全文获取类型
收费全文 | 37738篇 |
免费 | 2136篇 |
国内免费 | 109篇 |
专业分类
耳鼻咽喉 | 459篇 |
儿科学 | 2229篇 |
妇产科学 | 730篇 |
基础医学 | 4842篇 |
口腔科学 | 849篇 |
临床医学 | 2678篇 |
内科学 | 7697篇 |
皮肤病学 | 881篇 |
神经病学 | 2045篇 |
特种医学 | 862篇 |
外科学 | 5303篇 |
综合类 | 1367篇 |
一般理论 | 19篇 |
预防医学 | 2238篇 |
眼科学 | 1488篇 |
药学 | 3607篇 |
中国医学 | 288篇 |
肿瘤学 | 2401篇 |
出版年
2023年 | 222篇 |
2022年 | 342篇 |
2021年 | 1217篇 |
2020年 | 670篇 |
2019年 | 925篇 |
2018年 | 1121篇 |
2017年 | 764篇 |
2016年 | 1007篇 |
2015年 | 1044篇 |
2014年 | 1441篇 |
2013年 | 1848篇 |
2012年 | 2569篇 |
2011年 | 2594篇 |
2010年 | 1468篇 |
2009年 | 1305篇 |
2008年 | 1896篇 |
2007年 | 1858篇 |
2006年 | 1882篇 |
2005年 | 1496篇 |
2004年 | 1497篇 |
2003年 | 1276篇 |
2002年 | 1088篇 |
2001年 | 892篇 |
2000年 | 910篇 |
1999年 | 793篇 |
1998年 | 328篇 |
1997年 | 237篇 |
1996年 | 237篇 |
1995年 | 229篇 |
1994年 | 196篇 |
1993年 | 165篇 |
1992年 | 529篇 |
1991年 | 421篇 |
1990年 | 446篇 |
1989年 | 410篇 |
1988年 | 371篇 |
1987年 | 370篇 |
1986年 | 370篇 |
1985年 | 349篇 |
1984年 | 272篇 |
1983年 | 229篇 |
1982年 | 146篇 |
1979年 | 237篇 |
1978年 | 153篇 |
1977年 | 183篇 |
1975年 | 177篇 |
1974年 | 187篇 |
1973年 | 190篇 |
1972年 | 180篇 |
1971年 | 166篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
101.
Cerebral blood flow, arteriovenous oxygen difference, and outcome in head injured patients. 总被引:2,自引:0,他引:2 下载免费PDF全文
C S Robertson C F Contant Z L Gokaslan R K Narayan R G Grossman 《Journal of neurology, neurosurgery, and psychiatry》1992,55(7):594-603
Cerebral blood flow (CBF) and other physiological variables were measured repeatedly for up to 10 days after severe head injury in 102 patients, and CBF levels were related to outcome. Twenty five of the patients had a reduced CBF [mean (SD) 0.29 (0.05) ml/g/min]; 47 had a normal CBF, (0.41 (0.10) ml/g/min); and 30 had a raised CBF (0.62 (0.14) ml/g/min). Cerebral arteriovenous oxygen differences were inversely related to CBF and averaged 2.1 (0.7) mumol/ml in the group with reduced CBF, 1.9 (0.5) mumol/ml in the group with normal CBF, and 1.6 (0.4) mumol/ml in the group with raised CBF. Patients with a reduced CBF had a poorer outcome than patients with a normal or raised CBF. Mortality was highest in patients with a reduced CBF, and was 32% at three months after injury, whereas only 21% of the patients with a normal CBF and 20% of the patients with a raised CBF died. There were no differences in the type of injury, initial score on the Glasgow Coma Scale, mean intracranial pressure (ICP), highest ICP, or the amount of medical treatment required to keep the ICP less than 20 mm Hg in each group. Systemic factors did not significantly contribute to the differences in CBF among the three groups. A logistic regression model of the effect of CBF on neurological outcome was developed. When adjusted for variables which were found to be significant confounders, including age, initial Glasgow Coma Score, haemoglobin concentration, cerebral perfusion pressure and cerebral metabolic rate of oxygen, a reduced CBF remained significantly associated with an unfavourable neurological outcome. 相似文献
102.
T K Singh 《Acta cardiologica》1992,47(4):321-329
Serum ceruloplasmin levels were estimated in 81 patients within one week after an attack of acute myocardial infarction. A total of 126 healthy subjects were taken as controls and investigated for this copper containing protein. Results showed that there is an elevation in the levels of serum ceruloplasmin in patients as compared to the controls. Ceruloplasmin levels showed a return to almost normal values in 54 follow-up cases of acute myocardial infarction during the fourth week after infarction. 相似文献
103.
104.
105.
D. K. Bhargava M.D. Ph.D. B. Singh D.M. R. Dogra D.M. S. Dasarathy D.M. M. P. Sharma D.M. 《The American journal of gastroenterology》1992,87(2):182-186
A prospective randomized controlled study was designed to evaluate differences in efficacy and complication rate between the two most commonly used sclerosing agents, sodium tetradecyl sulfate (STD) and polidocanol. Of 52 patients with esophageal variceal bleeding, 26 were randomized to receive sclerotherapy with 1.5% STD and 26 to receive 1% polidocanol at weekly intervals. Eradication of varices was achieved in 88% patients each of the STD and polidocanol group. There was no significant difference between patients injected with STD and polidocanol with regard to re-bleeding (27% vs. 15%) and mortality (11.5% in both). The use of STD, in contrast to polidocanol, was associated with a higher incidence of complications in terms of severe retrosternal pain (27% vs. 4%), deep ulceration (53% vs. 23%), dysphagia (88% vs. 46%), and stricture formation (27% vs. 8%). It was concluded that these two agents were similar in efficacy. However, polidocanol was superior due to a lower incidence of complications. 相似文献
106.
A B Singh P Malik D Parkash C K Gupta 《Asian Pacific journal of allergy and immunology / launched by the Allergy and Immunology Society of Thailand》1992,10(2):103-109
Standardization of allergens are achieved by in vitro and in vivo methods. Some of the allergens from Western countries are standardized using biological potency of the extracts but no attempt has been made till now to standardize any of the pollen extracts from India based on biological units. Therefore, we have attempted to standardize two important pollen allergens Ricinus communis and Holoptelea integrifolia by biological methods. Broadly the methods adopted by Dreborg and Grimmer (1983) was followed. Skin prick tests were carried out with the extracts of R. communis and H. integrifolia on 15 allergic patients in five three fold log dilutions starting with 1:10, in 50% glycerinated buffer. Glycerinated buffer (50%) and histamine dihydrochloride (1 mg/ml) were used as negative and positive controls, respectively. The mean wheal diameter obtained with different concentrations showed a gradual systematic fall with increase in dilution. The mean relative diameter (% of histamine reaction) varied from 124.1 +/- 8.9 to 33.7 +/- 6.1 and 78.9 +/- 5.5 to 21.4 +/- 3.8 with the highest and lowest concentrations of R. communis and H. integrifolia pollen antigens, respectively. The histamine equivalent concentration of antigen 1,000 Biological Units (BU) obtained for crude pollen extracts of R. communis and H. integrifolia was 1:17 and 1:22 respectively. 相似文献
107.
A mother affected with Apert's syndrome was diagnosed by ultrasound scan at 16-17 weeks to have a fetus similarly affected. The typical features of acrocephaly and symmetrical syndactyly were seen. This is probably the first time that this condition has been diagnosed at such a gestation by ultrasound scan. The patient decided to continue the pregnancy, and intrauterine death occurred at 34 weeks. The diagnosis was confirmed by pathological examination. 相似文献
108.
We documented the presence of lymphocytic prostatitis in all prostate specimens received over a 4-month period. Lymphocytic prostatitis was present in 44% of biopsy specimens (n = 77), 95% of transurethral prostatic resection specimens (n = 20), and 100% of total prostatectomy specimens (n = 9). The patchiness of the prostatitis within the prostate in part explains the lower prevalence in the biopsy specimens, which sample a much smaller portion of the gland compared with the other procedures. Lymphocytic prostatitis was seen in prostates both with and without adenocarcinoma. However, in specimens containing carcinoma, the lymphocytic aggregates rarely involved malignant glands. Instead, the aggregates were either stromal or involved nonmalignant glands either adjacent to or away from the tumor, including glands with hyperplasia, atrophy, and prostatic intraepithelial neoplasia. Even when malignant and nonmalignant glands were in close proximity, there was a sharp demarcation with respect to lymphocytic inflammation. Immunohistochemical staining with B-cell and T-cell markers disclosed that the vast majority are T lymphocytes. The localization of lymphoid aggregates to nonmalignant (including prostatic intraepithelial neoplasia) glands but not frankly neoplastic glands, suggests a selective escape of immune detection by neoplastic glands. 相似文献
109.
Five new N alpha-(5,8-dideazapteroyl)-L-ornithines have been prepared using multistep synthetic sequences. These include N alpha-[5-(trifluoromethyl)-5,8-dideazapteroyl]-L-ornithine, 3, as well as N alpha-[5-(trifluoromethyl)-5,8-dideazaisopteroyl]-L-ornithine, 4, and its 5-fluoro and 5-chloro analogues. Both of the compounds containing a 5-(trifluoromethyl) group (3 and 4) were found to be excellent inhibitors of homogeneous hog liver folylpolyglutamate synthetase, having Ki values in the same range as N alpha-(5-chloro-5,8-dideazapteroyl)-L-ornithine, 2, (approximately 10 nM). However, the bridge-reversed isomer of 2 was 60-fold less inhibitory than 2. 相似文献
110.
K. M. Bijli† B. P. Singh S. Sridhara S. N. Gaur‡ N. Arora 《Clinical and experimental allergy》2003,33(1):65-71
BACKGROUND: Allergen extracts are unstable, heat labile or susceptible to proteases. Stability of allergen extracts is important for proper diagnosis and therapy of allergic disorders. OBJECTIVE: The present study was undertaken to determine the preservation and stabilization conditions of Imperata cylindrica (Ic) grass pollen extract. METHODS: The Ic extract was kept with 0.1 mepsilon-aminocaproic acid (EACA), 0.75 m sucrose, 5% glycerol, 0.03% human serum albumin (HSA) or 0.4% phenol for different time periods. The extracts were stored for 3, 6 and 12 months each at 4 degrees C, 4 degrees C with daily exposure to room temperature (RT) for 1 h, and RT. The quality of extracts was analysed by SDS-PAGE, Western blot, ELISA, ELISA inhibition and skin test. RESULTS: Extracts kept with EACA and sucrose retained most of the protein bands followed by glycerol as determined by SDS-PAGE and Western blot during all storage periods and conditions in comparison with standard extracts. The extracts kept with HSA, phenol and without preservative (WP) showed protein degradation below 33 kDa after 3 months storage at all conditions. However, a 67-kDa allergen was stable in these extracts. EACA extract required 75 to 120 ng of protein for 50% inhibition in IgE binding under different conditions, whereas standard extract required 70 ng for the same. ELISA also demonstrated high allergenic reactivity of EACA extract. ID test on allergy patients with EACA extract demonstrated same allergenic potency as that of standard extract. CONCLUSION: EACA is the best preservative/stabilizing agent of Ic pollen extract, followed by sucrose and glycerol. Ic extract kept with phenol, HSA and without preservative showed degradation within 3 months. EACA preserved extract is equally potent as that of standard extract up to 1 year's storage. 相似文献