全文获取类型
收费全文 | 19679篇 |
免费 | 1734篇 |
国内免费 | 801篇 |
专业分类
耳鼻咽喉 | 37篇 |
儿科学 | 452篇 |
妇产科学 | 186篇 |
基础医学 | 2145篇 |
口腔科学 | 169篇 |
临床医学 | 1546篇 |
内科学 | 3362篇 |
皮肤病学 | 124篇 |
神经病学 | 1622篇 |
特种医学 | 654篇 |
外科学 | 1591篇 |
综合类 | 2370篇 |
现状与发展 | 3篇 |
预防医学 | 1463篇 |
眼科学 | 147篇 |
药学 | 4086篇 |
7篇 | |
中国医学 | 1300篇 |
肿瘤学 | 950篇 |
出版年
2024年 | 102篇 |
2023年 | 401篇 |
2022年 | 783篇 |
2021年 | 945篇 |
2020年 | 755篇 |
2019年 | 632篇 |
2018年 | 656篇 |
2017年 | 629篇 |
2016年 | 700篇 |
2015年 | 718篇 |
2014年 | 1022篇 |
2013年 | 1408篇 |
2012年 | 1028篇 |
2011年 | 908篇 |
2010年 | 781篇 |
2009年 | 724篇 |
2008年 | 767篇 |
2007年 | 730篇 |
2006年 | 658篇 |
2005年 | 599篇 |
2004年 | 506篇 |
2003年 | 471篇 |
2002年 | 432篇 |
2001年 | 436篇 |
2000年 | 363篇 |
1999年 | 305篇 |
1998年 | 283篇 |
1997年 | 323篇 |
1996年 | 281篇 |
1995年 | 253篇 |
1994年 | 255篇 |
1993年 | 232篇 |
1992年 | 251篇 |
1991年 | 228篇 |
1990年 | 214篇 |
1989年 | 194篇 |
1988年 | 194篇 |
1987年 | 193篇 |
1986年 | 160篇 |
1985年 | 204篇 |
1984年 | 240篇 |
1983年 | 129篇 |
1982年 | 163篇 |
1981年 | 140篇 |
1980年 | 133篇 |
1979年 | 123篇 |
1978年 | 109篇 |
1977年 | 98篇 |
1976年 | 92篇 |
1975年 | 74篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Emilio Bombardieri Antonia Martinetti Rosalba Miceli Luigi Mariani Maria Rita Castellani Ettore Seregni 《European journal of nuclear medicine and molecular imaging》1997,24(11):1349-1355
Bone scintigraphy plays a major role in the diagnosis of bone metastases. The clinical utility of new biochemical markers
of bone metabolism has recently been investigated in various bone diseases. This study evaluated the role of some bone metabolism
markers in comparison with bone scan in the follow-up of breast cancer patients. We studied 149 patients with breast cancer,
33 (22%) of whom had bone metastases. IRMAs were used for the evaluation of blood levels of osteocalcin, bone alkaline phosphatase
(BAP), the C-terminal propeptide of type I procollagen and the C-terminal cross-linked telopeptide of type I collagen (ICTP).
Multivariate regression analysis showed that menopausal status (P=0.007) and metastatic bone lesions (P=0.001) affected bone marker levels. When considering post-menopausal women, the only subset in which bone metabolism marker
behaviour could be reliably investigated, we found a high degree of overlap in marker distribution for scan-positive and scan-negative
patients. Discrimination between scan-negative and scan-positive patients based on the above markers, taken singly or jointly,
was assessed by means of logistic discriminant analysis. The best discrimination was achieved with BAP, closely followed by
ICTP. BAP and ICTP together gave a slight improvement over the use of the two markers separately. However, even in this case
the degree of discrimination was poor and its clinical utility was limited. In fact, to achieve a specificity of 95%, the
sensitivity of the test was about 20%; conversely, with a sensitivity of 95%, the specificity was below 10%. In conclusion,
based on our findings, we believe that blood levels of the investigated markers cannot replace bone scintigraphy in the follow-up
of breast cancer patients for the early detection of bone metastases.
Received 14 April and in revised form 5 July 1997 相似文献
32.
Seven subjects underwent a standard localized exercise of calf muscles in order to investigate whether the metabolic exercise-induced steady-state, as revealed by the evaluation of inorganic phosphate/phosphocreatine ratio, depends on the conditioning of the muscle just prior to the exercise. The experimental protocols consisted of two separate experiments using first [31P]nuclear magnetic resonance spectroscopy and second (on 3 subjects) infrared oxyphotometry to respectively follow variation of energy metabolism and tissular deoxygenation. The exercise consisted of 240 successive plantar flexions (0.5 Hz frequency) against a high load equivalent to SO% of the maximal voluntary contraction. This exercise was accomplished before cold exercise and after warm exercise, a warming-up period bringing to approximately 50% of Vo2max. The results showed that: (1) steady-state level of phosphate/phosphocreatine and intracellular acidosis was significantly lowered by warming-up; (2) cold and warm exercise steady-state of calculated adenosine diphosphate values were not significantly different; (3) cold exercise rapidly induced a high tissular deoxygenation that is not observed during warm exercise; and (4) time-constant of phosphocreatine resynthesis is lowered after warm exercise but the initial slope of time-evolution is not modified. Parallel experiments also showed that phosphate/phosphocreatine steady-state was not modified in comparison with warm exercise when the same power of exercise was reached by stepwise incrementation of the charge. From these results we postulate that a better tissue oxygenation due to a global or localized warming-up allows to reach the same mechanical performance with a lower decrease of PCr content, owing to a faster adjustment of oxidative metabolism during the transitional period. However the aerobic pathway flux during the steady-state is probably the same before and after the warming-up despite different values of phosphate/phosphocreatine. As a consequence it can be assumed that this ratio is not a good indicator of the rate of muscle oxidative metabolism during the steady-state phase of the exercise. 相似文献
33.
α<Subscript>2β</Subscript> adrenoreceptor 301–303 deletion polymorphism in polycystic ovary syndrome
Alexandros D. Saltamavros George Adonakis Sosanna Kritikou Vasiliki Koika Kleanthis Koufogiannis Kostas Spyropoulos George Kourounis Christodoulos Flordellis Venetsana Kyriazopoulou Neoklis A. Georgopoulos 《Clinical autonomic research》2007,17(2):112-114
α2β adrenoreceptor 301–303 deletion polymorphism does not influence basal metabolic rate, insulin resistance or weight gain in
Greek women with polycystic ovary syndrome. 相似文献
34.
2型糖尿病并脂肪肝与血脂紊乱的关系探讨 总被引:2,自引:0,他引:2
目的 探讨 2型糖尿病并脂肪肝患者与脂代谢紊乱之间的关系。方法 对 60例 2型糖尿病并脂肪肝和 5 2例 2型糖尿病不并有脂肪肝病例的血脂谱 ,空腹血糖 (FPG ) ,餐后 2小时血糖 ( 2hPG) ,空腹胰岛素 (FINS)进行测定 ,计算体重指数 (BMI)及胰岛素敏感指数 (ISI)。结果 2型糖尿病并脂肪肝与不并脂肪肝相比 ,甘油三脂 (TG) ,低密度脂蛋白胆固醇 (LDL -C) ,FINS均升高 (P <0 .0 5 ,P <0 .0 1) ,而ISI明显降低 (P <0 .0 1)、脂蛋白a(Lp(a)降低(P <0 .0 5 )。结论 2型糖尿病并脂肪肝比不并脂肪肝者存在明显脂代谢紊乱及胰岛素抵抗 相似文献
35.
Peter R. Martin Sondra Levin Giovanni Impeduglia Yoomi Choe John Karanian Anil B. Mukherjee 《Psychopharmacology》1989,97(2):253-256
To determine whether prenatal thiamine deficiency, a frequent concomitant of alcoholism, reduces the response to ethanol during adulthood in the rat as does ethanol exposure in utero (Abel et al. 1981), pregnant Sprague-Dawley rats received either control or thiamine deficient diets together with daily injections of the thiamine antagonist pyrithiamine. At 7 months of age, male offspring were exposed to precisely regulated ethanol vapor concentrations in an inhalation chamber for 24 h and blood ethanol concentrations (BECs) and ethanol-induced intoxication were determined. Prenatally thiamine deficient rats and controls were indistinguishable in terms of appearance, body and liver weights, and the ratios of liver to body weight and brain to liver weight. However, total body water was significantly greater, and BECs and behavioral impairment were decreased, in the experimental rats. These findings indicate that prenatal thiamine deprivation is associated with reduced pharmacologic effect of ethanol as a result of increases in its volume of distribution and rate of metabolism. 相似文献
36.
Summary We have compared the effects of two dietary regimens with different macronutrient compositions — a macrobiotic diet and a Western diet — on drug metabolism and plasma lipids in seven healthy volunteers.The macrobiotic diet, high in carbohydrate, low in protein and fat, and devoid of animal food sources, was eaten for a ten day control period, as was the Western diet, high in calories, fat, and protein, as well as animal food sources. We determined the influences of these diets on the clearance of orally administered antipyrine, oxazepam, and methadone, as well as on plasma lipids.There was a statistically significant change in antipyrine clearance as well as in plasma LDL-cholesterol and HDL-cholesterol after the dietary periods. This suggests that the influence of dietary changes may have some effect on the clearance of therapeutic drugs. However, this is not universal and is probably important when the drug is highly dependent on the mixed-function oxidase system. 相似文献
37.
38.
C.M. Reading 《Medical hypotheses》1981,7(8):1105-1108
The aetiology of Klinefelter's Syndrome is not known. The causative factor(s) must explain the hypogonadism, low androgen levels, the disordered carbohydrate metabolism and the commonly associated psychiatric conditions. A biotin deficient/dependent state can account for the above. A biotin deficient Klinefelter's Syndrome patients with the above is described. The possible role of biotin in the primary, secondary and tertiary prevention of Klinefelter's Syndrome needs further research. 相似文献
39.
目的观察肠外营养与生长激素联合应用对大手术术后患者蛋白代谢的影响。方法将拟实施外科大手术(四类以上手术)熏APACHE-Ⅱ评分>7分的患者30例,入院后随机分为3组熏A组穴n=10雪押肠外营养治疗与生长激素穴金磊赛增雪联合治疗组(PN+GH)鸦B组穴n=10雪押肠外营养治疗组(PN)鸦C组穴n=10雪押正常补液组。其中A组在术后第2天开始给予生长激素皮下肌注,连续7d。结果术后8d内,B、C组患者均处于负氮平衡状态,血清白蛋白与胰岛素样生长因子-Ⅰ(IGF-Ⅰ)维持较低水平,A组在术后5d机体开始恢复氮平衡,血清白蛋白与IGF-Ⅰ水平逐渐上升,A组与B、C组比较差异有显著性(P<0.05)。结论较大的外科手术打击后,单纯给予常规的肠外营养要素不能被机体有效的利用,GH能够提高机体对肠外营养要素的利用率,促进机体蛋白合成。 相似文献
40.
Spermidine/Spermine N-Acetyltransferase, a New Biochemical Marker for Epithelial Proliferation in Rat Bladder 总被引:4,自引:4,他引:0
Isao Matsui-Yuasa Shuzo Otani Yoshihisa Yano Nobuyasu Takada Masa-Aki Shibata Shoji Fukushima 《Cancer science》1992,83(10):1037-1040
We examined the activity of spermidine/spermine N 1 -acetyltransferase (SAT), a rate-limiting enzyme of the biodegradation of polyamines, in N -butyl- N -(4–hydroxybutyI)nitrosamine-induced transitional cell carcinoma (TCC) and melamine-induced papillomatosis of rat bladder, and compared the activity to that of ornithine decarboxylase (ODC). Both activities were higher in both lesions than in control rats. The difference between SAT and ODC activities in cancerous tissue and papillomatosis was not significant. Cells stained for proliferating cell nuclear antigen (PCNA) were abundant in papillomatosis. TCC had areas with much PCNA. The results indicated that an elevation of SAT activity occurs in both reversible and irreversible proliferation of bladder epithelium and could be important in bladder carcinogenesis. 相似文献