全文获取类型
收费全文 | 12987篇 |
免费 | 520篇 |
国内免费 | 142篇 |
专业分类
耳鼻咽喉 | 31篇 |
儿科学 | 479篇 |
妇产科学 | 724篇 |
基础医学 | 1940篇 |
口腔科学 | 133篇 |
临床医学 | 674篇 |
内科学 | 1636篇 |
皮肤病学 | 112篇 |
神经病学 | 660篇 |
特种医学 | 153篇 |
外科学 | 249篇 |
综合类 | 894篇 |
现状与发展 | 1篇 |
预防医学 | 4140篇 |
眼科学 | 72篇 |
药学 | 1459篇 |
1篇 | |
中国医学 | 111篇 |
肿瘤学 | 180篇 |
出版年
2023年 | 221篇 |
2022年 | 440篇 |
2021年 | 594篇 |
2020年 | 536篇 |
2019年 | 472篇 |
2018年 | 497篇 |
2017年 | 354篇 |
2016年 | 423篇 |
2015年 | 435篇 |
2014年 | 774篇 |
2013年 | 852篇 |
2012年 | 631篇 |
2011年 | 987篇 |
2010年 | 617篇 |
2009年 | 564篇 |
2008年 | 706篇 |
2007年 | 613篇 |
2006年 | 482篇 |
2005年 | 439篇 |
2004年 | 320篇 |
2003年 | 238篇 |
2002年 | 197篇 |
2001年 | 135篇 |
2000年 | 149篇 |
1999年 | 120篇 |
1998年 | 108篇 |
1997年 | 103篇 |
1996年 | 85篇 |
1995年 | 95篇 |
1994年 | 82篇 |
1993年 | 77篇 |
1992年 | 90篇 |
1991年 | 83篇 |
1990年 | 57篇 |
1989年 | 47篇 |
1988年 | 59篇 |
1987年 | 35篇 |
1986年 | 33篇 |
1985年 | 129篇 |
1984年 | 107篇 |
1983年 | 85篇 |
1982年 | 82篇 |
1981年 | 62篇 |
1980年 | 83篇 |
1979年 | 76篇 |
1978年 | 55篇 |
1977年 | 40篇 |
1976年 | 45篇 |
1975年 | 29篇 |
1974年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
湖南省乙肝病毒基因型分布及临床意义 总被引:1,自引:0,他引:1
目的 :研究湖南省乙肝病毒 (HBV)基因型分布及临床意义。方法 :选择湖南省HBVDNA阳性慢性乙肝病人共 185例 ,其中病毒携带者 (ASC) 4 2例 ,慢性轻、中度肝炎 (CH) 38例 ,重型肝炎 (FHF) 80例 (伴有肝硬化者 4 9例 ) ,肝细胞癌 (HCC) 2 5例 ,采用聚合酶链反应 限制性片段长度多态性 (PCR RFLP)方法检测HBV基因型。结果 :基因型B136例 (73.5 % ) ,基因型C 4 9例 (2 6 .5 % )。基因型B在FHF中占绝对优势 (83.7% ) ,其次为HCC(76 % ) ,与ASC(5 7.1% )比较 ,差异有显著性 (P <0 .0 1)。与基因型B相比 ,基因型C在垂直传播感染者中多见 (38.8%与 13.2 % ,P <0 .0 0 1) ;HBeAg阳性率明显增高 (5 7.1%与 30 .9% ,P <0 .0 0 1) ;抗HBe阳性率明显下降 (36 .9%与 6 6 .2 % ,P <0 .0 0 1)。与基因型C相比 ,基因型B感染者ALT水平明显增高 (2 6 4 .5± 2 5 6 .5与 10 0± 12 0 .6 ,P <0 .0 0 1)。结论 :湖南省存在乙肝病毒基因型B和基因型C ;基因型B为优势基因型并与肝脏疾病活动性相关 ,基因型C与母婴垂直传播感染有关 相似文献
32.
M. Sivak 《Obesity reviews》2006,7(3):295-296
Caloric consumption in a society with readily available food is likely to be approximately proportional to the number of hours of being awake. Thus, replacing 1 h of inactive wakefulness (e.g. watching TV), with sleeping is likely to result in a substantial reduction in caloric intake. Calculations are presented to illustrate the possible benefits of such a switch on weight reduction. 相似文献
33.
Zhong Q. Wang Audrey D. Bell-Farrow William Sonntag William T. Cefalu 《Experimental gerontology》1997,32(6):E966-684
We report on the effect of age and chronic caloric restriction (CR) on insulin binding and glucose transporter content in both diaphragm and heart muscle membrane of young (11 months), mid-age (17 months), and old (29 month) ad libitum fed and CR Brown-Norway rats. The control animals received rat chow ad lib and CR animals were allowed 60% of ad libitum food. The CR regimen was initiated at four months of age and the animals were maintained on their respective diets until necropsy. There was no effect of age on insulin binding for either ad libitum or CR animals at each age evaluated. Caloric restriction significantly lowered insulin levels at each age studied when compared to the ad libitum-fed rats. However, CR animals were noted to have increased insulin binding (p < 0.001) compared to ad libitum-fed animals at each age for diaphragm muscle. For the heart, there appeared to be a decreased binding, particularly at higher insulin concentrations, in CR-fed animals. There was no net change in Glut-1 or Glut-4 levels for heart muscle membrane, or Glut-4 levels for diaphragm muscle membrane between ad libitum or CR animals. This data indicates that caloric restriction may have tissue-specific effects for insulin receptor binding, and that the improved insulin sensitivity in CR states is not a result of altered glucose transporter protein content. 相似文献
34.
在贵州省安顺市1985年水型伤寒爆发流行后,为调查该市环境中沙门氏菌污染情况,我站于1986~1988年对市区所属医院和贯城河污水及部分食物的沙门氏菌进行了监测,共采集污水及食品619份,沙门氏菌阳性率为41.84%,分属A、B、C、D、E1五个群12个血清型,伤寒沙门氏菌经Vi噬菌体分型为M1型。纸片药敏试验为多重性耐药菌株。阐明了沙门氏菌流行的部分传播媒介途径。 相似文献
35.
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
36.
对山东省荣成市石岛镇大渔岛村91户398名散居渔民膳食结构及营养状况调查的结果表明:①蛋白质和热能人均摄入量占平均供给量的115.4%和112.2%,其它营养素除维生素B2占83.3%以外均摄入较充足。蛋白质、脂肪、碳水化合物的热量构成比分别为11.3%、27.6%、61.1%。②查体中未发现严重的营养缺乏症。③体重指数超过正常者占13.2%。④体重指数与收缩压、舒张压经相关回归分析,呈显著相关。⑤大渔岛居民头发锌含量高于泰安农民,铜、铁含量低于泰安农民。 相似文献
37.
正常人及胃癌患者胃蛋白酶原C基因多态性研究 总被引:2,自引:0,他引:2
以PGC301为探讨,对10例胃癌组织及11例正常人体组织基因组DNA中胃蛋白酶原C基因的EcoR I限制性片段长度多态性作了观察分析。发现在正常人体有三种常见等位片段,分别为20kb、5.7kb及3.6kb;一种稀有片段,3.5kb。在胃癌患者,未发现与正常人体不同的等位片段。但是,稀有片段及稀有杂交带型的出现频率高于正常组。这一结果对深入探讨胃蛋白酶原C基因稀有片段及稀有杂交带型对胃癌的诊断价 相似文献
38.
Studies have shown that both food deprivation and response cost have important influences on the magnitude of self-administration of a wide variety of psychoactive drugs. In an attempt to extend these findings to the smoked route of drug self-administration, the effects of food allotment and fixed-ratio (FR) value were evaluated in four male rhesus monkeys trained to smoke cocaine base. In the first phase of the experiment, monkeys were trained to self-administer smoked cocaine base under a chained progressive-ratio (PR), fixed-ratio (FR) schedule during daily experimental sessions. Monkeys were required to make 20 lever-press responses and then five inhalations on a smoking spout to obtain the first smoke delivery. The lever ratio then increased to 60, 140, 300, 620, 1260, 2540, and 4940 for each successive smoke delivery. The initial lever ratio value was reset to 20 at the beginning of each daily session. The body weights of three monkeys were determined under free-feeding conditions. Monkeys were then restricted to 100 g food and, when body weights had stabilized, the daily food allotment was increased to 150 g, approximately 210 g, or greater than 400 g (satiation). As the daily food allotment and body weight increased, the mean number of smoke deliveries decreased in two of three monkeys. In the second phase of the experiment, three monkeys were maintained under either food-satiated or food-restricted conditions. Body weights were maintained at approximately 90% of their free-feeding weights under food-restricted conditions. The cost of the drug (lever FR value) was constant within each experimental session, but was increased after 3 consecutive days of stable responding. Fixed-ratio values were increased from 128 to 256, 512, 1024, and 2048. Monkeys were required to complete the lever FR value and then to make five inhalations on the smoking spout to gain access to 1.0 mg/kg per delivery cocaine base. The mean number of smoke deliveries increased at FR 256, 512, and 1024 when monkeys were food-restricted as opposed to food-satiated. Correspondingly, the mean number of responses increased under food-restricted conditions. Responding continued to increase over a wider range of FR values, and the peak number of responses was higher under food-restricted, as opposed to food-satiated conditions. These results, using the smoking route of administration, are consistent with the hypothesis that food deprivation increases the self-administration of reinforcing drugs. 相似文献
39.
Intakes and major dietary sources of cholesterol and phytosterols in the British diet 总被引:2,自引:0,他引:2
Gillian M. Morton Susan M. Lee David H. Buss Paul Lawrance 《Journal of human nutrition and dietetics》1995,8(6):429-440
Cholesterol intakes in Britain have been re-estimated by analysing Total Diet samples taken in 1991 and from 1993 National Food Survey records. The Total Diet samples contained only 284 mg/day compared with 319 mg/day in 1987 and 337 mg/day in 1981, while the National Food Survey showed intakes had fallen to 238 mg/day from 259 mg/day in 1990 and 405 mg/day in 1970-75. More details of the intakes by adults in 1986/87 are given, and compared with the results from the other methods. Daily intakes of eight phytosterols were also estimated, the main ones being β-sitosterol, campesterol, stigmasterol and 57-stigmastenol whose intakes were 104, 49, 10 and 4 mg/day, respectively, in 1991. These intakes had increased since 1981, reflecting the rising consumption of vegetable oils. 相似文献
40.
Chronic food restriction has been shown to enhance glucose metabolism in adipocytes from lean Zucker rats at 10, 26, and 52 weeks of age compared to ad libitum-fed lean rats. Only adipocytes from food restricted 10-week-old obese rats demonstrated this response. In this study, lean and obese rats were food restricted from 5 until 14 weeks of age to determine the age at which adipocytes from obese rats were no longer affected by this intervention. Effects of 1 week of refeeding were also determined. When the rats were killed, body weights were highest in control rats followed by restricted/refed and then restricted rats within each genotype. Epididymal pad weights of lean rats were resistant to dietary intervention, while those of obese-restricted and obese-restricted/refed rats weighed less than pads of obese-control rats. Retroperitoneal pad weight was lowered by food restriction in both genotypes; but only that of lean-restricted/refed rats totally recovered with refeeding. Adipocytes of lean-restricted rats had the highest conversion of glucose to CO2. Glyceride-glycerol production was higher in obese compared to lean rats, but restricted rats had elevated conversion of glucose to fatty acids. In general, these results indicate that by 14 weeks of age obese Zucker rats no longer respond to food restriction with an elevated rate of glucose metabolism in adipocytes. 相似文献