全文获取类型
收费全文 | 928087篇 |
免费 | 75033篇 |
国内免费 | 2016篇 |
专业分类
耳鼻咽喉 | 13296篇 |
儿科学 | 26635篇 |
妇产科学 | 26279篇 |
基础医学 | 133015篇 |
口腔科学 | 26844篇 |
临床医学 | 82442篇 |
内科学 | 178569篇 |
皮肤病学 | 17887篇 |
神经病学 | 76428篇 |
特种医学 | 37314篇 |
外国民族医学 | 172篇 |
外科学 | 145100篇 |
综合类 | 25511篇 |
现状与发展 | 2篇 |
一般理论 | 329篇 |
预防医学 | 72804篇 |
眼科学 | 22149篇 |
药学 | 69181篇 |
1篇 | |
中国医学 | 1663篇 |
肿瘤学 | 49515篇 |
出版年
2018年 | 8873篇 |
2016年 | 7797篇 |
2015年 | 9145篇 |
2014年 | 13249篇 |
2013年 | 19726篇 |
2012年 | 27443篇 |
2011年 | 28641篇 |
2010年 | 16608篇 |
2009年 | 15525篇 |
2008年 | 26936篇 |
2007年 | 29395篇 |
2006年 | 29226篇 |
2005年 | 28622篇 |
2004年 | 28022篇 |
2003年 | 26805篇 |
2002年 | 25721篇 |
2001年 | 36435篇 |
2000年 | 36931篇 |
1999年 | 31566篇 |
1998年 | 10041篇 |
1997年 | 9227篇 |
1996年 | 9057篇 |
1995年 | 8570篇 |
1994年 | 8162篇 |
1992年 | 27022篇 |
1991年 | 26416篇 |
1990年 | 25894篇 |
1989年 | 24960篇 |
1988年 | 23495篇 |
1987年 | 23100篇 |
1986年 | 21998篇 |
1985年 | 21362篇 |
1984年 | 16681篇 |
1983年 | 14308篇 |
1982年 | 9207篇 |
1981年 | 8540篇 |
1980年 | 8005篇 |
1979年 | 16947篇 |
1978年 | 12349篇 |
1977年 | 10367篇 |
1976年 | 9465篇 |
1975年 | 10254篇 |
1974年 | 12745篇 |
1973年 | 12236篇 |
1972年 | 11612篇 |
1971年 | 10756篇 |
1970年 | 10279篇 |
1969年 | 9957篇 |
1968年 | 8933篇 |
1967年 | 8252篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
141.
In order to clarify the reported discrepancies in S100 alpha protein and mRNA distribution in rat tissues, a rat S100 alpha cDNA has been isolated and this species homologous probe along with a rat S100 beta cDNA probe has been used to examine S100 mRNA expression in rat tissues. Although the rat S100 alpha cDNA was missing approximately 30 nucleotides of coding sequence, only 4 conservative changes in amino acid sequence were observed when the deduced amino acid sequence was compared to the bovine S100 alpha amino acid sequence. Thus, S100 alpha proteins, like S100 beta proteins, are highly conserved among species. All nineteen of the tissues examined (including cerebrum and cerebellum) contained S100 alpha mRNA. In addition, S100 beta mRNA was detected in thirteen of the nineteen tissues examined. These results are in agreement with previous protein distribution studies and further demonstrate that S100 proteins are not brain-specific and are expressed in a large number of tissues. Although S100 alpha and S100 beta mRNAs were detected in rat tissues which had previously been reported to contain S100 alpha and S100 beta protein, a direct correlation between the protein and mRNA levels were not observed, suggesting that different mechanisms regulate S100 expression in various tissues. S100 alpha exhibited a single similar size mRNA species (0.5 Kb) in all tissues examined, as did S100 beta (1.5 Kb), suggesting that the individual S100 proteins are expressed as single mRNA and protein products in rat tissues. 相似文献
142.
R W Deitrick 《The Journal of sports medicine and physical fitness》1991,31(3):367-375
A physiological comparison of the responses of typical weight (less than 90 kg) versus heavy weight (greater than 90 kg) male triathletes to maximal treadmill and maximal bicycle exercise was performed to better understand the effects of weight on endurance performance. The heavy triathlete group (90.9 +/- 3.2 kg, mean +/- SD) had significantly (p less than .01) greater percent body fat (11.9 +/- 3.6 vs 7.4 +/- 1.8%) while having significantly (p +/- .01) lower VO2max values expressed in ml.kg-1.min-1 on both the treadmill (55.6 +/- 4.1 vs 69.9 +/- 5.5) and bicycle ergometer (51.9 +/- 3.9 vs 60.5 +/- 6.2) than the typical triathlete group (66.6 +/- 5.9 kg). Analysis of covariance using body fat as the covariate resulted in persistent significant (p less than .02) VO2max (ml.kg-1.min-1) differences between the groups. Statistically significant (p less than .05) differences in running economy existed between the groups (33.7 +/- 2.7 vs 37.1 +/- 1.5 ml.kg-1.min-1; typical vs heavy). The heavy triathletes also had a significantly (p less than .01) shorter treadmill performance time (9.6 +/- 2.3 vs 13.2 +/- 1.7 min) and significantly (p less than .01) lower power per weight ratio on the bicycle ergometer (5.37 +/- 0.48 vs 6.47 +/- 0.59 watts/kg). These findings indicate that the heavy triathlete is at a physiological disadvantage when competing in endurance events and supports the inclusion of a weight category in these events. The reported triathlon results support these physiological findings. 相似文献
143.
N M Whear J D Langdon D W Macpherson 《International journal of oral and maxillofacial surgery》1991,20(6):357-359
A new surgical technique for the treatment of recurrent temporomandibular joint subluxation or dislocation is described. Following a horizontal osteotomy and down-fracture of the articular eminence an inter-positional bovine cartilage xenograft is inserted in order to augment the vertical height of the eminence. The procedure combines simplicity with minimal post-operative morbidity. The increase in eminence height is both predictable and stable. 相似文献
144.
Cochlear ablation in deafness mutant mice: 2-deoxyglucose analysis suggests no spontaneous activity of cochlear origin 总被引:3,自引:1,他引:2
Deafness mutant mice show no stimulus-related cochlear potentials as well as abnormal electrically-evoked responses recorded from the inferior colliculus. Abnormal spontaneous activity in the auditory periphery could result in abnormal development and/or maintenance of the central auditory pathways. We therefore assessed spontaneous activity of cochlear origin in the central nuclei of the mutants by ablating one cochlea and subsequently using the 2-deoxyglucose (2DG) technique to study metabolic activity. Any asymmetries in labeling in a given nucleus should be due to spontaneous activity in the cochlear nerve on the unoperated side. In control animals (+/dn mice undergoing unilateral cochlea ablation), statistically significant decreased 2DG labeling was observed in the ipsilateral PVCN and AVCN, and contralateral MNTB and IC; all receive primary excitatory input from the ablated ear. No significant differences in labeling between right and left sides were observed in any of the nuclei studied in the mutant animals. These findings suggest that there is no spontaneous activity of cochlear origin in these mutants, even though many cochlear nerve fibers and spiral ganglion cells survive. 相似文献
145.
R G Amedee W J Mann J M Gilsbach 《Archives of otolaryngology--head & neck surgery》1989,115(9):1103-1106
The anatomic principles and operative techniques currently applied to functional endoscopic endonasal surgery have allowed for significant refinements in another approach to regional pathology that uses the operating microscope, newly designed sinus instruments, and a self-retaining nasal speculum system. The main benefits of this method are the superb widefield stereoscopic vision and the distinct freedom to work bimanually. Additionally, direct bipolar cautery of bleeders is afforded while use of the observer tube or video allows for excellent teaching. The precise nature of this surgery affords less fear of serious complications in the treatment of periorbital, paranasal sinus, and parasellar diseases. We describe technical aspects of the surgery and associated complications in 219 patients treated from 1984 to 1987. 相似文献
146.
M W Dronfield 《British medical journal》1987,294(6583):1308-1309
147.
G Ciprandi A Scordamaglia S Ruffoni G Pizzorno G W Canonica 《Current medical research and opinion》1986,10(5):346-350
Fifteen patients with cutaneous signs and symptoms caused by adverse reactions to foods were treated in an open trial with ketotifen for 4 to 6 weeks. Seven subjects were allergic and 8 had food intolerance. Each patient was treated with a single dose of ketotifen daily: 2 mg half an hour before going to sleep. Clinical improvement was achieved in 6 out of 7 allergic patients and in 6 out of 8 patients with food intolerance. Since several drugs have been demonstrated to have an influence on immune response, the in vitro effects of ketotifen on some immunological parameters were also studied. Ketotifen showed a significant inhibitory effect on autologous mixed lymphocyte reaction responsiveness. 相似文献
148.
Many important pharmaceutical agents, including vancomycin, bleomycin, cyclosporin, and several antibiotics, are produced by non‐ribosomal peptide synthetase (NRPS) enzymes in microorganisms. The NRPS pathway produces an extensive library of products using multienzyme complexes acting in an assembly‐line fashion. Engineering an NRPS system to produce an even greater variety of products, some of which may also have beneficial therapeutic value, would be an enormous advantage. Several approaches have been successful in generating novel NRPS products: mutational biosynthesis during which nonnatural substrates are fed to an organism; domain and module swapping between different species to generate hybrid enzymes; and rational site‐directed mutagenesis, based either on phylogeny or computational prediction, intended to switch substrate specificity and produce altered products. This review will highlight the progress in these areas and describe research in the future that will extend the capacity for re‐engineering NRPS systems. Drug Dev. Res. 66:9–18, 2006. © 2006 Wiley‐Liss, Inc. 相似文献
149.
In 50 children, 4 months to 12 years of age, with minor head trauma non-target visual event-related potentials were performed and compared to a second registration of the potentials some months later. On following-up there was a clear tendency for a relative improvement of the latencies of the endogenous potentials. In this way non-target visual event-related potentials proved to be of value in the investigation of mental impairment in early childhood. 相似文献
150.
The neuroprotective effects of dizocilipine maleate (MK-801), a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptor/channel, were tested in the 4-vessel occlusion rat model of forebrain ischemia. Adult Wistar rats, treated intraperitoneally with MK-801 or saline using several different treatment paradigms were subjected to 5 (n = 208) or 15 (n = 62) min of severe, transient forebrain ischemia. In saline-treated animals, 15 min of ischemia (n = 13) produced extensive and consistent loss of pyramidal neurons in the CA1 zone of hippocampus. The degree and distribution of cell loss were not reduced by single dose preischemic administration of MK-801 at 1 (n = 7), 2.5 (n = 4), or 5 mg/kg (n = 8). In other animals subjected to 15 min of forebrain ischemia, multiple doses of MK-801 (5, 2.5, and 2.5 mg/kg) given immediately and at approximately 8 and 20 hr after cerebral reperfusion (n = 5) did not alter CA1 injury compared to saline-treated controls (n = 5). Five minutes of forebrain ischemia in saline-treated animals, (n = 82) resulted in significantly fewer (p less than 0.001) dead CA1 pyramidal cells and a greater variance compared to animals subjected to 15 min of ischemia. Power analysis of the preliminary saline-treated animals subjected to 5 min of ischemia (n = 22) indicated that 60 animals per group were necessary to detect a 15% difference between MK-801 and vehicle-treated groups. Multidose treatment with MK-801 (1 mg/kg) given 1 hr prior to 5 min of ischemia (n = 60) and again at approximately 8 and 16 hr after recirculation failed to attenuate hippocampal injury.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献