全文获取类型
收费全文 | 7296篇 |
免费 | 489篇 |
国内免费 | 235篇 |
专业分类
耳鼻咽喉 | 36篇 |
儿科学 | 169篇 |
妇产科学 | 91篇 |
基础医学 | 1613篇 |
口腔科学 | 211篇 |
临床医学 | 611篇 |
内科学 | 1464篇 |
皮肤病学 | 47篇 |
神经病学 | 293篇 |
特种医学 | 222篇 |
外科学 | 415篇 |
综合类 | 934篇 |
现状与发展 | 1篇 |
一般理论 | 1篇 |
预防医学 | 1027篇 |
眼科学 | 30篇 |
药学 | 433篇 |
7篇 | |
中国医学 | 208篇 |
肿瘤学 | 207篇 |
出版年
2023年 | 117篇 |
2022年 | 229篇 |
2021年 | 366篇 |
2020年 | 293篇 |
2019年 | 211篇 |
2018年 | 219篇 |
2017年 | 246篇 |
2016年 | 253篇 |
2015年 | 300篇 |
2014年 | 456篇 |
2013年 | 501篇 |
2012年 | 423篇 |
2011年 | 506篇 |
2010年 | 425篇 |
2009年 | 400篇 |
2008年 | 373篇 |
2007年 | 359篇 |
2006年 | 326篇 |
2005年 | 278篇 |
2004年 | 208篇 |
2003年 | 233篇 |
2002年 | 149篇 |
2001年 | 186篇 |
2000年 | 124篇 |
1999年 | 136篇 |
1998年 | 66篇 |
1997年 | 65篇 |
1996年 | 66篇 |
1995年 | 58篇 |
1994年 | 64篇 |
1993年 | 36篇 |
1992年 | 32篇 |
1991年 | 31篇 |
1990年 | 33篇 |
1989年 | 28篇 |
1988年 | 26篇 |
1987年 | 12篇 |
1986年 | 19篇 |
1985年 | 20篇 |
1984年 | 20篇 |
1982年 | 17篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 14篇 |
1978年 | 11篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1974年 | 7篇 |
1972年 | 6篇 |
排序方式: 共有8020条查询结果,搜索用时 109 毫秒
31.
Friedrich Manz Hermann Kalhoff Thomas Remer 《Pediatric nephrology (Berlin, Germany)》1997,11(2):231-243
In early infancy, complex disorders of acid base metabolism are more frequent than in any other age group, with a predisposition
to metabolic acidosis due to an age-related low renal capacity for acid excretion and an unphysiologically high actual renal
acid load in nutrition with common formulas. Recently in preterm and small-for-gestational-age infants, persistent maximum
renal net acid excretion (NAE) with subnormal or normal blood acid base status, impaired weight gain, and adaptive hormonal
reactions have been observed. Incipient late metabolic acidosis is one example of a mixed disorder of acid base metabolism
with maximum renal NAE in early infancy. Alkali therapy is highly effective and can be realized both on an individual basis,
using urine pH screening as a diagnostic criterium for maximum renal acid stimulation, or on a general preventive level using
modified standard formula with a reduced actual renal NAE similar to that seen on alimentation with human milk. From an integrated
point of view, the low glomerular filtration rate and renal capacity for acid excretion beyond the developmental age of more
than 44 weeks, may well be interpreted as the result of a specific adaptation to breast feeding sparing energy, and thus an
evolutionary advantage for the survival of mother and child.
Received July 10, 1996; received in revised form and accepted October 7, 1996 相似文献
32.
33.
Andor Erdelyil Teuvo Sihvonen Pertti Helin Osmo Hänninen 《International archives of occupational and environmental health》1988,60(2):119-124
Summary Keyboard work consists mostly of dynamic contractions of the small muscles of the forearms and hands. This is accompanied by continuous activity in the arm, shoulder and neck muscles keeping the head and hand in the correct position. Eliminating the weight from the arm by means of support and the position of the arms influences the electrical activity of shoulder muscles when working at a keyboard. We studied the influence of elbow angle, as well as that of different arm supports, on electrical activity of upper trapezius muscle during keyboard work in healthy workers and persons suffering from shoulder pains. The measurements were carried out in the laboratory. EMG activities, which where measured as mean square root (RMS)-values at every 100-millisecond period in trapezius muscle when working, were lower, the greater the elbow angle. Furthermore electrical activity decreased when subjects used arm supports while working. It is evident that the static load to shoulder muscles can be lowered significantly in keyboard work, when the forearms are at an angle of at least 100 degrees and by using arm supports. The most convienient and ergonomic working position can also be found individually be the method used here. 相似文献
34.
病毒性心肌炎心肌线粒体结构功能变化及大剂量维生素C干预作用 总被引:3,自引:0,他引:3
目的:探讨病毒性心肌炎(VMC)小鼠心肌线粒体结构和功能,并用大剂量维生素C进行干预。方法:雄性Balb/c小鼠随机分为柯萨奇B3病毒(CVB3)感染组(IG)、CVB3感染加大剂量维生素C治疗组(IVG)和对照组(CG)。采用电镜和形态计量学方法观察心肌线粒体形态、数量和膜磷脂定位,用酶细胞化学法分析心肌线粒体细胞色素氧化酶(CCO)和琥珀酸脱氢酶(SDH)活性。结果:IG小鼠心肌线粒体大量破坏,CCO和SDH活性降低,膜磷脂严重缺失、定位改变(P <0.05~ 0.01)。不同时相点IVG上述各项指标均较IG显著改善(P <0.05~0.01)。结论:VMC心肌线粒体结构严重破坏、功能明显下降,大剂量维生素C能有效保护心肌线粒体结构和功能。 相似文献
35.
36.
Devices that are pinned to the tibia to tension an anterior cruciate ligament (ACL) graft produce joint reaction loads that in turn can affect the maintenance of graft initial tension after tibial fixation and hence knee anterior-posterior (AP) load-displacement. However, the effect of these devices on AP load-displacement is unknown. Our objectives were to determine whether tensioning by device versus tensioning by hand causes differences in AP load-displacement and intraarticular graft tension for two commonly used tibial fixation devices: a bioresorbable interference screw and a WasherLoc. AP load-displacement and intraarticular graft tension were measured in 20 cadaveric knees using a custom arthrometer. An initial tension of 110 N was applied to a double-looped tendon graft with the knee at extension using a tensioning device pinned to the tibia and a simulated method of tensioning by hand. After inserting the tibial fixation device, the 134 N anterior limit (i.e., anterior position of the tibia with respect to the femur with a 134 N anterior force applied to the tibia) and 0 N posterior limit (i.e., AP position of the tibia relative to the femur with a 0 N force applied to the tibia) were measured with the knee in 25 degrees flexion. Intraarticular graft tension was measured at extension. These limits and intraarticular graft tension were also measured after cyclically loading the knee 300 times. Compared to a simulated method of tensioning by hand, tensioning with a device pinned to the tibia did not decrease the 134 N anterior limit and did not cause posterior tibial translation. However, intraarticular graft tension was maintained better with a tensioning device pinned to the tibia for the Washerloc, but not the interference screw. For two commonly used tibial fixation devices, a tensioning device pinned to the tibia does not improve AP load-displacement at 25 degrees flexion over tensioning by hand when the graft is tensioned at full extension, but does improve the maintenance of intraarticular graft tension for the Washerloc. 相似文献
37.
背景 已知慢性应激与抑郁发生相关,非稳态负荷(AL)作为评估机体慢性应激反应的综合生理指标可能在抑郁的发生过程中起着重要作用。目的 探讨妊娠早期女性AL水平与抑郁的关系。方法 采用便利抽样法,选取2021年11月—2022年6月于中国人民解放军联勤保障部队第901医院、六安市金安区妇幼保健院产检的630例妊娠早期女性为研究对象,根据有无抑郁分为抑郁组(n=162)和非抑郁组(n=468)。采用一般资料调查表、妊娠相关焦虑量表、爱丁堡产后抑郁量表进行问卷调查,通过体格检查和实验室检查收集AL相关数据。采用多因素Logistic回归模型分析妊娠早期女性AL与抑郁的相关性。结果 630例妊娠早期女性抑郁发生率为25.7%(162/630)。低水平AL(AL<3分)孕妇427例(67.8%),高水平AL(AL≥3分)孕妇203例(32.2%)。多因素Logistic回归分析显示,高水平AL是妊娠早期女性抑郁的危险因素[OR=1.651,95%CI(1.096,2.489),P<0.05]。结论 妊娠早期女性AL与抑郁存在正向关联,高水平AL会增加抑郁的发生风险。 相似文献
38.
Cytomegaloviruses encode homologs of cellular immune effector proteins, including chemokines (CKs) and CK receptor-like G protein-coupled receptors (GPCRs). Sequence of the guinea pig cytomegalovirus (GPCMV) genome identified an open reading frame (ORF) which predicted a 101 amino acid (aa) protein with homology to the macrophage inflammatory protein (MIP) subfamily of CC (β) CKs, designated GPCMV-MIP. To assess functionality of this CK, recombinant GPCMV-MIP was expressed in HEK293 cells and assayed for its ability to bind to and functionally interact with a variety of GPCRs. Specific signaling was observed with the hCCR1 receptor, which could be blocked with hMIP −1α in competition experiments. Migration assays revealed that GPCMV-MIP was able to induce chemotaxis in hCCR1-L1.2 cells. Antisera raised against a GST-MIP fusion protein immunoprecipitated species of ∼12 and 10 kDa from GPCMV-inoculated tissue culture lysates, and convalescent antiserum from GPCMV-infected animals was immunoreactive with GST-MIP by ELISA assay. These results represent the first substantive in vitro characterization of a functional CC CK encoded by a cytomegalovirus. 相似文献
39.
K. Nagamani Manisha Rani Vishnuvardhan Reddy Panduranga Rao Sushma Rajyalakshmi Sunitha Pakalapaty 《Indian journal of medical microbiology》2022,40(1):12-17
PurposeNoroviruses are common viral agents in acute diarrhea in all age groups worldwide. Norovirus has been classified into 10 genogroups, GI to GX with over 48 genotypes among them the GII.4 genotype has evolved over time with a clear pattern of periodic variant replacement. Immunity is strain or genotype specific with little or no protection conferred across genogroups. The present study was aimed to determine the epidemiology, prevalent genotypes of norovirus in children below five years of age in the Hyderabad region, India.MethodsThe stool samples and clinical data were collected from 458 children below 5 years of age comprising of cases with acute gastroenteritis (n ?= ?366) and a control group (n ?= ?92) admitted to the pediatric ward. All the samples were tested for Norovirus by ELISA and RT-PCR. Sequencing was done for predominant strains.Results10.3% (n ?= ?38) of cases and 3.2% (n ?= ?3) of the control group were found to be Norovirus positive. Predominant genotypes were GII-82.5% followed by GI-12.5%.ConclusionSequencing and Phylogenetic analyses of 20 GII.4 strains was done. All of the isolates are clustered away from published the GII.4 variants thus suggesting the appearance of a new variant. 相似文献
40.