mean of 2.1 months. The probability of detection of the primary tumor per unit time was approximately proportional to its volume. The distribution of doubling times of primary tumors was nearly exponential; from other evidence, we inferred that the mean doubling time was also close to 2.1 months. Several techniques to measure growth rate agreement between the primary and recurrent tumors within individuals were developed, and all of them yielded the result that the growth rates are nearly unrelated. 相似文献
10.
Effect of blockade of TNF-alpha and interleukin-1 action on bone resorption in early postmenopausal women. 总被引:1,自引:0,他引:1
Natthinee Charatcharoenwitthaya Sundeep Khosla Elizabeth J Atkinson Louise K McCready B Lawrence Riggs 《Journal of bone and mineral research》2007,22(5):724-729
After acute estrogen withdrawal in postmenopausal women, administration of anakinra or etanercept, specific blockers of IL-1 and TNF-alpha, respectively, reduced the rise in bone resorption markers to about one half of that in controls. This is consistent with an important role for these immune cytokines in mediating the effect of estrogen deficiency on bone. INTRODUCTION: Studies in rodents have implicated increased production of interleukin (IL)-1 beta and TNF-alpha as mediators of bone loss after ovariectomy, but their roles are unclear in humans whose immune system differs markedly from that of rodents. MATERIALS AND METHODS: We administered transdermal estradiol, 0.1 mg/d, for 60 days to 42 early postmenopausal women. Estrogen treatment was discontinued, and subjects were randomly assigned to intervention groups receiving 3 wk of injections with 0.9% saline, anakinra 100 mg/d, or etanercept 25 mg/twice weekly. Bone turnover was assessed by measuring serum carboxyl-terminal telopeptide of type 1 collagen (CTX) and amino-terminal telopeptide of type 1 collagen (NTX), markers for bone resorption, and serum amino-terminal propeptide of type 1 collagen (P1NP), a marker for bone formation. Results were expressed as percent change in markers from baseline (last 2 days of estrogen treatment and days 20 and 21 of intervention). RESULTS: The percent changes from baseline during intervention for serum CTX, urine NTX, and serum PINP, respectively, were 43.3 +/- 8.0%, 12.0 +/- 7.1%, and -41.0 +/- 2.5% for the control group; 25.9 +/- 6.3%, 9.5 +/- 4.0%, and -37.8 +/- 3.0% for the anakinra group; and 21.7 +/- 5.0%, 0.32 +/- 3.82%, and -34.5 +/- 3.9% for the etanercept group. Compared with the control group, the blunting of the increase in serum CTX fell just below the level of significance (p=0.10) after anakinra treatment, whereas the blunting of the increase in serum CTX (p=0.034) and in urine NTX (p=0.048) were significant after etanercept treatment. Other changes were not significant. CONCLUSIONS: The data are consistent with a role for TNF-alpha, and possibly for IL-1 beta, in mediating increased bone resorption during estrogen deficiency in women. Although either cytokine blocker reduced serum CTX by about one half, the effect of combined blockade could not be tested because of concerns about toxicity. The data do not exclude direct or indirect contributory roles for RANKL or for other cytokines. 相似文献