全文获取类型
收费全文 | 3299篇 |
免费 | 199篇 |
国内免费 | 77篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 85篇 |
妇产科学 | 31篇 |
基础医学 | 267篇 |
口腔科学 | 29篇 |
临床医学 | 175篇 |
内科学 | 579篇 |
皮肤病学 | 12篇 |
神经病学 | 67篇 |
特种医学 | 35篇 |
外科学 | 162篇 |
综合类 | 231篇 |
预防医学 | 1498篇 |
眼科学 | 3篇 |
药学 | 269篇 |
2篇 | |
中国医学 | 35篇 |
肿瘤学 | 93篇 |
出版年
2024年 | 4篇 |
2023年 | 81篇 |
2022年 | 174篇 |
2021年 | 191篇 |
2020年 | 182篇 |
2019年 | 155篇 |
2018年 | 152篇 |
2017年 | 97篇 |
2016年 | 126篇 |
2015年 | 88篇 |
2014年 | 236篇 |
2013年 | 269篇 |
2012年 | 171篇 |
2011年 | 197篇 |
2010年 | 142篇 |
2009年 | 150篇 |
2008年 | 194篇 |
2007年 | 119篇 |
2006年 | 110篇 |
2005年 | 82篇 |
2004年 | 69篇 |
2003年 | 53篇 |
2002年 | 49篇 |
2001年 | 46篇 |
2000年 | 33篇 |
1999年 | 37篇 |
1998年 | 28篇 |
1997年 | 18篇 |
1996年 | 14篇 |
1995年 | 23篇 |
1994年 | 22篇 |
1993年 | 17篇 |
1992年 | 18篇 |
1991年 | 21篇 |
1990年 | 21篇 |
1989年 | 14篇 |
1988年 | 12篇 |
1987年 | 15篇 |
1986年 | 11篇 |
1985年 | 24篇 |
1984年 | 14篇 |
1983年 | 22篇 |
1982年 | 19篇 |
1981年 | 14篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1975年 | 4篇 |
1972年 | 5篇 |
排序方式: 共有3575条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
ObjectivesTo assess consumption of dietary and herbal supplements (DHS) among patients in internal medicine departments and determine whether such use is documented in their medical files.Methods267 patients from three internal medicine departments of an academic medical center in Haifa, Israel were assessed prospectively with questionnaires about their DHS use in the month preceding hospitalization. DHS were categorized into vitamins & minerals, herbal supplements and others. Further data was then collected from patients' medical records on socio-demographic and medical characteristics, as well as documentation of DHS use.Results123 patients (50.6 %) used DHS on a daily basis. Most of them (53.7 %) were using more than one DHS. DHS use was more prevalent in older (OR = 1.02 [1.001–1.036], p = 0.034) and educated (OR = 0.482 [0.252-0.923], p = 0.028) patients. Vitamins & minerals were used mainly to enhance vitality and address laboratory abnormalities, whereas herbal supplements were used mainly for gastrointestinal problems (p < 0.001). DHS use was reported to the physicians by 42 % of the patients, mostly at the patients’ initiative [92 (82.1 %), p < 0.001)]. Vitamins and minerals were the most reported category of DHS (94 (57.3 %), p < 0.001). The use of DHS was reported to physicians for 112 DHS (41.8 %) but only 32 DHS (11.9 %) were documented in their medical files. The documentation of vitamins and minerals was significantly higher compared to herbal supplements documentation (29 (17.7 %) & 3 (2.9 %) respectively, P < 0.001).ConclusionsDHS are commonly used by patients hospitalized in the internal medicine departments. Many patients do not report such use to the physicians, and more strikingly, physicians do not document DHS use in patient medical files. This communication gap may have serious medico-legal ramifications due to DHS side effects and DHS interactions with other DHS and with conventional drugs. 相似文献
5.
The presence of pesticides in the Israeli food supply is well documented but little is known about the risks posed by children's diets for potential exposures. We investigated potential exposures to food-borne pesticides in a sample of 301 urban Israeli children (2008–10). Data from a food frequency questionnaire, 24 hour food recall, and Israel's national pesticide monitoring program were used to estimate uptake factors for 26 compounds in 27 fruits and vegetables. A pilot risk assessment was performed and the findings were compared with the Israel Ministry of Health's 2012 pesticide risk assessment for the general population. The surveyed children had higher potential exposures than the general population for over one third of the compounds, and uptake factors exceeded the Acceptable Daily Intake in ten compounds. Methamidophos, exceeded the ADI at the 25th percentile and fenamiphos, iprodione, and oxydemethon methyl, exceeded the ADI at the 50 percentile. ADIs for several compounds were exceeded even though the residues detected were below the statutory limit. Improved monitoring, enforcement, and revision of the Maximum Residue Limit for certain food/pesticide pairs are indicated as is the need to incorporate data on children's actual food consumption in national risk assessments. 相似文献
6.
Activity of glutathione S-transferase (GST) in midgut of gypsy moth caterpillars exposed to 10 and 30 μg Cd/g dry food was examined. Based on the enzyme reaction through conjugation with glutathione, overall activity remained unaltered after acute and chronic treatment. No-observed-effect-concentration (10 μg Cd/g dry food) significantly increased activity only after 3-day recovery following cadmium administration. Almost all comparisons of the indices of phenotypic plasticity revealed statistically significant differences. Despite the facts that GST has important role in xenobiotic biotransformation, our results indicate that this enzyme in insect midgut does not represent the key factor in cadmium detoxification. 相似文献
7.
8.
M N Martinez F R Pelsor V P Shah J P Skelly I L Honigberg S M Hemingway J M Gallo J A Kotzan R Zaman W J Brown 《Biopharmaceutics & drug disposition》1990,11(1):17-29
Quinidine gluconate 324 mg sustained release tablets (Quinaglute) was administered as a single dose to 15 healthy male subjects following an overnight fast, immediately following a high fat (HF) breakfast or immediately following a low fat (LF) breakfast. Serum samples were obtained over a 48 h period and analyzed for quinidine content using a high performance liquid chromatographic assay. Under the conditions of the study, both the rate and extent of quinidine bioavailability was significantly affected by food. The extent of bioavailability was statistically significantly greater (p less than 0.05) following both the HF and LF meals as compared to that in the fasted state. Rate of bioavailability was significantly enhanced following the LF meal as compared to that of the other two treatment groups. Although peak concentrations were greater and time to peak concentrations somewhat later following the HF meal versus those under fasting conditions, these differences were not statistically significant. In addition, the characteristics of the serum concentration-time profile (as defined by the number, magnitude, and time of occurrence of the multiple absorption maxima) was unique for each of the three treatment groups. Possible mechanisms underlying these results are explored. 相似文献
9.
The effects of 10% dietary xylitol supplementation in ovariectomized rats were studied on the degradation of bone organic
and inorganic structures. The osseal concentrations of hydroxyproline, pyridinoline, and deoxypyridinoline were analyzed by
high-performance liquid chromatography. Bone resorption was measured in [3H]tetracycline-prelabeled rats by urinary excretion of 3H, and by the amount of 3H preserved in bone. Bone trabeculation was measured by a computer image analyzer from sections stained by the method of von
Kossa. The amount of collagen in bone organic fraction was lower in ovariectomized rats as compared with the sham-operated
controls. This most likely is partly a consequence of an increased resorption, and partly a consequence of a higher proportion
of immature periosteal bone in the ovariectomized animals, leading to a higher ratio of noncollagenous protein to collagen.
The number of pyridinium crosslinks was lower in proportion, indicating no selective changes in the structure of collagen.
Dietary xylitol significantly retarded the ovariectomy-associated decrease in the relative amount of collagen and the number
of its mature crosslinks. Ovariectomy doubled the excretion of 3H and caused a significant decrease in the amount of 3H preserved in bone; both these changes were significantly retarded by the 10% dietary xylitol supplementation. Ovariectomy
significantly decreased the volume of bone trabeculae, but this effect was also significantly inhibited by the xylitol supplementation
in the diet. In conclusion, these findings suggest a dietary xylitol-induced normalizing effect on the rate of bone turnover
in ovariectomized rats.
Received: 12 February 1996 / Accepted: 20 August 1996 相似文献
10.
Because of concern about psoralen-induced phototoxicity and photocarcinogenesis, we investigated the effects of dietary lipids in a mouse model in which 8-methoxypsoralen (8-MOP) and UVA (PUVA) therapy has been shown to be carcinogenic. SKH-Hr-1 hairless albino mice were fed diets containing either omega-3 or omega-6 fatty-acid sources (menhaden oil and corn oil, respectively). After 2 weeks on the diets, the mice were treated topically with 8-MOP and then exposed to UVA (5 J/cm2). Mice receiving the omega-3 fatty-acid source exhibited a marked decrease in inflammatory response and a more rapid repair, as expressed both grossly and microscopically. In support of the latter response, i.e. repair, ornithine decarboxylase activity was about 20% greater in animals receiving the omega-3 fatty-acid source. The effects of the dietary fatty acid sources on PUVA tumorigenesis were examined in long-term studies in which animals were treated topically with 0.01% 8-MOP thrice weekly after which they were exposed to UVA (1 J/cm2). These studies indicated that a dietary lipid rich in omega-3 fatty acid and known to exhibit anti-inflammatory properties can markedly ameliorate the course of PUVA toxicity but does not impede the course of PUVA tumorigenesis 相似文献