全文获取类型
收费全文 | 315168篇 |
免费 | 12298篇 |
国内免费 | 880篇 |
专业分类
耳鼻咽喉 | 4361篇 |
儿科学 | 10643篇 |
妇产科学 | 7892篇 |
基础医学 | 40627篇 |
口腔科学 | 8080篇 |
临床医学 | 27364篇 |
内科学 | 60480篇 |
皮肤病学 | 6379篇 |
神经病学 | 23275篇 |
特种医学 | 14771篇 |
外国民族医学 | 101篇 |
外科学 | 46661篇 |
综合类 | 2951篇 |
现状与发展 | 1篇 |
一般理论 | 168篇 |
预防医学 | 27107篇 |
眼科学 | 7155篇 |
药学 | 21966篇 |
4篇 | |
中国医学 | 311篇 |
肿瘤学 | 18049篇 |
出版年
2021年 | 2137篇 |
2019年 | 2062篇 |
2018年 | 5727篇 |
2017年 | 5567篇 |
2016年 | 5024篇 |
2015年 | 7121篇 |
2014年 | 7551篇 |
2013年 | 8536篇 |
2012年 | 17273篇 |
2011年 | 12736篇 |
2010年 | 6720篇 |
2009年 | 8210篇 |
2008年 | 9828篇 |
2007年 | 11085篇 |
2006年 | 11192篇 |
2005年 | 19412篇 |
2004年 | 20493篇 |
2003年 | 15948篇 |
2002年 | 10853篇 |
2001年 | 5485篇 |
2000年 | 2595篇 |
1999年 | 7046篇 |
1998年 | 2199篇 |
1992年 | 7608篇 |
1991年 | 7795篇 |
1990年 | 8004篇 |
1989年 | 7562篇 |
1988年 | 7037篇 |
1987年 | 6770篇 |
1986年 | 6491篇 |
1985年 | 5903篇 |
1984年 | 4417篇 |
1983年 | 3738篇 |
1982年 | 2161篇 |
1981年 | 1817篇 |
1980年 | 1785篇 |
1979年 | 4290篇 |
1978年 | 2936篇 |
1977年 | 2328篇 |
1976年 | 2009篇 |
1975年 | 2881篇 |
1974年 | 3471篇 |
1973年 | 3039篇 |
1972年 | 2974篇 |
1971年 | 2874篇 |
1970年 | 2696篇 |
1969年 | 2583篇 |
1968年 | 2322篇 |
1967年 | 2251篇 |
1966年 | 1982篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
E J García Fernández R Mara?ón C Maroto E Maroto C Seri?á J L Delcán 《Revista espa?ola de cardiología》1991,44(2):115-118
We present 5 patients with cyanotic congenital heart disease in whom a pulmonary valvuloplasty was performed as palliative therapy. The patients symptoms were hypoxemic spells, very low oxygen saturation and no weight gain. The oxygenation improved and symptoms disappeared. We believe that in properly selected patients this technique represents a good therapeutic modality. 相似文献
992.
T K?hler M W Verstegen R Mosenthin T Wensing L A den Bartog J Huisman 《The British journal of nutrition》1992,68(1):305-315
In a long-term study nine ileo-rectally anastomosed (IRA) and seven post-valve T-caecum (PVTC)-cannulated pigs were compared with six intact pigs with regard to different blood variables, sodium and potassium retention and weights of selected organs. After surgery, apart from urea and K measured 13 weeks post-surgery, there were no differences in the blood variables between the PVTC-pigs and intact pigs. In IRA-pigs concentrations of creatinine (P < 0.01), Na (P < 0.001), base excess (P < 0.001), pH (P < 0.01) and bicarbonate (P < 0.001) in blood were lower than those in intact pigs. At 13 weeks after surgery the blood K concentration in IRA-pigs was higher (P < 0.001) than that in PVTC-pigs or intact pigs. At 6 weeks after surgery the blood urea concentration in IRA-pigs was higher (P < 0.001) than that in intact and PVTC-pigs. At 13 weeks after surgery the urea concentration in PVTC-pigs was higher (P < 0.001) than those in IRA-pigs or intact pigs. The Na (P < 0.01 11 weeks after surgery) and (P < 0.05 and P < 0.01 5 and 11 weeks after surgery respectively) balances in IRA-pigs were lower than those in intact animals. Na retention was negative for IRA-animals 11 weeks after surgery. Na and K retentions were similar in PVTC-pigs and in intact pigs. The urinary: faecal excretion of Na differed slightly between PVTC-animals and intact animals. At 13 weeks after surgery there were no differences in organ weights between the PVTC-pigs and intact animals. In the IRA-pigs the weights of the liver (P > 0.05), the kidneys (P > 0.05) and the adrenal glands were higher (P < 0.001) than those in the intact animals. 相似文献
993.
994.
M S Kristensen N M Wernberg E Anker-M?ller 《Infection control and hospital epidemiology》1992,13(12):719-724
OBJECTIVE: To test whether healthcare workers' knowledge of and compliance with the basic principle of the Universal Precautions policy (i.e., that all patients should be treated equally regarding contact with body fluids) influenced the rate of contact with patient blood. DESIGN: Survey based on anonymous questionnaires. SETTING: A 380-bed secondary and tertiary care hospital receiving emergency and elective patients. PARTICIPANTS: All employees having any contact with patients. Nine hundred one of 1,308 (69%) of the questionnaires were returned. RESULTS: Twelve percent of the respondents (95% confidence interval [CI95] = 10.0%-14.4%) had experienced any contact with patient blood in the week preceding their answer. Physicians had the highest rate of contact with blood followed by nurses. In the five groups--physicians, nurses, laboratory technicians and phlebotomists, nursing aides, and student nurses--contact with blood was less frequent in the subgroup that did know and comply with the basic principle of the Universal Precautions policy, compared with the subgroup that did not. When adding the results for the 5 groups, contact with blood was experienced by 91 of 571 (15.9%, CI95 = 13%-19%) of the personnel who did not know and comply with Universal Precautions. The personnel who did know and comply with Universal Precautions had a significantly lower (9 of 111 [8.1%], p < .05, CI95 = 3.8%-15%) rate of contact with blood. CONCLUSIONS: The healthcare workers who knew and complied with Universal Precautions had a significant lower rate of contact with patient blood than those who did not. 相似文献
995.
996.
M Krasnowska J Ma?olepszy E Liebhart A D Inglot 《Archivum immunologiae et therapiae experimentalis》1992,40(1):75-78
There is a relationship between viral infection and aggravation of bronchial asthma symptoms. Viruses belong to the strongest and fast acting inducers of interferon (IFN), which, in turn, may enhance histamine release from effector cells. We have administered IFN intrabronchially to 49 patients suffering from bronchial asthma. The impairment of lung ventilation with significant decrease of forced expiratory volume in one second (FEV1) have been observed in majority of the patients who inhaled crude or purified IFN preparations. 相似文献
997.
998.
Sensitivity of laser-evoked potentials versus somatosensory evoked potentials in patients with multiple sclerosis. 总被引:11,自引:0,他引:11
J?rg Spiegel Christiane Hansen Ulf Baumg?rtner Hanns Christian Hopf Rolf Detlef Treede 《Clinical neurophysiology》2003,114(6):992-1002
OBJECTIVE: Somatosensory evoked potentials (SEPs) play a less important role in the diagnosis of multiple sclerosis (MS) than visually evoked potentials. Since standard SEPs only reflect the dorsal column function, we now investigated spinothalamic tract function in patients with MS using laser-evoked potentials (LEPs). METHODS: LEPs to thulium laser stimuli (3ms, 540 mJ, 5mm diameter) were recorded from 3 midline positions (Fz, Cz, Pz) in 20 patients with MS, and 6 patients with possible but unconfirmed MS. Peak latencies and peak-to-peak amplitude of the vertex potential negativity (N2) and positivity (P2) were evaluated and compared with normative values from 22 healthy control subjects. Median and tibial nerve SEPs were recorded with standard methods. Depending on the results of sensory testing, two skin areas (both hands, both feet, or one hand and foot of the same body side) were assessed in each patient. RESULTS: In group comparisons, LEPs in patients with MS were significantly delayed and reduced in amplitude compared with healthy subjects (P<0.001) or patients with suspected but unconfirmed MS (P<0.05). In intraindividual comparisons within the patients with MS, LEP amplitude was significantly lower (P<0.01) and latencies were significantly longer (N2: P<0.01; P2: P<0.05) for a clinically hypoalgesic skin area than an unaffected control area. On a single case basis, LEPs were abnormal in 12 (60%) and SEPs in 8 (40%) of the patients with MS; combined analysis of LEPs and SEPs raised sensitivity to 75% (15 patients). LEPs were also abnormal for 7 skin areas with clinically normal nociception and thermal sensitivity, indicating subclinical lesions. Standard SEPs detected subclinical lesions in 5 areas with normal tactile sensitivity. CONCLUSIONS: In patients with multiple sclerosis, spinothalamic tract function and LEPs were impaired more often than dorsal column function and SEPs. LEPs also detected subclinical lesions. Combined assessment of LEPs and SEPs can help to document dissemination of demyelinating CNS lesions and thus contribute to the diagnosis of multiple sclerosis. 相似文献
999.
T F Schwarz A Nerlich B Hottentr?ger G J?ger I Wiest S Kantimm H Roggendorf M Schultz K P Gloning T Schramm 《American journal of clinical pathology》1991,96(1):121-126
Fetal tissues from 16 spontaneous abortions, two terminations, and one perinatal death, 18 of which were associated with maternal human parvovirus B19 infection, were examined for B19 infection by histology and in situ hybridization using a digoxigenin-labeled B19-DNA probe. In 15 spontaneous abortions and one termination, erythroblasts with intranuclear inclusions (lantern cells) reacted with B19-DNA by in situ hybridization. No internal or external fetal malformations were observed. Because 13 (86.7%) spontaneous abortions with lantern cells occurred between the 20th and 28th weeks of gestation, it is postulated that B19 infection may be a particular threat to the fetus during this stage of gestation. 相似文献
1000.
CT and MR imaging findings in adults with cerebellar medulloblastoma: comparison with findings in children. 总被引:4,自引:0,他引:4
P M Bourgouin D Tampieri S Z Grahovac C Léger R Del Carpio D Melan?on 《AJR. American journal of roentgenology》1992,159(3):609-612
The goal of this study was to determine if certain imaging features suggest the diagnosis of cerebellar medulloblastoma in adults and to determine how often the classic CT appearance seen in children is present in adults. The study included 28 adult patients with proved cerebellar medulloblastoma. The tumor was located in the cerebellar vermis in 14 patients and in a cerebellar hemisphere in 14 patients. Thirteen patients had unenhanced CT of the brain, all patients had contrast-enhanced CT, and eight patients had unenhanced MR imaging. The imaging features in adults were compared with those in children, as described in the literature. In our adult patients, all tumors were hyperdense compared with gray matter on unenhanced CT and showed a slight to moderate increase in density after injection of contrast medium. Thirteen lesions had well-defined margins, and 15 had poorly defined margins. Low-density areas consistent with cystic and necrotic degeneration were detected in 23 (82%) of the 28 tumors. By comparison, in children, medulloblastoma usually originates in the vermis. As in adults, the mass is hyperdense on unenhanced CT, but enhances markedly and homogeneously after injection of contrast medium. Usually no evidence of cyst formation or necrosis is seen, and the tumor margins are well defined. This classic CT appearance of medulloblastoma in children was identified in only three (11%) of the 28 adult patients. Medulloblastoma has a variable MR appearance in both children and adults. On T2-weighted images, lesions are hypo-, iso-, or hyperintense compared with normal gray matter. The CT findings of medulloblastoma in adults usually differ from those of medulloblastoma in children. The tumor has a variable and nonspecific appearance in adults and should always be considered in the differential diagnosis of a mass in the posterior fossa. 相似文献