全文获取类型
收费全文 | 37164篇 |
免费 | 2137篇 |
国内免费 | 201篇 |
专业分类
耳鼻咽喉 | 425篇 |
儿科学 | 1156篇 |
妇产科学 | 997篇 |
基础医学 | 3700篇 |
口腔科学 | 1212篇 |
临床医学 | 3257篇 |
内科学 | 8020篇 |
皮肤病学 | 671篇 |
神经病学 | 2211篇 |
特种医学 | 1318篇 |
外国民族医学 | 4篇 |
外科学 | 6778篇 |
综合类 | 869篇 |
现状与发展 | 3篇 |
一般理论 | 27篇 |
预防医学 | 2500篇 |
眼科学 | 1355篇 |
药学 | 2859篇 |
1篇 | |
中国医学 | 266篇 |
肿瘤学 | 1873篇 |
出版年
2024年 | 39篇 |
2023年 | 413篇 |
2022年 | 1051篇 |
2021年 | 1648篇 |
2020年 | 985篇 |
2019年 | 1255篇 |
2018年 | 1566篇 |
2017年 | 1137篇 |
2016年 | 1232篇 |
2015年 | 1332篇 |
2014年 | 1681篇 |
2013年 | 2051篇 |
2012年 | 3095篇 |
2011年 | 2993篇 |
2010年 | 1692篇 |
2009年 | 1462篇 |
2008年 | 2225篇 |
2007年 | 2294篇 |
2006年 | 2024篇 |
2005年 | 1790篇 |
2004年 | 1624篇 |
2003年 | 1351篇 |
2002年 | 1177篇 |
2001年 | 367篇 |
2000年 | 306篇 |
1999年 | 282篇 |
1998年 | 205篇 |
1997年 | 139篇 |
1996年 | 149篇 |
1995年 | 109篇 |
1994年 | 102篇 |
1993年 | 80篇 |
1992年 | 148篇 |
1991年 | 161篇 |
1990年 | 128篇 |
1989年 | 125篇 |
1988年 | 106篇 |
1987年 | 97篇 |
1986年 | 88篇 |
1985年 | 118篇 |
1984年 | 77篇 |
1983年 | 52篇 |
1982年 | 53篇 |
1981年 | 55篇 |
1980年 | 41篇 |
1979年 | 50篇 |
1978年 | 40篇 |
1975年 | 36篇 |
1974年 | 36篇 |
1973年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Melita Kosanovic Mohammad Yousif Hasan Dhanasekhar Subramanian Abdulla Ali Falah Al Ahbabi Omar Ali Awn Al Kathiri Essa Mohammed Ali Abdulla Aleassa Abdu Adem 《Food and chemical toxicology》2007,45(11):2261-2266
We hypothesized that increased ambient concentrations of metals, as a consequence of escalating urbanization and industrialization of the Gulf region will respond in increased contamination of edible fish species. In this study, we report concentrations of chromium, manganese, cobalt, copper, zinc, arsenic, cadmium, mercury and lead in meat and liver of wild Red-spot emperor (Lethrinus lentjan) from three sampling points at the UAE coast. Analysis was performed by the ICP-MS/microwave digestion. Our study has shown that meat and liver metal content was significantly higher in areas with higher industrial activity, although metal values did not exceed permitted levels of fish for human consumption. 相似文献
12.
Adult male Fisher 344 rats (8-10 wk old) were dosed ip with 1.75 mg/kg body weight of triethyllead chloride (TEL) for 5 consecutive days. Rats were sacrificed 1, 7, or 21 d after the last injection. The rate of lipid peroxidation was significantly elevated in frontal cortex at all three time points assayed (1, 7, or 21 d). However, hippocampal and cerebellar membranes showed no changes in peroxidative capacity at these time points. In order to determine whether cortical membrane damage was reflected in alteration of a restricted protein population, a series of high-affinity receptor binding sites was determined in cortical membranes derived from treated rats 7 d after the last injection of triethyllead. The rate of lipid peroxidation was significantly increased in the frontal cortex of triethyllead treated rats; however, no changes in the binding of [3H]spiroperidol, [3H]quinuclidinyl benzilate, and [3H]benzodiazepine were seen in animals exposed to triethyllead. The cortical wet weight, protein content, and cell number were also unchanged by TEL treatment, reflecting an absence of gross damage. 相似文献
13.
François Béïque Mohamed Ali Scott MacKenzie Mark Hynes 《Journal canadien d'anesthésie》2007,54(2):158-159
14.
Hasan Yüksel Ali Riza Odaba?i Selda Demircan Aslihan Karul Leyla Didem Kozaci Kutsi K?seo?lu Kadir Kizilkaya Okay Ba?ak 《Gynecological endocrinology》2006,22(7):381-387
AIM: To evaluate the effects of oral continuous 17beta-estradiol plus norethisterone acetate (E2/NETA) replacement therapy on abdominal subcutaneous fat, serum leptin level (SLL) and body composition in postmenopausal women. MATERIALS AND METHODS: A 6-month, prospective, randomized, double-blind and placebo-controlled study was conducted. Forty-three healthy naturally postmenopausal women aged 43-65 years were randomly assigned to receive E2/NETA (2 mg E2 plus 1 mg NETA, n = 22) or placebo (n = 21). Fasting SLL by enzyme-linked immunosorbent assay, subcutaneous abdominal fat thickness (STh) by ultrasound and the anthropometric indices of body weight (BW), body mass index (BMI), waist and hip circumference (WC, HC) and waist-to-hip ratio (WHR) were recorded at the beginning and the end of the study. RESULTS: After 6 months of therapy, BW and SLL increased in the placebo group (p = 0.043 and 0.033, respectively). WC, HC and STh decreased significantly in the E2/NETA group (p = 0.002, 0.006 and 0.000, respectively) and they were also significantly lower in women receiving E2/NETA than in women taking placebo (p = 0.000, 0.034 and 0.000, respectively). At baseline, SLL and STh were positively correlated with all anthropometric indices except WHR. CONCLUSION: Oral continuous combined regimen of E2/NETA significantly reduced central fat accumulation as assessed by WC and STh, and attenuated the increase in SLL. The observed changes in SLL were highly and positively related to changes in STh. The oral continuous combined E2/NETA regimen appears to have protective effects on cardiovascular function and probably on metabolic diseases by its slimming effect upon WC in postmenopausal women. 相似文献
15.
1. The effects of graded doses of the α2-adrenoceptor agonists clonidine, tizanidine and BHT-920, and the α2-adrenoceptor antagonists yohimbine and idazoxan, on gastrointestinal transit were investigated in mice using the charcoal meal test. 2. The agonists produced significant and dose-dependent decreases in gastrointestinal transit, and the antagonists produced the opposite effect. In affecting the gastrointestinal transit, clonidine (1 mg/kg) was as effective as tizanidine (12 mg/kg) and BHT-920 (40 mg/kg), while yohimbine (2 mg/kg) was as effective as idazoxan (1 mg/kg). 3. Morphine (2, 4 and 8 mg/kg) significantly inhibited gastrointestinal transit. This effect was significantly reversed by the co-administration of yohimbine (2 mg/kg) and idazoxan (1 mg/kg). 4. The acute administration of glucose (5.04 g/kg, i.p.) potentiated the inhibition of gastrointestinal transit produced by clonidine (1 mg/kg) and BHT-920 (40 mg/kg). Glucose treatment, however, had no significant effect on the increase in gastrointestinal transit induced by yohimbine (2 mg/kg) or idazoxan (1 mg/kg). 5. Castor oil (0.25 mL/mouse, orally) induced diarrhoea in saline-treated animals within about 45 min. Clonidine (1 mg/kg), tizanidine (12 mg/kg) and BHT-920 (40 mg/kg) delayed the occurrence of diarrhoea to 2.1, 1.2 and 1.4 h, respectively. 相似文献
16.
J Alió M Lude?a A Millan V Caballero V Guinaldo 《Ophthalmologica. Journal international d'ophtalmologie. International journal of ophthalmology. Zeitschrift für Augenheilkunde》1988,196(4):192-199
The authors present the results of a transmission electron-microscopic study performed on a tissue sample obtained by an intraocular fine-needle aspiration biopsy in a case of retinoma. The ultrastructural study showed that the tumor was composed mainly of granular osmiophilic material which contained some tumor cells. These cells showed peculiar ultrastructural characteristics, which demonstrated their neural character, and appeared in different degenerative stages. Apparently, this is the first case in whom ultrastructural technique have been applied to study an intraocular tumor sample obtained by intraocular fine-needle aspiration biopsy, and the first case of retinoma studied by such a diagnostic approach. 相似文献
17.
18.
M. M. Ali S. Jayabalan M. Machnicki G. S. Sohal 《International journal of developmental neuroscience》2003,21(4):199-208
Virtually all cell types in the inner ear develop from the cells of the otic vesicle. The otic vesicle is formed by the invagination of non-neural ectodermal cells known as the otic placode. We investigated whether a recently described cell population, originating from the ventral part of the hindbrain neural tube known as the ventrally emigrating neural tube (VENT) cells, also contributes cells to the otic vesicle. The ventral hindbrain neural tube cells were labeled with the fluorescent vital dye DiI or replication-deficient retroviruses containing the LacZ gene in chick embryos on embryonic day 2, after the emigration of neural crest from this region. One day later, the labeled cells were detected only in the hindbrain neural tube. Shortly thereafter, the labeled cells began to appear in the eighth (vestibulocochlear) cranial nerve and otic vesicle. From embryonic day 3.5-5, the labeled cells were detected in the major derivatives of the otic vesicle, i.e. the endolymphatic duct, semicircular canals, utricle, saccule, cochlea, and vestibulocochlear ganglion. That the emigrated cells originated from the ventral part of the hindbrain neural tube was confirmed by focal application of DiI impregnated filter paper and with quail chimeras. It is concluded that, in addition to the otic placode cells, the otic vesicle also contains the ventrally emigrating neural tube cells, and that both cell populations contribute to the structures and cell types in the inner ear. It is well known that inductive signals from the hindbrain are required for the morphogenesis of the inner ear. The migration of the hindbrain neural tube cells into the otic vesicle raises the possibility that the inductive effect of the hindbrain might be mediated, at least in part, by the ventrally emigrating neural tube cells and that, therefore, a mechanism exists that involves cells rather than diffusible molecules only. 相似文献
19.
20.
Neonatal septicaemia (NNS) is a major cause of neonatal morbidity and mortality. Neonatal septicaemia was studied to determine the incidence, common bacterial aetiology and antibiotic susceptibility in Qatif Central Hospital, Saudi Arabia. Of 1,797 babies admitted into the unit over a 3 year period, 144 (8.0%) had documented neonatal septicaemia consisting of 94 (65%) late onset and 50 (35%) early onset septicaemia. The incidence was 8.2/1000 of the total live births in the hospital.
Gram negative bacteria were encountered in 66.2%, gram positive bacteria in 29.2% and Candida albicans in 4.4% of the case. Klebsiella spp., E. coli, and Pseudomonas accounted for 81.8 % of the gram negative while Staphylococcus epidermidis, Staphylococcus aureus and group B Beta haemolytic Streptococcus accounted for 73.9% of the gram positive bacteria.
Most of Gram negative bacteria had a high sensitivity to Aminoglycosides and third generation Cephalosporins. Coagulase negative staphylococci were frequently resistant to most antibiotics but always sensitive to Vancomycin. The overall mortality rate was 18.7%. 相似文献
Gram negative bacteria were encountered in 66.2%, gram positive bacteria in 29.2% and Candida albicans in 4.4% of the case. Klebsiella spp., E. coli, and Pseudomonas accounted for 81.8 % of the gram negative while Staphylococcus epidermidis, Staphylococcus aureus and group B Beta haemolytic Streptococcus accounted for 73.9% of the gram positive bacteria.
Most of Gram negative bacteria had a high sensitivity to Aminoglycosides and third generation Cephalosporins. Coagulase negative staphylococci were frequently resistant to most antibiotics but always sensitive to Vancomycin. The overall mortality rate was 18.7%. 相似文献