全文获取类型
收费全文 | 21891篇 |
免费 | 1634篇 |
国内免费 | 651篇 |
专业分类
耳鼻咽喉 | 110篇 |
儿科学 | 219篇 |
妇产科学 | 162篇 |
基础医学 | 3414篇 |
口腔科学 | 1740篇 |
临床医学 | 2016篇 |
内科学 | 3777篇 |
皮肤病学 | 363篇 |
神经病学 | 1027篇 |
特种医学 | 779篇 |
外科学 | 1449篇 |
综合类 | 2229篇 |
现状与发展 | 3篇 |
预防医学 | 1739篇 |
眼科学 | 1009篇 |
药学 | 2396篇 |
7篇 | |
中国医学 | 1159篇 |
肿瘤学 | 578篇 |
出版年
2024年 | 53篇 |
2023年 | 344篇 |
2022年 | 1020篇 |
2021年 | 1392篇 |
2020年 | 837篇 |
2019年 | 769篇 |
2018年 | 753篇 |
2017年 | 703篇 |
2016年 | 739篇 |
2015年 | 787篇 |
2014年 | 1268篇 |
2013年 | 1627篇 |
2012年 | 1060篇 |
2011年 | 1229篇 |
2010年 | 958篇 |
2009年 | 866篇 |
2008年 | 887篇 |
2007年 | 859篇 |
2006年 | 776篇 |
2005年 | 740篇 |
2004年 | 615篇 |
2003年 | 560篇 |
2002年 | 500篇 |
2001年 | 436篇 |
2000年 | 353篇 |
1999年 | 292篇 |
1998年 | 318篇 |
1997年 | 284篇 |
1996年 | 262篇 |
1995年 | 233篇 |
1994年 | 217篇 |
1993年 | 197篇 |
1992年 | 199篇 |
1991年 | 171篇 |
1990年 | 154篇 |
1989年 | 134篇 |
1988年 | 148篇 |
1987年 | 138篇 |
1986年 | 141篇 |
1985年 | 200篇 |
1984年 | 172篇 |
1983年 | 116篇 |
1982年 | 144篇 |
1981年 | 107篇 |
1980年 | 89篇 |
1979年 | 86篇 |
1978年 | 57篇 |
1977年 | 60篇 |
1976年 | 53篇 |
1975年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
In 50 partially edentulous patients, 133 (48 maxillary; 85 mandibular) Astra Tech dental implants of 2 different surface textures (machined; TiO‐blasted) were alternately installed, supporting 52 fixed partial dentures (FPDs). Before abutment connection 2 machined implants (1 mandibular; 1 maxillary) were found to be non-osseointegrated and were replaced. Another implant could not be restored due to a technical complication. Two FPDs were remade because of technical complications, both because of abutment fractures. Thus, after 2 years in function, the cumulative survival rates were 97.7% and 95.7% for implants and prostheses, respectively. There was no statistically significant difference in survival rate between the 2 types of implants, 100%(TiO‐blasted) vs 95.3%(machined), P =0.24. After 2 years in function, when both jaw and type of implants were combined, the mean (SD) marginal bone loss was 0.24 (0.69) mm. No statistically significant difference in bone loss was found between the 2 tvues of implant after 2 years of loading, 0.04 (0.82) mm, P >0.30. 相似文献
142.
COLLETTE BRITTON GERMINAL J. CANTO GEORGEM. URQUHART MALCOLM W. KENNEDY 《Parasite immunology》1993,15(11):625-634
Immunofluorescence on live Dictyocaulus viviparus parasites revealed a significant antibody response by vaccinated and patently infected bovine hosts to the sheath of infective larvae (L3), a structure which is generally thought to be shed from the parasite surface prior to invasion of host tissue. In contrast, surface-exposed antigens of the adult, egg and pulmonary L1 stages were recognized only by serum antibody from calves exposed to a patent lungworm infection. Radioiodination of sheathed L3 identified a restricted set of components while a more complex pattern of labelled material was observed with adult parasites. Many more components of adult worms were labelled by the Bolton-Hunter than by the lodogen reagent, probably reflecting the more penetrative labelling propensities of the former. Stage-specificity of surface-associated antigens of adult parasites was demonstrated by their immunoprecipitation by antibody from patently-infected, but not from vaccinated, calves. There was no in vitro release of the major iodinatable surface-associated antigens of adult parasites nor any binding of antibody raised against adult excretory-secretory (ES) products to the surface of living adult worms, suggesting that surface components do not contribute to adult ES products in this species. Antibody responses to the surface of adults. L1 and eggs were specific to patently-infected animals and may provide a useful indicator of exposure to patent infection. 相似文献
143.
A. D. Katsen B. Vollmar P. Mestres-Ventura M. D. Menger 《Virchows Archiv : an international journal of pathology》1998,433(1):75-83
Tumour necrosis factor (TNF)-α-induced apoptosis is associated with several nuclear and cell surface alterations, in particular
with the condensation of chromatin and the fragmentation of the cell nucleus, formation of blebs on the cell surface and breakdown
of the plasma membrane. However, there is little information about the relationship between the cell surface alterations and
the nuclear changes during apoptosis. To study this, cultured WEHI cells were exposed to TNF-α over different time periods.
The cytological changes were studied using a correlative approach, which allowed observation of the same cell consecutively
under light, scanning and transmission electron microscopy. The earliest sign of cell alteration was a reduction of the number
of microvilli after 15 min of TNF-α exposure. This reaction was reversible (reappearance of microvilli) and took place during
the first hour, in which neither nuclear alterations nor plasma membrane breakdown were observed. The changes in the nucleus
began with condensation of chromatin after approximately 1 h of TNF-α-exposure. After 4–5 h the microvilli disappeared again,
particularly in areas where the formation of blebs (blebbing) was observed. Strikingly, cell surface alterations (bleb formation)
were detected only in those cells that presented with condensed chromatin, and not in cells with a normal chromatin pattern,
proving at least a close correlation between nuclear and cell surface changes during the process of apoptosis.
Received: 7 October 1997 / Accepted: 23 March 1998 相似文献
144.
Translated fromBuylleten' Eksperimental'noi Biologii i Meditsiny, Vol. 115, No. 1, pp. 21–23, January, 1993 相似文献
145.
Surface EMG in the recording of fasciculations. 总被引:2,自引:0,他引:2
The usefulness of multichannel surface recording of fasciculations was evaluated by a retrospective study of 116 patients with various neurological disorders. Eight channels of a conventional electroencephalograph were used with plate electrode recordings from the upper arms and legs. Wide-spread fasciculations (defined as five or more of the eight muscle groups) were recorded in 48 of 54 patients with motor neuron disease, spinal muscular atrophy or postpolio syndrome, but noted on routine clinical examination at presentation in only 6. Eleven of 23 patients with peripheral neuropathy or myelopathy had fasciculations in five or more leads compared to one clinically, and 3 of 39 with other neurological diseases had fasciculations electrically but in only one were they clinically observed. The method is a noninvasive and sensitive adjunct to clinical examination for detecting fasciculations. Its diagnostic value is limited by the relatively high incidence of fasciculations in neuropathies and myelopathies. However, this study suggests that "false negatives" are rare and that the diagnosis of motor neuron disease should be reconsidered when less than five leads shows fasciculations. 相似文献
146.
目的:观测纯静脉皮瓣术后血流量和血管网面密度变化。方法:利用家兔耳背设计纯静脉皮瓣和动脉皮瓣模型①观测术后血流量;②墨汁灌注后软蜡厚蜡切片,图像分析血管网面密度。结果:①纯静脉皮瓣术后48h血流量最低,第14d恢复至术前65%。②纯静脉皮瓣术后第1~7d的血管网面密度高于动脉皮瓣(P<0.05)。结论:纯静脉皮瓣术后血流量及血管网密度变化与动脉皮瓣不同。 相似文献
147.
Inflammatory foci are rich in proteases released by neutrophils (serine proteases) and macrophages (metalloproteases). These enzymes can degrade extracellular matrix proteins and cell membrane bound proteins thus contributing to the development and progression of inflammatory reaction. In this study we have investigated the influence of collagenase (metalloprotease) and trypsin (serine protease) on murine resident and oil-induced peritoneal macrophages (Mf). Short in vitro treatment of Mf, not affecting cell viability, significantly reduced the release of reactive oxygen intermediates (ROIs) and at the same time triggered the increase of IL-6 production and to lesser extent of TNF-alpha production. Both these effects were dependent on enzyme concentration used and were particularly well pronounced in resident macrophages. In addition both enzymes cleaved a number of cell-membrane molecules, including CD23, CD14, CD95L, and Mac-3. We hypothesize that the enzymatic digestion of certain Mf surface receptor proteins in inflammatory foci may be responsible for modification of cell behaviour either by preventing the generation of specific signal or alternatively by delivering a mock substitute signal to the cell interior. In effect inhibition of ROIs production limits their destructive effects and the increase in the secretion of IL-6 stimulates the synthesis of acute phase proteins and triggers other anti-inflammatory mechanisms thus directing Mf present in inflammatory foci into regulatory pathway rather than allowing them to perform solely the effector function. 相似文献
148.
One hundred forty-nine specimens were tested in a LightCycler nested multiplex polymerase chain reaction (LCnmPCR) for Herpes simplex virus (HSV)1, HSV2, and VZV. Eighty-one were from genitourinary medicine (GUM) patients and the other 68 specimens were from other patients with skin lesions. The results were compared to a conventional multiplex nested PCR (nmPCR) using agarose gel electrophoresis. Twenty-five specimens were positive in both assays for HSV1 and 29 were positive for VZV. For HSV2 there were 27 positive in the LCnmPCR and 26 positive in the nmPCR assay. The melting temperatures (Tms) of each target were different with a mean of 84.75 degrees C for HSV1, 88.57 degrees C for HSV2, and 83.62 degrees C for VZV. The melting curves of positive specimens directly overlaid the melting curves of the positive controls in the assay. The LCnmPCR assay is a convenient alternative to conventional PCR using agarose gel electrophoresis. It improves specimen turnaround time by eliminating the need for gel electrophoresis, transillumination, and gel photography. It also shows increased sensitivity for HSV2 over our standard assay. This LCnmPCR reduces further the possibility of amplicon contamination with nested PCR protocols. 相似文献
149.
门静脉的体表定位及其临床意义 总被引:3,自引:0,他引:3
目的:为超声波检查门静脉或经皮经肝门静脉穿刺提供解剖学基础。方法:在40例成人尸体标本上观测了门静脉的行程及其分叉位置的体表投影。结果:门静脉肝外段与身体的垂线呈约40°角;门静脉分叉位置在经右半胸宽中点的垂线与右锁骨中线上肝高中点的水平线的交点附近;门静脉右支分为前、后支的位置在剑突尖平面下方约2cm,右锁骨中线上肝高的中点附近;门静脉左支分出第1外侧支的位置在剑突尖稍下方的右侧约2cm。结论:在右腋中线剑突尖平面下方约2cm经皮经肝穿刺至锁骨中线,导管即可进入门静脉右支内 相似文献
150.
Motoko Yanase Hideto Tanaka Teruo Nakayama 《European journal of applied physiology》1989,58(4):446-451
Summary In female rats, rectal temperature (T
re), tail vasomotor response, oxygen uptake
, and carbon dioxide production
were measured in proestrus and estrus stages during treadmill running at two different speeds at an ambient temperature (T
a) of 24° C. Experiments were performed at 2.00–6.00 a.m., when the difference inT
re was greatest between the two stages;T
re at rest in the estrus stage was 0.54° C higher than in the proestrus stage. In a mild warm environment, thresholdT
re for a rise in tail skin temperature (T
tail) was also higher in the estrus stage than in the proestrus stage. In contrast, no difference was seen in the thresholdT
re and steady stateT
re at the end of exercise between proestrus and estrus stages. These values were higher at the higher work intensity.
was also similar between the two stages, except in the second 5 min after the beginning of exercise, when
was greater andT
re rose more steeply in the proestrus stage. These data indicate that deep body temperature during exercise is regulated at a certain level depending on the work intensity and is not influenced by the estrus cycle.This study was supported in part by a Grant-in Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan (Grant No. 62480114) 相似文献