全文获取类型
收费全文 | 27019篇 |
免费 | 2027篇 |
国内免费 | 101篇 |
专业分类
耳鼻咽喉 | 220篇 |
儿科学 | 623篇 |
妇产科学 | 461篇 |
基础医学 | 3633篇 |
口腔科学 | 335篇 |
临床医学 | 2933篇 |
内科学 | 5977篇 |
皮肤病学 | 340篇 |
神经病学 | 2393篇 |
特种医学 | 862篇 |
外科学 | 4554篇 |
综合类 | 291篇 |
现状与发展 | 1篇 |
一般理论 | 26篇 |
预防医学 | 2099篇 |
眼科学 | 433篇 |
药学 | 1845篇 |
中国医学 | 44篇 |
肿瘤学 | 2077篇 |
出版年
2023年 | 261篇 |
2022年 | 461篇 |
2021年 | 1021篇 |
2020年 | 524篇 |
2019年 | 829篇 |
2018年 | 955篇 |
2017年 | 662篇 |
2016年 | 679篇 |
2015年 | 780篇 |
2014年 | 1068篇 |
2013年 | 1340篇 |
2012年 | 2137篇 |
2011年 | 2182篇 |
2010年 | 1149篇 |
2009年 | 1012篇 |
2008年 | 1695篇 |
2007年 | 1654篇 |
2006年 | 1526篇 |
2005年 | 1475篇 |
2004年 | 1384篇 |
2003年 | 1315篇 |
2002年 | 1285篇 |
2001年 | 239篇 |
2000年 | 203篇 |
1999年 | 263篇 |
1998年 | 259篇 |
1997年 | 218篇 |
1996年 | 169篇 |
1995年 | 172篇 |
1994年 | 169篇 |
1993年 | 134篇 |
1992年 | 150篇 |
1991年 | 106篇 |
1990年 | 114篇 |
1989年 | 91篇 |
1988年 | 89篇 |
1987年 | 119篇 |
1986年 | 96篇 |
1985年 | 73篇 |
1984年 | 104篇 |
1983年 | 89篇 |
1982年 | 96篇 |
1981年 | 85篇 |
1980年 | 87篇 |
1979年 | 54篇 |
1978年 | 65篇 |
1977年 | 49篇 |
1975年 | 40篇 |
1974年 | 41篇 |
1971年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Magnetic Resonance Enteroclysis 总被引:5,自引:0,他引:5
Nicholas C. Gourtsoyiannis Nickolas Papanikolaou 《Seminars in Ultrasound, CT and MRI》2005,26(4):237-246
MR enteroclysis (MRE) is an emerging technique for the evaluation of small intestinal diseases. Administration of an iso-osmotic water solution through a nasojejunal catheter can guarantee adequate luminal distention, and in combination with ultrafast sequences, such as single shot TSE, true FISP, HASTE and 3D FLASH, results in excellent anatomic demonstration of the small intestine. MR fluoroscopy can be performed during MRE examination to monitor the filling process and might be useful in studying low-grade stenosis or motility related disorders. MRE is a very promising technique for the detection and characterization of involved small bowel segments in patients with Crohn's disease while its diagnostic performance in disclosing lumen narrowing and extramural manifestations and complications of the disease is outstanding. Initial experience shows that MRE is very efficient in the diagnosis of small bowel tumors and can be used in the evaluation of small bowel obstruction. 相似文献
83.
OBJECTIVES: To determine analytically the amount of potassium in raw tuberous root vegetables (TRV); to estimate the amount of potassium that can be leached from raw TRV by soaking in water; and to determine whether the duration of soaking and the cooking method selected affect potassium extraction. DESIGN: Fresh TRV (ie, fresh and sweet batata, cocomalanga, dasheen, eddo, black yam, white yam, yellow yam, yampi, malanga, red yautia, white yautia, and yuca) were obtained from an ethnic market. Five experimental conditions with variations in soak time and cooking method were applied. Potassium was extracted from the ash of dried samples. The potassium content of aqueous extractions was determined through atomic absorption spectrophotometry. RESULTS: Mean potassium content was highest in raw cocomalanga and lowest in raw dasheen. All of the raw TRV, except for dasheen, had a potassium content >200 mg (5.1 mEq)/100 g sample. Soaking was not effective in the leaching of significant amounts of potassium from most TRV. The double cooking (DC) method (ie, boil, rinse, boil again) leached more potassium from most TRV than did the normal cooking (NC) method (ie, boil), except with dasheen and yellow yam. More vegetables retained a potassium content >200 mg (5.1 mEq)/100 g following NC versus DC (92% versus 54%). CONCLUSIONS: The potassium content of raw TRV varied considerably, with most tubers retaining a moderate or high potassium content following the leaching procedures. However, this study showed that DC appears to be more effective than NC for leaching potassium from TRV. 相似文献
84.
85.
Neuronal adrenergic and muscular cholinergic contractile hypersensitivity in canine jejunum after extrinsic denervation 总被引:1,自引:1,他引:0
Bruno M. Balsiger M.D. Chong-Liang He M.D. Nicholas J. Zyromski M.D. Michael G. Sarr M.D. 《Journal of gastrointestinal surgery》2003,7(4):572-582
Extrinsic denervation may be responsible for motor dysfunction after small bowel transplantation. The aim of this study was
to examine the role of extrinsic innervation of canine jejunum on contractile activity. An in vitro dose response of cholinergic
and adrenergic agonists was evaluated in canine jejunal strips of circular muscle at 0, 2, and 8 weeks in a control group
and after jejunoileal extrinsic denervation (EX DEN). Neurons in circular muscle were quantitated by means of immunohistochemical
techniques. Adrenergic and cholinergic responses did not differ at any time in the control group. However, at 2 and 8 weeks,
extrinsic denervation caused an increased sensitivity to the procontractile effects of the cholinergic agonist bethanechol
at the level of the smooth muscle cells, and increased sensitivity to the inhibitory effects of the adrenergic agent norepinephrine
mediated at the level of the enteric nervous system. Immunohistochemical analysis showed a reduction in all neurons and a
complete lack of adrenergic fibers in the EX DEN group after 2 and 8 weeks. Extrinsic denervation induces enteric neuronal
cholinergic and adrenergic smooth muscle hypersensitivity in canine jejunal circular muscle.
Presented in part at the annual meeting of the American Gastroenterological Association, Orlando, Florida, May 18, 1999 (poster
presentation), and published as an abstract in Gastroenterology 116:A1075, 1999.
Supported by United States Public Health Service grant DK39337 from the National Institutes of Health (M.G.S.); the Swiss
National Science Foundation; the Swiss Society of Gastroenterology and Hepatology; the Swiss Foundation for Medical and Biological
Science; the Novartis Foundation; Astra Zeneca Pharmaceuticals, Switzerland; and the Department of Visceral and Transplantation
Surgery, University of Bern, Switzerland. 相似文献
86.
Nicholas G. Beratis Anasiasia Varvarigou Maria Makri Apostolos G. Vagenakis 《Clinical endocrinology》1994,40(2):179-185
OBJECTIVE Since maternal smoking causes fetal circulatory abnormalities, as well as disturbances of the maternal endocrine equilibrium, we measured the PRL, hGH and insulin-like growth factor-l (IGF-I) concentrations in the cord and venous blood of neonates of smoking mothers to determine whether or not the tobacco smoke affects the endocrine status of the neonate. DESIGN The above hormones were measured in the cord blood of the newborns of both smoking and non-smoking mothers. Also, PRL and hGH were determined at 24 and 72 hours after birth in newborns of both groups. PATIENTS Fifty-three newborns of smoking and 47 newborns of non-smoking mothers were investigated. Seventeen of the newborns of the smoking and 21 of the nonsmoking mothers were preterm. The remainder were full-term. MEASUREMENTS PRL was measured with a solid-phase immunoradiometric assay, hGH with a solid-phase two-site immunoradiometric assay and IGF-I with a solid-phase radioimmunoassay after extraction with acid-etha-nol. RESULTS The median value of PRL in the 17 preterm newborns of smoking mothers was 4941 mU/l (range 1322-7230), whereas in the 21 preterm newborns of nonsmoking mothers it was 2013 mU/l (range 243-4740) (P = 0 0002). The median hGH value in the above subjects was 1020 mU/l (range 35 2-208 4) and 59 8 mU/l (range 11 6-134-2), respectively (P = 0 0039). The median IGF-I was 580 7 U/l (range 253 2-4851 1) and 530 6 U/l (range 239 6-3591 5), respectively (P = 0 429). In the 36 full-term newborns of smoking mothers the median PRL value was 5171 mU/l (range 2074-7530), whereas in the 26 full-term newborns of non-smoking mothers it was 5081 (range 244-6540) (P = 0 048). The median hGH was 69 6 mU/l (range 42 3-280 0) and 32 2 mU/l (range 6 2-200 0), respectively (P = 0 0031). Also, the median IGF-I value was 926 3 U/l (range 348 5-5344 7) and 462 1 U/l (range 250 2-1578 7), respectively (P = 00024). On the 3rd day the PRL in the preterm neonates of both smoking and non-smoking mothers showed the same 16-5% drop, and thus the difference between the groups was maintained. A similar reduction in the hormone levels was observed in the full term neonates. CONCLUSIONS The findings indicate that the maternal tobacco-smoking causes disturbances of the endocrine status of the fetus, as shown by the increased levels of PRL, hGH and IGF-I, which are more pronounced between 30 and 37 weeks of gestation than at term. 相似文献
87.
Patrick L Splinter Konstantinos N Lazaridis Paul A Dawson Nicholas F LaRusso 《World journal of gastroenterology : WJG》2006,12(42)
AIM:To determine if novel bile acid transporters may be expressed in human tissues.METHODS:SLC10A1 (NTCP) was used as a probe to search the NCBI database for homology to previously uncharacterized ESTs. The homology search identified an EST (termed SLC10A4) that shares sequence identity with SLC10A1 and SLC10A2 (ASBT). We performed Northern blot analysis and RT-PCR to determine the tissue distribution of SLC10A4. SLC10A4 was cloned in frame with an epitope tag and overexpressed in CHO cells to determine cellular localization and functional analysis of bile acid uptake.RESULTS:Northern analysis revealed that SLC 10A4 mRNA is ubiquitously expressed fn human tissues with the highest levels of mRNA expression in brain,placenta, and liver. In SLC10A4-transfected CHO cells,immunoblotting analysis and immunofluorescence staining demonstrated a 49-kDa protein that is expressed at the plasma membrane and intracellular compartments.Functional analysis of SLC10A4 showed no significant taurocholate uptake in the presence of sodium when compared to untransfected CHO cells.CONCLUSION:To date, we have shown that this protein has no capacity to transport taurocholate relative to SLC1041; however, given its ubiquitous tissue distribution, it may play a more active role in transporting other endogenous organic anions. 相似文献
88.
Susan E Coulson Roger D Adams Nicholas J O'Dwyer Glen R Croxson 《Otolaryngology--head and neck surgery》2006,134(1):48-55
OBJECTIVE: To improve smiling after long-term facial nerve palsy (FNP). Physiotherapy rehabilitation of an adapted (more symmetrical) smile was investigated in FNP subjects 1 year post-onset, using video self-modeling (video replay of only best adapted smiles) and implementation intentions (preplanning adapted smiles for specific situations). STUDY DESIGN AND SETTING: Prospective, blinded clinical trial. Facial-Nerve-Palsy Clinic. RESULTS: After video self-modeling: 1) reaction time (RT) to initiation of adapted smiles became 224 ms faster whereas RT for everyday (asymmetrical) smiles became 153 ms slower; 2) adapted smiles were completed 544 ms faster; 3) adapted smiles had higher overall quality, movement control, and symmetry ratings; and 4) Facial Disability Index scores also improved. Implementation intentions after video self-modeling ensured transfer of adapted smile to everyday situations. CONCLUSION: Following intervention the smile improved, with significant changes in availability, execution speed, and quality. SIGNIFICANCE: This study supports these rehabilitation techniques to maximize quality of smiling following FNP. EBM rating: B-2b. 相似文献
89.
Background
Job satisfaction is important for nursing home staff and nursing home management, as it is associated with absenteeism, turnover, and quality of care. However, we know little about factors associated with job satisfaction and dissatisfaction for nursing home workers. 相似文献90.