全文获取类型
收费全文 | 4352篇 |
免费 | 233篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 23篇 |
儿科学 | 207篇 |
妇产科学 | 175篇 |
基础医学 | 615篇 |
口腔科学 | 45篇 |
临床医学 | 396篇 |
内科学 | 943篇 |
皮肤病学 | 94篇 |
神经病学 | 408篇 |
特种医学 | 161篇 |
外科学 | 500篇 |
综合类 | 49篇 |
一般理论 | 1篇 |
预防医学 | 375篇 |
眼科学 | 47篇 |
药学 | 264篇 |
中国医学 | 7篇 |
肿瘤学 | 276篇 |
出版年
2021年 | 57篇 |
2020年 | 31篇 |
2019年 | 57篇 |
2018年 | 82篇 |
2017年 | 38篇 |
2016年 | 46篇 |
2015年 | 54篇 |
2014年 | 78篇 |
2013年 | 127篇 |
2012年 | 172篇 |
2011年 | 213篇 |
2010年 | 103篇 |
2009年 | 112篇 |
2008年 | 162篇 |
2007年 | 182篇 |
2006年 | 141篇 |
2005年 | 164篇 |
2004年 | 156篇 |
2003年 | 124篇 |
2002年 | 143篇 |
2001年 | 151篇 |
2000年 | 153篇 |
1999年 | 136篇 |
1998年 | 64篇 |
1997年 | 34篇 |
1996年 | 42篇 |
1995年 | 28篇 |
1993年 | 38篇 |
1992年 | 101篇 |
1991年 | 121篇 |
1990年 | 134篇 |
1989年 | 98篇 |
1988年 | 90篇 |
1987年 | 74篇 |
1986年 | 84篇 |
1985年 | 80篇 |
1984年 | 64篇 |
1983年 | 38篇 |
1982年 | 43篇 |
1981年 | 38篇 |
1980年 | 34篇 |
1979年 | 62篇 |
1978年 | 46篇 |
1977年 | 57篇 |
1976年 | 40篇 |
1975年 | 35篇 |
1974年 | 35篇 |
1972年 | 42篇 |
1971年 | 38篇 |
1970年 | 35篇 |
排序方式: 共有4586条查询结果,搜索用时 0 毫秒
51.
52.
53.
D. Oberladstätter W. Voelckel C. Schlimp J. Zipperle B. Ziegler O. Grottke H. Schöchl 《Anaesthesia》2021,76(3):373-380
In urgent clinical situations, such as trauma, urgent surgery or before thrombolysis, rapid quantification of direct oral anticoagulant plasma drug levels is warranted. Using the ClotPro® analyser, we assessed two novel viscoelastic tests for detection of clinically-relevant plasma drug levels in trauma patients. The ecarin clotting time was used to assess the plasma concentration of dabigatran and Russell´s viper venom clotting time to determine the plasma concentration of direct factor Xa inhibitors. In parallel, plasma concentrations were analysed using plasma-based chromogenic assays. A total of 203 simultaneous measurements were performed. Strong to very strong linear correlations were detected between ecarin clotting time and plasma concentration of dabigatran (r = 0.9693), and between Russell´s viper venom clotting time and plasma concentrations of apixaban (r = 0.7391), edoxaban (r = 0.9251) and rivaroxaban (r = 0.8792), all p < 0.001. An ecarin clotting time ≥ 189 seconds provided 100% sensitivity and 90% specificity for detecting plasma dabigatran concentrations ≥ 50 ng.ml-1. Corresponding Russell´s viper venom clotting time cut-off values were ≥ 136 seconds for apixaban (80% sensitivity, 88% specificity), ≥ 168 seconds for edoxaban (100% sensitivity, 100% specificity) and ≥ 177 seconds for rivaroxaban (90% sensitivity, 100% specificity). Detection of drug levels ≥ 100 ng.ml-1 was also investigated: for dabigatran, an ecarin clotting time ≥ 315 seconds yielded 92% sensitivity and 100% specificity; while Russell´s viper venom clotting time cut-offs of 191, 188 and 196 seconds were calculated for apixaban (67% sensitivity, 88% specificity), edoxaban (100% sensitivity, 75% specificity) and rivaroxaban (100% sensitivity, 91% specificity), respectively. We have demonstrated strong positive correlations between plasma drug levels and clotting time values in the specific ClotPro assays. Cut-off values for detecting clinically-relevant drug levels showed high levels of sensitivity and specificity. 相似文献
54.
55.
Between January 1981 and December 1988 a total of 95 patients underwent surgery for adrenal tumors. In 24 cases (25.3%) a so-called "incidentaloma" was found. While seven of these tumors showed hormonal activity, in seventeen patients the tumor was hormonal inactive. The size of the tumors ranged between 2 and 11 cm. Histologically all tumors were found to be benign neoplasms. Because of the lack of lethality and minimal morbidity we indicate surgery on incidentaloma of the adrenal gland for the following reasons: tumors with hormone activity, tumor size larger than 3 cm, suspecting malignoma or metastasis and finally in proven enlargement of small tumors. Only in adrenal tumors smaller than 3 cm we suggest a follow-up by ultrasound or computed tomography. 相似文献
56.
Angela Unkroth Jürgen Kleinschmidt Wolfgang Ziegler Birgit Hofmann Matthias Jütte 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》1993,231(5):303-307
We describe a new multipurpose method for corneal refractive surgery by using a focused excimer laser beam, which allows the application of a small, compact low-energy excimer laser. It is possible to ablate any area desired in the cornea without masking by scanning the focused beam. The ablation depths in freshly enucleated swine eyes were measured in relation to the number of laser pulses (at fixed fluence) and the pulse fluence at wavelengths = 248 nm and =193 nm. The irradiation conditions were investigated to obtain smooth ablation of the corneal material over an area of about 1 cm2. The experiments show that smooth ablation is obtained when the ratio of the excimer laser beam spot diameter on the corneal surface and the displacement for one scanning step is given by a whole number. A simple model based on rectangular beam profiles is presented to exemplify this. 相似文献
57.
Synthesis and structure-activity relationships of new 7-[3-(fluoromethyl)piperazinyl]- and -(fluorohomopiperazinyl)quinolone antibacterials 总被引:1,自引:0,他引:1
C B Ziegler P Bitha N A Kuck T J Fenton P J Petersen Y I Lin 《Journal of medicinal chemistry》1990,33(1):142-146
Some novel 6-fluoro-7-substituted-1,4-dihydro-4-oxoquinoline-3-carboxylic acids have been prepared. At the N-1 position "standard" substitution was employed with the ethyl, cyclopropyl, and p-fluorophenyl groups being used. At C-7 the introduction of some novel piperazines was made. Most notably, 2-(fluoromethyl)piperazine (10) and hexahydro-6-fluoro-1H-1,4-diazepine (16, fluorohomopiperazine) at the quinolone C-7 position produced products with similar in vitro antibacterial activity as the ciprofloxacin reference. The in vivo efficacy of 1-cyclopropyl-6-fluoro-7-[3-(fluoromethyl)piperazinyl]-1,4-dihydro-4- oxoquinoline-3-carboxylic acid (20) was excellent with better oral absorption than ciprofloxacin (2). 相似文献
58.
The effect of indomethacin on the activity of five different flavoenzymes, three dehydrogenases and six hydrosases, was determined. Indomethacin at concentration 1.0 mM inhibited the activity, in decreasing order of sensitivity, of the following flavoenzymes: D-amino acid oxidase (pig kidney), flavin-containing monooxygenases (pig liver microsomal), cyclohexanone monooxygenase (Acinetobacter), NADPH-quinone reductase (pig liver), and glutathione reductase (yeast), but it had no effect on the activity of glucose oxidase (Aspergillus) or liver microsomal NADPH-cytochrome P-450 reductase. Indomethacin was competitive with D-alanine for the D-amino acid oxidase (Ki=30 microM) and with NADPH for all other flavoenzymes sensitive to this compound (Kis 170-500 microM). While indomethacin also inhibited two of the three NAD(P)+-dependent dehydrogenases tested, the Kis were relatively high (<1, 500 microM), and of the six different hydrolases tested only one, liver microsomal esterase, was inhibited by indomethacin (Ki=600 microM). Indomethacin also inhibited aminopyrine demethylation catalyzed by the liver microsomal P-450 monooxygenase (Ki=1,000 microM). Although the exact mechanism for the inhibition of functionally different flavoenzymes sensitive to indomethacin is not known, the inhibition is probably not due to the detergent properties of this drug. 相似文献
59.
This study assessed the nutrient intake, body composition and biochemical indices of National Figure Skating Championship competitors. Four-day diet records, fasting blood samples, and anthropometric measurements were obtained 2 months after the National Championships from 41 figure skaters 11-18 years of age. Energy, carbohydrate, fat, dietary fiber and cholesterol intake were significantly lower compared to the NHANES III averages for adolescents in the U.S. In general, the mean intakes for most vitamins except vitamin D and E were above the recommended intake. But the athletes had lower intakes of vitamin E and B12, and higher intakes of vitamin C, and thiamin (females only) compared with NHANES III. The mean intakes of magnesium, zinc, and iodine by the male skaters were below the recommended levels, as were the mean intakes of calcium, iron, phosphorus, magnesium, and zinc by the female skaters. Also, the number of servings from vegetable, fruit, dairy, and meat groups were below the recommended levels. Biochemical indices of nutritional status were within normal limits for all skaters. But plasma electrolyte concentrations were indicative of potential dehydration status. The results suggest there is a need to develop dietary intervention and educational programs targeted at promoting optimal nutrient and fluid intakes by these athletes to maintain performance and improve long-term health status. 相似文献
60.
G Ursin A H Wu R N Hoover D W West A M Nomura L N Kolonel M C Pike R G Ziegler 《American journal of epidemiology》1999,150(6):561-567
Breast cancer incidence has historically been 4-7 times higher in the United States than in Asia. A previous study by the authors in Asian-American women demonstrated a substantial increase in breast cancer risk in women who migrated from Asia to the United States, with the risk almost doubling during the first decade after migration. Increased use of oral contraceptives soon after migration to the United States could possibly explain this rapid rise in risk. In a population-based case-control study of Chinese, Filipino, and Japanese-American women, aged 20-55 years, who lived in San Francisco-Oakland, California; Los Angeles, California; and Oahu, Hawaii during 1983-1987, 597 cases (70% of those eligible) and 966 controls (75%) were interviewed. Controls were matched to cases on age, ethnicity, and area of residence. Oral contraceptive (OC) use increased with time since migration; 15.0% of Asian-born women who had been in the West <8 years, 33.4% of Asian-born women who had been in the West > or =8 years, and 49.6% of Asian women born in the West had ever used OCs. However, duration of OC use (adjusted for age, ethnicity, study area, years since migration, education, family history of breast cancer and age at first full-term birth) was not associated with increased risk of breast cancer. Moreover, neither OC use before age 25 years nor before first full-term birth was associated with increased risk. Results were unchanged when restricted to women under age 45 years or under age 40 years. After adjustment for duration of OC use, women who had been in the United States > or =8 years were still at almost twice the risk of breast cancer compared with women who had been in the United States 2-7 years. This study suggests that OC use cannot explain the elevated risk observed in Asian women who migrated to the United States > or =7 years ago. 相似文献